Patent Publication Number: US-9423008-B2

Title: Multi-stage transmission for vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of Korean Patent Application No. 10-2014-0166834, filed on Nov. 26, 2014, entitled “Multi-Stage Transmission for Vehicle”, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention 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 shifting stages as many as possible by components as small as possible and a simple configuration. 
     2. Description of Related Art 
     Recently, a rise in an oil price has become a factor allowing automobile manufacturers throughout the world to enter into unlimited competition toward fuel efficiency improvement, and in the case of an engine, an effort to improve fuel efficiency and decrease a weight through a technology such as downsizing, or the like, has been conducted. 
     Meanwhile, among methods of improving fuel efficiency that may be made by a transmission mounted in a vehicle, 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 silence of the vehicle. 
     However, as shifting stages of the transmission are increased, the number of internal components configuring the transmission is increased, such that a mounting feature and transfer efficiency may be deteriorated and a cost and a weight may be increased. Therefore, in order to maximize a fuel efficiency improving effect through the multi-stage transmission, it is important to devise a transmission structure capable of deriving maximum efficiency by a small number of components and a comparatively simple configuration. 
     The contents described as the related art have been provided only for assisting in the understanding for the background of the present invention and should not be considered as corresponding to the related art known to those skilled in the art. 
     The information disclosed in this Background of the Invention 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. 
     BRIEF SUMMARY 
     Various aspects of the present invention are directed to providing a multi-stage transmission for a vehicle capable of maximizing fuel efficiency improvement of the vehicle through driving at an optimal driving point of an engine and improving silence of the vehicle through more silent driving of the engine by implementing at least forward ten stages and reverse one stage or more by a comparatively small number of components and a simple configuration. 
     In an aspect of the present invention, a multi-stage transmission for a vehicle, may include an input shaft and an output shaft, a first planetary gear device, a second planetary gear device, a third planetary gear device, and a fourth planetary gear device provided between the input shaft and the output shaft to transfer a torque and each planetary gear device including three rotating elements, and at least six shifting elements connected to the three rotating elements of the first, second, third and fourth planetary gear devices, wherein a first rotating element of the first planetary gear device is selectively connected to a second rotating element of the second planetary gear device, a second rotating element of the first planetary gear device is continuously connected to a third rotating element of the third planetary gear device and is selectively connected to a first rotating element of the second planetary gear device, and a third rotating element of the first planetary gear device, is continuously connected to a third rotating element of the second planetary gear device, wherein the second rotating element of the second planetary gear device is continuously connected to the input shaft, and the third rotating element of the second planetary gear device is continuously connected to a second rotating element of the third planetary gear device and is fixably installed by a first shifting element of the at least six shifting elements, wherein a first rotating element of the third planetary gear device is selectively connected to each of first and second rotating elements of the fourth planetary gear device, and the third rotating element of the third planetary gear device is continuously connected to a third rotating element of the fourth planetary gear device, and wherein the first rotating element of the fourth planetary gear device is fixably installed by a second shifting element of the at least six shifting elements, and the second rotating element of the fourth planetary gear device is continuously 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 are sequentially disposed in an axial direction of the input shaft and the output shaft. 
     The third rotating element of the second planetary gear device is fixably installed to a transmission case by a third clutch among the at least six shifting elements, the first rotating element of the fourth planetary gear device is fixably installed to the transmission case by a fourth clutch among the at least six shifting elements, and remaining shifting elements among the at least six shifting elements are configured to form variable connection structures between the three rotating elements of the first, second, third, and fourth planetary gear devices. 
     A first clutch among the at least six shifting elements forms a variable connection structure between the first rotating element of the first planetary gear device and the second rotating element of the second planetary gear device, a second clutch among the at least six shifting elements forms a variable connection structure between the first rotating element of the third planetary gear device and the second rotating element of the fourth planetary gear device, a fifth clutch among the at least six shifting elements forms a variable connection structure between the first rotating element of the third planetary gear device and the first rotating element of the fourth planetary gear device, and a sixth clutch among the at least six shifting elements forms a variable connection structure between the second rotating element of the first planetary gear device and the first rotating element of the second planetary gear device. 
     In another aspect of the present application, a multi-stage transmission for a vehicle may include a first planetary gear device, a second planetary gear device, a third planetary gear device, and a fourth planetary gear device each having three rotating elements, six shifting elements configured to selectively provide frictional force, and eight shafts connected to the three rotating elements of the first, second, third, and fourth planetary gear devices, wherein a first shaft is an input shaft connected in series with a second rotating element of the second planetary gear device, a second shaft is connected in series with a first rotating element of the first planetary gear device, a third shaft is connected in series with a second rotating element of the first planetary gear device, a third rotating element of the third planetary gear device, and a third rotating element of the fourth planetary gear device, a fourth shaft is connected in series with a third rotating element of the first planetary gear device, a third rotating element of the second planetary gear device, and a second rotating element of the third planetary gear device, a fifth shaft is connected in series with a first rotating element of the second planetary gear device, a sixth shaft is connected in series with a first rotating element of the third planetary gear device, a seventh shaft is connected in series with a first rotating element of the fourth planetary gear device, and an eighth shaft is an output shaft connected in series with a second rotating element of the fourth planetary gear device, and wherein a first clutch among the six shifting elements is installed between the first shaft and the second shaft, a second clutch among the six shifting elements is installed between the sixth shaft and the eighth shaft, a third clutch among the six shifting elements is installed between the fourth shaft and a transmission case, a fourth clutch among the six shifting elements is installed between the seventh shaft and the transmission case, a fifth clutch among the six shifting elements is installed between the sixth shaft and the seventh shaft, and a sixth clutch among the six shifting elements is installed between the third shaft and the fifth shaft. 
     The first planetary gear device, the second planetary gear device, the third planetary gear device, and the fourth planetary gear device are sequentially disposed in an axial direction of the input shaft and the output shaft. 
     The first clutch is installed to selectively connect between the first rotating element of the first planetary gear device and the second rotating element of the second planetary gear device, the second clutch is installed to selectively connect between the first rotating element of the third planetary gear device and the second rotating element of the fourth planetary gear device, the fifth clutch is installed to selectively connect between the first rotating element of the third planetary gear device and the first rotating element of the fourth planetary gear device, and the sixth clutch is installed to selectively connect between the second rotating element of the first planetary gear device and the first rotating element of the second planetary gear device. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram showing a configuration of a multi-stage transmission for a vehicle according to an exemplary embodiment of the present invention. 
         FIG. 2  is a table showing operation modes of the multi-stage transmission for a vehicle of  FIG. 1 . 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     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 the 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. 
     Referring to  FIGS. 1 and 2 , a multi-stage transmission for a vehicle according to an exemplary embodiment of the present invention is configured to include an input shaft IN and an output shaft OUT; 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  provided between the input shaft IN and the output shaft OUT so as to transfer a torque and each including three rotating elements; and at least six shifting elements connected to the rotating elements of the first to fourth planetary gear devices. 
     A first rotating element S 1  of the first planetary gear device PG 1  is selectively connected to a second rotating element C 2  of the second planetary gear device PG 2 , a second rotating element C 1  thereof is continuously connected to a third rotating element R 3  of the third planetary gear device PG 3  and is selectively connected to a first rotating element S 2  of the second planetary gear device PG 2 , and a third rotating element R 1  thereof is continuously connected to a third rotating element R 2  of the second planetary gear device PG 2 . 
     The second rotating element C 2  of the second planetary gear device PG 2  is continuously connected to the input shaft IN, and the third rotating element R 2  thereof is continuously connected to a second rotating element C 3  of the third planetary gear device PG 3  and is fixably installed by any one of the shifting elements. 
     A first rotating element S 3  of the third planetary gear device PG 3  is selectively connected to each of first and second rotating elements S 4  and C 4  of the fourth planetary gear device PG 4 , and the third rotating element R 3  thereof is continuously connected to a third rotating element R 4  of the fourth planetary gear device PG 4 . 
     The first rotating element S 4  of the fourth planetary gear device PG 4  is fixably installed by another of the shifting elements, and the second rotating element C 4  thereof is continuously connected to the output shaft OUT. 
     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  are sequentially disposed in an axial direction of the input shaft IN and the output shaft OUT. 
     The third rotating element R 2  of the second planetary gear device PG 2  is fixably installed to a transmission case CS by a third clutch CL 3  among the shifting elements; and the first rotating element S 4  of the fourth planetary gear device PG 4  is fixably installed to the transmission case CS by a fourth clutch CL 4  among the shifting elements. 
     That is, the third clutch CL 3  and the fourth clutch CL 4  among the shifting elements serve as brakes, respectively, to serve to restrict or allow rotation of the third rotating element R 2  of the second planetary gear device PG 2  and the first rotating element S 4  of the fourth planetary gear device PG 4 , respectively. 
     The others among the shifting elements are configured so as to form variable connection structures between the rotating elements of the planetary gear devices. 
     That is, a first clutch CL 1  among the shifting elements forms the variable connection structure between the first rotating element S 1  of the first planetary gear device PG 1  and the second rotating element C 2  of the second planetary gear device PG 2 ; a second clutch CL 2  among the shifting elements forms the variable connection structure between the first rotating element S 3  of the third planetary gear device PG 3  and the second rotating element C 4  of the fourth planetary gear device PG 4 ; a fifth clutch CL 5  among the shifting elements forms the variable connection structure between the first rotating element S 3  of the third planetary gear device PG 3  and the first rotating element S 4  of the fourth planetary gear device PG 4 ; and a sixth clutch CL 6  among the shifting elements forms the variable connection structure between the second rotating element C 1  of the first planetary gear device PG 1  and the first rotating element S 2  of the second planetary gear device PG 2 . 
     In the present exemplary embodiment, the first rotating element S 1 , the second rotating element C 1 , and the third rotating 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 rotating element S 2 , the second rotating element C 2 , and the third rotating 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 rotating element S 3 , the second rotating element C 3 , and the third rotating 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 rotating element S 4 , the second rotating element C 4 , and the third rotating 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 described above may also be represented as follows. 
     That is, the multi-stage transmission for a vehicle according to an exemplary embodiment of the present invention is configured to include 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  each having three rotating elements; the six shifting elements configured so as to selectively provide frictional force; and eight shafts connected to the rotating elements of the planetary gear devices. 
     Here, a first shaft RS 1  is the input shaft IN connected in series with the second rotating element C 2  of the second planetary gear device PG 2 ; a second shaft RS 2  is connected in series with the first rotating element S 1  of the first planetary gear device PG 1 ; a third shaft RS 3  is connected in series with the second rotating element C 1  of the first planetary gear device PG 1 , the third rotating element R 3  of the third planetary gear device PG 3 , and the third rotating element R 4  of the fourth planetary gear device PG 4 ; a fourth shaft RS 4  is connected in series with the third rotating element R 1  of the first planetary gear device PG 1 , the third rotating element R 2  of the second planetary gear device PG 2 , and the second rotating element C 3  of the third planetary gear device PG 3 ; a fifth shaft RS 5  is connected in series with the first rotating element S 2  of the second planetary gear device PG 2 ; a sixth shaft RS 6  is connected in series with the first rotating element S 3  of the third planetary gear device PG 3 ; a seventh shaft RS 7  is connected in series with the first rotating element S 4  of the fourth planetary gear device PG 4 ; and an eighth shaft RS 8  is the output shaft OUT connected in series with the second rotating element C 4  of the fourth planetary gear device PG 4 . 
     In addition, the first clutch CL 1  among the six shifting elements is installed between the first shaft RS 1  and the second shaft RS 2 , the second clutch CL 2  among the six shifting elements is installed between the sixth shaft RS 6  and the eighth shaft RS 8 , the third clutch CL 3  among the six shifting elements is installed between the fourth shaft RS 4  and the transmission case CS, the fourth clutch CL 4  among the six shifting elements is installed between the seventh shaft RS 7  and the transmission case CS, the fifth clutch CL 5  among the six shifting elements is installed between the sixth shaft RS 6  and the seventh shaft RS 7 , and the sixth clutch CL 6  among the six shifting elements is installed between the third shaft RS 3  and the fifth shaft RS 5 . 
     Since the multi-stage transmission for a vehicle according to an exemplary embodiment of the present invention including the four simple planetary gear devices and the six shifting elements as described above may implement forward ten stages and reverse one stage depending on an operation mode table as shown in  FIG. 2 , it may implement a multi-stage shifting stage of ten stages by a relatively small number of components and a simple configuration to contribute to improvement of fuel efficiency and silence of the vehicle, thereby making it possible to improve salability of the vehicle. 
     As set forth above, according to exemplary embodiment of the present invention, at least forward ten stages and reverse one stage or more are implemented by a comparatively small number of components and a simple configuration, thereby making it possible to maximize fuel efficiency improvement of the vehicle through driving at an optimal driving point of an engine and improve silence of the vehicle through more silent driving of the engine. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     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.