Abstract:
A transmission and components thereof that consists of three forward speed ratios for an electric vehicle market is brought forth. The transmission has an input shaft for receiving torsional energy from an electric motor. A counter shaft is provided which is powered from the input shaft. A first normally closed clutch is provided for powering the first and third gears. A second normally open clutch is provided for powering the second gear. A synchronizer rotatably is provided for selectively torsionally connecting the first of third gears.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/276,866, filed Sep. 17, 2009 and U.S. Provisional Application No. 61/337,221, filed Feb. 1, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a transmission and component thereof that consists of three forward speed ratios for an electric vehicle market. 
       BACKGROUND OF THE INVENTION 
       [0003]    Dual clutch transmissions have been provided to give a vehicle the ease of operation typically associated with vehicles having an automatic transmission while at the same time providing the operational efficiencies most often associated with vehicles having a manually operated transmission. It is desirable to bring the advantages associated with dual clutch transmissions to electrically powered vehicles. Additionally, it is desirable to provide a dual clutch transmission which minimizes parasitic losses associated with fluid activated clutches provided for a typical dual clutch transmission. 
       SUMMARY OF THE INVENTION 
       [0004]    To make manifest the above noted and other manifold desires, a revelation of the present invention is brought forth. In a preferred embodiment, the present invention brings forth a dual clutch automotive vehicle transmission and component thereof. The transmission has an input shaft for receiving torsional energy from an electric motor. A counter shaft is provided which is powered from the input shaft. A first normally closed clutch is provided for powering the first and third gears. A second normally open clutch is provided for powering the second gear. A synchronizer is provided for selectively torsionally connecting the first or third gear with a shaft torsionally associated with an output shaft. 
         [0005]    Other advantages of the present invention will be readily apparent to those skilled in the art as the invention is further revealed from the accompanying drawings and detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a schematic view of a dual clutch transmission of the present invention for an electric motor powered automotive vehicle; 
           [0008]      FIG. 2  is a cross-sectional view of the transmission shown in  FIG. 1 ; 
           [0009]      FIG. 3  is an alternate preferred embodiment dual clutch transmission of the present invention; 
           [0010]      FIG. 4  is another alternate preferred embodiment dual clutch transmission according to the present invention; 
           [0011]      FIG. 5  is still yet another alternative preferred embodiment dual clutch transmission according to the present invention; 
           [0012]      FIG. 6  is another alternate preferred embodiment dual clutch transmission according to the present invention; 
           [0013]      FIG. 7  is another alternate preferred embodiment dual clutch transmission according to the present invention similar to that shown in  FIG. 6 , however, being for a rear wheel drive arrangement; 
           [0014]      FIG. 8  is another alternate preferred embodiment dual clutch transmission according to the present invention for a rear wheel drive vehicle; 
           [0015]      FIG. 9  is another alternate preferred embodiment dual clutch transmission according to the present invention for a rear wheel drive vehicle; 
           [0016]      FIG. 10  is another alternate preferred embodiment dual clutch transmission according to the present invention for a rear wheel drive vehicle; 
           [0017]      FIG. 11  is another alternate preferred embodiment dual clutch transmission according to the present invention for a rear wheel drive vehicle; 
           [0018]      FIG. 12  is a front perspective view of a clutch housing for a clutch utilized in the dual clutch transmission shown in  FIG. 11 ; 
           [0019]      FIG. 13  is a rear perspective view of the dutch housing shown in  FIG. 12 ; 
           [0020]      FIG. 14  is a front elevational view of the clutch housing shown in  FIG. 12 ; 
           [0021]      FIG. 15  is a side elevational view of the clutch housing shown in 
           [0022]      FIG. 11 ; 
           [0023]      FIG. 16  is a sectional view of the clutch housing shown in  FIGS. 12 and 17  taken along lines  16 - 16 ; 
           [0024]      FIG. 17  is a rear elevational view of the clutch housing shown in  FIG. 11 ; 
           [0025]      FIG. 18  is a view taken along line  18 - 18  of  FIG. 17 ; and 
           [0026]      FIG. 19  is a view taken along lines  19 - 19  of  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0028]    Referring to  FIGS. 1 and 2 , a dual clutch transmission  7  for an electrically powered vehicle is provided. Transmission  7  has an input shaft  10 . The input shaft  10  rotates along an axis  12 . The axis  12  is coterminous with the output axis of an electric motor  14  which powers the vehicle. Rotatably mounted on the input shaft  10  by a needle bearing  16  is an outer shaft  18 . The outer shaft  18  has integrally formed therewith a first input gear  20  and a third input gear  22 . Torsionally connected to the outer shaft  18  at its extreme end is a first/third gear clutch housing  24  which mounts a first friction pack  26 . The first friction pack  26  has alternating friction discs  27  and separator plates  29 . The separator plates  29  along their outer diameter are spline connected to the clutch housing  24 . The friction discs  27  along their inner diameter are spline to a clutch hub  28 . The first input gear  20  meshes with a first output gear  30 . The third input gear  22  meshes with a third output gear  32 . The output gears  30  and  32  are mounted by needle bearings on an output shaft  34 . To torsionally connect the output shaft  34  with the remainder of the drive train of the vehicle, the output shaft  34  has an integral pinion output gear  36  that meshes with a differential input gear  38 . Gear  38  is a ring gear which drives differential shaft output gears  40  and  42  which drives left and right and front drive shafts and wheels (not shown) of the vehicle or could also be used to drive the front and rear axle when installed in a longitudinal in an all-wheel drive configuration. (Note in  FIG. 2 , the input shaft, output shaft and differential are shown in a common plane for purposes of illustration only; in many applications, their axes are in different planes). 
         [0029]    The input shaft  10  also has an integrally formed second input gear  44 . The second input gear  44  meshes with a second output gear  46 . The second output gear  46  is rotatably mounted on the output shaft  34  and can be torsionally connected with the output shaft  34  via a second gear clutch housing  48  which interacts with a friction pack  50  and an inner hub  52  which upon activation of the friction pack  50  torsionally connects the second output gear  46  with the output shaft  34 . The friction pack  50  is on an extreme end of the output shaft opposite of friction pack  26 . 
         [0030]    A first third gear synchronizer  54  is provided for selectively connecting the first output gear  30  or the third output gear  32  with the output shaft  34 . 
         [0031]    The first third gear clutch which includes clutch housing  24 , friction pack  26  and hub  28 , has a spring member  60  which causes the friction pack  26  to be normally engaged (closed) thereby causing the outer shaft  18  to be torsionally connected with the input shaft  10  during normal stages of operation. A hydraulically powered actuator  63  upon activation causes the friction pack  26  to be released thereby opening the normally closed friction patch  26 . In an opposite manner, the clutch for the second gear which includes clutch housing  48 , friction pack  50  and hub  52  is biased to a normally open position unless acted upon by actuator  66  to engage the second friction pack  50  to connect the second output gear  46  with the output shaft  34 . Releasing actuator  63 , the friction pack  26  disconnects the outer shaft  18  from the input shaft  10 . Thereafter or simultaneously the actuator  66  is actuated to engage the friction pack  50  to torsionally connect the second output gear  46  with the output shaft  34 . Thereafter, torsional force flows from the input shaft  10  through second input gear  44  through second output gear  46  to the output shaft  34  and through the output gear  36  to the differential. To provide a parking brake function, all that is needed is the actuation of the second dutch friction pack  50  while the first dutch is left in its normally dosed state. 
         [0032]    Referring to  FIG. 3 , an alternate preferred embodiment electric vehicle dual dutch transmission  107  is provided. Transmission  107  is powered by motor  102  powering a motor output shaft  103 . Motorized output shaft  103  is torsionally connected with a gear  104 . Gear  104  is in mesh with an input gear  105 . Input gear  105  is torsionally connected with a double clutch housing  106 . Double clutch housing  106  includes a normally closed first and third gear dry clutch  108  and a second normally open second gear clutch  110 . The second gear clutch  110  when closed torsionally connects a second input gear  112  with an input shaft  114 . The first and third gear clutch  108  connects a first input gear  116  and a third input gear  118  with the input shaft  114 . The first input gear  116  and third input gear  118  mesh with first output gear  120  and third output gear  122  respectively. First output gear  120  or third output gear  122  are selectively torsionally connected with an output shaft  124  by the first third gear synchronizer  126 . The second input gear  112  is meshed with the second output gear  128  that is torsionally affixed with the output shaft  124 . The output shaft  124  has a pinion output gear  132  which is then meshed with the ring input gear  136  of the differential  138 . As the same as with transmission  7 , previously described, the first third gear clutch  108  is normally closed and the second gear clutch  110  is normally open. The transmission shifting logic for transmissions  107  is essentially identical to that previously described for transmission  7 . An advantage of the transmission  107  over transmission  7  is that 1 st /3 rd  clutch  108  of transmission  107  spins at a slower speed than in transmission  7  (friction pack  26 ). This may enable the use of a wet clutch instead of the dry clutch cited for friction pack  26 . 
         [0033]    Referring to  FIG. 4 , an alternate preferred embodiment transmission  207  according to the present invention is provided. Dual clutch transmission  207  has an input shaft  210  that is axially coterminous with the output shaft  212  of a motor  214  powering the transmission. The input shaft  210  empowers a dual clutch housing  220  for a dry second gear normally open clutch  222  and a dry first and third gear normally closed clutch  224 . A third input gear  226  meshes with a third output gear  228 . A first input gear  230  meshes with a first output gear  232 . A second input gear  234  meshes with a second output gear  236  which is torsionally fixably connected with an output shaft  240 . The output shaft  240  is torsionally fixably connected with an output gear  242  which meshes with a differential ring input gear  244  for a differential  246 . A first and third gear synchronizer  250  is provided to selectively connect first output gear  232  or third output gear  228  with the output shaft  240 . The operation transmission  207  is essentially identical to those previously described transmissions  107  and  7 . An advantage of transmission  207  over transmission  7  is that transmission  207 &#39;s primary axial length is a more compact package than that of transmission  7 . In transmission  207 , the first, second and third gears are all on a common side of the combined first and second clutch housings  220 . 
         [0034]    Referring to  FIG. 5 , a dual clutch transmission embodiment  307  is provided having a motor  302  with an output shaft  304  having an axis coterminous with an input shaft  310  of transmission. Transmission  307  has a normally engaged first and third gear clutch  312  and a normally open second gear clutch  314  which share common clutch housing  313 . First third gear clutch  312  drives a first input gear  320  and a third input gear  322 . Second clutch  314  drives a second input gear  324 . First input gear  320  meshes with first output gear  326 . Third input gear  322  meshes with third output gear  328 . A first third synchronizer  330  selectively connects the first output gear  326  or third output gear  328  with an output shaft  332 . A second output gear  334  meshes with the second input gear  324 . An output gear drive pinion  338  meshes with a differential ring input gear  340  which in turn drives a differential  342 . The selection sequence for the operation of the clutches and the synchronizer for the transmission  307  are the same as those previously described for transmission  7 ,  107  and  207 . An advantage of transmission  307  over transmission  7  is that transmission  307  has a shorter axial length. 
         [0035]    Referring to  FIG. 6 , a dual clutch transmission embodiment  407  is provided having a motor  402  with an output shaft  404  having an axis coterminous with an axis of an input shaft  410  of a dual clutch of the transmission. Transmission  407  has a normally engaged first and third gear clutch  412  and a normally open second gear clutch  414  which share common clutch housing  413 . A first third gear synchronizer  420  is utilized to selectively connect a first input gear  422  or third input gear  424  to a transmission inner input shaft  426 . The normally open second gear dutch  414  can selectively engage a transmission outer input shaft  428  to rotate a second input gear  430 . A counter shaft output shaft  432  has torsionally connected therewith a second output gear  434 , a third output gear  436  and a first output gear  438  which mesh with their respective input gears. An output pinion  440  provides a torsional connection of an input ring gear  442  of a differential  444 . The selection sequence for the operation of the clutches and the synchronizer with the transmission  407  is the same of those previously described in transmission  7 . Transmission  407  allows the synchronizer for the first and third gears to be placed on a shaft coterminous with the axis of the motor output shaft  404 . Placing the synchronizer on the same axis as the input shaft allows the synchronizer to have a lower torsional capacity and thus less cost. 
         [0036]    Transmission  507  provides an arrangement essentially identical to transmission  407  with the exception that transmission  507  does not have a pinion gear  440 , but provides an output to a prop shaft (not shown) which is directly connected to the output or counter shaft  432  allowing the transmission  507  to utilize for rear wheel drive vehicles. 
         [0037]    Referring to  FIG. 8 , a dual clutch transmission  607  for an electrically powered vehicle is provided. The transmission is for a vehicle with a parallel mounted motor (not shown). Typically, such vehicles are front end motor rear wheel drive vehicles. Transmission  607  has an input shaft  610 . The input shaft  610  rotates along an axis  612 . The axis  612  is coterminous with the output axis of an electric motor (not shown) which powers the vehicle. Rotatably mounted on the input shaft  610  by needle bearings  616  is an outer shaft  618 . The outer shaft  618  has integrally formed therewith a first input gear  620  and a third input gear  622 . Torsionally connected to the outer shaft  618  at its extreme end is a first/third gear clutch housing  624  which mounts a first dry friction pack  626 . The first friction pack  626  has alternating friction discs  627  and separator plates  629 . The separator plates  629  along their outer diameter are spline connected to the clutch housing  624 . The friction discs  627  along their inner diameter are spline to a clutch hub  628 . The first input gear  620  meshes with a first output gear  630 . The third input gear  622  meshes with a third output gear  632 . The output gears  630  and  632  are mounted by needle bearings on an output shaft  634 . To torsionally connect the output shaft  634  with a remainder of the drive train of the vehicle (rear differential), the output shaft  634  has an output hub  636  that connects with a prop shaft (not shown). (Note in  FIG. 8 , the input shaft  610  and output shaft  634  are shown in a common horizontal plane for purposes of illustration only; in many applications, their axes vary in elevation). 
         [0038]    The input shaft  610  also has an integrally formed second input gear  644 . The second input gear  644  meshes with a second output gear  646 . The second output gear  646  is rotatably mounted on the output shaft  634  and can be torsionally connected with the output shaft  634  via a second gear clutch housing  648  which interacts with a dry friction pack  650  and an inner hub  652  which upon activation of the friction pack  650  torsionally connects the second output gear  646  with the output shaft  634 . The friction pack  650  is on an extreme end of the output shaft opposite of friction pack  626 . 
         [0039]    A first third gear synchronizer  654  is provided for selectively connecting the first output gear  630  or the third output gear  632  with the output shaft  634 . 
         [0040]    The first third gear clutch which includes clutch housing  624 , friction pack  626  and hub  628 , has a spring member  660  which causes the friction pack  626  to be normally engaged (closed) thereby causing the outer shaft  618  to be torsionally connected with the input shaft  610  during normal stages of operation. A hydraulically powered actuator  663  upon activation causes the friction pack  626  to be released thereby opening the normally closed friction pack  626 . In an opposite manner, the clutch for the second gear which includes clutch housing  648 , friction pack  650  and hub  652  is biased to a normally open position unless acted upon by actuator  666  to engage the second friction pack  650  to connect the second output gear  646  with the output shaft  634 . To shift second gear from first or third gear actuator  663  releases friction pack  626  to disconnect the outer shaft  618  from the input shaft  610 . Thereafter or simultaneously the actuator  666  is actuated to engage the friction pack  650  to torsionally connect the second output gear  646  with the output shaft  634 . Thereafter, torsional force flows from the input shaft  610  through second input gear  644  through second output gear  646  to the output shaft  634  and hub  636 . To provide a parking brake function, all that is needed is the actuation of the second dutch friction pack  650  while the first clutch is left in its normally closed state. 
         [0041]    Referring to  FIG. 9 , a rear wheel drive transmission  702  for a three speed electric vehicle is provided which has an input shaft  1000  which powers a dual clutch  1002 . The function of clutch  1002  will be described in greater detail later. Dual clutch  1002  selectively powers an outer input shaft  704  which is in turn connected with second input gear  702 . Dual clutch  1002  also powers an inner input shaft  706  which is integrally connected with a third input gear  708  and a first input gear  710 . Transmission  702  also has a counter or output shaft  712  which has torsionally connected thereto a parking brake gear  714 . Output shaft  712  has a fixably connected second output gear  716 . A first third gear synchronizer  718  is provided to selectively connect with the output gear  712 , a first output gear  720 , or a third output gear  722 . Output shaft  712  is connected with a prop shaft (not shown) which is in turn connected with the rear wheel drive differential (not shown). Transmission  707  allows the inner and outer input shaft clutches to share a common housing. 
         [0042]    Transmission  807  is a dual clutch rear wheel transmission for an electric vehicle. Transmission  807  has a dual clutch  1003  essentially similar in design and function to that of dual clutch  1002  previously mentioned. Transmission  807  has a first inner input shaft  806  which powers a first input gear  810  and a third input gear  808 . An outer input shaft  804  powers a second input gear  802 . A counter shaft  812  is provided. Counter shaft  812  is fixably connected with second output gear  816 . A first third synchronizer  818  selectively connects first output gear  820  or third output gear  822  with counter shaft  812 . Fixably connected towards a rearward end of the counter shaft  812  is an output gear  830 . Output gear  830  is meshed with a second output gear  832  which has the same rotational axis as the inner input shaft  806  and outer input shaft  804 . Second output gear  832  is integral with an output shaft  834  which is in turn torsionally connected with a prop shaft going to a rear differential of the vehicle. Transmission  807  is advantageous in that its output is axially aligned with the input to its dual dutch  1003 . 
         [0043]    Referring to  FIG. 11 , transmission  907  is provided. Transmission  907  has a dual dutch  1003  that selectively powers an outer input shaft  908  or an inner input shaft  910 . Outer input shaft  908  is integrally connected with a second input gear  912  which is in turn meshed with a second output gear  914  which is integrally formed by a counter shaft  916 . Transmission  907  also has a first input gear  918  which is meshed with a third output gear  920 . Gear  920  is torsionally affixed to shaft  916 . An output gear  922  is affixed to the end of shaft  916 . Gear  922  is meshed with gear  924  which is fixably connected with output shaft  926 . A first third gear synchronizer  928  selectively connects gear  918  with the inner input shaft  910  or connects output gear  924  with the inner input shaft  910 . Accordingly, when second gear is desired, clutch  103  will be released from input shaft  910  and will be connected with the outer input shaft  908  allowing gear  912  to mesh with gear  914  causing gear  922  to mesh with gear  924  which in turn is connected with output shaft  926 . For first gear ratio operation, clutch  1003  will actuate the inner input shaft  910  and will be released from the outer input shaft  908 . Synchronizer  928  connects gear  918 , directing torque to gears  922  and  924 . For third gear operation synchronizer  928  connects gear  924  and shaft  926  for direct connection or direct drive to input shaft  910  allowing direct drive operation for third gear. Transmission  907  is also advantageous with respect to transmission  807  in that a gear set is eliminated while still retaining an output that is axially aligned with the input shaft of the transmission. 
         [0044]      FIGS. 12  thru  19  provide enlarged views of the dual clutch  1003  shown in  FIG. 11 . Dual clutch  1003  has certain features which optimize its use in a dual clutch transmission for an electric vehicle. Clutch  1003  has an aluminum casing to save weight including a front housing  1020  and a rear housing  1022 . The front housing  1020  and rear housing  1022  are connected together by a series of geometrically spaced bolts  1024 . To save weight and energy, the front housing  1020  and rear housing  1022  are typically fabricated from cast aluminum. The front housing  1020  has a neck  1026 . The neck  1026  has an inner diameter  1028 . The clutch has a male input shaft  1032  (see  FIG. 11 ). The male input shaft  1032  is typically fabricated from steel and along its outer diameter  1034  has a series of metal serrations. These metal serrations are pressed into the inner diameter  1028  of the neck  1026  and form corresponding female serrations in the neck inner diameter  1028 . Clutch  1003  has a first clutch which includes hubs  1040  and  1042  for connection on input shaft  910 . As mentioned previously, input shaft  910  is the input shaft for the first and third gears. Hub  1040  is operatively associated with friction disc  1044  and hub  1042  is operatively associated with friction disc  1046 . The hubs  1040  and  1042  are typically fabricated from steel. On a forward side friction disc  1044  is a pressure plate  1048 . Between the friction disc  1044  and  1046  is another pressure plate  1050 . Rearward of the friction disc  1046  is a central pressure plate  1055 . To engage the friction disc  1044  and  1046  with the pressure plates  1048 ,  1050  and  1052 , there is provided a diaphragm  1054 . The diaphragm  1054  adjacent its outer periphery pivots about a fulcrum  1070  which is held in position by a bolt  1072 . The diaphragm  1054  is normally engaging with the pressure plate  1048  to apply the clutch for the inner diameter input shaft  910 . To release the clutch for the inner diameter, a series of push rods  1056  which are controlled by a stationary piston  1060  (see  FIG. 11 ) contact the diaphragm along the inner portion of the diaphragm urging the diaphragm outer end  1062  forwardly to relieve or disengage the clutch. Pressure plate  1048  and  1050  have lugs  1064  and  1066  respectively which abut a bridge  1068  of the clutch front housing to ensure that the pressure plates rotate with the housing. The central pressure plate  1052  is penetrated by the bolt  1024  to ensure its rotation with the front and rear housing  1020  and  1022  of the clutch. 
         [0045]    The generally open clutch for the transmission outer input shaft  908  ( FIG. 11 ) includes a hub  1074 . Hub  1074  mounts friction disc  1076  which is axially fixed thereto. Additionally, hub  1074  mounts friction disc  1080 . Friction disc  1080  has limited axial movement with respect to hub  1074 . Between the friction disc  1076  and  1080  is a pressure plate  1082  which has a lug  1084  which abuts a bridge  1086  of the rear housing. The outer diameter shaft clutch also has a backing plate  1087  with lugs  1088  which also abut the bridge  1086  to keep the pressure plate  1087  from rotating. The rear casing  1022  mounts a rear diaphragm  1091 . In normal operation, the dutch for the outer shaft is not engaged. When it is desired to engage the outer shaft dutch, a piston  1092  ( FIG. 11 ) is actuated against one of the fingers  1093  of the diaphragm pushing against pressure plate  0187  to capture friction disc  1080 , pressure plate  1082  and friction disc  1076  with the central pressure plate  1052  to thereby transfer torsional energy from the dutch to the outer input shaft  912 . To release the dutch for the outer input shaft  912 , the piston  1092  is deactivated. To minimize any drag which the clutch for the outer input shaft can cause during operation (which is critical for an electrically driven engine), a post  1094  is provided. The post has encircling between it and the central pressure plate  1052  a coil spring  1095 . A head of the post  1094  in combination with the spring  1095  provides a stop to ensure that the pressure plate  1087  is pushed back to a minimum distance from the central pressure plate  1052  to minimize any potential drag that can occur when the hub  1074  is rotating and wherein it is desired that the clutch for the outer input shaft not be engaged. The axial floating nature of friction disc  1080  upon the hub  1074  also helps to contribute to a minimum of drag forces being induced. The dutch  1003  also has a headed post  1098  which penetrates the pressure plate  1082  and captures between the pressure plate spring washers  1099 . Spring washers  1099  perform a function similar to that previously described for spring  1095  to ensure that pressure plate  1082  comes to a minimum distance away from central pressure plate  1052  to minimize any possible drag of the pressure plate  1082  with friction disc  1076  or friction disc  1080 . 
         [0046]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.