Abstract:
A multi-speed transmission for transmitting power from a power source includes a torque converter as well as dual clutches which may be arranged as dual input clutches or dual output clutches. To combine the smoothness and ratio boosting effects of a torque converter with the low spin loses associated with synchronizers used in dual clutch designs. The torque converter and dual clutches as well as synchronizers and a plurality of intermeshing gears are utilized to transfer torque from an input member to an output member at a plurality of speed ratios.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/571,761, filed May 17, 2004, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to a multi-speed, dual clutch transmission connectable with a torque converter. 
     BACKGROUND OF THE INVENTION 
     Dual input clutch transmissions have been designed with friction launch clutches to connect a vehicle engine to selectively engaged gears in a lay shaft transmission. Dual input clutch transmissions are designed to permit engine power to be distributed through power paths that are dependent upon which input clutch is engaged. Dual input clutch power transmissions are typically designed as countershaft-type transmissions (i.e., lay shaft transmissions) wherein engagement of a first of the input clutches creates a power path from an input shaft through a first countershaft to an output shaft, and engagement of a second of the input clutches creates a power path through a second countershaft to the output shaft. Synchronizers engage gears with the countershafts to complete the powerflow to the output shaft. Layshaft designs and other transmission configurations that use synchronizers for selectively engaging gears with a shaft provide relatively low spin losses, thus enhancing overall operating efficiency. 
     The art has also employed the clutch of a planetary transmission as a friction launch mechanism that provides launch slip in connecting a set of interconnected planetary gear sets with an input shaft connected to an engine to transfer power from the input shaft to an output shaft. One such power transmission with a friction launch torque-transmitting mechanism is disclosed in commonly-assigned U.S. Pat. No. 6,471,616, issued to Paul D. Stevenson on Oct. 29, 2002, which is hereby incorporated by reference in its entirety. 
     Furthermore, the art has also employed a torque converter connectable with planetary or layshaft gear sets in a transmission to transfer power from a power source, such as an engine, to an output shaft. The torque converter provides a torque multiplier and speed differential between the engine and the gearing. The fluid coupling function of the torque converter enables a smooth transmission of power during launch, shifting, as well as coasting. A torque converter clutch may or may not be employed to connect the engine to the transmission (bypassing the torque converter) and thereby improve the overall efficiency of the transmission. An example of a powertrain including an engine, a torque converter and a transmission including three planetary gear sets is described in commonly-assigned U.S. Pat. No. 6,729,993, issued to Norman Kenneth Bucknor et al. on May 4, 2004, which is hereby incorporated by reference in its entirety. 
     SUMMARY OF THE INVENTION 
     By utilizing a torque converter with a dual clutch transmission, the invention combines smoothness and ratio-boosting effects of a torque converter with the low spin losses associated with the synchronizers of the dual clutch designs. With respect to a conventional dual clutch transmission, a damper and two launching clutches are replaced by a torque converter and two shifting clutches. Shifting clutches may be more compact, require less heat sink and require less cooling than launching clutches. They may, therefore, be less expensive and may weigh less than launching clutches, as the torque converter provides some of the heat absorbing capability otherwise required by launching clutches. It should be noted that a damper is employed within the torque converter, but such a damper may be smaller than a damper required to be used in conjunction with friction launch clutches, as the inertia of the torque converter itself provides a portion of the required inertia capability. 
     A powertrain having a torque converter and a dual shifting clutch design may be especially advantageous for a vehicle having a low power to weight ratio, as the torque converter provides greater heat sink capability than conventional friction launch clutches. Vehicles having a low ratio of engine speed to vehicle velocity (i.e., a low N/V, where N is the speed of the engine in revolutions per minute (rpm) and V is the velocity of the vehicle in miles per hour (mph)), may be well-suited for a design having a torque converter with dual shifting clutches, due to the heat sink capability and ratio-boosting effect of the torque converter. Additionally, the relatively low spin losses of the synchronizers and wide ratios available in higher gears may improve fuel economy with respect to other powertrain designs. The use of a torque converter with its torque multiplication can allow the use of gear ratios with smaller steps or fewer gear ratios for the same performance. 
     Accordingly, a multi-speed transmission is provided for transmitting power from a power source. The transmission includes an input member and an output member as well as a torque converter operatively connected between the input member and the power source to create a fluid coupling therebetween. The transmission further includes a first shaft and a second shaft as well as a plurality of synchronizers and a plurality of intermeshing gears. One or more of the input member, the output member and the first and second shafts has some of the gears continuously connected thereto for rotation therewith. Others of the gears are selectively interconnectable for rotation with others of the shafts and/or input or output member via selective engagement of the synchronizers. 
     The transmission also includes a first and a second clutch which are alternately selectively engageable for operatively interconnecting the first and second shafts, respectively, with either the input member or the output member. The first and second clutches may be referred to as dual shifting clutches. When the dual shifting clutches are engageable for operatively interconnecting the first shaft and second shaft with the input member, they are referred to as dual input clutches. Likewise, when the first and second clutches are engageable for operatively interconnecting the first and second shaft with the output member, they are referred to as dual output clutches. By selectively engaging the clutches and the synchronizers as described above, the input member is operatively interconnected with the output member through the intermeshing gears to transfer power provided from the power source to the output member. The power source may be a conventional internal combustion engine, but may also be a hybrid engine, diesel engine or other form of power source. 
     In one aspect of the invention, the transmission includes a torque converter clutch which is engageable to establish a mechanical connection between the power source and the input member to bypass the torque converter and effectively establishing a direct one-to-one ratio between the power source and the input member. 
     A variety of different transmission configurations may employ the torque converter and dual shifting clutch combination. For instance, the first and second shaft may be spaced generally parallel to the input member and to the output member in a typical countershaft design. Alternatively, the first and second shafts may be coaxial. Whether of the countershaft or the coaxial design, the alternate engagement of the first and second shifting clutches may operatively interconnect the first and second shaft with the input member or, alternatively, with the output member. The operative interconnection by the first and second clutches of the first and second shaft with either the input member or the output member may be a direct interconnection or an indirect interconnection, i.e., where the interconnection is through some of the intermeshing gears, which in that instance, may be referred to as transfer gears. 
     The input member, output member and first and second countershafts may be physically arranged with respect to one another to establish two axes or three or more axis. For instance, the input member and the output member may be aligned with one another, to establish an axis. Alternatively, the first and second shafts, the input member and the output member may be arranged to establish three or more axis. For instance, in a dual input clutch design, the first and second shafts may be arranged as countershafts spaced apart from one another and parallel to the aligned input and output members, thereby establishing three axes. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a first embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual input clutches; 
         FIG. 2  is a schematic illustration of a second embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual input clutches; 
         FIG. 3  is a schematic illustration of a third embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual input clutches; 
         FIG. 4  is a schematic illustration of a fourth embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual output clutches; 
         FIG. 5  is a schematic illustration of a fifth embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual output clutches; and 
         FIG. 6  is a schematic illustration of a sixth embodiment of a vehicle having a powertrain with an engine, a torque converter and a transmission with dual input clutches. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment: Dual Input Clutch, Counter Shaft Design on Three Axes 
     Referring to the drawings, wherein like reference numbers represent the same or corresponding parts throughout the several views, there is shown in  FIG. 1  a vehicle  10  having a powertrain  12 . The powertrain  12  includes a power source or engine  14 , a torque converter  16  and a transmission  15 . The torque converter  16  is connected with the engine  14  and with the transmission input member  18  via a turbine  22 . Selective engagement of a torque converter clutch  20  allows the engine  14  to be directly connected with the input shaft  18 , bypassing the torque converter  16 . The input member  18  is typically a shaft, and may be referred to as an input shaft herein. Preferably, the torque converter clutch  20  is electronically controlled and may be enhanced with a multitude of clutch plates to provide a large clutch torque capacity, thus making the converter clutch  20  able to transmit a large amount of torque. The torque converter  16  includes the turbine  22 , a pump  24  and a stator  26 . The converter stator  26  is grounded to a casing  30  through a typical one-way clutch that is not shown. A damper  28  is operatively connected to the engaged torque converter clutch  20  for absorbing vibration. 
     An input transfer gear set  32  includes a first transfer gear  34 , a second transfer gear  36 , and third transfer gear  38 . The third transfer gear  38  is continuously interconnected with and rotatable with the input shaft  18 . The first transfer gear  34  intermeshes with the third transfer gear  38 . The first transfer gear  34  is rotatable about a first countershaft  40 . The first transfer gear  34  is selectively engageable with the first countershaft  40  via a first shifting clutch  42 . Similarly, the second transfer gear  36  intermeshes with the third transfer gear  38 . The second transfer gear  36  is rotatable about a second countershaft  44 . The second transfer gear  36  is selectively engageable with the second countershaft  44  via a second shifting clutch  46 . Notably, the first and second shifting clutches  42 ,  46 , respectively, are placed on separate axes (i.e., the first countershaft  40  and the second countershaft  44 , respectively, in the embodiment illustrated in  FIG. 1 ). The transmission  15  establishes three primary axes plus a minor axis I for an idler gear  86 . The input shaft  18  and the output shaft  84  are aligned with one another to establish an axis, as illustrated in  FIG. 1 . The first and second countershafts  40 ,  44  are on two separate axes, parallel to the input and output shafts  18 ,  84 . 
     Within the scope of the invention, the shifting clutches may be connected to the input shaft and may be engageable with concentric first and second shafts for torque transfer from the engine to the first and second shafts as described below with respect to the embodiments of  FIGS. 3 and 6 . However, placing the shifting clutches on the parallel countershafts  40 ,  44 , may afford placement of the clutches in close proximity to the stationary transmission casing (not shown, but generally surrounding the outer periphery of the transmission  15 ), enabling the use of nonrotating shifting pistons to be employed within the shifting clutches. Other shaft configurations may also be employed with a torque converter and dual shifting clutch combination, such as a “delta configuration” (i.e., a triangular configuration having an input member and an output member disposed at one corner of a triangle formed with respect to first and second countershafts disposed at the other two corners). 
     Referring again to  FIG. 1 , the powertrain  12  further includes a first, second, third, fourth, fifth and sixth intermeshing gear  48 ,  50 ,  52 ,  54 ,  56  and  58 , respectively. The first, third and fifth intermeshing gears,  48 ,  52  and  56 , respectively, are each rotatable about and selectively engageable with the first countershaft  40 . Similarly, the second, fourth and sixth intermeshing gears,  50 ,  54  and  58 , respectively, are each rotatable about and selectively engageable with the second countershaft  44 . A seventh/reverse gear  60  is rotatable about and selectively engageable with the second countershaft  44  as well. 
     A first synchronizer  62  is selectively engageable to interconnect the first intermeshing gear  48  with the first countershaft  40 . A second synchronizer  64  is selectively engageable to interconnect the second intermeshing gear  50  with the second countershaft  44  for common rotation therewith. A third synchronizer  66  is selectively engageable to interconnect the third intermeshing gear  52  with the first countershaft  40  for common rotation therewith. A fourth synchronizer  68  is selectively engageable to interconnect the fourth intermeshing gear  54  with the second countershaft  44  for common rotation therewith. A fifth synchronizer  70  is selectively engageable to interconnect the fifth intermeshing gear  56  with the first countershaft  40  for common rotation therewith. A sixth synchronizer  72  is selectively engageable to interconnect the sixth intermeshing gear  58  with the second countershaft  44  for common rotation therewith. A seventh synchronizer  74  is selectively engageable to interconnect the reverse gear  60  with the second countershaft  44  for common rotation therewith. 
     An eighth intermeshing gear  76 , a ninth intermeshing gear  78 , a tenth intermeshing gear  80 , and an eleventh intermeshing gear  82  are each continuously connected to and rotatable with an output member  84 , which in this embodiment is a shaft and may be referred to as an output shaft. The output shaft  84  is connected with a final drive mechanism  85 . The eighth intermeshing gear  76  intermeshes with the first intermeshing gear  48  and with the second intermeshing gear  50 . The ninth intermeshing gear  78  intermeshes with the third intermeshing gear  52  and with the fourth intermeshing gear  54 . The tenth intermeshing gear  80  intermeshes with the fifth intermeshing gear  56  and with the sixth intermeshing gear  58 . The idler gear  86  rotates about an axis I that is generally parallel with the output shaft  84  and with the second countershaft  44 . The idler gear  86  intermeshes with both the reverse gear  60  and with the eleventh intermeshing gear  82 . 
     The transmission  15  is operable for providing six forward speed ratios as well as a reverse speed ratio. Within the scope of the invention, a dual clutch transmission may provide a different number of forward speed ratios, such as five or seven. For instance, a transmission with seven forward speed ratios would require only one more gear interconnectable with the first countershaft  40  via one additional synchronizer. The additional gear would intermesh with the eleventh intermeshing gear  82 . Each of the intermeshing gears is designed with a specific number of teeth to establish desirable torque ratio steps between adjacent torque ratios, as well as to affect the overall speed ratio obtainable with the transmission  15 . (The torque converter  16  also has a ratio-boosting effect that contributes to the overall speed ratio). 
     To establish the reverse speed ratio, the seventh synchronizer  74  is engaged. Additionally, the second shifting clutch  46  is engaged. With the engagement of the second shifting clutch  46  and the seventh synchronizer  74 , torque is transferred from the input shaft  18  to the output shaft  84  in a reverse direction. Torque is transferred from the input shaft  18  to the second countershaft  44  via the intermeshing second transfer gear  36  and third transfer gear  38 . Torque is transferred from the second countershaft  44  to the output shaft  84  via the seventh intermeshing or reverse gear  60 , idler gear  86  and eleventh intermeshing gear  82 . The idler gear  86  reverses the direction of rotation between the seventh/reverse gear  60  and the eleventh intermeshing gear  82 , thereby reversing the direction of rotation between the input shaft  18  and the output shaft  84 . 
     To shift from the reverse speed ratio to the first forward speed ratio, the first synchronizer  62  is preselected (i.e., engaged) prior to shifting from the second shifting clutch  46  to the first shifting clutch  42 . The first shifting clutch  42  is then engaged as the second shifting clutch  46  is disengaged. The seventh synchronizer  74  is then disengaged. 
     In the first forward speed ratio, torque is transferred from the input shaft  18  to the first countershaft  40  via the intermeshing first transfer gear  34  and third transfer gear  38 . Torque is transferred from the first countershaft  40  to the output shaft  84  via the intermeshing first intermeshing gear  48  and eighth intermeshing gear  76 . 
     To shift from the first forward speed ratio to the second forward speed ratio, the second synchronizer  64  is preselected during the first forward speed ratio. The first shifting clutch  42  is then disengaged as the second shifting clutch  46  is engaged. The first synchronizer  62  is then disengaged. With the engagement of the second shifting clutch  46  and the second synchronizer  64 , torque is transferred from the input shaft  18  to the second countershaft  44  via the intermeshing third transfer gear  38  and second transfer gear  36 . Torque is transferred from the second countershaft  44  to the output shaft  84  via the intermeshing second intermeshing gear  50  and eighth intermeshing gear  76  to establish the second forward speed ratio. 
     Because the second shifting clutch  46  is not engaged during the first forward speed ratio, preselection of the second synchronizer  64  does not effect the first forward speed ratio. Preselection of the synchronizer required for the subsequent speed ratio occurs during each previous speed ratio in the transmission  15 . Such preselection allows dynamic shifting to occur. “Dynamic shifting” means that output torque is present during a clutch shift to an oncoming speed ratio. 
     To shift from the second speed ratio to the third speed ratio, the third synchronizer  66  is preselected (i.e., engaged) during the second speed ratio. The second shifting clutch  46  is then disengaged as the first shifting clutch  42  is engaged. The second synchronizer  64  is then disengaged. With the engagement of the first shifting clutch  42  and the third synchronizer  66 , torque is transferred from the input shaft  18  to the first countershaft  40  via the intermeshing first transfer gear  34  and third transfer gear  38 . Torque is transferred from the first countershaft  40  to the output shaft  84  via the intermeshing third intermeshing gear  52  and ninth intermeshing gear  78  to establish the third forward speed ratio. 
     To shift from the third forward speed ratio to the fourth forward speed ratio, the fourth synchronizer  68  is preselected (i.e., engaged) during the third forward speed ratio. The second shifting clutch  46  is then engaged as the first shifting clutch  42  is disengaged. The third synchronizer  66  is then disengaged. With the engagement of the second shifting clutch  46  and the fourth synchronizer  68 , torque is transferred from the input shaft  18  to the second countershaft  44  via the intermeshing second transfer gear  36  and third transfer gear  38 . Torque is transferred from the second countershaft  44  to the output shaft  84  via the fourth intermeshing gear  54  and ninth intermeshing gear  78  to establish the fourth forward speed ratio. 
     To shift from the fourth forward speed ratio to the fifth forward speed ration, the fifth synchronizer  70  is preselected (i.e., engaged) during the fourth forward speed ratio. The second shifting clutch  46  is disengaged as the first shifting clutch  42  is engaged. The fourth synchronizer  68  is then disengaged. With the engagement of the first shifting clutch  42 , torque is transferred from the input shaft  18  to the first countershaft  40  via the intermeshing first transfer gear  34  and third transfer gear  38 . The engaged fifth synchronizer  70  permits torque to be transferred from the first countershaft  40  to the output shaft  84  via the fifth intermeshing gear  56  and tenth intermeshing gear  80  to establish the fifth forward speed ratio. 
     To shift from the fifth forward speed to the sixth forward speed ratio, the sixth synchronizer  72  is preselected (i.e., engaged) during the fifth forward speed ratio. The second shifting clutch  46  is then engaged as the first shifting clutch  42  is disengaged. The fifth synchronizer  70  is then disengaged. With the engagement of the second shifting clutch  46  and the sixth synchronizer  72 , torque is transferred from the input shaft  18  to the second countershaft  44  via the intermeshing second transfer gear  36  and third transfer gear  38 , and from the second countershaft  44  to the output shaft  84  via the sixth and tenth intermeshing gears  58 ,  80 , to establish the sixth forward speed ratio. 
     The eighth, ninth, tenth and eleventh gears are a first group, each being continuously connected with the output shaft  84 . The first transfer gear  34 , and the first, third and fifth intermeshing gears  48 ,  52 ,  56 , respectively, are a second group, each being selectively interconnectable with the first shaft  40 . The second transfer gear  36 , and the second, fourth, sixth and seventh intermeshing gears  50 ,  54 ,  58  and  60  are a third group, each being selectively interconnectable with the second shaft  44 . 
     Second Embodiment: Dual Input Clutch, Countershaft Design on Three Axes with Torque Converter Clutch External to Torque Converter 
     Referring to  FIG. 2 , a vehicle  10 ′ having a powertrain  12 ′, similar to the powertrain train  12  of  FIG. 1 , is illustrated. The powertrain  12 ′ is different from that shown in  FIG. 1  in that the torque converter clutch  20 ′ is moved outside of the torque converter  16 ′. Otherwise, each of the components of the vehicle  10 ′ operates substantially the same as the correspondingly numbered components of the vehicle of  FIG. 1 . As discussed above, such relocation of the torque converter clutch enables spacing flexibility to permit an increased size and or/number of plates in the torque converter clutch and avoids the influence of torque converter pressure on the torque converter clutch. 
     Third Embodiment: Dual Input Clutch, Coaxial Shaft Design on Two Axes 
     Referring to  FIG. 3 , a vehicle  110  having a powertrain  112  including a torque converter  16  and transmission  115  is illustrated. The engine  14  and torque converter  16  are connected with the input shaft  18  in identical fashion to that of  FIG. 1 . Dual input clutches  142 ,  146  may be alternately selectively engaged to provide torque from the input shaft  18  to the first and second shafts  140 ,  144 , respectively. First, third and fifth intermeshing gears  148 ,  152 ,  156 , respectively, are selectively engageable with the first shaft  140  via the first, third and fifth synchronizers,  162 ,  166 ,  170 , respectively. Second, fourth and sixth intermeshing gears,  150 ,  154 ,  158 , respectively, are rotatable about and selectively engageable with the second countershaft  144  via second, fourth and sixth synchronizers  164 ,  168  and  172 , respectively. Additionally, a seventh or reverse gear  160  is selectively engageable with the second shaft  144  via a seventh synchronizer  174 . Eighth, ninth, tenth, eleventh, twelfth, thirteenth and fourteenth intermeshing gears  176 ,  178 ,  180 ,  182 ,  175 ,  177  and  179 , respectively, are continuously connected with an output member  184  which connects to the final drive mechanism  85 . In this embodiment, the output member  184  is a shaft, and may be referred to as an output shaft. Idler gear  186  is rotatable about an axis I and intermeshes with both the seventh/reverse gear  160  and the eleventh intermeshing gear  182 . 
     The eighth through fourteenth gears  175 ,  176 ,  177 ,  178 ,  179 ,  180 ,  182  are a first group continuously connected with the output shaft  84 . The first, third and fifth gears  148 ,  152 ,  156  are a second group, each being selectively interconnectable with the first shaft  140 . The second, fourth, sixth and seventh gears  150 ,  154 ,  158 ,  160  are a third group, each selectively interconnectable with the second shaft  144 . 
     The input shaft  18  and the coaxial first and second countershafts  140 ,  144  establish a first axis. The output shaft  184  establishes a second axis spaced form the first axis. 
     The clutches  142 ,  146  and synchronizers  162 ,  164 ,  166 ,  168 ,  170 ,  172  and  174  are selectively engageable to transfer torque through the intermeshing gears from the input shaft  18  to the output shaft  184  and establish multiple speed ratios as will be well understood by those skilled in the art based upon the description of clutch and synchronizer engagements with respect to  FIG. 1 . 
     Fourth Embodiment: Dual Output Clutch, Coaxial Shaft Design on Two Axes 
     Referring to  FIG. 4 , a vehicle  210  having a powertrain  212  including a torque converter  16  and transmission  215  is illustrated. The torque converter  16  is connected between the engine  14  and the input shaft  18  in an identical manner as that described with respect to  FIG. 1 . The transmission  215  includes a plurality of intermeshing gears some of which are continuously connected with the input shaft  18  and transfer torque to one of a first shaft  240  or a coaxial second shaft  244  depending upon synchronizer engagements. Dual output clutches  242 ,  246  are alternately selectively engageable with the first and second shaft  240 ,  244 , respectively to transfer torque to an output member  284  and to the final drive mechanism  85 . In this embodiment, the output member  284  is a shaft and may be referred to as an output shaft. 
     A first intermeshing gear  248  intermeshes with a twelfth intermeshing gear  275  which is selectively engageable with (i.e., interconnectable for rotation with) the first shaft  240  via a first synchronizer  262 . A third intermeshing gear  252  is continuously connected with the input shaft  18  and intermeshes with a thirteenth intermeshing gear  277  which is selectively engageable with the first shaft  240  via a third synchronizer  266 . A fifth intermeshing gear  256  is continuously interconnected with the input shaft  18  and intermeshes with a fourteenth intermeshing gear  279  which is selectively engageable with the first shaft  240  via a fifth synchronizer  270 . A seventh intermeshing gear  260  is continuously connected with the input shaft  18  and intermeshes with an idler gear  286  which rotates about an idler axis I. The idler gear  286  also intermeshes with an eleventh intermeshing gear  282  which is selectively engageable with the second shaft  244  via the seventh synchronizer  274 . A second intermeshing gear  250  is continuously connected with the input shaft  18  and intermeshes with an eighth intermeshing gear  276  which is selectively engageable with the second shaft  244  via a second synchronizer  264 . A fourth intermeshing gear  254  is continuously connected with the input shaft  18  and intermeshes with a ninth intermeshing gear  278  which is selectively engageable with the second shaft  244  via a fourth synchronizer  268 . A sixth intermeshing gear  258  is continuously connected and rotates with an input shaft  18 . The sixth intermeshing gear  258  intermeshes with a tenth intermeshing gear  280  which is selectively engageable with the second shaft  244  via a sixth synchronizer  272 . 
     The first, second, third, fourth, fifth, sixth and seventh gears  248 ,  250 ,  252 ,  254 ,  256 ,  258  and  260 , respectively, are a first group continuously connected with the input shaft  18 . The twelfth, thirteenth and fourteenth gears  275 ,  277  and  279 , respectively, are a second group, each being selectively interconnectable with the first shaft  240 . The eighth, ninth, tenth and eleventh gears  276 ,  278 ,  280  and  282  are a third group, each selectively connectable with the second shaft  244 . 
     The input shaft  18  establishes a first axis. The coaxial first and second shafts  240 ,  244  and the output shaft  284  establish a second axis. 
     The output clutches  242 ,  246  and synchronizers  262 ,  264 ,  266 ,  268 ,  270 ,  272  and  274  are selectively engageable to establish six forward speed ratios and a reverse speed ratio in a similar manner as described with respect to  FIG. 1 , as will be readily understood by those skilled in the art. 
     Fifth Embodiment: Dual Output Clutch, Counter Shaft Design on Three Axes 
     Referring to  FIG. 5 , a vehicle  310  having a powertrain  312  is illustrated. The powertrain  312  includes an engine  14 , a torque converter  16 , with a transmission  315  having an input shaft  18  and an output member  384 , and a final drive  385 . The torque converter  16  is connected between the engine  14  and the input shaft  18  in an identical manner to that described with respect to  FIG. 1 , above. 
     An eighth intermeshing gear  376 , a thirteenth intermeshing gear  377 , a ninth intermeshing gear  378 , a tenth intermeshing gear  380  and a fourteenth intermeshing gear  379  are continuously connected to and rotate with the input shaft  18 . First and second counter shafts  340 ,  344 , respectively, are spaced from the input shaft  18  and are substantially parallel thereto. A first intermeshing gear  348  intermeshes with an eighth intermeshing gear  376  and is selectively engageable with the first shaft  340  via a first synchronizer  362 . A third intermeshing gear  352  intermeshes with the thirteenth intermeshing gear  377  and is selectively engageable with the first shaft  340  via a third synchronizer  366 . A fifth intermeshing gear  356  intermeshes with the tenth intermeshing gear  380  and is selectively engageable with the first shaft  340  via a fifth synchronizer  370 . An idler gear  386  rotates about an idler axis I and intermeshes with the eighth intermeshing gear  376 . A seventh intermeshing gear  360  also intermeshes with the idler gear  386  and is selectively engageable with the second shaft  344  via a seventh synchronizer  374 . A second intermeshing gear  350  intermeshes with the thirteenth intermeshing gear  377  and is selectively engageable with the second shaft  344  via a second synchronizer  364 . A fourth intermeshing gear  354  intermeshes with the ninth intermeshing gear  378  and is selectively engageable with the second counter shaft  344  via a fourth synchronizer  368 . A sixth intermeshing gear  358  intermeshes with the fourteenth intermeshing gear  379  and is selectively engageable with the second shaft  344  via a sixth synchronizer  372 . First and second clutches  342 ,  346 , respectively, form dual output clutches and when selectively engaged transfer torque from the first and second shaft  340 ,  344 , respectively. The first clutch  342  may be selectively engaged to transfer torque from the first shaft  340  to a sixteenth intermeshing gear  383  which intermeshes with a seventeenth intermeshing gear  387 , which may be referred to as the final drive ring gear. The seventeenth intermeshing gear  387  may be referred to as a final drive ring gear, and intermeshes with an output differential  389  to transfer torque to the output member  384 . The second clutch  346  is selectively engageable to transfer torque from the second shaft  344  to a fifteenth intermeshing gear  381 . 
     The eighth, ninth, tenth, thirteenth and fourteenth gears  376 ,  378 ,  380 ,  377  and  379 , respectively, are a first group, each being continuously connected with the input shaft  18  for rotation therewith. The first, third and fifth gears  348 ,  352  and  356 , respectively, are a second group, each being selectively interconnectable with the first shaft  340 . The second, fourth, sixth and seventh gears  350 ,  354 ,  358  and  360 , respectively, are a third group, each being selectively interconnectable with the second shaft  344 . 
     The input shaft  18  establishes a first axis. The first and second shafts  340 ,  344 , respectively, establish second and third axes spaced from and parallel to the input shaft  18 . The output member  384  is on a fourth axis. 
     The clutches  342  and  346  as well as the synchronizers  362 ,  364 ,  366 ,  368 ,  370 ,  372  and  374  are selectively engageable to transfer torque between the input shaft  18  and the output member  384  to establish six forward speed ratios and a reverse speed ratio as will be well understood by those skilled in the art based upon the description of clutch and synchronizer engagements of  FIG. 1 . 
     Sixth Embodiment: Dual Input Clutch, Coaxial Shaft Design on Three Axes 
     Referring to  FIG. 6 , a vehicle  410  having a powertrain  412  is illustrated. The powertrain includes an engine  14  and a torque converter  16  connected between the engine  14  and the input shaft  18  in an identical manner as that described with respect to  FIG. 1 . The powertrain further includes a transmission  415  that has dual input clutches  442 ,  446  and a plurality of intermeshing gears and synchronizers selectively engageable to transfer torque from the input shaft  18  to an output member  484 . First and second clutches  442 ,  446  are alternately engageable to transfer torque from the input shaft  18  to first and second shafts  440 ,  444 , respectively. 
     A thirteenth intermeshing gear  477 , a twelfth intermeshing gear  475 , and a tenth intermeshing gear  480  are continuously connected to and rotate with the first shaft  440 . An eighth intermeshing gear  476  and a ninth intermeshing gear  478  are continuously connected to and rotate with the second shaft  444 . A second intermeshing gear  450  intermeshes with the eighth intermeshing gear  476  and is selectively engageable with a third shaft  443  via a second synchronizer  464 . A fourth intermeshing gear  454  intermeshes with the ninth intermeshing gear  478  and is selectively engageable with the third shaft  443  via a fourth synchronizer  468 . A third intermeshing gear  452  intermeshes with the thirteen intermeshing gear  477  and is selectively engageable with the third shaft  443  via a third synchronizer  466 . A first intermeshing gear  448  intermeshes with the twelfth intermeshing gear  475  and is selectively engageable with the third shaft  443  via a first synchronizer  462 . A sixteenth intermeshing gear  483  is continuously connected to shaft  443  and intermeshes with a seventeen intermeshing gear  487  (a final drive ring gear) which in turn intermeshes with a differential  489  to transfer torque to the output member  484 . 
     A sixth intermeshing gear  458  intermeshes with the ninth intermeshing gear  478  and is selectively engageable with the fourth shaft  445  via a sixth synchronizer  472 . A fifth intermeshing gear  456  intermeshes with the tenth intermeshing gear  480  and is selectively engageable with the fourth shaft  445  via a fifth synchronizer  470 . A seventh or reverse gear  460  rotates about and is selectively engageable with the fourth shaft  445  via a seventh synchronizer  474 . The first idler gear  486 A is continuously connected to a shaft that rotates about axis I and intermeshes with the seventh intermeshing gear  460  when the second clutch  446  is engaged. The second idler gear  486 B intermeshes with the twelfth intermeshing gear  475  and, although not shown geometrically in the two-dimensional layout of  FIG. 6 , is continuously connected to the same shaft that rotates about the axis I as the first idler gear  486 A and is therefore able to transfer torque between the first shaft  440  and the fourth shaft  445  when the first clutch  442  and the seventh synchronizer  474  are engaged. A fifteen intermeshing gear  481  is continuously connected with the fourth shaft  445  and, although not shown in the two dimensional schematic of  FIG. 6 , also intermeshes with the seventeenth intermeshing gear  487  to transfer torque to the differential  489  and the output member  484 , as will be well understood by those skilled in the art. The fifteenth intermeshing gear  481 , the sixteenth intermeshing gear  483 , the seventeenth intermeshing gear  487  and the differential  489  together establish a final drive  485 . 
     The tenth, twelfth and thirteenth gears  480 ,  475  and  477 , respectively, are a first group, each being continuously connected with the first shaft  440 . The first, second, third and fourth gears  448 ,  450 ,  452 , and  454 , respectively, are a second group, each being selectively interconnectable with the third shaft  443 . The fifth, sixth and seventh gears  456 ,  458  and  460 , respectively, are a third group, each being selectively interconnectable with the fourth shaft  445 . The eighth and ninth intermeshing gears  476 ,  478  are continuously connected to the second shaft  444 . 
     The input shaft and coaxial first and second shafts  440 ,  444  establish a first axis. The third and fourth shafts  443 ,  445 , respectively, establish second and third axes spaced from and parallel to the input shaft  18 . The output member  484  is on a fourth axis. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.