Vehicular multi-stage transmission

This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0077037, filed Jun. 19, 2017, which is incorporated herein by reference in its entirety.

The present disclosure relates to a vehicular multi-stage transmission, and more particularly, to a technique for improving the fuel efficiency of a vehicle by implementing as many transmission stages as possible with a simple configuration.

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

The recent rise in oil prices leads vehicle manufacturers to a more competition to improve fuel efficiency. In the case of engines, efforts are being made to reduce weight and to improve fuel efficiency through technologies such as downsizing.

Meanwhile, among the fuel efficiency improvement methods that can be pursued in a transmission mounted in a vehicle, there is a method for improving fuel efficiency by enabling an engine to operate at a more efficient operating point by multi-staging the transmission.

In addition, multi-staging of such a vehicular transmission may further improve the quietness of the vehicle by enabling the engine to operate in a relatively low RPM zone.

As the number of transmission stages of a transmission increases, the number of internal components constituting the transmission increases, which may deteriorate the mountability, costs, weight, and transmission efficiency of the transmission. Therefore, in order to increase a fuel efficiency through the multi-staging of the transmission, it is important to devise a transmission structure that can increase efficiency with reduced components and a relatively simple structure.

It should be understood the foregoing description of the background art is merely intended to enhance the understanding of the background of the present disclosure and should not be construed as an admission that it is a prior art already known to a person ordinarily skilled in the art.

The present disclosure provides a vehicular multi-stage transmission, which is capable of improving the fuel efficiency of a vehicle by implementing as many transmission stages as possible with a small number of components and a simple configuration.

In one form of the present disclosure, a vehicular multi-stage transmission includes: an input shaft INPUT and an output shaft OUTPUT; a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , which are configured to transmit torque between the input shaft INPUT and the output shaft OUTPUT, each of the first, second, third and fourth planetary gear devices including first, second and third rotary elements; and seven shifting elements connected to the rotary elements of the planetary gear devices.

The first rotary element of the first planetary gear device PG 1 is connected to the second rotary element of the fourth planetary gear device PG 4 while being fixedly connected to the input shaft INPUT, the second rotary element of the first planetary gear device PG 1 is selectively connected to a transmission case by a first shifting element of the seven shifting elements while being selectively connected to the input shaft INPUT, the secondary rotary element of the first planetary gear device PG 1 is selectively connected to the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth planetary gear device PG 4 , and the third rotary element of the first planetary gear device PG 1 is fixedly connected to the second rotary element of the second planetary gear device PG 2 . The first rotary element of the second planetary gear device PG 2 is selectively connected to the second rotary element of the third planetary gear device PG 3 while being selectively connected to the transmission case by a second shifting element of the seven shifting elements. The second rotary element of the third planetary gear device PG 3 is connected to the third rotary element of the fourth planetary gear device PG 4 while being fixedly connected to the output shaft OUTPUT, and the third rotary element of the third planetary gear device PG 3 is selectively connected to the transmission case by a third shifting element of the seven shifting elements.

The first planetary gear device PG 1 , the second planetary gear device PG 2 , the third planetary gear device PG 3 , and the fourth planetary gear device PG 4 may be sequentially arranged along the axial direction of the input shaft INPUT and the output shaft OUTPUT.

The first shifting element selectively connecting the second rotary element of the first planetary gear device PG 1 to the transmission case is a first brake B 1 among the shifting elements, the second shifting element selectively connecting the first rotary element of the second planetary gear device PG 2 to the transmission case is a second brake B 2 among the shifting elements, and the third shifting element selectively connecting the third rotary element of the third planetary gear device PG 3 to the transmission case is a third brake B 3 among the shifting elements. The remaining elements among the seven shifting elements may be provided to form a selective connection between the rotary elements of the four planetary gear devices.

The remaining shifting elements includes first, second, third and fourth clutches. The first clutch CL 1 among the shifting elements may form a selective connection between the second rotary element of the first planetary gear device PG 1 and the input shaft INPUT, the second clutch CL 2 among the shifting elements may form a selective connection between the second rotary element of the first planetary gear device PG 1 and the third rotary element of the second planetary gear device PG 2 , the third clutch CL 3 among the shifting elements may form a selective connection between the first rotary element of the second planetary gear device PG 2 and the second rotary element of the third planetary gear device PG 3 , the fourth clutch CL 4 among the shifting elements may form a selective connection between the second rotary element of the fourth planetary gear device PG 4 and the input shaft INPUT, and the second rotary element of the third planetary gear device PG 3 may be fixedly connected to the third rotary element of the fourth planetary gear device PG 4 .

The first clutch CL 1 among the shifting elements may form a selective connection between the second rotary element of the first planetary gear device PG 1 and the input shaft INPUT, the second clutch CL 2 among the shifting elements may form a selective connection structure between the second rotary element of the first planetary gear device PG 1 and the third rotary element of the second planetary gear device PG 2 , the third clutch CL 3 among the shifting elements may form a selective connection structure between the first rotary element of the second planetary gear device PG 2 and the second rotary element of the third planetary gear device PG 3 , the fourth clutch CL 4 among the shifting elements may form a selective connection structure between the third rotary element of the fourth planetary gear device PG 4 and the output shaft OUTPUT, and the first rotary element of the first planetary gear device PG 1 may be fixedly connected to the second rotary element of the fourth planetary gear device PG 4 .

A vehicular multi-stage transmission in one form of the present disclosure includes: a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , each of the first, second, third and fourth planetary gear devices including first, second and third rotary elements; and seven shifting elements configured to variably provide a frictional force.

The vehicular multi-stage transmission further includes: a first rotary shaft RS 1 as an input shaft INPUT fixedly connected to the first rotary element of the first planetary gear device PG 1 ; a second rotary shaft RS 2 fixedly connected to the second rotary element of the first planetary gear device PG 1 ; a third rotary shaft RS 3 fixedly connected to the third rotary element of the first planetary gear device PG 1 and the third rotary element of the second planetary gear device PG 2 ; a fourth rotary shaft RS 4 fixedly connected to the first rotary element of the second planetary gear device PG 2 ; a fifth rotary shaft RS 5 fixedly connected to the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth rotary gear device PG 4 ; a sixth rotary shaft RS 6 as an output shaft OUTPUT fixedly connected to the second rotary element of the third planetary gear device PG 3 and the third rotary element of the fourth planetary gear device PG 4 ; a seventh rotary shaft RS 7 fixedly connected to the third rotary element of the third planetary gear device PG 3 ; and an eighth rotary shaft RS 8 fixedly connected to the second rotary element of the fourth planetary gear device PG 4 .

The first clutch CL 1 among the seven shifting elements is disposed between the first rotary shaft RS 1 and the second rotary shaft RS 2 , and the second clutch CL 2 is disposed between the second rotary shaft RS 2 and the fifth rotary shaft RS 5 . The third clutch CL 3 is disposed between the fourth shaft RS 4 and the sixth rotary shaft RS 6 , and the fourth clutch CL 4 is disposed between the first rotary shaft RS 1 and the eighth rotary shaft RS 8 . The first brake B 1 is disposed between the second rotary shaft RS 2 and the transmission case, the second brake B 2 is disposed between the fourth rotary shaft RS 4 and the transmission case, and the third brake B 3 is disposed between the seventh rotary shaft RS 7 and the transmission case.

The first planetary gear device PG 1 , the second planetary gear device PG 2 , the third planetary gear device PG 3 , and the fourth planetary gear device PG 4 may be sequentially arranged along the axial direction of the input shaft INPUT and the output shaft OUTPUT.

In addition, the first clutch CL 1 is configured to selectively connect the first rotary element of the first planetary gear device PG 1 to the second rotary element of the first planetary gear device PG 1 , the second clutch CL 2 is configured to selectively connect the second rotary element of the first planetary gear device PG 1 to the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth planetary gear device PG 4 , the third clutch CL 3 is configured to selectively connect the first rotary element of the second planetary gear device PG 2 to the second rotary element of the third planetary gear device PG 3 , and the fourth clutch CL 4 is configured to selectively connect the first rotary element of the first planetary gear device PG 1 to the second rotary element of the fourth planetary gear device PG 4 .

In another form of the present disclosure, a vehicular multi-stage transmission includes: a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , each of which includes first, second and third rotary elements; and seven shifting elements configured to variably provide a frictional force.

The vehicular multi-stage transmission further includes: a first rotary shaft RS 1 as an input shaft INPUT fixedly connected to the first rotary element of the first planetary gear device PG 1 and the second rotary element of the fourth planetary gear device PG 4 ; a second rotary shaft RS 2 fixedly connected to the second rotary element of the first planetary gear device PG 1 ; a third rotary shaft RS 3 fixedly connected to the third rotary element of the first planetary gear device PG 1 and the second rotary element of the second planetary gear device PG 2 ; a fourth rotary shaft RS 4 fixedly connected to the first rotary element of the second planetary gear device PG 2 ; a fifth rotary shaft RS 5 fixedly connected to the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth rotary gear device PG 4 ; a sixth rotary shaft RS 6 as an output shaft OUTPUT fixedly connected to the second rotary element of the third planetary gear device PG 3 ; a seventh rotary shaft RS 7 fixedly connected to the third rotary element of the third planetary gear device PG 3 ; and an eighth rotary shaft RS 8 fixedly connected to the third rotary element of the fourth planetary gear device PG 4 .

Among the seven shifting elements, the first clutch CL 1 is arranged between the first rotary shaft RS 1 and the second rotary shaft RS 2 , the second clutch CL 2 is arranged between the second rotary shaft RS 2 and the fifth rotary shaft RS 5 . The third clutch CL 3 is arranged between the fourth shaft RS 4 and the sixth rotary shaft RS 6 , the fourth clutch CL 4 is arranged between the sixth rotary shaft RS 6 and the eighth rotary shaft RS 8 , the first brake B 1 is arranged between the second rotary shaft RS 2 and the transmission case, the second brake B 2 is arranged between the fourth rotary shaft RS 4 and the transmission case, and the third brake B 3 is arranged between the seventh rotary shaft RS 7 and the transmission case.

The first planetary gear device PG 1 , the second planetary gear device PG 2 , the third planetary gear device PG 3 , and the fourth planetary gear device PG 4 may be sequentially arranged along the axial direction of the input shaft INPUT and the output shaft OUTPUT.

In addition, the first clutch CL 1 is configured to selectively connect the first rotary element of the first planetary gear device PG 1 and the second rotary element of the first planetary gear device PG 1 , the second clutch CL 2 is configured to selectively connect the second rotary element of the first planetary gear device PG 1 , the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth planetary gear device PG 4 , and the third clutch CL 3 is configured to selectively connect the first rotary element of the second planetary gear device PG 2 and the second rotary element of the third planetary gear device PG 3 .

The fourth clutch CL 4 is configured to selectively connect the second rotary element of the third planetary gear device PG 3 and the third rotary element of the fourth planetary gear device PG 4 .

According to the vehicular multi-stage transmission configured to have the above-described structure, the rotary elements, which constitute the first, second, third and fourth planetary gear sets, are shifted while changing the rotational speed and direction by selective operation of the clutches and the brakes, so that the vehicle can be driven by implementing a gear ratio of 10 or more forward stages and 1 or more reverse stages through such a shifting action.

Therefore, by making the automatic transmission have multiple stages, it is possible to improve fuel efficiency, and by using the operating point in a low RPM zone of the engine, it is possible to decrease the running noise of the vehicle.

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 a view schematically illustrating a vehicular multi-stage transmission structure in one form of the present disclosure;

FIG. 2 is a view schematically illustrating a vehicular multi-stage transmission structure in another form of the present disclosure; and

FIGS. 3 and 4 are tables representing operations for respective transmission stages of a vehicular multi-stage transmission in one 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.

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.

Here, the term “selectively connected” or the like means at least two members (e.g. a plurality of shafts including the input shaft and the output shaft, or plurality of rotary elements) that are connectable and disconnectable to/from each other, e.g. through at least one intermediate member or a shifting element, and when connected rotate with the same rotational speed, or are connectable to the transmission housing through at least one intermediate member to be fixed to the transmission housing.

FIG. 1 a view schematically illustrating a vehicular multi-stage transmission structure in one form of the present disclosure.

Referring to FIG. 1 , a vehicular multi-stage transmission includes: an input shaft INPUT and an output shaft OUTPUT; a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , which are provided to be capable of transmitting torque between the input shaft INPUT and the output shaft OUTPUT and each of which includes three rotary elements; and seven shifting elements connected to the rotary elements of the planetary gear devices.

A first rotary element S 1 of the first planetary gear device PG 1 is connected to a second rotary element C 4 of the fourth planetary gear device PG 4 while being fixedly connected to the input shaft INPUT, the second rotary element C 1 of the first planetary gear device PG 1 is selectively connected to a transmission case by one of the seven shifting elements while being selectively connected to the input shaft INPUT, the secondary rotary element C 1 being selectively connected to a third rotary element R 2 of the second planetary gear device PG 2 , a first rotary element S 3 of the third planetary gear device PG 3 , and a first rotary element S 4 of the fourth planetary gear device PG 4 , and the third rotary element R 1 of the first planetary gear device PG 1 is fixedly connected to a second rotary element C 2 of the second planetary gear device PG 2 .

The first rotary element S 2 of the second planetary gear device PG 2 is selectively connected to the second rotary element C 3 of the third planetary gear device PG 3 while being selectively connected to the transmission case by another shifting element of the seven shifting elements.

The second rotary element C 3 of the third planetary gear device PG 3 is connected to the third rotary element R 4 of the fourth planetary gear device PG 4 while being fixedly connected to the output shaft OUTPUT, and the third rotary element R 3 of the third planetary gear device PG 3 is selectively connected to the transmission case by other shifting element of the seven shifting elements.

That is, as the first, second, third, and fourth planetary gear devices are connected between a power input shaft INPUT to which power is input and the power output shaft OUTPUT from which power is output, it is possible to form multiple transmission stages.

In the present disclosure, the first planetary gear device PG 1 , the second planetary gear device PG 2 , the third planetary gear device PG 3 , and the fourth planetary gear device PG 4 may be sequentially arranged along the axial direction of the input shaft INPUT and the output shaft OUTPUT.

The second rotary element C 1 of the first planetary gear device PG 1 may be selectively connected to a transmission case by a first brake B 1 among the shifting elements, the first rotary element of the second planetary gear device PG 2 may be selectively connected to the transmission case by a second brake B 2 among the shifting elements, the third rotary element of the third planetary gear device PG 3 may be selectively fixed to the transmission case by a third brake B 3 among the seven shifting elements, and the remaining elements among the shifting elements may be provided to form a selective connection between the rotary elements of the four planetary gear devices.

Therefore, the first brake B 1 serves to restrain or release the rotation of the second rotary element C 1 of the first planetary gear device PG 1 , the second brake B 2 serves to restrain or release the rotation of the first rotary element S 2 of the second planetary gear device PG 2 , and the third brake B 3 serves to restrain or release the rotation of the third rotary element R 3 of the third planetary gear device PG 3 .

Meanwhile, in one form of the present disclosure, a first clutch CL 1 among the shifting elements may form a selective connection between the second rotary element C 1 of the first planetary gear device PG 1 and the input shaft INPUT, a second clutch CL 2 among the shifting elements may form a selective connection between the second rotary element C 1 of the first planetary gear device PG 1 and the third rotary element R 2 of the second planetary gear device PG 2 , a third clutch CL 3 among the shifting elements may form a selective connection between the first rotary element S 2 of the second planetary gear device PG 2 and the second rotary element C 3 of the third planetary gear device PG 3 , a fourth clutch CL 4 among the shifting elements may form a selective connection between the second rotary element C 4 of the fourth planetary gear device PG 4 and the input shaft INPUT, and the second rotary element C 3 of the third planetary gear device PG 3 may be fixedly connected to the third rotary element R 4 of the fourth planetary gear device PG 4 .

According to another form, it is possible to form a multi-stage transmission structure for a vehicle of the present disclosure. FIG. 2 is a view schematically illustrating a vehicular multi-stage transmission structure according to another form of the present disclosure.

Referring to FIG. 2 , the first clutch CL 1 among the shifting elements may form a selective connection between the second rotary element C 1 of the first planetary gear device PG 1 and the input shaft INPUT, the second clutch CL 2 among the shifting elements may form a selective connection between the second rotary element of the first planetary gear device PG 1 and the third rotary element of the second planetary gear device PG 2 , the third clutch CL 3 among the shifting elements may form a selective connection between the first rotary element of the second planetary gear device PG 2 and the second rotary element of the third planetary gear device PG 3 , the fourth clutch CL 4 among the shifting elements may form a selective connection between the third rotary element of the fourth planetary gear device PG 4 and the output shaft OUTPUT, and the first rotary element of the first planetary gear device PG 1 may be fixedly connected to the second rotary element of the fourth planetary gear device PG 4 .

In the present form, the first rotary element S 1 , the second rotary element C 1 , and the third rotary element R 1 of the first planetary gear device PG 1 are a first sun gear, a first carrier, and a first ring gear, respectively, the first rotary element S 2 , the second rotary element C 2 , and the third rotary element R 2 of the second planetary gear device PG 2 are a second sun gear, a second carrier, and a second ring gear, respectively, the first rotary element S 3 , the second rotary element C 3 , and the third rotary element R 3 of the third planetary gear device PG 3 are a third sun gear, a third carrier, and a third ring gear, respectively, and the first rotary element S 4 , the second rotary element C 4 , and the third rotary element R 4 of the fourth planetary gear device PG 4 are a fourth sun gear, a fourth carrier, and a fourth ring gear, respectively.

The vehicular multi-stage transmission configured as described above may be described as follows.

That is, referring to FIG. 1 , a vehicular multi-stage transmission includes: a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , each of which includes three rotary elements; seven shifting elements configured to variably provide a frictional force; and eight rotary shafts connected to the rotary elements of the planetary gear devices.

The first rotary shaft RS 1 is an input shaft INPUT that is directly connected to the first rotary element of the first planetary gear device PG 1 . The second rotary shaft RS 2 is directly connected to the second rotary element of the first planetary gear device PG 1 , the third rotary shaft RS 3 is directly connected to the third rotary element of the first planetary gear device PG 1 and the second rotary element of the second planetary gear device PG 2 , and the fourth rotary shaft RS 4 is directly connected to the first rotary element of the second planetary gear device PG 2 . The fifth rotary shaft RS 5 is directly connected to the third rotary element of the second planetary gear device PG 2 , the first rotary element of the third planetary gear device PG 3 , and the first rotary element of the fourth rotary gear device PG 4 . The sixth rotary shaft RS 6 is an output shaft OUTPUT directly connected to the second rotary element of the third planetary gear device PG 3 and the third rotary element of the fourth planetary gear device PG 4 . The seventh rotary shaft RS 7 is directly connected to the third rotary element of the third planetary gear device PG 3 , and the eighth rotary shaft RS 8 is directly connected to the second rotary element of the fourth planetary gear device PG 4 .

In addition, the first clutch CL 1 among the seven shifting elements is disposed between the first rotary shaft RS 1 and the second rotary shaft RS 2 , and the second clutch CL 2 is disposed between the second rotary shaft RS 2 and the fifth rotary shaft RS 5 . The third clutch CL 3 is disposed between the fourth shaft RS 4 and the sixth rotary shaft RS 6 , and the fourth clutch CL 4 is disposed between the first rotary shaft RS 1 and the eighth rotary shaft RS 8 . The first brake B 1 is arranged between the second rotary shaft RS 2 and the transmission case, the second brake B 2 is arranged between the fourth rotary shaft RS 4 and the transmission case, and the third brake B 3 is arranged between the seventh rotary shaft RS 7 and the transmission case.

In addition, the first clutch CL 1 is configured to selectively connect the first rotary element S 1 of the first planetary gear device PG 1 and the second rotary element C 1 of the first planetary gear device PG 1 , the second clutch CL 2 is configured to selectively connect the second rotary element C 1 of the first planetary gear device PG 1 , the third rotary element R 2 of the second planetary gear device PG 2 , the first rotary element S 3 of the third planetary gear device PG 3 , and the first rotary element S 4 of the fourth planetary gear device PG 4 , the third clutch CL 3 is configured to selectively connect the first rotary element S 2 of the second planetary gear device PG 2 and the second rotary element C 3 of the third planetary gear device PG 3 , and the fourth clutch CL 4 is configured to selectively connect the first rotary element S 1 of the first planetary gear device PG 1 and the second rotary element C 4 of the fourth planetary gear device PG 4 .

In another form, referring to FIG. 2 , a vehicular multi-stage transmission includes: a first planetary gear device PG 1 , a second planetary gear device PG 2 , a third planetary gear device PG 3 , and a fourth planetary gear device PG 4 , each of which includes three rotary elements; seven shifting elements configured to selectively provide a frictional force; and eight rotary shafts (i.e., first, second, third, fourth, fifth, sixth, seventh and eighth rotary shafts) connected to the rotary elements of the planetary gear devices.

The first rotary shaft RS 1 is an input shaft INPUT that is directly connected to the first rotary element S 1 of the first planetary gear device PG 1 and the secondary rotary element C 4 of the fourth planetary gear device PG 4 . The second rotary shaft RS 2 is directly connected to the second rotary element C 1 of the first planetary gear device PG 1 , the third rotary shaft RS 3 is directly connected to the third rotary element R 1 of the first planetary gear device PG 1 and the second rotary element C 2 of the second planetary gear device PG 2 , and the fourth rotary shaft RS 4 is directly connected to the first rotary element S 2 of the second planetary gear device PG 2 . The fifth rotary shaft RS 5 is directly connected to the third rotary element R 2 of the second planetary gear device PG 2 , the first rotary element S 3 of the third planetary gear device PG 3 , and the first rotary element S 4 of the fourth rotary gear device PG 4 . The sixth rotary shaft RS 6 is an output shaft OUTPUT that is directly connected to the second rotary element C 3 of the third planetary gear device PG 3 . The seventh rotary shaft RS 7 is directly connected to the third rotary element R 3 of the third planetary gear device PG 3 , and the eighth rotary shaft RS 8 is directly connected to the third rotary element R 4 of the fourth planetary gear device PG 4 .

Among the seven shifting elements, a first clutch CL 1 is arranged between the first rotary shaft RS 1 and the second rotary shaft RS 2 , and a second clutch CL 2 is arranged between the second rotary shaft RS 2 and the fifth rotary shaft RS 5 . A third clutch CL 3 is arranged between the fourth shaft RS 4 and the sixth rotary shaft RS 6 , and a fourth clutch CL 4 is arranged between the sixth rotary shaft RS 6 and the eighth rotary shaft RS 8 . A first brake B 1 is disposed between the second rotary shaft RS 2 and the transmission case, a second brake B 2 is disposed between the fourth rotary shaft RS 4 and the transmission case, and a third brake B 3 is disposed between the seventh rotary shaft RS 7 and the transmission case.

In addition, the first clutch CL 1 is configured to selectively connect the first rotary element S 1 of the first planetary gear device PG 1 and the second rotary element C 1 of the first planetary gear device PG 1 , the second clutch CL 2 is configured to selectively connect the second rotary element C 1 of the first planetary gear device PG 1 , the third rotary element R 2 of the second planetary gear device PG 2 , the first rotary element S 3 of the third planetary gear device PG 3 , and the first rotary element S 4 of the fourth planetary gear device PG 4 , the third clutch CL 3 is configured to selectively connect the first rotary element S 2 of the second planetary gear device PG 2 and the second rotary element C 3 of the third planetary gear device PG 3 , and the fourth clutch CL 4 is configured to selectively connect the second rotary element C 3 of the third planetary gear device PG 3 and the third rotary element R 4 of the fourth planetary gear device PG 4 .

Here, the first planetary gear device PG 1 , the second planetary gear device PG 2 , the third planetary gear device PG 3 , and the fourth planetary gear device PG 4 may be sequentially arranged along the axial direction of the input shaft INPUT and the output shaft OUTPUT.

FIGS. 3 and 4 are tables representing operations for respective transmission stages of a vehicular multi-stage transmission according to the present disclosure.

As described above, a vehicular multi-stage transmission including four planetary gear devices and seven shifting elements may implement ten forward stages and one reverse stage according to the operation mode table represented in FIG. 3 . Further, it is also possible to implement twelve forward stages and three reverse stages according to the operation mode table represented in FIG. 4 . In the form of FIG. 4 , it is possible to implement eight forward stages in various ways through the operation of shifting elements.

Therefore, it is possible to realize transmission stages including ten or more forward stages and three or more reverse stages with a relatively small number of components and a simple configuration, thereby contributing to improvement of fuel efficiency and improvement of quietness of the vehicle. Consequently, it is possible to improve the merchantability of the vehicle.

According to the vehicular multi-stage transmission configured to have the above-described structure, the rotary elements, which constitute the first, second, third and fourth planetary gear sets, are shifted while changing the rotational speed and direction by selective operation of the clutches and the brakes, so that the vehicle can be driven by implementing a gear ratio of at least ten forward sages and at least one reverse stage through such a shifting action.

Therefore, by making the automatic transmission have multiple stages, it is possible to improve fuel efficiency, and by using the operating point in a low RPM zone of the engine, it is possible to decrease the running noise of the vehicle.

While the present disclosure has been illustrated and explained in relation to the specific forms thereof, it will be obvious to a person ordinarily skilled in the art that the present disclosure can be variously modified and changed without departing from the scope of the technical idea of the present disclosure.