Abstract:
A hybrid power train for vehicles uses a double clutch transmission (DCT) to further improve the fuel efficiency of a vehicle, obtain a sporty transmission, and prevent the entire length thereof from being excessively lengthened, thereby sufficiently securing the ability of being mounted in a vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority of Korean Patent Application Number 10-2011-0094015 filed Sep. 19, 2011, the entire contents of which application is incorporated herein for all purposes by this reference. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates, in general, to a hybrid power train for vehicles, and more particularly, to a structure of a power train for hybrid vehicles, using a double clutch transmission 
         [0004]    2. Description of Related Art 
         [0005]    In order to cope with the increase in oil prices and the regulations concerning CO 2  in the environment that have recently increased, there is an actual need to further improve the fuel efficiency of vehicles. At the present time, improving the efficiency of a drive system which plays a part in the power transmission and improving the efficiency of an internal engine may be the most practical way to deal with such a need. 
         [0006]    The most efficient transmission in conventional driving systems is a manual transmission. Since the transmission efficiency of a double clutch transmission (DCT) designed based on this manual transmission is superior to that of an automatic transmission (AT) or a continuously variable transmission (CVT), if a hybrid type transmission in which such an efficient DCT and an electric motor are combined together is designed, the fuel efficiency of the currently available internal engines can be further improved. 
         [0007]    However, a conventional hybrid power train has a structure in which as shown in  FIG. 1 , an electric motor  504  is inserted between an engine  500  and a transmission  502 , so that the length of the transmission shown in  FIG. 1  becomes longer than that of the conventional AT or CVT since the structure of a conventional DCT generally is such that two clutches are disposed in an overlapped fashion in an axial direction. Such a structure makes much the entire length of a mounting space for the engine  500  and transmission longer, thereby reducing its ability to be mounted in a vehicle. 
         [0008]    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. 
       SUMMARY OF INVENTION 
       [0009]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention proposes a hybrid power train for vehicles which use a double clutch transmission (DCT) so as to further improve fuel efficiency of a vehicle, obtain sporty transmission, and avoid making much lengthy the entire length thereof, thereby sufficiently securing the ability of being mounted to a vehicle. 
         [0010]    Various aspects of the present invention provide for a hybrid power train for vehicles including an input shaft having a driving gear, first and second driven gears respectively meshing with the driving gear, a first driving shaft concentrically connected to the first driven gear in the medium of a first clutch such that it is disposed parallel with the input shaft, a second driving shaft concentrically connected to the second driven gear in the medium of a second clutch such that it is disposed parallel with the input shaft, an output shaft disposed parallel with the first and second driving shafts, a plurality transmission driving gears respectively provided on the first and second driving shafts such that they respectively mesh with a plurality of transmission driven gears provided on the output shaft so as to obtain a multistage speed, a plurality of synchronizing devices enabling the plurality of transmission driving gears to synchronously mesh with the first or second driving shaft, and an electric motor having a rotary shaft disposed parallel with the first driving shaft, second driving shaft, and output shaft so as to provide power to the driving gear. 
         [0011]    According to a hybrid power train for vehicles using a double clutch transmission, fuel efficiency of a vehicle is further improved, a sporty transmission is obtained, and the entire length thereof is prevented from being excessively lengthened, thereby sufficiently securing the ability of being mounted in a vehicle. 
         [0012]    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 
         [0013]      FIG. 1  is a view showing the structure of a hybrid power train according to the related art. 
           [0014]      FIG. 2  is a view showing an exemplary hybrid power train for vehicles according to the present invention. 
           [0015]      FIGS. 3 and 4  are views observing  FIG. 2  in a side view for schematically explaining the connective relation between shafts. 
           [0016]      FIG. 5  is a view showing an exemplary hybrid power train for vehicles according to the present invention. 
           [0017]      FIGS. 6 to 8  are views showing the operation of the hybrid power train of  FIG. 5 . 
           [0018]      FIG. 9  is a view showing an exemplary hybrid power train for vehicles according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    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. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 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. 
         [0020]    Referring to  FIG. 2 , a hybrid power train for vehicles according to various embodiments of the present invention includes: an input shaft  3  having a driving gear  1 ; first and second driven gears  5  and  7  respectively meshing with the driving gear  1 ; a first driving shaft  11  concentrically connected to the first driven gear  5  in the medium of a first clutch  9  such that it is disposed parallel with the input shaft  3 ; a second driving shaft  15  concentrically connected to the second driven gear  7  in the medium of a second clutch  13  such that it is disposed parallel with the input shaft  3 ; an output shaft  17  disposed parallel with the first and second driving shafts  11  and  15 ; a plurality transmission driving gears  21  respectively provided on the first and second driving shafts  11  and  15  such that they respectively mesh with a plurality of transmission driven gears  19  provided on the output shaft  17  so as to obtain a multistage speed; a plurality of synchronizing devices  23  enabling the plurality of transmission driving gears  21  to synchronously mesh with the first or second driving shaft  11  or  15 ; and an electric motor  25  having a rotary shaft disposed parallel with the first driving shaft  11 , second driving shaft  15 , and output shaft  17  so as to provide power to the driving gear  1 . 
         [0021]    The electric motor  25 , first driving shaft  11 , second driving shaft  15 , and output shaft  17  overlap each other as much as possible so that they are arranged within the range defined by the longest shaft among them. The rotary shaft of the electric motor  25 , first driving shaft  11 , second driving shaft  15 , and output shaft  17  are arranged in a rectangular structure. 
         [0022]    That is, the electric motor, which is provided to supply power and the driving force, apart from an engine  27 , is arranged such that it overlaps adjacent to the first driving shaft  11 , second driving shaft  15 , and output shaft  17  while being parallel with them, consequently resulting in all the former elements being arranged within the range defined by the longest element among them, thereby shortening by as much as possible the axial length of the transmission mechanism and electric motor. 
         [0023]    Moreover, the first clutch  9  and second clutch  13 , and the first input shaft  3  and second input shaft  3  enable the operation of a double clutch transmission (DCT) by selectively transmitting power supplied from the driving gear  1  by individually using the first and second clutches  9  and  13 . In addition, they make the axial length shorter than in the case where conventional clutches overlap in the axial direction, thereby eventually minimizing the axial length defined by a transmission and electric motor  25 . 
         [0024]      FIGS. 3 and 4  show the arrangement of the respective rotary shafts in a side view of the construction of  FIG. 2 . In  FIG. 3 , the rotary shaft of the electric motor  25  is integrally coupled with the input shaft  3  having the driving gear  1 , concentrically with respect thereto. One will appreciate that the rotary shaft may be monolithically formed with the input shaft. In  FIG. 4 , a pinion  29  is coupled to the rotary shaft of the electric motor  25  such that it meshes with the driving gear  1 , which means that the rotary shafts of the electric motor  25  and driving gear  1  may be arranged in a concentric or non-concentric manner with respect to each other. 
         [0025]    The engine  27  is connected to the input shaft  3  having the driving gear  1  via a main clutch  31 , so that the rotary shaft of the electric motor  25  is concentrically mounted to the engine according to various embodiments, or otherwise it is arranged with the engine in a parallel, but non-concentric manner with respect to the engine. 
         [0026]    In various embodiments, besides the main clutch  31 , a damper  33  is disposed between the engine  27  and the driving gear  1  in order to offset distortion vibrations of the engine  27 . The main clutch  31  that is illustrated consists of two clutches on opposite sides of the damper  33 , but it may consist of either of two clutches. 
         [0027]    For reference, similar to the construction of a conventional DCT, the first driving shaft  11  is provided with odd number-speed transmission driving gears  21  in order to provide odd number speeds, and the second driving shaft  15  is provided with even number-speed transmission driving gears  21  in order to provide even number speeds. In addition, a reverse driving gear  35  is provided on the second driving gear  15  in order to drive a reverse driven gear  39  of the output shaft  17  via an idler gear  37 . 
         [0028]    With reference to  FIG. 2 , in various embodiments the hybrid power train may be mounted to a front engine front drive (FF) vehicle, wherein the output shaft  17  is provided with a final reduction gear  41 , which meshes with a front wheel-differential gear  43  so as to drive a front wheel. 
         [0029]    With reference to  FIG. 5 , in various embodiments, the hybrid power train may be mounted to a front engine rear drive (FR) vehicle, wherein a propeller shaft  45  is connected to the output shaft  17 , and a rear wheel-differential gear  47  is connected to the propeller shaft  45 , thereby driving a rear wheel. 
         [0030]    The operation of the illustrated embodiment shown in  FIG. 5  will be described with reference to  FIGS. 6 to 8 . 
         [0031]      FIG. 6  shows the state in which a first-stage speed is accomplished with the driving force from the engine  27 , while the electric motor  25  is not driven. 
         [0032]    That is, power from the engine  27  drives the driving gear  1  of the input shaft  3  via the main clutch  31 . Power from the driving gear  1  is concurrently supplied to the first and second driven gears  5  and  7 . The rotation force of the first driven gear  5  rotates the first driving shaft  11  following the action of the first clutch  9 . In the state in which the synchronizing device  23  enabled the first-stage speed transmission driving gear  21  to synchronously mesh with the first driving shaft  11 , power from the first driving gear  11  rotates the output shaft  17  via the first-stage speed transmission driving gear  21  and transmission driven gear  19 , thereby outputting the first-stage power via the output shaft  17 . 
         [0033]      FIG. 7  shows the case where in the driven state shown in  FIG. 6 , power generated by the electric motor  25  is additionally applied. Here, the operation of  FIG. 7  is the same as that of  FIG. 6 , except for the following operation. Since the driving force of the electric motor  25  is also provided to the driving gear  1 , the power from the electric motor  25  is combined with the power from the engine  27 , and the combined power is speed-changed to a first-stage speed and is output from the output shaft  17 . Here, such a running mode means a hybrid running mode which can be used upon acceleration or when the vehicle is ascending. 
         [0034]      FIG. 8  shows the state in which the main clutch  31  is decoupled to stop the operation of the engine  27  in the driven state shown in  FIG. 7 , wherein the first-stage speed change is obtained by only power from the electric motor  25  so as to drive the output shaft  17 . In this state, the vehicle is driven in a completely electric running mode. 
         [0035]    Speed change or power flow to other transmission stages is the same as in a manual transmission or DCT, so description thereof will be omitted. 
         [0036]    In the meantime,  FIG. 9  shows a four-wheel drive using a power train according to various embodiments of the present invention, wherein a front wheel-differential gear  43  and a propeller shaft  45  are connected to an output shaft  17 , and a rear wheel-differential gear  47  is connected to the propeller shaft  45 , so that the front wheels and the rear wheels are all driven. 
         [0037]    For convenience in explanation and accurate definition in the appended claims, the terms front or rear, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
         [0038]    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.