Power transmission apparatus for a vehicle

This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0093572 filed on Aug. 10, 2018, the entire contents of which are incorporated herein by reference.

The present disclosure relates to a power transmission apparatus for a vehicle.

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

There has been recent emphasis on environmentally-friendly technologies for vehicles, and advanced car makers have begun to develop environmentally-friendly vehicles to achieve environmental and fuel efficiency regulations.

An electric vehicle (EV) or a hybrid electric vehicle (HEV) that utilizes electrical energy, or a double clutch transmission (DCT) improving efficiency and convenience of a transmission may be examples of such vehicle technology.

The double clutch transmission (DCT) includes two clutches devices and a gear train of a basically manual transmission, selectively transmits a torque input from an engine to two input shafts by using the two clutches devices, and outputs a torque shifted by the gear train.

Such a double clutch transmission (DCT) attempts to compactly realize a multi-stage transmission of more than five speeds. The DCT achieves an automated manual transmission (AMT) that removes the inconvenience of a manual shifting of a driver, by controlling two clutches and synchronizing devices by a controller.

We have discovered that, in comparison with an automatic transmission using planetary gears, such a DCT shows merits, such as higher efficiency in power delivery, easier modification in revising or adding parts in order to achieve more shift-stages, etc., and can more comfortably conform to fuel consumption regulation and efficiency in achieving more shift-stages.

The above information is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

Described herein is a power transmission apparatus for a vehicle which can achieve shift-stages in an electric vehicle mode and in a parallel hybrid mode by employing a planetary gear set and two synchronizers to a double clutch scheme, thereby improving fuel consumption and better applicability to a hybrid vehicle.

In one aspect, a power transmission apparatus is for a vehicle having an engine output shaft and a motor/generator having a motor shaft selectively connected to the engine output shaft. The power transmission apparatus may includes a first input shaft, a second input shaft, a third input shaft, a torque mediating shaft, a first intermediate shaft, a second intermediate shaft, first and second idle shafts, an output shaft, a first shifting section, and a second shifting section. The first input shaft may be directly connected with the motor/generator. The second input shaft may be formed as a hollow shaft, disposed coaxial with and external to the first input shaft without rotational interference, and selectively connected with the first input shaft. The third input shaft may be formed as a hollow shaft, disposed coaxial with and external to the second input shaft without rotational interference, and selectively connected with the first input shaft. The torque mediating shaft may be formed as a hollow shaft disposed coaxial with and external to the first input shaft without rotational interference, and selectively connected with the first input shaft. The first intermediate shaft may be disposed in parallel with the first input shaft. The second intermediate shaft may be disposed in parallel with the first input shaft, and selectively connected with a transmission housing. The first and second idle shafts may be disposed in parallel with the first input shaft. The output shaft may be disposed in parallel with the first input shaft and coaxially with the second intermediate shaft, and selectively connected with the second intermediate shaft. The first shifting section may include six gear sets disposed on the first and third input shafts, the first and second intermediate shafts, the first and second idle shafts, and the torque mediating shaft

The first shifting section may selectively receive torque through the first and third input shafts and output a plurality of intermediate shift-stages shifted from the received torque. The second shifting section may include a planetary gear set having a sun gear fixedly connected with the output shaft, form an output torque by combination a torque selectively transmitted from the first shifting section through the six gear sets and a torque received from the second input shaft, and output the output torque to the output shaft.

The first shifting section may include first, second, third, fourth, fifth, and sixth gear sets. The first gear set may include a first drive gear fixedly connected with the third input shaft, an idle gear fixedly connected with the first idle shaft and externally gear-meshed with the first drive gear, and a first driven gear fixedly connected with the first intermediate shaft and externally gear-meshed with the idle gear. The second gear set may include a second drive gear disposed coaxial with and external to the first intermediate shaft without rotational interference, and a second driven gear fixedly connected with the ring gear of the planetary gear set and externally gear-meshed with the second drive gear. The third gear set may include a third drive gear disposed coaxial with and external to the first intermediate shaft without rotational interference, and a third driven gear fixedly connected with the second intermediate shaft and externally gear-meshed with the third drive gear. The fourth gear set may include a fourth drive gear disposed coaxial with and external to the torque mediating shaft without rotational interference, and a second driven gear externally gear-meshed with the fourth drive gear. The fifth gear set may include a fifth drive gear disposed coaxial with and external to the torque mediating shaft without rotational interference, and a fifth driven gear fixedly connected with the second idle shaft and externally gear-meshed with the fifth drive gear. The sixth gear set may include a sixth drive gear fixedly connected with the second idle shaft, and a second driven gear externally gear-meshed with the sixth drive gear.

The second drive gear and the third drive gear may be selectively connected with the first intermediate shaft through the first synchronizer. The fourth drive gear and the fifth drive gear may be selectively connected with the torque mediating shaft through the second synchronizer.

Gear ratios of the first gear set and the second gear set may be used for realizing the forward first speed and the forward seventh speed. Gear ratios of the first gear set and the third gear set may be used for realizing the forward third speed and the forward fifth speed. A gear ratio of the fourth gear set may be used for realizing the forward second speed and the forward sixth speed. Gear ratios of the fifth gear set and the sixth gear set may be used for realizing the forward ninth speed and the reverse speed. A gear ratio of the seventh gear set may be used for realizing the forward fourth speed.

The ring gear of the planetary gear set may receive a torque from the first shifting section. The planet carrier of the planetary gear set may receive a torque from the second input shaft through the seventh gear set. The sun gear may be fixedly connected with the output shaft and selectively connected with the ring gear.

The seventh gear set may include a seventh drive gear fixedly connected with the second input shaft, and a seventh driven gear fixedly connected with the planet carrier of the planetary gear set and externally gear-meshed with the seventh drive gear.

The planetary gear set may be a single pinion planetary gear set.

The power transmission apparatus may further include five clutches each selectively connecting a corresponding pair among the shafts, and a brake selectively connecting a corresponding shaft to the transmission housing.

The five clutches may include an engine clutch arranged between the engine output shaft and the first input shaft, a first clutch arranged between the first input shaft and the third input shaft, a second clutch arranged between the first input shaft and the second input shaft, a third clutch arranged between the first input shaft and the torque mediating shaft, and a fourth clutch disposed between the ring gear and sun gear of the planetary gear set. The brake may be arranged between the second intermediate shaft and the transmission housing.

A power transmission apparatus for a vehicle realizes shift-stages of nine forward speeds and one reverse speed by employing a planetary gear set and two synchronizers to a multiple clutch transmission, thereby enabling multiple shift-stages by a simplified arrangement, improving installability, and reducing an overall weight.

In addition, an aspect of the present disclosure may receive torque from a motor/generator as well as an engine, such that a vehicle may be driving in an electric vehicle mode and parallel hybrid mode, thereby improving fuel consumption.

Further, effects that can be obtained or expected from aspects of the present disclosure are directly or suggestively described in the following detailed description. That is, various effects expected from aspects of the present disclosure are described in the following detailed description.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a schematic view of a power transmission apparatus for a vehicle; and

FIG. 2 is a shifting operational chart of a power transmission apparatus for a vehicle.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As those skilled in the art will realize, the contents may be modified in various different ways, all without departing from the spirit or scope of the present disclosure.

In the following description, dividing names of components into first, second and the like is to divide the names because the names of the components are similar to or the same as each other, and an order thereof is not particularly limited.

FIG. 1 is a schematic view of a power transmission apparatus for a vehicle.

Referring to FIG. 1 , a power transmission apparatus shifts torques of an engine ENG as a primary power source and a motor/generator MG as an auxiliary power source, and includes first, second, and third input shafts IS 1 , IS 2 , and IS 3 , torque mediating shaft TMS, first and second intermediate shafts CS 1 and CS 2 , first and second idle shafts IDS 1 and IDS 2 , first and second shifting sections TM 1 and TM 2 , and an output shaft OS.

The engine ENG is a primary power source and a variety of typical engines such as a gasoline engine or a diesel engine that uses fossil fuel may be used as the engine ENG.

The motor/generator MG as an auxiliary power source may act as a motor and also as a generator, and includes a stator ST and a rotor RT, where the stator ST is fixed to the transmission housing H and the rotor RT is rotatably supported within the stator ST.

Torques from the engine ENG and/or the motor/generator MG are supplied to the first shifting section TM 1 , and a plurality of intermediate shift-stages are formed at the first shifting section TM 1 by the supplied torques. Receiving a torque from the first shifting section TM 1 and selectively receiving a reverse torque from the engine ENG through the second input shaft IS 2 , the second shifting section TM 2 performs shifting operation and outputs a shifted torque through the output shaft OS.

The first, second, and third input shafts IS 1 , IS 2 , and IS 3 and the torque mediating shaft TMS are disposed on a same axis. The first and second intermediate shafts CS 1 and CS 2 , the output shaft OS, and the first and second idle shafts IDS 1 and IDS 2 are disposed in parallel with the first input shaft IS 1 . The second intermediate shaft CS 2 and the output shaft OS are disposed on a same axis and selectively interconnected with each other.

The motor/generator MG is disposed to be rear of the engine ENG. The rotor RT of the motor/generator MG is selectively connected with an output shaft EOS of the engine ENG interposing an engine clutch ECL.

The first input shaft IS 1 is fixedly connected with the rotor RT of the motor/generator MG. The first input shaft IS 1 delivers torques from the engine ENG and the motor/generator MG to the first shifting section TM 1 .

The second input shaft IS 2 is formed as a hollow shaft and disposed coaxial with and external to the first input shaft IS 1 without rotational interference, and selectively connected with the first input shaft IS 1 thereby selectively transmitting torques of the engine ENG and the motor/generator MG to the second shifting section TM 2 .

The third input shaft IS 3 is formed as a hollow shaft and disposed coaxial with and external to the second input shaft IS 2 without rotational interference, and selectively connected with the first input shaft IS 1 thereby transmitting the torques of the engine ENG and the motor/generator MG to the first shifting section TM 1 .

The torque mediating shaft TMS is formed as a hollow shaft and disposed coaxial with and external to the first input shaft IS 1 , and selectively connected with the first input shaft IS 1 .

The second intermediate shaft CS 2 is selectively connected with the transmission housing H through a first brake B 1 , and may be selectively fixed in a rotating direction.

The first shifting section TM 1 includes the first and third input shafts IS 1 and IS 3 , the first and second intermediate shafts CS 1 and CS 2 , the torque mediating shaft TMS, first, second, third, fourth, fifth, and sixth gear sets GL 1 , GL 2 , GL 3 , GL 4 , GL 5 , and GL 6 disposed on first and second idle shafts IDS 1 and IDS 2 .

The second shifting section TM 2 includes a planetary gear set PG. The planetary gear set PG is a single pinion planetary gear set, and includes a sun gear S, a planet carrier PC rotatably supporting a plurality of pinion gears P externally gear-meshed with the sun gear S, and a ring gear R internally gear-meshed with the plurality of pinion gears P.

The planetary gear set PG is disposed on the output shaft OS. The sun gear S is fixedly connected with the output shaft OS. The planet carrier PC is fixedly connected with the second input shaft IS 2 through the seventh gear set GL 7 . The ring gear R is fixedly connected with the second gear set GL 2 .

The planetary gear set PG may integrally rotate by selectively interconnecting two rotation elements among three rotation elements. According to one aspect of the present disclosure, the ring gear R is selectively connected with the sun gear S fixedly connected to the output shaft OS.

As a result, by the planetary gear set PG of the second shifting section TM 2 , torques input through the ring gear R and the planet carrier PC may be output as inputted, or such torques may be combined to form a shifted output torque when the input torques have different rotation speeds.

The first, second, third, fourth, fifth, sixth, and seventh input gear sets GL 1 , GL 2 , GL 3 , GL 4 , GL 5 , GL 6 , and GL 7 are arranged as follows.

The first gear set GL 1 includes a first drive gear IDG 1 fixedly connected with the third input shaft IS 3 , an idle gear IDG fixedly connected with the first idle shaft IDS 1 and externally gear-meshed with the first drive gear IDG 1 , and a first driven gear IPG 1 fixedly connected with the first intermediate shaft CS 1 and externally gear-meshed with the idle gear IDG.

The second gear set GL 2 includes a second drive gear IDG 2 rotatably disposed on an external circumference of the first intermediate shaft CS 1 without rotational interference, and a second driven gear IPG 2 fixedly connected with the ring gear R of the planetary gear set PG and externally gear-meshed with the second drive gear IDG 2 .

The third gear set GL 3 includes a third drive gear IDG 3 rotatably disposed on an external circumference of the first intermediate shaft CS 1 without rotational interference, and a third driven gear IPG 3 fixedly connected with the second intermediate shaft CS 2 and externally gear-meshed with the third drive gear IDG 3 .

The fourth gear set GL 4 includes a fourth drive gear IDG 4 rotatably disposed on an external circumference of the torque mediating shaft TMS without rotational interference, and a second driven gear IPG 2 fixedly connected with the ring gear R of the planetary gear set PG and externally gear-meshed with the fourth drive gear IDG 4 .

The fifth gear set GL 5 includes a fifth drive gear IDG 5 rotatably disposed on an external circumference of the torque mediating shaft TMS without rotational interference, and a fifth driven gear IPG 5 fixedly connected with the second idle shaft IDS 2 and externally gear-meshed with the fifth drive gear IDG 5 .

The sixth gear set GL 6 includes a sixth drive gear IDG 6 fixedly connected with the second idle shaft IDS 2 , and a second driven gear IPG 2 fixedly connected with the ring gear R of the planetary gear set PG and externally gear-meshed with the sixth drive gear IDG 6 .

The seventh gear set GL 7 includes a seventh drive gear IDG 7 fixedly connected with the second input shaft IS 2 , and a seventh driven gear IPG 7 fixedly connected with the planet carrier PC of the planetary gear set PG and externally gear-meshed with the seventh drive gear IDG 7 .

The second drive gear IDG 2 and the third drive gear IDG 3 selectively connected to the first intermediate shaft CS 1 by a first synchronizer SN 1 .

The fourth drive gear IDG 4 and the fifth drive gear IDG 5 selectively connected to the torque mediating shaft TMS by a second synchronizer SN 2 .

Gear ratios between drive and driven gears of the first, second, third, fourth, fifth, sixth, and seventh gear set GL 1 , GL 2 , GL 3 , GL 4 , GL 5 , GL 6 , and GL 7 may be appropriately set in consideration of transmission requirements. The gear ratios of the first gear set GL 1 and the second gear set GL 2 are used for realizing the forward first speed and the forward seventh speed. The gear ratios of the first gear set GL 1 and the third gear set GL 3 are used for realizing the forward third speed and the forward fifth speed. The gear ratio of the fourth gear set GL 2 is used for realizing the forward second speed and the forward sixth speed. The gear ratios of the fifth gear set GL 5 and the sixth gear set GL 6 are used for realizing the forward ninth speed and the reverse speed. The gear ratio of the seventh gear set GL 7 is used for realizing the forward fourth speed.

The output shaft OS is an output member, and by receiving torques input from the second shifting section TM 2 , transmits the received torque to a differential DIFF through the output gear OG and the final reduction gear FDG.

In addition, five engagement elements of an engine clutch ECL and first to fourth clutches CL 1 , CL 2 , CL 3 , and CL 4 are disposed between rotating members such as various shafts, and one engagement element of a brake B 1 is disposed between a rotating member and the transmission housing H.

The engine clutch ECL is arranged between the engine output shaft EOS (e.g., engine crankshaft) and the first input shaft IS 1 , and selectively interconnects the engine output shaft EOS and the first input shaft IS 1 .

The first clutch CL 1 is arranged between the first input shaft IS 1 and the third input shaft IS 3 , and selectively connects the first input shaft IS 1 and the third input shaft IS 3 .

The second clutch CL 2 is arranged between the first input shaft IS 1 and the second input shaft IS 2 , and selectively connects the first input shaft IS 1 and the second input shaft IS 2 .

The third clutch CL 3 is arranged between the first input shaft IS 1 and the torque mediating shaft TMS, and selectively connects the first input shaft IS 1 and the torque mediating shaft TMS.

The fourth clutch CL 4 is arranged between the ring gear R and the sun gear S, and selectively connects the ring gear R and the sun gear S.

Therefore, the planetary gear set PG integrally rotates by the operation of the fourth clutch CL 4 .

The first brake B 1 is arranged between the second intermediate shaft CS 2 and the transmission housing H, and therefore, the second intermediate shaft CS 2 selectively acts as a fixed element.

The engagement elements of the engine clutch ECL, the first to fourth clutches CL 1 to CL 4 , and the first brake B 1 may be realized as multi-plate hydraulic pressure friction devices that are frictionally engaged by hydraulic pressure, however, it should not be understood to be limited thereto, since various other configuration that are electrically controllable may be available.

The first and second synchronizers SN 1 and SN 2 may be formed as a known scheme, and the first and second sleeves SLE 1 and SLE 2 applied to the first and second synchronizers SN 1 and SN 2 may be operated by respective actuators (not shown) that may be controlled by a transmission control unit.

FIG. 2 is a shifting operational chart for a power transmission apparatus for a vehicle, and the power transmission apparatus for a vehicle which performs shifting operation as follows.

Engine and Parallel Mode Reverse Speed

In the engine and parallel mode reverse speed REV, as shown in FIG. 2 , the torque mediating shaft TMS and the fifth drive gear IDG 5 are synchronously connected by the operation of the sleeve SLE 2 of the second synchronizer SN 2 , and the engine clutch ECL and the third and fourth clutches CL 3 and CL 4 are operated.

As a result, by the operation of the third clutch CL 3 , the torque of the engine ENG is reversely input to the ring gear R of the second shifting section TM 2 through the first input shaft IS 1 , the torque mediating shaft TMS, the second synchronizer SN 2 , the fifth gear set GL 5 , the second idle shaft IDS 2 , and the sixth gear set GL 6 .

In addition, by the operation of the fourth clutch CL 4 , the planetary gear set PG of the second shifting section TM 2 integrally rotates, and therefore, the torque input to the ring gear R is output as inputted, to the differential DIFF through the output shaft OS, thereby realizing the reverse speed.

The Engine and Parallel Mode Forward First Speed

In the engine and parallel mode forward first speed FD 1 , as shown in FIG. 2 , the first intermediate shaft CS 1 and the second drive gear IDG 2 are synchronously interconnected by the operation of the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first, fourth clutch CL 1 and CL 4 are operated.

As a result, by the operation of the first clutch CL 1 , the torque of the engine ENG is input to the ring gear R of the second shifting section TM 2 through the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the first synchronizer SN 1 , and the second gear set GL 1 .

In addition, by the operation of the fourth clutch CL 4 , the planetary gear set PG of the second shifting section TM 2 integrally rotates, and therefore, the torque input to the ring gear R is output as inputted, to the differential DIFF through the output shaft OS, thereby realizing the forward first speed.

The Engine and Parallel Mode Forward Second Speed

In the engine and parallel mode forward second speed FD 2 , as shown in FIG. 2 , the torque mediating shaft TMS and the fourth drive gear IDG 4 are synchronously interconnected by the operation of the sleeve SLE 2 of the second synchronizer SN 2 , and the engine clutch ECL and the third and fourth clutches CL 3 and CL 4 are operated.

As a result, by the operation of the third clutch CL 3 , the torque of the engine ENG is input to the ring gear R of the second shifting section TM 2 through the first input shaft IS 1 , the torque mediating shaft TMS, the second synchronizer SN 2 , and the fourth gear set GL 4 .

In addition, by the operation of the fourth clutch CL 4 , the planetary gear set PG of the second shifting section TM 2 integrally rotates, and therefore, the torque input to the ring gear R is output as inputted, to the differential DIFF through the output shaft OS, thereby realizing the forward second speed.

The Engine and Parallel Mode Forward Third Speed

In the engine and parallel mode forward third speed FD 3 , as shown in FIG. 2 , the first intermediate shaft CS 1 and the third drive gear IDG 3 are synchronously interconnected by the operation of the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first, fourth clutch CL 1 and CL 4 are operated.

As a result, by the operation of the first clutch CL 1 , the torque of the engine ENG is input to the ring gear R of the second shifting section TM 2 through the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the first synchronizer SN 1 , the third gear set GL 3 , and the second intermediate shaft CS 2 .

In addition, by the operation of the fourth clutch CL 4 , the planetary gear set PG of the second shifting section TM 2 integrally rotates, and therefore, the torque input to the ring gear R is output as inputted, to the differential DIFF through the output shaft OS, thereby realizing the forward third speed.

The Engine and Parallel Mode Forward Fourth Speed

In the engine and parallel mode forward fourth speed FD 4 , as shown in FIG. 2 , both the first and second synchronizers SN 1 and SN 2 are maintained neutral, and the engine clutch ECL and the second, fourth clutch CL 2 and CL 4 are operated.

As a result, by the operation of the second clutch CL 2 , the torque of the second input shaft IS 2 is input to the planet carrier PC of the second shifting section TM 2 through the seventh gear set GL 7 .

In addition, by the operation of the fourth clutch CL 4 , the planetary gear set PG of the second shifting section TM 2 integrally rotates, and therefore, the torque input to the planet carrier PC is output as inputted, to the differential DIFF through the output shaft OS, thereby realizing the forward fourth speed.

That is, shifting in the forward fourth speed is made according to the gear ratio of the seventh gear set GL 7 .

The Engine and Parallel Mode Forward Fifth Speed

In the engine and parallel mode forward fifth speed FD 5 , as shown in FIG. 2 , the first intermediate shaft CS 1 and the third drive gear IDG 3 are synchronously interconnected by the operation of the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first and second clutches CL 1 and CL 2 are operated.

As a result, by the operation of the first clutch CL 1 , the torque of the engine ENG is partially input to the ring gear R of the second shifting section TM 2 through the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the first synchronizer SN 1 , the third gear set GL 3 , and the second intermediate shaft CS 2 .

In addition, by the operation of the second clutch CL 2 , the torque of the engine ENG is partially input to the planet carrier PC of the second shifting section TM 2 through the second input shaft IS 2 and the seventh gear set GL 7 .

Then, shifting is performed by cooperative operation of the ring gear R and the planet carrier PC in the second shifting section TM 2 according to a rotation speed difference, and a shifted torque is output to the differential DIFF through the output shaft OS, thereby realizing the forward fifth speed.

The Engine and Parallel Mode Forward Sixth Speed

In the engine and parallel mode forward sixth speed FD 6 , as shown in FIG. 2 , the torque mediating shaft TMS and the fourth drive gear IDG 4 are synchronously interconnected by the operation of the sleeve SLE 2 of the second synchronizer SN 2 , and the engine clutch ECL and the second and third clutches CL 2 and CL 3 are operated.

As a result, by the operation of the second clutch CL 2 , the torque of the engine ENG is partially input to the planet carrier PC of the second shifting section TM 2 through the second input shaft IS 2 and the seventh gear set GL 7 .

In addition, by the operation of the third clutch CL 3 , the torque of the engine ENG is partially input to the ring gear R of the second shifting section TM 2 through the first input shaft IS 1 , the torque mediating shaft TMS, the second synchronizer SN 2 , and the fourth gear set GL 4 .

Then, shifting is performed by cooperative operation of the ring gear R and the planet carrier PC in the second shifting section TM 2 according to a rotation speed difference, and a shifted torque is output to the differential DIFF through the output shaft OS, thereby realizing the forward sixth speed.

The Engine and Parallel Mode Forward Seventh Speed

In the engine and parallel mode forward seventh speed FD 7 , as shown in FIG. 2 , the first intermediate shaft CS 1 and the second drive gear IDG 2 are synchronously interconnected by the operation of the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first and second clutches CL 1 and CL 2 are operated.

As a result, by the operation of the first clutch CL 1 , the torque of the engine ENG is partially input to the ring gear R of the second shifting section TM 2 through the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the first synchronizer SN 1 , and the second gear set GL 2 .

In addition, by the operation of the second clutch CL 2 , the torque of the engine ENG is partially input to the planet carrier PC of the second shifting section TM 2 through the second input shaft IS 2 and the seventh gear set GL 7 .

Then, shifting is performed by cooperative operation of the ring gear R and the planet carrier PC in the second shifting section TM 2 according to a rotation speed difference, and a shifted torque is output to the differential DIFF through the output shaft OS, thereby realizing the forward seventh speed.

The Engine and Parallel Mode Forward Eighth Speed

In the engine and parallel mode forward eighth speed FD 8 , as shown in FIG. 2 , the first and second synchronizers SN 1 and SN 2 are maintained neutral, and the engine clutch ECL, the second clutch CL 2 and the first brake B 1 are operated.

As a result, by the operation of the second clutch CL 2 , the torque of the second input shaft IS 2 is input to the planet carrier PC of the second shifting section TM 2 through the seventh gear set GL 7 .

In addition, by the operation of the first brake B 1 , the ring gear R acts as a fixed element while the planet carrier PC receives an input torque, thereby forming an increased output speed, and a shifted torque is output to the differential DIFF through the output shaft OS, thereby realizing the forward eighth speed.

The Engine and Parallel Mode Forward Ninth Speed

In the engine and parallel mode forward ninth speed FD 9 , as shown in FIG. 2 , the torque mediating shaft TMS and the fifth drive gear IDG 5 are synchronously interconnected by the operation of the sleeve SLE 2 of the second synchronizer SN 2 , and the engine clutch ECL and the second and third clutches CL 2 and CL 3 are operated.

As a result, by the operation of the second clutch CL 2 , the torque of the second input shaft IS 2 is input to the planet carrier PC of the second shifting section TM 2 through the seventh gear set GL 7 .

In addition, by the operation of the third clutch CL 3 , the torque of the first input shaft IS 1 is reversely input to the ring gear R of the second shifting section TM 2 through the fifth gear set GL 5 , the second idle shaft IDS 2 , and the sixth gear set GL 6 .

Therefore, the planetary gear set PG outputs a further increased speed than in the forward eighth speed, and a shifted torque is output to the differential DIFF through the output shaft OS, thereby realizing the forward ninth speed.

In the above description of the “engine and parallel mode”, only the engine ENG is exampled as a power source. However, it may be obviously understood that such shifting operation may be maintained even if the motor/generator MG is activated to form a parallel mode and assist the engine ENG.

An electric vehicle mode EV mode differs from the engine and parallel mode, only in that the engine ENG is stopped while releasing the engine clutch ECL and only the motor/generator MG is used as sole power source. It may be understood that such a difference will not affect the above-described shifting operation, and thus, in such an electric vehicle mode EV mode the same shift-stages of one reverse speed REV and nine forward speeds of the forward first speed FD 1 to the forward ninth speed FD 9 may be obtained by the same operational chart.

A power transmission apparatus for a vehicle realizes shift-stages of nine forward speeds and one reverse speed by employing a planetary gear set and two synchronizers to a multiple clutch transmission, thereby enabling multiple shift-stages by a simplified arrangement, improving installability, and reducing an overall weight.

In addition, in one aspect of the present disclosure, a system or vehicle may receive torque from a motor/generator as well as an engine, such that a vehicle may be driving in an electric vehicle mode and parallel hybrid mode, thereby improving fuel consumption.

While the disclosure has been submitted with what is presently considered to be practical aspects, it is to be understood that the disclosure is not limited to the described aspects, but, on the contrary, will cover various modifications and equivalent arrangements included within the spirit and scope of the description.

B 1 : first brake

CL 1 , CL 2 , CL 3 , CL 4 : first, second, third, and fourth clutches

CS 1 , CS 2 : first and second intermediate shafts

ECL: engine clutch

EOS: engine output shaft (e.g., crankshaft)

GL 1 , GL 2 , GL 3 , GL 4 , GL 5 , GL 6 , GL 7 : first, second, third, fourth, fifth, sixth, and seventh gear set

IDG 1 , IDG 2 , IDG 3 , IDG 4 , IDG 5 , IDG 6 , IDG 7 : first, second, third, fourth, fifth, sixth, and seventh drive gears

IPG 1 , IPG 2 , IPG 3 , IPG 4 , IPG 5 , IPG 6 , IPG 7 : first, second, third, fourth, fifth, sixth, and seventh driven gears

IDS 1 , IDS 2 : first and second idle shafts

IDG: idle gear

IS 1 , IS 2 , IS 3 : first, second, and third input shafts

OG: output gear

OS: output shaft

PG: planetary gear set

SN 1 , SN 2 : first and second synchronizers

TMS: torque mediating shaft

TM 1 , TM 2 : first and second shifting sections