Patent Publication Number: US-10760622-B2

Title: Selectable one-way clutch having strut with separate armature

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/906,097 filed Jan. 19, 2016, which is a U.S. National Stage Application of International Patent Application No. PCT/CA2014/000586 filed Jul. 29, 2014, which claims the benefit of and priority to U.S. Provisional Application No. 61/859,514 filed Jul. 29, 2013 and U.S. Provisional Application 61/866,755 filed Aug. 16, 2013. The disclosure of each of the aforementioned applications is incorporated by reference as if fully set forth in its entirety herein. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure is generally related to overrunning coupling devices such as one-way clutches or brakes and, more specifically to selectable one-way coupling (SOWC) devices having an electromagnetic actuator assembly. 
     BACKGROUND OF THE INVENTION 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Automatic transmissions provide a plurality of forward and reverse speed or gear ratios by selectively actuating one or more clutches and/or brakes to establish a torque-transmitting drive connection between a transmission input and a transmission output for supplying motive power (i.e., drive torque) from a powertrain to a driveline in a motor vehicle. One type of brake or clutch widely used in automatic transmission is an overrunning coupling device, commonly referred to as a one-way clutch (OWC), which overruns when one of its races (in radial coupling configuration) or one of its drive plates (in axial coupling configurations) rotates in a first (i.e., freewheel) direction relative to the other race or drive plate, and engages or locks in a second (i.e., lockup) direction. Such conventional overrunning coupling devices provide no independent control over their modes of operation, that is to say whether they lockup or freewheel in both directions. Thus, basic one-way clutches provide a “locked” mode in one rotary direction and a “freewheel” mode in the opposite direction based on the direction that the drive torque is being applied to the input race or drive plate. 
     There are however, requirements in modern automatic transmissions where a “controllable” overrunning coupling device, commonly referred to as a selectable one-way clutch (SOWC), can be selectively controlled to provide additional functional modes of operation. Specifically, a selectable one-way clutch may further be capable of providing a freewheel mode in both rotary directions until a command signal (i.e., from the transmission controller) causes a power-operated actuator to shift the coupling device into its lockup mode. Thus, a selectable one-way clutch may be capable of providing a drive connection between an input member and an output member in one or both rotational directions and it may also be operable to freewheel in one or both directions. 
     In some instances, the selectable one-way clutches installed in automatic transmissions utilize a hydraulic actuator to selectively actuate the overrunning coupling and shift between the available operating modes. Examples of conventional selectable one-way clutches that are hydraulically-actuated are disclosed in U.S. Pat. Nos. 6,290,044, 8,079,453 and 8,491,439. In contrast, it is also known to use an electro-mechanical actuator with the selectable one-way clutch, one example of which is disclosed in U.S. Pat. No. 8,196,724. 
     As a further alternative, much development has recently been directed to electromagnetic actuators for use with selectable one-way clutches, examples of which are disclosed in U.S. Pat. Nos. 8,276,725 and 8,418,825 and U.S. Publication 2013/0319810. In most electromagnetic actuators, a rocker-type locking element, commonly referred to as a strut, is pivoted from a first position to a second position in response to energization of a coil assembly. In most conventional selectable one-way clutches equipped with an electromagnetic actuator, a direct-acting configuration is used such that the strut is part of the magnetic circuit and its pivotal movement is caused by an attraction force applied directly to the strut via energization of the coil assembly. Therefore, precise control of the air gap established between the core/pole piece of the coil assembly and the strut is required to provide robust and reliable lockup functionality. 
     While all of the different types of selectable one-way clutches mentioned above appear to meet all functional requirements, a need exists to continue development of new and improved power-operated actuators that advance the art and provide enhanced functionality. 
     SUMMARY OF THE INVENTION 
     This section provides a general summary of the disclosure and is not intended to be interpreted as a complete and comprehensive disclosure of all of its aspects, objectives, features and advantages. 
     It is an aspect of the present disclosure to provide an electromagnetic actuator module for use with a selectable one-way clutch having an indirect actuation configuration provided between the energizable coil assembly and the locking element. 
     It is another aspect to provide a selectable one-way clutch assembly comprised of a clutch mode and at least one electromagnetic actuator module having at least one electromagnetic actuator. The electromagnetic actuator includes an energizeable coil assembly, a locking strut, and an intermediate member mechanically connected to the locking strut and operable to move the locking strut between its released and locked positions relative to cam surfaces on a clutch member associated with the clutch module. 
     In accordance with these and other aspects of the present disclosure, a clutch assembly is provided having a clutch module and at least one electromagnetic actuator module. The clutch module includes a first clutch member and a second clutch member having a plurality of cam surfaces, at least one of the first and second clutch members being adapted to rotate relative to the other clutch member. The electromagnetic actuator module may include a frame adapted to be mounted to the first clutch member and at least one electromagnetic actuator mounted to the frame. The electromagnetic actuator includes an energizeable coil assembly secured to the frame, a connection member mounted to the frame for pivotal movement relative to the coil assembly between a non-actuated position and an actuated position, a locking member mechanically interconnected to the connection member for movement between a released position and a deployed position in response to pivotal movement of the connection member between its non-actuated position and its actuated position, and a biasing member for normally biasing the locking member into its released position. Energization of the coil assembly generates a magnetic circuit that causes the connection member to move to its actuated position which concomitantly causes the locking member to move to its deployed position in opposition to the biasing exerted by the biasing member. The locking member is released from engagement with the cam surfaces when located in its released position and is lockingly engaged with one of the cam surfaces when located in its deployed position. 
     In accordance with one embodiment, the connection member is a magnetic armature having a first end segment pivotably coupled to the frame and a second end segment mechanically interconnected to the locking member. In one preferred arrangement, the armature and locking member are oriented in an offset configuration. In another preferred arrangement, the armature is oriented to be located between the coil assembly and the locking member in an under-strut configuration. 
     In accordance with another embodiment, the coil assembly is a solenoid having a linearly-moveable plunger operably coupled to the connection member to control movement of the connection member in response to energization of the solenoid. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description, drawings and specific example provided hereinafter. It should be understood that the detailed description, drawings and specific examples, while indicating preferred embodiments of the present disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure. The inventive concepts associated with the present disclosure will be more readily understood by reference to the following description in combination with the accompanying drawings wherein: 
         FIG. 1  is an isometric view of a selectable one-way clutch (SOWC) shown to include a clutch module and an electromagnetic actuator module and which is constructed in accordance with the present disclosure; 
         FIG. 2  is an enlarged partial view of  FIG. 1  showing components of the electromagnetic actuator module in greater detail; 
         FIG. 3  is a sectional view of the electromagnetic actuator module taken generally along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is another sectional view of the electromagnetic actuator module; 
         FIG. 5  is an isometric view of a selectable one-way clutch which is generally similar to the selectable one-way clutch of  FIG. 1 , but now showing a plurality of electromagnetic actuator modules associated with the clutch module; 
         FIG. 6  is a detailed view of an alternative configuration for an electromagnetic actuator module adapted for use in association with the clutch module; 
         FIG. 7  is a detailed view of yet another alternative configuration for an electromagnetic actuator module adapted for use in association with the clutch module; 
         FIG. 8  is a sectional view of the electromagnetic actuator module shown in  FIG. 7 ; 
         FIG. 9  is a detailed side view of a bi-directional electromagnetic actuator module constructed in accordance with the present disclosure and arranged for use in association with a bi-directional version of the clutch module; 
         FIG. 10  is a detailed view of a selectable one-way clutch equipped with an alternative embodiment of a bi-directional electromagnetic actuator module for use in association with the bi-directional clutch module of  FIG. 9 ; 
         FIG. 11  is a sectional view of the bi-directional electromagnetic actuator module shown in  FIG. 10 ; 
         FIG. 12  is an isometric view of another embodiment of an electromagnetic actuator module constructed in accordance with the present disclosure; 
         FIG. 13  is a sectional view taken through the electromagnetic actuator module of  FIG. 12 ; 
         FIG. 14  is another sectional view taken through the electromagnetic actuator module of  FIG. 12 ; 
         FIG. 15  is a sectional view illustrating a magnetic leakage path between the strut and the housing in direct-acting electromagnetic actuator modules; 
         FIGS. 16A through 16C  are perspective view of a tapered pole piece/strut configuration for the direct-acting electromagnetic actuator modules constructed in accordance with the present disclosure; 
         FIG. 17  is a side view of an electromagnetic actuator module adapted for use with the clutch module and having a moveable armature arranged to control pivotal movement of the strut, wherein the armature and strut are oriented in an “offset” configuration; 
         FIG. 18  is a perspective view of an alternative version of the electromagnetic actuator module shown in  FIG. 17 , with the armature oriented in an “under-strut” configuration; 
         FIG. 19  is a sectional view taken through the electromagnetic actuator module of  FIG. 18 ; 
         FIGS. 20 and 21  are perspective views of alternative constructions for the under-strut electromagnetic actuator module of  FIG. 18  incorporating tapered pole arrangements; 
         FIG. 22  is an isometric view of another alternative constructions for the under-strut electromagnetic actuator module of the present disclosure; 
         FIG. 23  is a side view of  FIG. 22 ; 
         FIG. 24  is a sectional view of the electromagnetic actuator module of  FIG. 22  illustrating the strut positioned in a first or non-deployed position; 
         FIG. 25  is a sectional view of the electromagnetic actuator module of  FIG. 22  illustrating the strut positioned in a second or deployed position; 
         FIG. 26  is a sectional view of the electromagnetic actuator module shown in  FIG. 18  equipped with a single coil type of coil assembly; 
         FIG. 27  is an isometric perspective view showing the electromagnetic actuator module of  FIG. 18  with the strut located in its deployed position; 
         FIG. 28  is a sectional view similar to  FIG. 26  but illustrating an electromagnetic actuator module equipped with a double coil type of coil assembly; 
         FIG. 29  is a detailed view of the double coil assembly shown in  FIG. 28 ; 
         FIG. 30  is an isometric view similar to  FIG. 27  but now showing the double coil assembly of  FIGS. 28 and 29 ; 
         FIG. 31  illustrates yet another embodiment of an under-strut type of electromagnetic actuator module constructed in accordance with the present disclosure; and 
         FIG. 32  is a sectional view of a further embodiment of an under-strut electromagnetic actuator module of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. Each of the example embodiments is directed to an electromagnetically-actuated overrunning coupling device, hereinafter referred to as a selectable one-way clutch (SOWC). In general, each example embodiment employs one or more electromagnetic actuator modules in a SOWC which advances the technology over conventional SOWC products. However, the example embodiments only are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The present disclosure is generally related to electromechanical rocker clutches that function to transmit torque mechanically but which are actuated via electrical actuation/controls. When a voltage and/or current is applied to an electromagnetic coil assembly or a plurality of coil assemblies, the coil assemblies becomes an electromagnet and produces a magnetic field. The magnetic flux flows around a magnetic circuit established between the components and is transferred across a small air gap between a moveable rocker-type locking member, commonly referred to as a strut, and a core/pole unit associated with the coil assembly. Magnetization of the core/pole unit functions to magnetically attract the strut for moving the strut from a first or “released” position toward a second or “locked” position. The strut is normally biased toward its released position by a biasing spring. In accordance with alternative arrangements, the magnetic flux flows around the magnetic circuit and is transferred across a small air gap established between a moveable armature and a core/pole unit associated with the coil assembly. Magnetization of the core/pole unit functions to magnetically attract the armature for moving the armature from a first or “non-actuated” position toward a second or “actuated” position. The resulting movement of the armature from its first position to its second position causes the strut to move from its “released” position toward its “locked” position based on a mechanical connection established between the strut and the armature. The coil assembly, the armature, and the strut define an electromagnetic actuator that is mounted to a first member of a clutch module. 
     Movement of the strut to its locked position causes a locking segment of the strut to engage one of a plurality of locking teeth associated with a second member of the clutch module, thereby coupling the first member to the second member for rotation together or against rotation in a certain rotational direction. Disengagement occurs as the voltage and/or current is removed from the coil assembly such that the strut or the armature is demagnetized and freed from attraction toward the core of the coil assembly. As such, the biasing member is permitted to forcibly urge the strut to pivot from its locked position back to its released position which, in turn, causes the armature to move from its actuated position to its non-actuated position. 
     In accordance with the present invention there is provided a clutch assembly, generally shown at  10 , of the type, for example, for use in an automatic transmission (not shown) which is controlled using an on-off relay to actuate a clutch mechanism. Clutch assembly  10  is disclosed to be a controllable overrunning coupling device, commonly referred to as a selectable one-way clutch (SOWC). For the purpose of this application, the term “clutch assembly” should be interpreted to include couplings, clutches and brakes wherein one component is driveably connected to a torque delivery component of the transmission while the other component is driveably connected to another torque delivery component or is non-rotatably fixed to a transmission housing or stationary component. As such, the terms “coupling”, “clutch” and brake may be used interchangeably. 
     Referring to the drawings, and initially to  FIGS. 1-4 , there is provided a clutch assembly  10  having a clutch module  11  and at least one electromagnetic actuation module  14 . The clutch module  11  includes a first clutch member  12  supporting the at least one elctromagnetic actuation module  14 , and a second clutch member  16  having a plurality of cam surfaces  17  formed thereon which are configured for selective engagement with a moveable locking element associated with electromagnetic actuation module  14 . The clutch members  12  and  16  are aligned co-axially adjacent to each other and at least one of the clutch members is adapted to rotate relative to the other clutch member. The clutch members  12  and  16  include engagement hubs or splines  12   a  and  16   a  respectively to facilitate connection of each to another rotary or non-rotary component of the transmission. 
     The electromagnetic actuation module  14  is generally shown to include a frame  18  with a single electromagnetic actuator  15 . The electromagnetic actuator  15  includes a locking element or strut  20  that is pivotally movable with respect to frame  18  about a pivot  22 . Frame  18  is adapted to be fixedly secured to first clutch member  12  in the particular configuration shown. The strut  20  includes an engagement end segment  26  and a base end segment  24  and further includes a first side segment  28  and a second side segment  30 . A pin or post  32  extends from the frame  18 . The electromagnetic actuator  15  also includes a coil assembly  35  mounted on post  32 . The coil assembly  35  includes an insulated bobbin  34  with an energizable coil  36  that is wound to surround the bobbin  34 , and a U-shaped pole member  37  that is secured magnetically and mechanically to the post  32  by way of a screw or other fastener  39 . The U-shaped pole member  37  includes a pair of laterally-spaced actuation leg sections  38  and  40  interconnected by a base segment  41 . A biasing spring  42  (such as the accordion spring shown) is provided in a bore  44  formed in post  32  of frame  18 . At rest, the biasing spring  42  acts on the strut  20  and biases the engagement end segment  26  out of engagement with the cam surfaces  17  to provide a normally disengaged or freewheeling condition, whereby second clutch member  16  is permitted to rotate relative to first clutch member  12 . The peripheral ends  46  and  48  of pole leg segments  38  and  40  form a magnetic air gap with respect to the base end segment  24  of the strut  20 . 
     When the coil  36  is energized, the peripheral ends  46  and  48  of the leg segments  38  and  40  are polarized in a first polarity and the frame  18  and the strut  20  are polarized with an opposite polarity, thereby attracting base end segment  24  of the strut  20  toward the peripheral ends  46  and  48 . This attraction causes the engagement end segment  26  of the strut  20  to pivot into engagement with one of the cam surfaces  17  on the second clutch member  16 . 
     Typically, the electromagnetic actuation module  14  may be contained in or mounted to metallic frame  18 . Thus, in the present invention, the frame  18  can be used as an integral component of the magnetic circuit for controlling actuation of the clutch assembly  10 . When the coil  36  is powered, the frame  18  is magnetized and will take a particular polarity (i.e., either north or south as may be desired) that is opposite from a polarity of the magnetic poles of the actuator which, in this instance, is the U-shaped pole member  37 . Since the frame  18  is in contact with struts, the struts will be magnetized with the same polarity as the frame  18 . In this application, the attraction force between the strut ends and the magnetic poles of the U-shaped pole member  37  (i.e., across the air gap between them) is greatly increased as compared with the case where the struts carry a neutral charge from a magnetic perspective. 
     While the strut  20  is shown to be pivotably supported on a pin  22  from frame  18 , it is to be appreciated by those skilled in the art that the strut can also be configured for pivotable movement within a recess formed in frame  18  or, in the alternative, formed within a suitable housing portion of the first member  12 .  FIG. 15  is generally similar to  FIG. 1  except that a plurality of electromagnetic actuation modules  14  are shown in association with clutch module  11 . Specifically, a plurality of four (4) equally-spaced actuation modules  14  are secured to first clutch member  12  of clutch module  11 . Obviously, any number of actuation modules  14  can be used, as well as circumferentially spaced in any desired orientation, to provide a selectable one-way clutch assembly. 
     As can be seen from  FIG. 6 , an alternative embodiment of an electromagnetic actuation module  14 A is generally similar to electromagnetic actuation module  14  of  FIG. 2 , except that a pair of struts and coil electromagnetic actuators  15  are mounted to a common frame  18 ′. Each electromagnetic actuator  15  is identified by common reference numerals, but has “a” and “b” suffixes. Accordingly, all of the coils  36   a  and  36   b  (e.g., two in the embodiment shown) will work together to magnetize frame  18 ; thereby increasing the magnetic field intensity and generating a greater magnetic attraction force in the struts  20   a ,  20   b  for pivoting them from the released position toward the deployed or locked position. 
     Referring now to  FIGS. 7 and 8 , there is provided another alternate embodiment of an electromagnetic actuation module  14 B for use with clutch assembly  10 . Actuation module  14 B includes a pair of pivotal struts  112  and  114  which pivot on pins  116  and  118  respectively, and are attached to a frame  120  that is rigidly secured to first clutch member  12 . A pole component  122  is provided which includes a first or front U-shaped member  124  and a second or rear U-shaped member  126  which are magnetically and electrically coupled to one another through a connection base member  128 . Front U-shaped member  124  includes a pair of leg segments defining outer peripheral end portions  130  and  132  which engage the first sides of the struts  112  and  114 . Rear U-shaped member  126  includes a pair of leg segments defining inner peripheral end portions (not shown) which are generally aligned respectively with outer peripheral end portions  130  and  132  and which engage the rear sides of struts  112  and  114 . A single coil assembly having a central bobbin  134  and a coil winding  136  energizes the pole component  122  for providing the coordinated actuation of the multiple struts. It will be readily appreciated that while two struts are shown in association with electromagnetic actuator module  14 B, this invention could be configured to actuate more than just two struts if desired. As best shown in  FIG. 8 , biasing springs  138  and  140  are provided for normally biasing the struts  112  and  114  into a freewheeling position.  FIGS. 7 and 8  illustrate energization of coil  136  for causing the engagement end segments of the struts  112 ,  114  to be moved into engagement with ratchet teeth  17  on second clutch member  16 . 
       FIG. 9  shows the use of a pair of mirror-image electromagnetic actuation modules  14  and  14 ′ of the type originally shown in  FIGS. 1-4  and as discussed above with the mirror image parts being labeled with primed numbers. The second clutch member  16 ′ in this embodiment includes bi-directional cam members  17  and  17 ′. In operation, either actuation module, or sets of modules  14  or  14 ′, can be energized depending on the direction which is desired for engaging or rotating the second clutch member  16 ′ with respect to first clutch member  12 . Accordingly,  FIG. 9  illustrates a bi-directional selectable clutch assembly  10 ′. 
     Referring now to  FIGS. 10 and 11  there is shown another embodiment of a bi-directional selectable clutch assembly  10 ″ equipped with an electromagnetic actuation module  210 . In this particular embodiment, a symmetrical strut member  212  is pivotally attached by a pin  214  to a frame  216 . A pair of U-shaped pole members  218  and  220  with separate coil and bobbin assemblies  222  and  224  are used to selectively actuate the strut  212  from a freewheel position. Biasing springs  228  and  230  are provided for cooperatively biasing the strut  212  to its free-wheeling position.  FIG. 10  shows first coil/bobbin assembly  222  energized to cause strut  212  to move from its free-wheeling position into a first locked position such that end segment  212   a  engages cam surface  17  on clutch member  226  and prevents relative rotation in a first direction. In contrast,  FIG. 11  shows second coil/bobbin assembly  224  energized to cause strut  212  to move from the free-wheeling position to a second locked position such that its end segment  212   b  engages cam surface  17 ′ on clutch member  226  and prevents relative rotation in a second direction. 
     Referring now to  FIGS. 12 through 15 , another alternative construction for an electromagnetic actuator module  14 C is disclosed that is generally similar to electromagnetic actuator module  14  of  FIG. 2  with the exception that a plurality of three electromagnetic actuators  300  are mounted to a common frame  302  that is adapted to be rigidly secured to first clutch member  12  of the clutch module. Each electromagnetic actuator  300  includes a strut  304 , a coil assembly  306 , a U-shaped pole member  308 , and a biasing member  310 . Struts  304  include a pivot end segment  312  and an engagement end segment  314 . Pivot end segment  312  of each strut  304  is seated in an axially-extending pivot channel  316  formed in a recessed portion  318  of frame  302 . Each biasing member  310  is seated within a radial bore  320  formed in recessed portion  318  and is arranged to engage a surface portion  322  of pivot end segment  312  on a corresponding strut  304 . Biasing members  310  are arranged to normally bias struts  304  to the released position shown. “Contoured” air gaps are established between surface portion  322  on pivot end segment  312  of each strut  304  and terminal ends  324 ,  326  of legs  325 ,  327  on each U-shaped pole member  308 . This air gap is best illustrated in  FIGS. 14 and 15 . 
     U-shaped pole member  308  is secured magnetically and mechanically to a post portion  328  of coil assemblies  306  via a fastener  330 . When coil assemblies  306  are energized, a magnetic circuit is established which causes pivot end segment  312  of struts  304  to pivot within pivot channels  316 , in opposition to the biasing force applied thereon by biasing members  310 , and cause engagement end segments  314  to move to its locked/deployed position for engagement with cam surfaces  17  on second clutch member  16 . Since struts  304  are part of the magnetic circuit, they tend to be attracted to poles  325 ,  327  as well as frame  302 . 
     To improve the magnetic attraction, the air gap between poles  325 ,  327  and struts  304  can be reduced as the force of attraction increases with reductions in the air gap. To achieve this improvement, a “tapered” profile is provided to one of surface  322  of struts  304  and/or terminal ends  324 ,  326  of poles  325 ,  327 .  FIGS. 16A through 16C  illustrate a specific example of such a tapered profile. In particular, each terminal end  324 ,  326  has an acute attraction surface  340  cooperating with a facing arcuate surface  342  formed on opposite edges of each pivot end  312  of struts  304 . The profiles of surfaces  340  and  342  are not complimentary and are configured to reduce the air gap therebetween as struts  304  pivot from their released position toward their deployed position. The complex profile of each surface  340  and  342  is illustrated to be indicative of any non-complimentary surfaces intentionally configured to vary the magnetic attraction force. In contrast,  FIG. 15  illustrates a sectional view of non-tapered or complimentary surfaces associated with pivot end of struts  304  and terminal end surfaces  324 ,  326  of poles  325 ,  327 . As illustrated, in such direct-acting actuating systems, a leakage path (Arrows  341 ) in the magnetic field occurs between struts and frame. Even though this leakage field is weak, the attraction forced produced is counter to the attraction force produced in the primary working gaps. 
     In an effort to address and overcome known deficiencies in direct-acting strut-type electromagnetic actuators, the present disclosure is also directed to a number of “indirect” strut-type electromagnetic actuators that are configured to integrate an intermediate element between the coil assembly and the strut. In particular, an improved selectable one-way clutch is provided which eliminates, or at least greatly reduces, the magnetic field in the strut by introducing a magnetic armature which the magnetic poles of the coil assembly act upon. As will be detailed, the armature pivots about a point in the frame/housing and has features which mechanically engage the end segment of the strut and which functions to control pivotal movement of the strut. 
     Referring now to  FIG. 17 , an electromagnetic actuator module  14 D for use with the clutch module  11  in a selectable one-way clutch is shown to include an electromagnetic actuator  400  having a frame  402 , a coil assembly  404 , an armature  406 , and a strut  408 . Frame  402  is adapted to be rigidly secured to first clutch member  12  and includes a recessed pocket or chamber defining an armature chamber  410  and a strut chamber  412 . Armature  406  is elongated magnetic component having a first end segment  414 , a second end segment  416 , and an underside surface  418 . First end segment  416  is retained in a pivot channel  420  formed in armature chamber  410  to facilitate pivotal movement of armature  406  relative to coil assembly  404  between a first or “non-actuated” position (shown) and a second or “actuated” position. 
     Strut  408  is an elongated non-magnetized component having a base end segment  422  and an engagement end segment  424 . As seen, second end segment  416  of armature  406  is retained in a coupling channel  426  formed in base end segment  422  of strut  408 . Likewise, base end segment  422  of strut  408  is disposed within a pivot channel  428  formed in strut chamber  412 . A biasing spring (not shown) is retained in a bore formed in pivot channel  428  and acts against base end segment  422  to normally bias strut  408  toward its released position shown. The mechanical interaction between strut  408  and armature  406  is designed to locate armature  406  in its non-actuated position when strut  408  is in its released position. Note that strut  408  engages a locator post  430  when located in its released position. 
     Coil assembly  404  is generally similar to those previously described and includes a U-shaped pole component  434  and, coil windings  436  on a bobbin  438  which are rigidly connected via a center core (not shown) to frame  402  via a suitable fastener (not shown). Upon energization of coil windings  436 , the magnetic circuit generated causes armature  406  to be attracted to end segments  440  of the laterally-spaced arm segments  442  (one shown) associated with U-shaped pole component  434 , thereby causing armature  406  to pivot from its non-actuated position toward its actuated position. Such pivotal movement of armature  406  causes concomitant pivotal movement of strut  408  from its released position to its deployed/locked position due to the mechanical connection established therebetween. 
     The electromagnetic actuator module  14 D can be used in association with a single electromagnetic actuator  400  (similar to  FIG. 1 ); a plurality of actuator electromagnetic modules  14 D arranged circumferentially around first clutch member  12  (similar to  FIG. 5 ); arranged in a plurality of actuators  400  as part of a subassembly (similar to  FIG. 6 ); arranged in a mirror-image configuration (similar to  FIG. 9 ); or in any other suitable arrangement in association with a selectable one-way clutch. The configuration shown in  FIG. 17  is referred to as an “offset” arrangement where armature  406  and strut  408  are aligned in a lengthwise orientation. 
     Referring now to  FIGS. 18 and 19 , an “under-strut” configuration for an indirect-acting electromagnetic actuator  500  installed in an electromagnetic actuator module  14 E is shown and which is also adapted for use with the clutch module  11  in a selectable one-way clutch. Electromagnetic actuator module  14 E is shown to generally include a frame  502  and at least one electromagnetic actuator  500 . Each electromagnetic actuator  500  includes a coil assembly  504 , an armature  506  and a strut  508 . Frame  502  is adapted to be rigidly secured to first clutch member  12  and includes a recessed chamber  510 . Armature  506  is an elongated magnetic component having a first end segment  514 , a second end segment  516 , and an underside surface  518 . First end segment  514  is retained in a pivot channel  520  formed in chamber  510  to facilitate pivotal movement of armature  506  relative to coil assembly  504  between its non-actuated position ( FIG. 18 ) and its actuated position ( FIG. 19 ). 
     Strut  508  is an elongated non-magnetized component having a base end segment  522  and an engagement end segment  524 . As seen, second end segment  516  of armature  506  is retained in a U-shaped channel  526  formed in base end segment  522  of strut  508 . Base end segment  522  is disposed within a pivot channel  528  formed in chamber  510 . A biasing spring (not shown) is retained in a bore formed in frame  502  which is in communication with pivot channel  528 . The biasing spring acts against base end segment  522  of strut  508  to normally bias strut  508  toward its released position ( FIG. 18 ). The mechanical interaction between armature  506  and strut  508  is configured to locate armature  506  in its non-actuated position when strut  508  is biased into its released position. 
     Coil assembly  504  is again generally similar to those previously described and includes a U-shaped pole member  534  and a coil winding  536  on a bobbin  538 , both of which are rigidly connected via a core post  539  to frame  502  via a suitable fastener (not shown). Upon energization of coil windings  536 , the magnetic circuit generated causes armature  506  to be attracted to end segments  540 A,  540 B of a pair of laterally-spaced arm segments  542 A,  542 B on pole component  534 .  FIG. 19  illustrates the magnetic flux path and the working gaps upon energization of coil assembly  504 . This attraction causes armature  506  to pivot from its non-actuated position toward its actuated position which, in turn, concomitantly causes pivotal movement of strut  508  from its released position toward its deployed/locked position. 
     The under-strut arrangement disclosed in  FIGS. 18 and 19  provides a compact actuator assembly  500  that can be readily adapted for use in any of the clutch assembly configurations previously disclosed. In addition, the location of the biasing spring can be varied to directly engage either strut  508  or a portion of armature  506  within chamber  510  so long as it functions to normally bias the interconnect components to the non-actuated/released positions. 
     Referring now to  FIGS. 20 and 21 , modified versions of the under-strut electromagnetic actuator  500 ′ for use with electromagnetic actuator module  14 E of  FIGS. 18 and 19  are disclosed to incorporate the “tapered” pole features previously disclosed. Specifically, electromagnetic actuator  500 ′ of  FIG. 20  is generally similar to actuator assembly  500  of  FIG. 18  with the exception that armature  506 ′ and U-shaped pole member  534 ′ have been modified to provide a tapered working gap. As seen, armature  506 ′ includes a pair of laterally-spaced leg sections  550  (one shown) that are aligned with leg sections  542 A′,  542 B′ of pole member  534 ′. In particular, armature legs  556  each define an “angled” edge surface  552  aligned with an angled edge surface  540 A′,  540 B′. Armature  506 ′ is still pivotable between its non-actuated and actuated positions. The configuration of the tapered/angled air gaps is designed to locate the attractions force for applying torque around the armature&#39;s pivot point.  FIG. 21  is generally similar to  FIG. 20  with the exception that actuate edge surfaces  552 ″ on armature  506 ″ are aligned with arcuate edge surfaces  540 A″,  540 B″ on pole piece  534 ″. The terms angled and arcuate are intended to encompass all non-planar configurations that provide a tapered air gap profile. 
     As will be appreciated, the tapered pole arrangement shown in  FIGS. 20 and 21  in association with an under-strut configuration can likewise be implemented with an offset electromagnetic actuator similar to that shown in  FIG. 17 . 
     Referring now to  FIGS. 22-25 , another embodiment of an under-strut electromagnetic actuator  600  is shown and which is also applicable for use with all the previously disclosed clutch modules in a selectable one-way clutch. Electromagnetic actuator assembly  600  is generally similar to electromagnetic actuator  500  shown in  FIGS. 18, 19, 26 and 27 , with the exception that the coil assembly  504  has been replaced with an electromagnetic solenoid assembly  604 . As such, component  606  is no longer a magnetized armature, but rather functions as a mechanical linkage member  606 . A linearly-moveable armature  608 , associated with solenoid assembly  604 , is coupled to linkage member  606  via a post  610 . A stem portion  612  of post  610  passes through an aperture  614  in housing  502  and an aperture  615  in linkage member  606  and a head portion  616  is fixedly attached to stem portion  612 .  FIGS. 22, 23 and 24  illustrates the location of the components when a solenoid coil  620  is not energized such that strut  508  is biased (by the biasing member) to its released position which, in turn, locates linkage member  606  in its non-actuated position. In contrast,  FIG. 25  illustrates that, when solenoid coil  620  is energized, armature  608  is retracted and head portion  616  acts on linkage member  606  for forcibly moving it to its actuated position which, in turn, results in pivotal movement of strut  508  to its deployed/locked position. Actuator assembly  600  is adapted to use in selectable one-way clutches if additional protection from contamination is required due to solenoid assembly  604  being enclosed and directly mounted to frame  502 . 
     As previously noted,  FIGS. 26 and 27  illustrate under-strut electromagnetic actuator assembly  500  in association with housing/frame  502  of module  14 E. In an effort to improve thermal performance (run cooler) and electrical draw (less current), more copper must be added to coil winding  536 . As an alternative, instead of mounting a single coil assembly on central leg/core member  539 ,  FIGS. 28-30  illustrate an under-strut electromagnetic actuator assembly  700  equipped with as modified coil assembly  702  that is adapted for use in substitution for coil assembly  504  (or  404  in  FIG. 17 ). In this regard, coil assembly  702  includes a bobbin  704  having a base portion  706  and a pair of spools  708 ,  710  that are configured to surround a portion of leg sections  542 A,  542 B of pole member  534 . Coil windings  712 ,  714  are wound on respective spools  708 ,  710  (not shown in  FIG. 28 ). As such, significantly more coil winding material can be utilized with coil assembly  702 . Coils  712 ,  714  are wound in a direction such that the flux is directed in the same manner as a single coil design. The two coils  712 ,  714  can be connected in series or parallel. This arrangement permits use of reduced current draws and operating temperatures.  FIG. 30  indicates that additional windings can be wound on leg sections  542 A,  542 B. 
       FIG. 31  illustrates another version of an electromagnetic actuator assembly  800  adapted for use with an previous actuator module and clutch module  11  to define a selectable one-way clutch in accordance with the present disclosure. In particular, a modified coil assembly  802  is shown associated with many components similar to those of electromagnetic actuator assemblies  500 ,  600  and  700 , such that like reference numerals are again used to identify the common components. Generally speaking, coil assembly  802  includes a pot-shaped base pole piece  804  having an elongated center pole section  806  about which the bobbin/windings  808  is installed within the internal toroidal chamber. An end  810  of base pole piece  804  is fixed within a retention aperture  812 . Upon energization of the col assembly, armature  506  is magnetically attracted to center pole section  806 , in opposition to the biasing force of the biasing spring (not shown), for causing pivotal movement of strut  508  to its deployed position. Thus, a single center pole is employed with base  804  being used as part of flux return path, thereby defining a pot-core magnetic circuit. 
       FIG. 32  illustrates yet another version of an electromagnetic actuator assembly  900  adapted for use in association with an previously disclosed actuator module and/or clutch module to define a selectable one-way clutch constructed in accordance with the present disclosure. Specifically, coil assembly  902  includes a pot-shaped base member  904  having a center pole segment  906 . Base pole member  904  is adapted to be mounted to frame  502  for connection to first clutch member  12  of the clutch module  11 . A frusto-conical male end portion  908  of center pole  906  is positioned in close proximity to a frusto-conical female end portion  910  of a linearly-moveable armature plunger  912 . Armature plunger  912  is slideably disposed within a bore  914  extending through frame  502  and has a post segment  916  fixedly secured to a pivotal intermediate member  920 . An isolator tube may be used to magnetically isolate armature plunger  912  from housing  502 . Intermediate member  920  is identical in structure to armature  506  of assembly  500 , but now is configured to only provide a mechanical connection between sliding armature or plunger  912  and strut  508 . An conical air gap  922  is provided between plunger end portion  910  and male end portion  908  of center pole  906 . Upon energization, armature plunger  912  is retracted inwardly which, in turn, causes intermediate member  920  to pivot from the non-actuated position shown to its actuated position. As before, such pivotal movement of member  920  results in pivotal movement of strut  508  from its released position into its deployed position. Since the air gap  422  is centrally located, its improves the attraction force and reduces flux leakage in the magnetic circuit. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.