Abstract:
A wedge clutch assembly for transferring torque from an engine to an output shaft, comprising a clutch carrier comprising an axial friction surface and a radially inwardly facing surface, a hub comprising a first radially outwardly facing surface having grooves positioned circumferentially thereon and detents positioned within the grooves, a wedge plate comprising an axial friction surface, a second radially outwardly facing surface, and a second radially inwardly facing surface having recesses, a pressure plate concentrically arranged within the first radially inwardly facing surface and displaceable such that in an engaged mode, an axial force is applied to the pressure plate, in a first axial direction, to engage the wedge plate with the clutch carrier such that torque is transferred from the engine to the output shaft, and in a disengaged mode, the wedge plate is independently rotatable from the clutch carrier.

Description:
FIELD 
       [0001]    The present disclosure relates generally to clutch discs, more particularly to a wedge clutch assembly having detents. 
       BACKGROUND 
       [0002]    A clutch is a mechanical device that engages and disengages the power transmission, especially from driving shaft to driven shaft. Clutches are used whenever the transmission of power or motion must be controlled either in amount or over time (e.g., clutches control whether automobiles transmit engine power to the wheels). Typically, a friction clutch consists of at least a flywheel, which is connected to the engine through an input shaft, a clutch disc, which is connected to the gearbox (e.g., transmission) through an output shaft, a pressure plate, and an actuator. To engage the clutch, the actuator provides pressure to the pressure plate to force the friction surface of the clutch disc tightly against the friction surface of the rotating flywheel. The contact between the friction surfaces causes the clutch disc to rotate and provide power to the gearbox. To disengage, the pressure is removed from pressure plate, which in turn releases the clutch disc from contact with the flywheel. The main components of a clutch disc are the wedge plate and a splined hub, but are often fitted with dampers. 
         [0003]    Electrodynamics is the creation of a magnetic field from an electric current. When electricity passed through a wire, a magnetic field is created around the wire. Looping the wire increases the magnetic field. Adding an iron core greatly increases the magnetic effect and creates an electromagnet. 
         [0004]    Wedge-based clutches are advantageous because they feature a self-reinforcement function and produce a large normal force from a small actuation force. As a result, a wedge clutch can be space-saving and energy-saving. Wedge clutches that use a tapered (conic) surface between the hub and wedge plate can be problematic. Under torque, the tapered surface has the tendency to cause the hub, which has been displaced axially into engagement to lock the wedge clutch, to be forced back out of engagement due to the reaction forces as a result of the angled surface. Eliminating the need for this tapered surface would remove this issue. Eliminating the tapered surface would also reduce the axial displacement needed to actuate the wedge clutch and the energy needed for the axial displacement, which would allow an electromagnet powered by a low voltage battery to actuate the clutch. 
         [0005]    It therefore is an object of the disclosure to provide a wedge clutch disc assembly having detents, where the wedge clutch disc assembly can be actuated using an electromagnet. 
       SUMMARY 
       [0006]    According to aspects illustrated herein, there is provided a wedge clutch assembly for transferring torque from an engine to an output shaft, comprising a clutch carrier operatively arranged to receive torque from the engine, the clutch carrier comprising a first axial friction surface and a first radially inwardly facing surface, a hub operatively arranged to non-rotatably lock with the output shaft, the hub comprising a first radially outwardly facing surface having one or more grooves positioned circumferentially thereon and one or more detents positioned within the one or more grooves, the first radially outwardly facing surface comprising a first plurality of arc surfaces, a wedge plate comprising at least one axial friction surface, a second radially outwardly facing surface, and a second radially inwardly facing surface having one or more recesses and a second plurality of arc surfaces, the one or more recesses operatively arranged to align with the one or more detents, a pressure plate concentrically arranged within the first radially inwardly facing surface and displaceable such that in an engaged mode, an axial force is applied to the pressure plate, in a first axial direction, to engage the wedge plate with the clutch carrier such that torque is transferred from the engine to the output shaft, and in a disengaged mode, the wedge plate is independently rotatable from the clutch carrier. 
         [0007]    According to aspects illustrated herein, there is provided an electromagnetic actuator, the actuator comprises an electromagnet, comprising a core and a coil concentrically arranged within the core, an armature, a support tube, comprising a first end having an axial surface, the axial surface having a concentric groove, and a second end having a neck, a thrust bearing operatively arranged within the groove to engage the pressure plate, an actuator spring concentrically arranged around the neck, a spring tube, comprising a first end concentrically arranged around the actuator spring, and a second end fixedly secured to the armature, in the disengaged mode, an axially disposed space separates the armature from the core, and in the engaged mode, the armature is displaced in the first axial direction to abut against the core. 
         [0008]    These and other objects, features, and advantages of the present invention will become readily apparent upon a review of the following detailed description of the invention, in view of the drawings and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which: 
           [0010]      FIG. 1  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
           [0011]      FIG. 2  is a fragmentary cross-sectional side view of a wedge clutch assembly with detents and an electromagnetic actuator inside a housing; 
           [0012]      FIG. 3  is a fragmentary cross-sectional side view of the wedge clutch assembly with detents and electromagnetic actuator in  FIG. 2 ; 
           [0013]      FIG. 4A  is a cross-sectional side view of a wedge clutch assembly and an electromagnetic actuation component; 
           [0014]      FIG. 4B  is a cross-sectional view of the wedge clutch assembly, in disengaged mode, taken along line  4 B- 4 B in  FIG. 4A ; 
           [0015]      FIG. 5  is an exploded perspective view of the wedge clutch assembly with detents and electromagnetic actuator shown in  FIG. 4A ; 
           [0016]      FIG. 6A  is a cross-sectional view of a wedge clutch assembly with detents in a disengaged mode; 
           [0017]      FIG. 6B  is an enlarged view of the detail shown in  FIG. 6A ; 
           [0018]      FIG. 7A  is a cross-sectional view of a wedge clutch assembly with detents in an engaged position; and, 
           [0019]      FIG. 7B  is an enlarged view of the detail shown in  FIG. 7A . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. It is to be understood that the invention as claimed is not limited to the disclosed aspects. 
         [0021]    Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention. 
         [0022]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention pertains. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention. The assembly of the present invention could be driven by hydraulics, electronics, and/or pneumatics. 
         [0023]    It should be appreciated that the term “substantially” is synonymous with terms such as “nearly,” “very nearly,” “about,” “approximately,” “around,” “bordering on,” “close to,” “essentially,” “in the neighborhood of” “in the vicinity of” etc., and such terms may be used interchangeably as appearing in the specification and claims. It should be appreciated that the term “proximate” is synonymous with terms such as “nearby,” “close,” “adjacent,” “neighboring,” “immediate,” “adjoining,” etc., and such terms may be used interchangeably as appearing in the specification and claims. The term “approximately” is intended to mean values within ten percent of the specified value. 
         [0024]    By “non-rotatably connected” elements, we mean that: the elements are connected so that whenever one of the elements rotate, all the elements rotate; and relative rotation between the elements is not possible. Radial and/or axial movement of non-rotatably connected elements with respect to each other is possible, but not required. 
         [0025]    Adverting now to the figures,  FIG. 1  is a perspective view of cylindrical coordinate system  10  demonstrating spatial terminology used in the present application. The present application is at least partially described within the context of a cylindrical coordinate system. System  10  includes longitudinal axis  11 , used as the reference for the directional and spatial terms that follow. Axial direction AD is parallel to axis  11 . Radial direction RD is orthogonal to axis  11 . Circumferential direction CD is defined by an endpoint of radius R (orthogonal to axis  11 ) rotated about axis  11 . 
         [0026]    To clarify the spatial terminology, objects  12 ,  13 , and  14  are used. An axial surface, such as surface  15  of object  22 , is formed by a plane co-planar with axis  11 . Axis  11  passes through planar surface  15 ; however any planar surface co-planar with axis  11  is an axial surface. A radial surface, such as surface  16  of object  13 , is formed by a plane orthogonal to axis  11  and co-planar with a radius, for example, radius  17 . Radius  17  passes through planar surface  16 ; however any planar surface co-planar with radius  17  is a radial surface. Surface  18  of object  14  forms a circumferential, or cylindrical, surface. For example, circumference  19  passes through surface  18 . As a further example, axial movement is parallel to axis  11 , radial movement is orthogonal to axis  11 , and circumferential movement is parallel to circumference  19 . Rotational movement is with respect to axis  11 . The adverbs “axially,” “radially,” and “circumferentially” refer to orientations parallel to axis  11 , radius  17 , and circumference  19 , respectively. For example, an axially disposed surface or edge extends in direction AD, a radially disposed surface or edge extends in direction R, and a circumferentially disposed surface or edge extends in direction CD. 
         [0027]      FIG. 2  is a fragmentary cross-sectional side view of wedge clutch assembly  20  with detents  30  and electromagnetic actuator  40  inside a housing.  FIG. 2  shows input shaft  80  and output shaft  90  supported by shaft support bearings  82  and  92 , respectively. Electromagnetic actuator  40  provides the axial actuation force to engage wedge clutch assembly  20 . It should be appreciated, however, that any other suitable means of actuation may be used. For example, the axial actuation force may be applied using hydraulic, pneumatic, mechanical (i.e., pedals or levers), or electrical (electrically actuated components) actuation methods. 
         [0028]    Wedge clutch assembly  20  comprises clutch carrier  22 , hub  24 , one or more detents  30 , wedge plate  26 , and pressure plate  28 . Clutch carrier  22  is a circular tube comprising axial friction surface  60 , inward facing radial friction surface  70 , and an internal spline surface. Radial friction surface  70  comprises one or more channels arranged axially thereon (see  FIG. 4B ). 
         [0029]    Hub  24  is a circular tube comprising radially outward facing surface  25  having detent slots  36  arranged radially thereon, and hub ramps  24 A. Hub ramps  24 A are one or more arc surfaces operatively arranged on hub  24  radially outward facing surface  25  to lock hub  24  and wedge plate  26 . Hub  24  includes an internal spline surface. Output shaft  90  is splined to hub  24  internal spline surface. 
         [0030]    Detents  30  comprise detent springs  32  and detent pins  34 . Detents  30  are arranged in detent slots  36  such that detent springs  32  force detent pins  34  to protrude from hub  24  radially outward facing surface  25 . Detent springs  32  are any compressive springs capable of maintaining a sufficient radial force between hub  24  and detent pins  34 . For example: in the disengaged mode, detent springs  32  provide enough radial outward force to detent pins  34  to engage recesses  38  and prevent wedge plate  26  from rotating relative to hub  24 ; and in the engaged mode, detent springs  32  sufficiently compress to allow detent pins  34  to fully depress within detent slots  36 . Detent pins  34  are rollers, keys, or pins capable of: in the disengaged mode, engaging recesses  38 ; and in the engaged mode, being fully depressed within detent slots  36  by wedge plate  26 . Optional washers  100  are annular plates operatively arranged to prevent detents  30  from displacing axially in detent slots  38 . 
         [0031]    Wedge plate  26  is an annular plate comprising axial friction surface  62  and outward facing radial friction surface  72 . Wedge plate  26  comprises a radially inward facing surface having recesses  38  and wedge plate ramps  26 A. Recesses  38  are radially arranged to align with detents  30  such that, during disengaged mode, detent pins  34  engage therein. Wedge plate ramps  26 A are one or more arc surfaces operatively arranged on wedge plate  26  radially inward facing surface to lock wedge plate  26  and hub  24 . Wedge plate  26  comprises a radially disposed space (i.e., discontinuous in a circumferential direction), to allow wedge plate  26  to expand radially outward such that radial friction surface  72  engages radial friction surface  70 . Wedge plate  26  is concentrically arranged within clutch carrier  22 . Hub  24  with detents  30  arranged in detent slots  36  is concentrically arranged within wedge plate  26 . 
         [0032]    Pressure plate  28  is a circular plate concentrically arranged within clutch carrier  22 . Pressure plate  28  comprises one or more tabs, which engage clutch carrier  22  one or more channels such that pressure plate  28  and clutch carrier  22  are non-rotatably locked. Pressure plate  28  is operatively arranged to displace axially within clutch carrier  22 . 
         [0033]    Electromagnetic actuator  40  comprises core  42 , coil  44 , spring tube  46 , support tube  48 , armature  50 , actuator spring  52 , and thrust bearing  54 . Core  42  is an annular ring comprising magnetic contact surface  64  having a concentric groove. In an example embodiment, magnetic contact surface  64  further comprises a plurality of return springs  56  operatively arranged to engage armature  50 . Return springs  56  return armature  50  in direction AD 1  and remove the axial load from pressure plate  28  after the electromagnet is powered down. Coil  44  is concentrically arranged within core  42  concentric groove. Coil  44  is a metal wire capable of conducting electricity and creating a magnetic field such as, for example, copper. Core  42  is a material capable of strengthening the magnetic field created by coil  44  such as, for example, iron. A power supply provides an electric current through coil  44  such that core  42  and coil  44  create an electromagnet, which produces a magnetic field capable of magnetizing armature  50 . It should be appreciated, however, that any other suitable means for magnetizing armature  50  may be used. 
         [0034]    Armature  50  is an annular plate capable of being magnetized by the electromagnet (i.e., core  42 , coil  44 , and electric current). Armature  50  and core  42  are arranged concentrically such that: in a disengaged mode, an axially disposed space separates armature  50  from core  42 ; and in an engaged mode, armature  50  is displaced in axial direction AD 2  and abuts against core  42  at magnetic contact surface  64 . 
         [0035]    Support tube  48  is a circular tube comprising an axial surface end having a concentric groove, and a second end having a neck. Support tube  48  neck comprises an external flange and is operatively arranged to axially engage actuator spring  52 . 
         [0036]    Thrust bearing  54  is an annular bearing operatively arranged within support tube  48  concentric groove to engage pressure plate  28 . Thrust bearing  54  is any type of rotary rolling-element bearing that permits rotation between support tube  48  and pressure plate  28  and supports a predominately axial load between electromagnetic actuator  40  and wedge clutch assembly  20 . 
         [0037]    Actuator spring  52  is a compression coil spring concentrically arranged around support tube  48  neck. Actuator spring  52  can be any compression coil spring capable of storing energy and, after subsequently releasing it, returning to its natural length. Actuator spring  52  softens the response of the clutch engagement (i.e., pressure plate  28  presses wedge plate  26  tightly against clutch carrier  22 ) and disengagement (i.e., pressure is removed releasing wedge plate  26  from contact with clutch carrier  22 ), and maintains a force, and thus contact, between support tube  48  and spring tube  46 . 
         [0038]    Spring tube  46  is a circular tube comprising an internal flange. Spring tube  46  is concentrically arranged inside core  42  and is fixedly secured to armature  50 . Spring tube  46  is concentrically arranged around actuator spring  52  such that spring tube  46  internal flange axially engages actuator spring  52 . 
         [0039]      FIG. 3  is a fragmentary cross-sectional side view of wedge clutch assembly  20  with detents  30  and electromagnetic actuator  40  shown in  FIG. 2 . Detents  30  comprise detent springs  32  and detent pins  34 . It should be appreciated, however, that any other suitable design for detents  30  may be used. Torque enters input shaft  80 , which is splined to clutch carrier  22 . When electromagnetic actuator  40  is energized, the magnetic field displaces armature  50  (and also spring tube  46 ) in direction AD 2  to abut against core  42  at magnetic contact surface  62 , which compresses actuator spring  52  in spring tube  46 . Actuator spring  52  reacts against support tube  48 , which applies an axial load through thrust bearing  54 , into pressure plate  28 . Pressure plate  48  and clutch carrier  22  are non-rotatably locked (pressure plate  28  tabs are engaged in clutch carrier  22  channels). The axial load causes pressure plate  28  to press wedge plate axial friction surface  62  against clutch carrier axial friction surface  60 , thus creating frictional drag between wedge plate  26  and clutch carrier  22 . Frictional engagement occurs when the frictional drag is large enough to circumferentially shift wedge plate  26  to overcome detent springs  32  and depress detent pins  34  into detent slots  36 . Hub ramps  24 A lock with wedge plate ramps  26 A and torque is transferred from input shaft  80  to output shaft  90  (described further with respect to  FIGS. 6 and 7  below). 
         [0040]      FIG. 4A  is a cross-sectional side view of wedge clutch assembly  20  and electromagnetic actuator  40  as separate components.  FIG. 4B  is a cross-sectional view of wedge clutch assembly  20 , in disengaged mode, taken along line  4 B- 4 B in  FIG. 4A . Wedge clutch assembly  20  comprises single wedge plate  26  including a straight, un-tapered, inner profile surface, clutch carrier  22 , hub  24  having a straight, un-tapered, outer profile surface to closely conform to wedge plate  26  inner profile surface, and detent slots  36  for detents  30 . Detents  30  comprise springs  32  and detent pins  34 . Detent pins  34  are rollers, keys, or pins. Detent pins  34  are forced radially outward by detent springs  32  such that they protrude from the effective outer diameter of hub  24  to engage recesses  38 . Detent pins  34  prevent wedge plate  26  from rotating relative to hub  24  until sufficient tangential force is applied to detent pins  34  to compress detent springs  32 . In disengaged mode, wedge plate  26  and clutch carrier  22  are not frictionally engaged. It should be appreciated that, in disengaged mode, contact between axial friction surfaces  62  and  60  can occur and create frictional drag between wedge plate  26  and clutch carrier  22 . Frictional drag is a circumferential force. However, any contact between axial friction surfaces  62  and  60  in disengaged mode will not create enough frictional drag between wedge plate  26  and clutch carrier  22  to generate frictional engagement. Further, no contact occurs, and thus no frictional drag is created, between wedge plate outward facing radial friction surface  72  and clutch carrier inward facing radial friction surface. 
         [0041]      FIG. 5  is an exploded perspective view of wedge clutch assembly  20  with detents  30  and electromagnetic actuator  40  shown in  FIG. 4A . Wedge clutch assembly  20  comprises clutch carrier  22 , wedge plate  26 , pressure plate  28 , hub  24 , detents  30 , and optional washers  100 . Detents  30  comprise detent springs  32  and detent pins  34  assembled within detent slots  36 . Wedge plate  26 , pressure plate  28 , hub  24 , and optional washers  100  are assembled concentrically within clutch carrier  22 . Electromagnetic actuator  40  comprises thrust bearing  54 , support tube  48 , actuator spring  52 , spring tube  46 , core  42 , coil  44 , and armature  50 . In an example embodiment, core  42  includes return springs  56  arranged on magnetic contact surface  60  to return armature  50  in direction AD 1  and remove the axial load on pressure plate  28 . It should be appreciated that when wedge clutch assembly  20  and electromagnetic actuator  40  are fully assembled, clutch carrier  22 , wedge plate  26 , pressure plate  28 , hub  24 , optional washers  100 , thrust bearing  54 , support tube  48 , actuator spring  52 , spring tube  46 , core  42 , coil  44 , and armature  50  are concentrically arranged about an axis of rotation (see  FIG. 3 ). 
         [0042]      FIG. 6A  is a cross-sectional view of wedge clutch assembly  20  with detents  30  in a disengaged (or neutral) position. Wedge clutch assembly  20  is disengaged when no power is provided to electromagnetic actuator  40  and no axial load is applied to pressure plate  28 .  FIG. 6B  is an enlarged view of the detail shown in  FIG. 6A .  FIG. 6B  shows detent springs  32  providing radial outward force to detent pins  34  such that they protrude from the effective outer diameter of hub  24  and engage recesses  38 . Detents  30  prevent wedge plate ramps  26 A from riding hub ramps  24 A until enough frictional drag is created to circumferentially displace wedge plate  26 . 
         [0043]      FIG. 7A  is a cross-sectional view of wedge clutch assembly  20  with detents  30  in an engaged (or locked) position. When power is supplied to electromagnetic actuator  40 , armature  50  is displaced to abut against magnetic contact surface  64  causing pressure plate  28  to squeeze wedge plate  26  against clutch carrier  22 .  FIG. 7B  is an enlarged view of the detail shown in  FIG. 7A .  FIG. 7B  shows detent pins  34  depressed within detent slots  36 . Wedge plate  26  is displaced in circumferential direction CD 2  such that wedge ramps  26 A are riding hub ramps  24 A. Hub ramps  24 A interfere with wedge ramps  26 A such that, when enough frictional drag is created between axial friction surfaces  62  and  60  cause wedge plate  26 , wedge plate  26  expands radially outward such that wedge plate outward facing radial friction surface  72  engages clutch carrier inward facing radial friction surface  70 . When the power supply is terminated, return springs  56  return armature  50  to its initial position such that the axial load is removed, wedge plate  26  shifts circumferentially in direction CD 1 , wedge plate ramps  26 A unlock from hub ramps  24 A, wedge plate  26  contracts, disengaging wedge plate outward facing radial friction surface  72  from clutch carrier inward facing radial friction surface  70 , and detent springs  32  force detent pins  34  into recesses  38 . 
         [0044]    It will be appreciated that various aspects of the above-disclosed invention and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           10  Cylindrical Coordinate System 
           11  Longitudinal Axis 
           12  Object 
           13  Object 
           14  Object 
           15  Axial Surface 
           16  Radial Surface 
           17  Radius 
           18  Surface 
           19  Circumference 
           20  Wedge Clutch Assembly 
           22  Clutch Carrier 
           24  Hub 
           24 A Hub Ramps 
           25  Hub Radially Outward Facing Surface 
           26  Wedge Plate 
           26 A Wedge Plate Ramps 
           28  Pressure Plate 
           30  Detents 
           32  Detent Springs 
           34  Detent Pins 
           36  Detent Slots 
           38  Recesses 
           40  Electromagnetic Actuator 
           42  Core 
           44  Coil 
           46  Spring Tube 
           48  Support Tube 
           50  Armature 
           52  Actuator Spring 
           54  Thrust Bearing 
           56  Return Springs 
           60  Clutch Carrier Axial Friction Surface 
           62  Wedge Plate Axial Friction Surface 
           64  Magnetic Contact Surface 
           70  Clutch Carrier Inward Facing Radial Friction Surface 
           72  Wedge Plate Outward Facing Radial Friction Surface 
           80  Input Shaft 
           82  Input Shaft Support Bearing 
           90  Output Shaft 
           92  Output Shaft Support Bearing 
           100  Optional Washers 
         AD 1  Axial Direction  1   
         AD 2  Axial Direction  2