Patent Publication Number: US-2022219524-A1

Title: Integrated torque converter and p2 module

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a non-provisional application claiming priority to U.S. provisional application No. 62/852,403, filed May 24, 2019, the entire contents of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention generally relates to powertrains for motor vehicles and, more particularly, to a hybrid powertrain for a motor vehicle. 
     Description of Related Art 
     Today, the automotive industry is increasingly moving away from combustion engine vehicles and toward electric vehicles. One drawback of an all-electric vehicle (EV), however, is the current limitation on battery technology and, resultantly, the mileage range of the vehicle. While drivers who only have short range needs do not consider this a inconvenience, drivers who at least occasionally have mileage needs beyond the typical range of an all-electric vehicle must generally choose between stopping for extended periods of time to recharge the battery or owning a second vehicle for extended mileage range driving. 
     There is a bridge, however, between these two choices, hybrid vehicles (HV) and plug-in hybrid vehicles (PHEV). Plug-in hybrid vehicles first run on electricity, but utilize a gas engine backup to extend the range of the vehicle. Hybrid vehicles alternate between use of a combustion and an electric motor for higher mileage. 
     After vehicles with gas or diesel powertrains, consumers next, and increasingly, prefer vehicles with hybrid powertrains. 
     Various drivetrain architectures exist for hybrid vehicles and are known as P1, P2, P3 and P4 configurations. In a P1 configuration, the electric motor is connected to the combustion engine and located after the combustion engine. A P2 configuration locates the electric motor between the combustion engine and the transmission and allows for the combustion engine to be disconnected from the transmission. A P3 configuration locates the electric motor between the transmission and the differential. In a P4 configuration, the electric motor directly drives the axles. 
     Of these configurations the P2 configuration is considered very versatile in that it allows hybrid technology to be incorporated in to existing combustion engine powertrains with minimal modification to the existing powertrain. 
     SUMMARY 
     In view of the above, the present invention provides an assembly for power transmission between an output of a drive engine and an input of a transmission. 
     In one aspect, the invention provides an assembly for power transmission between an output of a drive engine and an input of a transmission that includes a torque converter having an input member, an output member and a hydrodynamic circuit coupling the input member to the output member, the torque converter defining a central axis; a P2 module, the P2 module including a clutch and an electric motor, with the clutch having an input member configured to connect to the output of the drive engine, the clutch having an engaged position and a disengaged position, in the engaged position the input member being connected to the torque converter, in the disengaged position the input member being disengaged from the torque converter; and with the electric motor having a stator and a rotor, the electric motor being coupled to the clutch and being drivingly coupled to the torque converter via a splined engagement. 
     In another aspect, the torque converter includes a shell having a first set of splines provided therewith, and wherein the rotor includes a second set of splines provided therewith, the first set of splines being engaged with second the splines of the rotor and forming the splined engagement. 
     In a further aspect, the torque converter includes a shell having splines formed thereon. 
     In an additional aspect, the splines protrude radially outward and extend axially. 
     In yet another aspect, the shell includes a circumferential surface, the circumferential surface being coaxial with the central axis and the splines being located on the circumferential surface. 
     In still a further aspect, the splines are unitary with the shell. 
     In an additional aspect, the splines are integral with the shell. 
     In another aspect, the clutch includes interleaved friction plates, a first set of the friction plates being rotationally fixed to an outer support plate and a second set of the friction plates being rotationally fixed to an inner support plate. 
     In a further aspect, the rotor is supported on the outer support plate. 
     In an additional aspect, the torque converter includes a shell having splines formed thereon, and wherein the outer support plate includes splines formed thereon, the splines of the torque converter being engaged with the splines of the outer support plate and forming the splined engagement. 
     In yet another aspect, the splines on the outer support plate are engaged with the first set of friction plates and rotationally fix the first set of friction plates to the outer support plate. 
     In still a further aspect, the torque converter includes a shell, a ring connected to the shell and defining a circumferential surface, a first set of splines provided on the circumferential surface, and wherein the rotor includes a second set of splines provided therewith, the first set of splines being engaged with the second set of splines and forming the splined engagement. 
     In an additional aspect, a pilot hub having a central bore, the pilot hub being coaxial with the central axis and received within the input member of the clutch, the torque converter including a mounting hub axially received within the bore of the pilot hub and axially retained therein by a retention feature configured to facilitate axial insertion of the mounting hub into the pilot hub. 
     In another aspect, the retention feature includes a snap ring radially received within a groove formed in the mounting hub, the snap ring being radially compressible. 
     In a further aspect, the axial engagement further includes a groove formed in the bore of the pilot hub, the snap ring configured to radially expand into the groove of the pilot hub upon full seating of the torque converter with the P2 module. 
     In an additional aspect, an angled trailing surface on the snap ring and a corresponding angled trailing surface on the groove of the pilot hub. 
     In yet a further aspect, the retention feature further includes a chamfer, the chamfer being provided about the bore on an entrance end of the bore. 
     In another aspect of the invention, an assembly for power transmission between an output of a drive engine and an input of a transmission is provide and includes a torque converter having an input member, an output member and a hydrodynamic circuit coupling the input member to the output member, the torque converter defining a central axis; a P2 module, the P2 module having a clutch and an electric motor, with the clutch having an input member configured to connect to the output of the drive engine, the clutch having an engaged position and a disengaged position, in the engaged position the input member being connected to the torque converter, in the disengaged position the input member being disengaged from the torque converter; and with the electric motor having a stator and a rotor, the electric motor being coupled to the clutch and being drivingly coupled to the torque converter; and where the P2 module further includes a pilot hub having a central bore coaxial with the central axis and received within the input member of the clutch, the torque converter including a mounting hub axially received within the bore of the pilot hub and axially retained therein by a retention feature configured to facilitate axial insertion of the mounting hub into the pilot hub. 
     In another aspect, the retention feature includes a snap ring radially received within a groove formed in the mounting hub, the snap ring being radially compressible. 
     In a further aspect, the axial engagement further includes a groove formed in the bore of the pilot hub, the snap ring configured to radially expand into the groove of the pilot hub upon full seating of the torque converter with the P2 module. 
     In an additional aspect, an angled trailing surface is provided on the snap ring and a corresponding angled trailing surface on the groove of the pilot hub. 
     In yet another aspect, the retention feature further includes a chamfer, the chamfer being provided about the bore on an entrance end of the bore. 
     In still a further aspect, the electric motor is drivingly coupled to the torque converter via a splined engagement. 
     In an additional aspect, the torque converter includes a shell having a first set of splines provided therewith, and wherein the rotor includes a second set of splines provided therewith, the first set of splines being engaged with second the splines of the rotor and forming the splined engagement. 
     In a further aspect, the torque converter includes a shell having splines formed thereon. 
     In an additional aspect, the splines protrude radially outward and extend axially. 
     In still another aspect, the shell includes a circumferential surface, the circumferential surface being coaxial with the central axis and the splines being located on the circumferential surface. 
     In yet a further aspect, the splines are unitary with the shell. 
     In an additional aspect, the splines are integral with the shell. 
     In another aspect, the clutch includes interleaved friction plates, a first set of the friction plates being rotationally fixed to an outer support plate and a second set of the friction plates being rotationally fixed to an inner support plate. 
     In a further aspect, the rotor is supported on the outer support plate. 
     In an additional aspect, the torque converter includes a shell having splines formed thereon, and wherein the outer support plate includes splines formed thereon, the splines of the torque converter being engaged with the splines of the outer support plate and forming the splined engagement. 
     In still another aspect, the splines on the outer support plate are engaged with the first set of friction plates and rotationally fix the first set of friction plates to the outer support plate. 
     In yet a further aspect, the torque converter includes a shell, a ring connected to the shell and defining a circumferential surface, a first set of splines provided on the circumferential surface, and wherein the rotor includes a second set of splines provided therewith, the first set of splines being engaged with the second set of splines and forming the splined engagement. 
     In another aspect, the invention provides an assembly for power transmission between an output of a drive engine and an input of a transmission, the assembly comprising a torque converter having an input member, an output member and a hydrodynamic circuit coupling the input member to the output member, the torque converter defining a central axis; a P2 module, the P2 module including a clutch and an electric motor, with the clutch having an input member configured to connect to the output of the drive engine, the clutch having an engaged position and a disengaged position, in the engaged position the input member being connected to the torque converter, in the disengaged position the input member being disengaged from the torque converter, and the clutch including interleaved friction plates, a first set of the friction plates being rotationally fixed to an outer support plate and a second set of the friction plates being rotationally fixed to an inner support plate; and with the electric motor having a stator and a rotor, the electric motor being coupled to the clutch and being drivingly coupled to the torque converter; and the torque converter further comprising a shell, wherein said shell of said torque converter is axially retained within said outer support plate by a retention feature configured to facilitate axial insertion of said shell into said outer support plate. 
     In a further aspect, the retention feature includes a snap ring radially received within a groove formed in said shell of said torque converter, said snap ring being radially compressible. 
     In an additional aspect, the electric motor is drivingly coupled to the torque converter via a splined engagement, and wherein said shell defines a circumferential surface having a first set of splines provided on the circumferential surface, with the rotor including a second set of splines provided therewith, and with the first set of splines being engaged with the second set of splines and forming the splined engagement. 
     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after review of the following description, including the claims, and with reference to the drawings that are appended to and form a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic cross-sectional view of an integrated torque converter and P2 module assembly incorporating the principles of the present invention. 
         FIG. 2  is schematic cross-sectional view of the torque converter seen in  FIG. 1 . 
         FIG. 3  is a schematic illustration of an alternative embodiment and shows an alternative location for the splined engagement. 
         FIG. 4  is an enlarged view of the axial retention feature of the integrated torque converter and P2 module assembly. 
         FIG. 5  is a schematic illustration of an alternative embodiment of the axial retention feature. 
         FIG. 6  is an enlarged view of the axial retention feature seen in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     As used in the description that follows, directional terms such as “upper” and “lower” are used with reference to the orientation of the elements as presented in the figures. Accordingly, “upper” indicates a direction toward the top of the figure and “lower” indicates a direction toward the bottom of the figure. The terms “left” and “right” are similarly interpreted. The terms “inward” or “inner” and “outward” or “outer” indicate a direction that is generally toward or away from a central axis of the referred to part whether or not such an axis is designated in the figures. An axial surface is therefore one that faces in the axial direction along the axis. A radial surface therefore faces radially, generally away from or toward the central axis. It will be understood that in actual implementation, the directional references used herein may not necessarily correspond with the installation and orientation of the corresponding components or device. 
     Referring now to  FIG. 1 , a device, an integrated torque converter and P2 module, embodying the principles of the present invention is generally illustrated therein and designated at  10 . The device  10  is positioned between the combustion engine  12  and the transmission  14  of a motor vehicle, which may be an automotive vehicle. As illustrated in  FIG. 1 , the engine  12  and transmission  14  are not illustrated in detail. Rather, the engine  12  and transmission  14  are shown coupled to the respective rotary input and output components of the device  10 , which are configured to rotate about central axis X. 
     The device  10  includes as it principal components a P2 module  16  and a torque converter  18 . The P2 module  16  further includes as its primary components a disconnect clutch  20  and an electric motor  22 , both of which are supported within a housing  23  that is rigidly mounted to the engine  12  or other fixed structure of the vehicle. 
     The output of the combustion engine  12  is typically transferred by a crankshaft (not shown) to a damper system to attenuate torsional vibrations from the engine  12 . In one embodiment, the damper system may be a dual mass flywheel damper. The output of the damper system is connected to an input member  24  of the P2 module  16 , which is rotationally supported by bushings or bearings  25  within an axial bore  27  provided in the housing  23 . While the damper system is mentioned as incorporating a flywheel, it will be appreciated that the damper system may alternatively incorporate other vibration damping mechanisms, such as a flex plate, without departing from the scope of the present disclosure. 
     As illustrated, the disconnect clutch  20  of the P2 module  16  is a hydraulic or wet clutch and is used to disconnect the combustion engine  12  from the torque converter  18  to allow the torque converter  18  to be driven exclusively by the electric motor  22 . Such clutches are well known and generally includes a series of engine side (ES) friction plates  26  (two of which are called out in  FIG. 1 ) that are connected to the input member  24  by a support plate  28 , the latter of which rotates with the input member  24 . The ES friction plates  26  are mounted to the support plate  28  so as to be rotationally fixed (and therefore rotate with) to the support plate  28 , but supported to be moveable along an axial portion  29  of the support plate  28 . 
     The ES friction plates  26  are interleaved with a series of transmission side (TS) friction plates  30  carried on a support plate  32  so as to also be rotationally fixed to the support plate  32 , but axially moveable there along. Support plate  32  is rotationally supported in the housing  23  by a support member  42  of the clutch  20  and a pilot plate  43 , both of which are further discussed below. 
     Defined within the clutch  20 , between forward chamber plate  34  and a piston plate  36 , is an engagement chamber  38 . The front chamber plate  34  is rigidly mounted to a radial wall  40  of the support member  42 , while the piston plate  36  is supported on an axial hub  44  of the support member  42  in a manner that permits axial movement of the piston plate  36  along the hub  44 . Seals  45  are provided at the various interfaces between the forward chamber plate  34 , the piston plate  36  and support member  42 . The support member  42  itself is rotationally supported by bearings  46  within the housing  23 . 
     During operation of the disconnect clutch  20 , hydraulic fluid is provided to the engagement chamber  34  from a pressurized oil circuit. The pressurized oil circuit can be supplied by the transmission or separate oil pump. As pressure in the engagement chamber  34  increases, the piston plate  36  is axially moved along the hub  44 , in the direction of the torque converter  18 , causing an active end  48  of the piston plate  36  to engage the interleaved TS and ES friction plates  30 ,  26 . Opposite of the active end  48 , on an opposing side of the interleaved TS and ES friction plates  30 ,  26 , a reaction plate  50  is rotationally and axially fixed to the support plate  32 . The force applied by the piston plate  36  and caused by the pressure in the engagement chamber  38  compresses the ES and TS friction plates  26 ,  30  against one another and between the active end  48  and the reaction plate  50 , thereby engaging the clutch  20  and causing the support plate  32  to be rotationally locked with the input member  24  and crankshaft of the engine  12 . As will be appreciated, friction material may be provided on and between engaging surfaces of the ES and TS friction plates  26 ,  30 , as well as the active end  48  and reaction plate  50 . 
     To cause disengagement of the clutch  20 , a disengagement chamber  52  is defined within the clutch  20 . To define the disengagement chamber  52 , a rear chamber plate  54  is fixedly supported on the hub  44  at a location spaced from the piston plate  36  and is configured to sealingly engage the piston plate  38 . A seal  56  may be provide one of the piston plate  36  and rear chamber plate  54  to provide for the sealed engagement. Since the disengagement chamber  52  is defined on an opposite side of the piston plate  36  from the engagement chamber  38 , when hydraulic fluid is provided to the disengagement chamber  52  and not to the engagement chamber  36 , the increased pressure in the disengagement chamber  52  will cause axial movement of the piston plate  36  away from the torque converter  18 . This movement releases the frictional engagement of the ES and TS friction plates  26 ,  30  and permits relative rotation between the plates  26 ,  30  and therefore the support plates  28 ,  32 . 
     Referring now to the electric motor  22 , the motor  22  is positioned radially outward of the disconnect clutch  20  and includes a stator  58  and rotor  60 . The stator  58  is stationarity mounted to the housing  23  of the P2 module  16 , while the rotor  60  is mounted to the support plate  32 , with a portion of the support plate  32  thereby forming an inner base or portion  62  of the rotor  60 . Being mounted to the support plate  32 , the rotor  60  is also rotatably supported by the support member  42  and the pilot plate  43 . Accordingly, when the clutch  20  is disengaged and the electric motor  22  is operated, the induced magnetic flux will cause the rotor  60 , and therefore the support plate  32 , to rotate. This rotation of the support plate  32  by the rotor  60  can be utilized in the present device  10  to provide rotary input to the torque converter  18 . 
     The pilot plate  43  is mounted at its outer periphery to the support plate/rotor base  32 ,  62  of the rotor  60 . At its inner periphery, the pilot plate  43  includes a pilot hub  63  that extends coaxially within the inner bore  65  of the input member  24 . The pilot hub  63  is supported within the bore  65  by bushings or bearings  67 . 
     As an alternative construction, the pilot plate  43  and hub  63  may be integrated into part of the stamping forming the torque converter front cover  64 . 
     As further discussed below and seen in  FIG. 2 , the torque converter  18  includes a front cover  64  that is secured to a rear cover  66  by a weld, or other suitable means, to form a fluid tight chamber  68 . The front cover  64  defines the engine side of the torque converter  18 , while the rear cover  66  defines the transmission side of the torque converter  18 . 
     To rotationally connect the torque converter  18  to the rotor  60 , the front cover  64  of the torque converter  18  is formed with a circumferential surface  70 . Preferably, the circumferential surface  70  is radially facing and coaxial with the central axis X. Provided on the circumferential surface  70  are splines  72  protruding radially outward and extending axially. Correspondingly, the inner face  74  of the rotor&#39;s base  62  is provided with splines  76 , protruding radially inward and axially, that form a mated splined engagement with the splines  72  of the torque converter&#39;s front cover  64 . The splines  72 ,  76  allow the torque converter  18  to be axially mounted and engaged with the P2 module  16  and the electric motor  22 . 
     The splines  72  of the torque converter  18  may be provided on or formed in the front cover  64 . As such, the splines  72  may be one-piece (unitary) with the front cover  64  or may be integrally mounted to the front cover  64 . The splines  76  of the rotor  60  may be provided on or formed in the base  62  of the rotor  60 . As such, the splines  76  may be one-piece (unitary) with the rotor base  62  or may be integrally mounted to the rotor base  62  or support plate  32 . 
     The splines  76  of the rotor base  62  may extend substantially the length of the support plate  32 . Extending the substantially the length of the support plate  32 , the splines  76  may additionally engage corresponding notches in the friction plates  30  so as rotationally fix the friction plates relative to the support plate  32  as mentioned above. 
     To axially retain the torque converter  18  with the P2 module  16 , the central portion of the torque converter&#39;s front cover  64  is provided with a mounting hub  78 . The mounting hub  78  is piloted into engagement with the P2 module  16  via the pilot hub  63  of the pilot plate  43 . As seen in  FIG. 4 , the mounting hub  78  includes a groove  80 , formed in an outer circumferential surface  79 , for receiving a snap ring  82 . A chamfer  81  is provided on the distal end of the mounting hub  78  so that upon insertion of the mounting hub  78  into a central bore  83  of the pilot hub  63 , generally in the direction I, the chamfer  81  will engage a chamfer  85  on the entrance end of the bore  83  and pilot the mounting hub  78  into the bore  83 . As the mounting hub  78  progresses into the bore  83 , the snap ring  82  will also engage the chamfer  85  causing the snap ring  82  to be radially compressed fully into the groove  80 . The snap ring  82  will remain fully compress in the groove  80  until the mounting hub  78  is fully seated in the pilot hub  63  and the torque converter  18  fully seated with respect to the P2 module  16 . When fully seated, the snap ring  82  will be opposed to a groove  84  formed in the bore  83  and will radially expands into the groove  84 , whereupon the snap ring  82  axially retains the torque converter  18  with the P2 module  16 . Should the torque converter  18  need to be withdrawn from the P2 module  16  for service of either component, the snap ring  82  and groove  84  are each provided with angled trailing surfaces  87 ,  89 . Upon exertion of sufficient force in direction W, the surfaces  87 ,  89  will slip relative to one another causing the snap ring  82  to be compressed into the groove  80 , thereby allowing removal of the torque converter  18  from the P2 module  16 . 
     Referring now to  FIG. 2 , internally of the torque converter&#39;s rear cover  66  is provided with a series of blades or vanes  86  so as to form an impeller  88 . During rotation of the rear cover  66 , hydraulic fluid is supplied from the automatic transmission and is forced radially outwardly under the centrifugal force generated by the rotating impeller blades  86 . The impeller blades  86  also directs the hydraulic fluid forward, in a direction away from the rear cover  66 . In  FIG. 2 , outward motion of the hydraulic fluid is toward the top of the figure and forward motion of fluid is toward the left of the figure. 
     Immediately forward of the impeller  88 , the torque converter  18  includes a turbine  90 . The turbine  90  is also formed with a series of blades  92 . The turbine blades  92  are oriented to receive the hydraulic fluid from the impeller blades  86 . The force of the fluid received from the impeller  88 , as well as the shape of the turbine blades  92  themselves, rotationally drives the turbine  90  in the same direction as the rotational direction of the impeller  88 . The hydraulic fluid received by the turbine  90  is in turn re-directed inward and rearward, back to the impeller  88 . 
     Positioned between the impeller  88  and the turbine  90  is a stator  94 . The stator  94  receives the hydraulic fluid being returned from the turbine  90  to the impeller  88 . The stator  94  intercepts the fluid from the turbine  90  and redirects the fluid so that its rotational direction is aligned with the rotational direction of the impeller  88 . This redirection is conducted in such a manner that the returned hydraulic fluid is efficiently received by the impeller  88  in a manner that does not impede rotation of the impeller  88 , but that instead augments rotation allowing for a multiplication of the torque passing through the torque converter  18 . With the inclusion of the above fluid coupling, rotation from the engine  12  is transferred as rotation to the transmission  14  of the vehicle. 
     Integrated with the stator  94  is a one-way clutch assembly  96  that limits rotation of the stator  94  to a single direction and improves torque transfer efficiency. The one-way clutch assembly  96  includes an outer race  98  upon which the stator  94  is mounted. The one-way clutch assembly  96  also includes an inner race  100  and roller elements  102 , the latter of which are located between the outer and inner races  98 ,  100 . The inner race  100  of the one-way clutch assembly  96  is mounted upon a fixed, nonrotating support shaft (not defined in the figure) associated with the input shaft  104  of the transmission  14 . In the interest of brevity, and since one-way clutch assemblies of this type are well known in the field of the present invention, those skilled in the art will really appreciate the construction and operation of the one-way clutch assembly  96 . As such, the one-way clutch assembly  96  is not and need not be explained in greater detail. 
     The turbine  90  is supported by an output hub  106 , which is mounted on the input shaft  104  of the transmission  14 . 
     Adjacent the front cover  64  a lock-up clutch assembly  108  is provided. When engaged, the lock-up clutch assembly  108  locks rotation of the front cover  64  with the output hub  106  and the input shaft  104  of the transmission  14 , generally bypassing the fluid coupling between the impeller  88  and the turbine  90 . The lock-up clutch assembly  108  includes a clutch piston  110  radially supported by the output hub  106 . A friction plate  112  may be supported by the clutch piston  110  to engage an inner surface of the front cover  64  and a friction plate  114  supported thereby, in the lock-up condition. 
     Forward of the turbine  90 , generally in a position between the turbine  90  and the lock up clutch assembly  108 , the torque converter  18  may include a damper (not shown), which operates to further absorb variations in the rotation speed of the output from the engine  12 . Dampers of this general type are well known in the field of the present invention and those skilled in the art will really appreciate the possible constructions, variation and operations of such a damper. Accordingly, the damper is not be explained in further detail herein. 
     Referring now to  FIG. 3 , an alternative construction for rotationally connecting the P2 module  16  to the torque converter  18  is schematically illustrated therein. In this construction, a carrier plate  116  is mounted to the front cover  64  of the torque converter  18  by welding, mechanical fasteners or other means. The carrier plate  116 , which is shown in cross-section for clarity, includes a ring  118  extending axially from the front cover  64 . The ring  118  further includes an outer circumferential surface  120  upon which are provided splines  122 . The splines  122  are provided so as to matingly engage the splines  76  provided on the support plate  32  and inner base  62  of the rotor  60 , as discussed above. The carrier plate  116 , including the ring  118  and splines  122  may be formed by various means, including fabrication or stamping. 
     With the above construction, the electric motor  22  and disconnect clutch  20  are not affected by axial movement or forces resulting for ballooning of the torque converter&#39;s shell (front and rear covers  64 ,  66 ). Additionally, because of the wholly axial aspect of the assembling of the torque converter  18  with the P2 module  16 , installation methods are flexible and allow the P2 module  16  to be provide and shipped as an assembly or as separate subsystems for later assembly at the time of assembly with the torque converter  18 . 
     With reference to  FIGS. 5 and 6 , the torque converter  18  has the input member, the output member and the hydrodynamic circuit coupling the input member to the output member. The torque converter  18  defines a central axis X. The P2 module  16  includes the clutch  20  and the electric motor  22 . The clutch  20  has the input member configured to connect to the output of the engine  12 . The clutch  20  has an engaged position and a disengaged position. In the engaged position the input member is connected to the torque converter  18 . In the disengaged position the input member is disengaged from the torque converter  18 . The clutch  20  includes the interleaved friction plates, the first set of the friction plates  30  being rotationally fixed to the outer support plate  32  and the second set of the friction plates  26  being rotationally fixed to the inner support plate  28 . The electric motor  22  has the stator  58  and the rotor  60 , the electric motor  22  being coupled to the clutch  20  and being drivingly coupled to the torque converter  18 . 
     As shown in  FIGS. 5 and 6 , the torque converter  18  further includes the shell  64 ,  66  (front cover  64  and rear cover  66 ). The shell  64 ,  66  of the torque converter  18  is axially retained within the outer support plate  32  by a retention feature  200 . In one embodiment, the front cover  64  is axially retained within the outer support plate  32  by the retention feature  200 . The retention feature  200  is configured to facilitate axial insertion of the shell  64 ,  66  into the outer support plate  32 . 
     The retention feature  200  in  FIGS. 5 and 6  may include a snap ring  202  radially received within a groove  204  formed in the shell  64 ,  66  of the torque converter  18 , with the snap ring  202  being radially compressible. 
     The electric motor  22  may be drivingly coupled to the torque converter  18  via a splined engagement. The shell  64 ,  66  defines a circumferential surface  206  having a first set of splines  208  provided on the circumferential surface  206 . The rotor  60  includes a second set of splines  210  provided therewith. The first set of splines  208  are engaged with the second set of splines  210  and form the splined engagement. 
     The above description is meant to be illustrative of at least one preferred implementation incorporating the principles of the invention. One skilled in the art will really appreciate that the invention is susceptible to modification, variation and change without departing from the true spirit and fair scope of the invention, as defined in the claims that follow. The terminology used herein is therefore intended to be understood in the nature of words of description and not words of limitation.