Multi-stage transmission for vehicle

The present application claims priority of Korean Patent Application Number 10-2015-0080474 filed Jun. 8, 2015, the entire contents of which application are incorporated herein for all purposes by this reference

The present invention generally relates to a multi-stage transmission for a vehicle and, more particularly, to a multi-stage transmission able to realize highest possible number of shifting stages using fewer parts and simple configuration, thereby improving fuel efficiency of a vehicle.

Recent rising oil prices have driven worldwide car manufacturers into unlimited competition to improve fuel efficiency. In addition, great efforts have been made to reduce the weight and improve the fuel efficiency of engines based on a variety of techniques such as downsizing.

Meanwhile, among methods that can be sought for transmissions equipped in vehicles to improve fuel efficiency, there is a method allowing an engine to operate at more efficient operation points using the multi-staging of a transmission, thereby ultimately improving the fuel efficiency.

Further, such a multi-staging of a transmission allows an engine to be operated in a relatively low RPM (revolutions per minute) range, thereby further improving the quietness of a vehicle.

However, as the number of shifting stages of a transmission increases, the number of internal parts constituting the transmission also increases. This may lead to undesirable effects instead, such as the reduced mountability and transfer efficiency and the increased cost and weight of the transmission. Therefore, in order to maximize the effect of the improved fuel efficiency using the multi-staging of a transmission, it is important to devise a transmission structure able to realize maximum efficiency using a smalle number of parts and a relatively simple configuration.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art and/or other problems, and the present invention is intended to provide a multi-stage transmission for a vehicle that is able to realize at least eleven forward shifting stages and one reverse shifting stage with a relatively small number of parts and a simple configuration such that an engine may be operated at optimum operation points, thereby maximizing an improvement in the fuel efficiency of the vehicle, and the engine may be operated more quietly, thereby improving the quietness of the vehicle.

In order to achieve the above object and/or other objects, a multi-stage transmission for a vehicle according to the present invention may include: an input shaft; an output shaft; first, second, third and fourth planetary gear devices disposed between the input shaft and the output shaft to transmit rotary forces, each of the first to fourth planetary gear devices having three rotary elements; and at least six shifting elements connected to the rotary elements of the planetary gear devices. A first rotary element of the first planetary gear device may be installed to be fixable by one shifting element of the at least six shifting elements and permanently connected to a second rotary element of the third planetary gear device and a third rotary element of the fourth planetary gear device, a second rotary element of the first planetary gear device may be variably connected to a third rotary element of the second planetary gear device and a third rotary element of the third planetary gear device, and a third rotary element of the first planetary gear device may be variably connected to a first rotary element and a second rotary element of the second planetary gear device. The first rotary element of the second planetary gear device may be installed to be fixable by another shifting element of the at least six shifting elements, the second rotary element of the second planetary gear device may be permanently connected to the input shaft, and the third rotary element of the second planetary gear device may be permanently connected to a first rotary element of the third planetary gear device. The first rotary element of the third planetary gear device may be permanently connected to a first rotary element of the fourth planetary gear device. A second rotary element of the fourth planetary gear device may be permanently connected to the output shaft.

The first planetary gear device, the second planetary gear device, the third planetary gear device and the fourth planetary gear device may be sequentially arranged along an axial direction of the input shaft or the output shaft.

The first rotary element of the first planetary gear device may be installed to be fixable to a transmission case by means of a first brake of the at least six shifting elements, the first rotary element of the second planetary gear device may be installed to be fixable to the transmission case by means of a second brake of the at least six shifting elements, and the other shifting elements of the at least six shifting elements may be configured to constitute variable connection structures between the rotary elements of the planetary gear devices.

A first clutch of the at least six shifting elements may form a variable connection structure between the third rotary element of the first planetary gear device and the first rotary element of the second planetary gear device; a second clutch of the at least six shifting elements may form a variable connection structure between the third rotary element of the first planetary gear device and the second rotary element of the second planetary gear device; a third clutch of the at least six shifting elements may form a variable connection structure between the second rotary element of the first planetary gear device and the third rotary element of the second planetary gear device; and a fourth clutch of the at least six shifting elements may form a variable connection structure between the second rotary element of the first planetary gear device and the third rotary element of the third planetary gear device.

In some aspects, a multi-stage transmission for a vehicle according to the present invention may include: first, second, third and fourth planetary gear devices each having three rotary elements, respectively; at least six shifting elements configured to variably provide frictional forces; and first, second, third, fourth, fifth, sixth, seventh and eighth rotary shafts connected to the rotary elements of the first, second, third and fourth planetary gear devices, wherein the first rotary shaft is an input shaft directly connected to a second rotary element of the second planetary gear device, the second rotary shaft is directly connected to a first rotary element of the first planetary gear device, a second rotary element of the third planetary gear device and a third rotary element of the fourth planetary gear device, the third rotary shaft is directly connected to a second rotary element of the first planetary gear device, the fourth rotary shaft is directly connected to a third rotary element of the first planetary gear device, the fifth rotary shaft is directly connected to a first rotary element of the second planetary gear device, the sixth rotary shaft is directly connected to a third rotary element of the second planetary gear device, a first rotary element of the third planetary gear device and a first rotary element of the fourth planetary gear device, the seventh rotary shaft is directly connected to a third rotary element of the third planetary gear device, and the eighth rotary shaft is an output shaft directly connected to a second rotary element of the fourth planetary gear device; and wherein the at least six shifting elements include first, second, third and fourth clutches and first and second brakes, the first clutch is disposed between the fourth rotary shaft and the fifth rotary shaft, the second clutch is disposed between the first rotary shaft and the fourth rotary shaft, the third clutch is disposed between the third rotary shaft and the sixth rotary shaft, the fourth clutch is disposed between the third rotary shaft and the seventh rotary shaft, the first brake is disposed between the second rotary shaft and a transmission case, the second brake is disposed between the fifth rotary shaft and the transmission case.

The first planetary gear device, the second planetary gear device, the third planetary gear device and the fourth planetary gear device may be sequentially arranged along an axial direction of the input shaft or the output shaft.

The first clutch of the at least six shifting elements may form a variable connection structure between the third rotary element of the first planetary gear device and the first rotary element of the second planetary gear device; the second clutch of the at least six shifting elements may form a variable connection structure between the third rotary element of the first planetary gear device and the second rotary element of the second planetary gear device; the third clutch of the at least six shifting elements may form a variable connection structure between the second rotary element of the first planetary gear device and the third rotary element of the second planetary gear device; the fourth clutch of the at least six shifting elements may form a variable connection structure between the second rotary element of the first planetary gear device and the third rotary element of the third planetary gear device; the first brake of the at least six shifting elements may form a variable connection structure between the first rotary element of the first planetary gear device and the transmission case; and the second brake of the at least six shifting elements may form a variable connection structure between the first rotary element of the second planetary gear device and the transmission case.

According to the present invention as set forth above, the multi-stage transmission for a vehicle can realize at least eleven forward shifting stages and one reverse shifting stage with a relatively small number of parts and a simple configuration such that the engine may be operated at optimum operation points, thereby maximizing an improvement in the fuel efficiency of the vehicle, and the engine may be operated more quietly, thereby improving the quietness of the vehicle.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

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

FIG. 2 illustrates an operation mode table of the transmission shown in FIG. 1 .

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.

Referring to FIG. 1 , a multi-stage transmission for a vehicle according to an exemplary embodiment of the present invention may include an input shaft IN; an output shaft OUT; first to fourth planetary gear devices PG 1 , PG 2 , PG 3 and PG 4 disposed between the input shaft IN and the output shaft OUT to transmit rotary forces, each of the first to fourth planetary gear devices PG 1 to PG 4 having three rotary elements; and at least six shifting elements connected to rotary elements of the first to fourth planetary gear devices PG 1 to PG 4 .

A first rotary element S 1 of the first planetary gear device PG 1 installed to be fixable by one shifting element of the at least six shifting elements and permanently connected to a second rotary element C 3 of the third planetary gear device PG 3 and a third rotary element R 4 of the fourth planetary gear device PG 4 . A second rotary element C 1 of the first planetary gear device PG 1 may be variably connected to a third rotary element R 2 of the second planetary gear device PG 2 and a third rotary element R 3 of the third planetary gear device PG 3 . A third rotary element R 1 of the first planetary gear device PG 1 may be variably connected to a first rotary element S 2 and a second C 2 of the second planetary gear device PG 2 .

The first rotary element S 2 of the second planetary gear device PG 2 may be installed to be fixable by another shifting element of the at least six shifting elements, the second rotary element C 2 of the second planetary gear device PG 2 may be permanently connected to the input shaft IN, and the third rotary element R 2 of the second planetary gear device PG 2 may be variably connected to the first rotary element S 3 of the third planetary gear device PG 3 .

The first rotary element S 3 of the third planetary gear device PG 3 may be permanently connected to a first rotary element S 4 of the fourth planetary gear device PG 4 . A second rotary element C 4 of the fourth planetary gear device PG 4 may be permanently connected to the output shaft OUT.

In the present exemplary embodiment, 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 IN and/or the output shaft OUT.

The first rotary element S 1 of the first planetary gear device PG 1 may be installed to be fixable to the transmission case CS by means of a first brake B 1 of the at least six shifting elements. The first rotary element S 2 of the second planetary gear device PG 2 may be installed to be fixable to the transmission case CS by means of a second brake B 2 of the at least six shifting elements.

The other shifting elements of the at least six shifting elements may be configured to constitute variable connection structures between the rotary elements of the planetary gear devices.

For example, a first clutch CL 1 of the at least six shifting elements may form a variable connection structure between the third rotary element R 1 of the first planetary gear device PG 1 and the first rotary element S 2 of the second planetary gear device PG 2 . A second clutch CL 2 of the at least six shifting elements may form a variable connection structure between 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 . A third clutch CL 3 of the at least six shifting elements may form a variable connection structure 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 fourth clutch CL 4 of the at least six shifting elements may form a variable connection structure between the second rotary element C 1 of the first planetary gear device PG 1 and the third rotary element R 3 of the third planetary gear device PG 3 .

In the present exemplary embodiment, 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. 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 multi-stage transmission for a vehicle configured as above may also be presented as follows.

Specifically, the multi-stage transmission for a vehicle according to the present invention may include the first to fourth planetary gear devices PG 1 to PG 4 each having the three rotary elements; the six shifting elements configured to variably provide frictional force; and eight rotary shafts connected to the rotary elements of the first to fourth planetary gear devices PG 1 to PG 4 .

Hence, of the eight rotary shafts, the first rotary shaft RS 1 may be the input shaft IN directly connected to the second rotary element C 2 of the second planetary gear device PG 2 . The second rotary shaft RS 2 may be directly connected to the first rotary element S 1 of the first planetary gear device PG 1 , 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 . The third rotary shaft RS 3 may be directly connected to the second rotary element C 1 of the first planetary gear device PG 1 . The fourth rotary shaft RS 4 may be directly connected to the third rotary element R 1 of the first planetary gear device PG 2 . The fifth rotary shaft RS 5 may be directly connected to the first rotary element S 2 of the second planetary gear device PG 2 . The sixth rotary shaft RS 6 may be 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 planetary gear device PG 4 . The seventh rotary shaft RS 7 may be directly connected to the third rotary element R 3 of the third planetary gear device PG 3 . The eighth rotary shaft RS 8 may be the output shaft OUT directly connected to the second rotary element C 4 of the fourth planetary gear device PG 4 .

In addition, of the six shifting elements, the first clutch CL 1 may be disposed between the fourth rotary shaft RS 4 and the fifth rotary shaft RS 5 . The second clutch CL 2 may be disposed between the first rotary shaft RS 1 and the fourth rotary shaft RS 4 . The third clutch CL 3 may be disposed between the third rotary shaft RS 3 and the sixth rotary shaft RS 6 . The fourth clutch CL 4 may be disposed between the third rotary shaft RS 3 and the seventh rotary shaft RS 7 . The first brake B 1 may be disposed between the second rotary shaft RS 2 and the transmission case CS. The second brake B 2 may be disposed between the fifth rotary shaft RS 5 and the transmission case CS.

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 IN and/or the output shaft OUT.

A first clutch CL 1 of the at least six shifting elements may form a variable connection structure between the third rotary element R 1 of the first planetary gear device PG 1 and the first rotary element S 3 of the third planetary gear device PG 3 . A second clutch CL 2 of the at least six shifting elements may form a variable connection structure between 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 . A third clutch CL 3 of the at least six shifting elements may form a variable connection structure 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 fourth clutch CL 4 of the at least six shifting elements may form a variable connection structure between the second rotary element C 1 of the first planetary gear device PG 1 and the third rotary element R 3 of the third planetary gear device PG 3 . The first brake B 1 may form a variable connection structure between the first rotary element S 1 of the first planetary gear device PG 1 and the transmission case CS. The second brake B 2 may form a variable connection structure between the first rotary element S 2 of the second planetary gear device PG 2 and the transmission case CS.

As set forth above, the multi-stage transmission for a vehicle according to the present invention including the four simple planetary gear devices and the six shifting elements realizes eleven forward shifting stages and one reverse shifting stage according to the operation mode table as illustrated in FIG. 2 . Since the multi-stage shifting stages of ten shifting stages can be embodied based on a relatively small number of parts and a simple configuration, the multi-stage transmission for a vehicle can contribute to the improved fuel efficiency and quietness of a vehicle, thereby ultimately improving the marketability of the vehicle.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.