Hydraulic control device for automatic transmission

The disclosure of Japanese Patent Application No. 2007-311250 filed on Nov. 30, 2007 and Japanese Patent Application No. 2008-212217 filed on Aug. 20, 2008 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

The present invention relates to a hydraulic control device for an automatic transmission.

Generally, in a multi-stage automatic transmission installed in vehicles, each shift speed is achieved by controlling the rotating state of each rotating element included in a speed change gear mechanism based on the engaged state of a plurality of friction engagement elements. The engaged state of these friction engagement elements is controlled by electrically adjusting the engaging pressure using a solenoid valve and supplying the engaging pressure to a hydraulic servo of each friction engagement element.

In the automatic transmission, when a failure occurs where no electricity is supplied to the solenoid valve, or a so-called solenoid-all-off state, electrical shift control using the solenoid valve is impossible. The solenoid-all-off state occurs, for example, when the control unit (ECU) is down, battery wiring is broken, and a short-circuit occurs.

To solve this problem, Japanese Patent Application Publication No. JP-A-2001-90829 proposes that, when such solenoid-all-off state occurs during running (in a forward range), two types of shift speeds are achieved in accordance with the shift speed before the occurrence of the solenoid-all-off state without using the electrical pressure regulation control of the solenoid valve, thus securing continuous running performance. More specifically, the device in Japanese Patent Application Publication No. JP-A-2001-90829 is structured such that, if the solenoid-all-off state occurs between a forward first speed and a forward third speed, the forward third speed is achieved, and if the solenoid-all-off state occurs between a forward fourth speed and a forward sixth speed, the forward sixth speed is achieved. Therefore, a low-speed running performance is secured if the solenoid-all-off state occurs during low-speed running, while high-speed running performance is secured if the solenoid-all-off state occurs during high-speed running. The device in Japanese Patent Application Publication No. JP-A-2001-90829 is structured such that forward third speed is achieved if the engine is restarted after the vehicle is stopped and the engine is stopped after the occurrence of the solenoid-all-off state, thereby making it possible to restart the vehicle, which is referred to as limp-home function.

The device disclosed in Japanese Patent Application Publication No. JP-A-2001-90829 is provided with three valves in total: a fail-safe shift valve (VA) to switch the shift speed to achieve two types of shift speeds (forward sixth speed, forward third speed) when the solenoid-all-off state occurs; a high shift speed storage shift valve (VB) to store the state of high speed and output hydraulic pressure to the fail-safe shift valve at a high speed; and a high shift speed cancel shift valve (VC) to cancel the storage state of the high speed in the high shift speed storage shift valve (or four valves if an abnormality detection solenoid valve (SE) to change the signal pressure between normal time and failure time is included).

The three valves and a complicated oil passage structure to achieve their functions are not required during normal running unless the solenoid-all-off state occurs. As a fail-safe device prepared in an emergency, the structure lacks compactness and the number of valves is large, making it expensive.

To address this, an object of the present invention is to provide a hydraulic control device for an automatic transmission that is capable of promoting compactness and cost reduction while achieving, when a failure resulting in non-energizing occurs, low speed or high speed in accordance with the shift speed before the occurrence of the failure. The present invention can also achieve various other advantages.

According to an exemplary aspect of the invention, a hydraulic control device for an automatic transmission includes a first solenoid valve that supplies a first operating hydraulic pressure to a hydraulic servo of a first friction engagement element; a second solenoid valve that supplies a second operating hydraulic pressure to a hydraulic servo of a second friction engagement element; a third solenoid valve that supplies a third operating hydraulic pressure to a hydraulic servo of a third friction engagement element and is a normally open solenoid valve that outputs the third operating hydraulic pressure during non-energizing; a preliminary shift speed switching valve that switches to a low speed side position in order to output a first preliminary hydraulic pressure for the hydraulic servo of the first friction engagement element and a high speed side position in order to output a second preliminary hydraulic pressure for the hydraulic servo of the second friction engagement element based on an engaged state of the second friction engagement element; and a hydraulic pressure supply switching valve that switches to a normal position that supplies the first and second operating hydraulic pressures to the hydraulic servos of the first and second friction engagement elements, respectively, and a failure position that supplies the first and second preliminary hydraulic pressures to the hydraulic servos of the first and second friction engagement elements, respectively, at a failure resulting in non-energizing. The second friction engagement element is engaged at high speed side shift speeds, a low speed that is one of low speed side shift speeds is achieved by engagement of the first friction engagement element and the third friction engagement element, and a high speed that is one of the high speed side shift speeds is achieved by engagement of the second friction engagement element and the third friction engagement element.

Various exemplary aspects of the invention will be described with reference to the drawings, wherein:

FIG. 1 is a skeleton diagram showing an automatic transmission according to the present invention;

FIG. 2 is an engagement table of the automatic transmission;

FIG. 3 is a velocity diagram of the automatic transmission;

FIG. 4 is a circuit diagram showing a hydraulic control device for an automatic transmission according to a first embodiment; and

FIG. 5 is a circuit diagram showing a hydraulic control device for an automatic transmission according to a second embodiment.

First Embodiment

The following describes a first embodiment according to the present invention with reference to FIG. 1 through FIG. 4 .

Outline Structure of Automatic Transmission

First, the outline structure of an automatic transmission 3 to which the present invention can be applied will be described with reference to FIG. 1 . As shown in FIG. 1 , the automatic transmission 3 suitable for a vehicle of FF type (front engine, front drive) has an input shaft 8 of the automatic transmission that can be connected to an engine (not shown) and is equipped with a torque converter 4 and an automatic speed change mechanism 5 centering on the axial direction of the input shaft 8 .

The torque converter 4 has a pump impeller 4 a connected to the input shaft 8 of the automatic transmission 3 , and a turbine runner 4 b to which the rotation of the pump impeller 4 a is transmitted via a working fluid. The turbine runner 4 b is connected to an input shaft 10 of the automatic speed change mechanism 5 disposed coaxial with the input shaft 8 . The torque converter 4 includes a lockup clutch 7 , and when the lockup clutch 7 is engaged, the rotation of the input shaft 8 of the automatic transmission 3 is transmitted directly to the input shaft 10 of the automatic speed change mechanism 5 .

The automatic speed change mechanism 5 includes a planetary gear SP and a planetary gear unit PU on the input shaft 10 . The planetary gear SP includes a sun gear S 1 , a carrier CR 1 and a ring gear R 1 , and on the carrier CR 1 , the planetary gear SP has a pinion P 1 to mesh with the sun gear S 1 and the ring gear R 1 , and it is a so-called single pinion planetary gear.

The planetary gear unit PU has a sun gear S 2 , a sun gear S 3 , a carrier CR 2 , and a ring gear R 2 as four rotating elements, and on the carrier CR 2 , the planetary gear unit PU has a long pinion PL to mesh with the sun gear S 2 and the ring gear R 2 , and a short pinion PS to mesh with the sun gear S 3 in the intermeshing form, and it is a so-called Ravigneaux type planetary gear.

The sun gear S 1 of the planetary gear SP is connected and held stationary to a boss portion (not shown) integrally fixed to a transmission case 9 . The ring gear R 1 has the same rotation (hereinafter called “input rotation”) as that of the input shaft 10 . The carrier CR 1 has decelerated rotation in which input rotation is decelerated by the fixed sun gear S 1 and the ring gear R 1 of the input rotation and connected to a clutch C- 1 (first friction engagement element) and a clutch C- 3 (third friction engagement element).

The sun gear S 2 of the planetary gear unit PU is connected to a brake B- 1 , which is a band brake, and can be fixed to the transmission case 9 , and is connected to the clutch C- 3 , and the decelerated rotation of the carrier CR 1 can be input via the clutch C- 3 . The sun gear S 3 is connected to the clutch C- 1 , and the decelerated rotation of the carrier CR 1 can be input.

The carrier CR 2 is connected to a clutch C- 2 (second friction engagement element) to which the rotation of the input shaft 10 is input, and the input rotation can be input via the clutch C- 2 . Further, the carrier CR 2 is connected to a one-way clutch F- 1 and a brake B- 2 , and the rotation in one direction is restricted with respect to the transmission case 9 via the one-way clutch F- 1 , and the rotation can be fixed via the brake B- 2 . The ring gear R 2 is connected to a counter gear 11 , and the counter gear 11 is connected to driving wheels via a counter shaft and a differential device (which are not shown).

Operation of Each Shift Speed in Automatic Transmission

Based on the above structure, the operation of the automatic speed change mechanism 5 will now be described with reference to FIGS. 1 , 2 , and 3 . In a velocity diagram shown in FIG. 3 , the vertical axis direction indicates the rotational speeds of the respective rotating elements (respective gears) and the horizontal axis direction corresponds to the gear ratio of the rotating elements. In the portion of the planetary gear SP in the velocity diagram, the vertical axes correspond to the sun gear S 1 , the carrier CR 1 and the ring gear R 1 sequentially from the left side in FIG. 3 . In the portion of the planetary gear unit PU of the velocity diagram, the vertical axes correspond to the sun gear S 3 , the ring gear R 2 , the carrier CR 2 and the sun gear S 2 sequentially from the right side in FIG. 3 .

In the D (drive) range, for example, at a forward first speed (1ST), the clutch C- 1 and the one-way clutch F- 1 are engaged as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 is input to the sun gear S 3 via the clutch C- 1 , the rotation of the carrier CR 1 being decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation. The rotation of the carrier CR 2 is restricted to one direction (normal rotation direction), i.e., the reverse rotation of the carrier CR 2 is prevented resulting in a fixed state. Then, the decelerated rotation input to the sun gear S 3 is output to the ring gear R 2 via the fixed carrier CR 2 , and the normal rotation as the forward first speed is output from the counter gear 11 .

When the engine brake is applied (coasting), the brake B- 2 is locked and the carrier CR 2 is fixed, and in the form of preventing the normal rotation of the carrier CR 2 , the state of the forward first speed is maintained. At the forward first speed, the reverse rotation of the carrier CR 2 is prevented by the one-way clutch F- 1 and the normal rotation is made possible. Therefore, when the non-running range is changed to the running range, for example, the forward first speed can be smoothly achieved through automatic engaging of the one-way clutch F- 1 .

At a forward second speed (2ND), the clutch C- 1 is engaged and the brake B- 1 is locked as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation is input to the sun gear S 3 via the clutch C- 1 . When the brake B- 1 is locked, the rotation of the sun gear S 2 is fixed. Then, the rotation of the carrier CR 2 is decelerated to be lower than that of the sun gear S 3 , and the decelerated rotation input to the sun gear S 3 is output to the ring gear R 2 via the carrier CR 2 , and the normal rotation as the forward second speed is output from the counter gear 11 .

At a forward third speed (3RD), the clutch C- 1 and clutch C- 3 are engaged as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation is input to the sun gear S 3 via the clutch C- 1 . When the clutch C- 3 is engaged, the decelerated rotation of the carrier CR 1 is input to the sun gear S 2 . That is, since the decelerated rotation of the carrier CR 1 is input to the sun gear S 2 and sun gear S 3 , the planetary gear unit PU is brought into a directly connected state of the decelerated rotation, and the decelerated rotation is output without change to the ring gear R 2 , and the normal rotation as the forward third speed is output from the counter gear 11 .

At a forward fourth speed (4TH), the clutch C- 1 and the clutch C- 2 are engaged as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation is input to the sun gear S 3 via the clutch C- 1 . Further, the input rotation is input to the carrier CR 2 due to the engagement of the clutch C- 2 . Then, due to the decelerated rotation input to the sun gear S 3 and the input rotation input to the carrier CR 2 , a decelerated rotation higher than the forward third speed occurs and is output to the ring gear R 2 , and the normal rotation as the forward fourth speed is output from the counter gear 11 .

At a forward fifth speed (5TH), the clutch C- 2 and clutch C- 3 are engaged as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation is input to the sun gear S 2 via the clutch C- 3 . Further, the input rotation is input to the carrier CR 2 due to the engagement of the clutch C- 2 . Then, due to the decelerated rotation input to the sun gear S 2 and the input rotation input to the carrier CR 2 , an accelerated rotation slightly higher than the input rotation occurs and is output to the ring gear R 2 , and the normal rotation as the forward fifth speed is output from the counter gear 11 .

At a forward sixth speed (6TH), the clutch C- 2 is engaged and the brake B- 1 is locked as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the input rotation is input to the carrier CR 2 due to the engagement of the clutch C- 2 . Further, the rotation of the sun gear S 2 is fixed by the lock of the brake B- 1 . Due to the fixed sun gear S 2 , the input rotation of the carrier CR 2 becomes an accelerated rotation higher than the forward fifth speed and is output to the ring gear R 2 , and the normal rotation as the forward sixth speed is output from the counter gear 11 .

At a reverse first speed (REV), the clutch C- 3 is engaged and the brake B- 2 is locked as shown in FIG. 2 . Then, as shown in FIG. 1 and FIG. 3 , the rotation of the carrier CR 1 decelerated by the fixed sun gear S 1 and the ring gear R 1 of input rotation is input to the sun gear S 2 via the clutch C- 3 . Further, the rotation of the carrier CR 2 is fixed by the lock of the brake B- 2 . Then, the decelerated rotation input to the sun gear S 2 is output to the ring gear R 2 via the fixed carrier CR 2 , and the reverse rotation as the reverse first speed is output from the counter gear 11 .

In P (parking) range and N (neutral) range, for example, the clutch C- 1 , the clutch C- 2 , and the clutch C- 3 are released. Then, disconnected state occurs between the carrier CR 1 and the sun gear S 2 and the sun gear S 3 , i.e., between the planetary gear SP and the planetary gear unit PU, and also the disconnected state occurs between the input shaft 10 and the carrier CR 2 . This disconnects power transmission between the input shaft 10 and the planetary gear unit PU, i.e., the power transmission between the input shaft 10 and the counter gear 11 is disconnected.

Outline Structure of Hydraulic Control Device

A hydraulic control device 1 1 for the automatic transmission according to the present invention will now be described. First, the generating portions of line pressure, secondary pressure, modulator pressure and range pressure, whose illustration is omitted, in the hydraulic control device 1 1 are outlined. Since these generating portions of line pressure, secondary pressure, modulator pressure and range pressure are similar to those in an ordinary hydraulic control device for an automatic transmission and well known, they are briefly described.

This hydraulic control device 1 1 includes an oil pump, a manual shift valve, a primary regulator valve, a secondary regulator valve, a solenoid modulator valve, and a linear solenoid valve whose illustration is omitted. When the engine is started, the oil pump that is rotatably and drivingly connected to the pump impeller 4 a of the torque converter 4 is driven in accordance with the rotation of the engine, thereby generating a hydraulic pressure in the form of sucking up the oil via a strainer from an oil pan not illustrated.

The hydraulic pressure generated by the oil pump is regulated to a line pressure P L while the discharge thereof is regulated by the primary regulator valve, based on a signal pressure P SLT of the linear solenoid valve that is regulated and output in accordance with the throttle opening. This line pressure P L is supplied to the manual shift valve (range switching valve), the solenoid modulator valve, and a linear solenoid valve SLC 3 described later in detail. The line pressure P L supplied to the solenoid modulator valve is regulated to a modulator pressure P MOD that is made approximately constant by the valve. This modulator pressure P MOD is supplied as an original pressure to the linear solenoid valve and solenoid valves S 11 and S 12 described later in detail.

The pressure discharged from the primary regulator valve is regulated to a secondary pressure P SEC while the discharge thereof is further regulated by the secondary regulator valve, for example. The secondary pressure P SEC is supplied to a lubricating oil passage and an oil cooler, for example, and also to the torque converter 4 and is also used for controlling the lockup clutch 7 .

The manual shift valve (not illustrated) has a spool to be mechanically (or electrically) driven to a shift lever provided at the driver's seat (not illustrated), and the position of the spool is changed in accordance with the shift range (e.g. P, R, N, and D) selected by the shift lever, thereby setting the output state or non-output state (drain) of the input line pressure P L .

In detail, if the D range is set through the operation of the shift lever, an input port to which the line pressure P L is input and a forward range pressure output port are connected based on the position of the spool, and from the forward range pressure output port, the line pressure P L is output as a forward range pressure (D range pressure) P D . If the R (reverse) range is set through the operation of the shift lever, the input port and a reverse range pressure output port are connected based on the position of the spool, and from the reverse range pressure output port, the line pressure P L is output as a reverse range pressure (R range pressure) P REV . If the P range or the N range is set through the operation of the shift lever, cutoff is made between the input port and the forward range pressure output port or the reverse range pressure output port by the spool, and the forward range pressure output port or the reverse range pressure output port is connected to a drain port. That is, the D range pressure P D or the R range pressure P REV is drained, resulting in the non-output state.

Detailed Structure of Shift Control Portion of Hydraulic Control Device

The portion mainly performing shift control in the hydraulic control device 1 1 according to the present invention will now be described with reference to FIG. 4 . In the present embodiment, the right half position and the left half position shown in FIG. 4 are called a “right half position” and a “left half position”, respectively, to describe the spool position.

This hydraulic control device 1 1 includes four linear solenoid valves SLC 1 , SLC 2 , SLC 3 , and SLB 1 to directly supply the output pressure regulated as an engaging pressure to five hydraulic servos in total: a hydraulic servo 41 of the clutch C- 1 , a hydraulic servo 42 of the clutch C- 2 , a hydraulic servo 43 of the clutch C- 3 , a hydraulic servo 44 of the brake B- 1 , and a hydraulic servo 45 of the brake B- 2 . The hydraulic control device 1 1 also includes the solenoid valve S 11 , the solenoid valve S 12 , a first clutch apply relay valve 21 , a second clutch apply relay valve 22 , a C- 2 relay valve 23 , and a B- 2 relay valve 24 , for example, as portions to achieve the limp-home function, and to switch the output pressure of the linear solenoid valve SLC 2 to the hydraulic servo 42 of the clutch C- 2 or the hydraulic servo 45 of the brake B- 2 .

To an oil passage a 1 , an oil passage a 4 , and an oil passage a 5 shown in FIG. 4 , the forward range pressure output port (not illustrated) of the manual shift valve is connected so that the forward range pressure P D can be input. To an oil passage 1 , the reverse range pressure output port (not illustrated) of the manual shift valve is connected so that the reverse range pressure P REV can be input. To an oil passage d, the line pressure P L from the primary regulator valve (not illustrated) is input. Further, to an oil passage g 1 , the modulator pressure P MOD from the modulator valve (not illustrated) is input.

Among the oil passages, the oil passage a 1 is connected via an oil passage a 2 to an input port 21 e of the first clutch apply relay valve 21 to be detailed later, and is provided with a check valve 50 and an orifice 60 . The oil passage a 1 is connected to an accumulator 30 via an oil passage a 3 and is also connected to the linear solenoid valve SLC 1 . The accumulator 30 has a case 30 c , a piston 30 b disposed inside the case 30 c , a spring 30 s to energize the piston 30 b , and an oil chamber 30 a formed between the case 30 c and the piston 30 b.

The linear solenoid valve (first solenoid valve) SLC 1 is of a normal close type that is placed in the non-output state during non-energizing, and has an input port SLC 1 a to input the forward range pressure P D via the oil passage a 1 and an output port SLC 1 b to adjust the forward range pressure P D and output a controlled pressure (first operating hydraulic pressure) P SLC1 as an engaging pressure P C1 to the hydraulic servo 41 . That is, the linear solenoid valve SLC 1 is so structured that it cuts off the input port SLC 1 a and the output port SLC 1 b to get into the non-output state during non-energizing, and during energizing based on a command value from a control unit (ECU) not illustrated, it increases the amount (amount of opening) to communicate the input port SLC 1 a with the output port SLC 1 b in accordance with the command value so that it can output the engaging pressure P C1 in accordance with the command value. The output port SLC 1 b of the linear solenoid valve SLC 1 is connected to an input port 22 c of the second clutch apply relay valve 22 described later via an oil passage b 1 .

On the other hand, the linear solenoid valve (second solenoid valve) SLC 2 is of a normal open type that gets into the output state during non-energizing, and has an input port SLC 2 a to input the forward range pressure P D via the oil passage a 4 , etc. and an output port SLC 2 b to adjust the forward range pressure P D and output a controlled pressure (second operating hydraulic pressure) P SLC2 as an engaging pressure P C2 (or engaging pressure P B2 ) to the hydraulic servo 42 . In other words, the linear solenoid valve SLC 2 gets into an output state with the input port SLC 2 a and the output port SLC 2 b communicated during non-energizing, and during energizing based on a command value from the control unit (ECU) not illustrated, the linear solenoid valve SLC 2 decreases the amount (or reduce the amount of opening) to communicate the input port SLC 2 a with the output port SLC 2 b in accordance with the command value, that is, it is so structured that it can output the engaging pressure P C2 (or P B2 ) in accordance with the command value. The linear solenoid valve SLC 2 is connected to an input port 22 f of the second clutch apply relay valve 22 described later via an oil passage c 1 .

The linear solenoid valve (third solenoid valve) SLC 3 is of a normal open type that gets into the output state during non-energizing, and has an input port SLC 3 a to input the line pressure P L via the oil passage d, etc., and an output port SLC 3 b to adjust the line pressure P L and output a controlled pressure (third operating hydraulic pressure) P SLC3 as an engaging pressure P C3 to the hydraulic servo 43 . That is, the linear solenoid valve SLC 3 gets into an output state with the input port SLC 3 a and the output port SLC 3 b communicated during non-energizing, and during energizing based on a command value from the control unit (ECU) not illustrated, the linear solenoid valve SLC 3 decreases the amount (reduce the amount of opening) to communicate the input port SLC 3 a with the output port SLC 3 b in accordance with the command value so that it can output the engaging pressure P C3 in accordance with the command value. The output port SLC 3 b of the linear solenoid valve SLC 3 is connected to the hydraulic servo 43 of the clutch C- 3 via an oil passage e 1 . The oil passage e 1 is provided with a check valve 53 and an orifice 63 , and via an oil passage e 2 , an oil chamber 33 a of a C- 3 damper 33 is connected thereto. Since the C- 3 damper 33 has the same structure as that of the accumulator 30 and is an ordinary damper, its detailed explanation is omitted.

The linear solenoid valve SLB 1 is of a normal close type that gets into the non-output state during non-energizing, and has an input port SLB 1 a to input the forward range pressure P D via the oil passage a 5 , etc. and an output port SLB 1 b to adjust the forward range pressure P D and output a controlled pressure P SLB1 as an engaging pressure P B1 to the hydraulic servo 44 . That is, the linear solenoid valve SLB 1 cuts off the input port SLB 1 a and the output port SLB 1 b to get into the non-output state during non-energizing, and during energizing based on a command value from the control unit (ECU) not illustrated, it increases the amount (amount of opening) to communicate the input port SLB 1 a with the output port SLB 1 b in accordance with the command value so that it can output the engaging pressure P B1 in accordance with the command value. The output port SLB 1 b of the linear solenoid valve SLB 1 is connected to the hydraulic servo 44 of the brake B- 1 via an oil passage f 1 . The oil passage f 1 is provided with a check valve 54 and an orifice 64 , and via an oil passage f 2 , an oil chamber 34 a of a B- 1 damper 34 is connected thereto.

The solenoid valve (fourth solenoid valve) S 11 is of a normal open type that gets into the output state during non-energizing, and has an input port S 1 a to input the modulator pressure P MOD via the oil passages g 1 and an oil passage g 2 , and an output port S 1 b to output the modulator pressure P MOD approximately as it is as a signal pressure P S1 during non-energizing (i.e., during OFF). The output port S 1 b is connected to an oil chamber 21 a of the first clutch apply relay valve 21 via an oil passages h 1 , h 2 . Further, via oil passages h 1 , h 3 , the output port S 1 b is connected to an oil chamber 22 a of the second clutch apply relay valve 22 , and via an oil passage h 4 , it is connected to an input port 24 c of the B- 2 relay valve 24 .

The solenoid valve S 12 is of a normal close type that gets into the non-output state during non-energizing, and has an input port S 2 a to input the modulator pressure P MOD via the oil passages g 1 and an oil passage g 3 , and an output port S 2 b to output the modulator pressure P MOD approximately as it is as a signal pressure P S2 during energizing (i.e., during ON). The output port S 2 b is connected to an oil chamber 24 a of the B- 2 relay valve 24 via an oil passage i.

The first clutch apply relay valve (preliminary shift speed switching valve) 21 has two spools 21 p and 21 q (first spool), a spring 21 s (first biasing device) to bias the spool 21 p upward in the figure, and a spring 21 t to bias the spools 21 p and 21 q in a direction to separate them, and also has the oil chamber 21 a at the upper part in the figure of the spool 21 q , an oil chamber 21 d at the lower part in the figure of the spool 21 p , an oil chamber 21 c between the spools 21 p and 21 q , and an oil chamber 21 b (first oil chamber) formed due to a diameter difference (difference in pressure receiving area) of the land portion of the spool 21 q , and furthermore, it has the input port 21 e , an input port 21 f , an input port 21 g , an input port 21 h , an output port 21 i , an output port 21 j , and a drain port EX.

The first clutch apply relay valve 21 is so structured that when the spools 21 p , 21 q are set to the left half position (high speed side position), the input port 21 e and the output port 21 j are communicated and the input port 21 e and the output port 21 i are disconnected, and when they are set to the right half position (low speed side position), the input port 21 e and the output port 21 i are communicated and the output port 21 j and the drain port EX are communicated. When the spool 21 p is set to the left half position, the input port 21 h is disconnected, and when the spool 21 q is set to the right half position, the input port 21 g is disconnected.

As described above, the oil chamber 21 a is connected to the output port S 1 b of the solenoid valve S 11 via the oil passages h 1 , h 2 , and the oil chamber 21 b is connected to an output port 22 i of the second clutch apply relay valve 22 described later via an oil passage b 4 from the input port 21 f . To the input port 21 e , the forward range pressure P D is input via the oil passages a 1 , a 2 . The output port 21 j that is communicated with the input port 21 e when the spool 21 p is at the left half position is connected to an input port 22 h of the second clutch apply relay valve 22 via an oil passage j. The output port 21 i that is communicated with the input port 21 e when the spool 21 p is at the right half position is connected to the input port 21 g via oil passages k 1 , k 2 and to the input port 21 h via oil passages k 1 , k 2 , k 3 . That is, the output port 21 i is connected to the oil chamber 21 c regardless of the position of the spools 21 p , 21 q . The output port 21 i is connected to an input port 22 e of the second clutch apply relay valve 22 described later via the oil passage k 1 . To the oil chamber 21 d , an output port 23 c of the C- 2 relay valve 23 is connected via an oil passage c 5 , and the oil passage c 5 is provided with a check valve 55 and an orifice 65 .

The second clutch apply relay valve (hydraulic pressure supply switching valve) 22 has a spool 22 p (second spool) and a spring 22 s (second biasing device) to bias the spool 22 p upward in the figure and also has the oil chamber 22 a (second oil chamber) at the upper part in the figure of the spool 22 p and an oil chamber 22 b at the lower part in the figure of the spool 22 p . Further, the second clutch apply relay valve 22 has the input port 22 c , an output port 22 d , the input port 22 e , the input port 22 f , an output port 22 g , the input port 22 h , and the output port 22 i.

The second clutch apply relay valve 22 is so structured that when the spool 22 p is set to the left half position (normal position), the input port 22 c and the output port 22 d and the output port 22 i are communicated and the input port 22 f and the output port 22 g are communicated, and the input port 22 e and the input port 22 h are disconnected; and when the spool 22 p is set to the right half position (failure position), the input port 22 e and the output port 22 d are communicated and the input port 22 h and the output port 22 g are communicated, and the input port 22 c and the output port 22 i and the input port 22 f are disconnected.

As described above, the oil chamber 22 a is connected to the output port S 1 b of the solenoid valve S 11 via the oil passages h 1 , h 3 , and connected to the input port 24 c of the B- 2 relay valve 24 described later via the oil passage h 4 . The input port 22 c is connected to the output port SLC 1 b of the linear solenoid valve SLC 1 via the oil passage b 1 . The output port 22 d that is communicated with the input port 22 c when the spool 22 p is set to the left half position is connected to the hydraulic servo 41 of the clutch C- 1 via an oil passage b 2 . The oil passage b 2 is provided with a check valve 51 and an orifice 61 , and via an oil passage b 3 , an oil chamber 31 a of a C- 1 damper 31 is connected thereto. The output port 22 i that is communicated with the input port 22 c when the spool 22 p is set to the left half position is connected to the input port 21 f of the first clutch apply relay valve 21 via the oil passage b 4 , and is connected to the oil chamber 22 b via oil passages b 4 , b 5 . On the other hand, the input port 22 f is connected to the output port SLC 2 b of the linear solenoid valve SLC 2 via the oil passage c 1 , and the input port 22 h is connected to the output port 21 j of the first clutch apply relay valve 21 via the oil passage (second oil passage) j. The output port 22 g that is communicated with the input port 22 f when the spool 22 p is set to the left half position and communicated with the input port 22 h when the spool 22 p is set to the right half position is connected to an input port 23 b of the C- 2 relay valve 23 described later via an oil passage c 2 . The oil passage c 2 is provided with a check valve 52 and an orifice 62 and via an oil passage c 4 , an oil chamber 32 a of a C 2 -B 2 damper 32 is connected thereto.

The C- 2 relay valve 23 has a spool 23 p and a spring 23 s to bias the spool 23 p upward in the figure, and also has an oil chamber 23 a at the upper part in the figure of the spool 23 p , and furthermore, it has the input port 23 b , the output port 23 c , an output port 23 d , an output port 23 e and a drain port EX.

The C- 2 relay valve 23 is so structured that, when the spool 23 p is set to the left half position, the input port 23 b and the output port 23 c and the output port 23 e are communicated and the output port 23 d and the drain port EX are communicated, and when the spool 23 p is set to the right half position, the input port 23 b and the output port 23 d are communicated and the output port 23 c and the output port 23 e and the drain port EX are communicated.

The oil chamber 23 a is connected to an output port 24 b of the B- 2 relay valve 24 described later via an oil passage h 5 . The input port 23 b is connected to the output port 22 g of the second clutch apply relay valve 22 via the oil passage c 2 . The output port 23 e that is communicated with the input port 23 b when the spool 23 p is at the left half position is connected to the hydraulic servo 42 of the clutch C- 2 via an oil passage c 3 . The output port 23 c that is communicated with the input port 23 b when the spool 23 p is at the left half position is connected to the oil chamber 21 d of the first clutch apply relay valve 21 via the oil passage c 5 . The oil passage c 5 is provided with the check valve 55 and the orifice 65 . The output port 23 d that is communicated with the input port 23 b when the spool 23 p is at the right half position is connected to an input port 24 e of the B- 2 relay valve 24 via an oil passage m.

The B- 2 relay valve 24 has a spool 24 p , and a spring 24 s to bias the spool 24 p upward in the figure, and also has the oil chamber 24 a at the upper part in the figure of the spool 24 p . Further, the B- 2 relay valve 24 has the output port 24 b , the input port 24 c , an input port 24 d , the input port 24 e , an output port 24 f , an output port 24 g , and a drain port EX.

The B- 2 relay valve 24 is so structured that, when the spool 24 p is set to the left half position, the input port 24 d and the output port 24 f and the output port 24 g are communicated and the output port 24 b and the drain port EX are communicated, and the input port 24 c is disconnected; and when the spool 24 p is set to the right half position, the input port 24 c and the output port 24 b are communicated and the input port 24 e and the output port 24 g are communicated, and the input port 24 d and the drain port EX are disconnected.

The oil chamber 24 a is connected to the output port S 2 b of the solenoid valve S 12 via an oil passage i. The input port 24 d is connected to the reverse range pressure output port (not illustrated) of the manual shift valve to which the reverse range pressure P REV is output via an oil passage i. The input port 24 e is connected to the output port 23 d of the C- 2 relay valve 23 via the oil passage m. The output port 24 g that is communicated with the input port 24 d when the spool 24 p is at the left half position and that is communicated with the input port 24 e when the spool 24 p is at the right half position is connected to the hydraulic servo 45 of the brake B- 2 via an oil passage n. That is, the hydraulic servo 45 of the brake B- 2 is connected to the reverse range pressure output port (not illustrated) of the manual shift valve, or to the output port SLC 2 b of the linear solenoid valve SLC 2 . As described above, the input port 24 c is connected to the output port S 1 b of the solenoid valve S 11 via the oil passage h 4 , the oil chamber 22 a of the second clutch apply relay valve 22 , and the oil passages h 1 , h 3 . The output port 24 b is communicated with the input port 24 c when the spool 24 p is at the right half position is connected to the oil chamber 23 a of the C- 2 relay valve 23 via the oil passage h 5 . The output port 24 f that is communicated with the input port 24 d when the spool 24 p is at the left half position is connected to the oil chamber of the primary regulator valve via an oil passage (not illustrated), and the line pressure P L is raised during reverse travel by having the reverse range pressure P REV work on the primary regulator valve.

Operation of Hydraulic Control Device

Then, description is made of the action of the hydraulic control device 1 1 according to the present embodiment.

If, for example, the ignition is switched ON by the driver, the hydraulic control for this hydraulic control device 1 1 is started. If the selected position of the shift lever is P range or N range, the normal type linear solenoid valve SLC 2 , the linear solenoid valve SLC 3 and the solenoid valve S 11 are energized by electric command of the control unit not illustrated and the respective input ports and output ports are disconnected. Then, if the engine is started, a hydraulic pressure is generated by the rotation of the oil pump (not illustrated) based on the engine rotation, and the hydraulic pressure is regulated to a line pressure P L and a modulator pressure P MOD , respectively, by the primary regulator valve and the solenoid modulator valve and output, and the line pressure P L is input to the input port of the manual shift valve not illustrated and to the input port SLC 3 a of the linear solenoid valve SLC 3 via the oil passage d, and the modulator pressure P MOD is input to the input ports S 1 a , S 2 a of the solenoid valves S 11 , S 12 via the oil passages g 1 , g 2 , g 3 .

Then, if the driver changes the shift lever from the N range position to the D range position, a forward range pressure P D is output to the oil passages a 1 , a 4 , a 5 from the forward range pressure output port of the manual shift valve. The forward range pressure P D is input to the linear solenoid valve SLC 1 via the oil passage a 1 , the linear solenoid valve SLC 2 via the oil passage a 4 , the linear solenoid valve SLB 1 via the oil passage a 5 , and the first clutch apply relay valve 21 via the oil passages a 1 , a 2 , respectively.

The oil passage a 1 is provided with the check valve 50 and the orifice 60 , and since the check valve 50 is opened by the forward range pressure P D , the supply of the forward range pressure P D to the linear solenoid valve SLC 1 becomes quicker than in discharge. The forward range pressure P D supplied to the oil passage a 1 is input to the oil chamber 30 a of the accumulator 30 via the oil passage a 3 . The accumulator 30 accumulates the forward range pressure P D to be supplied to the linear solenoid valve SLC 1 .

The first clutch apply relay valve 21 where the forward range pressure P D is input from the oil passage a 2 is shifted to the left half position by the biasing force of the spring 21 s at the beginning of switching to D range (at the beginning of N-D shifting) because the signal pressure P S1 is not output with the solenoid valve S 11 set to ON, and the forward range pressure P D is output to the oil passage j from the output port 21 j . However, since the signal pressure P S1 is not output with the solenoid valve S 11 set to ON, the input port 22 h is disconnected in the second clutch apply relay valve 22 , which is shifted to the left half position by the biasing force of the spring 22 s.

Then, if the forward first speed is judged by the control unit, the linear solenoid valve SLC 1 is switched ON by electrical control of the control unit, and the forward range pressure P D input to the input port SLC 1 a is regulated and controlled, and the controlled pressure P SLC1 is gradually increased as the engaging pressure P C1 and output from the output port SLC 1 b . The controlled pressure P SLC1 (engaging pressure P C1 ) is input to the input port 22 c of the second clutch apply relay valve 22 via the oil passage b 1 .

The second clutch apply relay valve 22 set to the left half position outputs the controlled pressure P SLC1 input to the input port 22 c , from the output port 22 i and also from the output port 22 d . The controlled pressure P SLC1 output from the output port 22 i is input to the oil chamber 22 b via the oil passages b 4 , b 5 , and locks the second clutch apply relay valve 22 to the left half position, and is input to the oil chamber 21 b of the first clutch apply relay valve 21 via the oil passage b 4 , and pushes the spools 21 p , 21 q to the lower part in the figure against the biasing force of the spring 21 s , and switches the first clutch apply relay valve 21 to the right half position.

The first clutch apply relay valve 21 , with the spools 21 p , 21 q switched to the right half position, pushes the spool 21 q to the lower part in the figure against the biasing force of the spring 21 t by means of the controlled pressure P SLC1 output from the output port 22 i of the second clutch apply relay valve 22 . However, since the forward range pressure P D input from the input port 21 e is output as a first preliminary hydraulic pressure P DC1 from the output port 21 i and is input to the oil chamber 21 c via the oil passages k 1 , k 2 , k 3 and the input port 21 h , the spool 21 q is switched to the upper part in the figure by means of the hydraulic pressure working on the oil chamber 21 c and the biasing force of the spring 21 t . That is, the spool 21 p and spool 21 q are locked in a state where they are separated from each other. The first preliminary hydraulic pressure P DC1 (forward range pressure P D ) input to the input port 22 e of the second clutch apply relay valve 22 from the oil passage k 1 is blocked in the input port 22 e.

The controlled pressure P SLC1 input to the input port 22 c of the second clutch apply relay valve 22 from the linear solenoid valve SLC 1 , as described above, is output as the engaging pressure P C1 to the hydraulic servo 41 via the oil passage b 2 from the output port 22 d , and the clutch C- 1 is engaged. Thus, together with the engaging of the one-way clutch F- 1 , the forward first speed is achieved.

The oil passage b 2 is provided with the check valve 51 and the orifice 61 . When the engaging pressure P C1 (controlled pressure P SLC1 ) is supplied to the hydraulic servo 41 , the check valve 51 is closed and the hydraulic pressure is slowly supplied only through the orifice 61 . When the engaging pressure P C1 is discharged from the hydraulic servo 41 , the check valve 51 is opened so that the engaging pressure P C1 is quickly discharged compared to when being supplied. Further, the engaging pressure P C1 supplied to the oil passage b 2 is input to the oil chamber 31 a of the C- 1 damper 31 via the oil passage b 3 . The C- 1 damper 31 prevents pulsation of the engaging pressure P C1 supplied to and discharged from the hydraulic servo 41 , and absorbs a surge pressure (rapid fluctuating pressure).

Operation in Engine Brake of Forward First Speed

If the engine brake of the forward first speed is judged by the control unit, the solenoid valve S 112 is switched ON and the solenoid valve S 11 is switched OFF by an electric command from the control unit and the linear solenoid valve SLC 2 is controlled in pressure. When the solenoid valve S 12 is switched ON, the modulator pressure P MOD input to the input port S 2 a via oil passages g 1 , g 3 is output as a signal pressure P S2 from the output port S 2 b and input to the oil chamber 24 a of the B- 2 relay valve 24 via the oil passage i. The spool 24 p is switched to the lower part in the figure against the biasing force of the spring 24 s , and the B- 2 relay valve 24 is set to the right half position.

When the solenoid valve S 11 is switched OFF, the modulator pressure P MOD input to the input port S 1 a via oil passages g 1 , g 2 is output as a signal pressure P S1 from the output port S 1 b , and is input to the oil chamber 21 a of the first clutch apply relay valve 21 via the oil passages h 1 , h 2 , the oil chamber 22 a of the second clutch apply relay valve 22 via the oil passages h 1 , h 3 , and the input port 24 c of the B- 2 relay valve 24 via the oil passage h 4 , and also to the oil chamber 23 a of the C- 2 relay valve 23 via the oil passage h 5 from the output port 24 b of the B- 2 relay valve 24 set to the right half position.

Consequently, the spool 23 p is switched to the lower part in the figure against the biasing force of the spring 23 s by means of the signal pressure P s1 input to the oil chamber 23 a , and the C- 2 relay valve 23 is set to the right half position. It should be noted that while the spool 21 q is switched to the lower part in the figure because of the signal pressure P S1 input to the oil chamber 21 a and the first clutch apply relay valve 21 is set to the right half position, the spool 21 p remains in the right half position as in the forward first speed without being specifically affected. While the signal pressure P S1 is input to the oil chamber 22 a in the second clutch apply relay valve 22 , the engaging pressure P C1 (controlled pressure P SLC1 ) of the oil chamber 22 b and the biasing force of the spring 22 s surpass. As a result, the spool 22 p remains to be locked in the left half position.

Then, when the linear solenoid valve SLC 2 is controlled in pressure, and the controlled pressure P SLC2 is output from the output port SLC 2 b , the controlled pressure P SLC2 is input to the input port 22 f of the second clutch apply relay valve 22 locked to the left half position via the oil passage c 1 , and is output as the engaging pressure P B2 to the oil passage c 2 from the output port 22 g.

The engaging pressure P B2 output to the oil passage c 2 is input to the input port 23 b of the C- 2 relay valve 23 set to the right half position, and is output from the output port 23 d . Furthermore, the engaging pressure P B2 is input to the input port 24 e of the B- 2 relay valve 24 set to the right half position via the oil passage m, and is output from the output port 24 g , and is input to the hydraulic servo 45 via the oil passage n, and the brake B- 2 is locked. Thus, together with the engaging of the clutch C- 1 , the engine brake of the forward first speed is achieved.

The oil passage c 2 is provided with the check valve 52 and the orifice 62 , and when the engaging pressure P B2 is supplied to the hydraulic servo 45 of the brake B- 2 , the check valve 52 is closed and the hydraulic pressure is slowly supplied through the orifice 62 only, and at the time of discharging to be described later, the check valve 52 is opened and the hydraulic pressure in the oil passage c 2 is quickly discharged. The engaging pressure P B2 supplied to the oil passage c 2 is input to the oil chamber 32 a of the C 2 -B 2 damper 32 via the oil passage c 4 , and the C 2 -B 2 damper 32 prevents pulsating of the engaging pressure P B2 supplied to and discharged from the hydraulic servo 45 , absorbs a surge pressure (rapid fluctuating pressure), etc.

If positive drive of the forward first speed is judged by the control unit or releasing of the engine brake state is judged, the solenoid valve S 12 is set to OFF and the solenoid valve S 11 to ON. Further, the linear solenoid valve SLC 2 is closed in the form of ON (energizing), and the controlled pressure P SLC2 as the engaging pressure P B2 is set to 0 and drained. The engaging pressure P B2 of the hydraulic servo 45 of the brake B- 2 is discharged through the drain port of the manual shift valve via the input port 24 d , an oil passage 1 , and the reverse range pressure output port (not illustrated) of the manual shift valve, because the B- 2 relay valve 24 is switched to the left half position when the solenoid valve S 12 is set to OFF. This makes quicker draining than the draining via the linear solenoid valve SLC 2 , and the brake B- 2 is quickly released. Note that the hydraulic pressure in the oil passage m is discharged from the drain port EX of the C- 2 relay valve 23 switched to the left half position, and the hydraulic pressure in the oil passages c 1 , c 2 is discharged from a drain port EX of the linear solenoid valve SLC 2 .

Operation in Forward Second Speed

Then, if the forward second speed is judged from the state of the forward first speed by the control unit, in a state where the solenoid valve S 11 is set to ON and the solenoid valve S 12 to OFF by the electrical command from the control unit as in the case of the forward first speed (except for engine brake), the pressure regulation control of the linear solenoid valve SLB 1 is performed while the pressure regulated state of the linear solenoid valve SLC 1 is maintained.

When the linear solenoid valve SLB 1 is controlled in pressure, the controlled pressure P SLB1 as the engaging pressure P B1 is output from the output port S LB1b and input to the hydraulic servo 44 via the oil passage f 1 , and the brake B- 1 is locked. Thus, together with the engaging of the clutch C- 1 , the forward second speed is achieved.

The oil passage f 1 is provided with the check valve 54 and the orifice 64 . When the engaging pressure P B1 is supplied to the hydraulic servo 44 of the brake B- 1 , the check valve 54 is closed and the hydraulic pressure is slowly supplied only through the orifice 64 . When the engaging pressure P B1 is discharged from the hydraulic servo 44 , the check valve 54 is opened so that the hydraulic pressure is quickly discharged compared to when being supplied. The engaging pressure P B1 supplied to the oil passage f 1 is input to the oil chamber 34 a of the B- 1 damper 34 via the oil passage f 2 . The B- 1 damper 34 prevents pulsation of the engaging pressure P B1 supplied to and discharged from the hydraulic servo 44 , and absorbs the surge pressure (rapid fluctuating pressure).

Operation in Forward Third Speed

Next, if the forward third speed is judged from the state of the forward second speed by the control unit, in a state where the solenoid valve S 11 is set to ON and the solenoid valve S 12 to OFF by the electric command from the control unit, the linear solenoid valve S LB1 is closed in the form of OFF and the pressure regulation control of the linear solenoid valve SLC 3 is performed, while the pressure regulated state of the linear solenoid valve SLC 1 is maintained.

First, by the pressure regulation control of the linear solenoid valve SLB 1 , the brake B- 1 is release-controlled. More specifically, the engaging pressure P B1 (controlled pressure P S1 ) of the hydraulic servo 44 of the brake B- 1 is discharge-controlled through the drain port EX of the linear solenoid valve SLB 1 via the oil passage f 1 , and the brake B- 1 is released. On the other hand, the linear solenoid valve SLC 3 is controlled in pressure from the state of being closed so that the controlled pressure P SLC3 becomes 0 after ON (energizing). The controlled pressure P SLC3 is output as the engaging pressure P C3 from the output port SLC 3 b , and is input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. Thus, together with the engaging of the clutch C- 1 , the forward third speed is achieved.

The oil passage e 1 is provided with the check valve 53 and the orifice 63 . When the engaging pressure P C3 is supplied to the hydraulic servo 43 of the clutch C- 3 , the check valve 53 is closed and the hydraulic pressure is slowly supplied only through the orifice 63 . When the engaging pressure P C3 is discharged from the hydraulic servo 43 , the check valve 53 is opened so that the hydraulic pressure is quickly discharged compared to when being supplied. Further, the engaging pressure P C3 supplied to the oil passage e 1 is input to the oil chamber 33 a of the C- 3 damper 33 via the oil passage e 2 . The C- 3 damper 33 prevents pulsation of the engaging pressure P C3 supplied to and discharged from the hydraulic servo 43 , and absorbs the surge pressure (rapid fluctuating pressure).

Operation in Forward Fourth Speed

If the forward fourth speed is judged from the state of the forward third speed by the control unit, in the state where the solenoid valve S 11 is set to ON and the solenoid valve S 12 to OFF by the electric command from the control unit, the linear solenoid valve SLC 3 is closed in the form of OFF and the pressure regulation control of the linear solenoid valve SLC 2 is performed, while the pressure regulated state of the linear solenoid valve SLC 1 is maintained.

First, by the pressure regulation control of the linear solenoid valve SLC 3 , the clutch C- 3 is release-controlled. More specifically, the engaging pressure P C3 (controlled pressure P SLC3 ) of the hydraulic servo 43 of the clutch C- 3 is discharge-controlled from the drain port EX of the linear solenoid valve SLC 3 via the oil passage e 1 , and the clutch C- 3 is released. On the other hand, the linear solenoid valve SLC 2 is controlled in pressure from the state of being closed so that the controlled pressure P SLC2 becomes 0 after ON (energizing). The controlled pressure P SLC2 is output as the engaging pressure P C2 from the output port SLC 2 b , and is input to the input port 22 f of the second clutch apply relay valve 22 via the oil passage c 1 .

Since the second clutch apply relay valve 22 , with the solenoid valve S 11 set to ON and the signal pressure P S1 not input to the oil chamber 22 a , is locked to the left half position by the engaging pressure P C1 input to the oil chamber 22 b , the controlled pressure P SLC2 (engaging pressure P C2 ) input to the input port 22 f is output from the output port 22 g as the engaging pressure P C2 . The engaging pressure P C2 output from the output port 22 g is input to the input port 23 b of the C- 2 relay valve 23 via the oil passage c 2 .

Since the C- 2 relay valve 23 , with the solenoid valve S 12 set to OFF, the B- 2 relay valve 24 set to the left half position, and the oil chamber 23 a and the oil passage h 5 placed in the drain state, is set to the left half position by the biasing force of the spring 23 s , the engaging pressure P C2 input to the input port 23 b is output from the output port 23 c , and is also output from the output port 23 e . The engaging pressure P C2 output from the output port 23 c is input to the oil chamber 21 d of the first clutch apply relay valve 21 via the oil passage c 5 , and the spool 21 p of the first clutch apply relay valve 21 is switched to the left half position and locked by the engaging pressure P C2 , together with the biasing force of the spring 21 s . At that time, the forward range pressure P D input to the input port 22 e via the oil passage k 1 is switched from the output port 21 i to output port 21 j , and is output as a second preliminary hydraulic pressure P DC2 to the oil passage j, however, blocked by the input port 22 h of the second clutch apply relay valve 22 . Since the first preliminary hydraulic pressure P DC1 (forward range pressure P D ) supplied to the oil passage k 1 is blocked, the supply of the forward range pressure P D as the lock pressure to the oil chamber 21 c via the oil passages k 2 , k 3 is released.

The oil passage c 5 is provided with the check valve 55 and the orifice 65 . When the engaging pressure P C2 is supplied to the oil chamber 21 d of the first clutch apply relay valve 21 , the check valve 55 is closed, and the hydraulic pressure is slowly supplied only through the orifice 65 . When the engaging pressure P C2 is discharged from the oil chamber 21 d , the check valve 55 is opened so that the hydraulic pressure is discharged more quickly than when being supplied.

The engaging pressure P C2 output from the output port 23 e of the C- 2 relay valve 23 is input to the hydraulic servo 42 via the oil passage c 3 , and the clutch C- 2 is engaged. Thus, together with the engaging of the clutch C- 1 , the forward fourth speed is achieved.

As described above, the oil passage c 2 is provided with the check valve 52 and the orifice 62 . In the same manner as in the case of the engine brake of the forward first speed, when the engaging pressure P C2 is supplied to the hydraulic servo 42 of the clutch C- 2 , the check valve 52 is closed and the hydraulic pressure is slowly supplied only through the orifice 62 . When the engaging pressure P C2 is discharged from the hydraulic servo 42 , the check valve 52 is opened so that the hydraulic pressure is discharged more quickly than when being supplied. The engaging pressure P C2 supplied to the oil passage c 2 is input to the oil chamber 32 a of the C 2 -B 2 damper 32 via the oil passage c 4 . The C 2 -B 2 damper 32 prevents pulsation of the engaging pressure P C2 supplied to and discharged from the hydraulic servo 42 , and absorbs the surge pressure (rapid fluctuating pressure).

Operation in Forward Fifth Speed

If the forward fifth speed is judged from the state of the forward fourth speed by the control unit, in a state where the solenoid valve S 11 is set to ON and the solenoid valve S 12 to OFF by the electrical command from the control unit, while the pressure regulated state of the linear solenoid valve SLC 2 is maintained, the linear solenoid valve SLC 1 is closed in the form of OFF, and the pressure regulation control of the linear solenoid valve SLC 3 is performed.

First, by the pressure regulation control of the linear solenoid valve SLC 1 , the clutch C- 1 is release-controlled. More specifically, the engaging pressure P C1 (controlled pressure P SLC1 ) of the hydraulic servo 41 of the clutch C- 1 is discharge-controlled from the drain port EX of the linear solenoid valve SLC 1 via the oil passages b 1 , b 2 , and the clutch C- 1 is released. On the other hand, in the same manner as in the case of the forward third speed, the linear solenoid valve SLC 3 is controlled in pressure from the state of being closed so that the controlled pressure P SLC3 becomes 0 after ON (energizing). The controlled pressure P SLC3 is output as the engaging pressure P C3 from the output port SLC 3 b , and is input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. Thus, together with the engaging of the clutch C- 2 , the forward fifth speed is achieved.

Operation in Forward Sixth Speed

If the forward sixth speed is judged from the state of the forward fifth speed by the control unit, in a state where the solenoid valve S 11 is set to ON and the solenoid valve S 12 to OFF by the electrical command from the control unit, the linear solenoid valve SLC 3 is closed in the form of ON (energizing) and the pressure regulation control of the linear solenoid valve SLB 1 is performed, while the pressure regulated state of the linear solenoid valve SLC 2 is maintained.

First, by the pressure regulation control of the linear solenoid valve SLC 3 , the clutch C- 3 is release-controlled. More specifically, the engaging pressure P C3 (controlled pressure P SLC3 ) of the hydraulic servo 43 of the clutch C- 3 is discharge-controlled from the drain port EX of the linear solenoid valve SLC 3 via the oil passage e 1 , and the clutch C- 3 is released. On the other hand, in the same manner as in the case of the forward second speed, the linear solenoid valve SLB 1 is switched ON (energizing) and controlled in pressure, from the state of being closed so that the controlled pressure P SLB1 becomes 0 after OFF. The controlled pressure P SLB1 is output as the engaging pressure P B1 from the output port SLB 1 b , and is input to the hydraulic servo 44 via the oil passage f 1 , and the brake B- 1 is engaged. Thus, together with the engaging of the clutch C- 2 , the forward sixth speed is achieved.

Operation in D-N

If a vehicle is decelerated by the driver, down-shifted in accordance with the vehicle speed, and stopped in the state of the forward first speed, and then if the shift lever is changed from the D range position to the N range position, the forward range pressure output port of the manual shift valve is disconnected with the input port and communicated with the drain port, that is, the forward range pressure P D is drained.

At the same time a shift lever sensor (not illustrated) detects that the shift lever is in the N range position, and if the N range is judged by the control unit in accordance with the shift lever position, the linear solenoid valve SLC 2 and the linear solenoid valve SLC 3 are set to ON (energized) and the linear solenoid valve SLB 1 to OFF, and these controlled pressures P SLC2 , P SLC3 , and P SLB1 are drained to 0 (non-output state). That is, the hydraulic pressures of the respective hydraulic servos 42 , 43 , 44 and 45 are drained, and the clutch C- 2 , the clutch C- 3 , the brake B- 1 and the brake B- 2 are released. The solenoid valve S 11 is maintained in the ON (energized) state, and the solenoid valve S 12 is maintained in the OFF state. That is, signal pressures P S1 , P S2 are not output from both the solenoid valves S 11 and S 12 .

If the clutch C- 1 is rapidly released, for example, releasing shock will occur. Therefore, the linear solenoid valve SLC 1 performs the pressure regulation control such that the controlled pressure P SLC1 is gradually reduced and finally the controlled pressure P SLC1 is drained to 0 (non-output state), thereby slowly releasing the clutch C- 1 . When this clutch C- 1 is also released, all clutch brakes of the automatic transmission 3 are released, resulting in a neutral state.

During the release control by the linear solenoid valve SLC 1 , the accumulator 30 connected to the input port SLC 1 a of the linear solenoid valve SLC 1 via the oil passage a 3 , etc. maintains the pressure by releasing a hydraulic pressure accumulated during the D range, to the oil passages a 1 , a 3 on the side of the linear solenoid valve SLC 1 rather than the orifice 60 . Thus, the slow release control of the clutch C- 1 by the linear solenoid valve SLC 1 is realized. This prevents the release shock from occurring when the D-N shift operation is performed from the forward first speed state.

Operation in Reverse First Speed

If the shift lever is moved to the R range position through the shift lever operation by the driver, the reverse range pressure P REV is output from the reverse range pressure output port of the manual shift valve, and the reverse range pressure P REV is input to the input port 24 d of the B- 2 relay valve 24 via the oil passage 1 , etc.

Further, if the shift lever sensor (not illustrated) detects that the shift lever is at the R range position, and the R range is judged as the shift lever position by the control unit, the solenoid valve S 11 is set to ON (energized) and maintained, and the solenoid valve S 12 is set to OFF and maintained. That is, since the signal pressure P S2 is not output, the B- 2 relay valve 24 is maintained at the left half position by the biasing force of the spring 24 s . By this, the reverse range pressure P REV input to the input port 24 c is supplied to the hydraulic servo 45 of the brake B- 2 via the output port 24 g and the oil passage n, and the brake B- 2 is engaged.

The pressure regulation control is performed by the control unit so that the linear solenoid valve SLC 3 gradually outputs the controlled pressure P SLC3 , which is output as the engaging pressure P C3 from the output port SLC 3 b and is input to the hydraulic servo 43 via the oil passage e 1 . That is, the clutch C- 3 is slowly engaged. Thus, together with the locking of the brake B- 2 , the reverse first speed is achieved.

Note that, when the R range is switched to the N range, in the same manner as in the case of the N range, the engaging pressure P B2 of the hydraulic servo 45 of the brake B- 2 is drained via the oil passage n, the B- 2 relay valve 24 , the oil passage 1 and the manual shift valve, and the engaging pressure P C3 of the hydraulic servo 43 of the clutch C- 3 is drained from the linear solenoid valve SLC 3 .

If the shift lever is moved to the R range position by the driver and if it is detected that the vehicle speed is more than a predetermined speed in the forward direction, the solenoid valve S 12 is switched ON by the control unit, and the ON state (energized state) of the linear solenoid valve SLC 3 is maintained. That is, the R range pressure P REV is blocked by the B- 2 relay valve 24 so that it will not be supplied to the hydraulic servo 45 of the brake B- 2 , and the engaging pressure P C3 (controlled pressure P SLC3 ) is not supplied to the hydraulic servo 43 of the clutch C- 3 . Thus, a so-called reverse inhibit function works, and the reverse first speed is prevented from being achieved.

Operation at Solenoid-All-Off Failure

Then, the operation at the solenoid-all-off failure in this hydraulic control device 1 1 will be described. If all the solenoid valves (linear solenoid valve SLC 1 , linear solenoid valve SLC 2 , linear solenoid valve SLC 3 , linear solenoid valve SLB 1 , solenoid valve S 11 , and solenoid valve S 12 ) OFF-fail (hereinafter called “all-off failure”) due to down, short-circuit, wire breakage, etc. of the control unit during the normal running with the shift lever position in the D range, the linear solenoid valve SLC 1 , the linear solenoid valve SLB 1 and the solenoid valve S 12 output no hydraulic pressure because they are of the normal close type. The linear solenoid valve SLC 2 , the linear solenoid valve SLC 3 and the solenoid valve S 11 output respective hydraulic pressures because they are of the normal open type.

During running at the forward first speed to the forward third speed when normal, the first clutch apply relay valve 21 has the spool 21 p locked to the right half position by the first preliminary hydraulic pressure P DC1 input to the oil chamber 21 c . For this reason, the first preliminary hydraulic pressure P DC1 is input to the input port 22 e of the second clutch apply relay valve 22 via the oil passage k 1 and is blocked by the second clutch apply relay valve 22 set to the left half position (normal position).

If all-off failure occurs from this state, the second clutch apply relay valve 22 is switched to the right half position (failure position) when the signal pressure P S1 output from the solenoid valve S 11 is input to the oil chamber 22 a via the oil passages h 1 , h 3 , and the first preliminary hydraulic pressure P DC1 input to the input port 22 e is output from the output port 22 d and input to the hydraulic servo 41 via the oil passage b 2 , and the clutch C- 1 is engaged. The pressure P SLC2 (engaging pressure P C2 ) output from the linear solenoid valve SLC 2 of the normal open type is blocked by the input port 22 f of the second clutch apply relay valve 22 switched to the right half position. With the linear solenoid valve SLC 3 of the normal open type, on the other hand, the line pressure P L input to the input port SLC 3 a is, approximately as it is, output as the engaging pressure P C3 from the output port SLC 3 b and input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. By this, the clutch C- 1 and the clutch C- 3 are engaged and the forward third speed is achieved (see FIG. 2 ). That is, the running state at the forward third speed is secured when the all-off failure occurs during the running at the forward first speed to the forward third speed.

During normal running at the forward fourth speed to the forward sixth speed, the controlled pressure P SLC2 (engaging pressure P C2 ) of the clutch C- 2 is input to the oil chamber 21 d of the first clutch apply relay valve 21 via the oil passage c 1 , the second clutch apply relay valve 22 , the oil passage c 2 , the C- 2 relay valve 23 , and the oil passage c 5 , and the spools 21 p , 21 q are locked to the left half position. Therefore, the second preliminary hydraulic pressure P DC2 output from the output port 21 j is input to the input port 22 h of the second clutch apply relay valve 22 via the oil passage j, and blocked by the second clutch apply relay valve 22 set to the left half position.

If all-off failure occurs from this state, the second clutch apply relay valve 22 is switched to the right half position when the signal pressure P S1 output from the solenoid valve S 11 is input to the oil chamber 22 a via the oil passages h 1 , h 3 , and the solenoid valve S 12 becomes OFF and the B- 2 relay valve 24 is not switched and is maintained at the left half position. Therefore, the oil passage h 4 is blocked, and since the signal pressure P S1 of the solenoid valve S 11 is not output to the oil passage h 5 , the C- 2 relay valve 23 is not switched and is maintained at the left half position. For this reason, the second preliminary hydraulic pressure P DC2 input to the input port 22 h of the second clutch apply relay valve 22 is output from the output port 22 g and input to the hydraulic servo 42 via the hydraulic pressure c 2 , the C- 2 relay valve 23 , and the oil passage c 3 , and the clutch C- 2 is engaged. The pressure P SLC2 (engaging pressure P C2 ) output from the linear solenoid valve SLC 2 of the normal open type is blocked by the input port 22 f of the second clutch apply relay valve 22 switched to the right half position. However, since the second preliminary hydraulic pressure P DC2 output to the oil passage c 2 is also output to the oil passage c 5 via the C- 2 relay valve 23 and input to the oil chamber 21 d of the first clutch apply relay valve 21 , the first clutch apply relay valve 21 is continuously locked to the left half position. With the linear solenoid valve SLC 3 normally opened, the line pressure P L input to the input port SLC 3 a is, approximately as it is, output as the engaging pressure P C3 from the output port SLC 3 b and input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. By this, the clutch C- 2 and the clutch C- 3 are engaged and the forward fifth speed is achieved (see FIG. 2 ). That is, the running state at the forward fifth speed is secured when the all-off failure occurs during running at the forward fourth speed to the forward-sixth speed.

When all-off failure occurs during normal running at the forward fourth speed to the forward sixth speed and if the vehicle is stopped and the shift lever is moved to the N range position, the manual shift lever not illustrated stops the output of the forward range pressure P D and drains. Particularly, the forward range pressure P D to the linear solenoid valve SLC 2 normally opened and to the input port 21 e of the first clutch apply relay valve 21 is drained. Then, the second preliminary hydraulic pressure P DC2 to the oil chamber 21 d input via the oil passages j, c 2 , c 5 is drained, and the lock by the second preliminary hydraulic pressure P DC2 is unlocked. From the solenoid valve S 11 normally opened, the signal pressure P S1 is continuously output. Therefore, the spools 21 p , 21 q of the first clutch apply relay valve 21 are switched to the right half position by the signal pressure P S1 input to the oil chamber 21 a.

In the state of N range when the all-off failure occurs, the line pressure P L serves as the original pressure, and the controlled pressure P SLC3 (engaging pressure P C3 ) that is almost the same as the line pressure P L is output from the linear solenoid valve SLC 3 that is normally opened. Therefore, the clutch C- 3 is in an engaged state. Even when the clutch C- 3 is engaged, the clutches C- 1 , C- 2 and the brakes B- 1 , B- 2 are in the released state, and even when decelerating rotation is input to the sun gear S 2 , the sun gear S 3 and the carrier CR 2 idle. Therefore, an approximately neutral state is established between the input shaft 10 and the counter gear 11 (see FIG. 1 ).

For example, if the driver moves the shift lever again to the D range position, the forward range pressure P D is output from the manual shift valve. The forward range pressure P D is input to the input port 21 e of the first clutch apply relay valve 21 switched to the right half position, and it is output as the first preliminary hydraulic pressure P DC1 from the output port 21 i to the oil passage k 1 , and input to the hydraulic servo 41 of the clutch C- 1 via the input port 22 e and the output port 22 d of the second clutch apply relay valve 22 at the right half position, and the oil passage b 2 , and the clutch C- 1 is engaged. That is, the same state as that at the all-off failure during the running at the forward first speed to the forward third speed occurs, and the forward third speed is secured. This enables restarting of the vehicle even after the vehicle temporarily stops after the all-off failure, and the limp-home function is secured.

With the hydraulic control device 1 1 according to the present invention, as described above, the clutches C- 1 , C- 2 , C- 3 are controlled such that they are freely engaged by the controlled pressures P SLC1 , P SLC2 , P SLC3 of the linear solenoid valves SLC 1 , SLC 2 , SLC 3 , respectively, during normal running. At all-off failure, the controlled pressure P SLC3 of the linear solenoid valve SLC 3 is supplied to the hydraulic servo 43 of the clutch C- 3 , and the output state of the first preliminary hydraulic pressure P DC1 or the second preliminary hydraulic pressure P DC2 is switched based on the engaged state of the clutch C- 2 by the first clutch apply relay valve 21 . In addition, by the second clutch apply relay valve 22 , the first preliminary hydraulic pressure P DC1 or the second preliminary hydraulic pressure P DC2 can be supplied to the hydraulic servo 41 of the clutch C- 1 or the hydraulic servo 42 of the clutch C- 2 , respectively. When the all-off failure occurs during running, this can achieve the forward third speed or the forward fifth speed in accordance with the shift speed before the occurrence of the all-off failure, with a structure equipped with only two valves, i.e., the first clutch apply relay valve 21 and the second clutch apply relay valve 22 , making it possible to achieve compactness and cost reduction.

At the forward fourth speed to the forward sixth speed during normal operation as described above, the controlled pressure P SLC2 of the linear solenoid valve SLC 2 is supplied as the engaging pressure P C2 to the hydraulic servo 42 of the clutch C- 2 , and also supplied to the oil chamber 21 d of the first clutch apply relay valve 21 . The spools 21 p , 21 q of the first clutch apply relay valve 21 are switched to the left half position.

If, for example, the linear solenoid valve SLC 2 is formed by a normal close type and when the all-off failure occurs at the forward fourth speed to the forward sixth speed, the output port SLC 2 b of the linear solenoid valve SLC 2 is closed and the controlled pressure P SLC2 becomes 0. On the other hand, the signal pressure P S1 is output from the solenoid valve S 11 formed by a normal open type, and input to the oil chamber 21 a of the first clutch apply relay valve 21 .

Since the signal pressure P S1 of the solenoid valve S 11 is also input to the oil chamber 22 a of the second clutch apply relay valve 22 , for example, if the second clutch apply relay valve 22 is switched to the right half position before the first clutch apply relay valve 21 is switched, the second preliminary hydraulic pressure P DC2 supplied to the oil passage j is supplied to the hydraulic servo 42 of the clutch C- 2 via the oil passages c 2 , c 3 and also to the oil chamber 21 d of the first clutch apply relay valve 21 via the oil passage c 5 . Accordingly, the first clutch apply relay valve 21 is maintained at the left half position (position on high speed side), thus achieving the forward fifth speed as described above, and posing no problem.

If, however, the second clutch apply relay valve 22 is switched later than the switching of the first clutch apply relay valve 21 , the controlled pressure P SLC2 of the oil chamber 21 d of the first clutch apply relay valve 21 becomes 0, and the signal pressure P S1 of the solenoid valve S 11 is input to the oil chamber 21 a . As a result, the first clutch apply relay valve 21 is switched to the right half position (position on low speed side), thus forming the forward third speed as described above, resulting in down-shifting.

To address this, in this hydraulic control device 1 1 , the linear solenoid valve SLC 2 is formed by the normal open type. Accordingly, even if the all-off failure occurs in the forward fourth speed to the forward sixth speed, the output port SLC 2 b of the linear solenoid valve SLC 2 opens, and the controlled pressure P SLC2 is output approximately equivalent to the forward range pressure P D , that is, the controlled pressure P SLC2 input to the oil chamber 21 d of the first clutch apply relay valve 21 does not decrease. Even when the signal pressure P S1 of the solenoid valve S 11 is input to the oil chamber 21 a , the controlled pressure P SLC2 of the oil chamber 21 d and the biasing force of the spring 21 s exceed it, and the first clutch apply relay valve 21 can be maintained at the left half position (position on high speed side), making it possible to prevent the malfunction of being switched to the right half position (position on low speed side).

The first clutch apply relay valve 21 is so structured that the forward range pressure P D (first preliminary hydraulic pressure P DC1 ) that has passed through the valve when at the right half position (position on low speed side) is input to the oil chamber 21 c and it is locked to the right half position, and even if the controlled pressure P SLC1 of the linear solenoid valve SLC 1 decreases due to a pressure regulating operation, etc., it can be maintained at the right half position. For this reason, in the case where the linear solenoid valve SLC 2 is formed by the normal close type, if the controlled pressure P SLC2 decreases and the spool 21 p of the first clutch apply relay valve 21 moves even slightly toward the right half position when the all-off failure occurs in the forward fourth speed to the forward sixth speed, the locking action of the forward range pressure P D of the oil chamber 21 c occurs, and the malfunction of being switched to the right half position tends to occur.

However, in this hydraulic control device 1 1 , because the linear solenoid valve SLC 2 is formed by the normal open type as described above, the controlled pressure P SLC2 supplied to the oil chamber 21 d is prevented from decreasing. Thus, the first clutch apply relay valve 21 can be securely maintained at the left half position (position on high speed side).

Second Embodiment

A second embodiment in which the first embodiment is partially changed will now be described with reference to FIG. 5 . Note that, in the second embodiment, only changed portions from the first embodiment are described and the same portions are attached with the same numerals and the description is omitted. For a hydraulic control device 1 2 shown in FIG. 5 , in comparison with the hydraulic control device 1 1 shown in FIG. 4 , the illustration of the linear solenoid valve SLB 1 , the hydraulic servos 44 , 45 of the brakes B- 1 , B- 2 , the solenoid valve S 12 , the C- 2 relay valve 23 , and the B- 2 relay valve 24 , etc. is omitted, although the hydraulic control device 1 2 includes them.

For the hydraulic control device 1 2 according to the second embodiment, the structures of a first clutch apply relay valve (preliminary shift speed switching valve) 121 and a second clutch apply relay valve (hydraulic pressure supply switching valve) 122 are changed in comparison with the hydraulic control device 1 1 according to the first embodiment. Especially, in the hydraulic control device 1 1 according to the first embodiment, the first clutch apply relay valve 21 is switched to the right half position (position on low speed side) based on the engaging pressure P C1 (controlled pressure P SLC1 ) of the clutch C- 1 and the signal pressure P S1 and switched to the left half position (position on high speed side) based on the engaging pressure P C2 (controlled pressure P SLC2 ) of the clutch C- 2 and the biasing force of the spring 21 s . However, the hydraulic control device 1 2 according to the second embodiment is so structured that the first clutch apply relay valve 121 is switched to the right half position (position on low speed side) based on the biasing force of a spring 121 s , and switched to the left half position (position on high speed side) based on the engaging pressure P C2 (controlled pressure P SLC2 ) of the clutch C- 2 .

Detailed Structure of Hydraulic Control Device

In detail, the first clutch apply relay valve 121 in the second embodiment has a spool (first spool) 121 p having land portions each formed to be small in diameter on the upper side in the figure and large on the lower side, and the spring (first biasing device) 121 s to bias the spool 121 p to the lower part in the figure. The first clutch apply relay valve 121 also has an oil chamber 121 a at the upper part in the figure of the spool 121 p , and an oil chamber (first oil chamber) 121 e at the lower part in the figure of the spool 121 p , and furthermore, it has an output port 121 b , an input port 121 c , an output port 121 d and a drain port EX.

The first clutch apply relay valve 121 is so structured that, when the spool 121 p is shifted to the right half position (position on low speed side), the input port 121 c and the output port 121 b are communicated, the input port 121 c and the output port 121 d are disconnected, and the output port 121 d and the drain port EX are communicated, and when it is shifted to the left half position (position on high speed side), the input port 121 c and the output port 121 d are communicated, the input port 121 c and the output port 121 b are disconnected, and the output port 121 b and the drain port EX are communicated.

To the input port 121 c , a forward range pressure P D is input via the oil passage a 2 . The output port 121 b that is communicated with the input port 121 c when the spool 121 p is at the right half position is connected to an input port 122 d of the second clutch apply relay valve 122 via the oil passage k 1 , and connected to the oil chamber 121 a via the oil passage k 2 . The output port 121 d that is communicated with the input port 121 c when the spool 121 p is at the left half position is connected to an input port 122 g of the second clutch apply relay valve 122 via the oil passage j. Then, the oil chamber 121 e is connected to the hydraulic servo 42 of the clutch C- 2 via the oil passage c 5 and the C- 2 relay valve 23 not illustrated (see FIG. 4 ). That is, during normal operation, the oil chamber 121 e is connected to the output port SLC 2 b of the linear solenoid valve SLC 2 via the second clutch apply relay valve 122 described later.

On the other hand, the second clutch apply relay valve 122 has a spool (second spool) 122 p and a spring (second biasing device) 122 s to bias the spool 122 p to the upper part in the figure. The second clutch apply relay valve 122 also has an oil chamber (second oil chamber) 122 a at the upper part in the figure of the spool 122 p , and an oil chamber 122 h at the lower part in the figure of the spool 122 p , and furthermore, it has an input port 122 b , an output port 122 c , the input port 122 d , an input port 122 e , an output port 122 f , and the input port 122 g.

The second clutch apply relay valve 122 is so structured that, when the spool 122 p is shifted to the left half position (normal position), the input port 122 b and the output port 122 c are communicated, the input port 122 e and the output port 122 f are communicated, and the input port 122 d and the input port 122 g are disconnected, and when it is shifted to the right half position (failure position), the input port 122 d and the output port 122 c are communicated, the input port 122 g and the output port 122 f are communicated, and the input port 122 b and the output port 122 c are disconnected.

The oil chamber 122 a of the second clutch apply relay valve 122 is connected to the output port S 1 b of the solenoid valve S 11 via the oil passage h 3 . The oil chamber 122 h is connected to the output port SLC 1 b of the linear solenoid valve SLC 1 via an oil passage b 6 (illustration partially omitted) connected to the oil passage b 1 . In the second embodiment, the oil passage h 4 (see FIG. 4 ) is connected directly to the output port S 1 b of the solenoid valve S 1 , and the output port S 1 b is connected to the input port 24 c (see FIG. 4 ) of the B- 2 relay valve 24 (illustration omitted).

The input port 122 b of the second clutch apply relay valve 122 is connected to the output port SLC 1 b of the linear solenoid valve SLC 1 via the oil passage b 1 . The output port 122 c that is communicated with the input port 122 b when the spool 122 p is at the left half position and communicated with the input port 122 d when the spool 122 p is at the right half position is connected to the hydraulic servo 41 of the clutch C- 1 via the oil passage b 2 . On the other hand, the input port 122 e is connected to the output port SLC 2 b of the linear solenoid valve SLC 2 via the oil passage c 1 . The output port 122 that is communicated with the input port 122 e when the spool 122 p is at the left half position and communicated with the input port 122 g when the spool 122 p is at the right half position is connected to the hydraulic servo 42 of the clutch C- 2 via the oil passage c 2 , the C- 2 relay valve 23 not illustrated, and the oil passage c 3 .

Operation of Hydraulic Control Device During Normal Operation

If, for example, the driver turns the ignition ON, the solenoid valve S 11 is switched ON by the electrical command from the control unit during normal operation. Since the signal pressure P S1 is not output, the second clutch apply relay valve 122 is set to the left half position based on the biasing force of the spring 122 s , and since the input port 122 b and the output port 122 c , and the input port 122 e and the output port 122 f are communicated respectively, the controlled pressure P SLC1 of the linear solenoid valve SLC 1 and the controlled pressure P SLC2 of the linear solenoid valve SLC 2 b are freely supplied to the hydraulic servo 41 of the clutch C- 1 and the hydraulic servo 42 of the clutch C- 2 , respectively.

If the shift lever is changed from the N range position to the D range position by the driver, and the forward first speed to the forward third speed is judged by the control unit, the forward range pressure P D is output to the oil passages a 1 to a 5 from the forward range pressure output port of the manual shift valve, and the forward range pressure P D is input from the oil passage a 2 to the input port 121 c of the first clutch apply relay valve 121 . Then, the first clutch apply relay valve 121 is shifted to the right half position by the biasing force of the spring 121 s because the controlled pressure P SLC2 is not output from the linear solenoid valve SLC 2 (not input to the oil chamber 121 e ) in the forward first speed to the forward third speed (see FIG. 2 ), and the forward range pressure P D is output as the first preliminary hydraulic pressure P DC1 from the output port 121 b to the oil passage k 1 . However, the second clutch apply relay valve 122 , which has been shifted to the left half position by the biasing force of the spring 122 s because the solenoid valve S 11 is set to ON and the signal pressure P S1 is not output, is disconnected at the input port 122 d . At that time, the first preliminary hydraulic pressure P DC1 (forward range pressure P D ) is input to the oil chamber 121 a via the oil passage k 2 and the spool 121 p is stably held at the left half position. The hydraulic pressure (second preliminary hydraulic pressure P DC2 ) in the oil passage j is drained because the output port 121 d and the drain port EX are communicated.

The hydraulic control of the clutch C- 1 by the linear solenoid valve SLC 1 , hydraulic control of the brake B- 2 by the linear solenoid valve SLC 2 , hydraulic control of the brake B- 1 by the linear solenoid valve SLB 1 and hydraulic control of the clutch C- 3 by the linear solenoid valve SLC 3 are performed as in the case of the first embodiment described above, thereby achieving the forward first speed to the forward third speed appropriately.

If the forward fourth speed to the forward sixth speed is judged by the control unit, engagement of the clutch C- 2 is judged, and pressure regulation control of the linear solenoid valve SLC 2 is performed, and the controlled pressure P SLC2 is output from the linear solenoid valve SLC 2 . Then, the controlled pressure P SLC2 is input to the oil chamber 121 e of the first clutch apply relay valve 121 via the oil passage c 1 , the second clutch apply relay valve 122 , the oil passage c 2 , the C- 2 relay valve 23 (see FIG. 4 ) and the oil passage c 5 . Thus, the spool 121 p of the first clutch apply relay valve 121 is switched to the left half position because the controlled pressure P SLC2 of the oil chamber 121 e having a pressure receiving area of a large diameter prevails against the first preliminary hydraulic pressure P DC1 (forward range pressure P D ) of the oil chamber 121 a having a pressure receiving area of a small diameter and the biasing force of the spring 121 s . For this reason, the forward range pressure P D is output as a second preliminary hydraulic pressure P DC2 to the oil passage j from the output port 121 d . However, since the second clutch apply relay valve 122 has been shifted to the left half position by the biasing force of the spring 122 s as described above, it is disconnected at the input port 122 g . The hydraulic pressure (first preliminary hydraulic pressure P DC1 ) in the oil passages k 1 , k 2 and the oil chamber 121 a is drained because the output port 121 b and the drain port EX are communicated.

The hydraulic control of the clutch C- 1 by the linear solenoid valve SLC 1 , hydraulic control of the clutch C- 3 by the linear solenoid valve SLC 3 , and hydraulic control of the brake B- 1 by the linear solenoid valve SLB 1 are performed as in the case of the first embodiment described above, thereby achieving the forward fourth speed to the forward sixth speed appropriately.

Operation at Solenoid-All-Off Failure

Then, the operation at the solenoid-all-off failure in this hydraulic control device 1 2 will be described. For example, if the all-off failure occurs due to down, short-circuit, wire breakage, etc. of the control unit, the linear solenoid valve SLC 1 , the linear solenoid valve SLB 1 and the solenoid valve S 12 do not output the hydraulic pressure because they are of the normal close type, and the linear solenoid valve SLC 2 , the linear solenoid valve SLC 3 , and the solenoid valve S 11 output the hydraulic pressure because they are of the normal open type.

During normal running at the forward first speed to the forward third speed, the first clutch apply relay valve 121 has the spool 121 p locked to the right half position by the first preliminary hydraulic pressure P DC1 input to the oil chamber 121 a as described above. For this reason, the first preliminary hydraulic pressure P DC1 output from the output port 121 b is input to the input port 122 d of the second clutch apply relay valve 122 via the oil passage k 1 , and is blocked by the second clutch apply relay valve 122 shifted to the left half position (normal position).

If all-off failure occurs from this state, the second clutch apply relay valve 122 is switched to the right half position (failure position) as the signal pressure P S1 output from the solenoid valve S 11 is input to the oil chamber 122 a via the oil passage h 3 , and the first preliminary hydraulic pressure P DC1 input to the input port 122 d is output from the output port 122 c and input to the hydraulic servo 41 via the oil passage b 2 , and the clutch C- 1 is engaged. The pressure P SLC2 output from the linear solenoid valve SLC 2 normally opened is blocked by the input port 122 e of the second clutch apply relay valve 122 switched to the right half position. On the other hand, in the linear solenoid valve SLC 3 normally opened, the line pressure P L input to the input port SLC 3 a is output as engaging pressure P C3 , approximately as it is, from the output port SLC 3 b , and input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. Thus, the clutch C- 1 and the clutch C- 3 are engaged, achieving the forward third speed (see FIG. 2 ). That is, when the all-off failure occurs during running at the forward first speed to the forward third speed, the running state at the forward third speed is secured.

During the normal running at the forward fourth speed to the forward sixth speed, as described above, the controlled pressure P SLC2 (engaging pressure P C2 ) of the clutch C- 2 is input to the oil chamber 121 e of the first clutch apply relay valve 121 via the oil passage c 1 , the second clutch apply relay valve 122 , the oil passage c 2 , the C- 2 relay valve 23 (see FIG. 4 ), and the oil passage c 5 , and the spool 121 p is locked to the left half position. Therefore, the second preliminary hydraulic pressure P DC2 output from the output port 121 d is input to the input port 122 g of the second clutch apply relay valve 122 via the oil passage j, and is blocked by the second clutch apply relay valve 122 shifted to the left half position.

If all-off failure occurs from this state, the second clutch apply relay valve 122 is switched to the right half position as the signal pressure P S1 output from the solenoid valve S 11 is input to the oil chamber 122 a via the oil passage h 3 , and the second preliminary hydraulic pressure P DC2 input to the input port 122 g is output from the output port 122 f , and input to the hydraulic servo 42 via the oil passage c 2 , the C- 2 relay valve 23 (see FIG. 4 ) and the oil passage c 3 , and the clutch C- 2 is engaged. The pressure P SLC2 (engaging pressure P C2 ) output from the linear solenoid valve SLC 2 normally opened is blocked by the input port 122 e of the second clutch apply relay valve 122 switched to the right half position. However, since the second preliminary hydraulic pressure P DC2 output to the oil passage c 2 is also output to the oil passage c 5 and input to the oil chamber 121 e of the first clutch apply relay valve 121 , the first clutch apply relay valve 121 is continuously locked to the left half position. With the linear solenoid valve SLC 3 normally opened, the line pressure P L input to the input port SLC 3 a is output as the engaging pressure P C3 , approximately as it is, from the output port SLC 3 b and input to the hydraulic servo 43 via the oil passage e 1 , and the clutch C- 3 is engaged. By this, the clutch C- 2 and the clutch C- 3 are engaged, achieving the forward fifth speed (see FIG. 2 ). That is, the running state at the forward fifth speed is secured when the all-off failure occurs during the running at the forward fourth speed to the forward sixth speed.

If all-off failure occurs during normal running at the forward fourth speed to the forward sixth speed and when the vehicle is stopped and the shift lever is moved to the N range position, the manual shift valve not illustrated stops the output of the forward range pressure P D and drains it. Especially the forward range pressure P D to the linear solenoid valve SLC 2 normally opened and to the input port 121 c of the first clutch apply relay valve 121 is drained. Then, the second preliminary hydraulic pressure P DC2 input to the oil chamber 121 e via the oil passages j, c 2 , c 5 is drained, the lock by the second preliminary hydraulic pressure P DC2 is unlocked, and the spool 121 p is switched to the right half position by the biasing force of the spring 121 s . Since the signal pressure P S1 continues to be output from the solenoid valve S 11 normally opened, the second clutch apply relay valve 122 is left at the right half position by the signal pressure P S1 continuously input to the oil chamber 122 a.

In the N range state at the all-off failure, since the line pressure P L serves as the original pressure, and the controlled pressure P SLC3 (engaging pressure P C3 ) approximately the same as the line pressure P L is output from the linear solenoid valve SLC 3 normally opened, the clutch C- 3 is in an engaged state. Even when the clutch C- 3 is engaged, the clutches C- 1 , C- 2 and the brakes B- 1 , B- 2 are in a released state, and even when decelerated rotation is input to the sun gear S 2 , the sun gear S 3 and the carrier CR 2 are idled. Therefore, an approximate neutral state is established between the input shaft 10 and the counter gear 11 (see FIG. 1 ).

If the shift lever is moved again to the D range position by the driver, the forward range pressure P D is output from the manual shift valve, and the forward range pressure P D is input to the input port 121 c of the first clutch apply relay valve 121 switched to the right half position, and output as the first preliminary hydraulic pressure P DC1 from the output port 121 b to the oil passage k 1 , and input to the hydraulic servo 41 of the clutch C- 1 via the input port 122 d and the output port 122 c of the second clutch apply relay valve 122 at the right half position, and the oil passage b 2 , and the clutch C- 1 is engaged. That is, the same state occurs as in the all-off failure during the running at the forward first speed to the forward third speed, and the forward third speed is secured. This makes it possible to restart the vehicle even after the vehicle is stopped once after the all-off failure, and secure the limp-home function.

As described above, in the hydraulic control device 1 2 according to the present invention, the clutches C- 1 , C- 2 and C- 3 are controlled such that they are freely engaged by the controlled pressures P SLC1 , P SLC2 and P SLC3 by means of the linear solenoid valves SLC 1 , SLC 2 , and SLC 3 , respectively, during normal running. At the all-off failure, the controlled pressure P SLC3 of the linear solenoid valve SLC 3 is supplied to the hydraulic servo 43 of the clutch C- 3 , and the output state of the first or second preliminary hydraulic pressure P DC1 , P DC2 is switched in accordance with the engaged state of the clutch C- 2 by means of the first clutch apply relay valve 121 , making it possible to supply the first or second preliminary hydraulic pressure P DC1 , P DC2 to the hydraulic servo 41 of the clutch C- 1 or to the hydraulic servo 42 of the clutch C- 2 by means of the second clutch apply relay valve 122 . This makes it possible to achieve the forward third speed or the forward fifth speed in accordance with the shift speed before the all-off failure occurs when it occurs during running, with a structure equipped with only two valves, i.e., the first clutch apply relay valve 121 and the second clutch apply relay valve 122 , thus realizing compactness and cost reduction.

With the hydraulic control device 1 2 according to the second embodiment, the spool 121 p of the first clutch apply relay valve 121 is shifted to the right half position (position on low speed side) by the biasing force of the spring 121 s at the forward first speed to the forward third speed (shift speed on low speed side) with the clutch C- 2 not engaged. At the forward fourth speed to the forward sixth speed (shift speed on high speed side) with the clutch C- 2 engaged, the spool 121 p is shifted to the left half position (position on high speed side) by the engaging pressure P C2 of the clutch C- 2 of the oil chamber 121 e against the biasing force of the spring 121 s . This makes it possible to supply the first preliminary hydraulic pressure P DC1 to the hydraulic servo 41 of the clutch C- 1 when the all-off failure occurs while at the right half position, and to supply the second preliminary hydraulic pressure P DC2 to the hydraulic servo 42 of the clutch C- 2 when the all-off failure occurs while at the left half position.

The first clutch apply relay valve 121 can switch to the right half position (position on low speed side) or to the left half position (position on high speed side) only by the force relationship between the engaging pressure P C2 of the clutch C- 2 input to the oil chamber 121 e and the biasing force of the spring 121 s . Therefore, the oil passage b 4 to introduce the engaging pressure P C1 of the clutch C- 1 and the oil passage h 2 to introduce the signal pressure P S1 are not required (see FIG. 4 ), making it possible to adopt a simple oil passage structure, in comparison with, for example, a device (e.g. the hydraulic control device 1 1 in the first embodiment) to input the engaging pressure P C1 of the clutch C- 1 and the engaging pressure P C2 of the clutch C- 2 to the spool 121 p from mutually opposing directions, thus switching to the right half position or left half position by the force relationship between them. In addition, the oil chamber 21 b to which the engaging pressure P C1 of the clutch C- 1 is input, the spool 21 q , and the spring 21 t are not required (see FIG. 4 ), making it possible to shorten the length of the first clutch apply relay valve 121 , thus realizing further compactness and cost reduction.

When restarting the vehicle in the state of the all-off failure occurring, the first clutch apply relay valve 121 is switched to the right half position (position on low speed side) based on the biasing force of the spring 121 s and the second clutch apply relay valve 122 is switched to the right half position (failure position). As a result, the first preliminary hydraulic pressure P DC1 is supplied to the hydraulic servo 41 of the clutch C- 1 , and therefore, the forward third speed is achieved and the vehicle can be restarted.

To be specific, since the first clutch apply relay valve 121 inputs the forward range pressure P C as the original pressure of the first and second preliminary hydraulic pressures P DC1 , P DC2 , when restarting the vehicle in the state of all-off failure occurring, if the manual shift valve is switched to the neutral (N) range and the forward range pressure P D is discharged, and then it is switched again to the forward (D) range for example, the first preliminary hydraulic pressure P DC1 is supplied to the hydraulic servo 41 of the clutch C- 1 , thereby achieving the forward third speed and restarting the vehicle. This makes it possible to eliminate the necessity of separate operation such as stopping the engine once when restarting the vehicle in the state of all-off failure occurring.

Since the solenoid valve S 11 of the normal open type to be energized during normal running or to output the signal pressure P S1 during non-energizing is provided, the second clutch apply relay valve 122 can be switched to the left half position (normal position) by the biasing force of the spring 122 s or to the right half position (failure position) by the signal pressure P S1 of the solenoid valve S 11 input to the oil chamber 122 a.

In the hydraulic control device 1 2 in the second embodiment as well, the controlled pressure P SLC2 of the linear solenoid valve SLC 2 is supplied to the oil chamber 121 e of the first clutch apply relay valve 121 , and the spool 121 p is thereby switched to the left half-position at the forward fourth speed to the forward sixth speed during normal operation. If the linear solenoid valve SLC 2 is formed by the normal close type, when the all-off failure occurs at the forward fourth speed to the forward sixth speed, the signal pressure PSI is output from the solenoid valve S 11 formed by the normal open type. As a result, before the second clutch apply relay valve 122 is switched to the right-half position, the output port SLC 2 b of the linear solenoid valve SLC 2 is closed, and the controlled pressure P SLC2 may be reduced. That is, if the controlled pressure P SLC2 of the oil chamber 121 e is reduced before the second preliminary hydraulic pressure P DC2 is supplied to the oil chamber 121 e , the first clutch apply relay valve 121 is switched to the right half position (position on low speed side) by the biasing force of the spring 121 s , and the forward third speed is formed as described above, resulting in down-shifting.

That is, if the linear solenoid valve SLC 2 is formed by the normal open type in the hydraulic control device 1 2 of the second embodiment as well and when all-off failure occurs at the forward fourth speed to the forward sixth speed, the output port SLC 2 b of the linear solenoid valve SLC 2 opens and the controlled pressure P SLC2 approximately equivalent to the forward range pressure P D is output. Therefore, the controlled pressure P SLC2 input to the oil chamber 121 e of the first clutch apply relay valve 121 does not decrease, and the controlled pressure P SLC2 of the oil chamber 121 e does not become lower than the biasing force of the spring 121 s , thus making it possible to maintain the first clutch apply relay valve 121 at the left half position (position on high speed side) and prevent such malfunction that it is switched to the right half position (position on low speed side).

In the first and second embodiments described above, the hydraulic control devices 1 1 , 1 2 for the automatic transmission are applied, as an example, to the automatic transmission 3 that achieves six forward speeds and one reverse speed. However, the application is not limited to this, and for example, the hydraulic control devices 1 1 , 1 2 can be applied to an automatic transmission that achieves eight forward speeds, and the present invention can be applied to any automatic transmission so long as it is a multi-speed automatic transmission.

A hydraulic control device for an automatic transmission according to the present invention can be used for an automatic transmission installed in a passenger vehicle, truck, bus, agricultural machinery, etc. While the hydraulic control device achieves low speed or high speed at the occurrence of all-off failure based on the shift speed before the occurrence of the all-off failure, it is suitable for use in an automatic transmission requiring compactness and cost reduction.

According to an exemplary aspect of the invention, it is possible to control the first to third friction engagement elements in an engageable manner by the first to third hydraulic pressures of the first to third solenoid valves during normal running, and at a failure resulting in non-energizing, the third hydraulic pressure of the third solenoid valve is supplied to the hydraulic servo of the third friction engagement element, and the output state of the first or second preliminary hydraulic pressures is switched by the preliminary shift speed switching valve based on the engaged state of the second friction engagement element, and the first or second preliminary hydraulic pressure can be supplied to the hydraulic servo of first or second friction engagement element by the hydraulic pressure supply switching valve. If a failure that results in non-energizing occurs, a low speed or a high speed can be achieved in accordance with the shift speed before the occurrence of the failure with just a structure equipped with two valves, i.e., the preliminary shift speed switching valve and the hydraulic pressure supply switching valve, making it possible to achieve compactness and cost reduction.

According to an exemplary aspect of the invention, the first spool of the preliminary shift speed switching valve is shifted to the low speed side position by the biasing force of the first biasing device at a low speed side shift speed with the second friction engagement element not engaged, while it is shifted to the high speed side position by the engaging hydraulic pressure of the second friction engagement element of the first oil chamber against the biasing force of the first biasing device at a high speed side shift speeds with the second friction engagement element engaged. This makes it possible to supply the first preliminary hydraulic pressure to the hydraulic servo of the first friction engagement element when a failure that results in non-energizing occurs at the low seed side shift speed, and to supply the second preliminary hydraulic pressure to the hydraulic servo of the second friction engagement element when a failure that results in non-energizing occurs at the high speed side shaft speed.

The preliminary shift speed switching valve can switch to the low speed side position and the high speed side position simply by the force relationship between the engaging hydraulic pressure of the second friction engagement element input to the first oil chamber and the biasing force of the first biasing device. Therefore, a simple oil passage structure can be made and the length of the preliminary shift speed switching valve can be shortened, in comparison with a device to input the engaging hydraulic pressure of the first friction engagement element and the engaging hydraulic pressure of the second friction engagement element to the spool in a mutually opposing way so as to switch to the low speed side position and the high-speed side position by means of the force relationship between them, further promoting the compactness and cost reduction.

According to an exemplary aspect of the invention, since the second solenoid valve is formed by the normal open type that outputs the second hydraulic pressure during non-energizing, the second hydraulic pressure does not decrease even when a failure that results in non-energizing occurs at a high speed side shift speeds. Further, since the second hydraulic pressure input to the first oil chamber of the preliminary shift speed switching valve does not become smaller than the biasing force of the first biasing device, the preliminary shift speed switching valve can be maintained at the high speed side position. Thus, malfunction of the preliminary shift speed-switching valve being switched to a low speed side position can be prevented.

According to an exemplary aspect of the invention, when restarting under a failure that results in non-energizing, the preliminary shift speed switching valve is switched to the low speed side position based on the biasing force of the first biasing device and the hydraulic pressure supply switching valve is switched to the failure position. Thus, the first preliminary hydraulic pressure is supplied to the hydraulic servo of the first friction engagement element. Therefore, the low speed is achieved, making it possible to restart the vehicle.

According to an exemplary aspect of the invention, since the preliminary shift speed switching valve is inputted the forward range pressure as the original pressure of first and second preliminary hydraulic pressures, when restarting under a failure that results in non-energizing, the range switching valve is switched to another range to discharge the forward range pressure, and then switched again to the forward range. As a result, the first preliminary hydraulic pressure is supplied to the hydraulic servo of the first friction engagement element, and a low speed is achieved, thus making it possible to restart the vehicle. This eliminates separate operations such as temporary stop of the engine when restarting under the failure that results in non-energizing.

According to an exemplary aspect of the invention, since the fourth solenoid valve formed by the normal open type that is energized during normal running and outputs the signal hydraulic pressure during non-energizing is provided, it is possible to switch the hydraulic pressure supply switching valve to the normal position by the biasing force of the second biasing device and to the failure position by the signal hydraulic pressure of the fourth solenoid valve input to the second oil chamber.