Patent Publication Number: US-10760624-B1

Title: Wedge-type selectable one-way clutches for engine disconnect devices of motor vehicle powertrains

Description:
INTRODUCTION 
     The present disclosure relates generally to motor vehicle powertrains. More specifically, aspects of this disclosure relate to engine disconnect devices with attendant control logic and hydraulic hardware for hybrid electric powertrains. 
     Current production motor vehicles, such as the modern-day automobile, are originally equipped with a powertrain that operates to propel the vehicle and power the vehicle&#39;s onboard electronics. In automotive applications, for example, the vehicle powertrain is generally typified by a prime mover that delivers driving power through an automatic or manually shifted power transmission to the vehicle&#39;s final drive system (e.g., differential, axle shafts, road wheels, etc.). Automobiles have historically been powered by a reciprocating-piston type internal combustion engine (ICE) assembly due to its ready availability and relatively inexpensive cost, light weight, and overall efficiency. Such engines include two and four-stroke compression-ignited (CI) diesel engines, four-stroke spark-ignited (SI) gasoline engines, six-stroke architectures, and rotary engines, as some non-limiting examples. Hybrid and full electric vehicles, on the other hand, utilize alternative power sources to propel the vehicle and, thus, minimize or eliminate reliance on a fossil-fuel based engine for tractive power. 
     A full electric vehicle (FEV)—colloquially referred to as an “electric car”—is a type of electric-drive vehicle configuration that altogether removes the internal combustion engine and attendant peripheral components from the powertrain system, relying solely on electric traction motors for propulsion and for supporting accessory loads. The engine, fuel supply system, and exhaust system of an ICE-based vehicle are replaced with an electric motor, a traction battery back, and battery cooling and charging electronics in an FEV. Hybrid vehicle powertrains, in contrast, employ multiple sources of tractive power to propel the vehicle, most commonly operating an internal combustion engine assembly in conjunction with a battery-powered or fuel-cell-powered electric motor. A hybrid electric vehicle (HEV), for example, is generally equipped with an ICE assembly and an electric machine (E-machine), often in the form of a motor/generator unit (MGU), that operate individually or cooperatively to generate tractive power. Since hybrid vehicles are able to derive their power from sources other than the engine, HEV engines may be turned off, in whole or in part, while the vehicle is propelled by the electric motor(s). 
     There are three basic hybrid vehicle powertrain architectures: parallel hybrid, series hybrid, and series-parallel (“power-split”) hybrid configurations. Series hybrid architectures, for example, derive all tractive power from electric motors and therefore eliminate any driving mechanical connection between the engine and final drive members. In this case, the engine functions solely as a regenerative energy source, driving an electric generator that charges the vehicle&#39;s onboard traction battery pack. In parallel hybrid architectures, the engine and motor/generator assemblies each has a driving mechanical coupling to the power transmission and, thus, the vehicle&#39;s road wheels. As the name implies, series-parallel hybrid architectures combine features from both parallel hybrid and series hybrid powertrains. With gas-only and electric-only operating modes, the engine and motor work independently or jointly—in parallel or in series—depending on the desired vehicle speed, overall vehicle power demand, and state-of-charge (SOC) of the battery. 
     Vehicle powertrains employing an automatic transmission commonly insert a hydrodynamic torque converter between the internal combustion engine and the multi-speed transmission to govern the transfer of rotational power therebetween. Torque converters are designed to selectively transmit power from the engine to the drivetrain system for vehicle propulsion, and to allow the crankshaft to spin without the engine stalling when the vehicle wheels and transmission gears come to a stop. Replacing the mechanical clutch of a manual transmission, a standard torque converter (TC) acts as a fluid coupling with a fluid impeller that is connected to the engine&#39;s output shaft, a turbine that is connected to the transmission&#39;s input shaft, and a stator interposed between the impeller and turbine to regulate fluid flow between their respective fluid volumes. A hydraulic pump modulates fluid pressure within the torque converter housing to regulate the transfer of rotational energy from the impeller to the turbine. A large difference in speed between the impeller and turbine results in torque multiplication of the impeller torque, as for example when the vehicle is accelerating from rest with the engine running. 
     Some torque converters are equipped with an internal clutch mechanism that is engaged to rigidly connect the engine&#39;s crankshaft to the transmission&#39;s input shaft when their speeds are nearly equal, e.g., to avoid unwanted slippage and resultant efficiency losses. System “slip” occurs because the rotational speeds of the impeller relative to the turbine in the torque converter are inherently different. A large slip percentage between the engine output and transmission input affects the fuel economy of the vehicle; employing a torque converter clutch (TCC) helps to significantly reduce the slip. The TCC operates to mechanically lock the impeller at the output of the engine to the turbine at the input of the transmission so that the engine output and transmission input rotate at the same speed. Application of the TCC may be controlled by a powertrain control module (PCM) to modify clutch engaging forces under certain operating conditions, for example, during clutch-to-clutch shifts to eliminate undesired torque fluctuations and engine speed changes during transient periods when torque flow interruption is desired. 
     One of the many available types of parallel hybrid powertrains is the parallel two-clutch (P2) architecture, which may be typified by a single engine, an automatic power transmission, and a single motor/generator unit that is “side attached” to the transmission in parallel power-flow communication to the engine. Mechanically interposed between the engine and motor/generator unit is a disconnect clutch that, unlike the TCC discussed above, drivingly disengages the engine from both the MGU and transmission such that the MGU can be operated independent of the engine to propel the vehicle. P2 architectures help to reduce system costs over counterpart hybrid powertrains by eliminating the use of additional MGUs and reducing the complexity of the transmission. The P2 architecture also helps to eliminate engine friction during regenerative braking operations, and allows the motor/generator to spin at higher speeds while recovering more energy. 
     SUMMARY 
     Disclosed herein are wedge-type selectable one-way clutches (SOWC), methods for making and methods for operating such SOWCs, hybrid powertrain architectures using such SOWCs as engine disconnect devices, and motor vehicles equipped with such wedge-type SOWC engine disconnect devices. By way of example, there are presented P2 parallel hybrid powertrains with wedge-type SOWCs for drivingly connecting and disconnecting an internal combustion engine to/from the vehicle&#39;s drivetrain. In a representative architecture, a wedge-type SOWC selectively disconnects the engine from the torque converter, traction motor, and automatic transmission in order to maximize regeneration energy, e.g., resulting from regenerative braking. The wedge-type SOWC is packaged between the engine&#39;s crankshaft and the torque converter&#39;s outer housing, with the inner race of the SOWC drivingly connected to the flexplate and the outer race of the SOWC drivingly connected to the TC pump cover. A wedge plate is interposed between and transfers torque across the SOWC&#39;s inner and outer races. The wedge plate is slidably mounted inside grooves and pockets that are respectively recessed into facing surfaces of the outer and inner race. This wedge plate may be actively disengaged, e.g., via the torque converter&#39;s internal charge pressure or an electronic solenoid, such that the SOWC freewheels in both forward (positive) and reverse (negative) directions. 
     Attendant benefits for at least some of the disclosed SOWC engine disconnect device configurations include powertrain architectures that help to mitigate rotational backlash and resultant noise during transient vehicle operation, including transitions between motor-only and motor-assist operating modes. In addition to improving noise, vibration, and harshness (NVH) performance, disclosed features also help to improve engine disconnect response time for hybrid vehicles during coasting and motor-only operating modes. With proposed hybrid powertrain architectures and control methodologies, increased fuel economy and reduced emissions are realized with minimal additional cost and powertrain packaging space. Disclosed SOWC designs also help to minimize packaging space requirements by reducing the axial length of the engine disconnect device. 
     Aspects of this disclosure are directed to wedge-type SOWC engine disconnect devices for managing the transfer of torque between an internal combustion engine assembly and a hydrodynamic torque converter assembly. In an example, an engine disconnect device is presented for operatively disconnecting an engine from a torque converter. The engine disconnect device includes annular inner and outer races, with the inner race concentrically aligned inside the outer race. The outer (or inner) race splines to, integrally forms with, bolts/rivets on, or otherwise attaches to the torque converter, e.g., via the pump cover of the TC housing, to rotate in unison therewith. An inner diameter (ID) surface of the outer race is fabricated with multiple recessed grooves that are circumferentially spaced from one another. In addition, the inner (or outer) race attaches to the engine&#39;s output shaft, e.g., via an engine hub and/or flexplate, to rotate in unison therewith. An outer diameter (OD) surface of the inner race is fabricated with multiple recessed pockets that are circumferentially spaced from one another. 
     Continuing with the above example, a wedge plate is positioned between the OD and ID surfaces of the inner and outer races, respectively. The wedge plate may be fabricated as a single-piece structure with a (continuous or discontinuous) annular shape and multiple circumferentially spaced ramps. Each ramp has a radial width that progressively decreases or otherwise varies in a circumferential direction with respect to the wedge plate. In addition, each ramp is slidably mounted within one of the outer race&#39;s grooves and one of the inner race&#39;s pockets. The wedge plate is movable between an engaged (first) position and a disengaged (second) position. When the wedge plate is in the first position, the ramps frictionally wedge between the ID and OD surfaces; the wedged ramps transfer torque between the inner and outer races. Conversely, when in the second position, the ramps unwedge from between the ID and OD surfaces; unwedging the ramps operates to free the inner race to rotate with respect to the outer race. The engine disconnect device may optionally include a selector plate that is selectively actuable, e.g., via a hydraulic piston or an electronic solenoid, to move between deactivated and activated states to thereby move the wedge plate between the first and second positions, respectively. 
     Additional aspects of this disclosure are directed to electric-drive vehicles and hybrid electric powertrains equipped with SOWC engine disconnect devices. As used herein, the term “motor vehicle” may include any relevant vehicle platform, such as passenger vehicles (ICE, HEV, BEV, PHEV, etc.), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles (ATV), motorcycles, farm equipment, watercraft, aircraft, etc. Disclosed features may be most effective for, but are certainly not limited to, P2/P2.5/P3/P4 hybrid electric architectures (P2=E-machine on transmission input side; P2.5=E-machine on transmission; P3=E-machine on transmission output side; P4=E-machine direct connect to axle drive). In an example, a motor vehicle includes a vehicle body with multiple road wheels, and an internal combustion engine mounted to the vehicle body and including a crankshaft for outputting engine-generated torque. A multi-speed transmission receives, modifies, and transmits torque that is output by the ICE assembly to one or more of the vehicle wheels to thereby propel the motor vehicle. A torque converter assembly operatively connects the ICE assembly to the transmission to govern the transfer of torque therebetween. 
     Continuing with the above example, the motor vehicle is also equipped with an engine disconnect device that is located between the engine and torque converter. The engine disconnect device includes an annular outer race that rigidly attaches, either directly or indirectly, to a pump cover of the TC assembly for common rotation therewith. An ID surface of the outer race includes multiple recessed grooves that are circumferentially spaced from one another. An annular inner race is concentrically aligned within the outer race and attached, either directly or indirectly, to the crankshaft for common rotation therewith. An OD surface of the inner race includes multiple recessed pockets that are circumferentially spaced from one another. An annular wedge plate, which is interposed between the inner and outer races, includes multiple circumferentially spaced ramps. Each ramp has a variable radial width and is slidably mounted within a respective groove and a respective pocket. The wedge plate rotates between an engaged (first) position, whereat the ramps frictionally wedge between the ID and OD surfaces to thereby transfer torque between the inner and outer races, and a disengaged (second) position, whereat the ramps unwedge from between the ID and OD surfaces to thereby free the inner race to rotate with respect to the outer race. 
     Other aspects of the disclosure are directed to methods for making and methods for using any of the disclosed engine disconnect devices, powertrains, and vehicles. In an example, a method is presented for assembling an engine disconnect device. This representative method includes, in any order and in any combination with any of the above and below disclosed options and features: attaching an outer race to input structure of a torque converter assembly for common rotation therewith, the outer race including an ID surface with circumferentially spaced, recessed grooves; attaching an inner race to an engine output shaft for common rotation therewith, the inner race being concentrically aligned within the outer race and including an OD surface with circumferentially spaced, recessed pockets; and positioning a wedge plate between the inner and outer races, the wedge plate including circumferentially spaced ramps, each of the ramps having a variable radial width and being slidably mounted within a respective one of the grooves and a respective one of the pockets, the wedge plate being movable between a first position, whereat the ramps frictionally wedge between the ID and OD surfaces and transfer torque between the inner and outer races, and a second position, whereat the ramps unwedge from between the ID and OD surfaces and, in this manner, free the inner race to rotate with respect to the outer race. 
     The above summary is not intended to represent every embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel concepts and features set forth herein. The above features and advantages, and other features and attendant advantages of this disclosure, will be readily apparent from the following detailed description of illustrated examples and representative modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and subcombinations of the elements and features presented above and below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a representative electric-drive motor vehicle with a hybrid powertrain having an engine assembly drivingly connected to a multi-speed power transmission and an electric motor/generator unit by a SOWC engine disconnect device in accordance with aspects of the present disclosure. 
         FIG. 2  is an exploded, perspective-view illustration of select portions of a representative hydrodynamic torque converter assembly, back-to-back SOWC engine disconnect device, engine flexplate, and torsional damper assembly in accordance with aspects of the present disclosure. 
         FIG. 3  is a cross-sectional side-view illustration of select components presented in  FIG. 2 . 
         FIG. 4  is a front-view illustration of the representative back-to-back SOWC engine disconnect device of  FIG. 2  as seen in the direction of section line arrows  4 - 4 . 
         FIG. 5  is an exploded, perspective-view illustration of select portions of a representative hydrodynamic torque converter assembly, pawl-type SOWC engine disconnect device, engine flexplate, and torsional damper assembly in accordance with aspects of the present disclosure. 
         FIGS. 6-8  are schematic illustrations of the representative pawl-type SOWC engine disconnect device of  FIG. 5  showing the selector plate drive a spring-biased wedge to shift a pawl-bearing notch plate insert seated inside a notch of the notch plate. 
         FIG. 9  is a graph of hydraulic pressure vs. time for a representative TC internal fluid chamber illustrating use of torque converter clutch (TCC) apply and release pressures for the activation and deactivation of a TCC and an engine disconnect clutch (EDC). 
         FIG. 10  is a schematic illustration of a representative hydraulic circuit for activating and deactivating a TCC and EDC using TCC apply and release pressures in accordance with aspects of the present disclosure. 
         FIG. 11  is a is a flowchart illustrating a representative SOWC control algorithm for activating and deactivating an engine disconnect device, which may correspond to memory-stored instructions executed by onboard and/or remote control-logic circuitry, programmable electronic control unit, or other computer-based device or network of devices in accord with aspects of the disclosed concepts. 
         FIG. 12  is a cross-sectional, side-view illustration of select portions of a representative hydrodynamic torque converter assembly, wedge-type SOWC engine disconnect device, engine flexplate, and torsional damper assembly in accordance with aspects of the present disclosure. 
         FIG. 13  is a cross-sectional, side-view illustration of select portions of a representative hydrodynamic torque converter assembly, another representative wedge-type SOWC engine disconnect device, engine flexplate, and torsional damper assembly in accordance with aspects of the present disclosure. 
       The present disclosure is amenable to various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, subcombinations, permutations, groupings, and alternatives falling within the scope of this disclosure as encompassed by the appended claims. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure is susceptible of embodiment in many different forms. Representative embodiments of the disclosure are shown in the drawings and will herein be described in detail with the understanding that these embodiments are provided as an exemplification of the disclosed principles, not limitations of the broad aspects of the disclosure. To that extent, elements and limitations that are described, for example, in the Abstract, Introduction, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise. 
     For purposes of the present detailed description, unless specifically disclaimed: the singular includes the plural and vice versa; the words “and” and “or” shall be both conjunctive and disjunctive; the words “any” and “all” shall both mean “any and all”; and the words “including,” “containing,” “comprising,” “having,” and the like, shall each mean “including without limitation.” Moreover, words of approximation, such as “about,” “almost,” “substantially,” “generally,” “approximately,” and the like, may each be used herein in the sense of “at, near, or nearly at,” or “within 0-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof, for example. Lastly, directional adjectives and adverbs, such as fore, aft, inboard, outboard, starboard, port, vertical, horizontal, upward, downward, front, back, left, right, etc., may be with respect to a motor vehicle, such as a forward driving direction of a motor vehicle when the vehicle is operatively oriented on a normal driving surface. 
     Referring now to the drawings, wherein like reference numbers refer to like features throughout the several views, there is shown in  FIG. 1  a schematic illustration of a representative automobile, which is designated generally at  10  and portrayed herein for purposes of discussion as a passenger vehicle with a parallel P2 hybrid-electric powertrain. In particular, the illustrated powertrain is generally composed of a single engine  12  and a single motor  14  that operate, individually and in concert, to transmit tractive power to a multi-speed power transmission  16  through a hydrokinetic torque converter (TC) assembly  18  to drive one or more road wheels  20  of the vehicle&#39;s final drive system  11 . The illustrated automobile  10 —also referred to herein as “motor vehicle” or “vehicle” for short—is merely an exemplary application with which novel aspects and features of this disclosure can be practiced. In the same vein, implementation of the present concepts into a P2 hybrid powertrain architecture should also be appreciated as an exemplary application of the novel concepts disclosed herein. As such, it will be understood that aspects and features of the present disclosure can be applied to other vehicle powertrain configurations and utilized for any logically relevant type of motor vehicle. Lastly, only select components have been shown and will be described in additional detail herein. Nevertheless, the vehicles, powertrains, and disconnect devices discussed below can include numerous additional and alternative features, and other available peripheral components, e.g., for carrying out the various methods and functions of this disclosure. 
     The representative vehicle powertrain system is shown in  FIG. 1  with a prime mover, such as a restartable internal combustion engine (ICE) assembly  12 , that is drivingly connected to a driveshaft  15  of a final drive system  11  by a multi-speed automatic power transmission  16 . The engine  12  transfers power, preferably by way of torque via an engine crankshaft  13  (or “engine output member”), to an input side of the transmission  16 . According to the illustrated example, the ICE assembly  12  rotates an engine-driven torsional damper assembly  26  and, through the torsional damper assembly  26 , an engine disconnect device  28 , as will be described in further detail hereinbelow. This engine disconnect device  28 , when operatively engaged, transmits torque received from the ICE assembly  12  by way of the damper  26  to input structure of the TC assembly  18 . The transmission  16 , in turn, is adapted to receive, selectively manipulate, and distribute tractive power from the engine  12  to the vehicle&#39;s final drive system  11 —represented herein by a driveshaft  15 , rear differential  22 , and a pair of rear road wheels  20 —and thereby propel the hybrid vehicle  10 . The power transmission  16  and torque converter  18  of  FIG. 1  may share a common transmission oil pan or “sump”  32  for supply of hydraulic fluid, as well as a shared transmission pump  34  for sufficient hydraulic pressure to activate the elements of the transmission  16 , TC assembly  18 , and engine disconnect device  28 . 
     The ICE assembly  12  operates to propel the vehicle  10  independently of the electric traction motor  14 , e.g., in an “engine-only” operating mode, or in cooperation with the motor  14 , e.g., in a “motor-boost” operating mode. In the example depicted in  FIG. 1 , the ICE assembly  12  may be any available or hereafter developed engine, such as a compression-ignited diesel engine or a spark-ignited gasoline or flex-fuel engine, which is readily adapted to provide its available power output typically at a number of revolutions per minute (RPM). Although not explicitly portrayed in  FIG. 1 , it should be appreciated that the final drive system  11  may take on any available configuration, including front wheel drive (FWD) layouts, rear wheel drive (RWD) layouts, four-wheel drive (4WD) layouts, all-wheel drive (AWD) layouts, etc. 
       FIG. 1  also depicts an electric motor/generator unit  14  or other suitable traction motor that operatively connects via a motor support hub  29  (or “motor output member”) and torque converter  18  to an input shaft  17  (or “transmission input member”) of the transmission  16 . The motor/generator unit  14  may be directly coupled onto a TC input shaft or rigidly mounted to a housing portion of the torque converter  18 . The electric motor/generator unit  14  is composed of an annular stator  21  circumscribing and concentric with a rotor  23 . Electric power is provided to the stator  21  through electrical conductors or cables  27  that pass through the motor housing in suitable sealing and insulating feedthroughs (not illustrated). Conversely, electric power may be provided from the MGU  14  to an onboard traction battery pack  30 , e.g., through regenerative braking. Operation of any of the illustrated powertrain components may be governed by an onboard or remote vehicle controller, such as programmable electronic control unit (ECU)  25 . While shown as a P2 hybrid-electric architecture with a single motor in parallel power-flow communication with a single engine assembly, the vehicle  10  may employ other powertrain configurations, including PS, P1, P3, and P4 hybrid powertrains, any of which may be adapted for an HEV, PHEV, range-extended hybrid vehicle, fuel-cell hybrid vehicle, etc. 
     Power transmission  16  may use differential gearing  24  to achieve selectively variable torque and speed ratios between transmission input and output shafts  17  and  19 , respectively, e.g., while sending all or a fraction of its power through the variable elements. One form of differential gearing is the epicyclic planetary gear arrangement. Planetary gearing offers the advantage of compactness and different torque and speed ratios among all members of the planetary gearing subset. Traditionally, hydraulically actuated torque establishing devices, such as clutches and brakes (the term “clutch” used to reference both clutches and brakes), are selectively engageable to activate the aforementioned gear elements for establishing desired forward and reverse speed ratios between the transmission&#39;s input and output shafts. While envisioned as an 8-speed automatic transmission, the power transmission  16  may optionally take on other suitable configurations, including Continuously Variable Transmission (CVT) architectures, automated-manual transmissions, etc. 
     As indicated above, ECU  25  is constructed and programmed to govern, among other things, operation of the engine  12 , motor  14 , transmission  16 , TC  18 , and disconnect device  28 . Control module, module, controller, control unit, electronic control unit, processor, and any permutations thereof may be used interchangeably and synonymously to mean any one or various combinations of one or more of logic circuits, combinational logic circuit(s), Application Specific Integrated Circuit(s) (ASIC), electronic circuit(s), central processing unit(s) (e.g., microprocessor(s)), input/output circuit(s) and devices, appropriate signal conditioning and buffer circuitry, and other components to provide the described functionality, etc. Associated memory and storage (e.g., read only, programmable read only, random access, hard drive, tangible, etc.)), whether resident, remote or a combination of both, store processor-executable software and/or firmware programs or routines. Software, firmware, programs, instructions, routines, code, algorithms and similar terms may be used interchangeably and synonymously to mean any processor-executable instruction sets, including calibrations and look-up tables. The ECU  25  may be designed with a set of control routines executed to provide the desired functions. Control routines are executed, such as by a central processing unit, and are operable to monitor inputs from sensing devices and other networked control modules, and execute control and diagnostic routines to control operation of devices and actuators. Routines may be executed in real-time, continuously, systematically, sporadically and/or at regular intervals, for example, each 100 microseconds, 3.125, 6.25, 12.5, 25 and 100 milliseconds, etc., during vehicle use or operation. Alternatively, routines may be executed in response to occurrence of an event during operation of the vehicle  10 . 
     Hydrokinetic torque converter assembly  18  of  FIGS. 1 and 2  operates as a fluid coupling for operatively connecting the engine  12  and motor  14  with the internal epicyclic gearing  24  of the power transmission  16 . Disposed within an internal fluid chamber of the torque converter assembly  18  is a bladed impeller  36  juxtaposed with a bladed turbine  38 . The impeller  36  is situated in serial power-flow fluid communication with the turbine  38 , with a stator (not shown) interposed between the impeller  36  and turbine  38  to selectively alter fluid flow therebetween. The transfer of engine torque from the crankshaft  13  to the transmission  16  via the TC assembly  18  is through stirring excitation of hydraulic fluid, such as transmission oil, inside the TC&#39;s internal fluid chamber caused by rotation of the turbine and impeller blades. To protect these components, the torque converter assembly  18  is constructed with a TC pump housing, defined principally by a transmission-side pump shell  40  fixedly attached, e.g., via electron beam welding, MIG or MAG welding, laser welding, and the like, to an engine-side pump cover  42  such that a working hydraulic fluid chamber is formed therebetween. 
       FIG. 2  is an exploded, perspective-view illustration of select portions of the representative engine  12 , TC assembly  18 , torsional damper assembly  26 , and engine disconnect device  28 . Fundamentally, as the internal combustion engine  12  turns off to on, on to off, and operates at different rotational speeds during transient modes of powertrain operation, it may produce torque-related vibrations and oscillations (colloquially known as “torsionals”). By way of example, when fuel is being fed to the engine  12  and it is under power, e.g., through engagement of the fuel throttle (not shown herein) during normal operation, the engine  12  may produce torsionals that are undesirable to transmit to, and through, the transmission  16 . Moreover, when fuel is not being fed to the engine  12  or the feed of fuel is discontinued, e.g., the engine  12  is in a startup and/or a shutdown operation, the engine pistons may generate compression pulses. Both the torsionals and compression pulses can produce resultant vibrations, noise, and rattle that may be sensed by a vehicle occupant. To reduce or otherwise cancel out torsionals, torque swings, and compression pulses that may be produced by the engine  12 , the vehicle  10  is equipped with a torsional damper assembly  26  and an engine disconnect device  28 , as shown in  FIGS. 1-3 . As will be described in detail below, the damper assembly  26  and disconnect device  28  help to isolate the torque converter  18  and, thus, the transmission  12  from unwanted torsionals generated by the engine  12 , and also to selectively aide the motor/generator assembly  14  in canceling engine compression pulses during startup and shutdown operations. 
     According to the representative example illustrated in  FIGS. 2 and 3 , the engine disconnect device  28  is generally comprised of (from left-to-right in  FIG. 2 ): a selector plate  50 , a flex ring  52 , a reaction ring  54 , a negative (second) OWC  56 , and a positive (first) OWC  58 , all of which circumscribe a central hub  44  that is integrally formed with and projects from an exterior, engine-side surface of the pump cover  42 . In the same vein, the damper assembly  26  of  FIGS. 2 and 3  is generally comprised of a torsional damper plate  60  with one or more spring-mass damper systems (“SDS”)  62  that operatively attach the damper plate  60  to a flexplate  64 , all of which are supported on an engine hub  46  that is spline indexed to one end of the engine&#39;s crankshaft  13 . The selector plate  50  is shown sitting flush against the engine-side surface of the pump cover  42 , with the toroidal flex ring  52  compressed between the reaction ring  54  and selector plate  50 . Reaction ring  54  is bolted or otherwise rigidly mounted to the pump cover  42  for rotation in unison therewith. The negative and positive OWCs  56 ,  58  are sandwiched between the selector plate  50  and damper plate  60 , and both rotatably mounted onto the pump cover&#39;s central hub  44  around a thrust bearing  66  and Belleville washer  68  to rotate about axis A-A. As best seen in  FIG. 3 , the engine flexplate  64  is fabricated with a transmission-side cavity that nests therein the OWCs  56 ,  58  and damper plate  60 . Damper assembly  26  is interposed between the flexplate  64  and engine disconnect device  28 , with the flexplate  64  bolted directly to the engine hub  46  while the engine hub  46  is rotatably mounted onto the pump cover&#39;s central hub  44  via a high-speed needle bearing  70 . 
     With continuing reference to  FIG. 2 , the series of SDSs  62  mates the torsional damper plate  60  and the negative and positive OWCs  56 ,  58  with the engine flexplate  64  such that the damper plate  60  and a respective race of each OWC  56 ,  58  rotate in unison with the flexplate  64  while allotted restricted rotational movement therebetween. In accord with the illustrated example, the flexplate  64  is fabricated with eight (8) half-cylinder-shaped spring receptacles  72  that are circumferentially spaced in an equidistant manner about the flexplate&#39;s body. While it is envisioned that any logically relevant type of spring element may be employed, the SDS  62  of  FIG. 2  each includes a helical spring terminating at each end thereof with a spring retainer. Each SDS  62  is seated within a respective one of the spring receptacles  72  such that free lengths of the helical springs are elongated along the circumference of the flexplate  64 . The representative torsional damper plate  60  is integrally formed with eight (8) circumferentially spaced, L-shaped spring tabs  74  that are radially aligned with the spring receptacles  72  in the flexplate  64 . Each spring tab  74  projects into a gap between neighboring receptacles  72  and abuts a respective SDS  62 . When the flexplate  64  rotates under the driving power of the engine assembly  12 , the spring retainers of each SDS  62  are pressed against respective circumferentially spaced walls of the spring receptacles  72 , thereby compressing the springs of the SDS  62  against the spring tabs  74 . Once the SDS  62  are sufficiently compressed, torque from the crankshaft  13  is transmitted through the engine hub  46  and flexplate  64 , and transferred through the SDS  62  to the damper plate  60 . The allotted play between the damper plate  60  and flexplate  64  as governed by the SDS  62  helps to absorb and dampen unwanted torsionals produced by the engine  12  during startup, transient, and shutdown operations, as some non-limiting examples. 
     The vehicle powertrain is equipped with a “back-to-back” SOWC engine disconnect device  28  for drivingly connecting and disconnecting the ICE assembly  12  to/from the TC assembly  18  and, thus, the traction motor  14  and automatic transmission  16 . As will be explained in further detail below, use of two concentrically aligned OWCs  56 ,  58  that are arranged in parallel power flow communication with each other to carry forward (positive) torque and reverse (negative) torque in opposite directions helps to create a “backlash free” engine disconnect device. In addition, one or both of the OWCs  56 ,  58  may be selectively turned off, i.e., to freewheel in both directions, in order to improve engine-disconnected, motor-only driving. For configurations in which the negative OWC  56  is selectively disengageable, positive engine torque may be momentarily applied to unload the negative OWC  56  in order to ease clutch disengagement. The back-to-back SOWC engine disconnect device  28  also mitigates resultant noise during transient vehicle operation and helps to improve engine disconnect response time during coasting and motor-only operating modes. 
     With reference to  FIGS. 2-4 , the positive (first) OWC  58  functions to automatically operatively connect (or “lock”) the crankshaft  13  by way of engine hub  46  to the TC pump cover  42  when a speed ratio therebetween is at or above a preset threshold speed ratio (e.g., positive torque is being transferred at approximately 0.98:1.00). Conversely, the positive OWC  58  functions to automatically operatively disconnect (or “overrun”) the crankshaft  13  from the TC pump cover  42  when the speed ratio therebetween is below the aforementioned preset threshold speed ratio and/or when the torque reverses direction (e.g., to a negative torque). In the illustrated example, the positive OWC  58  includes a (first) annular inner race  76  that is concentrically aligned within a (first) annular outer race  78 . The outer race  78  is bolted, riveted, welded, and/or integrally formed with (collectively “rigidly attached”) the torsional damper plate  60  to rotate in unison therewith. Conversely, the inner race  76  is rigidly attached to the TC pump cover  42 , e.g., via L-shaped mounting tabs  71 , to rotate in unison therewith. Projecting axially and radially from the inner race  76 , these mounting tabs  71  are circumferentially spaced from one another around a TC-side face of the positive OWC&#39;s inner race  76 . Due to the large torque loads carried during forward driving, it may be desirable that the positive OWC  58  be larger than the negative OWC  56  such that the former circumscribes the latter, in accord with the illustrated example. It is envisioned, however, that the positive OWC  58  may be concentrically aligned within the negative OWC  56  for at least some powertrain applications. 
     Disposed between and selectively rotatably coupling the inner and outer races  76 ,  78  of the positive OWC  58  is a series of circumferentially spaced (first) torque transmitting elements  80 . These torque transmitting elements  80  (or “torque elements” for brevity) are illustrated as sixteen (16) identically shaped and sized cylindrical rollers; alternative configurations may incorporate any number, type, and combination of torque elements, including cylindrical rollers, tapered rollers, needle rollers, sprags, etc. Torque transmitting elements  80  are portrayed in  FIG. 4  as spring-biased rollers in which individual helical compression springs  82  ( FIG. 4 ) bias the illustrated rollers to a disengaged position. When disengaged, the torque transmitting rollers  80  are in an “unwedged” state to allow overrunning rotational motion of the outer race  78  relative to the inner race  76  in one direction (e.g., counterclockwise in  FIG. 4 ). A (first) roller cage  84 , which is interposed between the selector plate  50  and OWC  58 , includes axial projections  86  that press or otherwise “preload” the torque elements  80  to a “wedged” position and, concomitantly, an engaged state. In so doing, the two races  76 ,  78  are locked together to transmit (positive) torque from the flexplate  64  and torsional damper plate  60 , across the outer race  78  and rollers  82 , and through the inner race  76  to the TC pump cover  42 . 
     Negative OWC  56  functions to automatically operatively connect (or “lock”) the TC pump cover  42  to the engine hub  46  when torque is transmitted in the opposite direction from that of the positive OWC  58  and a corresponding speed ratio between the pump cover  42  and hub  46  is at or above a preset threshold speed ratio. On the other hand, the negative OWC  56  functions to automatically operatively disconnect (or “overrun”) the pump cover  42  from the hub  46  when the speed ratio therebetween is below the aforementioned preset threshold speed ratio and/or when the torque reverses back to the positive direction. Similar to the positive OWC  58 , the negative OWC  56  includes a (second) annular inner race  88  that is concentrically aligned within a (second) annular outer race  90 . Both annular races  88 ,  90  of the negative OWC  56  are disposed radially inside of and are mutually coaxial with both annular races  76 ,  78  of the positive OWC  58 . The negative OWC inner race  88  is bolted, riveted, welded, and/or integrally formed with the torsional damper plate  60  to rotate in unison therewith. Conversely, the negative OWC outer race  90  is operatively attached, e.g., via splined engagement, to the positive OWC inner race  76  to rotate in unison therewith. Through this engagement with the inner race  76 , outer race  90  is securely attached to the TC pump cover  42  to rotate in unison therewith. 
     A series of circumferentially spaced (second) torque transmitting elements  92  is disposed between and rotatably couples the inner and outer races  88 ,  90  of the negative OWC  56 . These torque transmitting elements  92  (also referred to herein as “torque elements” for brevity) are illustrated in  FIGS. 2 and 4  as five (5) identically shaped and sized cylindrical rollers. It is desirable, for at least some applications, that both OWCs  56 ,  58  employ roller-type torque transmitting elements. However, torque elements  80 ,  92  may take on any structure suitable for transmitting torque between complementary races of a one-way clutching device. Torque transmitting elements  92  are portrayed in  FIG. 4  as spring-biased torque elements in which individual helical compression springs  94  ( FIG. 4 ) bias the illustrated rollers  92  to a disengaged position. When disengaged, the rollers  92  are in an “unwedged” state to allow overrunning rotational motion of the inner race  88  relative to the outer race  90  in one direction (e.g., clockwise in  FIG. 4 ). A (second) roller cage  96 , which is interposed between the selector plate  50  and OWC  56 , includes axial projections  98  that press or otherwise “preload” the torque elements  92  to a “wedged” position and, concomitantly, a torque-transmitting engaged state. In so doing, the two races  88 ,  90  are locked together to transmit (negative) torque from the pump cover  42  of the TC assembly  18 , across the negative OWC outer race  90  and rollers  92 , and through the inner race  88  to the torsional damper plate  60 . 
     Selector plate  50  may be selectively actuable, e.g., via ECU  25  responsive to a transient vehicle operation, to move back-and-forth along a rectilinear path to transition between deactivated and activated states. When activated, this selector plate  50  switches one or both OWCs  56 ,  58  from a torque-carrying (locked) state to a non-torque-carrying (freewheeling) state. Conversely, deactivating the selector plate  50  will switch one or both of the OWCs  56 ,  58  from a non-torque-carrying state to a torque-carrying state. In accord with the illustrated example, selector plate  50  slides axially, e.g., from left-to-right in  FIGS. 2 and 3  on a path parallel to axis A-A, from a deactivated state to an activated state. The deactivated selector plate  50  seats flush against the TC pump cover  42  and operatively disengages the roller cage  96 . Activating the selector plate  50  displaces it away from the pump cover  42  such that the plate  50  rotates the negative OWC roller cage  96  from an engaged state to a disengaged state. Rotating the roller cage  96  in this manner disengages the axial projections  98  from the torque transmitting rollers  92  and concomitantly frees these torque elements  92  to shift to non-torque-transmitting positions under the biasing forces of compression springs  94 . 
     To convert the translational motion of the selector plate  50  into the rotational motion of the roller cage  96 , the representative selector plate  50  is integrally formed with or otherwise fabricated to include a series of ramped shanks  100  (see inset view of  FIG. 4 ). These ramped shanks  100  are circumferentially spaced in an equidistant manner about, and project axially from the selector plate&#39;s engine-side surface. The negative OWC&#39;s roller cage  96  is formed with a series of circumferentially spaced windows  102 , each of which is shaped, sized and located to receive therethrough a respective one of the ramped shanks  100 . Sliding the selector plate  50  from the deactivated position to the activated position will contemporaneously slide each ramped shank  100  against the inner perimeter of its corresponding window  102 . The axially angled contact surfaces of the shanks  100  apply a moment force to the roller cage  96  via windows  102  to rotate the roller cage  96  to the disengaged state. Shifting the select plate  50  back to the deactivated position, as described below, will operatively disengage the ramped shanks  100  from the windows  102 , allowing the roller cage  96  to rotate back to the engaged state and, thus, push the torque elements  92  to their wedged positions. 
     Back-to-back SOWC engine disconnect device  28  employs hydraulically actuated, spring-loaded pistons  104  (one of which is shown in  FIG. 3 ) to move the selector plate  50  to the activated state. According to the illustrated example, five (5) spring-loaded pistons  104  are circumferentially spaced in an equidistant manner around the pump cover  42  of the TC assembly  18 . As shown, each piston  104  is slidably mounted in a sealing fashion to TC assembly  18 , passing at least partially through the pump cover  42 . When the hydraulic pressure inside the internal fluid chamber of the TC assembly  18  exceeds the spring force of return springs  106 , the pistons  104  stroke, e.g., left-to-right in  FIG. 2 , and push the selector plate  50  from the deactivated state to the activated state. When this internal hydraulic pressure is relieved, return springs  106  bias the pistons to a deactuated position; at the same time, toroidal flex ring  52  presses against and biases the selector plate  50  to the deactivated state. Annular reaction ring  54 , which circumscribes the selector plate  50  and flex ring  52 , provides a reaction surface against which the flex ring  52  presses. 
     Another representative engine disconnect device  128  is presented in  FIG. 5  and portrayed for purposes of discussion as a positive-engagement, pawl-type SOWC assembly. Although differing in appearance, it is envisioned that any of the features and options set forth above with reference to the engines, torque converters, damper assemblies and disconnect devices of  FIGS. 1-4  can be incorporated, singly or in any combination, into the corresponding components discussed below with respect to  FIGS. 5-14 , and vice versa. Similar to the torque converter  18  of  FIGS. 1 and 2 , for example, the TC assembly  118  of  FIG. 5  is a hydrodynamic engine-to-transmission drive coupling that includes a TC pump housing, which may generally comprise a transmission-side pump shell  140  that is fixedly attached to an engine-side pump cover  142  such that a working hydraulic fluid chamber is formed therebetween. As another example, an engine hub  146  of  FIG. 5  is spline indexed to one end of an engine output shaft, such as crankshaft  13  of  FIGS. 1 and 2 , with an axially-flexible engine flexplate  166  bolted directly to the engine hub  146 . 
     Engine disconnect device  128  of  FIG. 5  includes an annular pocket plate  160  that is fabricated with a succession of circumferentially spaced pockets  163  ( FIGS. 6-8 ). These pockets  163  may have an elongated, polyhedral shape, each of which is recessed into a transmission-side surface of the pocket plate  160 . Each pocket  163  is shaped and sized to receive therein a respective torque-transmitting engaging element  170 A,  170 B ( FIGS. 6-8 ) that functions to engage a pocket  163  of the pocket plate  160  with a notch  192  in a notch plate  190 . In the illustrated example, the notch plate  190  is integrally formed as a single-piece structure with the pump cover  142  of the torque converter  118 ; alternative designs may include a notch plate  190  that is formed as a separate part that is subsequently mounted onto and drivingly connected with the TC assembly  118 . When the engaging elements  170 A,  170 B project into and abut both the pockets  163  and notches  192 , as seen in  FIG. 8 , they cooperatively lock the pocket plate  160  to the notch plate  190  such that the two rotate in unison in both forward and reverse directions. Conversely, when one set of engaging elements  170 A—represented herein as negative-torque-transmitting pawls—are withdrawn into their respective notches  192 A, as seen in  FIG. 6 , the pocket plate  160  is allowed to rotate with respect to the notch plate  190  in one direction (rightward in  FIG. 6 ). 
     According to the representative architecture of  FIGS. 5-8 , each engaging element  170 A,  170 B is composed of a spring-biased pawl that is rotatably seated within a respective one of the aforementioned notches  192 A,  192 B. These pawls may have a generally rectangular plan profile with beveled engaging ends. It is also envisioned that the engaging element  170 A,  170 B take on other forms, including sprags, struts, etc. Each pawl  170 A,  170 B is provided with a dedicated biasing member  172 , which may be a torsion spring, a coil spring, a constant force spring, or any other element capable of providing lift to one end of a torque-transmitting engaging element. While shown mounted within the notches  192  of the notch plate  190 , it is envisioned that the engaging element  170 A,  170 B may be similarly packaged within the pockets  163  of the pocket plate  160 . 
     With reference again to  FIG. 5 , the notch plate  190  may generally consist of circumferentially spaced notches  192  that are individually recessed into the engine-side surface of the front pump cover&#39;s flange portion  133 . This series of notches  192  is radially aligned with the pockets  163  in the pocket plate  160 , each shaped and sized to receive therein a pawl  170 A,  170 B. Distal ends of the pawls  170 A,  170 B engage the pockets  163 —thereby locking the pocket plate  160  to the pump cover  142  for common rotation therewith—by protruding forward into (e.g., to the right in  FIG. 5 ) and pressing against the pockets  163 . Conversely, one or both sets of the pawls  170 A,  170 B may selectively disengage from the pocket plate  160 —thereby unlocking the pocket plate  160  from the pump cover  142  to freewheel thereon—by receding into their respective notches  192  out of contact with the pockets  163 . It will be apparent that the number, arrangement, and geometry of the engaging elements  170 A,  170 B, including their corresponding pockets  163  and notches  192 , can be varied from that which are shown in the drawings depending, for example, on design requirements for the intended application. 
     To govern the operating status of the engine disconnect device  128  and, thus, the torque-transmitting mechanical coupling between the engine assembly  112  and torque converter  118 , the disconnect device  128  is provided with a selector plate  162  and selector ring  164  that cooperatively control the engagement and disengagement of one or both sets of pawls  170 A,  170 B. Selector plate  162  is a disk-shaped annulus that neighbors the pocket plate  160  and is coaxially aligned with the torque converter  118  and damper assembly  126  to rotate about axis A-A of  FIG. 5 . As shown, the selector plate  162  is mounted for rotational movement relative to the pocket and notch plates  160 ,  190  to transition back-and-forth between engaged and disengaged positions. When the selector plate  162  is in its engaged position, as best seen in  FIG. 8 , both sets of engaging elements  170 A,  170 B are allowed to shift into engagement with the notches  192  of the notch plate  190 , e.g., under the biasing force of the biasing members  172 . By way of example, and not limitation, the selector plate  162  is machined with a series of circumferentially spaced windows  165 , each of which is shaped and sized to receive therethrough a portion of a single pawl  170 A,  170 B. Moving the selector plate  162  to the engaged position aligns the windows  165  with corresponding notches  192  such that the pawls  170 A,  170 B seated therein project through the windows  165  and into the pockets  163  of the pocket plate  160 . On the other hand, when the selector plate  162  rotates (e.g., counterclockwise in  FIG. 5 ) to its disengaged position, as best seen in  FIG. 6 , the plate  162  shifts the negative-torque-transmitting engaging elements  170 A out of engagement with the pocket plate  160 . 
     The selector ring  164  of  FIG. 5  is a disc-shaped component with a centrally located cylindrical hub  167  that is sized to circumscribe and seat therein the SOWC pocket plate  160 . When the engine disconnect device  128  is fully assembled, an aft-facing, transmission-side surface of the selector ring  164  sits generally flush against a forward-facing, engine-side surface of the selector plate  162 , while an inner-diameter surface of the central hub  167  sits generally flush with an outer periphery surface of the pocket plate  160 . Circumferentially spaced tabs  169  project from the selector plate  162  into complementary slots in the selector ring  164  to operatively interconnect the two components such that they rotate in unison with each other. A selectively engageable brake mechanism (not shown) is activated by a vehicle controller, such as ECU  25  of  FIG. 1 , to restrict rotational motion of the selector ring  164  about axis A-A. In so doing, the ring  164  is selectively transitioned back-and-forth from between deactivated and activated positions to thereby move the selector plate  162  between the engaged and disengaged positions, respectively. 
     With continuing reference to  FIG. 5 , the engine flexplate  166  is located immediately adjacent and sandwiched between the pocket and damper plates  160 ,  168 . Flexplate  166  mechanically attaches the damper assembly  126  and, indirectly, the engine disconnect device  128  to the torque-transmitting output of the engine assembly  112 . Machined into the flexplate  166  is a circular array of circumferentially spaced fastener holes  171 . As seen in  FIG. 5 , these fastener holes  171  receive therethrough threaded bolts  178  or other suitable fasteners that threadably mate with complementary internally threaded female holes in the engine hub  146  to thereby rigidly couple the flexplate  166  directly to the engine hub  146  to rotate in unison with the engine output shaft. Flexplate  166  drivingly connects the damper assembly  126 , disconnect device  128  and, when desired, the torque converter assembly  118  to the engine  112 —by way of engine hub  146 —such that rotational power is transferable back-and-forth therebetween. In addition to operating to transmit torque produced by the engine  112  to the transmission (e.g., transmission  16  of  FIG. 1 ), the flexplate  166  may also function to absorb thrust loads that may be generated by the engine&#39;s reciprocating pistons and/or the torque converter&#39;s hydrodynamic activities. Projecting radially outward from an outer diameter (OD) edge of the flexplate body is a succession of gear teeth  173 —collectively defining a “starter ring gear”—that operatively engage with gear teeth of an engine starter. 
     A ring-shaped damper plate  168 , which sits generally flush against an engine-side surface of the flexplate  166 , circumscribed by the starter ring gear teeth  173 , is fixedly attached, e.g., via hexagonal bolts  180  or other suitable fasteners, to the pocket plate  160  for common rotation therewith. In any of the instances in this disclosure where bolts or threaded fasteners are disclosed as a mechanism for connecting two or more components, it should be recognized that other processes may be employed to join those components, such as riveting, welding, forming, etc. Damper plate  168  is shown interposed between and, thus, sandwiched by the engine assembly  112  and the flexplate  166 . The damper plate  168  of  FIGS. 2 and 3  is also equipped with one or more spring-mass damper systems, also referred to herein as “SDS” and identified as  182  in the drawings. These SDS  182  are shown spaced circumferentially around and positioned proximate to the outer periphery of the damper plate  168 . 
     The SDS  182  mate the damper plate  168  and pocket plate  160  with the flexplate  166  such that the pocket and damper plates  160 ,  168  are movably attached to the flexplate  166 . In accord with the illustrated example, the damper plate  168  is fabricated with half-cylinder-shaped spring receptacles  175  that are equidistantly spaced about the damper plate&#39;s circumference. While it is envisioned that any logically relevant type of spring element may be employed, the SDS  182  of  FIG. 5  each includes a helical spring terminating at each end thereof with a spring retainer. Each SDS  182  seats within a respective one of the spring receptacles  175  such that the length of each helical spring is elongated along the circumference of the plate  168 . Defined through the body of the flexplate  166  are circumferentially spaced spring windows  177 , each of which receives therethrough a respective one of the SDS helical springs. To this regard, the pocket plate  160  is formed with circumferentially spaced spring channels  179  that correspond in number and are radially aligned with the spring windows  177  in the flexplate  166  and the spring receptacles  175  in the damper plate  168 . With this arrangement, the helical springs of the SDS  182  nest within the channels  179 , sandwiched between the pocket and damper plates  160 ,  168 . When the flexplate  166  rotates under the driving power of the engine assembly  112 , the spring retainers of each SDS  182  are pressed against respective circumferentially spaced walls of the spring windows  177 , thereby compressing the springs. This interaction can be used to absorb and dampen unwanted torsionals produced by the engine  112  during normal, startup, transient and shutdown operations, as some non-limiting examples. 
     Turning next to  FIG. 6 , the SOWC notch plate  190  of disconnect device  128  is shown with multiple “floating” notch plate inserts  120  that are nested within some or all of the notches  192  and supporting thereon some or all of the pawls  170 A,  170 B. In accord with the illustrated example, the notch plate insert  120  may be integrally formed as a unitary, single-piece structure with a base  121  and a ramped wall  123  projecting from one end of the base  121 . An inboard facing, transmission-side surface of the base  121  slides against an outboard-facing, engine-side surface of a discrete notch  192 A. Conversely, an outboard surface of the base  121  provides subjacent support for a negative-torque-carrying pawl  170 A and its corresponding bias spring  172 . Acting as a pivot point, a fixed, proximal end of the pawl  170 A abuts the base  121  of the notch plate insert  120 ; the spring  172  operates to bias a moving, distal end of the pawl  170 A to pivot away from the base  121 , through the selector plate  162 , and into the pocket plate  160 . For embodiments in which notch plate inserts  120  are only provided for select engaging elements (e.g., only the negative-torque carrying pawls  170 A in  FIGS. 6-8 ), the notches  192 A for those select pawls  170 A may be larger in depth, width, and/or length than their counterpart notches  192 B for the positive-torque carrying pawls  170 B to provide additional packaging space for the notch plate inserts  120 . In this regard, the pawls  170 A may be slightly shorter in length than the pawls  170 B to accommodate the notch plate inserts  120 . 
     Reciprocally mounted within each of the notches  192 A of  FIGS. 6-8 , adjacent the notch plate inserts  120  and the pawls  170 A borne thereby, is a spring-biased wedge insert  122 . While an assortment of shapes and sizes are envisioned, these wedge inserts  122  are shown as unitary, single-piece structures with a non-regular polygonal cross-section. Wedge springs  124  are also mounted within the notches  192 A, each of which is sandwiched between the notch plate  190  and an individual wedge insert  122 . Portrayed in a representative example as helical compression springs, these wedge springs  124  bias the wedge inserts  122  axially out of their respective notches  192 A (e.g., upward in  FIGS. 6-8 ; rightward in  FIG. 5 ). Each wedge insert  122  includes a ramped surface  125  that abuts and sits generally flush against the ramped wall  123  of the notch plate insert  120 . As seen in  FIG. 6 , both the ramped wall  123  and ramped surface  125  are obliquely angled with respect to the outboard-facing notch surface against which is seated and slides the notch plate insert  120 . Each wedge insert  122  is also fabricated with a ramped engine-side face  127  that adjoins and is obliquely angled with respect to the ramped surface  125 . Complementary to the ramped faces  127  of the inserts  122  are ramped edges  161  located along trailing sides of the selector plate windows  165 . As will be explained further below, movement of the selector plate  162  to the engaged (second) position will slide the ramped edges  161  of the selector plate windows  165  against the ramped faces  127  of the wedge inserts  122 . Angling the points of contact between the wedge inserts  122  and selector plate  162 —edges  161  and faces  127  of  FIG. 6  are obliquely angled with respect to the trajectory of the moving selector plate  162 —will generate a generally axial force vector that projects inboard and pushes the wedge inserts  122  axially into the notches  192 A. 
     In the sequence of illustrations presented in  FIGS. 6-8 , the notch plate inserts  120  slide left-to-right, and back again, between a vacating location (e.g., a first, rightmost position in  FIG. 6 ) and a filling location (e.g., a second, leftmost position in  FIG. 8 ) to take-up any backlash space within the notches  192  during engagement of the pawls  170 A. As indicated above, the selector plate  162  rotates back-and-forth about axis A-A between a disengaged position—shifting the engaging elements  170 A out of engagement with the pockets  163  ( FIG. 6 )—and an engaged position—allowing the engaging elements  170 A to shift into engagement between the pockets  163  and notches  192 A ( FIG. 8 ). When moved to the engaged position (e.g., to the left in  FIG. 7 ), the selector plate  162  concomitantly presses the wedge inserts  122  (e.g., downward in  FIG. 7 ) against the notch plate inserts  120 . As the force applied by the selector plate  162  to the wedge inserts  122 , e.g., via ramped window edges  161  sliding against ramped insert faces  127 , overcomes the bias force of the wedge springs  124 , the wedge inserts  122  translate along a generally rectilinear path that is orthogonal to the path of the selector plate. As a result, the wedge inserts  122  slide their respective ramped surfaces  125  against the ramped walls  123  of their corresponding notch plate insert  120 . This force, in turn, pushes the notch plate inserts  120  along a generally rectilinear, yet circumferential path with respect to the notch plate  190  to the backlash-space filling (second) location in  FIG. 8 . It may be desirable, for at least some embodiments, that the wedge inserts  122  slide, e.g., up-and-down in  FIGS. 6-8 , against an adjacent end wall of the notch  192 . 
       FIG. 10  illustrates a representative hydraulic control circuit  200  for activating and deactivating both a representative torque converter clutch (TCC) assembly  202  of a TC assembly  218  and a representative selectable one-way engine disconnect clutch (EDC) assembly  228  using apply-side and release-side pressures of the TCC assembly  202 . Hydraulic control circuit  200  utilizes a solenoid-actuated torque converter and transmission (TCT) valve assembly  250  that is designed to use an absolute apply pressure of a TCC circuit to control the selective engagement and disengagement of the EDC assembly  228 , while a relative pressure between a TCC apply pressure and a TCC release pressure controls the selective engagement and disengagement of the TCC assembly  202 . The hydraulic control circuit  200  allows for control of both the TCC and EDC assemblies  202 ,  228  using a TC feed circuit  252  and a TCC feed circuit  254  without utilizing additional pressurized hydraulic circuits and attendant hardware dedicated to governing the EDC assembly  228 . 
     As a point of reference during the discussion of the hydraulic circuit architecture of  FIG. 10 ,  FIG. 9  presents a graph  300  of hydraulic pressure (kilopascals (kPa)) versus time (milliseconds (ms)) for the internal fluid chamber  204  of the TC assembly  218 . A first plot  302  in graph  300  is indicative of TCC apply pressure on the TCC assembly  202 , namely a measured hydraulic pressure on an apply face  205  of a TCC friction plate  206  that is facing a turbine shell  208  of the TC assembly  218 . Likewise, a second plot  304  in graph  300  of  FIG. 9  is indicative of TCC release pressure on the TCC assembly  202 , namely a measured hydraulic pressure on a release face  207  of the TCC friction plate  206  that is facing the pump cover of the TC assembly  218 . While the TC assembly  218  is provided purely as a representative application of the concepts presented in  FIGS. 9-11 , the twin-faced TCC friction plate  206  in the inset view of  FIG. 10  may be desirable for increased clutch gain. Moreover, it should be appreciated that the graph  300  is provided purely for purposes of clarification, and is therefore non-limiting in nature. 
     From an initiation time marker to t 0  a first time marker t 1 , a first pressure difference P D1  between the TCC apply and release pressures  302 ,  304  is roughly equal to a calibrated activation pressure differential such that the TCC assembly  202  carries torque, but is at or beyond a threshold of “slipping.” For this same timeframe, the EDC assembly  228  may be under positive power while the control system slips the TCC assembly  202 . The EDC assembly  228  may be normally engaged to enable the transfer of torque in both positive and negative directions and, thus, facilitate motor-assisted engine starts using an electric traction motor, such as MGU  14  of  FIG. 1 . Subsequent to second time marker t 2 , i.e., during the transition from t 1  to third time marker t 3 , an absolute value of the TCC release pressure  304  achieves a first calibrated pressure threshold P T1  (e.g., 700 kPa); at this pressure the EDC assembly  228  is disengaged or “opened” such that torque is transferable, e.g., in only a single (positive) direction. At time t 3 , there remains sufficient pressure difference across the TCC assembly  202  so that it continues to carry torque. 
     The absolute value of the TCC apply pressure  302  has reached a second calibrated pressure threshold P T2  (e.g., 900 kPa) at time marker t 3 . At this juncture, the TCC assembly  202  has adequate torque carrying capacity to carry a predetermined minimum torque (e.g., 150 Newton-meters (Nm)); the EDC assembly  228  remains open from time marker t 3  to t 4 , e.g., to facilitate motor-only “EV driving.” An optional auxiliary pump (not shown) may be included to enable motor-only, EV driving from zero vehicle speed. At a fourth time marker t 4 , the relative pressure between the TCC apply and release pressures  302 ,  304  drops to zero. As a result, the TCC assembly  202  is slipped and opens such that the TC assembly  218  unlocks, e.g., in preparation for an engine reconnect operation. Charge pressure is thereafter released to bring the absolute value of the TCC apply pressure  302  down below the first calibrated pressure threshold P T1  at a fifth time marker t 5 . In so doing, the EDC assembly  228  is reengaged to carry torque in opposing forward and reverse directions. 
     Turning back to the hydraulic control circuit  200  of  FIG. 10 , the TC feed circuit  252  includes a spring-biased, hydraulically-actuated line pressure regulator valve  256  that is fluidly coupled via a TC feed line  251  to a spring-biased, hydraulically-actuated TCC control valve  258  of the TCC feed circuit  254 . Line pressure regulator valve  256  is fluidly downstream from and connected to the TCT valve assembly  250  via blowoff line  253 . This blowoff line  253  also fluidly connects the line pressure regulator valve  256  and TCT valve assembly  250  to a pump (line pressure) “blowoff” ball valve  260 . In this regard, TCC control valve  258  is fluidly upstream from and connected to the TCT valve  250  via exhaust line  255 . A TCC release line  257  fluidly connects the TCC control valve  258  to a TCC “blowoff” ball valve  262  and to the release side of the TCC assembly  202 . During system operation, valve assembly  250  may be opened at time t 1  and controlled to provide regulated pressure to the release circuit through time t 5 . Once the torque converter is fully opened at time t 1  and charge pressure is lowered to normal levels, the TCC control valve  258  may be switched such that the valve  250  is bypassed and the torque converter transitions into an “open” mode. 
     Activation of the line pressure regulator valve  256  is controlled, in part, via feeds of hydraulic fluid received from a pressure control solenoid (PCS) line  259  and from the blowoff line  253 . In this regard, activation of the TCC control valve  258  is controlled, in part, via feeds of hydraulic fluid received from a TCC apply line  261  and the TC feed line  251 . TCC apply line  261  also fluidly connects the TCC control valve  258  to the apply side of the TCC assembly  202 . First and second normally-off pressure control solenoids  264  and  266 , respectively, govern hydraulic pressure in an actuator feed limiting line  263 . The line pressure regulator valve  256  is also provided with a suction line  267  and an exhaust port  269 . In addition, TCC control valve  258  is provided with a cooler feed line  271  and an exhaust port  273 . 
     With continuing reference to  FIG. 10 , the TCT valve assembly  250  includes a valve stem  268  that is slidably mounted inside a valve body  270  and is biased at one end thereof by a helical valve spring  272  or similarly suitable biasing member. At the opposite end of the valve body  270  from the valve spring  272  is an electronic linear-force (LFS) solenoid  274  that operates as a direct electric shift control for the valve stem  268 . The valve body  270  is also provided with three exhaust ports: a first exhaust port  275  at a distal end of the valve body  270  inline with a spring chamber within which is packaged the valve spring  272 ; a second exhaust port  277  interposed between first and second release ports  281  and  283 , respectively, of the valve body  270 ; and a third exhaust port  279  at a proximal end of the valve body  270 , opposite the first exhaust port  275 , and inline with a solenoid chamber of the LFS solenoid  274 . The first release port  281  is interposed between the first and second exhaust ports  275 ,  277  relative to the valve body  270 , whereas the second release port  283  is interposed between the second and third exhaust ports  277 ,  279  relative to the valve body  270 . A blowoff line port  285  is inline with the second release port  283  and, thus, interposed between the second and third exhaust ports  277 ,  279  relative to the valve body  270 . 
     Rectilinear movement of the valve stem  268  between longitudinal ends of the valve body  270  will govern the transfer of hydraulic fluid received from the TCC control valve  258 , through the exhaust line  255 , and into the valve body  270  via first and second release ports  281 ,  283 . Valve stem  268  movement also governs the transfer of hydraulic fluid from the second release port  283 , through the valve body  270 , out the blowoff line port  285  and to the line pressure regulator valve  256  via blowoff line  253 . The TCT valve assembly  250  is activated by the TCC mode control valve  258 . When the torque converter is in a “closed” configuration, the valve assembly  250  may be activated and selectively used to open or close both the TCC and EDCs. 
     With reference now to the flowchart of  FIG. 11 , an improved method or control strategy for governing operation of a torque converter clutch, such as TCC assembly  202  of TC assembly  218  of  FIG. 10 , and an engine disconnect device, such as EDC assembly  228  of ICE assembly  212  of  FIG. 10 , is generally described at  400  in accordance with aspects of the present disclosure. Some or all of the operations illustrated in  FIG. 11  and described in further detail below may be representative of an algorithm that corresponds to processor-executable instructions that may be stored, for example, in main or auxiliary or remote memory, and executed, for example, by a resident or remote controller, processing unit, control logic circuit, or other module, device and/or network of devices, to perform any or all of the above or below described functions associated with the disclosed concepts. It should be recognized that the order of execution of the illustrated operation blocks may be changed, additional blocks may be added, and some of the blocks described may be modified, combined, or eliminated. 
     Method  400  begins at terminal block  401  of  FIG. 11  with processor-executable instructions for a programmable controller or control module or similarly suitable processor to call up an initialization procedure for a TCC/EDC control protocol. This routine may be executed in real-time, continuously, systematically, sporadically, and/or at regular intervals during active vehicle operation. To carry out this protocol, a vehicle control system or any combination of one or more subsystems may be operable to receive, process, and synthesize pertinent information and inputs, and execute control logic and algorithms to regulate various powertrain components to achieve desired control targets. At input/output block  403 , the method  400  includes receiving one or more electrical signals indicating a sensor measured value for a TCC apply pressure and a sensor measured value for a TCC release pressure. 
     At decision block  405 , the method  400  determines if a real-time pressure difference between the TCC apply and release pressures is less than a calibrated activation pressure differential. If the vehicle ECU  25  or powertrain control module (PCM) not detects that the pressure difference exceeds the calibrated activation pressure differential (Block  405 =NO), the method  400  proceeds to process block  407  and outputs one or more control command signals, e.g., to hydraulic control circuit  200  of  FIG. 10 , to slip the TCC and maintain the EDC in a bi-directionally engaged state. If, however, a positive determination is returned (Block  405 =YES), the method  400  proceeds to process block  409  and outputs one or more control command signals, e.g., to hydraulic control circuit  200 , to close the TCC and thereby mechanically lock the TC impeller at the output of the engine to the TC turbine at the input of the transmission. 
     Prior to, contemporaneous with, or after executing the determination and corresponding operations of blocks  405 ,  407  and  409 , the method  400  determines, at decision block  411 , whether or not the TCC apply pressure is greater than a calibrated pressure threshold. If so (Block  411 =YES), method  400  proceeds to process block  413  and outputs one or more control command signals, e.g., to hydraulic control circuit  200  of  FIG. 10 , to disengage the EDC to operate in a unidirectional OWC state. The EDC may be disengaged while the TCC is maintained in a slipping state. However, if it is determined that the TCC apply pressure is below or falls below the calibrated pressure threshold (Block  411 =NO), method  400  proceeds to process block  415  and outputs one or more control command signals, e.g., to hydraulic control circuit  200 , to engage or maintain the EDC in an engaged state. As described above with respect to the graph of  FIG. 9 , the TCC may be engaged after the ECD is opened; optionally, the TCC may be opened prior to reengaging the ECD. The method  400  continues to terminal block  417  and temporarily terminates or returns to terminal block  401  and persists in a continuous loop. 
     Aspects of this disclosure may be implemented, in some embodiments, through a computer-executable program of instructions, such as program modules, generally referred to as software applications or application programs executed by any of a controller or the controller variations described herein. Software may include, in non-limiting examples, routines, programs, objects, components, and data structures that perform particular tasks or implement particular data types. The software may form an interface to allow a computer to react according to a source of input. The software may also cooperate with other code segments to initiate a variety of tasks in response to data received in conjunction with the source of the received data. The software may be stored on any of a variety of memory media, such as CD-ROM, magnetic disk, bubble memory, and semiconductor memory (e.g., various types of RAM or ROM). 
     Moreover, aspects of the present disclosure may be practiced with a variety of computer-system and computer-network configurations, including multiprocessor systems, microprocessor-based or programmable-consumer electronics, minicomputers, mainframe computers, and the like. In addition, aspects of the present disclosure may be practiced in distributed-computing environments where tasks are performed by resident and remote-processing devices that are linked through a communications network. In a distributed-computing environment, program modules may be located in both local and remote computer-storage media including memory storage devices. Aspects of the present disclosure may therefore be implemented in connection with various hardware, software or a combination thereof, in a computer system or other processing system. 
     Any of the methods described herein may include machine readable instructions for execution by: (a) a processor, (b) a controller, and/or (c) any other suitable processing device. Any algorithm, software, control logic, protocol or method disclosed herein may be embodied as software stored on a tangible medium such as, for example, a flash memory, a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), or other memory devices. The entire algorithm, control logic, protocol, or method, and/or parts thereof, may alternatively be executed by a device other than a controller and/or embodied in firmware or dedicated hardware in an available manner (e.g., implemented by an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable logic device (FPLD), discrete logic, etc.). Further, although specific algorithms are described with reference to flowcharts depicted herein, many other methods for implementing the example machine-readable instructions may alternatively be used. 
       FIGS. 12 and 13  of the drawings illustrate two more representative engine disconnect devices  528  and  628 , respectively, for drivingly connecting and disconnecting an internal combustion engine to/from a vehicle drivetrain. As mentioned above in the discussion of engine disconnect device  128  of  FIG. 5 , it is envisioned that any of the features and options set forth above with reference to the concepts presented in  FIGS. 1-11  can be incorporated, singly or in any combination, into the exemplary architectures discussed below with respect to  FIGS. 12 and 13 , and vice versa. Similar to the torque converters  18  and  118  of  FIGS. 2 and 5 , for example, the TC assemblies  518  and  618  of  FIGS. 12 and 13  are hydrodynamic torque transmitting devices that provide a drive coupling between the engine and transmission. TC assemblies  518 ,  618  both include a transmission-side pump shell  540 ,  640  that is fixedly attached to an engine-side pump cover  542 ,  642  such that a working hydraulic fluid chamber is formed therebetween. Akin to engine hubs  46  and  146  of  FIGS. 2 and 5 , each engine hub  546  and  646  of  FIGS. 12 and 13  is spline indexed to an engine output shaft, such as crankshaft  13  of  FIG. 1 , with an axially-flexible engine flexplate  566  and  666  bolted directly to the engine hub  546 ,  646 . 
     According to the illustrated architectures of  FIGS. 12 and 13 , engine disconnect devices  528 ,  628  are portrayed as wedge-type SOWC assemblies with radially displaceable locking elements. In line with the representative design in  FIG. 12 , for example, the engine disconnect device  528  is generally comprised of (from left-to-right): a selector plate  550 , a flex ring  552 , a reaction ring  554 , and a wedge-type SOWC  556 . The foregoing elements circumscribe and are directly or indirectly supported on a central hub  544 , which is integrally formed with and projects axially from an exterior, engine-side surface of the pump cover  542 . Similar to the torsional damper assembly  26  of  FIG. 2 , a torsional damper assembly  526  of  FIG. 12  is generally comprised of a torsional damper plate  560  with one or more spring-mass damper systems (“SDS”)  562  that operatively attach the damper plate  560  to the engine flexplate  56 . The damper plate  560 , SDS  562  and flexplate  56  are all supported by the engine hub  546 , which is rigidly secured to the crankshaft of engine  512  to rotate in unison therewith. 
     The selector plate  550  of  FIG. 12  may be structurally similar to the selector plate  50  of  FIG. 2  and therefore may function in an analogous manner to selectively switch the operating state of the engine disconnect device  528 . Selector plate  550 , when deactivated, may sit flush against the engine-side surface of the pump cover  542 , with the toroidal flex ring  552  compressed between the reaction ring  554  and selector plate  550 . Reaction ring  554  is bolted or otherwise rigidly mounted to the pump cover  542  to rotate in unison therewith. Projecting radially outward from an OD perimeter of the reaction ring  554  is a succession of integrally formed ring gear teeth  573  that operatively engage with gear teeth of a motor generator unit, such as the traction motor  14  of  FIG. 1 . Shown sandwiched between the selector plate  550  and damper plate  560 , wedge-type SOWC  556  is rotatably mounted onto the pump cover&#39;s central hub  544  via a radial bearing  568  to rotate about axis A-A. As best seen in  FIG. 12 , the engine flexplate  566  if fabricated with a transmission-side cavity that nests therein the SOWC  556  and damper plate  560 . Damper assembly  526 , in turn, is interposed between the flexplate  566  and engine disconnect device  528 , with the flexplate  566  bolted directly to the engine hub  546 . 
     With continuing reference to  FIG. 12 , the SDS  562  mate the torsional damper plate  560  and the wedge-type SOWC  556  with the engine flexplate  566  such that the damper plate  560  and SOWC  556  (when engaged) rotate in unison with the flexplate  566  with limited rotational movement therebetween. In the vein of damper assemblies  26  and  126  of  FIGS. 2 and 5 , each SDS  562  of  FIG. 12  is seated within a respective spring receptacle  572  of the engine flexplate  566  such that the free lengths of the helical springs are elongated along the circumference of the flexplate  566 . When the flexplate  566  rotates under the driving power of the engine assembly  512 , spring retainers of each SDS  562  are pressed against respective circumferentially spaced walls of the spring receptacles  572 . This causes the springs of the SDS  562  to compress against integral spring tabs  574  that project axially from the damper plate  560 . Once the SDS  562  are sufficiently compressed, crankshaft torque is transmitted from the engine hub  546  and flexplate  566 , through the SDS  562  and damper plate  560 , to the wedge-type SOWC  528 . 
     In order to manage the transmission of rotational power and torque between the prime mover and final drive system, a wedge-type SOWC engine disconnect device  528  mechanically couples and selectively decouples engine  512  and TC assembly  518 . Like disconnect devices  28  and  128 , engine disconnect device  528  is operable to carry forward (positive) torque and reverse (negative) torque, overrun in both forward and reverse directions, and operatively disengage to freewheel in opposing forward and reverse directions. In the illustrated example, the wedge-type SOWC  558  includes an annular inner race  576  that is concentrically aligned within an annular outer race  578 . The inner race  576  is bolted, riveted, welded, integrally formed with or otherwise rigidly attached to the torsional damper plate  560  for mutual rotation therewith. Conversely, the outer race  578  is rigidly attached to the TC pump cover  542 , e.g., via rigid coupling to reaction ring  554 , for mutual rotation therewith. Projecting axially from the reaction ring  554  is an engine-side toroidal hub  555  within which is cupped the central hub  544  of pump cover  542 . Radial bearing  568  rotatably mounts the SOWC&#39;s inner race  576  onto the toroidal hub  555  and, thus, onto the pump cover&#39;s central hub  544 . A distal end face of the toroidal hub  555  nests within the transmission-side cavity of the flexplate  566 , limiting axial displacement of the flexplate  566  towards the TC assembly  518  and engine disconnect device  528 . While potentially less practical, it is envisioned that the outer race  578  may be mounted to the damper plate  560  with the inner race  576  mounted to the pump cover  542 . Furthermore, the outer (or inner) race  578  may be rigidly mounted to other TC input structure besides the pump cover  542 , such as the pump shell  540  or a TC input shaft. 
     Disposed between and selectively rotatably coupling the inner and outer races  576 ,  578  of the wedge-type SOWC  556  is a radially expandable and retractable wedge plate  580 . In accord with the illustrated example, wedge plate  580  may be fabricated as a single-piece, unitary structure with an annular shape and multiple circumferentially spaced ramps  582  (best seen in inset view of  FIG. 12 ). To enable measurable radial expansion/retraction during operation of the SOWC  528 , the wedge plate  580  may be fabricated as a discontinuous annulus or, alternatively, as continuous ring with integrally formed leaf-spring arms (not shown) that interconnect the ramps  582 . Each ramp  582  has a (first) variable radial width W d1  typified by a radial distance to the outer edge of the wedge plate  580  progressively decreasing (or increasing) in a clockwise (or counterclockwise) direction from left-to-right in the inset view of  FIG. 12 . The inner diameter (ID) surface of the SOWC outer race  578  is fabricated with numerous recessed grooves  579  that are circumferentially spaced from one another about the interior perimeter of the race  578 . Placed in opposing faced relation to the ID surface of the outer race  578  is an outer diameter (OD) surface of the inner race  576 , which is fabricated with several recessed pockets  577  that are circumferentially spaced from one another about the exterior perimeter of the race  576 . Each wedge plate ramp  582  is slidably mounted within one discrete groove  579  and one discrete pocket  577 ; with this configuration, the ramps  582  slide back-and-forth along an arcuate path that is rotationally centered at axis A-A. 
     With continuing reference to  FIG. 12 , the wedge plate  580  rotates back-and-forth about central axis A-A from an engaged (first) position to a disengaged (second) position. Moving the wedge plate  580  to the engaged position will frictionally wedge or “lodge” the ramps  582  between the ID and OD surfaces of the SOWC races  576 ,  578  to thereby transfer torque between the inner and outer races  576 ,  578 . Wedging the ramps  582  in this manner causes the races  576 ,  578  and wedge plate  580  to rotate un unison with one another. Contrariwise, shifting the wedge plate  580  to the disengaged position will unwedge or “dislodge” the ramps  582  from between the ID and OD surfaces of the SOWC races  576 ,  578 . Dislodging the ramps  582  frees the inner and outer races  576 ,  578  to rotate with respect to each other. One or more helical compression springs  584  bias the wedge plate  580  to the engaged position in order to preload the ramps  582  into their wedged states and place the SOWC in a lock-lock operating condition. 
     Each of the grooves  579  recessed into the ID surface of the outer race  578  has a semi-elliptical cam surface with a (second) variable radial width W d2 . Having a cammed surface allows the recessed grooves  579  to convert the sliding, arcuate motion of the ramps  582  into a linear compressive force that releasably fixes the wedge plate  580  to the races  576 ,  578 . Additionally, each pocket  577  recessed into the OD surface of the inner race  576  has a V-shaped or U-shaped cross-sectional profile (e.g., profile of pocket  577  best seen in outset view of  FIG. 12 ). An ID perimeter of the wedge plate  580 —opposite the OD perimeter with ramps  582 —has a rounded edge  581  that nests inside the recessed pockets  577  of the inner race  576 . Providing the wedge plate  580  with a rounded ID edge  581  that complements the profile of the pockets  577  provides a better frictional engagement and compressive lock between the wedge plate  580  and inner race  576 . It should be appreciated that the number, shape, distribution, and/or size of the ramps  582  may be modified from the illustrated example to accommodate other intended applications. Furthermore, wedge plate  580  may be fabricated as a one-piece structure, as shown, or may be segmented into discrete wedge plates arranged in a circular array between the two races  576 ,  578 . In addition, while shown with outwardly projecting ramped edges on the outer periphery of the wedge plate  580 , a wedge plate may have one or more inwardly projected ramped edges, as will be discussed in further detail below in connection with  FIG. 13 . 
     Analogous to the selector plate  50  of  FIGS. 2 and 3 , the selector plate  550  may be selectively actuable, e.g., via ECU  25  of  FIG. 1  through operation of hydraulic control circuit  200  of  FIG. 10 , to move back-and-forth along a rectilinear path to transition between deactivated and activated states. When activated, this selector plate  550  switches the wedge-type SOWC  556  from a torque-carrying (locked) state to a non-torque-carrying (freewheeling) state. Conversely, deactivating the selector plate  550  will switch the SOWC  556  from a non-torque-carrying state to a torque-carrying state. The deactivated selector plate  550  lays generally flush against the TC pump cover  542  and operatively disengages the wedge plate  580 . Selector plate  550  slides axially, e.g., from left-to-right in  FIG. 12  on a path parallel to axis A-A, from the deactivated to the activated state. Activating the selector plate  550  displaces it away from the pump cover  542  such that the plate  550  rotates the wedge plate  580 —against the preloading bias force of spring  584 —from the engaged state to the disengaged state. Rotating the wedge plate  580  in this manner operates to dislodge the ramps  582 , as described above. 
     To convert the translational motion of the selector plate  550  into the rotational motion of the wedge plate  580 , the selector plate  550  of  FIG. 12  may be fabricated with ramped shanks (e.g., integrally formed shanks  100  in the inset view of  FIG. 4 ). As noted above, these ramped shanks  100  may be circumferentially spaced in an equidistant manner about, and project axially from the selector plate&#39;s engine-side surface. The wedge plate  580  may be formed with a series of circumferentially spaced windows (e.g., windows  102  of  FIG. 4 ) that receive the ramped shanks  100 . Sliding the selector plate  550  from the deactivated position to the activated position will contemporaneously slide each ramped shank  100  against the inner perimeter of its corresponding window  102 . Axially angled contact surfaces of the shanks  100  apply a moment force to the wedge plate  580  via windows  102  to rotate the wedge plate  580  to the disengaged state. Shifting the select plate  550  back to the deactivated position will operatively disengage the ramped shanks  100  from the windows  102 , allowing the wedge plate  580  to rotate back to the engaged state and, thus, move the ramps  582  to their wedged positions. 
     Comparable to the back-to-back SOWC engine disconnect device  28 , engine disconnect device  528  of  FIG. 12  may employ hydraulically actuated, spring-loaded pistons  104  (e.g., piston  104  in  FIG. 3 ) to move the selector plate  550  to the activated state. A single piston or, if desired, a distributed arrangement of pistons may be mounted to the pump cover  542  of the TC assembly  518 , e.g., as described above with respect to piston  104  and TC assembly  18 . By increasing the hydraulic pressure inside the internal fluid chamber of the TC assembly  518 , the piston(s) will stroke, e.g., left-to-right in  FIG. 12 , and push the selector plate  550  to the activated state. Reducing this internal hydraulic pressure will allow each piston&#39;s return spring (e.g., helical springs  106 ) to bias the piston back to a deactuated position. At the same time, toroidal flex ring  552  presses against and biases the selector plate  550  to the deactivated state. Annular reaction ring  554 , which circumscribes the selector plate  550  and flex ring  552 , provides a reaction surface against which the flex ring  552  presses. 
     Presented in  FIG. 13  is another example of a wedge-type SOWC engine disconnect device  628  for drivingly engaging and disengaging an engine  612  to and from a torque converter assembly  618 . Unless stated otherwise, the general operation of the SOWC  656  of  FIG. 13  may be comparable to the general operation of the SOWC  556  of  FIG. 12 . For instance, in contrast to the representative architecture presented in  FIG. 12 , wherein the wedge plate  580  is displaced radially inward to lock to the inner race  576  to the outer race  578  of the SOWC  556 , the wedge-type SOWC  656  of  FIG. 13  includes a wedge plate  680  that displaces radially outward to lock to an inner race  676  to an outer race  678 . Another point of demarcation lies in the fact that the outer race  678  of  FIG. 13  is mechanically coupled directly to the TC pump cover  642 , e.g., via bolts  606 , whereas the inner race  676  is mechanically coupled directly to the engine hub  646 , e.g., via rivets  608 . Other differences include pockets  677 , which are recessed into the OD surface of the inner race  676 , being fabricated with cammed surfaces; grooves  679 , which are recessed into the ID surface of the outer race  678 , are fabricated with V-shaped or U-shaped cross-sectional profiles. In this regard, the ramps  682  face radially inward from the wedge plate  680 , whereas the rounded edge  681  projects radially outward. Lastly, the engine disconnect device  628  of  FIG. 13  employs an electronic solenoid  690 , rather than a hydraulic piston, to selectively shift the wedge plate  680  between engaged and disengaged positions and thereby change the operating status of the disconnect device  628  between locked and unlocked states. 
     Aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; those skilled in the art will recognize, however, that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; any and all modifications, changes, and variations apparent from the foregoing descriptions are within the scope of the disclosure as defined by the appended claims. Moreover, the present concepts expressly include any and all combinations and subcombinations of the preceding elements and features.