Abstract:
In a double clutch transmission, the number of components of the transmission may be reduced and the gear train optimally arranged with a plurality of gears for two clutches and six-stage gear ratios. Such an arrangement proves for smooth shifting of gears to the range R and compacting of the structure of the transmission to facilitate positioning and assembly of the transmission in the vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is based on, and claims priority from, Korean Application Serial Number 10-2004-0063803, filed on Aug. 13, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a double clutch transmission adapted to reduce the number of components required in the transmission and to optimally arrange the gear train, thereby improving the loading of the transmission in the vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     A double clutch transmission selectively receives engine power through two clutches, enabling to embody an automatized transmission without a driver&#39;s manual manipulation of the gear shift.  
         [0004]     The double clutch transmission typically has at least six-stage gear ratios; however, a plurality of gears for two clutches and six-stage gear ratios causes the size of the transmission to increase, thus making the transmission difficult to be mounted in the vehicle.  
       SUMMARY OF THE INVENTION  
       [0005]     Embodiments of the present invention are provided to decrease the number of utilized components in the transmission and to optimize the arrangement of the gear train with a plurality of gears for two clutches and six-stage gear ratios, thereby compacting the structure of a double clutch transmission and consequently improving the loading of the transmission in the vehicle.  
         [0006]     A double clutch transmission according to one embodiment includes a first input shaft directly connected to a first clutch. A second input shaft is directly connected to a second clutch and has a rotation shaft identical to that of the first input shaft. A first speed drive gear, third speed drive gear and fifth speed drive gear are installed at the first input shaft. A second speed drive gear and fourth-sixth speed drive gear are installed at the second input shaft. A first output shaft is installed with a first output gear and a plurality of speed driven gears that meshes with the speed drive gears of the first input shaft and second input shaft. A second output shaft is installed with a second output gear and a plurality of speed driven gears that meshes with the speed drive gears of the first input shaft and second input shaft. A differential includes a ring gear engaged with the first output gear and second output gear. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which:  
         [0008]      FIG. 1  is a schematic view of the structure of a double clutch transmission according to an embodiment of the present invention; and  
         [0009]      FIG. 2  is an arrangement plan of shafts when observed from the left of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]     Referring to  FIG. 1 , a first input shaft  3  according to an embodiment of the present invention is directly connected to a first clutch  1 . A second input shaft  7  is directly connected to a second clutch  5  and has a rotation shaft identical to that of first input shaft  3 . A first speed drive gear  9 , third speed drive gear  11 , and fifth speed drive gear  13  are installed at first input shaft  3 . A second speed drive gear  15  and fourth-sixth speed drive gear  17  are installed at second input shaft  7 . A first output shaft  21  is installed with a first output gear  19  and a plurality of speed driven gears, which meshes with the speed drive gears of first input shaft  3  and second input shaft  7 . A second output shaft  25  is installed with a second output gear  23  and a plurality of speed driven gears, which meshes with the speed drive gears of first input shaft  3  and second input shaft  7 . A differential  29  has a ring gear  27  engaged with first output gear  19  and second output gear  23 .  
         [0011]     First input shaft  3  and second input shaft  7  receive the power of the engine via first clutch  1  and second clutch  5 . Second input shaft  7  encloses the circumference of first input shaft  3  as illustrated in the drawing.  
         [0012]     Hereinafter, for the purposes of clarity of description only, the left of  FIG. 1  designates the rear of the transmission and the right thereof designates the front of the transmission.  
         [0013]     The rear end of first input shaft  3  is supported by a first input shaft main bearing  31 . First speed drive gear  9  is disposed on first input shaft  3  and closely located to first input shaft main bearing  31 . Third speed drive gear  11  is installed on first input shaft  3  in front of first speed drive gear  9 . Fifth speed drive gear  13  is also positioned on first input shaft  3  in front of third speed drive gear  11 .  
         [0014]     First input shaft  3  is installed in order with the first, third, and fifth speed drive gears from the rear toward the front of the vehicle. First input shaft main bearing  31  is located near first speed drive gear  9  to properly support a high load of first speed drive gear  9 .  
         [0015]     Corresponding to the arrangement of the gears of first input shaft  3 , first output shaft  21  is equipped with a first speed driven gear  33 , third speed driven gear  35 . First speed driven gear  33  engages with first speed drive gear  9 , and third speed driven gear  35  engages with third speed drive gear  11 . A first-third synchronizer  37  is interposed between first speed driven gear  33  and third speed driven gear  35 .  
         [0016]     When first-third synchronizer  37  operates, first output shaft  21  receives power from any one of first speed drive gear  9  or third speed drive gear  11  of first input shaft  3 , and the power is transmitted to the wheels through differential  29 . The first or third speed of the transmission can be embodied in the above state.  
         [0017]     Second input shaft  7  is installed with fourth-sixth speed drive gear  17  in front of fifth speed drive gear  13 . Second speed drive gear  15  is installed on second input shaft  7  in front of fourth-sixth speed drive gear  17 . A second input shaft main bearing  39  is placed between second speed drive gear  15  and second clutch  5 .  
         [0018]     Second input shaft main bearing  39  is installed in close proximity to second speed drive gear  15 , thus allowing a high load of second speed drive gear  15  to be properly supported.  
         [0019]     First output shaft  21  is installed with a second speed driven gear  41 , fourth speed driven gear  43 , and second-fourth synchronizer  45 . Second speed driven gear  41  engages with second speed drive gear  15 , and fourth speed driven gear  43  engages with fourth-sixth speed drive gear  17 . Second-fourth synchronizer  45  is interposed between second speed driven gear  41  and fourth speed driven gear  43 .  
         [0020]     When second-fourth synchronizer  45  operates, first output shaft  21  receives power from any one of second speed drive gear  15  or fourth-sixth speed drive gear  17  of second input shaft  7 , and the power is transmitted to the wheels through differential  29 . The second or fourth speed of the transmission can be embodied in the above state.  
         [0021]     A parking gear  47  is equipped between third speed driven gear  35  and fourth speed driven gear  43  of first output shaft  21 . A spacer may be located at the position of parking gear  47 . However, in one embodiment of the present invention, parking gear  47  functions as the spacer, which retains the interval of third speed driven gear  35  and fourth speed driven gear  43 , thereby reducing the number of components and weight of the transmission.  
         [0022]     The rear end of first output shaft  21  is supported by a first output shaft rear main bearing  49 . First output gear  19  is equipped in front of second speed driven gear  41 , and a first output shaft front main bearing  51  that supports first output shaft  21  is equipped in front of first output gear  19 .  
         [0023]     Thus, the high load applied on first speed driven gear  33  is properly supported via first output shaft rear main bearing  49  adjacently located to first speed driven gear  33 . The high load on second speed driven gear  41  is properly supported via first output shaft front main bearing  51  adjacently located to second speed driven gear  41 .  
         [0024]     Second output shaft  25  is equipped with a fifth speed driven gear  53  and fifth synchronizer  55 . Fifth speed driven gear  53  engages with fifth speed drive gear  13 , and fifth synchronizer  55  converts the power transmission state between fifth speed driven gear  53  and second output shaft  25 .  
         [0025]     The fifth speed state can be performed by manipulating fifth synchronizer  55  to operate differential  29  by sequentially transmitting power from first input shaft  3  to fifth speed drive gear  13 , fifth speed driven gear  53 , second output shaft  25  and second output gear  23 .  
         [0026]     Second output shaft  25  is equipped with a sixth speed driven gear  59  that engages with fourth-sixth speed drive gear  17 . A reverse (R) driven gear  61  is also installed on second output shaft  25 . A sixth-R synchronizer  63  is positioned between sixth speed driven gear  59  and reverse driven gear  61 .  
         [0027]     A reverse idle driven gear  65  meshes with second speed drive gear  15  and is installed on a reverse idle shaft  67 . A reverse idle drive gear  69  is installed on reverse idle shaft  67  and meshes with reverse driven gear  61 .  
         [0028]     During the operation of sixth-R synchronizer  63 , the sixth speed or reverse state can be performed. If the transmission is in the sixth speed state, the power from second input shaft  7  is sequentially transmitted to differential  29  through fourth-sixth speed drive gear  17 , sixth speed driven gear  59 , second output shaft  25 , and second output gear  23 .  
         [0029]     In case of the reverse state, the power from second input shaft  7  is transmitted to differential  29  successively through second speed drive gear  15 , reverse idle driven gear  65 , reverse idle shaft  67 , reverse idle drive gear  69 , reverse driven gear  61 , second output shaft  25 , and second output gear  23 .  
         [0030]     The rotation of reverse driven gear  61  is in a reverse direction to that of second speed drive gear  15  via reverse idle driven gear  65 , reverse idle shaft  67  and reverse idle drive gear  69 , thus allowing the rear shift to be performed.  
         [0031]     Reverse idle driven gear  65  operates via second speed drive gear  15  in the embodiment of the present invention without a supplementary gear, thus decreasing the number of components and weight of the transmission.  
         [0032]     The interval between reverse idle driven gear  65  and reverse idle drive gear  69  is smaller than that between second speed drive gear  15  and fourth-sixth speed drive gear  17 .  
         [0033]     The reverse idle shaft  67  mounted with reverse idle driven gear  65  and reverse idle drive gear  69  can be formed with a short length, resulting in a reduction of the transmission weight. Further, during the shift to the range R, a smooth gearshift can be executed by reducing the inertia of reverse idle shaft  67 .  
         [0034]     Second output shaft  25  is mounted with fifth synchronizer  55  at the rear of fifth speed driven gear  53 . A second output shaft rear main bearing  71  supporting second output shaft  25  is mounted at the rear of fifth synchronizer  55 . Second output gear  23  is installed in front of reverse driven gear  61 . A second output shaft front main bearing  73  is placed in front of second output gear  23 . This allows second output shaft  25  to firmly be supported at the transmission case.  
         [0035]     As apparent from the foregoing, there is an advantage in that although a plurality of gears for two clutches and six-stage gear ratios are included in the embodiment of the present invention, the number of transmission components is reduced and the gear train is optimally arranged, contributing to a smooth gearshift to the range R and an improvement of the loading of the transmission in the vehicle by compacting the structure thereof.