Abstract:
A clutched device that includes a pulley, a shaft member, a first one-way clutch having a first wrap spring, and an actuator having an electromagnetic coil and an armature. The first one-way clutch rotationally couples the pulley and the shaft member when the actuator is actuated and rotary power is transmitted from a first one of the pulley and the shaft member to the other one of the pulley and the shaft member in a first rotational direction. A frictional force is applied to the armature when the actuator is activated. The frictional force is configured to resist rotation of the armature to cause the first wrap spring to radially expand into driving engagement with a clutch surface that is coupled to the pulley for common rotation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit and priority of U.S. Provisional Patent Application No. 61/471,222, filed Apr. 4, 2011, the entire disclosure of which is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to a clutch mechanism and to a decoupler device with a clutch mechanism. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    Serpentine accessory drive systems for automotive vehicles are commonly used to transfer power, via associated pulleys, from an internal combustion engine crankshaft to accessory components such as alternators, water pumps, power steering pumps, and air conditioning compressors. Under operating conditions where the crankshaft slows suddenly, high-inertia components of the accessory drive will tend to load the serpentine belt such that the belt may squeal or slip, and/or vibrate, and/or cause the tensioner and/or accessory components to vibrate. 
         [0005]    It is known to counter this effect with an over-running decoupler, which may be positioned on one of the high-inertia components or on the engine crankshaft. Examples of such devices are disclosed in U.S. Pat. Nos. 7,618,337; 7,591,357 and 7,624,852. While such devices are well suited for their intended purpose, we have noted that it would be desirable to lock, bypass or otherwise transmit rotary power through the over-running decoupler in some situations. One such situation involves a BAS (i.e., “belt-alternator-starter”) system in which a belt-driven alternator may be operated as a starter motor that will provide rotary power to the serpentine belt for rotating the crankshaft during starting of the internal combustion engine. 
         [0006]    An overrunning-enabled automotive starter generator is disclosed in International Publication No. WO 03/104673 (International Application No. PCT/CA03/00852) published Dec. 18, 2003. While such device is suited for its intended purpose, there remains a need in the art for an improved clutched device. 
       SUMMARY 
       [0007]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0008]    In one form, the present teachings provide a clutched device that includes a pulley, a shaft member, a first one-way clutch having a first wrap spring, and an actuator having an electromagnetic coil and an armature. The first one-way clutch rotationally couples the pulley and the shaft member when the actuator is actuated and rotary power is transmitted from a first one of the pulley and the shaft member to the other one of the pulley and the shaft member in a first rotational direction. A frictional force is applied to the armature when the actuator is activated. The frictional force is configured to resist rotation of the armature to cause the first wrap spring to radially expand into driving engagement with a clutch surface that is coupled to the pulley for common rotation. 
         [0009]    In another form, the present teachings provide a clutched device that includes a housing, a shaft member, a pulley, an over-running decoupler, a one-way clutch, and an actuator. The over-running decoupler rotationally couples the shaft member and the pulley when rotary power is transmitted from one of the shaft member and the pulley to the other one of the shaft member and the pulley in the first rotational direction. The over-running decoupler does not transmit rotary power between the shaft member and the pulley when the other one of the shaft member and the pulley overruns the one of the shaft member and the pulley in the first rotational direction. The one-way clutch has a wrap spring. The actuator is configured to control operation of the one-way clutch and includes an armature. The one-way clutch rotationally couples the pulley and the shaft member when the actuator is actuated and rotary power is transmitted from the first one of the shaft member and the pulley to the other one of the shaft member and the pulley in the first rotational direction. A frictional force is applied to the armature when the actuator is activated. The frictional force is configured to resist but not inhibit rotation of the armature relative to the housing to cause the first wrap spring to radially expand into driving engagement with a clutch surface that is coupled to the pulley for common rotation. 
         [0010]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0011]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0012]      FIG. 1  is a schematic illustration of a first exemplary clutch controlled decoupler constructed in accordance with the teachings of the present disclosure and shown in operative association with an internal combustion engine; 
           [0013]      FIG. 2  is an exploded perspective view of the clutch controlled decoupler of  FIG. 1 ; 
           [0014]      FIG. 3  is a perspective longitudinal section view of the clutch controlled decoupler of  FIG. 1 ; 
           [0015]      FIG. 4  is an enlarged portion of  FIG. 3 ; 
           [0016]      FIG. 5  is a schematic illustration of a second exemplary clutch controlled decoupler constructed in accordance with the teachings of the present disclosure and shown in operative association with an internal combustion engine; 
           [0017]      FIG. 6  is an exploded perspective view of the clutch controlled decoupler of  FIG. 5 ; 
           [0018]      FIG. 7  is a perspective longitudinal section view of the clutch controlled decoupler of  FIG. 5 ; 
           [0019]      FIG. 8  is a perspective longitudinal section view of a driven accessory with a clutch unit constructed in accordance with the teachings of the present disclosure; 
           [0020]      FIG. 9  is an exploded perspective view of a third exemplary clutch controlled decoupler constructed in accordance with the teachings of the present disclosure; 
           [0021]      FIG. 10  is an exploded perspective section view of the clutch controlled decoupler of  FIG. 9 ; and 
           [0022]      FIG. 11  is a longitudinal section view of the clutch controlled decoupler of  FIG. 9 . 
       
    
    
       [0023]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0024]    With reference to  FIG. 1  of the drawings, a first clutch controlled decoupler constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral  10 . The clutch controlled decoupler  10  can be employed in a front engine accessory drive  12  of an internal combustion engine  14 . The front engine accessory drive  12  can include a plurality of engine accessories, such as a water pump  16 , an air conditioning compressor  18  and a starter/generator or starter/alternator  20  that can be driven by the crankshaft  22  of the engine  14  via a belt  24  and the clutch controlled decoupler  10 . Those of ordinary skill in the art will appreciate that the particular example provided pertains to a BAS (belt-alternator-starter) system because the front engine accessory drive  12  includes a starter/generator. It will be appreciated, however, that the BAS system could be equipped to additionally provide an idle-stop-accessory function in which the starter/generator is operated as an electric motor to input rotary power to (i.e., drive) the belt  24  of the front engine accessory drive  12  when the crankshaft  22  is not being driven by the engine  14 . As those of skill in the art will understand, the idle-stop-accessory function permits various accessories, such as the water pump  16  and the air conditioning compressor  18  to be operated when the engine  14  is not being operated. 
         [0025]    With reference to  FIGS. 2 through 4 , the clutch controlled decoupler  10  can comprise a decouper  30  and a clutching unit  32 . Except as described herein, the decoupler  30 , which can also be considered to be a one-way clutch, can be generally similar to the decoupler disclosed in International Patent Application No. PCT/CA2010/000296, but it will be appreciated that the decoupler  30  could be similar to any other suitable decoupler, including that which is described in U.S. Pat. No. 7,624,852. The disclosures of the aforementioned patent application and patent are incorporated by reference as if fully set forth in detail herein. 
         [0026]    The clutching unit  32  can comprise an actuator  40  and a clutch assembly  42 . The actuator  40  can comprise a coil assembly  50  and an armature  52 , while the clutch assembly  42  can include an output member or shaft member  60 , an input member or hub  62 , and a clutch element  64 . 
         [0027]    With specific reference to  FIGS. 2 and 4 , the coil assembly  50  can comprise a coil mount  70  and an annular coil  72 . The coil mount  70  can comprise an annular flange  76  and an annular coil housing  78  that can be fixedly coupled to and extend from the annular flange  76 . The annular flange  76  can be adapted to be fixedly coupled to the front cover  80  ( FIG. 1 ) of the engine  14  ( FIG. 1 ) such that a front hub  82  of the crankshaft  22  can extend therethrough. The coil  72  can be received in the coil housing  78  and can be positioned radially outwardly from the front hub  82  of the crankshaft  22 . 
         [0028]    The armature  52  can be formed of a magnetically susceptible material, such as steel, and comprise a pole member  90 , an input flange  92  and an annular spacing member  94  that can extend axially and concentrically about the coil  72 . The pole member  90  can be coupled to a first end of the spacing member  94  and can extend radially outwardly therefrom so as to be positioned axially in-line with the coil  72 . The input flange  92  can be coupled to a second, opposite end of the spacing member  94  and can extend radially inwardly therefrom. 
         [0029]    The shaft member  60  of the clutch assembly  42  can be fixedly coupled to the front hub  82  of the crankshaft  22  and can be coupled to or form an input member of the decoupler  30  (i.e., the hub spacer identified by reference numeral 30 in International Patent Application No. PCT/CA2010/000296). In the particular example provided, the shaft member  60  of the clutch assembly  42  is integrally formed with the hub spacer  100  of the decoupler  30  and comprises an annular flange  102  that is coupled to a rear side of the hub spacer  100  and an annular wall member  104  that extends rearwardly from the annular flange  102 . Threaded fasteners (not shown) can be received through the torsional vibration damper  106  and hub spacer  100  of the decoupler, and the hub  62 , and can be threadably engaged to holes  110  in the crankshaft  22  to fixedly couple both the torsional vibration damper  106  and the shaft member  60  to the crankshaft  22 . The annular wall member  104  can be disposed radially outwardly of the spacing member  94  of the armature  52 . A first bearing element  116  can be disposed between the spacing member  94  on the armature  52  and the annular wall member  104 . The first bearing element  116  can be configured to help maintain the armature  52  in an orientation that is disposed concentrically about the rotational axis of the crankshaft  22 , and/or to provide a lower friction surface on which the armature  52  may be translated. 
         [0030]    The hub  62  can comprise a mounting flange  120 , an output flange  122 , and a coupling member  124  that can extend axially and concentrically about the armature  52  and the annular flange  102 . The mounting flange  120  can be coupled to a first end of the coupling member  124  and can extend radially outwardly therefrom. The mounting flange  120  can be coupled to the pulley  130  of the decoupler  30  for rotation therewith. Any desired means may be employed for retaining the mounting flange  120  to the pulley  130 , including welds, threaded fasteners  132  and/or rivets. In some situations, it may be possible to integrally form some or all of the hub  62  with the pulley  130 . The output flange  122  can be coupled to a second, opposite end of the coupling member  124  and can extend radially inwardly therefrom so as to be positioned axially in-line with the input flange  92  of the armature  52 . 
         [0031]    The clutch element  64  can be configured to transmit rotary power from the hub  62  to the shaft member  60  and to inhibit the transmission of rotary power from the shaft member  60  to the hub  62  (i.e., the clutch element  64  can be configured to permit the transmission of rotary power between the hub  62  and the shaft member  60  in a first rotational direction and to inhibit the transmission of rotary power between the hub and the shaft member  60  in a second, opposite rotary direction). Those of skill in the art will appreciate that various types of clutch elements could be employed, including sprag clutches, synchronizers, mechanical diode clutches and roller/ramp clutches. In the particular example provided, the clutch element  64  comprises a wrap spring  140  that is mounted coaxially between the annular wall member  104  on the shaft member  60  and the coupling member  124  on the hub  62 . The wrap spring  140  can be formed of wire and can comprise a first end  142 , a second end  144 , and a plurality of wire coils  146  that can extend axially between the first and second ends  142  and  144 . The wire can have any appropriate cross-sectional shape, including a generally square or rectangular cross-sectional shape that can be configured to engage a clutch surface  150  formed on coupling member  124  of the hub  62 . The wrap spring  140  can be wound in a manner such that the coils  146  of the wrap spring  140  can expand radially when rotary power is transmitted between the hub  62  and the shaft member  60  in the first rotational direction (i.e., as when rotary power is input to the crankshaft  22  via the pulley  130 ) and can contract radially when the shaft member  60  rotates in the first rotational direction relative to the hub  62  (i.e., as when the shaft member  60  is directly driven by a source or rotary power, such as the crankshaft  22  of an engine). If desired, a lubricant may be employed to lubricate the interface between the wrap spring  140  and the clutch surface  150 , such as an oil (including “traction fluids”), grease, paste, film or coating. It will be appreciated that in some instances, it may be desirable to include one or more seals (not shown) between the several components, such as between the hub  62  and the pulley  130  or between the hub  62  and the shaft member  60 , and/or between the hub  62  and the coil mount  70 , for example, to inhibit the egress of the lubricant from the interior of the clutching unit  32  and/or to inhibit the ingress of dirt, debris and/or moisture into the interior of the clutching unit  32 . Alternatively, one or more labyrinths may be formed between the several components to generate tortuous paths by which the lubricant would need to travel to exit the interior of the clutching unit  32  and by which dirt, debris and/or moisture would need to travel to enter the interior of the clutching unit  32 . 
         [0032]    In the example provided, a carrier  160  is employed to non-rotatably couple the first end  142  of the wrap spring  140  to the shaft member  60  and a spring support or thrust ring  164  is employed to couple the second end  144  of the wrap spring  140  to the hub  62 . 
         [0033]    The wrap spring  140  and the carrier  160  can be coupled to one another in a manner that is similar to the manner in which the wrap spring and the carrier are coupled to one another in FIGS. 13 and 14 of International Patent Application No. PCT/CA2009/001660, the related disclosure of which is hereby incorporated by reference. In brief, the carrier  160  can be an annular structure or cartridge onto which the wrap spring  140  is assembled. The carrier  160  can be formed of any desired material, such as an engineering nylon, and can define an aperture  170 , a slot (not shown) and one or more lug recesses (not shown). The aperture  170  can be sized to receive the annular wall member  104  of the shaft member  60  therethrough such that the carrier  160  may be abutted axially against the annular flange  102 . The slot can be configured to receive the first end  142  of the wrap spring  140  and to orient an axial end face  180  of the wire that forms the wrap spring  140  against a corresponding face  182  formed on a lug  184  that is coupled to the shaft member  60  for rotation therewith. The lug recess(es) can be employed to inhibit or limit rotational movement of the carrier  160  relative to the shaft member  60  and/or to position the carrier  160  such that the axial end face  180  will abut the face  182  on the lug  184 . In the example provided, the shaft member  60  comprises a single lug  184  and the carrier  160  comprises a single mating lug recess that defines radially extending walls that are abutted against radially extending faces on the lug  184 ; the slot in the carrier  160  intersects one of the radially extending walls on the lug recess so that the axial end face  180  may be abutted directly against a corresponding radially extending face  182  on the lug  184 . Configuration in this manner permits rotational energy collected by the wrap spring  140  to be transmitted axially through the first end  142  of the wrap spring  140  (i.e., in a direction along the longitudinal axis of the wire that forms the first end  142  of the wrap spring  140 ) such that at least a majority of the rotational energy transmitted between the wrap spring  140  and the hub  62  exits the wrap spring  140  through the axial end face  180 . It will be appreciated, however, that the interface between the first end  142  of the wrap spring  140 , the carrier  160  and the shaft member  60  can be configured somewhat differently than that which is shown in the drawings and heretofore described in this text and that these different configurations are nonetheless within the scope of the present disclosure. For example, the first end  142  of the wrap spring  140  could be configured to transmit all or a portion of the rotational energy to the carrier  160  and the carrier  160  can be configured to transmit rotary power to the shaft member  60 . 
         [0034]    A retaining ring  190  can be mounted on the annular wall member  104  on the shaft member  60  and can limit or inhibit movement of the carrier  160  in an axial direction away from the annular flange  102 . 
         [0035]    The thrust ring  164  can be generally similar to that which is disclosed in U.S. Provisional Patent Application No. 61/432,907, the disclosure of which is incorporated by reference as if fully set forth in detail herein. The thrust ring  164  can comprise a first spacer portion  200  and a second spacer portion  202 . The first spacer portion  200  can be somewhat smaller in diameter than the clutch surface  150  and can abut the wrap spring  140  on a side opposite the carrier  160 . The side of the first spacer portion  200  that abuts the wrap spring  140  can include a helical spacer ramp  206  that can match (and thereby directly abut) the wire that forms the wrap spring  140 . If desired, the thrust ring  164  can include a feature that can receive the second end  144  of the wrap spring  140 . In the particular example provided, the second end  144  is bent or hooked radially inwardly from the coils  146  at an approximately right angle; the second end  144  is received into a mating groove (not shown) that is formed in the thrust ring  164  to inhibit rotation of the thrust ring  164  relative to the second end  144  of the wrap spring  140 . The second spacer portion  202  can be a sleeve onto which the coils  146  of the wrap spring  140  can be received. A bushing  210  may be received between the coils  146  of the wrap spring  140  and one or both of the second spacer portion  202  and the retaining ring  190  and can help to maintain the coils  146  in an orientation that is concentric about the rotational axis of the crankshaft  22 . 
         [0036]    In operation, the coil  72  is de-activated during operation of the engine such that rotational energy provided to the shaft member  60  and hub spacer  100  via the crankshaft  22  will cause corresponding rotation of the pulley  130 . Since the decoupler  30  is configured to permit relative rotation of the hub  62  (and therefore the shaft member  60 ) relative to the pulley  130  in the first rotational direction, any drag input to the wrap spring  140  (either through the coils  146  or through an interaction between the output flange  122  of the hub  62 , the input flange  92  of the armature  52 , the thrust ring  164  and the second end  144  of the wrap spring  140 ), the coils  146  of the wrap spring  140  will tend to radially contract away from and out of engagement with the clutch surface  150  on the hub  62 . Accordingly, the clutching unit  32  will not experience significant wear during operation of the engine. 
         [0037]    When it is desired to input rotary power from the pulley  130  to the crankshaft  22 , as when employing a generator or alternator to start the engine (i.e., a belt-alternator-starter or BAS system), the coil  72  can be activated or energized to generate a magnetic field that attracts the pole member  90  to thereby axially translate the armature  52 . In the example provided, the armature  52  is translated in response to the energization of the coil  72  such that the input flange  92  on the armature  52  is in driving engagement with the output flange  122  on the hub  62 . Since the thrust ring  164  is non-rotatably coupled to the armature  52  and since the second end  144  of the wrap spring  140  is non-rotatably coupled to the thrust ring  164 , rotation of the armature  52  will cause the second end  144  of the wrap spring  140  to rotate with the hub  62  in the first rotational direction to thereby cause the coils  146  of the wrap spring  140  to radially expand into driving engagement with the clutch surface  150  on the hub  62  so that the hub  62  will be driven by the hub  62  through the clutch element  64 . In this regard, rotary power is received into the wrap spring  140  via the coils  146  and is transmitted axially through the wire that forms the wrap spring  140  to the lug  184  on the shaft member  60 . In this regard, the first end  142  of the wrap spring  140  pushes against the lug  184  to drive the shaft member  60  in the first rotational direction. 
         [0038]    To provide idle-stop-accessory functionality, the coil  72  is de-activated when the starter/generator  20  ( FIG. 1 ) is operated to provide rotary power to the belt  24  ( FIG. 1 ) when the engine is not being operated. The belt  24  ( FIG. 1 ) will drive the pulley  130 . Since the decoupler  30  is configured to permit relative rotation of the hub  62  (and therefore the shaft member  60 ) relative to the pulley  130  in the first rotational direction, any drag input to the wrap spring  140  (either through the coils  146  or through an interaction between the output flange  122  of the hub  62 , the input flange  92  of the armature  52 , the thrust ring  164  and the second end  144  of the wrap spring  140 ), the coils  146  of the wrap spring  140  will tend to radially contract away from and out of engagement with the clutch surface  150  on the hub  62 . Accordingly, the clutching unit  32  will not experience significant wear during the provision of the idle-stop-accessory function. 
         [0039]    If desired, a friction material  250  may be coupled to one or both of the output flange  122  and the input flange  92  to increase the performance associated with the rotational coupling of the armature  52  to the hub  62 . 
         [0040]    With reference to  FIG. 5  of the drawings, a second clutch controlled decoupler constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral  10   a . The clutch controlled decoupler  10   a  can be employed in a front engine accessory drive  12   a  of an internal combustion engine  14   a . The front engine accessory drive  12   a  can include a plurality of engine accessories, such as a water pump  16 , an air conditioning compressor  18  and a starter/generator or starter/starter/generator  20  that can be driven by the crankshaft  22  of the engine  14  via a belt  24  and a crankshaft pulley  130   a.    
         [0041]    With reference to  FIGS. 6 and 7 , the clutch controlled decoupler  10   a  can comprise a decoupler  30   a  and a clutching unit  32   a . Except as described herein, the decoupler  30   a  can be generally similar to the decoupler disclosed in International Patent Application No. PCT/CA2009/001803, but it will be appreciated that the decoupler  30   a  could be similar to any other suitable decoupler, including those which are described in U.S. Pat. Nos. 7,618,337 and 7,591,357. The disclosures of the aforementioned patent application and patents are incorporated by reference as if fully set forth in detail herein. 
         [0042]    The clutching unit  32   a  can comprise an actuator  40   a  and a clutch assembly  42   a . The actuator  40   a  can comprise a coil assembly  50   a  and an armature  52   a , while the clutch assembly  42   a  can include an output member  60   a , an input member  62   a , and a clutch element  64   a.    
         [0043]    The coil assembly  50   a  can comprise a coil mount  70   a  and an annular coil  72   a . The coil mount  70   a  can comprise an annular coil housing  78   a  that can be coupled to a housing  310  of an alternator or starter/generator  20 . In the particular example provided, the coil housing  78   a  is received into a bore  312  that is formed in the housing  310 . The coil  72   a  can be received in the coil housing  78   a  and can be positioned radially outwardly from a shaft  316  of the starter/generator  20 . 
         [0044]    The armature  52   a  can be formed of a magnetically susceptible material, such as steel, and can comprises an annular pole member  90   a , an input flange  92   a , which can extend radially outwardly from the pole member  90   a , and a plurality of legs  330  that can extend axially from the pole member  90   a  so as to be concentrically disposed about the shaft  316  of the starter/generator  20 . 
         [0045]    The coil housing  78   a  can be constructed in a manner that is generally similar to that which is described in International Patent Application No. PCT/CA2010/001246, the disclosure of which is incorporated by reference. More specifically, the coil housing  78   a  can define a flange  122   a  that can be configured to frictionally engage the armature  52   a  to resist rotation of the armature  52   a  relative to the housing  310  of the starter/generator  20 . If desired, a friction material  250   a  may be coupled to one or both of the flange  122   a  and the input flange  92   a  to increase the performance associated with engagement of the input flange  92   a  to the flange  122   a.    
         [0046]    The output member  60   a  can be coupled to or integrally formed with the pulley  130   a  of the decoupler  30   a . In the example provided, the output member  60   a  comprises a clutch surface  150   a  that is formed on the pulley  130   a  of the decoupler  30   a . The clutch surface  150   a  can be defined by an annular groove  340  in the pulley  130   a  of the decoupler  30   a  that can be disposed radially between the (belt) grooves  342  on the exterior of the pulley  130   a  and the internal components of the decoupler  30   a , including the torsion spring  350 , the clutch spring  352 , the hub  354 , and the spring carrier  356 . A plurality of apertures  360  can be formed through the rear end of the pulley  130   a  and can intersect the annular groove  340 . The legs  330  of the armature  52   a  can be received through the apertures  360  into the groove  340 . 
         [0047]    The input member  62   a  of the clutch assembly  42   a  can be fixedly coupled to the hub  354  of the decoupler  30   a . In the particular example provided, the input member  62   a  of the clutch assembly  42   a  is an annular structure having one or more lugs or driver tabs  370  that extend radially outwardly from an annular body  372 . The annular body  372  can be received onto a necked down portion  376  on the hub  354  on a side opposite the torsion spring  350  of the decoupler  30   a . One or more of the driver tab(s)  370  can be engaged against a corresponding input tab  380  formed on the hub  354  to facilitate the transmission of rotary power from the hub  354  to the input member  370  as will be described in more detail, below. 
         [0048]    The clutch element  64   a  can be configured to transmit rotary power from the input member  62   a  to the output member  60   a  and to inhibit the transmission of rotary power from the output member  60   a  to the input member  62   a  (i.e., the clutch element  64   a  can be configured to permit the transmission of rotary power between the input member  62   a  and the output member  60   a  in a first rotational direction and to inhibit the transmission of rotary power between the input member  62   a  and the output member  60   a  in a second, opposite rotary direction). Those of skill in the art will appreciate that various types of clutch elements could be employed, including sprag clutches, synchronizers, mechanical diode clutches and roller/ramp clutches. In the particular example provided, the clutch element  64   a  comprises a wrap spring  140   a  that is mounted coaxially between the (belt) grooves  342  on the pulley  130   a  and the internal components of the decoupler  30   a , including the torsion spring  350 , the clutch spring  352 , the hub  354 , and the spring carrier  356 . The wrap spring  140   a  can be formed of wire and can comprise a first end  142   a , a second end  144   a , and a plurality of wire coils  146   a  that can extend axially between the first and second ends  142   a  and  144   a . The wire can have any appropriate cross-sectional shape, including a generally square or rectangular cross-sectional shape that can be configured to engage the clutch surface  150   a  formed on the output member  60   a . The wrap spring  140   a  can be wound in a manner such that the coils  146   a  of the wrap spring  140   a  can expand radially when rotary power is transmitted between the input member  62   a  and the output member  60   a  in the first rotational direction (i.e., as when the starter/generator  20  is employed as a motor for starting the engine  14   a  ( FIG. 5 ) through the front engine accessory drive  12   a  ( FIG. 5 ) and can contract radially when the output member  60   a  rotates in the first rotational direction relative to the input member  62   a  (i.e., as when rotary power is input to the alternator via a belt drive). If desired, a lubricant may be employed to lubricate the interface between the wrap spring  140   a  and the clutch surface  150   a , such as an oil (including “traction fluids”), grease, paste, film or coating. 
         [0049]    In the example provided, a carrier  160   a  is employed to non-rotatably couple the first end  142   a  of the wrap spring  140   a  to the input member  62   a  and a thrust ring  164   a  is employed to couple the second end  144   a  of the wrap spring  140   a  to the legs  330  of the armature  52   a.    
         [0050]    The wrap spring  140   a  and the carrier  160   a  can be coupled to one another in a manner that is similar to the manner in which the wrap spring and the carrier are coupled to one another in FIGS. 13 and 14 of International Patent Application No. PCT/CA2009/001660, the related disclosure of which is hereby incorporated by reference. In brief, the carrier  160   a  can be an annular structure or cartridge onto which the wrap spring  140   a  is assembled. The carrier  160   a  can be formed of any desired material, such as an engineering nylon, and can define an aperture  170   a , a slot (not shown) and one or more lugs  380 . The aperture  170   a  can be sized to permit the carrier  160   a  to be received into the groove  340  in the pulley  130   a  so that the carrier  160   a  may be abutted against the input member  62   a . The slot can be configured to receive the first end  142   a  of the wrap spring  140   a  and to orient an axial end face  180   a  of the wire that forms the wrap spring  140   a  against a corresponding face (not specifically shown) of one of the driver tabs  370  on the input member  62   a . In the example provided, the input member  62   a  comprises a plurality of driver tabs  370 , and the carrier  160   a  comprises a plurality of lugs  380  that are abutted in a circumferential direction against the driver tabs  370 . 
         [0051]    Configuration in this manner permits at least a majority of the rotational energy transmitted from the hub  354  to the input member  62   a  to be transmitted to the wire of the wrap spring  140   a  directly through the axial end face  180   a  of the first end  142   a  of the wrap spring  140   a ; this rotational energy can be transmitted to the pulley  130   a  through the plurality of coils  146   a  of the wrap spring  140   a  as will be discussed in more detail below. It will be appreciated, however, that the interface between the first end  142   a  of the wrap spring  140   a , the carrier  160   a  and the input member  62   a  can be configured somewhat differently than that which is shown in the drawings and heretofore described in this text and that these different configurations are nonetheless within the scope of the present disclosure. For example, the carrier  160   a  could be configured to receive all or a portion of the rotational energy from the input member  62   a , and the carrier  160   a  could be configured to transmit this rotational energy to the first end  142   a  of the wrap spring  140   a.    
         [0052]    One or more bushings  390  can be employed to control the concentricity of the carrier  160   a  about a rotational axis of the shaft  316  of the starter/generator  20 , as well as to limit forward axial movement of the carrier  160   a  relative to the shaft  316 . 
         [0053]    The thrust ring  164   a  can be generally similar to that which is disclosed in U.S. Provisional Patent Application No. 61/432,907, the disclosure of which is incorporated by reference as if fully set forth in detail herein. The thrust ring  164   a  can comprise a first spacer portion  200   a  and a second spacer portion  202   a . The first spacer portion  200   a  can be somewhat smaller in diameter than the clutch surface  150   a  and can abut the wrap spring  140   a  on a side opposite the carrier  160   a . The side of the first spacer portion  200   a  that abuts the wrap spring  140   a  can include a helical spacer ramp  76   a  that can match (and thereby directly abut) the wire that forms the wrap spring  140   a . If desired, the thrust ring  164   a  can include a feature that can receive the second end  144   a  of the wrap spring  140   a . In the particular example provided, the second end  144   a  is bent or hooked radially inwardly from the coils  146   a  at an approximately right angle; the second end  144   a  is received into a mating groove (not shown) that is formed in the thrust ring  164   a  to inhibit rotation of the thrust ring  164   a  relative to the second end  144   a  of the wrap spring  140   a . The second spacer portion  202   a  can be a sleeve onto which the coils  146   a  of the wrap spring  140   a  can be received. 
         [0054]    In operation, the coil  72   a  is de-activated during operation of the starter/generator  20  in a first or electric power generating mode in which rotational energy is transmitted from a belt drive (not shown) into the pulley  130   a  for driving the shaft  316 . Since the clutching unit  32   a  is configured to permit relative rotation of the output member  60   a  (and therefore the pulley  130   a ) relative to the input member  62   a  (and therefore the hub  502 ) in the first rotational direction, any drag input to the wrap spring  140   a  during operation of the starter/generator  20  in the first mode will cause the coils  146   a  of the wrap spring  140   a  to radially contract away from and out of engagement with the clutch surface  150   a  on the output member  60   a . Accordingly, the clutching unit  32   a  will not experience significant wear during operation of the starter/generator  20  in the first mode. 
         [0055]    When it is desired to operate the alternator in a second mode that provides a rotary output to the belt drive via the pulley  130   a , (i.e., as for providing rotary power for the starting of an internal combustion engine in a belt-alternator-starter or BAS system), the coil  72   a  can be activated or energized to generate a magnetic field that attracts the pole member  90   a  to thereby axially translate the armature  52   a . In the example provided, the armature  52   a  is translated in response to the energization of the coil  72   a  such that the input flange  92   a  on the armature  52   a  frictionally engages the flange  122   a  on the coil housing  78   a  to thereby resist rotation of the armature  52   a  relative to the shaft  316  of the starter/generator  20 . Simultaneously, operation of the starter/generator  20  in the second mode will cause rotation of the shaft  316 , thereby causing rotation of the input member  62   a , which in turn introduces rotational energy into the wrap spring  140   a  that would tend to cause the coils  146   a  of the wrap spring  140   a  to enlarge in a radial direction (to thereby drivingly engage the clutch surface  150   a  on the output member  60   a ). Since the thrust ring  164   a  is non-rotatably coupled to the armature  52   a  and since the second end  144   a  of the wrap spring  140   a  is non-rotatably coupled to the thrust ring  164   a , operation of the coil  72   a  to cause the armature  52   a  to resist rotation will correspondingly impede rotation of the second end  144   a  of the wrap spring  140   a . Non-rotation or impeded rotation of the second end  144   a  of the wrap spring  140   a  relative to the first end  142   a  of the wrap spring  140   a  ensures that torsion will be transmitted through the wrap spring  140   a  to a degree that causes the coils  146   a  of the wrap spring  140   a  to drivingly engage the clutch surface  150   a  to thereby transmit rotary power that is received from the input member  62   a  to the output member  60   a  (and thereby to the pulley  130   a ). As will be appreciated, rotational energy received by the wrap spring  140   a  from the input member  62   a  can be transmitted axially through the first end of the wrap spring  140   a  to the plurality of coils  146   a , and through a plurality of the coils  146   a  to the clutch surface  150   a.    
         [0056]    It will be appreciated that the clutching unit  32  ( FIG. 2 ) of the present disclosure can have various other uses, including as a selectively operable clutch for operating an engine accessory. With reference to  FIG. 8 , a clutching unit  32   b  is illustrated in operative association with an engine accessory, such as a cooling fan. The clutching unit  32   b  can be generally similar to that which is described in  FIG. 1 , with the input member  60   b  being coupled to the cooling fan pulley  130   b  for rotation therewith and the output member  62   b  being coupled to the cooling fan (not shown). 
         [0057]    It will also be appreciated from this disclosure that the clutch unit  32  ( FIG. 2 ) may be incorporated into various other devices. For example, the clutch unit  32  ( FIG. 2 ) could be substituted for the clutch assembly that is disclosed in one or more of the examples described in International Patent Application No. PCT/CA2009/001660, the disclosure of which is incorporated by reference. 
         [0058]    As noted above, various different types of one-way clutches could be employed in lieu of the wrap spring clutch that is depicted in the above examples. With reference to  FIGS. 9 through 11 , a second clutch controlled decoupler constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral  10   b . The clutch controlled decoupler  10   b  is generally similar to the clutch controlled decoupler  10  of  FIG. 2  except that a roller clutch is substituted for the wrap spring clutch that is employed in the above-described example. The roller clutch  500  can include a hub  502 , a cage  504 , a plurality of cylindrical rollers  506 , a shaft  508 , an armature  510 , a friction liner  512  and a coil assembly  50   b  that can be fixedly and non-rotatably coupled to the structure of an engine structure, such as an engine cover (not shown). The hub  502  can be coupled for rotation with the pulley  130  of the decoupler  30   b  and can include a plurality of outer tracks or raceways  520 . Each outer track  520  can have a first track portion  522  and a second track portion  524 . The cage  504  can define a plurality of holders  526 , each of which being configured to receive an associated one of the rollers  506 . The shaft  508  can include a shaft portion  530  and a flange  532 . The shaft portion  530  can be non-rotatably coupled to the crankshaft (not shown) of an engine (not shown), while the flange  532  can be coupled to the cage  504  in a manner that permits limited rotational movement of the cage  504  relative to the flange  532 . In the particular example provided, the cage  504  includes a plurality of legs  534  that extend through slotted apertures  536  formed through the flange  532 . A thrust bearing  538  can be received between the flange  532  and the hub  502 . The rollers  506  can be received in the holders  526  and can engage the outer tracks  520  and the shaft portion  530 . Rotation of the cage  504  relative to the hub  502  can move the rollers  506  between the first and second track portions  522  and  524 . When the rollers  506  are in the first track portions  522 , the rollers  506  permit relative rotation between the shaft portion  550  and the hub  502 . When the rollers  506  are in the second track portions  524 , the rollers  506  are wedged between the hub  502  and the shaft portion  530  to thereby inhibit relative rotation between the hub  502  and the shaft portion  530 . 
         [0059]    The friction liner  512  can be an annular structure that can be fixedly and non-rotatably coupled to the legs  534  of the cage  504 . The friction liner  512  can be slidably received on the shaft portion  530  between the armature  510  and the flange  532 . The armature  510  can be axially slidably but non-rotatably mounted on the coil assembly  50   b . The armature  510  can be moved in an axial direction by operation of the coil assembly  50   b . In the particular example provided, the coil assembly  50   b  can be operated to drive the armature  510  away from the coil assembly  50   b  and to frictionally engage the friction liner  512  to the legs  534  to create a drag force that can cause the cage  504  to rotate relative to the hub  502  so that the rollers  506  are moved from the first track portion  522  to the second track portion  524 . It will be appreciated that the friction liner  512  could be biased by a spring (not shown), such as a leaf spring, into or out of engagement with the legs  534 . 
         [0060]    It will be appreciated that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the teachings of the present disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Listing of Elements 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 clutch controlled decoupler 
                  10 
               
               
                   
                 clutch controlled decoupler 
                  10a 
               
               
                   
                 clutch controlled decoupler 
                  10b 
               
               
                   
                 engine accessory drive 
                  12 
               
               
                   
                 engine accessory drive 
                  12a 
               
               
                   
                 engine 
                  14 
               
               
                   
                 engine 
                  14a 
               
               
                   
                 water pump 
                  16 
               
               
                   
                 air conditioning compressor 
                  18 
               
               
                   
                 starter/generator 
                  20 
               
               
                   
                 crankshaft 
                  22 
               
               
                   
                 belt 
                  24 
               
               
                   
                 decoupler 
                  30 
               
               
                   
                 decoupler 
                  30a 
               
               
                   
                 decoupler 
                  30b 
               
               
                   
                 clutching unit 
                  32 
               
               
                   
                 clutching unit 
                  32a 
               
               
                   
                 clutching unit 
                  32b 
               
               
                   
                 actuator 
                  40 
               
               
                   
                 actuator 
                  40a 
               
               
                   
                 clutch assembly 
                  42 
               
               
                   
                 clutch assembly 
                  42a 
               
               
                   
                 coil assembly 
                  50 
               
               
                   
                 coil assembly 
                  50a 
               
               
                   
                 coil assembly 
                  50b 
               
               
                   
                 armature 
                  52 
               
               
                   
                 armature 
                  52a 
               
               
                   
                 shaft member 
                  60 
               
               
                   
                 output member 
                  60a 
               
               
                   
                 input member 
                  60b 
               
               
                   
                 hub 
                  62 
               
               
                   
                 input member 
                  62a 
               
               
                   
                 clutch element 
                  64 
               
               
                   
                 clutch element 
                  64a 
               
               
                   
                 coil mount 
                  70 
               
               
                   
                 coil mount 
                  70a 
               
               
                   
                 coil 
                  72 
               
               
                   
                 coil 
                  72a 
               
               
                   
                 annular flange 
                  76 
               
               
                   
                 spacer ramp 
                  76a 
               
               
                   
                 coil housing 
                  78 
               
               
                   
                 coil housing 
                  78a 
               
               
                   
                 front cover 
                  80 
               
               
                   
                 front hub 
                  82 
               
               
                   
                 pole member 
                  90 
               
               
                   
                 pole member 
                  90a 
               
               
                   
                 input flange 
                  92 
               
               
                   
                 input flange 
                  92a 
               
               
                   
                 spacing member 
                  94 
               
               
                   
                 hub spacer 
                 100 
               
               
                   
                 annular flange 
                 102 
               
               
                   
                 annular wall member 
                 104 
               
               
                   
                 torsional vibration damper 
                 106 
               
               
                   
                 holes 
                 110 
               
               
                   
                 first bearing element 
                 116 
               
               
                   
                 mounting flange 
                 120 
               
               
                   
                 output flange 
                 122 
               
               
                   
                 flange 
                 122a 
               
               
                   
                 coupling member 
                 124 
               
               
                   
                 pulley 
                 130 
               
               
                   
                 pulley 
                 130a 
               
               
                   
                 pulley 
                 130b 
               
               
                   
                 wrap spring 
                 140 
               
               
                   
                 wrap spring 
                 140a 
               
               
                   
                 first end 
                 142 
               
               
                   
                 first end 
                 142a 
               
               
                   
                 second end 
                 144 
               
               
                   
                 second end 
                 144a 
               
               
                   
                 wire coils 
                 146 
               
               
                   
                 wire coils 
                 146a 
               
               
                   
                 clutch surface 
                 150 
               
               
                   
                 clutch surface 
                 150a 
               
               
                   
                 carrier 
                 160 
               
               
                   
                 carrier 
                 160a 
               
               
                   
                 thrust ring 
                 164 
               
               
                   
                 thrust ring 
                 164a 
               
               
                   
                 aperture 
                 170 
               
               
                   
                 aperture 
                 170a 
               
               
                   
                 axial end face 
                 180 
               
               
                   
                 axial end face 
                 180a 
               
               
                   
                 face 
                 182 
               
               
                   
                 lug 
                 184 
               
               
                   
                 retaining ring 
                 190 
               
               
                   
                 first spacer portion 
                 200 
               
               
                   
                 first spacer portion 
                 200a 
               
               
                   
                 second spacer portion 
                 202 
               
               
                   
                 second spacer portion 
                 202a 
               
               
                   
                 spacer ramp 
                 206 
               
               
                   
                 bushing 
                 210 
               
               
                   
                 friction material 
                 250 
               
               
                   
                 friction material 
                 250a 
               
               
                   
                 housing 
                 310 
               
               
                   
                 bore 
                 312 
               
               
                   
                 shaft 
                 316 
               
               
                   
                 legs 
                 330 
               
               
                   
                 annular groove 
                 340 
               
               
                   
                 belt grooves 
                 342 
               
               
                   
                 torsion spring 
                 350 
               
               
                   
                 clutch spring 
                 352 
               
               
                   
                 hub 
                 354 
               
               
                   
                 spring carrier 
                 356 
               
               
                   
                 apertures 
                 360 
               
               
                   
                 driver tabs 
                 370 
               
               
                   
                 annular body 
                 372 
               
               
                   
                 input tab 
                 380 
               
               
                   
                 bushing 
                 390 
               
               
                   
                 roller clutch 
                 500 
               
               
                   
                 hub 
                 502 
               
               
                   
                 cage 
                 504 
               
               
                   
                 rollers 
                 506 
               
               
                   
                 shaft 
                 508 
               
               
                   
                 armature 
                 510 
               
               
                   
                 friction liner 
                 512 
               
               
                   
                 outer tracks 
                 520 
               
               
                   
                 first track portion 
                 522 
               
               
                   
                 second track portion 
                 524 
               
               
                   
                 holders 
                 526 
               
               
                   
                 shaft portion 
                 530 
               
               
                   
                 flange 
                 532 
               
               
                   
                 legs 
                 534 
               
               
                   
                 slotted apertures 
                 536 
               
               
                   
                 thrust bearing 
                 538