Engine disconnect devices with mechanical diodes for vehicle engines / drive trains

Abstract

Motor flexplate assembly for effectively coupling a motor (14) to a hydrokinetic torque converter (18) of a motor vehicle (10), wherein the motor (14) has a motor output shaft (15) and the torque converter (18) has a torque converter (TC) housing with a front plate (32) welded to a pump housing part (31) of the TC housing, wherein the motor flexplate assembly comprises: a motor flex plate (34) with a disc-shaped body (57) having front and back sides and a central hub, which is designed for rigid attachment with its front side to the motor output shaft (15) for common rotation with it; and a separating device (60) in the form of a freewheel, which is positioned on the rear of the disc-shaped body (57) of the motor flex plate (34) and includes concentric inner and outer running rings (64, 164, 66, 166), wherein the outer bearing ring (66, 166) surrounds the inner bearing ring (64, 164) and wherein one of the inner and outer bearing rings (64, 164, 66, 166) is rigidly attached to the disc-shaped body (57) for common rotation or is formed integrally with it, and the other of the inner and outer bearing rings (64, 164, 66, 166) is rigidly attached to the front plate (32) of the TC housing for common rotation or is formed integrally with it, wherein the separating device (60) is designed to effectively separate the motor output shaft (15) from the front panel (32) of the TC housing when a torque transmitted between them reverses direction.

Description

INTRODUCTION

[0001] The present invention relates generally to motor vehicle engines / drivetrains. More specifically, aspects of this invention relate to an engine flexplate assembly with disconnect devices for effectively disengaging torque converters of internal combustion engines.

[0002] Many available motor vehicles, such as modern automobiles, contain an engine / drivetrain that operates to propel the vehicle and power the onboard electronics. The engine / drivetrain, which includes a powertrain and is sometimes inappropriately referred to as a driveline, essentially consists of an engine that delivers motive power via a multi-speed powershift transmission to the vehicle's axle drive system (e.g., rear differential, axle, and wheels). Automobiles are traditionally powered by a reciprocating internal combustion engine (ICE) due to its ready availability and relatively low cost, light weight, and overall efficiency. Such engines include 2- or 4-stroke diesel engines and 4-stroke gasoline engines.

[0003] On the other hand, hybrid vehicles use alternative energy sources to power the vehicle, minimizing the engine's dependence on energy and thereby increasing overall fuel efficiency. A hybrid electric vehicle (HEV), for example, integrates both electrical energy and chemical energy and converts them into mechanical power to propel the vehicle and power the vehicle's systems. The HEV generally uses one or more electric machines (E-machines), such as electric motor-generators, working individually or in conjunction with an internal combustion engine to propel the vehicle. Because hybrid vehicles can derive their power from sources other than the engine, engines in hybrid vehicles can be turned off while the vehicle is powered by the alternative energy source(s).

[0004] Many automotive vehicles utilize a hydrodynamic torque converter positioned between the prime mover of the powertrain (e.g., engine) and a driven load (e.g., multi-speed transmission) to control the transfer of rotational torque therebetween. A conventional torque converter includes an impeller coupled to the engine output shaft, a turbine coupled to the transmission input shaft, and a stator positioned between the impeller and turbine to regulate fluid flow between their respective fluid volumes. A hydraulic pump modulates hydraulic fluid pressure within the torque converter housing to transfer rotational energy from the impeller to the turbine. Hydraulic fluid can also be branched off from the housing.to increase slip or to otherwise effectively disengage the engine crankshaft from the transmission input shaft and multiply torque (e.g., function as a pseudo-reduction gear) to compensate for or offset significant differences between input and output speeds. For exemplary torque converters, reference is made to US 2 333 680 A and KR 10 0 820 400 B1, which describe torque converters with an integrated one-way clutch. In contrast, US 3 354 746 A and DE 12 01 185 A describe torque converters with an integrated one-way clutch.

[0005] A torque converter can generally be characterized or typified as a fluid coupling that allows the engine to transfer power to the axle drive system for propulsion of a vehicle, and allows the crankshaft to rotate without stalling the engine when the vehicle's wheels and transmission gears come to a stop. For example, when the engine is rotating slowly (e.g., when the vehicle is braking to a stop or idling at a stop light), hydraulic pressure between the pump and turbine is reduced so that the amount of torque passed through the torque converter is very small, allowing the vehicle to be held stationary with a light application of a brake pedal. To accelerate the vehicle, the pump increases internal fluid pressure, causing increased amounts of torque to be transferred from the impeller through the turbine to the transmission to launch the vehicle.For manual transmissions, the torque converter is typically replaced by a driver-operated clutch that is engaged and disengaged by a foot pedal.

[0006] Some torque converters are equipped with a clutch mechanism that engages to rigidly connect the engine crankshaft to the transmission input shaft when their speeds are nearly equal, e.g., to prevent unwanted slippage and resulting efficiency losses. System "slip" occurs because the speed of the impeller is inherently different with respect to the turbine in the torque converter. A large percentage of slip between the engine output and the transmission input affects the vehicle's fuel consumption; the use of a torque converter clutch (TCC) helps reduce the slip between the engine and transmission. The TCC works to mechanically lock, or lock, the impeller at the engine output with the turbine at the transmission input so that the engine output and transmission input rotate at the same speed.An application of TCC can be controlled by an electronic controller to modify clutch engaging forces under certain operating conditions, for example during gear shifts, to eliminate unwanted torque fluctuations and changes in engine speed during transient periods when an interruption in torque flow is desired. SUMMARY

[0007] Disclosed herein are flexplates having an integrated engine disconnect device, methods of making and methods of using such engine flexplates, and motor vehicles having an engine flexplate operatively coupled / decoupled to / from a hydrokinetic torque converter via an intermediate disconnect device. For example, a novel engine disconnect device in the form of a passive one-way clutch (OWC) or a selectable one-way clutch (SOWC) is installed between the torque converter (TC) housing and the engine hub, integrated with the engine flexplate. In the form of a passive OWC or SOWC, an annular inner race thereof is rigidly mounted for common rotation with the faceplate of the TC housing, while an annular outer race is rigidly mounted for common rotation with the engine flexplate.This configuration allows the crankshaft, via the flexplate, to automatically or selectively overrun or freewheel the TC mainshaft to prevent inadvertent engine stall. An engine starter can be located on the outer perimeter of the flexplate to selectively drive the engine crankshaft for engine starting. Some system architectures allow the torque converter to float to accommodate ballooning, while some designs require that any ballooning movement be accommodated by the one-way clutch mechanism.

[0008] Associated benefits for at least some of the disclosed concepts include improved engine disconnect capabilities for hybrid vehicles during idle / coast and electric vehicle (EV) operating modes. These features are most effective for P2 / P2.5 / P3 / P4 hybrid-electric architectures (P2 = transmission input electric motor; P2.5 = transmission-mounted electric motor; P3 = transmission output electric motor; P4 = electric motor directly connected to the final drive). With the proposed system architecture and control methodology, increased fuel efficiency and extended EV range are realized with minimal additional cost and package space for the motor / powertrain.

[0009] The invention is based on the object of providing an engine flex plate assembly which enables automatic separation of the crankshaft from the torque converter with little technical effort in order to prevent unwanted stalling of the engine, particularly in hybrid vehicles.

[0010] This object is achieved with a motor flex plate assembly having the features of claim 1.

[0011] Other aspects of the present invention are directed to motor vehicles with engine disconnect devices. A "motor vehicle," as used herein, may include any relevant vehicle platform, such as passenger cars (internal combustion engine (ICE), hybrid, electric, fuel cell, etc.), commercial vehicles, industrial vehicles, tracked vehicles, all-terrain vehicles (ATV), agricultural equipment, marine vessels, aircraft, etc. In one example, a motor vehicle is disclosed that includes a vehicle engine / driveline having an internal combustion engine operatively coupled to an axle drive system via a multi-speed powershift transmission. A torque converter assembly operatively connects the output shaft of the internal combustion engine to the input shaft of the powershift transmission.This torque converter assembly features a torque converter (TC) housing with a front plate connected to a pump cover to define an internal fluid chamber. Within this fluid chamber, rotating turbine blades are arranged side by side with rotating impeller blades.

[0012] The vehicle's engine / driveline also includes an engine flexplate with a disc-shaped body. The flexplate's disc-shaped body has a central hub rigidly attached at its front to a motor hub for common rotation with the engine output shaft. A disconnector is disposed between the engine flexplate and the torque converter. The disconnector comprises a mechanical diode with concentric inner and outer annular races. The outer annular race is rigidly coupled to the disc-shaped body of the engine flexplate assembly for common rotation therewith. In contrast, the inner annular race is rigidly coupled to the front plate of the TC housing for common rotation therewith.The disconnect device is designed to free-wheel the motor output shaft and thereby effectively disconnect it from the front panel of the TC housing when torque transmitted therebetween reverses direction.

[0013] According to other aspects of the present invention, methods of manufacturing and methods of using automotive engine disconnect devices with mechanical diodes are presented. For example, a method is disclosed for constructing an engine flexplate assembly for operatively coupling an engine to a motor vehicle hydrokinetic torque converter.The method comprises: forming a disc-shaped flexplate body having front and rear sides and a central hub configured on the front side thereof for attachment to the engine output shaft for common rotation therewith; positioning a separator on the rear side of the disc-shaped body, the separator having concentric inner and outer races, the inner race configured for attachment to the front plate of the TC housing for common rotation therewith; and attaching the outer race to the disc-shaped body for common rotation therewith. The separator, when properly assembled, is configured to effectively separate the engine output shaft from the front plate of the TC housing when torque transmitted therebetween reverses direction. The attaching step may comprise integrally forming the outer race with the flexplate body.Similarly, the inner race can be formed integrally with the front plate of the TC housing. Alternative designs may include attaching the inner race of the separator to the flexplate body and fabricating the outer race for rigid attachment to the front plate of the TC housing.

[0014] The above summary is not intended to represent every embodiment or aspect of the present invention. Rather, the foregoing summary merely provides an exemplary illustration of some of the novel aspects and features set forth herein. The above features and advantages and other features and advantages of the present invention will be readily apparent from the following detailed description of representative embodiments and modes for carrying out the present invention when taken in conjunction with the accompanying drawings and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic illustration of a representative motor vehicle having an engine / driveline with an axle drive system drivingly connected to an engine through a power transmission, in accordance with aspects of the present invention. Fig. 2 is a side cross-sectional view of a portion of the powershift transmission of Fig. 1, which shows a representative flexplate assembly with an integrated motor disconnect device according to aspects of the present invention. Fig. 3 is a side cross-sectional view of a portion of the powershift transmission of Fig. 1, which shows a representative flexplate assembly with another integrated motor disconnect device according to aspects of the present invention. Fig. 4A and Fig. 4B are block diagrams of a workflow for a method or algorithm that may correspond to instructions executed by an engine logic circuit of an on-board electronic engine controller for operating a controllable engine disconnect device in accordance with aspects of the present invention. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0015] This invention is capable of embodiment in many different forms. Representative embodiments of the invention are shown in the drawings and are herein described in detail, it being understood that the present invention is to be considered as an exemplary illustration of the principles of the invention. As such, elements and limitations disclosed in, for example, the abstract, summary, and detailed description sections, but not explicitly recited in the claims, should not be incorporated into the claims, individually or collectively, by incorporation, inference, or otherwise. For the purposes of this Detailed Description, unless specifically excluded: the singular includes the plural and vice versa; the terms "and" and "or" are intended to be both conjunctive and disjunctive; the term "all" means "all"; the term "any" or"any" means "all"; and the terms "including," "comprising," and "having" mean "including without limitation." Furthermore, terms of approximation such as "about," "nearly," "substantially," "approximately," and the like may be used herein to mean, for example, "at, near, or nearly at," or "within 3-5% of," or "within acceptable manufacturing tolerances," or any logical combination thereof.

[0016] Referring now to the drawings, wherein like reference characters refer to like features throughout the several views, in Fig. 1 is a schematic illustration of a representative automobile, designated as a whole by 10, having a P3 hybrid electric motor / powertrain configuration. The illustrated automobile 10—also referred to herein as a “motor vehicle” or “vehicle” for brevity—is merely one exemplary application with which the novel aspects of this invention may be practiced. Likewise, the implementation of the present concepts in a P3 hybrid electric architecture is also to be recognized as an exemplary application of the novel concepts disclosed herein. As such, it is to be understood that the aspects and features of the present invention may be incorporated into other vehicle engine / powertrain embodiments and utilized for any logically relevant type of motor vehicle. Finally, the hybrid engine / powertrain architecture disclosed in Fig. 1 is greatly simplified, it being understood that further information relating to the standard design and operation of a hybrid vehicle is known.

[0017] The exemplary engine / drivetrain system of a vehicle is shown in Fig. 1 with a restartable engine 14 drivingly connected to an axle drive system 16 through a multi-stage powershift transmission 12. The engine 14 transmits power, preferably by means of torque via an engine crankshaft 15, to an input side of the transmission 12. The transmission 12, in turn, is adapted to manipulate and distribute power from the engine 14 to the axle drive system 16, represented herein by a differential 17 and a pair of drive wheels 19, and thereby propel the hybrid vehicle. In the Fig. 1, the engine 14 may be any engine known today or developed in the future, such as a 2-stroke or 4-stroke diesel or a 4-stroke gasoline engine, which is readily capable of providing its available power output typically at several revolutions per minute (rpm). Although in Fig. 1, it should be understood that the axle drive system 16 may include any known configuration, e.g., front-wheel drive (FWD), rear-wheel drive (RWD), four-wheel drive (4WD), all-wheel drive (AWD), etc.

[0018] Fig. 1 also illustrates selected components of the electro-hydraulic transmission 12, which includes a main housing 11 enclosing first and second electric motor / generator assemblies B1, B2, respectively. These motor / generators B1, B2 may be indirectly mounted, preferably through a series of planetary gear sets (not shown), on a main shaft 21 of the transmission 12. The motor / generators B1, B2 operate with one or more selectively engageable, torque-transmitting mechanisms (e.g., clutch, brake, etc., not shown herein) to rotate the transmission output shaft 20. An oil pan or sump volume 23 is located on the bottom of the main housing 11 and is adapted to receive hydraulic fluid, such as (in Fig. 1 hidden at 13) to provide transmission oil to the transmission 12 and its components. The main housing 11 encloses the innermost components of the transmission 12, such as the motor / generators B1, B2, planetary gear assemblies, mainshaft 21, and torque-transmitting devices (all mentioned for illustrative purposes and not all shown). Additionally, an auxiliary pump 25 is mounted at the bottom of the main housing 11 and nestably secured adjacent the oil pan 23. Finally, a hydrodynamic torque converter assembly, indicated as a whole at 18, is operatively positioned between the engine 14 and transmission 12.

[0019] Fig. 2 is a side cross-sectional view of a portion of the representative torque converter assembly 18. The hydrokinetic torque converter assembly 18 is a fluid coupling for operatively connecting the ICE 14 to the epicyclic gear train of the powershift transmission 12. The torque converter assembly 18 includes a torque converter impeller 22, a turbine 24 with blades, a stator 26, a lock-up or bypass clutch 28, and a torsional damper assembly 30. To protect these components, the torque converter assembly 18 is configured with an annular housing primarily defined by a pump housing portion 31 that is securely attached to an engine-side faceplate 32 via, for example, electron beam welding, MIG or MAG welding, laser welding, and the like, such that a chamber 35 for a working hydraulic fluid is formed therebetween. A motor flex plate 34 is connected to the front plate 32 of the TC housing e.g.connected via a one-way clutch 60 to drivingly connect the torque converter assembly 18 to the crankshaft 15 of the engine 14 - by means of an engine hub 33 - so that rotational power can be transferred back and forth therebetween.

[0020] The impeller 22, also referred to in the art as the "pump," is in serial power flow fluid communication with the turbine 24. Disposed between the impeller 22 and the turbine 24 is a stator 26 which selectively alters a fluid flow returning from the turbine 24 to the impeller 22 such that returning fluid assists rather than hinders rotation of the impeller 22. The transmission of engine torque from the crankshaft 15 to the turbine 24 via the annular housing faceplate 32 and the impeller 22 is accomplished through the use of a hydraulic fluid, such as gear oil 13, in the fluid chamber 35. More specifically, rotation of the impeller blades 27, which are held between the pump housing 31 and an inner shell 37, causes the hydraulic fluid 13 to be directed toroidally outward toward the turbine 24.When this occurs with sufficient force to overcome the inertial resistance to rotation, the turbine blades 29, which are coaxially oriented with the impeller blades 27 and held between the inner shroud 37 and a turbine casing 39, begin to rotate with the impeller 22. The fluid flow leaving the turbine 24 is redirected into the impeller 22 by the stator 26. The stator 26, located between the flow exit section of the turbine 24 and the flow inlet section of the impeller 22, redirects the fluid flow from the turbine 24 to the impeller 22 in the same direction as impeller rotation, thereby reducing pumping torque and causing torque multiplication.

[0021] Also disposed within the housing of the torque converter assembly 18 are a pair of thrust bearings 36 that rotatably support the stator 26. The stator 26 is connected to a stator shaft 38 by means of a roller clutch 40, which serves to prevent rotation of the stator 26 at low torque converter speeds. At higher torque converter speeds, the direction of hydraulic fluid 13 leaving the turbine 24 changes, causing the stator 26 to overrun, or freewheel, the roller clutch 40 and rotate freely on the stator shaft 38. The impeller 22 is attached to a pump hub 50, whereas the turbine 24 is rotatably mounted on a TC output shaft 46. As shown, a turbine hub 49 is disposed between the turbine 24 and the TC output shaft 46 and is configured to operatively couple them together.The turbine hub 49 is secured to the turbine housing 39, for example, by a plurality of rivets 47 and engages the TC output shaft 46 through a splined interface 51.

[0022] Because the internal combustion engine 14 operates at various speeds, it can inherently generate torsional vibrations (colloquially known as "torsional vibration"). For example, when fuel is being supplied to the engine 14 and it is running or operating under power, e.g., due to engagement of the fuel throttle (not shown) during normal operation, the engine 14 can generate torsional vibrations that one does not want transmitted to and through the transmission 12. In addition, when the engine 14 is not being fueled or is not running under power (e.g., during a start-up and / or shutdown cycle), the engine pistons can generate compression pulses. Both the torsional vibrations and the compression pulses can produce resulting vibrations and noise that may be perceived by a vehicle occupant.

[0023] In order to cancel or compensate for the torsional vibrations and compression pulses that can be generated by the engine 14, the torque converter assembly 18 is equipped with a torsional damper assembly 30, as shown in Fig. 2. As will be described in detail later below, the torsional damper assembly 30 generally serves to isolate the transmission 12 from undesirable torsional vibrations generated by the engine 14 during operation and also to selectively assist the one or more motor / generator assemblies in smoothing out engine compression pulses during startup and shutdown operations.

[0024] The torsional damper assembly 30 includes an annular damper flange 42 having one or more spring-mass damper systems, hereinafter referred to as "SDS," and designated as a whole by 44, circumferentially spaced around and positioned proximate its outer periphery. The damper flange 42 is rigidly coupled to a clutch plate 52 of a lock-up clutch 28 via a rivet 41 or secured thereto by brazing, a mechanical fastener, molding, etc. The engine-side front plate 32, as described above, is secured to the engine crankshaft 15 by the connection between the flexplate 34 and a crankshaft guide (not shown).In addition to operating to transmit torque generated by the engine 14 to the transmission 12, the flexplate 34 also serves to absorb axial loads that may be generated by the hydrodynamics of the torque converter 18 and / or by operation of the lock-up clutch 28.

[0025] Within a fluid cavity 43 adjacent the turbine housing 39 is a lock-up clutch 28 (also referred to herein as a torque converter clutch (TCC)) for providing a direct drive connection between the engine 14 and the transmission 12. The lock-up clutch 28 includes a clutch plate 52 operable to selectively frictionally engage a friction surface or material 48 with an inner contact surface 45 of the faceplate 32. The clutch plate 52 is slidably supported at its annular clutch hub portion 53 on a proximal end of the TC output shaft 46. For at least some embodiments, the clutch plate 52 moves in response to hydraulic fluid, i.e., transmission oil 13, being fed into the fluid cavity 43 from an oil source, such as a sump volume 23. When the lock-up clutch 28 is fully engaged (iewhen there is no slippage between the friction material 48 and the surface 45 of the faceplate 32), the impeller 22 is frictionally coupled to the turbine 24 so that the two components rotate as a single unit, allowing the engine 14 to effectively bypass the torque converter assembly 18 and transfer power directly to the transmission 14 without any efficiency losses associated with using the hydraulic fluid 13.

[0026] With reference to Fig. 2, the front plate 32 acts in conjunction with an annular extension 54 of a driven plate (also referred to herein as a "damper tab") to sandwich the TCC 28 and torsional damper assembly 30 therebetween. The damper tab 54 is attached or connected at its base portion to the turbine housing 39, for example, by the turbine hub 49 and the rivet 47, and serves to mechanically engage and thereby actuate the individual SMS 44. The damper tab 54 includes a plurality of individual, in Fig. 2 as 55, each extending axially into a respective seating portion of the damper flange 42. As the TC lock-up clutch 28 is engaged (i.e., the friction material surface 48 on the clutch plate 52 is urged against a contact surface 45 of the face plate 32 by the use of the hydraulic fluid 13) and begins to transmit torque (i.e., amplify torque capacity independently of the turbine 24), the torsional damper assembly 30 is rotated about its central axis. As a result of this rotational movement, a spring retainer of each SMS 44 is pressed against a respective flange portion 55 of the damper nose 54, thereby compressing the springs 56. This interaction can be utilized to absorb and dampen unwanted torsional vibrations generated by the engine 14 during normal, start-up, and shutdown operations, as some examples.

[0027] In the illustrated example, the motor flex plate 34 consists of a disc-shaped body 57 with a forward-facing “front” side (e.g. in Fig. 2 pointing to the right in the direction of the engine 14), which is opposite a rear-facing “back” side (e.g. in Fig. 2 pointing left toward the transmission 12). An integral central hub 59 of the flexplate body 57 is rigidly attached at its front to the engine output shaft 15 for common rotation therewith. As illustrated, the central hub 59 is formed with circumferentially spaced bolt holes 61; each hole 61 receives a respective flexplate bolt (not shown) therethrough, which threadably engages a complementary internally threaded hole 63 in the engine hub 33 to thereby rigidly couple the engine flexplate 34 to the engine output shaft 15. For at least some embodiments, it is desirable that the flexplate body 57 be constructed of a sufficiently resilient metallic material that allows the flexplate 34 to flex about its central axis to accommodate movement between the engine 14 and the torque converter 18 as speeds change.A series of teeth 62, collectively defined as a “starter ring gear,” projects radially outward from an outer diameter (OD) edge of the flexplate body 57 and is operatively engaged with a toothing 63 of a motor starter.

[0028] An engine disconnect device is installed between the engine flexplate 34 and the torque converter assembly 18—positioned at the rear of the disc-shaped body 57—to effectively disconnect the hydrokinetic torque converter 12 from the internal combustion engine 14. According to one example, this disconnect device may take a variety of different mechanical diode designs designed for high locking torque along with a nearly wear-free overrunning or freewheeling operation. While it is preferable for at least some embodiments that the disconnect device include a passively actuated (passive) clutch mechanism, it is also conceivable that the device adopts designs of a selectively actuated (active) clutch mechanism. According to the Fig. 2, the disconnect device is a passive one-way clutch (OWC) mechanism 60 directly coupled to both the TC housing faceplate 32 and the engine flexplate 34. To utilize existing packaging space within the engine / powertrain envelope, the OWC 60 may be sandwiched between the ICE 14 and the torque converter 18, nested within a pocket jointly defined by the TC housing and the flexplate. In this architecture, the OWC 60 is disposed in a series powerflow connection with the ICE 14 upstream of the power transmission 12 and torque converter 18.

[0029] The OWC 60 disconnect device serves to automatically and effectively connect (or "lock") the crankshaft 15 and hub 33 to the TC faceplate 32 and thus to the impeller housing 31 when a speed ratio therebetween is at or above a preset threshold speed ratio (e.g., a positive torque is transmitted at approximately 0.98:1.00). Conversely, the OWC 60 serves to automatically and effectively disconnect (or "overrun") the crankshaft 15 from the impeller 22 when the speed ratio therebetween is below the aforementioned preset threshold speed ratio and / or when the torque reverses direction. Fig. 2, the OWC 60 includes concentric inner and outer annular races 64, 66, respectively. The inner race 64 is shown integrally formed with the TC housing faceplate 32 for common rotation therewith, but may otherwise be rigidly attached thereto. Conversely, the outer race 66 is shown integrally formed with the disc-shaped body 57 for common rotation therewith, but may otherwise be rigidly attached thereto. A plurality of circumferentially spaced rollers 68 are disposed between and rotatably coupling the inner and outer races 64, 66 of the OWC 60. These rollers 68 may be spring-loaded, e.g., via individual coil springs (not shown), to permit free-running rotational movement of the outer race 66 with respect to the inner race 64 in a first direction, but to lock the two races 64, 66.to prevent rotational movement in the opposite direction. Alternative designs may include clamps, elements with ratchet teeth and claws, spring-loaded rollers, etc., instead of or in addition to the rollers 68.

[0030] Fig. 3 provides a cross-sectional view of the torque converter assembly 18 of Fig. 1, which shows a flexplate assembly 134 with an alternative integrated engine disconnect device installed between the engine 14 and the torque converter assembly 18. According to the Fig. 3, the disconnect device is a selectively actuated (active) selectable one-way clutch (SOWC) 160 that is directly coupled to both the TC housing faceplate 132 and the engine flexplate 134. For at least some embodiments, the SOWC 160 is an electrically actuated multi-mode clutch mechanism. Like the OWC 60 of Fig. 2 includes the SOWC 160 of Fig. Three concentric inner and outer annular races 164 and 166, respectively. The inner race 164 is shown integrally formed with the front plate 132 of the TC housing for common rotation therewith, but may otherwise be rigidly attached thereto. Conversely, the outer race 166 is shown integrally formed with the disc-shaped body 157 for common rotation therewith, but may otherwise be rigidly attached thereto.

[0031] The SOWC 160 from Fig. 3 is provided with a series of circumferentially spaced claws 168 disposed between the inner and outer races 164, 166. These claws 168 are selectively movable from an engaged position, in which the claws 168 lock the inner and outer races 164, 166 together, to a disengaged position, in which the claws 168 allow the races 164, 166 to rotate freely, thereby separating the engine output shaft 15 from the front plate 132. According to one example, the SOWC 160 includes an electromechanical solenoid 170 with a wrap spring 172. When an electrical current is applied to the solenoid 170, the wrap spring 172 contracts, moving the jaws 168 to the engaged position to thereby lock the inner and outer races 164, 166 together.For at least some embodiments, each of the claws 168 is placed in a respective one of a plurality of pockets 174 formed in the inner and / or outer races 164, 166. Each pocket 174 is cut or otherwise elongated in the axial direction (e.g., in . Fig. 3 from left to right) to allow axial movement of the respective claw 168. This design allows the SOWC 160, specifically the claws 168, to accommodate any ballooning movement of the TC housing during operation of the torque converter 18. Optional designs may utilize hydraulically driven solenoids or other means of selective actuation.

[0032] Fig. 4A and Fig. 4B present a method or methods for operating the OWC 60 of Fig. 2 or the SOWC 160 from Fig.3. During a normal operating mode, the disconnect device transfers torque from the engine 14 to the torque converter 18. For example, the disconnect device's OWC is freewheeling during an engine shutdown operation. When engine braking is requested, the disconnect device is engaged / disengaged into the lock-lock mode to enable the transfer of torque between the axle drive and the engine. For example, for operation in the engage-lock mode, method 400 begins at block 401 by generating an ENGINE BRAKE COMMAND ON (manual shift) signal. Method 400 proceeds to block 403 to determine if the disconnect device is freewheeling. If the disconnect device is freewheeling (403 = YES), method 400 proceeds to block 405 to synchronize the device (clutch) speed.If the separator is not freewheeling (403 = NO), method 400 proceeds to block 407 to engage the lock-lock mode.

[0033] If the system wishes to return to a normal operating mode, the lock-lock mode is turned off and, if the engine is in braking mode, the engine speed must be increased to properly disengage. For example, for operation in disengage-lock mode, method 400 begins at block 409 by generating an ENGINE BRAKE COMMAND OFF signal. Method 400 proceeds to block 411 to determine if the disconnect device (clutch) is under load for engine braking. If the disconnect device is under load (411 = YES), method 400 proceeds to block 413 to apply positive torque. If the disconnect device is not under load (411 = NO), method 400 proceeds to block 415 to disengage a lock-lock mode.

Claims

[1] An engine flexplate assembly for operatively coupling an engine (14) to a hydrokinetic torque converter (18) of a motor vehicle (10), the engine (14) having an engine output shaft (15) and the torque converter (18) having a torque converter (TC) housing with a faceplate (32) welded to a pump housing portion (31) of the TC housing, the engine flexplate assembly comprising: a motor flexplate (34) comprising a disc-shaped body (57) having front and rear sides and a central hub adapted for rigid attachment with its front side to the motor output shaft (15) for common rotation therewith; and a separating device (60) in the form of a freewheel, which is positioned on the rear side of the disc-shaped body (57) of the motor flex plate (34) and contains concentric inner and outer races (64, 164, 66, 166), wherein the outer race (66, 166) surrounds the inner race (64, 164) and wherein one of the inner and outer races (64, 164, 66, 166) is rigidly attached to the disc-shaped body (57) for common rotation therewith or is formed integrally therewith and the other of the inner and outer races (64, 164, 66, 166) is rigidly attached to the front plate (32) of the TC housing for common rotation therewith or is formed integrally therewith, wherein the separating device (60) is adapted to effectively separate the motor output shaft (15) from the front plate (32) of the TC housing when a torque transmitted therebetween reverses a direction. [2] The engine flexplate assembly of claim 1, wherein the separating device (60) is a passively actuated clutch mechanism or a selectively actuated clutch mechanism. [3] The engine flexplate assembly of claim 2, wherein the separating device (60) is a selectable one-way clutch (SOWC) (160) in the case of a selectively actuated clutch mechanism. [4] The engine flexplate assembly of claim 3, wherein the SOWC is an electrically actuated multi-mode SOWC (160). [5] The engine flexplate assembly of claim 4, wherein the SOWC (160) includes an electromechanical solenoid (170) having a wrap spring (172) configured to selectively contract to brake a selector plate of the SOWC (160) and thereby lock the inner and outer races (166, 164) together. [6] The engine flexplate assembly of claim 3, wherein the SOWC includes a plurality of claws (168) disposed between the inner and outer races (166, 164), the claws (168) being selectively movable from engaged to disengaged positions to thereby separate the engine output shaft (15) from the faceplate (32). [7] The engine flexplate assembly of claim 6, wherein each of the claws (168) is placed in a respective one of a plurality of pockets (174) formed in the inner or outer race, each of the pockets (174) being cut in an axial direction to allow axial movement of the respective claw (168) to thereby accommodate ballooning movement of the TC housing. [8] The engine flexplate assembly of claim 2, wherein the separating device (60) is a passive one-way clutch (OWC) (60) in the case of a passively actuated clutch mechanism. [9] The engine flexplate assembly of claim 8, wherein the OWC (60) includes a plurality of rollers (68) rotatably coupling the inner race (64) to the outer race (66). [10] The engine flexplate assembly of claim 8, wherein the outer race (66) is integrally formed with the disc-shaped body (57).

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