Power transmission apparatus for vehicle

This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0098123, filed on Aug. 22, 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.

Research on realizing more shift-stages of an automatic transmission are undertaken to achieve enhancement of fuel consumption and better drivability, and recently, increase of oil price is triggering a hard competition in enhancing fuel consumption of a vehicle.

In this sense, research on an engine has been undertaken to achieve weight reduction and to enhance fuel consumption by so-called downsizing research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shift stages.

In order to achieve more shift stages for an automatic transmission, the number of parts is typically increased, which may deteriorate installability, production cost, weight and/or power flow efficiency.

Therefore, in order to maximally enhance fuel consumption of a power transmission apparatus having more shift stages, it is important for better efficiency to be derived by a smaller number of parts.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the present 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.

The present disclosure provides a power transmission apparatus for a vehicle provided with one compound planetary gear set having four shafts having advantages of realizing shift-stages and providing better performance and fuel efficiency of a vehicle.

A power transmission apparatus for a vehicle according to various exemplary form of the present disclosure may include: an input shaft receiving an input torque of an engine; an output gear outputting an output torque; a compound planetary gear set including a first planetary gear set having first, second and third rotation elements, and a second planetary gear set having fourth, fifth and sixth rotation elements; a first shaft fixedly connected with the first rotation element and the fourth rotation element and selectively connected with the input shaft; a second shaft fixedly connected with the fifth rotation element, selectively connected with the input shaft and selectively connected with a transmission housing; a third shaft fixedly connected with the second rotation element, the sixth rotation element and the output gear; a fourth shaft fixedly connected with the third rotation element and selectively connected with the transmission housing; an intermediate shaft parallel to the input shaft; a first gear set transmitting the torque from the input shaft to the intermediate shaft; and a second gear set selectively transmitting the torque from the intermediate shaft to the fourth shaft.

Here, the term “fixedly connected” or the like means at least two members are connected to each other to always rotate together. Therefore, it is to be understood by a person of an ordinary skill in the art that the term “fixedly connected” or the like differs from the term “operably connected” or the like.

The power transmission apparatus may further include two clutches selectively connecting a corresponding pair among the input shaft, the first, second, third and fourth shafts, and the intermediate shaft, and two brakes selectively connecting a corresponding shaft selected among the input shaft, the first, second, third and fourth shafts, and the intermediate shaft to the housing.

The two clutches may include a first clutch arranged between the input shaft and the first shaft and a second clutch arranged between the input shaft and the second shaft, and the two brake may include a first brake arranged between the second shaft and the transmission housing and a second brake arranged between the fourth shaft and the transmission housing.

The first planetary gear set may be a single pinion planetary gear set, the first rotational element is a first sun gear, the second rotational element is a first planet carrier, and the third rotational element is a first ring gear and the second planetary gear set may be a single pinion planetary gear set, the fourth rotational element is a second sun gear, the fifth rotational element is a second planet carrier, and the sixth rotational element is a second ring gear.

The first gear set may include a first drive gear and a first driven gear, the first drive gear fixedly connected with the input shaft, and the first driven gear fixedly connected with the intermediate shaft and externally gear-meshed with the first drive gear, and the second gear set may include a second drive gear and a second driven gear, the second drive gear exteriorly disposed with the intermediate shaft without rotational interference and selectively connected with the intermediate shaft, and the second driven gear fixedly connected with the fourth shaft and externally gear-meshed with the second drive gear.

The power transmission apparatus may further include a third clutch selectively connecting the intermediate shaft and the second drive gear.

Gear ratios of the first gear set and the second gear set are configured to increase a rotation speed of the input shaft and to output the increased rotation speed to the fourth shaft.

The power transmission apparatus may further include a third gear set disposed for selectively transmitting a torque of the intermediate shaft to the first shaft.

The third gear set may include a third drive gear and a third driven gear, the third drive gear exteriorly disposed with the intermediate shaft without rotational interference and selectively connected with the intermediate shaft, and the third driven gear fixedly connected the first shaft and externally gear-meshed with the third drive gear.

The power transmission apparatus may further include a fourth clutch selectively connecting the intermediate shaft and the third drive gear.

A gear ratio of the third gear set may be the same as the gear ratio of the second gear set.

The power transmission apparatus may further include a fourth gear set disposed for selectively transmitting the torque of the intermediate shaft to the first shaft.

The fourth gear set may include a fourth drive gear and a fourth driven gear, the fourth drive gear exteriorly disposed with the intermediate shaft without rotational interference and selectively connected with the intermediate shaft, and the fourth driven gear fixedly connected the first shaft and externally gear-meshed with the fourth drive gear.

The power transmission apparatus may further include a fifth clutch selectively connecting the intermediate shaft and the fourth drive gear.

A gear ratio of the fourth gear set may be set for decreasing a rotation speed of the input shaft and outputting to the first shaft.

The present disclosure has been made in an effort to provide a power transmission apparatus for a vehicle provided with one compound planetary gear set having four shafts having advantages of realizing shift-stages and providing better performance and fuel efficiency of a vehicle.

A power transmission apparatus for a vehicle according to a first exemplary form enables shift-stages of forward five speeds and one reverse speed by applying one compound planetary gear set including four shafts.

Accordingly multi-stages may be enabled with simpler structure and reduced weight, thereby improving installability and fuel consumption.

A power transmission apparatus for a vehicle according to a second exemplary form further employs one gear set to the first exemplary form, and enables shift-stages of forward eight speeds and two reverse speeds.

A power transmission apparatus for a vehicle according to a third exemplary form further employs one gear set to the second exemplary form, and enables shift-stages of forward eleven speeds and three reverse speeds.

Further, effects that can be obtained or expected from exemplary forms of the present disclosure are directly or suggestively described in the following detailed description. That is, various effects expected from exemplary forms of the present disclosure will be 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 according to a first exemplary form of the present disclosure;

FIG. 2 is a shifting operational chart for a power transmission apparatus for a vehicle according to a first exemplary form of the present disclosure;

FIG. 3 is a schematic view of a power transmission apparatus for a vehicle according to a second exemplary form of the present disclosure;

FIG. 4 is a shifting operational chart for a power transmission apparatus for a vehicle according to a second exemplary form of the present disclosure;

FIG. 5 is a schematic view of a power transmission apparatus for a vehicle according to a third exemplary form of the present disclosure; and

FIG. 6 is a shifting operational chart for a power transmission apparatus for a vehicle according to a third exemplary form of the present disclosure.

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.

The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary forms of the present disclosure are shown.

As those skilled in the art would realize, the described forms may be modified in various different ways, all without departing from the spirit or scope of the present disclosure. The drawings and description are to be regarded as illustrative in nature and not restrictive, and like reference numerals designate like elements throughout the specification.

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 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 according to a first exemplary form of the present disclosure.

Referring to FIG. 1 , a power transmission apparatus includes: an input shaft IS, an output gear OG, a compound planetary gear set CPG including first and second planetary gear sets PG 1 and PG 2 forming four shafts TM 1 to TM 4 , engagement element including three clutches C 1 , C 2 , and C 3 and two brakes B 1 and B 2 , an intermediate shaft CS and first and second gear sets GL 1 and GL 2 .

The input shaft IS is an input member and the torque from a crankshaft of an engine, after being torque-converted through a torque converter, is input into the input shaft IS.

The output shaft OS is an output member and transmits driving torque received from the compound planetary gear set CPG to a driving wheel through a differential apparatus.

The first planetary gear set PG 1 is a single pinion planetary gear set and includes a first sun gear S 1 , a first planet carrier PC 1 rotatably supporting a first pinion P 1 that is externally meshed with the first sun gear S 1 , and a first ring gear R 1 that is internally meshed with the first pinion P 1 respectively as first, second, and third rotation elements N 1 , N 2 , and N 3 .

The second planetary gear set PG 2 is a single pinion planetary gear set and includes a second sun gear S 2 , a second planet carrier PC 2 rotatably supporting a second pinion P 2 that is externally meshed with the second sun gear S 2 , and a second ring gear R 2 that is internally meshed with the second pinion P 2 respectively as fourth, fifth, and sixth rotation elements N 4 , N 5 , and N 6 .

The first rotation element N 1 is fixedly connected with the fourth rotation element N 4 and the second rotation element N 2 is fixedly connected with the sixth rotation element N 6 and the compound planetary gear set includes four shafts TM 1 to TM 4 .

The four shaft TM 1 to TM 4 will be described in further detail.

The first shaft TM 1 is fixedly connected with the first rotation element N 1 (first sun gear S 1 ) and the fourth rotation element N 4 (second sun gear S 2 ) and selectively connected with the input shaft IS acting as an input element.

The second shaft TM 2 is fixedly connected with the fifth rotation element N 5 (second planet carrier PC 2 ), selectively connected with the input shaft IS acting as an input element and selectively connected with a transmission housing H acting as a fixing element.

The third shaft TM 3 is fixedly connected with the second rotation element N 2 (first planet carrier PC 1 ) and the sixth rotation element N 6 (second ring gear R 2 ) and fixedly connected with the output gear OG acting as an output element.

The fourth shaft TM 4 is fixedly connected with the third rotation element N 3 (first ring gear R 1 ) and selectively connected with a transmission housing H acting as a fixing element.

In addition, the fourth shaft TM 4 is selectively connected with the input shaft IS.

The intermediate shaft CS is disposed in parallel with the input shaft IS. And intermediate shaft CS receives the torque of the input shaft IS through the first gear set GL 1 and selectively transmits to the fourth shaft TM 4 through the second gear set GL 2 .

The first gear set GL 1 includes a first drive gear IPG 1 and a first driven gear ISG 1 , the first drive gear IPG 1 is fixedly connected with the input shaft IS, and the first driven gear ISG 1 is fixedly connected with the intermediate shaft CS and externally gear-meshed with the first drive gear IPG 1 .

The second gear set GL 2 includes a second drive gear IPG 2 and a second driven gear ISG 2 , the second drive gear IPG 2 is exteriorly disposed with the intermediate shaft CS without rotational interference and selectively connected with the intermediate shaft CS, and the second driven gear ISG 2 is fixedly connected with the fourth shaft TM 4 and externally gear-meshed with the second drive gear IPG 2 .

Gear ratios of the first gear set GL 1 and the second gear set GL 2 are set for increasing a rotation speed of the input shaft IS transmitted through the first shaft TM 1 and the second shaft TM 2 and outputting the increased rotation speed to the fourth shaft TM 4 .

The power transmission apparatus further includes two clutches selectively connecting a corresponding pair of the shafts and two brakes selectively connecting a corresponding shaft to the housing H.

The engagement elements of the two clutches C 1 and C 2 and the two brakes B 1 and B 2 are arranged as follows.

The first clutch C 1 is arranged between the input shaft IS and the first shaft TM and selectively connects the input shaft IS and the first shaft TM.

The second clutch C 2 is arranged between the input shaft IS and the second shaft TM 2 and selectively connects the input shaft IS and the second shaft TM 2 .

The first brake B 1 is arranged between the second shaft TM 2 and the transmission housing H and selectively connects the second shaft TM 2 and the transmission housing H.

The second brake B 2 is arranged between the fourth shaft TM 4 and the transmission housing H and selectively connects the fourth shaft TM 4 and the transmission housing H.

The power transmission apparatus further includes a third clutch C 3 arranged between the intermediate shaft CS and the second drive gear IPG 2 selectively connecting the intermediate shaft CS and the second drive gear IPG 2 .

The engagement elements of the first, second and third clutches C 1 , C 2 and C 3 and the first and second brakes B 1 and B 2 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.

FIG. 2 is a shifting operational chart for a power transmission apparatus for a vehicle according to a first exemplary form of the present disclosure, and the power transmission apparatus for a vehicle according to a first exemplary form performs shifting operation as follows.

[The Forward First Speed]

In the forward first speed shift-stage FD 1 , the first clutch C 1 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted into the forward first speed shift-stage FD 1 , and the forward first speed shift-stage FD 1 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Second Speed]

In the forward second speed shift-stage FD 2 , the second clutch C 2 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 , the torque of the engine is input to the second shaft TM 2 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted into the forward second speed shift-stage FD 2 , and the forward second speed shift-stage FD 2 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Third Speed]

In the forward third speed shift-stage FD 3 , the first clutch C 1 and the second clutch C 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 and the second shaft TM 2 by the operations of the first and second clutches C 1 and C 2 , the torque of the engine is input to the first shaft TM 1 and the second shaft TM 2 .

Then, the compound planetary gear set CPG including the first and second planetary gear sets PG 1 and PG 2 entirely rotates and the torque received at the first shaft TM 1 and the second shaft TM 2 is outputted as inputted, thereby realizing the forward third speed shift-stage FD 3 and outputting through the output gear OG connected with the third shaft TM 3 .

[The Forward Fourth Speed]

In the forward fourth speed shift-stage FD 4 , the second clutch C 2 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the second shaft TM 2 , and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the second shaft TM 2 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the second shaft TM 2 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward fourth speed shift-stage FD 4 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Fifth Speed]

In the forward fifth speed shift-stage FD 5 , the first clutch C 1 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the first shaft TM 1 , and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the first shaft TM 1 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the first shaft TM 1 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward fifth speed shift-stage FD 5 is output through the output gear OG connected to the third shaft TM 3 .

[The Reverse Speed]

In the reverse speed REV, the first clutch C 1 and the first brake B 1 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , therefore, the torque of the input shaft IS is shifted, the reverse speed REV is output through the output gear OG connected to the third shaft TM 3 .

The power transmission apparatus according to the first exemplary form of the present disclosure provided with the compound planetary gear set CPG forming the four shafts TM 1 to TM 4 may realize the forward fifth speeds and one reverse speed shift-stages by rotating the first and second shafts TM 1 and TM 2 with the same rotation speed of the input shaft IS, by acting the third shaft TM 3 as an output member, and by transmitting increased rotation speed to the fourth shaft TM 4 .

And the power transmission apparatus for a vehicle according to a first exemplary form may be enabled with simpler structure and reduced weight, thereby improving installability and fuel consumption.

FIG. 3 is a schematic view of a power transmission apparatus for a vehicle according to a second exemplary form of the present disclosure.

Referring to FIG. 3 , in comparison with the first exemplary form, a second exemplary form further includes a third gear set GL 3 such that a vehicle applied with the power transmission apparatus may be enabled with forward eighth speeds and two reverse speeds by further transmitting the torque of the input shaft IS to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

The third gear set GL 3 includes a third drive gear IPG 3 and a third driven gear ISG 3 , the third drive gear IPG 3 is exteriorly disposed with the intermediate shaft CS without rotational interference and selectively connected with the intermediate shaft CS, and the third driven gear ISG 3 is fixedly connected the first shaft TM 12 and externally gear-meshed with the third drive gear IPG 3 .

The power transmission apparatus further includes a fourth clutch C 4 selectively connecting the intermediate shaft CS and the third drive gear IPG 3 and a gear ratio of the third gear set GL 3 is the same as the gear ratio of the second gear set GL 2 .

The fourth clutch C 4 may be realized as a multi-plate hydraulic pressure friction device that is 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.

FIG. 4 is a shifting operational chart for a power transmission apparatus for a vehicle according to a second exemplary form of the present disclosure, and the power transmission apparatus for a vehicle according to a second exemplary form performs shifting operation as follows.

[The Forward First Speed]

In the forward first speed shift-stage FD 1 , the first clutch C 1 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted into the forward first speed shift-stage FD 1 , and the forward first speed shift-stage FD 1 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Second Speed]

In the forward second speed shift-stage FD 2 , the fourth clutch C 4 and the second brake B 2 are operated.

In a state that the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS, and the third gear set GL 3 .

Then the first shaft TM 1 is transmitted a further increased rotation speed than in the forward first speed due to the gear ratio of the first and third gear sets GL 1 and GL 3 .

While the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , the torque of the input shaft IS is shifted, and the forward second speed shift-stage FD 2 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Third Speed]

In the forward third speed shift-stage FD 3 , the second clutch C 2 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 , the torque of the engine is input to the second shaft TM 2 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted, and the forward third speed shift-stage FD 3 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Fourth Speed]

In the forward fourth speed shift-stage FD 4 , the second clutch C 2 and the fourth clutch C 4 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 and the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the second shaft TM 2 , and simultaneously input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

While the second shaft TM 2 is transmitted the same rotation speed of the input shaft IS, the first shaft TM 1 is transmitted increased rotation speed due to the gear ratio of the first and third gear sets GL 1 and GL 3 .

According to a speed difference between the second shaft TM 2 and the first shaft TM 1 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward fourth speed shift-stage FD 4 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Fifth Speed]

In the forward fifth speed shift-stage FD 5 , the first clutch C 1 and the second clutch C 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 and the second shaft TM 2 by the operations of the first and second clutches C 1 and C 2 , the torque of the engine is input to the first shaft TM 1 and the second shaft TM 2 .

Then, the compound planetary gear set CPG including the first and second planetary gear sets PG 1 and PG 2 entirely rotates and the torque received at the first shaft TM 1 and the second shaft TM 2 is outputted as inputted, thereby realizing the forward fifth speed shift-stage FD 5 and outputting through the output gear OG connected with the third shaft TM 3 .

[The Forward Sixth Speed]

In the forward sixth speed shift-stage FD 6 , the second clutch C 2 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the second shaft TM 2 , and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the second shaft TM 2 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the second shaft TM 2 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward sixth speed shift-stage FD 6 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Seventh Speed]

In the forward seventh speed shift-stage FD 7 , the first clutch C 1 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the first shaft TM 1 and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the first shaft TM 1 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the first shaft TM 1 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward seventh speed shift-stage FD 7 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Eighth Speed]

In the forward eighth speed shift-stage FD 8 , the third clutch C 3 and the fourth clutch C 4 are operated.

In a state that the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 and the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 and simultaneously input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

In this case, the same increased rotation speed is transmitted to the first shaft TM 1 and the fourth shaft TM 4 simultaneously so that the compound planetary gear set CPG entirely rotates. And the compound planetary gear set CPG outputs the rotation speed as inputted and the forward eighth speed shift-stage FD 8 is output through the output gear OG connected to the third shaft TM 3 .

[The Reverse First Speed]

In the reverse first speed shift-stage REV 1 , the first clutch C 1 and the first brake B 1 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , therefore, the torque of the input shaft IS is shifted, the reverse first speed REV 1 is output through the output gear OG connected to the third shaft TM 3 .

[Reverse Second Speed]

In the reverse second speed shift-stage REV 2 , the fourth clutch C 4 and the first brake B 1 are operated.

In a state that the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , torque of the engine is input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

Then first shaft TM 1 receives a further increased speed than in the reverse first speed due to the gear ratio of the first and the third gear set GL 1 and GL 3 .

In addition, while the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , the torque of the input shaft IS is shifted, the reverse second speed REV 2 is output through the output gear OG connected to the third shaft TM 3 .

The second exemplary form further includes the third gear set GL 3 and may be enabled with forward eighth speeds and two reverse speeds.

Also, the power transmission apparatus for a vehicle according to the second exemplary form may be enabled with simpler structure and reduced weight, thereby improving installability and fuel consumption.

FIG. 5 is a schematic view of a power transmission apparatus for a vehicle according to a third exemplary form of the present disclosure.

Referring to FIG. 5 , in comparison with the second exemplary form, a third exemplary form further includes a fourth gear set GL 4 such that a vehicle applied with the power transmission apparatus may be enabled with forward eleventh speeds and three reverse speeds by further transmitting the torque of the input shaft IS to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the fourth gear set GL 4 .

The fourth gear set GL 4 includes a fourth drive gear IPG 4 and a fourth driven gear ISG 4 , the fourth drive gear IPG 4 is exteriorly disposed with the intermediate shaft CS without rotational interference and selectively connected with the intermediate shaft CS, and the fourth driven gear ISG 4 is fixedly connected the first shaft TM 1 and externally gear-meshed with the fourth drive gear IPG 4 .

The power transmission apparatus further includes a fifth clutch C 5 selectively connecting the intermediate shaft CS and the fourth drive gear IPG 4 . A gear ratio of the fourth gear set GL 4 is set for decreasing a rotation speed of the input shaft IS and outputting to the first shaft TM 1 .

The fifth clutch C 5 may be realized as a multi-plate hydraulic pressure friction device that is 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.

FIG. 4 is a shifting operational chart for a power transmission apparatus for a vehicle according to a third exemplary form of the present disclosure, and the power transmission apparatus for a vehicle according to a third exemplary form performs shifting operation as follows.

[The Forward First Speed]

In the forward first speed shift-stage FD 1 , the fifth clutch C 5 and the second brake B 2 are operated.

In a state that the intermediate shaft CS is connected with the fourth drive gear IPG 4 by the operation of the fifth clutch C 5 , the rotation speed of the input shaft IS is reduced and transmitted to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the fourth gear set GL 4 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted into the forward first speed shift-stage FD 1 , and the forward first speed shift-stage FD 1 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Second Speed]

In the forward second speed shift-stage FD 2 , the first clutch C 1 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted into the forward second speed shift-stage FD 2 , output through the output gear OG connected to the third shaft TM 3 .

[The Forward Third Speed]

In the forward third speed shift-stage FD 3 , the fourth clutch C 4 and the second brake B 2 are operated.

In a state that the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS, and the third gear set GL 3 .

Then the first shaft TM 1 is transmitted a further increased speed than in the forward second speed due to the gear ratio of the first and third gear sets GL 1 and GL 3 .

While the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , the torque of the input shaft IS is shifted, and the forward third speed shift-stage FD 3 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Fourth Speed]

In the forward fourth speed shift-stage FD 4 , the second clutch C 2 and the second brake B 2 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 , the torque of the engine is input to the second shaft TM 2 .

And the fourth shaft TM 4 acts as a fixed element by the operation of the second brake B 2 , therefore, the torque of the input shaft IS is shifted, and the forward fourth speed shift-stage FD 4 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Fifth Speed]

In the forward fifth speed shift-stage FD 5 , the second clutch C 2 and the fourth clutch C 4 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 and the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the second shaft TM 2 , and simultaneously input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

While the second shaft TM 2 is transmitted the same rotation speed of the input shaft IS, the first shaft TM 1 is transmitted increased rotation speed due to the gear ratio of the first and third gear sets GL 1 and GL 3 .

According to a speed difference between the second shaft TM 2 and the first shaft TM 1 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward fifth speed shift-stage FD 5 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Sixth Speed]

In the forward sixth speed shift-stage FD 6 , the first clutch C 1 and the second clutch C 2 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 and the second shaft TM 2 by the operations of the first and second clutches C 1 and C 2 , the torque of the engine is input to the first shaft TM 1 and the second shaft TM 2 .

Then, the compound planetary gear set CPG including the first and second planetary gear sets PG 1 and PG 2 entirely rotates and the torque received at the first shaft TM 1 and the second shaft TM 2 is outputted as inputted, thereby realizing the forward sixth speed shift-stage FD 6 and outputting through the output gear OG connected with the third shaft TM 3 .

[The Forward Seventh Speed]

In the forward seventh speed shift-stage FD 7 , the second clutch C 2 and the fifth clutch C 5 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operations of second clutch C 2 and the intermediate shaft CS is connected with the fourth drive gear IPG 4 by the operation of the fifth clutch C 5 , the rotation speed of the input shaft IS is input to the second shaft TM 2 and simultaneously to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the fourth gear set GL 4 .

While the same rotation speed of input shaft IS is transmitted to the second shaft TM 2 , the rotation speed of the input shaft IS is reduced and transmitted to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the fourth gear set GL 4 .

According to a speed difference between the second shaft TM 2 and the first shaft TM 1 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward seventh speed shift-stage FD 7 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Eighth Speed]

In the forward eighth speed shift-stage FD 8 , the second clutch C 2 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the second shaft TM 2 by the operation of the second clutch C 2 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the second shaft TM 2 , and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the second shaft TM 2 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the second shaft TM 2 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward eighth speed shift-stage FD 8 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Ninth Speed]

In the forward ninth speed shift-stage FD 9 , the third clutch C 3 and the fifth clutch C 5 are operated.

In a state that the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 and the intermediate shaft CS is connected with the fourth drive gear IPG 4 by the operation of the fifth clutch C 5 , the torque of the engine is input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS, and the second gear set GL 2 and simultaneously input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS, and the fourth gear set GL 4 .

While the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 , the rotation speed of the input shaft IS is reduced and transmitted to the first shaft TM 1 due to the gear ratio of the first and the fourth gear sets GL 1 and GL 4 .

According to a speed difference between the first shaft TM 1 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward ninth speed shift-stage FD 9 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Tenth Speed]

In the forward tenth speed shift-stage FD 10 , the first clutch C 1 and the third clutch C 3 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 and the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the first shaft TM 1 and simultaneously input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 .

While the first shaft TM 1 is transmitted the same rotation speed of the input shaft IS, the fourth shaft TM 4 is transmitted increased rotation speed due to the gear ratio of the first and second gear sets GL 1 and GL 2 .

According to a speed difference between the first shaft TM 1 and the fourth shaft TM 4 , the compound planetary gear set CPG shifts the torque of the input shaft IS, and the forward tenth speed shift-stage FD 10 is output through the output gear OG connected to the third shaft TM 3 .

[The Forward Eleventh Speed]

In the forward eleventh speed shift-stage FD 11 , the third clutch C 3 and the fourth clutch C 4 are operated.

In a state that the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 and the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , the torque of the engine is input to the fourth shaft TM 4 through the first gear set GL 1 , the intermediate shaft CS and the second gear set GL 2 and simultaneously input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

In this case, the same increased rotation speed is transmitted to the first shaft TM 1 and the fourth shaft TM 4 simultaneously so that the compound planetary gear set CPG entirely rotates. And the compound planetary gear set CPG outputs the rotation speed as inputted and the forward eleventh speed shift-stage FD 11 is output through the output gear OG connected to the third shaft TM 3 .

[Reverse First Speed]

In the reverse first speed shift-stage REV 1 , the fifth clutch C 5 and the first brake B 1 are operated.

In a state that the intermediate shaft CS is connected with the second drive gear IPG 2 by the operation of the third clutch C 3 , the torque of the engine is input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS, and the fourth gear set GL 4 .

While the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , the torque of the input shaft IS is shifted and the reverse first speed REV 1 is output through the output gear OG connected to the third shaft TM 3 .

[Reverse Second Speed]

In the reverse second speed shift-stage REV 2 , the first clutch C 1 and the first brake B 1 are operated.

In a state that the input shaft IS is connected with the first shaft TM 1 by the operation of the first clutch C 1 , the torque of the engine is input to the first shaft TM 1 .

And the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , therefore, the torque of the input shaft IS is shifted, the reverse second speed REV 2 is output through the output gear OG connected to the third shaft TM 3 .

[Reverse Third Speed]

In the reverse third speed shift-stage REV 3 , the fourth clutch C 4 and the first brake B 1 are operated.

In a state that the intermediate shaft CS is connected with the third drive gear IPG 3 by the operation of the fourth clutch C 4 , torque of the engine is input to the first shaft TM 1 through the first gear set GL 1 , the intermediate shaft CS and the third gear set GL 3 .

Then first shaft TM 1 receives a further increased speed than in the reverse second speed due to the gear ratio of the first and the third gear set GL 1 and GL 3 .

In addition, while the second shaft TM 2 acts as a fixed element by the operation of the first brake B 1 , the torque of the input shaft IS is shifted, the reverse third speed REV 3 is output through the output gear OG connected to the third shaft TM 3 .

The third exemplary form further includes the fourth gear set GL 4 and may be enabled with forward eleventh speeds and three reverse speeds.

Also, the power transmission apparatus for a vehicle according to the third exemplary form may be enabled with simpler structure and reduced weight, thereby improving installability and fuel consumption.

While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present disclosure.

B 1 , B 2 : first, second brake

C 1 ,C 2 ,C 3 ,C 4 ,C 5 : first, second, third, fourth, fifth clutch

IS: input shaft

OG: output gear

CPG: compound planetary gear set

GL 1 ,GL 2 ,GL 3 ,GL 4 : first, second, third, fourth gear sets

IPG 1 ,IPG 2 ,IPG 3 ,IPG 4 : first, second, third, fourth drive gears

ISP 1 ,ISG 2 ,ISG 3 ,ISG 4 : first, second, third, fourth driven gears

PG 1 ,PG 2 : first, second planetary gear sets

TM 1 ,TM 2 ,TM 3 ,TM 4 . . . first, second, third, fourth shafts