Multi stage transmission for vehicle

The present application claims priority to Korean Patent Application No. 10-2017-0125748, filed on Sep. 28, 2017, the entire contents of which is incorporated herein by reference.

1. Technical Field

The present disclosure relates to a multi-stage transmission for a vehicle, and more particularly, to a technology capable of improving fuel efficiency of a vehicle by implementing a multi shift stage of ten forward stages and one rearward stage.

2. Description of the Related Art

Recently, a rise in oil prices has motivated automobile manufacturers throughout the world to compete with respect to improvements in fuel efficiency. Further, efforts have been made to improve engine fuel efficiency and decrease engine weight through technology such as downsizing.

Meanwhile, as to improving fuel efficiency of a vehicle transmission, there is a method of allowing an engine to be driven at a more efficient driving point through a multi-stage transmission to ultimately improve fuel efficiency.

In addition, the multi-stage transmission as described above may allow the engine to be driven in a relatively low revolution per minute (RPM) band to further improve the noise level generated by the vehicle.

However, as shift stages of the transmission are increased, the number of internal components configuring the transmission is also increased. As a result, there may be difficulty in loading the transmission into the engine compartment and the transfer efficiency of the transmission may be deteriorated while cost and weight may be increased. Therefore, in order to maximize fuel efficiency through the multi-stage transmission, it is important to devise a transmission structure capable of deriving maximum efficiency using a small number of components and a relatively straightforward configuration.

The contents described as the related art have been provided only for assisting in the understanding for the background of the present disclosure and should not be considered as corresponding to the related art known to those skilled in the art.

One aspect of the present disclosure is to provide a multi-stage transmission for a vehicle capable of maximizing fuel efficiency of the vehicle through driving an engine at an optimal driving point and improving the noise level generated by the vehicle through a more quiet operation of the engine by implementing in the engine ten forward stages and one rearward stage with a relatively small number of components and a straightforward configuration.

According to an exemplary embodiment of the present disclosure, there is provided a multi-stage transmission for a vehicle, including: an input shaft IN to which power of an engine is transferred; an output shaft OUT outputting the power; a first planetary gear set PG 1 , a second planetary gear set PG 2 , a third planetary gear set PG 3 , and a fourth planetary gear set PG 4 , each having three rotary elements; a first rotary shaft RS 1 connected to the input shaft IN; a second rotary shaft RS 2 connected to a second rotary element of the first planetary gear set PG 1 and a third rotary element of the second planetary gear set PG 2 ; a third rotary shaft RS 3 connected to a first rotary element of the third planetary gear set PG 3 ; a fourth rotary shaft RS 4 connected to a first rotary element of the first planetary gear set PG 1 , a first rotary element of the second planetary gear set PG 2 , and a third rotary element of the third planetary gear set PG 3 ; a fifth rotary shaft RS 5 connected to a second rotary element of the second planetary gear set PG 2 ; a sixth rotary shaft RS 6 connected to a third rotary element of the first planetary gear set PG 1 , a second rotary element of the third planetary gear set PG 3 , and a third rotary element of the fourth planetary gear set PG 4 ; a seventh rotary shaft RS 7 connected to a first rotary element of the fourth planetary gear set PG 4 ; and an eighth rotary shaft RS 8 connected to a second rotary element of the fourth planetary gear set PG 4 and the output shaft OUT.

The multi-stage transmission may further include: four clutches that interconnect two rotary shafts among eight rotary shafts; and two brakes for selectively connecting a rotary shaft of the eight rotary shafts that is not connected to the input shaft IN or the output shaft OUT and a transmission housing CS.

The four clutches may include a first clutch CL 1 installed between the first rotary shaft RS 1 and the second rotary shaft RS 2 ; a second clutch CL 2 installed between the first rotary shaft RS 1 and the second rotary shaft RS 2 ; a third clutch CL 3 installed between the fourth rotary shaft RS 4 and the seventh rotary shaft RS 7 ; and a fourth clutch CL 4 installed between the fourth rotary shaft RS 4 and the eighth rotary shaft RS 8 , and the two brakes may include a first brake B 1 installed between the fifth rotary shaft RS 5 and the transmission case CS; and a second brake B 2 installed between the seventh rotary shaft RS 7 and the transmission case CS.

The first, second and third rotary elements of the first planetary gear set PG 1 may be configured of a first sun gear, a first carrier, and a first ring gear. The first, second, third rotary elements of the second planetary gear set PG 2 may be configured of a second sun gear, a second carrier, and a second ring gear. The first, second and third rotary elements of the third planetary gear set PG 3 may be configured of a third sun gear, a third carrier, and a third ring gear. The first, second and third rotary elements of the fourth planetary gear set PG 4 may be configured of a fourth sun gear, a fourth carrier, and a fourth ring gear.

FIG. 1 is a configuration diagram of a multi-stage transmission for a vehicle according to an exemplary embodiment of the present disclosure.

FIG. 2 is an operation mode table describing that each shift stage is implemented by the transmission of FIG. 1 .

Referring to FIG. 1 , a multi-stage transmission for a vehicle according to an exemplary embodiment of the present disclosure is configured to include an input shaft IN and an output shaft OUT; a first planetary gear set PG 1 , a second planetary gear set PG 2 , a third planetary gear set PG 3 , and a fourth planetary gear set PG 4 installed between the input shaft IN and the output shaft OUT so as to transfer a torque and each including three rotary elements; and six shifting elements connected to the rotary elements of the first to fourth planetary gear sets.

In particular, the multi-stage transmission for a vehicle includes: a first rotary shaft RS 1 connected to the input shaft IN; a second rotary shaft RS 2 connected to a second rotary element C 1 of the first planetary gear set PG 1 and a third rotary element R 2 of the second planetary gear set PG 2 ; a third rotary shaft RS 3 connected to a first rotary element S 3 of the third planetary gear set PG 3 ; a fourth rotary shaft RS 4 connected to a first rotary element S 1 of the first planetary gear set PG 1 , a first rotary element S 2 of the second planetary gear set PG 2 , and a third rotary element R 3 of the third planetary gear set PG 3 ; a fifth rotary shaft RS 5 connected to a second rotary element C 2 of the second planetary gear set PG 2 ; a sixth rotary shaft RS 6 connected to a third rotary element R 1 of the first planetary gear set PG 1 , a second rotary element C 3 of the third planetary gear set PG 3 , and a third rotary element R 4 of the fourth planetary gear set PG 4 ; a seventh rotary shaft RS 7 connected to a first rotary element S 4 of the fourth planetary gear set PG 4 ; and an eighth rotary shaft RS 8 connected to a second rotary element C 4 of the fourth planetary gear set PG 4 and the output shaft OUT.

The first planetary gear set PG 1 , the second planetary gear set PG 2 , the third planetary gear set PG 3 , and the fourth planetary gear set PG 4 are sequentially disposed in an axial direction from the input shaft IN toward the output shaft OUT.

The transmission elements include: four clutches that interconnect two rotary shafts among eight rotary shafts; and two brakes for selectively connecting a rotary shaft not connected to the input shaft IN or the output shaft OUT among the eight rotary shafts and the transmission housing CS.

Specifically, the four clutches include a first clutch CL 1 installed between the first rotary shaft RS 1 and the second rotary shaft RS 2 ; a second clutch CL 2 installed between the first rotary shaft RS 1 and the third rotary shaft RS 3 ; a third clutch CL 3 installed between the fourth rotary shaft RS 4 and the seventh rotary shaft RS 7 ; and a fourth clutch CL 4 installed between the fourth rotary shaft RS 4 and the eighth rotary shaft RS 8 .

The two brakes include a first brake B 1 installed between the fifth rotary shaft RS 5 and the transmission case CS; and a second brake B 2 installed between the seventh rotary shaft RS 7 and the transmission case CS.

That is, the second rotary element C 2 of the second planetary gear set PG 2 may be connected to the transmission case CS by the first brake B 1 to be controlled in a fixed state or a freely rotatable state. The first rotary element S 4 of the fourth planetary gear set PG 4 may be connected to the transmission case CS by the second brake B 2 to be controlled in a fixed state or a freely rotatable state.

The first brake B 1 and the second brake B 2 , the first clutch CL 1 , the second clutch CL 2 , the third clutch CL 3 , and the fourth clutch CL 4 are all controlled by a controller (not illustrated) according to the operation mode table as illustrated in FIG. 2 , so that a total of ten forward stages and one rearward stage of the vehicle are available.

The first brake B 1 , the second brake B 2 , the first clutch CL 1 , the second clutch CL 2 , the third clutch CL 3 , and the fourth clutch CL 4 are collectively referred to as a “shifting element.” In particular, the transmission of the present disclosure is configured to realize a so-called clutch-to-clutch shift, which performs shifting by engaging another shifting element while releasing one shifting element upon a series of shifting from first stage to tenth stage, as illustrated in FIG. 2 .

The first, second and third rotary elements of the first planetary gear set PG 1 are configured of a first sun gear, a first carrier, and a first ring gear. The first, second, and third rotary elements of the second planetary gear set PG 2 are configured of a second sun gear, a second carrier, and a second ring gear. The first, second and third rotary elements of the third planetary gear set PG 3 are configured of a third sun gear, a third carrier, and a third ring gear. The first, second and third rotary elements of the fourth planetary gear set PG 4 are configured of a fourth sun gear, a fourth carrier, and a fourth ring gear.

As described above, the multi-stage transmission of the present disclosure configured with four simple planetary gear sets and six shifting elements may implement ten forward stages and one rearward stage according to the operation mode table, as illustrated in FIG. 2 . Thus, the multi shift stage of ten stages may be realized with a relatively small number of components, a straightforward configuration, and a low weight. As a result, it is possible to improve the fuel efficiency of the vehicle by providing a more optimized shifting ratio to the driving condition of the vehicle.

As set forth above, according to an exemplary embodiment of the present disclosure, ten forward stages and one rearward stage are implemented by a relatively small number of components and a straightforward configuration, thereby maximizing fuel efficiency of the vehicle by driving the engine at an optimal driving point and improving the noise level generated by the vehicle by a more quiet operation of the engine.

Although the present disclosure has been shown and described with respect to specific exemplary embodiments, it will be obvious to those skilled in the art that the present disclosure may be variously modified and altered without departing from the spirit and scope of the present disclosure as defined by the following claims.