Patent Publication Number: US-2023151855-A1

Title: Clutch ring and differential with a clutch

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 63/278,823 filed Nov. 12, 2021. The entire content of this priority application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a clutch ring and a vehicle driveline component, such as a differential, with a clutch having a clutch ring. 
     BACKGROUND 
     A vehicle driveline transfers motive power to vehicle wheels. Various driveline components are known. For example, power transfer units are commonly utilized in front-wheel drive based all-wheel drive systems. Power transfer units may include a disconnect device so that power is transferred to only the front wheels during certain vehicle operating conditions and to more and up to all wheels in other vehicle operating conditions. Vehicle drivelines may also include differentials that allow the wheels to spin at different rates while transmitting torque to the wheels. 
     Some of these driveline devices include a clutch that permits selective torque transfer through the device. The clutch may be driven by an electromagnetic actuator to drive the clutch between engaged and disengaged states. Engaging, disengaging and handling torque requirements can be challenging in designs requiring, for example, reduced weight and/or smaller part sizes. 
     SUMMARY 
     In at least some implementations, a clutch member includes a main body having a central axis, a radially inner surface, a radially outer surface, a rear face and a front face, multiple teeth formed in the front face with adjacent teeth circumferentially spaced apart, and a rim extending axially from the main body and located radially outwardly of the teeth. The rim extends axially farther from the rear face than do the teeth. 
     In at least some implementations, the main body includes multiple feet that extend axially from the rear face. In at least some implementations, the rim is circumferentially continuous. In at least some implementations, a radially outer surface of the rim is radially aligned with and defines part of the outer surface of the main body. In at least some implementations, a front surface of the rim extends radially and circumferentially, and is planar and either: a) perpendicular to the central axis, or b) inclined at an angle that is 45 degrees or less to a plane perpendicular to the central axis. 
     In at least some implementations, the teeth are defined between adjacent grooves formed in the front face. In at least some implementations, the grooves extend to a radially inner surface of the rim. In at least some implementations, a radially extending intermediate surface is located between the teeth and the rim. 
     In at least some implementations, the rim extends axially beyond by an amount up to five times the thickness of the rim, where the thickness of the rim is the radial dimension of the rim. In at least some implementations, the axial extent of the rim is equal to or less than the axial extent of a radially outer surface of the main body from the rear face to the front face of the teeth. 
     In at least some implementations, a rotary power transmission device includes a housing having an interior in which multiple gears are received for rotation, an actuator having a plunger driven for movement along an axis of the plunger between advanced and retracted positions and a clutch assembly, The clutch assembly includes a clutch ring having a front face and a rear face opposite the front face, the front face including teeth selectively engageable with teeth of one of the gears, the clutch ring being driven by the plunger between a first position in which the teeth of the clutch ring are engaged with the teeth of the gear, and a second position in which the teeth of the clutch ring are not engaged with the teeth of the gear, and the clutch ring includes a rim extending axially from the main body and located radially outwardly of the teeth, the rim extending axially farther from the rear face than do the teeth. 
     In at least some implementations, the main body includes multiple feet that extend axially from the rear face. In at least some implementations, the teeth are defined between adjacent grooves formed in the front face. In at least some implementations, the grooves extend to a radially inner surface of the rim. In at least some implementations, a radially extending intermediate surface is located between the teeth and the rim. 
     In at least some implementations, the rim is circumferentially continuous. In at least some implementations, a radially outer surface of the rim is radially aligned with and defines part of the outer surface of the main body. In at least some implementations, a front surface of the rim extends radially and circumferentially, and is planar and either: a) perpendicular to the central axis, or b) inclined at an angle that is 10 degrees or less to a plane perpendicular to the central axis. In at least some implementations, the rim extends axially beyond the teeth by an amount up to five times the thickness of the rim, where the thickness of the rim is the radial dimension of the rim. In at least some implementations, the multiple gears include a side gear and a pinion gear that are mated together, and the side gear rotates about the central axis and the rim axially overlaps a portion of the side gear in the both the first position and the second position of the clutch ring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of preferred embodiments and best mode will be set forth with reference to the accompanying drawings, in which: 
         FIG.  1    is a schematic diagram of a vehicle driveline assembly; 
         FIG.  2    is a cross-sectional view of a differential with an electrically actuated clutch, wherein the differential is shown in an open position; 
         FIG.  3    is a fragmentary sectional view of a portion of the clutch showing a clutch ring; 
         FIG.  4    is a fragmentary sectional view of a portion of the clutch showing a clutch ring; 
         FIG.  5    is a perspective view of the back of the clutch ring; 
         FIG.  6    is a perspective view of the front of the clutch ring; 
         FIG.  7    is an enlarged perspective view of part of the clutch ring; and 
         FIG.  8    is an enlarged perspective view of part of a second clutch ring. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIG.  1    illustrates a vehicle driveline  12  that provides power from an engine  14  to multiple wheels including front wheels  15  and rear wheels  16 . The engine  14  supplies torque via a transmission  17  and a power transfer unit  18  that provides an output shaft  20 . The output shaft  20  is coupled to a first prop shaft  21  which is coupled to a rear drive unit  22  that may include a differential assembly  23 . The power transfer unit  18  or other device may have an output shaft  24  coupled to a front drive unit  25  (which may include a differential assembly  26 ) via a second prop shaft  27 . Front left and right side shafts  28 ,  29  are coupled to the drive unit/differential  25 ,  26  which permits relative rotation between the side shafts  28 ,  29  and front wheels  15 . Rear left and right side shafts  30 ,  32  are coupled to the rear drive unit/differential  22 ,  23  which permits relative rotation between the side shafts  30 ,  32  and rear wheels  16 . The power transfer unit  18  may include a disconnect assembly that, when in a connected state, transfers torque to the second prop shaft  27  to drive the front wheels  15 . When connected or disconnected, the power transfer unit  18  may provide torque to the first prop shaft  21  to drive the rear wheels  16 . Thus, depending upon the state of the disconnect device, the driveline  12  may provide torque to the rear wheels  16  only or to all four of the wheels  15 ,  16 . Of course, other driveline configurations may be used, as desired. 
     Referring now to  FIG.  2   , the first rear side shaft  30  is connected to a first side gear  34  within the differential  23 . Similarly, the second rear side shaft  32  is connected to a second side gear  36  within the differential  23 . The side gears  34 ,  36  are carried within a housing  37  of the differential  23 . The differential also includes pinion gears  38 ,  40  that are meshed with side gears  34 ,  36 , respectively, and which are mounted within the housing  37  on a pinion shaft  42 . 
     To selectively lock and unlock the differential  23  a clutch assembly  46  is provided. The clutch assembly  46  may have actuated and deactuated states, and in one state the clutch assembly couples one of the side shafts (e.g.  32 ) to the differential housing  37  so that the coupled side shaft rotates with the housing. This, in turn, causes the other side shaft  30  to rotate in unison with the housing  37  and the side shaft  32  coupled to the housing so that both side shafts  30 ,  32  rotate at the same speed. 
     In at least some implementations, the clutch assembly  46  is electrically actuated and includes a solenoid  48  having an annular wire coil  49  and a drive member that may include an armature or plunger  54  received at least partially radially inwardly of and axially overlapped with the coil. In at least some implementations, the plunger  54  is also annular, the plunger and coil  49  are coaxially arranged and carried by the housing  37  for rotation with the housing, and one side shaft (here, the second side shaft  32 ) extends coaxially through a portion of the housing  37  that extends through the coil and plunger. Electric power is supplied to the coil  49  via a power wire  50  to generate a magnetic field that displaces the plunger  54  relative to the coil and differential housing  37  from a first or retracted position to a second or advanced position. To facilitate return of the plunger  54  from the second position back to the first position when power is not provided to the coil  49 , a biasing member, such as a spring  55  may act on the plunger  54 , or on a component engaged with the plunger, as set forth below. In at least some implementations, the clutch assembly  46  is actuated when the plunger  54  is in the second position and the clutch assembly is deactuated when the plunger is in the first position. While in the example shown the plunger  54  is in its second position when power is provided to the coil  49  and the plunger moves to the first position when power is not supplied to the coil, the opposite could be true if desired (e.g. the clutch assembly  46  could be moved to the actuated position by the biasing member  55  and deactuated by powering the coil). 
     In at least some implementations, the clutch assembly  46  may further include or be associated with a clutch member, called herein a clutch ring  56  adapted to be driven by the plunger  54  and to interface with the side gear  34  as set forth below. The clutch ring  56  may be annular and a portion of the second side gear  36  and/or shaft  32  may extend through the clutch ring. The clutch ring  56  may include a rear face  57  engageable by the plunger  54  and a front face  59  having at least one engagement feature  58 , such as gear or clutch teeth  58  (e.g. dog clutch teeth) configured to engage a corresponding engagement feature  60  (e.g. gear or dog clutch teeth) formed on a rear face of the first side gear  34 . The spring  55  may act on the clutch ring  56  to urge the clutch ring into the plunger  54  and move the plunger to its first position when the coil  49  is not powered, as noted above. In the implementation shown, the plunger  54  is located adjacent to one side of a housing wall  62  and the clutch ring  56  is located adjacent to the other side of the wall  62 . The wall  62  includes apertures  64 , and the plunger  54  and clutch ring  56  include axially extending feet  66 ,  68  (e.g.  FIGS.  2  and  3   ), respectively, that extend into or through the apertures  64  in the wall so that the plunger and clutch ring are engaged with each other across or through the wall. Like the coil  49  and plunger  54 , the clutch ring  56  also is carried by and rotates with the housing  37 . 
     The differential  23  illustrated in  FIG.  2    is shown in an open mode or position. In the illustrated implementation, in the open position of the differential, the coil  49  is not powered, the plunger  54  is in its first position and the clutch ring  56  is not engaged with the side gear  34  so that the side gear can rotate relative to the clutch ring  56  and housing  37 . In the open position, the side shafts  30 ,  32  may rotate at different speeds from one another. However, certain driving conditions may make it desirable for the side shafts  30 ,  32  to rotate in unison such that torque is applied to both wheels. 
     In the locked position, the coil  49  is powered, the plunger  54  is advanced to its second position which drives the clutch ring  56  into engagement with the side gear  34  (i.e. teeth  58  engage and mesh with teeth  60 ). Hence, the side gear  34  is coupled to the housing  37  so that the side gear rotates with and not relative to the housing. In effect, the second side shaft  32  is locked to and rotates with the housing  37 , which in turn forces the first side shaft  30  and the second side shaft  32  to rotate in unison. 
     As shown in  FIGS.  2 - 8  and  10   , the plunger  54  may be formed from multiple materials including a material that is magnetically responsive to the magnetic field generated by the coil  49 , and at least one other material that may or might not be responsive to the magnetic field. Thus, when the magnetic field is generated by the coil  49 , the plunger  54  may be driven from one position to another (e.g. from the retracted to the advanced position). As used herein, a material is responsive to a magnetic field if a magnetic field of the magnitude generated by a solenoid  48  of the type used in applications such as that described herein, may cause a component formed of or including such material to be displaced. 
     In at least some implementations, as shown in  FIG.  3   , the plunger  54  includes a main body  72  with a central axis  73  and which may be defined by a first body  74  and a second body  76  that are coupled together and move as one unit or component and are not separated during use. The first body  74  may be formed from a magnetically responsive material and may be received adjacent to and radially inwardly of the coil  49 , with a small air gap between them. The second body  76  may have at least a portion that is radially inward of at least a portion of the first body  74 . The second body  76  may be annular and may, in at least some implementations, radially overlap part of the first body  74 . The second body  76  may be conveniently overmolded onto the first body  74  to facilitate forming the second body and connecting together the first and second bodies, however other forming processes such as but not limited to casting, stamping or extruding may be used. The second body  76  may define part or all of the feet  66  of the plunger  54  which may extend axially beyond the first body  74 , if desired. The second body  76  may be formed from a material that is not magnetically responsive (e.g. plastic, aluminum, stainless steel, etc.), and may provide a magnetic flux shield of sorts that improves the magnetic field strength on or in the area of the first body  74  to ensure proper response of the plunger  54  when the coil  49  is energized. In this way, the magnetic field is more concentrated or stronger in the area of the first body  74  to increase the magnetic flux at or in the first body and improve the responsiveness of the plunger  54  to the generated magnetic field. 
     As shown in  FIG.  2   , the second body  76  may have an inner surface  78  that is received adjacent to or around a surface  79  of the differential housing  37 . The inner surface  78  may define a pilot diameter for receipt of the plunger  54  over the annular surface  79  of the differential housing  37  for guided linear, axial movement of the plunger relative to the differential housing. 
     Referring to  FIGS.  5  and  6   , the clutch ring  56  has a main body  80  with a central axis  82  which may be coaxial with the axis  73  of the plunger  54 , a radially outer surface  84  that extends axially between the rear face  57  ( FIG.  5   ) and the front face  59  ( FIG.  6   ), and a radially inner surface  86  that may have a lesser axial extent than the outer surface  84 . The inner surface  86  of the clutch ring  56  may be received around a surface of the side gear  34 , as shown in  FIGS.  2 - 4   . The feet  68  of the clutch ring  56  are circumferentially spaced apart and extend axially from the rear face  57 , and the teeth  58  are located on the front face  59 . The clutch ring  56  may be made from metal, such as alloy steel, chromium steel, chromium molybdenum steel, nickel steel, nickel chromium molybdenum steel, mid/high carbon steel, etc. 
     As shown in  FIGS.  6  and  7   , the clutch ring teeth  58  are separated from each other and defined at least in part by grooves  88  formed in the front face  59 , arranged at even intervals in the circumferential direction, and with each tooth  58  located circumferentially between two grooves  88 . The teeth  58  extend radially from a radially inner edge  90  to a radially outer edge  92 . The teeth  58  have opposite, circumferentially spaced apart side surfaces  94  that extend axially and radially between the inner edge  90  and outer edge  92 , and the teeth  58  have front faces  96  that extend radially and circumferentially between the inner edge  90  and outer edge  92 . So arranged, each groove  88  extends radially and circumferentially between two adjacent teeth  58 , and the grooves have a bottom wall  95  that may be parallel to and recessed relative to the front face  96  of the teeth  58 , and the grooves  88  have an end wall  97  at the radially outer end of the grooves  88 . The radial distance between the inner edge  90  and outer edge  92  defines a length of each tooth  58 , the circumferential extent between the side surfaces  94  defines a width of each tooth  58 , and the axial extent of the side surfaces  94  defines a thickness of each tooth  58 . With radially oriented sides, the width of each tooth  58  varies along its length, and increases from the inner edge  90  to the outer edge  92 . Further, the side surfaces  94  may be radially oriented so that the front face  96  of each tooth  58  is less wide than is a base of each tooth that is opposite the front face  96  and which joins the main body  80  (e.g. at the bottom of the adjacent grooves  88 ). In at least some implementations, the front faces  96  of the teeth  58  may lie in a common plane, that is, each tooth  58  may have the same thickness along its length, and each tooth  58  may have the same thickness as the other teeth. The plane may be perpendicular to the central axis  82 . 
     In at least some implementations, the inner edges  90  of the teeth  58  are radially outwardly spaced from the inner surface  86  of the main body  80 , and the inner surface  86  of the main body  80  defines a minimum diameter of the clutch ring  56  and does not axially overlap the teeth  58 . In such an arrangement, an annular, radially extending and axially recessed surface  98  extends from an edge  100  of the inner surface  86  of the main body  80  to the base of the inner edge  90  of the teeth  58 . This surface  98  may be engaged by the spring  55 , which may be received between this surface  98  and an opposed surface of the side gear  34 . Of course, other arrangements are possible and the teeth  58  may extend to the inner surface  86  of the main body  80  or be otherwise shaped, as desired. 
     Radially outwardly of the outer edge  92  of the teeth  58 , the clutch ring  56  may include a rim  102 . In at least some implementations: a radially inner surface  104  of the rim  102  extends radially from or adjacent to the outer edge  92  of the teeth  58  to the outer surface  84  of the main body  80 ; an outer surface  106  of the rim  102  may be radially aligned with and define part of the outer surface  84  of the main body  80 ; the rim  102  may be circumferentially continuous; and a front surface  108  of the rim  102  is axially farther from the rear face  57  of the clutch ring  56  than are the front faces  96  of the teeth  58 . The front surface  108  of the rim  102  extends radially and circumferentially, and may be planar and perpendicular to the central axis  82 , or inclined at an angle that is 45 degrees or less to a plane perpendicular to the central axis. 
     So arranged, the rim  102  extends axially forward of the teeth  58 , and when the clutch ring  56  is assembled into the differential  23 , the rim  102  extends axially farther toward the side gear  34  than do the teeth  58  of the clutch ring  56 . With the rim  102 , the clutch ring  56  is stronger than a clutch ring  56  lacking an axially extending rim  102 . In use of the device, significant stresses occur at the base  110  (shown in  FIG.  5   ) of the feet  68  on the rear face  57  of the clutch ring  56 , at the radiused transition from the feet  68  to the rear face  57  of the clutch ring  56 , with highest stress levels often occurring near the radially inner edge  112  of the base  110  of the feet  68 . These stresses can be reduced and better accommodated by the stronger clutch ring  56  with the axially extending rim  102  without having to increase the axial thickness of the main body  80  of the clutch ring  56 . This makes the clutch ring  56  more durable and also enables the clutch ring  56  to fit within a smaller area of the housing  37  and to be lighter than a clutch ring  56  with an axially thicker main body. This also enables the clutch ring  56  to be used in higher torque applications without a corresponding increase in the size and weight of the clutch ring  56 . In one such clutch ring  56  with an axially extending rim  102 , the stresses at the base  110  of the feet  68  were reduced by over 20% compared to a clutch ring without the axially extending rim  102 . 
     In at least some implementations, the rim  102  may axially overlap (and be radially outward of) a portion of the side gear  34  in both the first position and second position of the clutch ring  56 . That is, as shown in  FIGS.  3  and  4   , when engaged with the side gear  34  and when disengaged from the side gear  34 , the rim  102  may axially overlap part of the side gear  34 . This overlap creates a space  114  between the rim  102  and the side gear  34  and lubrication within the housing  37  may enter this space  114  and be retained by the rim  102  to enhance lubrication of the front face  59  of the clutch ring  56 , the opposed face of the side gear  34  and adjacent components such as the spring  55 . 
     The rim  102  may extend into an area  116  between the side gear  34  and the housing  37 , and beyond an adjacent surface  118  of the housing  37  that provides a minimum radial clearance between the housing  37  and the clutch ring  56 , and by which the axial movement of the clutch ring  56  may be guided (such movement could also or instead by guided by the radially inner surface of the clutch ring). In this way, a gap  120  greater in radial dimension than the minimum radial clearance between the housing  37  and the clutch ring  56  is defined between the rim  102  and part of the housing  37 . This gap  120  exists at least when the clutch ring teeth  58  are engaged with the side gear teeth  60 , and may also exist when the clutch ring  56  is disengaged from the side gear  34 , as shown in  FIGS.  3  and  4   . Some lubrication within the housing  37  may collect in that gap  120  and may flow between the outer surface  84  of the clutch ring  56  and the housing surface  18 , to improve lubrication of the clutch ring  56  and facilitate movement of the clutch ring  56  relative to the housing  37 . Further, the increased axial length of the outer surface  84  of the clutch ring  56  provides a longer guide surface for axial movement of the clutch ring  56  and reduces any tilting of the clutch ring  56  to maintain the clutch ring coaxial with the side gear  34  and the front face  59  of the clutch ring  56  perpendicular to the axis  82 . In at least some implementations, the outer surface  84  of the main body  56  may be longer axially than is the surface  118  of the housing  37  that provides the minimum radial clearance between the housing  37  and the outer surface  84  of the clutch ring  56 . 
     In the example shown in  FIGS.  6  and  7   , the grooves  88  between the teeth  58  do not extend to the radially inner surface  104  of the rim  102  and an annular, radially extending intermediate surface  122  is located between the teeth  58  and the rim  102 . In the example clutch ring  56 ′ shown in  FIG.  8   , the grooves  88 ′ between the teeth  58 ′ extend all the way to the radially inner surface  104 ′ of the rim  102 ′, and the grooves  88 ′ also extend axially to the front surface  108 ′ of the rim  102 ′. The radially inner surface  104 ′ of the rim  102 ′, in at least some implementations, varies in its radial distance from the central axis  82  with portions of the inner surface  104 ′ defined by the grooves  88 ′ being radially farther from the axis  82  than portions of the inner surface  104 ′ radially aligned with the teeth  58 ′. Stated differently, each groove  88 ′ has a radially outer end  124  that extends axially from the front surface  108 ′ of the rim  102 ′ to the radially extending base  95 ′ of the groove  88 ′ between adjacent teeth  58 ′. In this example, the front faces  96 ′ of the teeth  58 ′ may merge, at the radially outer edge  92 ′ of the front faces  96 ′, with the inner surface  104 ′ of the rim  102  which extends axially to the front faces  96 ′ of the teeth  58 ′ in the areas of the rim  102 ′ aligned with the teeth  58 ′. The radially outer end  124  of the grooves  88 ′ define side surfaces  94 ′ of the teeth  58 ′ that extend radially farther from the axis  82  than do the front faces  96 ′ of the teeth  58 ′ and axially along the portions of the inner surface  104 ′ of the rim  102 ′ that are radially aligned with the teeth  58 ′. The cam ring  56 ′ may be used and may function in the same way as the cam ring  56 . 
     In at least some implementations, the rim  102 ,  102 ′ may extend axially beyond the teeth  58 ,  58 ′ by an amount up to five times the thickness of the rim, and in some implementations, between two and five times, where the thickness is the radial dimension of the rim (e.g. outer diameter minus inner diameter). The inner diameter may be measured at the base of the rim or at the radially outer edge  92 ,  92 ′ of the teeth  58 ,  58 ′ (e.g. the inner diameter may include a surface like the intermediate surface  122 ). The extent to which the rim  102 ,  102 ′ extends axially beyond the teeth  58 ,  58 ′ may be limited by adjacent components wherein the rim  102 ,  102 ′ may be sized so as to not engage adjacent components as the clutch ring  56 ,  56 ′ moves in use. In at least some implementations, the axial extent of the rim  102 ,  102 ′ may be equal to or less than the axial extent of the outer surface  84  from the rear face  57  to the front face  96 ,  96 ′ of the teeth  58 ,  58 ′. Further, the rim  102 ,  102 ′ may have any desired radial thickness that fits within the area in which the clutch ring  56 ,  56 ′ is received. That is, without undue interference to movement of the clutch ring  56 ,  56 ′ due to engagement with a component at the radial outer and inner surfaces  84 ,  86  of the clutch ring. 
     Although the above descriptions relate to a locking differential device, other rotary power transmission devices, such as power take-off units or axle disconnects, could utilize a clutch with a clutch ring as described herein. Further, the forms of the invention herein disclosed constitute presently preferred embodiments and many other forms and embodiments are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention. 
     All terms used in the claims are intended to be given their broadest reasonable construction and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.