Abstract:
A self-retained constant velocity joint has a ring-shaped cage disposed substantially concentrically to and spaced radially from a race of the joint. A plurality of grooves in and distributed circumferentially about the race preferably includes longitudinal, clockwise and counter-clockwise grooves that extend substantially axially and communicate radially through the arcuate surface. A ball is located in each groove and extends through respective windows in the cage. Preferably, the windows associated with the clockwise and counter-clockwise grooves extend circumferentially further than the windows associated with the longitudinal grooves. The cage carries an arcuate face that is one of a convex and concave profile and radially opposes the arcuate surface that is the other of the convex and concave profiles. The radial distance between the face and surface is such that axial movement between the race and cage is limited by intermittent contact of the face with the surface.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a stroking ball-type constant velocity joint, and more specifically to a self-retained constant velocity joint kinematically defined by longitudinal grooves and helical grooves for guiding movement of balls. 
       BACKGROUND OF THE INVENTION 
       [0002]    A stroking ball-type constant velocity joint facilitates rotational movement between a driving shaft and a driven shaft. The stroking ball-type joint is especially useful in applications wherein the driving and driven shafts are angled with respect to one another. The stroking ball-type joint includes an inner race attached to one of the shafts and an outer race attached to the other shaft. The inner and outer races define grooves or channels which cooperate to form passages. Roller balls are positioned in the passages and torque is transmitted between the shafts with the roller balls. 
         [0003]    Stroking ball-type joints can include six-balls or eight-balls. Generally, six-ball stroking ball-type joints provide greater stroke and angle capabilities than eight-ball joints. On the other hand, eight-ball joints generally can be more compact than six-ball joints. It is desirable to develop a stroking ball-type joint having the advantage of compactness provided by eight-ball joints with the stroke and angle capabilities of six-ball joints, while at the same time improving NVH (Noise Vibration and Harshness) characteristics and mechanical efficiency. Yet further, it would be desirable to develop self-retained joints wherein at least a portion of the joint has the ability to hold itself together prior to full assembly in any environmental application. 
       SUMMARY OF THE INVENTION 
       [0004]    A self-retained constant velocity joint has a ring-shaped cage disposed substantially concentrically to and spaced radially from a race of the joint. A plurality of grooves in and distributed circumferentially about the race preferably includes longitudinal, clockwise and counter-clockwise grooves that extend substantially axially and communicate radially through the arcuate surface. A ball is located in each groove and extends through respective windows in the cage. Preferably, the windows associated with the clockwise and counter-clockwise grooves extend circumferentially further than the windows associated with the longitudinal grooves. The cage carries an arcuate face that is one of a convex and concave profile and radially opposes the arcuate surface that is the other of the convex and concave profiles. The radial distance between the face and surface is such that axial movement between the race and cage is limited by intermittent contact of the face with the surface. 
         [0005]    Preferably, the race that is self-retained to the cage is an inner race with the surface being an outer surface having a convex profile. The grooves cooperate with corresponding channels in an outer race such that the helical channels of the outer race cooperate with the helical grooves of the inner race to form cross groove passages. That is, clockwise grooves are associated with counter-clockwise channels and vice-versa. 
         [0006]    The ring-shaped cage is located radially between the inner and outer races and is spaced radially outward preferably from the inner race allowing for telescopic movement of the joint. Because the outer surface of the inner race preferably has the convex profile and the opposing inner face of the cage has the concave profile, the outer surface has a maximum diameter that is greater than a minimum diameter of the inner surface. This relationship of diameters retains the cage to the inner race. 
         [0007]    Objects, features and advantages of the present invention include a ball-type constant velocity joint that is compact in design while having large angles of magnitude, has telescoping capability and is self retained. Other advantages include a robust, light weight, design requiring little or no maintenance and in service has a long and useful life. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0009]      FIG. 1  is an exploded perspective view of a self-retained constant velocity joint embodying the present invention; 
           [0010]      FIG. 2  is a perspective view of the self-retained constant velocity joint with an outer race segmented to show internal detail; 
           [0011]      FIG. 3  is a front view of the self-retained constant velocity joint; 
           [0012]      FIG. 4  is a cross section of the self-retained constant velocity joint taken along line  4 - 4  of  FIG. 3  and illustrated in an axial co-extending state and telescopically retracted position; 
           [0013]      FIG. 5  is a cross section of the self-retained constant velocity joint similar in perspective to  FIG. 4  except illustrated in a telescopically extended position; 
           [0014]      FIG. 6  is a cross section of the self-retained constant velocity joint similar in perspective to  FIG. 5  except illustrated in an angled state while generally in the telescopically extended position; 
           [0015]      FIG. 7  is a front view of an inner race of the self-retained constant velocity joint; 
           [0016]      FIG. 8  is a plan view of an outer surface of the inner race viewed along line  8 - 8  of  FIG. 7 ; 
           [0017]      FIG. 9  is a front view of the outer race; 
           [0018]      FIG. 10  is a plan view of an inner surface of the outer race viewed along line  10 - 10  of  FIG. 9 ; 
           [0019]      FIG. 11  is a cross section of a cage of the self-retained constant velocity joint taken along an imaginary plane co-extending with a rotation axis of the cage; 
           [0020]      FIG. 12  is a partial side view of the cage illustrating a long window; and 
           [0021]      FIG. 13  is a partial side view of the cage illustrating a short window. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    As illustrated in  FIGS. 1-3  and  6 , the present invention is a self-retained constant velocity joint  20  preferably of a stroking ball-type. The joint  20  has an inner race  22  connected rigidly and disposed concentrically to an end of a first shaft (not shown) that rotates about a first axis  24 . The inner race  22  is generally surrounded circumferentially by a cage  26  that rotates about a second axis  27 , and the cage  26  is surrounded circumferentially by an outer race  28 . The outer race  28  is connected rigidly to a second shaft (not shown) that rotates about a third axis  30 . Preferably, eight balls  29  are located radially between the inner and outer races  22 ,  28  and spaced circumferentially from one another with respect to axes  24 ,  30 . 
         [0023]    For the sake of explanation and with respect to the figures, a forward direction is illustrated by arrow  32  and a rearward direction is illustrated by arrow  34  (as best shown in  FIG. 1 ). Referring to  FIGS. 1 ,  4 ,  6  and  7 , the inner race  22  preferably has an annular forward wall  36  and an opposite annular rearward wall  38  each having a generally circular and radially outward perimeter  40  having a diameter  42 . 
         [0024]    A circumferentially extending outward surface  44  of the inner race  22  spans contiguously from and axially (with respect to axis  24 ) between the outward perimeters  40  of the forward and rearward walls  36 ,  38 . The outward surface  44  has a forward portion  46 , an apex portion  48  and a rearward portion  50  that all extend circumferentially with respect to axis  24 , and with the apex portion  48  being located axially directly between the forward and rearward portions  46 ,  50 . The forward portion  46  spans axially and contiguously rearward from the forward perimeter  40 , and diverges radially outward to the apex portion  48 . The generally cylindrical apex portion  48  thus has a diameter  52  that is greater than the diameter  42  of the forward and rearward perimeters  40  (as best shown in  FIG. 4 ). Similarly, the rearward portion  50  spans axially and contiguously forward from the rearward perimeter  40  of the rearward wall  38 , and diverges radially outward to the apex portion  48 . Generally, a cross section of inner race  22  taken through an imaginary plane co-extending with axis  24  illustrates a convex profile of the outward surface  44 . Thus, the diameter  42  of the perimeter  40  may be considered as the minimum diameter of the outward surface  44  and the diameter  52  of the apex portion  48  may be the maximum diameter of the surface  44 . 
         [0025]    Referring to  FIGS. 7 and 8 , the inner race  22  preferably has eight or a series of grooves  54  that longitudinally extend axially with respect to axis  24  and communicate radially outward through the outward surface  44 . For compact construction of the joint  20 , each one of the series of grooves  54  also communicate through the forward and rearward perimeters  40 , thus generally making the perimeters circumferentially discontinuous. Each groove of the series of grooves  54  is spaced circumferentially from the next adjacent one of the series of grooves  54 . Preferably, the series of grooves  54  have four longitudinal grooves  56  that extend parallel to axis  24 , two helical clockwise grooves  58  that slightly spiral or angle in a clockwise direction as the grooves  58  longitudinally extend axially rearward (i.e. rearward direction/arrow  34 ), and two helical counter-clockwise grooves  60  that slightly spiral, or angle in a counter-clockwise direction as the grooves  60  longitudinally extend axially rearward. The spiraling affect of the grooves  58 ,  60  may not be truly helical in shape, and instead may be simply angled with respect to the longitudinal grooves  56  and as best illustrated in  FIG. 8 . 
         [0026]    Each longitudinal groove  56  is circumferentially adjacent to a clockwise groove  58  on one side and a counter-clockwise groove  60  on the opposite side. Moreover, each helical or angled groove  58 ,  60  is located circumferentially between two longitudinal grooves  56  of the series of grooves  54 . The longitudinal grooves  56  are preferably spaced angularly by about ninety degrees from one another. As best illustrated in  FIG. 8 , each angled groove  58 ,  60  is inclined with respect to the adjacent longitudinal grooves  56  by respective positive and negative angles represented by arrows  62 ,  64 . The absolute magnitude of the angles or arrows  62 ,  64  are about or preferably are equal to one another. 
         [0027]    Referring to FIGS.  1  and  9 - 10 , the outer race  28  has an annular forward wall  66  and an opposite annular rearward wall  68 , both disposed substantially perpendicular to axis  30 . A circumferentially extending inner surface  70  of the outer race  28  spans laterally in an axial direction (with respect to axis  30 ) between the forward and rearward walls  66 ,  68 . The outer race  28  preferably has eight channels or grooves  72  that longitudinally extend axially with respect to axis  30  and communicate laterally inward (i.e. radially inward with respect to axis  30 ) through the inner surface  70 . Each channel of the series of channels  72  is associated with a respective one of the series of grooves  54 , and is thus spaced circumferentially from the next adjacent one of the series of channels  72 . 
         [0028]    Preferably, the series of channels  72  have four longitudinal channels  74  that extend parallel to axis  30 , two helical clockwise channels  76  that slightly spiral or angle in a clockwise direction as the channels  76  longitudinally extend axially rearward (i.e. rearward direction/arrow  34 ), and two helical counter-clockwise channels  78  that slightly spiral or angle in a counter-clockwise direction as the channels  78  longitudinally extend axially rearward. The spiraling affect of the channels  76 ,  78  may not be truly helical in shape, and instead may be simply angled with respect to the longitudinal grooves  58  and as best illustrated in  FIG. 10 . 
         [0029]    Each longitudinal channel  74  is circumferentially adjacent to a clockwise channel  76  on one side and a counter-clockwise channel  78  on the opposite side. Moreover, each helical or angled channel  76 ,  78  is located circumferentially between two longitudinal channels  74  of the series of channels  72 . The longitudinal channels  74  are preferably spaced angularly by about ninety degrees from one another. As best illustrated in  FIG. 10 , each angled channel  76 ,  78  is inclined with respect to the adjacent longitudinal channels  74  by respective positive and negative angles  80 ,  82 . Preferably, absolute magnitude of the angles  80 ,  82  are equal to one another and equal to the absolute magnitude of angles  62 ,  64 . 
         [0030]    When the joint  20  is assembled, each one of the longitudinal grooves  56  of the inner race  22  is circumferentially aligned to a respective one of the longitudinal channels  74  of the outer race  28 , thereby forming a passage for travel of a respective one of the balls  29 . Similarly, each one of the clockwise grooves  58  is aligned circumferentially to a respective one of the counter-clockwise channels  78 , and each one of the counter-clockwise grooves  60  is aligned circumferentially to a respective one of the clockwise channels  76  all respectively forming passages for travel of respective balls  29 . 
         [0031]    The inclined or cross groove passages create a constant velocity plane when the joint  20  is angled. The degree of incline of clockwise and counter-clockwise grooves can be smaller than that of a standard 6-ball joint design. The straight or longitudinal passages and cross grooved passages cooperate to allow a greater stroke than a joint that has inclined grooves. In addition, reduction of the helix angle of the helical grooves decreases the contact stresses in the grooves/channels and the forces transmitted to the cage  26  disposed between the inner and outer races  22 ,  28 . Cross groove passages are discussed in greater detail in U.S. Pat. No. 6,468,164, which is incorporated herein by reference. 
         [0032]    Referring to  FIGS. 1-6  and  11 - 13 , the cage  26  of the joint  20  preferably has four short windows  86  and four long windows  88 . All of the windows  86 ,  88  are elongated circumferentially with respect to axis  27  and communicate radially through the cage  26 . Each one of the short windows  86  is associated with (i.e. adjacent to) a respective one of the longitudinal grooves  56  and each one of the long windows  88  is associated with a respective one of the helical or angled grooves  58 ,  60  in the inner race  22 . Preferably, the width of the short and long windows  86 ,  88  are about the same, and are slightly greater than the diameter of the balls  29  for minimizing internal friction of the joint  20 . One skilled in the art, however, would now know that if the diameter of the ball  29  is greater than the width of the windows  86 ,  88 , the cage  26  may generally lock or trap the balls  29  to the inner race  22 . This alternative embodiment, however, would preferably have a frictionless or friction reducing interface between the balls  29  and the cage  26  for smooth operation of the joint  20 . 
         [0033]    The short windows  86  are defined by a continuous wall  90  having opposing side segments  92  and flanking or opposing end segments  94 . The side segments  92  are substantially parallel to one another, extend circumferentially with respect to axis  27 , and define the width of the window  86 . The opposing end segments  94  preferably have a radius of curvature equal to about half the width of window  86 . Similarly, the long windows  88  are defined by a continuous wall  96  having opposing side segments  98  and flanking or opposing end segments  100 . The side segments  98  are substantially parallel to one another, extend circumferentially with respect to axis  27 , and define the width of the window  88 . The opposing end segments  100  preferably have a radius of curvature that when doubled is substantially less than the width of window  88 . Preferably, the width of window  88  is about equal to four time the radius of curvature of the end segments  100 . The large radius of curvature of the end segments  94  of continuous wall  90  of short windows  86  provides structural integrity and strength to the cage  26 . 
         [0034]    The cage  26  is generally ring-shaped having a circumferentially extending inner face  102  that faces radially inward and an opposite outer face  104  facing radially outward. The continuous walls  90 ,  96  span laterally between and form contiguously into the inner and outer faces  102 ,  104 . The inner and outer faces  102 ,  104  preferably have respective spherical radiuses  106 ,  108  that both originate from a common center point  110  that lies on the axis  27  (as best shown in  FIG. 11 ). The inner face  102  thus has a concave profile and the outer face  104  has a convex profile when a cross section is taken along an imaginary plane that co-extends with the axis  27 . 
         [0035]    The inner face  102  of the cage  26  spans laterally (i.e. axially with respect to axis  27 ) between forward and rearward rims  112 ,  114  having substantially equal diameters  116  (see  FIGS. 4 and 11 ). To achieve the retaining feature of the joint  20 , the diameter  116  of the rims  112 ,  114  is less than the diameter  52  of the apex portion  48  of the outer surface  44  of the inner race  22 . To enable the telescoping movement generally along axes  24 ,  27 ,  30  the minimum diameter  42  of the inner race  22  is substantially less than the rim diameter  116  of the cage  26 . 
         [0036]    Referring to  FIGS. 4-6  and during operation, the joint  20  can assume various states and positions. For instance,  FIG. 4  illustrates the joint  20  in an axial co-extending or linear state  118  and a telescopically retracted position  120 .  FIG. 5  illustrates the joint  20  in a telescopically extended position  122 , and  FIG. 6  illustrates the joint  20  in both the telescopically extended position  122  and in an angled state  124 . When the joint  20  is in the linear state  118  all three axes  24 ,  27 ,  30  co-extend to one-another, and thus do not intersect. When the joint  20  is in both the linear state  118  and the retracted position  120 , the inner race  22 , the cage  26  and the outer race  28  are concentric to one-another and thus centralized to the center point  110  of the cage  26 . 
         [0037]    As best shown in  FIGS. 4 and 5  and when the joint is in the retracted position  120  and linear state  118 , the outer surface  44  of the inner race  22  and the inner face  102  of the cage  26  radially define a circumferentially continuous cavity  125  having an annular forward opening  126  and an annular rearward opening  128 . The radial thickness of the cavity  125  is substantially equal to the difference between the spherical radius  106  of the cage  26  and generally half the diameter  52  of the appex portion  48  of the outer surface  44  of the inner race  22 . More specifically, the forward and rearward portions  46 ,  50  of outward surface  44  are generally spherical each having a spherical radius  130  that are axially offset from center point  110  by a distance  132 . Distance  132  is substantially equal to the axial span of substantially cylindrical appex portion  48  and/or half the axial telescoping distance of the joint  20 . Preferably, the spherical radius  106  of the cage  26  is about equal to spherical radius  130  and the offset contributes toward creation or radial span of cavity  125 . 
         [0038]    For purposes of illustration and operational explanation of the joint  20 , the cage  26  as illustrated in  FIGS. 4-6  will be held stationary (i.e. stationary point of reference with axis  27  being horizontal) and the races  22 ,  28  will move relative to the cage  26 . When the joint  20  moves from the retracted position  120  to the extended position  122 , the outer race  28  moves in the rearward direction  34  by the same distance  132  that the inner race  22  moves in the forward direction  32  (and in reference to an imaginary plane  133  disposed perpendicular to axis  27  and crossing through center point  110  of the cage  26 ). When fully in the telescoped or extended position  122 , the forward opening  126  of the cavity  125  is substantially closed because the forward portion  46  of the outer surface  44  is generally in contact with the forward rim  112  of the cage  26 . Because of the symmetry of the joint  20 , this telescoping motion may also be reversed with the inner race moving rearward with respect to plane  133  and with the outer race  28  moving forward by a substantially equal distance. 
         [0039]    As best illustrated in  FIG. 6 , the joint  20  can be both angled and telescoped at the same time. When in the angled state  124  (and regardless of whether the joint  20  is telescoped), the axis  27  of the inner race  22  and the axis  30  of the outer race  28  will intersect axis  27  of the cage  26  at the center point  110  of the cage. Moreover and when angled, the axis  24  of the inner race  22  is angled with respect to axis  27  of the cage  26  by a negative angular displacement represented by arrow  134  and the axis  30  of the outer race  28  is angled with respect to axis  27  by a positive angular displacement represented by arrow  136 . The absolute magnitude of angular displacements  134 ,  136  are about or preferably equal to one another. When the joint  20  is partially or fully telescoped, the intersection of all three axes  24 ,  27 ,  30  is preferably not the center points of the inner and outer races  22 ,  28 , but only of the cage  26 . 
         [0040]    While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. For instance, the outer race  28  may be self-retained to the cage  26  instead of the inner race  22  and in a similar manner. It is not intended herein to mention all the possible equivalent forms or ramification of the invention. It is understood that 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.