CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. provisional application no. 63/184,693, filed May 5, 2021, the entire contents of which are herein incorporated by reference.

[0002] BACKGROUND

1. Field of the Invention

[0003] The present invention generally relates to powertrains for motor vehicles and, more particularly, to a P2 module for a hybrid powertrain, such as would be utilized in an automotive vehicle.

2. Description of Related Art

[0004] Today, the automotive industry is increasingly moving away from combustion engine vehicles and toward electric vehicles. While the technology is improving, one drawback of an all-electric vehicle (EV) is the current limitation on battery technology and, resultantly, the mileage range of such vehicles. While drivers who only have short range needs do not consider this a inconvenience, drivers who at least occasionally have mileage needs beyond the range of a typical all-electric vehicle must generally choose between stopping for extended periods of time to recharge the battery or owning a second vehicle that does have an extended driving range. [0005] There is, however, a bridge between these two choices. That bridge includes hybrid vehicles (HV) and plug-in hybrid vehicles (PHEV). Hybrid vehicles alternate between use of a combustion engine and an electric motor to power the vehicle. The net effect being a higher effective gas mileage than a combustion engine vehicle, but lower than an EV. Plug-in hybrid vehicles run on electricity as their primary power source, but will utilize a combustion engine as a backup power source to extend the range of the vehicle.

[0006] While vehicles with strictly gas or diesel powertrains are currently the preference of consumers, next, and increasingly, consumers prefer vehicles with hybrid powertrains.

[0007] Various drivetrain architectures exist for hybrid vehicles. These hybrid architectures are generally known as PI, P2, P3 and P4 configurations. In a PI 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, but the electric motor is not connected to the combustion engine. As such, a P2 configuration allows the combustion engine to be disconnected from the transmission when not in use. A P3 configuration locates the electric motor between the transmission and the differential. In a P4 configuration, the electric motor directly drives the axles.

[0008] Of these configurations, the P2 configuration is considered very versatile since it allows hybrid technology to be incorporated in to existing combustion engine powertrains with minimal modification to the existing powertrain. As the automotive industry moves toward hybrid vehicles, a compact P2 module is needed to facilitate packaging of the module in existing vehicle architectures, particularly in vehicles having a front wheel drive configuration.

[0009] A P2 module have a conventional configuration is illustrated in FIG. 1. As seen therein, a damper (not shown) fills the empty space to the left of the electric motor and a hydraulic disconnect clutch is mounted radially inside of the electric motor. The rotor of the electric motor is constrained axially by a portion of the clutch cylinder, which is in turn secured to the torque converter. This mechanism of axially constraining the rotor increases the axial packaging of the P2 module.

SUMMARY

[0010] In view of the above, the present invention provides a device for power transmission between the output of an engine and the input of a transmission.

[0011] The device is a compact P2 module which provides an architecture that decreases the required axial packaging over know designs and, therefore, renders the P2 module efficient for integration in vehicles having front wheel drive configurations, as well as integration into vehicles have rear wheel drive configurations.

[0012] In one aspect the invention provides a compact P2 module including a torque converter, a connect/disconnect clutch assembly and an electric motor having a rotor axially restrained by the torque converter.

[0013] In another aspect, the invention provides a compact P2 module including a torque converter, a connect/disconnect clutch assembly and an electric motor. The torque converter having a shell defined by a front cover and a rear cover and further including an impeller and a turbine coupled to one another so as to form a hydrodynamic circuit. The connect/disconnect clutch assembly includes a clutch cylinder and the electric motor includes a stator and a rotor, with the rotor being mounted to the clutch cylinder and being axially constrained by engagement with the front cover of the torque converter.

[0014] In another aspect, the rotor is in direct engagement with the front cover.

[0015] In a further aspect, the rotor is axially and directly engaged with the front cover.

[0016] In an additional aspect, the rotor is in physical, axial engagement with the front cover.

[0017] In yet another aspect, the rotor is fixed to the front cover.

[0018] In still a further aspect, the rotor is directly fixed to the front cover.

[0019] In an additional aspect, the rotor is not directly fixed to the front cover.

[0020] In another aspect, a rotor/ shell retainer, the rotor/ shell retainer rotationally securing the rotor to the shell.

[0021] In yet a further aspect, the rotor/ shell retainer is in direct engagement with the shell.

[0022] In still an additional aspect, the rotor/shell retainer is in fixed engagement with the shell.

[0023] In another aspect, the rotor/shell retainer is in indirect engagement with the rotor.

[0024] In a further aspect, the rotor/shell retainer is in secured engagement with the clutch cylinder.

[0025] In an additional aspect, the rotor/shell retainer is engaged with the clutch cylinder for rotation therewith.

[0026] In still another aspect, the engagement between rotor/shell retainer and the clutch cylinder is a splined engagement.

[0027] In yet a further aspect, the engagement between rotor/shell retainer and the clutch cylinder is an axially constrained engagement.

[0028] In an additional aspect, the rotor/shell retainer includes a groove defined on a radially outward surface and the clutch cylinder includes a groove defined on a radially inward surface, a retaining member being located in the both the groove of the rotor/shell retainer and the groove of the clutch cylinder.

[0029] In another aspect, the retaining member is a snap ring. [0030] 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 DRAWINGS

[0031] FIG. 1 illustrates a P2 module having an architecture in accordance with the prior art.

[0032] FIG. 2 illustrates a P2 module having an architecture incorporating the principles of the present invention.

[0033] FIG. 3 illustrates an axial retaining feature utilized with the architecture seen in

FIG. 2.

DETAILED DESCRIPTION

[0034] 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 drawing. 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. When used, 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 access is designated in the figures. An axial surface is therefore one that faces in the axial direction. In other words, an axial surface faces in a direction along the central axis. A radial surface therefore faces radially, generally away from or toward the central axis. It will be understood, however, that in actual implementation, the directional references used herein may not necessarily correspond with the installation and orientation of the corresponding components or device.

[0035] Referring now to the drawing shown in FIG. 2, 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 an internal combustion engine 12 and a transmission 14 of a motor vehicle. As illustrated in FIG. 2, 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 connect/disconnect clutch assembly 16 (in the form of a K0 clutch assembly), a torque converter 18, an electric motor 20 and a resolver 22.

[0036] Generally, a damper system 24 is positioned between the internal combustion engine 12 (hereafter “engine 12”) and the P2 module 10. The output of the engine 12 is transferred by a crankshaft 26 to an input plate 28 of the damper system 24, which is secured to the crankshaft 26 by fasteners 30 or other means. While shown as incorporating a dual mass flywheel 32, it will be appreciated that the damper system 24 may incorporate other vibration damping systems and/or mechanisms without departing from the scope of the present invention. An output plate 34 of the damper system 24 couples the dual mass flywheel 32 to the input member 36 of the connect/disconnect clutch assembly 16. This coupling of the output plate 34 to the input member 36 of the connect/disconnect clutch assembly 16 is preferably achieved through a splined engagement 38.

[0037] The architecture of the P2 module 10 is such that the connect/disconnect clutch assembly 16 and the resolver 22 are both located axially between the damper system 24 and the torque converter 18 and are both generally located radially inward of the electric motor 20. The resolver 22 is itself located radially between the connect/disconnect clutch assembly 16 and the stator of the electric motor 20. Additionally, the resolver 22 is positioned radially inward of the diameter defined by the torque converter 18 and is connected between the connect/disconnect clutch assembly 16 and the housing 40 of the P2 module 10.

[0038] The connect/disconnect clutch assembly 16 is used to disconnect the engine 12 from the transmission 14 when the vehicle is being operated in electric mode (driven by the electric motor 20) or coasting.

[0039] The connect/disconnect clutch assembly 16 is a friction clutch assembly and includes a clutch housing 41, which defines a clutch cylinder 42, a clutch hub 44, outer friction plates 46 and inner friction plates 48. The clutch housing 41 includes an axial extension that defines a cylinder. This axially extending portion of the clutch housing 41, which is unitarily formed with the clutch housing 41, is herein referred to as the clutch cylinder 42.

[0040] The clutch hub 44 is supported on the input member 36 so as to be fixed for rotation therewith. Accordingly, the engagement of the clutch hub 44 and the input member 36 may be a splined engagement. The inner friction plates 48 are provided on an axial extension of the clutch hub 44, via a splined engagement, so as to be located radially outward of the axial extension. [0041] The clutch housing 41 is supported by the housing 40 for relative rotation with respect thereto. To permit relative rotation between the clutch housing 41 and the housing 40, the clutch housing 41 is rotatably supported by a bearing 50. Interleaved with the inner friction plates 48, the outer friction plates 46 are in splined engagement with an inner surface of the axial extension, i.e. the clutch cylinder 42, of the clutch housing 41.

[0042] Engagement and disengagement of the connect/disconnect clutch assembly 16 is further discussed below.

[0043] The torque converter 18 provides a hydrodynamic circuit that is configured to multiply an input torque and transmit the increased torque as an output torque to the transmission 14 of the vehicle. The torque converter 18 includes a front cover 52 and a rear cover 54 that cooperate to define a shell 56. The shell 56 further defines an internal chamber 58 where the hydrodynamic circuit is provided.

[0044] Rotational input to the torque converter 18 is received by the front cover 52 and transferred to an impeller 60, which is internally attached to the rear cover 54 of the shell 56. The impeller 60 directs the hydrodynamic fluid radially outward and then axially forward, toward a turbine 62. The force imparted on the turbine 62 by the fluid rotationally drives the turbine 62. From the turbine 62, the fluid is directed radially inward and subsequently axially back toward the impeller 60. A stator 64, position between the turbine 62 and the impeller 60, redirects the fluid so as to efficiently transfer the fluid to the impeller 60, thereby multiplying the torque being transferred.

[0045] The turbine 62 is connected to a turbine hub 66, and the turbine hub 66 transfers the output torque to the input member 68 of the transmission 14. A damper assembly, not shown, may be provided in the torque converter 18 for NVH isolation before transfer of the output torque to the vehicle’s transmission 14. A lock-up clutch assembly 70 is also provided to allow the torque converter 18 to lock its input from the front cover 52 with the turbine hub 66 so that the output being transmitted to the transmission 14 bypasses the hydrodynamic circuit of the impeller 60 and turbine 62.

[0046] The stator 72 of the electric motor 18 is located radially outward of the electric motor’s rotor 74, and has a diameter that is larger than the diameter than the torque converter 18. As such, the stator 72 and a portion of the electric motor may axially overlap with the shell 56 of the torque converter 18. The rotor 74 of the electric motor 18 and has an outer diameter approximating the outer diameter of the torque converter 18. The inner diameter of the rotor 74 is therefore less than the outer diameter of the torque converter 18.

[0047] Being of a K0 clutch configuration, the connect/disconnect clutch assembly 16 is located between the front cover 52 of the torque converter 18 and the output 26 of the internal combustion engine 12. The connect/disconnect clutch assembly 16 provides a connected/disconnected path between torque converter’s front cover 52, the resolver 22 and the output 26 of the engine 12.

[0048] The compactness of the architecture of the P2 module 10 disclosed herein results from a novel mechanism for axially constraining the rotor 74 of the electric motor 20. This retention feature employs the front cover 52 of the torque converter 18, a rotor/ shell retainer 76, the clutch cylinder 42 of the connect/disconnect clutch assembly 16 and a snap ring 80.

[0049] As seen in FIG. 2, the rotor 74 of the electric motor 20 is rotatably fixedly on the exterior of the axial extension defined by the clutch cylinder 42. Accordingly, the rotor 74 and the clutch cylinder 42 rotate in unison. A rotor/shell retainer 76 is fixedly attached to the front cover 52 of the torque converter 18 and is used to concentrically hold the rotor 74 and clutch cylinder 42 with the torque converter 18. The rotor/shell retainer 76 is also rotationally fixed to the clutch cylinder 42 and, therefore, the rotor 52. In this regard, the radially outer surface of the rotor/shell retainer 76 and radially inner surface of the clutch cylinder 42 are in a splined engagement 78. To axially retain the clutch housing 41 relative to the rotor/shell retainer 76, a snap ring 80 of the rotor/shell retainer 76 securely engages with a groove 82 provided in the clutch cylinder 42, as seen in FIG. 3.

[0050] Referring back to FIG. 2, the rotor 74 is configured to directly engage the front cover 52 in an axial direction. As such the front cover 52 directly operates as the physical axial constraint to the rotor 74 of the electric motor 20 in the direction of the front cover 52/torque converter 18. By directly utilizing the front cover 52 as an axial constraint for the rotor 74, the axial packaging requirement of the P2 module 10 is advantageously reduced. With its reduced axial packaging, the present architecture is more susceptible to integration with existing front wheel drive configurations, as well as with rear wheel drive configurations.

[0051] To form the direct axial constraint mentioned above, the exterior of the rotor 74 is in direct contact with the front cover 52 of the torque converter 18. The rotor 74 is not, however, directly fixed to the front cover 52, although the rotor 74 may optionally be directly fixed to the front cover 52 by various or may be frictionally engaged with the front cover 52. Also optionally, the rotor 74 may be directly rotationally constrained with the front cover 52 via a geared or similar engagement on the axial end of the rotor 74 and the adjacent surface of the front cover 52.

[0052] As noted above, the connect/disconnect clutch assembly 16 is used to disconnect the engine 12 from the transmission 14 when the vehicle is being operated in electric mode (driven by the electric motor 20) or coasting.

[0053] Engagement and disengagement of the connect/disconnect clutch assembly 16 is controlled by a clutch piston 84. The clutch piston 84 is normally biased by a spring 86 or other biasing member such that the connect/disconnect clutch assembly 16 is disengaged. In other words, torque is not being transferred via the outer and inner friction plates 46, 48 from the clutch hub 44 to the clutch cylinder 42. This position is seen in FIG. 2. When engaging pressure, preferably via hydraulic fluid, is provided to an engagement pressure chamber 88, the clutch piston 84 is moved in a direction against the biasing force of the spring 86 and toward a reaction plate 90. As a result, the outer periphery, designated at 92, of the clutch piston 84, forces engagement of the outer friction plates 46 with the inner friction plates 48. The engagement of the inner and outer friction plates 48, 46 locks the clutch hub 44 to the clutch cylinder 42 and therefore locks the output plate 34 of the damper system 24, and therefore the crankshaft 26 and output of the engine 12, with the front cover 52 of the torque converter 18. Upon release of the engaging pressure in the pressure chamber 88, the spring 86, in conjunction with the axially fixed reaction plate 90, axially disengages clutch piston 84 from the friction plates 46, 48 by moving the clutch piston 84 back to its biased position, a direction that is axially away from the torque converter 18 in FIG. 2. [0054] The description provided herein 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.