Patent Publication Number: US-2022219525-A1

Title: P2 module architecture

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a non-provisional patent application claiming priority to U.S. provisional application No. 62/852,331, 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 P2 module for a hybrid powertrain of 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 a device for power transmission between an output of a drive engine and an input of a transmission. 
     In one aspect, the invention provides a device for power transmission between an output of a drive engine and an input of a transmission, wherein the device includes a torque converter defining a central axis; an electric motor connected to the torque converter, the electric motor at least partially axially overlapping the torque converter; and a clutch coupled to the electric motor and the torque converter, the clutch being configured to connect and disconnect the engine with the torque converter. 
     In another aspect, the torque converter has a first axial length, and the electric motor at least partially axially overlaps the first axial length. 
     In a further aspect, the torque converter has a first axial length and the electric motor has a second axial length, the second axial length at least partially axially overlapping the first axial length. 
     In an additional aspect, the torque converter has a first axial length defining a first axial position along the central axis, the electric motor having a second axial length defining a second axial position along the central axis, the second axial position at least partially overlapping the first axial position. 
     In still another aspect, the electric motor is located radially outward of the torque converter. 
     In yet a further aspect, a damper system is provided having a damper input and a damper output, the damper input adapted to be driven by the output of the drive engine, the clutch having a clutch input connected to the damper output. 
     In another aspect, the clutch is axially positioned between the damper system and the torque converter. 
     In a further aspect, the clutch is located radially inward of the damper system. 
     In an additional aspect, the damper system at least partially axially overlaps the clutch. 
     In another aspect, the invention provides device for power transmission between an output of a drive engine and an input of a transmission, the device including a torque converter defining a central axis and having an input member, an output member and a hydrodynamic circuit coupling the input member to the output member; an electric motor having a stator and a rotor, the rotor being connected to the input member of the torque converter and at least partially axially overlapping the torque converter; a damper system having an input and an output, the input of the damper system adapted to be driven by the output of the drive engine; and a clutch coupled between the damper system and the torque converter, the clutch having a clutch input member coupled to the output of the damper system and a clutch output member coupled to the shell of the torque converter, the clutch being configured to connect and disconnect the damper with the torque converter. 
     In a further aspect, the torque converter has a first axial length defining a first axial position along the central axis, the electric motor having a second axial length defining a second axial position along the central axis, the second axial position at least partially overlapping the first axial position. 
     In an additional aspect, the second axial position is radially outward of the first axial position. 
     In yet another aspect, the clutch is an electromechanical clutch. 
     In still a further aspect, the clutch is axially positioned between the damper system and the torque converter. 
     In an additional aspect, the clutch is located radially inward of the damper system. 
     In still another aspect, the damper system at least partially axially overlaps the clutch. 
     In an additional aspect, the clutch is an electromechanical clutch. 
     In another aspect, the invention provides a device for power transmission between an output of a drive engine and an input of a transmission, the device including a torque converter having a shell defining chamber, a hydrodynamic circuit provided in the shell and configured to multiply torque inputted to the torque converter, an output hub coupled to the hydrodynamic circuit and adapted to be coupled with the input of the transmission; an electric motor located at least partially radially outward and about the torque converter, the electric motor including a stator and a rotor, the rotor being rigidly connected to the shell of the torque converter; a damper system having an input and an output, the input of the damper system adapted to be driven by the output of the drive engine; an electromagnetic clutch coupled between the damper system and the torque converter, the electromagnetic clutch having a clutch input member coupled to the output of the damper system and a clutch output member coupled to the shell of the torque converter, the electromagnetic clutch configured to connect and disconnect the damper with the torque converter; and a variable flux device located axially adjacent to the electric motor. 
     In further aspect, the torque converter has a first axial length defining a first axial position along the central axis, the electric motor having a second axial length defining a second axial position along the central axis, the second axial position at least partially overlapping the first axial position. 
     In an additional aspect, the second axial position is radially outward of the first axial position. 
     In yet another aspect, the clutch is axially positioned between the damper system and the torque converter. 
     In still a further aspect, the clutch is located radially inward of the damper system. 
     In an additional aspect, the damper system at least partially axially overlaps the clutch. 
     In another aspect, the variable flux device located axially adjacent to the rotor of the electric motor. 
     In still another aspect, the variable flux device is located radially outward of the electromagnetic clutch. 
     In yet a further aspect, the variable flux device axially overlaps the electromagnetic clutch. 
     In another aspect, the invention provides a P2 module of a hybrid powertrain for power transmission between a rotary output of a drive engine and a rotary input of a transmission, the P2 module including a torque converter having a shell defining chamber, an impeller having a plurality of impeller blades extending into the chamber and being connected to the shell, a turbine located in the shell and being supported for rotation relative to the shell, the turbine including a plurality of turbine blades generally opposing the impeller blades, an output hub rotatably supported with in the shell and coupled to the turbine, the output hub being configured to connect with the rotary input of the transmission; an electric motor located at least partially radially outward and about the torque converter, the electric motor including a stator and a rotor, the rotor being rigidly connected to the shell of the torque converter and rotatable therewith, the stator being non-rotatable; a damper system having an input adapted to be driven by the rotary output of the drive engine, the damper also having an output; an electromagnetic clutch positioned between the damper system and the torque converter, the electromagnetic clutch having a clutch input member coupled to the output of the damper system and a clutch output member coupled to the shell of the torque converter, the electromagnetic clutch being configured to connect and disconnect the damper with the torque converter; and a variable flux device located axially adjacent to the electric motor and radially outward of the electromagnetic clutch, the variable flux device at least partially axially overlapping the electromagnetic clutch. 
     In another aspect, the torque converter has a first axial length and the electric motor having a second axial length, at least 50% of the second axial length overlaps the first axial length. 
     In an additional aspect, the torque converter has a first axial length and the electric motor having a second axial length, at least 75% of the second axial length overlaps the first axial length. 
     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 a P2 module incorporating the principles of the present invention. 
     
    
    
     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 the drawing shown in  FIG. 1 , a device, a P2 module, embodying the principles of the present invention is generally illustrated therein and designated at  10 . The P2 module  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 complete engine  12  and transmission  14  are not illustrated. Rather, the respective output and input components of each are illustrated, relative to the central axis X of the P2 module  10 , and further discussed below. 
     The P2 module  10  includes as it principal components a damper system  16 , a disconnect clutch  18 , a torque converter  20 , an electric motor  22 , and a variable flux device  24 . Generally, the damper system  16  is positioned between the combustion engine  12  and the electromagnetic clutch  18 . The clutch  18  is located under the damper system  16  and between the damper system  16  and the torque converter  20 . The torque converter  20  includes a hydrodynamic circuit that can multiply input torque and output the torque to transmission  14 . The electric motor  22  is positioned radially outward of the torque converter  20  and, as such, at least partially surrounds the outer periphery of the torque converter  20 . The variable flux device  24  is located axially adjacent to the electric motor  22 . The collective use and arrangement of the components, as outlined above, advantageously reduces the axial package size of the P2 module  10  and, as will be appreciated by those skilled in the art, can be incorporated into both rear wheel drive and front wheel drive configurations. 
     The output of the combustion engine  12  is transferred by a crankshaft  26  to the damper system  16  by an input plate  28 , which is secured to the crankshaft  26  by fasteners  30  or other means. In one embodiment, and as generally illustrated, the damper system  16  includes dual mass flywheel  32  to attenuate torsional vibrations from the engine  12 . An output plate  34  of the damper system  16  couples the dual mass flywheel  32  to the input member  36  of the disconnect clutch  18 . While the damper system  16  is shown as incorporating a dual mass flywheel  32 , it will be appreciated that the damper system  16  may incorporate other vibration damping systems and/or mechanisms without departing from the scope of the present disclosure. 
     In contrast to current P2 modules, the P2 module  10  disclosed herein does not incorporate a hydraulic or wet clutch to disconnect the combustion engine  12  from the torque converter  20 . Rather, the disconnect clutch  18  of the present P2 module  10  is an electromagnetic disconnect clutch  18 . The electromagnetic disconnect clutch  18  significantly reduces the axial and radial package space requirements as compared to conventional wet or mechanical disconnect clutches. 
     The clutch  18  generally includes a fixed stator and activation coil  38  that, when energized, interacts with a translator  40  mounted of axial movement along the input member  36  of the clutch  18 . The stator and activation coil  38  are shown mounted to an inner surface of a face plate  41  forming part of the housing  43  of the P2 module  10 . Movement of the translator  40  toward the pocket plate pocket plate  42  deploys struts internal to the pocket plate  42  to engage the notch plate and transmit torque to the torque converter  20  through the clutch  18 . When the coil  38  is actuated to the disengaged position, the translator  40  is biased away from the pocket plate  42  allowing the struts to retract into the pocket plate and torque is no longer transmitted through clutch  18 . U.S. Pat. No. 9,377,061 discloses one such electromagnetic clutch and is herein incorporated by reference in its entirety. Electromagnetic clutches are generally well known and appreciated by those skilled in the art and, accordingly, variations on the clutch  18  may be used and may be required by the specific design criteria during implementing of the architecture disclosed herein. 
     As mentioned above, the notch plate  44  is fixedly connected to the torque converter  20 . More specifically, the notch plate  44  is fixed to a front cover  48  of the torque converter  20 . 
     At its radial periphery, the front cover  48  is secured to a rear cover  50  by a weld, or other suitable means, to form a fluid tight chamber  52 . The front cover  48  defines the engine side of the torque converter  20 , while the rear cover defines the transmission side of the torque converter  20 . 
     Internally, the rear cover  50  is provided with a series of blades or vanes  54  so as to form an impeller  56 . During rotation of the rear cover  50 , hydraulic fluid is supplied from the automatic transmission and is forced radially outwardly under the centrifugal force generated by the rotating impeller blades  54 . The impeller blades  54  also directs the hydraulic fluid forward, in a direction away from the rear cover  50 . In  FIG. 1 , 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  56 , the torque converter  20  includes a turbine  58 . The turbine  58  is also formed with a series of blades  60 . The turbine blades  60  are oriented to receive the hydraulic fluid from the impeller blades  54 . The force of the fluid received from the impeller  56 , as well as the shape of the turbine blades  60  themselves, rotationally drives the turbine  58  in the same direction as the rotational direction of the impeller  56 . The hydraulic fluid received by the turbine  58  is in turn re-directed inward and rearward, back to the impeller  56 . 
     Positioned between the impeller  56  and the turbine  58  is a stator  62 . The stator  62  receives the hydraulic fluid being returned from the turbine  58  to the impeller  56 . The stator  62  intercepts the fluid from the turbine  58  and redirects the fluid so that its rotational direction is aligned with the rotational direction of the impeller  56 . This redirection is conducted in such a manner that the returned hydraulic fluid is efficiently received by the impeller  56  in a manner that does not impede rotation of the impeller  56 , but that instead augments rotation allowing for a multiplication of the torque passing through the torque converter  20 . 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  62  is a one-way clutch assembly  64  that limits rotation of the stator  62  to a single direction and improves torque transfer efficiency. The one-way clutch assembly  64  includes an outer race  66  upon which the stator  62  is mounted. The one-way clutch assembly  64  also includes an inner race  68  and roller elements  70 , the latter of which are located between the outer and inner races  66 ,  68 . The inner race  68  of the one-way clutch assembly  64  is mounted upon a fixed, nonrotating support shaft (not shown) associated with the input of the transmission. In the interest of brevity, and since one-way clutch assemblies 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  64 . As such, the one-way clutch assembly  64  is not and need not be explained in greater detail. 
     The turbine  58  is supported by an output hub  72 , which is mounted on the input shaft  74  of the transmission  14 . 
     Adjacent the front cover  48  a lock-up clutch assembly  76  is provided. When engaged, the lock-up clutch assembly  76  locks rotation of the front cover  48  with the output hub  72  and the input shaft  74  of the transmission  14 , generally bypassing the fluid coupling between the impeller  56  and the turbine  58 . The lock-up clutch assembly  76  includes a clutch piston  78  radially supported by the output hub  72 . A friction plate  80  may be supported by the clutch piston  78  to engage an inner surface of the front cover  48  and a friction plate  82  supported thereby, in the lock-up condition. 
     Engagement of the lock-up clutch assembly  76  is controlled by axial movement of the clutch piston  78 . In this regard, the clutch piston  78  is radially supported on the output hub  72  so as to be axially and rotationally moveable relative to the output hub  72 . When an engaging pressure is provided from the transmission  14 , via hydraulic fluid, the clutch piston  78  is moved toward the front cover  48  and the friction plate  80  and clutch piston  78  engage the front cover  48  and the friction plate  82  supported thereby. When a disengaging pressure is provided from the transmission  14 , also via hydraulic fluid, the clutch piston  78  and its friction plate  80  are separated from the front cover  48  and its friction plate  82 . 
     Forward of the turbine  58 , generally in a position between the turbine  58  and the lock up clutch assembly  76 , the torque converter  20  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. 
     The electric motor  22  is positioned radially outward of the torque converter  20 , in a position so as to at least partially axially overlap and surround the shell of the torque converter  20 , the shell being defined by the front and rear covers  48 ,  50 . Preferably, the electric motor  22  significantly axially overlaps the torque converter  20 , meaning that greater than 50% of the electric motor&#39;s stator  84  and rotor  86  axially overlap the torque converter  20 . As illustrated, the electric motor  22  axially overlaps the torque converter by more than 75%. This overlapping construction significantly decreases the axial packing size of the P2 module  10 . As seen in the FIGURE, the torque converter  20  has an axial length L 1  defining a first axial position along the axis X and the electric motor  22  has an axial length L 2  defining a second axial position along the axis X that at least partially overlaps the first axial position. 
     The rotor  84  of the electric motor  22  rigidly and fixedly connected to the front cover  48  of the torque converter  20  by a bracket  88  orienting the rotor  86  coaxially with the central axis X. The stator  84  of the electric motor  22  it located radially outward and about the rotor  86  and is support by a bracket  90 , mounted to the housing  43 , so as to also be coaxially with the central axis X. When the electromagnetic clutch  18  is engaged and disconnects the engine  12  from the torque convertor  20 , operation of the electric motor  22  will drive the rotor  86  and input rotation into the torque converter  20  via the connection of the rotor  86  to the front cover  48 . 
     Preferably, the electric motor  22  is a torque dense, compact electric motor having as minimal a radial dimension as feasible for the design criteria of the hybrid powertrain. 
     As previously mention, a variable flux device  24  may be located axially adjacent to the electric motor  22 , and more specifically the rotor  86  of the electric motor  22 . If provided, the variable flux device  24  may be secured to the front face  41  between the rotor  86  and the damper assembly  16 . Alternatively, the damper assembly  18  may be located radially between the variable flux device  24  and the electromagnetic clutch  18 , such that the variable flux device  24  is axially positioned between the rotor  86  and the combustion engine  12 . One example of variable flux device  24  that may be used in connection with the P2 module described herein is disclosed in U.S. Patent Application Publication No. 2020/0112282 A1, published Apr. 9, 2020, which is herein incorporated by reference in its entirety. 
     During high speed operation of the electric motor  22 , the variable flux device  24  reduces back electro-motive force by accelerating collapse of the magnetic field. During starting mode operation of the vehicle, such as starting of the vehicle after stopping at a stop light, the electric motor  22  transmits torque via the rotor  86  to the torque converter&#39;s front cover  48 , through the clutch  18  and damper assembly  16  to start the engine  12 . During this starting mode, the variable flux device  24  boosts the magnetic flux during the low speed operation of the electric motor  22  increasing the electric motor torques available for starting the combustion engine  12 . 
     Immediately adjacent to the variable flux device  24 , preferably radially outward thereof, a flux device cooling jacket  90  is provided to cool the variable flux device  24 . The cooling jacket  90  may be formed as a cooling channel integrated into the face plate  41  and/or housing  43  and configured to receive cooling fluid, circulated as part of the engine&#39;s cooling circuit or independently thereof. 
     In addition to the engine start mode described above, the P2 module  10  may be operated in a mode where the just the combustion engine  12  provides torque to the torque converter  20  through the damper assembly  16  and electromagnetic clutch  18  (the electric motor  22  being off), in a mode where just the electric motor  22  provides torque to the torque converter  20  through the rotor  86  (the combustion engine  12  being off); a combined mode where both the combustion engine  12  (as noted above) and the electric motor  22  (as noted above) provide torque to the torque converter  20 , and a regeneration mode where torque is transmitted from the wheels of the vehicle, through the transmission  14  and torque converter  20 , into the electric motor  22  where the resultant electricity is used to recharge the battery of the vehicle. 
     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.