Power transmission apparatus for a vehicle

This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0091540, filed on Aug. 7, 2018, which is incorporated herein by reference in its entirety.

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.

An environment-friendly technology of a vehicle is a core technology for controlling an automotive industry in future, and car manufacturers have focused on the development of the environment-friendly vehicle for satisfying environmental and fuel efficiency regulations.

An electric vehicle (EV), 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 the vehicle technology in future.

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

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.

In comparison with an automatic transmission using planetary gears, the DCT has benefits, such as higher efficiency in power delivery, easier modification in revising or adding parts in order to achieve more shift-stages, etc., and thus it can more comfortably comply with fuel consumption regulation and efficiency in achieving more shift-stages.

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 having capable of enabling multiple shift-stages by a simplified arrangement, improving installability, and reducing an overall weight.

An exemplary form of the present disclosure provides a power transmission apparatus for a vehicle includes an engine with an engine output shaft and a motor/generator with a motor shaft. The power transmission apparatus may include first, second, and third input shafts, a power mediating shaft, first and second intermediate shafts, an idle shaft, first and second shifting sections, and an output shaft. The first input shaft may be selectively connected with the motor shaft. The second input shaft may be hollow, which is disposed coaxially with and exterior to the first input shaft without rotational interference, and selectively connected with the motor shaft. The third input shaft may be hollow, which is disposed coaxially with and exterior to the second input shaft without rotational interference, and selectively connected with the motor shaft. The power mediating shaft may be hollow, which is disposed coaxially with and exterior to the first input shaft without rotational interference. 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 idle shaft may be disposed in parallel with the first input 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 idle shaft, and the power mediating shaft. The first shifting section may selectively receive a first torque through the first and third input shafts and output a plurality of intermediate shift-stages shifted from the first torque. The second shifting section may include a planetary gear set having a sun gear fixedly connected with the power mediating shaft, form a third torque by combination of the first torque selectively transmitted from the first shifting section and a second torque received from the second input shaft, and output the third torque to the output shaft. The output shaft may be disposed on a same axis with the second intermediate shaft, selectively connected with the second intermediate shaft, and output the third torque received from the first and second shifting sections.

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 and a first driven gear, the first drive gear being fixedly connected with the third input shaft, the first driven gear being fixedly connected with the first intermediate shaft and externally gear-meshed with the first drive gear. The second gear set may include a second drive gear, an intermediate gear, and a second driven gear, the second drive gear being disposed coaxial with and exterior to the first intermediate shaft without rotational interference, the intermediate gear being fixedly connected with the power mediating shaft and externally gear-meshed with the second drive gear, the second driven gear being fixedly connected with the second intermediate shaft and externally gear-meshed with the intermediate gear. The third gear set may include a third drive gear and a third driven gear, the third drive gear being fixedly connected with the first input shaft, the third driven gear being disposed coaxially with and exterior to the second intermediate shaft without rotational interference and externally gear-meshed with the third drive gear. The fourth gear set may include a fourth drive gear and a fourth driven gear, the fourth drive gear being fixedly connected with the first input shaft, the fourth driven gear being disposed coaxially with and exterior to the second intermediate shaft without rotational interference and externally gear-meshed with the fourth drive gear. The fifth gear set may include the first drive gear and a fifth driven gear, the first drive gear being fixedly connected with the third input shaft, the fifth driven gear being fixedly connected with the idle shaft and externally gear-meshed with the first drive gear. The sixth gear set may include a sixth drive gear and the intermediate gear, the sixth drive gear being disposed coaxially with and exterior to the idle shaft without rotational interference, the intermediate gear being fixedly connected with the power mediating shaft and externally gear-meshed with the sixth drive gear.

The third driven gear and the fourth driven gear may be selectively interconnected through a first synchronizer. The second drive gear may be selectively connected with first intermediate shaft through a second synchronizer. The sixth drive gear may be selectively connected with the idle shaft through a third synchronizer.

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

The sun gear of the planetary gear set may be fixedly connected with the power mediating shaft. A planet carrier of the planetary gear set may be fixedly connected with the second input shaft. A ring gear of the planetary gear set may be externally gear-meshed with the output shaft through a seventh gear set.

The seventh gear set may include a seventh drive gear and a seventh driven gear. The seventh drive gear may be fixedly connected with the ring gear of the planetary gear set. The seventh driven gear may be fixedly connected with the output shaft and externally gear-meshed with the seventh drive gear.

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

According to one exemplary form of the present disclosure, the power transmission apparatus may further include four clutches each selectively connecting corresponding pair among the motor shaft, the engine output shaft, the first, second and third shafts, the power meditating shaft, the first and second intermediate shafts, the idle shaft and the output shaft, and a brake selectively connecting one of the shafts to the transmission housing.

The power transmission apparatus preferably includes an engine clutch disposed between the engine output and the motor shaft. The four clutches may include a first clutch disposed between the motor shaft and the first input shaft, a second clutch disposed between the motor shaft and the second input shaft, a third clutch disposed between the motor shaft and the third input shaft, and a fourth clutch disposed between the second intermediate shaft and the output shaft,

The brake may be disposed between the second intermediate shaft and the transmission housing.

The first and second shifting sections may be arranged such that the engine is disposed closer to the second shifting section than to the first shifting section.

A power transmission apparatus for a vehicle according to an exemplary form of the present disclosure realizes shift-stages of nine forward speeds and one reverse speed by employing a planetary gear set and three 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 exemplary form 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 areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purpose 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 be 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 an exemplary form of the present disclosure; and

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

The drawings described here 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.

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.

In the following description, various members are described as being connected, which may include members that are directly connected, fixedly connected, selectively connected or operably connected. In the drawings, various members are shown as being directly connected for movement together, and thus include members that are fixedly connected. Herein, the term “fixedly connected” or the like means at least two members that are connected to each other to always rotate together. When two or more members are described to be “selectively connected” by an engagement element, it means that the selectively connected member rotates separately when the engagement element is not engaged. 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 terms “operably connected”, “selectively connected” or the like.

FIG. 1 is a schematic view of a power transmission apparatus for a vehicle according to an exemplary form of the present disclosure.

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

The engine ENG as a primary power source may be realized as a various kind of typical engines such as a gasoline engine or a diesel engine that uses fossil fuel.

The motor/generator MG may act as a motor and as a generator, and includes a stator ST, which is fixed to the transmission housing H, and a rotor RT 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 torque from the engine ENG through a separate route, 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 power mediating shaft TMS are disposed on a same axis. The first and second intermediate shafts CS 1 and CS 2 , the idle shaft IDS, and the output shaft OS 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 in a rear of the engine ENG.

A motor shaft MDS fixedly connected with 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 selectively connected with the motor shaft MDS. 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 coaxially with and exterior to the first input shaft IS 1 without rotational interference, and selectively connected with the motor shaft MDS 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 coaxially with and exterior to the second input shaft IS 2 without rotational interference, and selectively connected with the motor shaft MDS thereby selectively transmitting torques of the engine ENG and the motor/generator MG to the first shifting section TM 1 .

The power mediating shaft TMS is formed as a hollow shaft and disposed coaxially with and exterior to the first input shaft IS 1 without rotational interference.

The second intermediate shaft CS 2 is selectively connected with the transmission housing H through a first brake B 1 , and may be rotationally fixed by the operation of the first brake B 1 .

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

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 first 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 arranged between the second input shaft IS 2 and the power mediating shaft TMS. The sun gear S is fixedly connected with the power mediating shaft TMS. The planet carrier PC is fixedly connected with the second input shaft IS 2 . The ring gear R is externally gear-meshed with the output shaft OS by a seventh gear set GL 7 .

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

The second gear set GL 2 includes a second drive gear IDG 2 , an intermediate gear ICDG, and a second driven gear IPG 2 . The second drive gear IDG 2 is disposed coaxially with and exterior to first intermediate shaft CS 1 without rotational interference. The intermediate gear ICDG is fixedly connected with the power mediating shaft TMS and externally gear-meshed with the second drive gear IDG 2 . The second driven gear IPG 2 is fixedly connected with the second intermediate shaft CS 2 , and externally gear-meshed with the intermediate gear ICDG.

The third gear set GL 3 includes a third drive gear IDG 3 and a third driven gear IPG 3 . The third drive gear IDG 3 is fixedly connected with the first input shaft IS 1 . The third driven gear IPG 3 is disposed coaxial with and exterior to the second intermediate shaft CS 2 without rotational interference, and externally gear-meshed with the third drive gear IDG 3 .

The fourth gear set GL 4 includes a fourth drive gear IDG 4 and a fourth driven gear IPG 4 . The fourth drive gear IDG 4 is fixedly connected with the first input shaft IS 1 . The fourth driven gear IPG 4 is disposed coaxially with and exterior to the second intermediate shaft CS 2 without rotational interference, and externally gear-meshed with the fourth drive gear IDG 4 .

The fifth gear set GL 5 includes the first drive gear IDG 1 and a fifth driven gear IPG 5 . The first drive gear IDG 1 is fixedly connected with the third input shaft IS 3 . The fifth driven gear IPG 5 is fixedly connected with the idle shaft IDS, and externally gear-meshed with the first drive gear IDG 1 .

The sixth gear set GL 6 includes a sixth drive gear IDG 6 and the intermediate gear ICDG. The sixth drive gear IDG 6 is disposed coaxially with and exterior to the idle shaft IDS without rotational interference. The intermediate gear ICDG is fixedly connected with the power mediating shaft TMS and externally gear-meshed with the sixth drive gear IDG 6 .

The seventh gear set GL 7 includes a seventh drive gear IDG 7 and a seventh driven gear IPG 7 . The seventh drive gear IDG 7 is fixedly connected with the ring gear of the planetary gear set PG. The seventh driven gear IPG 7 is fixedly connected with the output shaft OS, and externally gear-meshed with the seventh drive gear IDG 7 .

The third driven gear IPG 3 and the fourth driven gear IPG 4 are selectively connected with the second intermediate shaft CS 2 by a first synchronizer SN 1 .

The second drive gear IDG 2 is selectively connected with the first intermediate shaft CS 1 by a second synchronizer SN 2 .

The sixth drive gear IDG 6 is selectively connected with the idle shaft IDS by a third synchronizer SN 3 .

Gear ratios between drive and driven gears of the first, second, third, fourth, fifth, and sixth gear sets GL 1 , GL 2 , GL 3 , GL 4 , GL 5 , and GL 6 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 second speed FD 2 and the forward sixth speed FD 6 . The gear ratio of the third gear set GL 3 is used for realizing the forward first speed FD 1 and the forward seventh speed FD 7 . The gear ratio of the fourth gear set GL 4 is used for realizing the forward third speed FD 3 and the forward fifth speed FD 5 . 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 FD 9 and the reverse speed.

The output shaft OS is an output member, and by receiving torques input from the second intermediate shaft CS 2 and from the seventh gear set GL 7 , transmits the received torque to a differential DIFF through the output gear OG and the final reduction gear FDG.

In addition, four engagement elements of first, second, third, and fourth clutches CL 1 , CL 2 , CL 3 , and CL 4 are disposed between rotating members such as various shafts, and one engagement of a brake B 1 is disposed a rotating member and the transmission housing H.

The engine clutch ECL is disposed between the engine output shaft EOS (e.g., an engine crankshaft) and the motor shaft MDS, and selectively interconnects the engine output shaft EOS and the motor shaft MDS.

The first clutch CL 1 is disposed between the motor shaft MDS and the first input shaft IS 1 , so as to selectively interconnect the motor shaft MDS and the first input shaft IS 1 .

The second clutch CL 2 is disposed between the motor shaft MDS and the second input shaft IS 2 , so as to selectively interconnect the motor shaft MDS and the second input shaft IS 2 .

The third clutch CL 3 is disposed between the motor shaft MDS and the third input shaft IS 3 , so as to selectively interconnect the motor shaft MDS and the third input shaft IS 3 .

The fourth clutch CL 4 is disposed between the second intermediate shaft CS and the output shaft OS, so as to selectively interconnect the second intermediate shaft CS 2 and the output shaft OS.

The first brake B 1 is disposed between the second intermediate shaft CS 2 and the transmission housing H, so as to selectively activate the second intermediate shaft CS 2 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 configurations that are electrically controllable may be available.

The first, second, and third synchronizers SN 1 , SN 2 , and SN 3 may be formed as a known scheme, and first, second, and third sleeves SLE 1 , SLE 2 , and SLE 3 applied to the first, second, and third synchronizers SN 1 , SN 2 , and SN 3 may be operated by respective actuators (not shown) that may be controlled by a transmission control unit.

As shown in FIG. 1 , the second shifting section TM 2 is disposed at a rear of the engine ENG, and the first shifting section TM 1 is disposed at a rear of the second shifting section TM 2 .

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

[Engine and Parallel Mode Reverse Speed]

Hereinafter, the term “engine and parallel mode” indicates a mode that the engine ENG is running. The motor/generator MG may be activated or not. Thus, the term includes a pure engine mode in which only the engine ENG acts as a power source, and also includes a parallel mode in which both the engine ENG and the motor/generator MG act as power sources.

In the engine and parallel mode reverse speed REV, as shown in FIG. 2 , the idle shaft IDS and the sixth drive gear IDG 6 are interconnected by the sleeve SLE 3 of the third synchronizer SN 3 , 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 engine clutch ECL, the third clutch CL 3 , and the third synchronizer SN 3 , the torque of the engine ENG is transmitted to the second intermediate shaft CS 2 through the motor shaft MDS, the third input shaft IS 3 , the fifth gear set GL 5 , the idle shaft IDS, the third synchronizer SN 3 , and the sixth gear set GL 6 .

Then, by the operation of the fourth clutch CL 4 , the torque of the second intermediate shaft CS 2 is transmitted to the differential DIFF through the output shaft OS, thereby realizing the reverse speed REV.

[Engine and Parallel Mode Forward First Speed]

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

As a result, by the operation of the engine clutch ECL, the first clutch CL 1 , and the first synchronizer SN 1 , the torque of the engine ENG is transmitted to the second intermediate shaft OS 2 through the motor shaft MDS, the first input shaft IS 1 , the third gear set GL 3 , and the first synchronizer SN 1 .

Then, by the operation of the fourth clutch CL 4 , the torque of the second intermediate shaft CS 2 is transmitted to the differential DIFF through the output shaft OS, thereby realizing the forward first speed.

[Engine and Parallel Mode Forward Second Speed]

In the engine and parallel mode forward second speed FD 2 , as shown in FIG. 2 , the first intermediate shaft CS 2 and the second drive gear IDG 2 are interconnected by 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 engine clutch ECL, the third clutch CL 3 , and the second synchronizer SN 2 , the torque of the engine ENG is transmitted to the second intermediate shaft CS 2 through the motor shaft MDS, the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the second synchronizer SN 2 , and the second gear set GL 2 .

Then, by the operation of the fourth clutch CL 4 , the torque of the second intermediate shaft CS 2 is transmitted to the differential DIFF through the output shaft OS, thereby realizing the forward second speed.

[Engine and Parallel Mode Forward Third Speed]

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

As a result, by the operation of the engine clutch ECL, the first clutch CL 1 , and the first synchronizer SN 1 , the torque of the engine ENG is transmitted to the second intermediate shaft OS 2 through the motor shaft MDS, the first input shaft IS 1 , the fourth gear set GL 4 , and the first synchronizer SN 1 .

Then, by the operation of the fourth clutch CL 4 , the torque of the second intermediate shaft CS 2 is transmitted to the differential DIFF through the output shaft OS, thereby realizing the forward third speed.

[Engine and Parallel Mode Forward Fourth Speed]

In the engine and parallel mode forward fourth speed FD 4 , as shown in FIG. 2 , first, second, and third synchronizers SN 1 , SN 2 , and SN 3 are maintained at neutral state, and the engine clutch ECL and the second and fourth clutches CL 2 and CL 4 are operated.

As a result, by the operation of the engine clutch ECL and the second clutch CL 2 , the torque of the engine ENG is transmitted to the planet carrier PC of the planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 .

By the operation of the fourth clutch CL 4 , the seventh gear set GL 7 , the output shaft OS, the second intermediate shaft CS 2 , the second gear set GL 2 , and the power mediating shaft TMS are interconnected, and thereby the ring gear R connected to the seventh gear set GL 7 is connected with the sun gear S connected to the power mediating shaft TMS. The speed relation between the ring gear R and the sun gear S is formed by the gear ratios of the second and seventh gear sets GL 2 and GL 7 , while the planet carrier PC of the planetary gear set PG receives an input torque through the second input shaft IS 2 . Therefore, the sun gear S and the ring gear R of the planetary gear set PG rotates at respective speeds satisfying the speed relation while the planet carrier PC rotates at the speed of the motor shaft MDS.

By such a cooperative operation of rotation members of the planetary gear PG, the speed and torque of the output shaft OS connected to the seventh gear set GL 7 is determined and transmitted to the differential DIFF through the output shaft OS, thereby realizing the forward fourth speed.

[Engine and Parallel Mode Forward Fifth Speed]

In the engine and parallel mode forward fifth speed FD 5 , as shown in FIG. 2 , the second intermediate shaft CS and the fourth driven gear IPG 4 are interconnected by the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first and second clutch CL 1 and CL 2 are operated.

As a result, by the operation of the engine clutch ECL, the first clutch CL 1 , and the first synchronizer SN 1 , the torque of the engine ENG is partially input to the sun gear S of planetary gear set PG through the motor shaft MDS, the first input shaft IS 1 , the fourth gear set GL 4 , the first synchronizer SN 1 , the second intermediate shaft CS 2 , the second gear set GL 2 , and the power mediating shaft TMS.

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 planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 .

Then, the planetary gear set PG realizes shifting based on speed difference between the sun gear S and the planet carrier PC, and outputs the shifted torque to the differential DIFF through the output shaft OS, thereby realizing the forward fifth speed.

[Engine and Parallel Mode Forward Sixth Speed]

In the engine and parallel mode forward sixth speed FD 6 , as shown in FIG. 2 , the first intermediate shaft CS 1 and the second drive gear IDG 2 are interconnected by 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 engine clutch ECL and second clutch CL 2 , the torque of the engine ENG is partially input to the planet carrier PC of the planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 .

In addition, by the operation of the third clutch CL 3 and the second synchronizer SN 2 , the torque of the engine ENG is partially input to the sun gear S of planetary gear set PG through the motor shaft MDS, the third input shaft IS 3 , the first gear set GL 1 , the first intermediate shaft CS 1 , the second synchronizer SN 2 , the second gear set GL 2 , and the power mediating shaft TMS.

Then, the planetary gear set PG realizes shifting based on speed difference between the sun gear S and the planet carrier PC, and outputs the shifted torque to the differential DIFF through the output shaft OS, thereby realizing the forward sixth speed.

[Engine and Parallel Mode Forward Seventh Speed]

In the engine and parallel mode forward seventh speed FD 7 , as shown in FIG. 2 , the second intermediate shaft CS 2 and the third driven gear IPG 3 are interconnected by the sleeve SLE 1 of the first synchronizer SN 1 , and the engine clutch ECL and the first and second clutch CL 1 and CL 2 are operated.

As a result, by the operation of the engine clutch ECL, the first clutch CL 1 , and the first synchronizer SN 1 , the torque of the engine ENG is partially input to the sun gear S of planetary gear set PG through the motor shaft MDS, the first input shaft IS 1 , the third gear set GL 3 , the first synchronizer SN 1 , the second intermediate shaft OS 2 , the second gear set GL 2 , and the power mediating shaft TMS.

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 planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 .

Then, the planetary gear set PG realizes shifting based on speed difference between the sun gear S and the planet carrier PC, and outputs the shifted torque to the differential DIFF through the output shaft OS, thereby realizing the forward seventh speed.

[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, second, and third synchronizers SN 1 , SN 2 , and SN 3 are maintained at neutral state, 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 engine clutch ECL and the second clutch CL 2 , the torque of the engine ENG is transmitted to the planet carrier PC of the planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 , and the sun gear S of the planetary gear set PG acts as a fixed element by the operation of the first brake B 1 .

Then, since the planet carrier PC of the planetary gear set PG receives input torque while the sun gear S acts as a fixed element, the planetary gear set PG outputs an increased speed through the ring gear R, and the torque output through the ring gear R is transmitted to the differential DIFF through the seventh gear set GL 7 and the output shaft OS, thereby realizing the forward eighth speed

In such a forward eighth speed, the planetary gear set PG outputs a further increased speed than in the forward seventh speed.

[Engine and Parallel Mode Forward Ninth Speed]

In the engine and parallel mode forward ninth speed FD 9 , as shown in FIG. 2 , the idle shaft IDS and the sixth drive gear IDG 6 are interconnected by the sleeve SLE 3 of the third synchronizer SN 3 , 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 engine clutch ECL and second clutch CL 2 , the torque of the engine ENG is partially input to the planet carrier PC of the planetary gear set PG through the motor shaft MDS and the second input shaft IS 2 .

In addition, by the operation of the third clutch CL 3 , the torque of the engine ENG is partially input to the sun gear S of the planetary gear set PG through the motor shaft MDS, the third input shaft IS 3 , the fifth gear set GL 5 , the idle shaft IDS, the third synchronizer SN 3 , and the sixth gear set GL 6 .

Then the planetary gear set PG outputs a further increased speed through the ring gear R than in the forward eighth speed, and the torque output through the ring gear R is transmitted to the differential DIFF through the seventh gear set GL 7 and 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 according to an exemplary form of the present disclosure realizes shift-stages of nine forward speeds and one reverse speed by employing a planetary gear set and three 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 exemplary form 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.

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 : first brake

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

CS 1 , CS 2 : first and second intermediate shafts

ECL: engine clutch

EOS: engine output shaft (crankshaft)

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

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

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

IDS: idle shaft

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

MDS: motor shaft

OG: output gear

OS: output shaft

PG: planetary gear set

SN 1 , SN 2 , SN 3 : first, second, and third synchronizers

TMS: power mediating shaft

TM 1 , TM 2 : first and second shifting sections