Abstract:
A constant velocity universal joint has an outer race provided with longitudinally extending, circumferentially spaced outer race grooves in its inner concave surface. An inner race is provided with longitudinally extending, circumferentially spaced inner race grooves in its outer convex surface. The inner race is disposed within the outer race with its outer convex surface spherically engaged with the inner concave surface of the outer race for relative angular movement of the inner and outer races. Each of the inner race grooves is arranged opposite a corresponding one of the outer race grooves to define a plurality of ball-groove pairs. The grooves of each ball-groove pair are disposed in transverse crossing-relation to one another. A ball is disposed in each of the crossing ball-groove pairs for movement therealong during the relative angular movement of the inner and outer races.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Typically, a constant velocity universal joint has inner and outer spherical races coupled together by a series of balls engaging generally parallel grooves in the races. It is important that the speed of rotation of the two races remains always the same, whatever the angular adjustment of the axes of the two races. This depends on maintaining the plane of the balls so as to bisect the angle of adjustment. At present, this is accomplished by placing a spherical cage between the races, slotted to hold the balls. However, the provision of a cage increases cost, adds an additional part, and generates excess heat in operation.  
         SUMMARY OF THE INVENTION  
         [0002]    The constant velocity universal joint of the present invention dispenses with the cage. The two races spherically engage one another. Each ball is confined by a pair of grooves consisting of a groove in the outer race and a groove in the inner race, with the grooves of each pair in crossing relation to one another so that the ball is properly located. However, a ball can drop out when torque is applied to one of the races and one groove tends to rotate relative to the other. To overcome this problem, and in accordance with one embodiment of this invention, all outer race grooves are circumferentially inclined in one direction, all inner race grooves are circumferentially inclined in the opposite direction, alternate outer race groove centers are offset to one side of the spherical center, the remaining outer race groove centers are offset to the opposite side of the spherical center, and the inner race groove center of each groove pair is offset from the spherical center to the side opposite the side to which the center of the paired outer race groove is offset.  
           [0003]    In accordance with a second embodiment of the invention, alternate outer race grooves are circumferentially inclined in one direction and the remaining outer race grooves are circumferentially inclined in the opposite direction. Each inner race groove is inclined oppositely to the outer race groove with which it is paired. All outer race groove centers are offset to the same side of the spherical center and all inner race groove centers are offset to the same (but opposite) side of the spherical center. The inner race groove center of each groove pair is offset from the spherical center to a side opposite the side to which the center of the paired outer race groove is offset.  
           [0004]    An object of the invention is to provide a constant velocity universal joint having the foregoing features and capabilities. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    Other objects, features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.  
         [0006]    [0006]FIG. 1 is an end view of a universal joint constructed in accordance with this invention;  
         [0007]    [0007]FIG. 2 is a sectional view taken on the line  2 - 2  in FIG. 1;  
         [0008]    [0008]FIG. 3 is a sectional view taken on the line  3 - 3  in FIG. 2;  
         [0009]    [0009]FIG. 4 is a sectional view of the outer race in FIG. 2;  
         [0010]    [0010]FIG. 5 is a side elevational view of the inner race;  
         [0011]    [0011]FIG. 6 is a fragmentary sectional view taken on the line  6 - 6  in FIG. 1;  
         [0012]    [0012]FIG. 7 is a fragmentary sectional view taken on the line  7 - 7  in FIG. 1;  
         [0013]    [0013]FIG. 8 is a fragmentary sectional view taken on the line  8 - 8  in FIG. 1;  
         [0014]    [0014]FIG. 9 is a fragmentary sectional view taken on the line  9 - 9  in FIG. 1;  
         [0015]    [0015]FIG. 10 is a development of the outer and inner races, showing the groove pattern thereof;  
         [0016]    [0016]FIG. 11 is a development of the outer and inner races, showing the groove patterns overlain with one another;  
         [0017]    [0017]FIG. 12 is a diagrammatic perspective view showing a ball between one pair of outer and inner race grooves;  
         [0018]    [0018]FIG. 13 is a diagrammatic view looking down on the showing in FIG. 12;  
         [0019]    [0019]FIG. 14 is a diagrammatic perspective view showing a ball between another pair of outer and inner race grooves;  
         [0020]    [0020]FIG. 15 is a diagrammatic view looking down on the showing in FIG. 14;  
         [0021]    [0021]FIG. 16 is an end view of a universal joint of modified construction;  
         [0022]    [0022]FIG. 17 is a sectional view taken on the line  17 - 17  in FIG. 16;  
         [0023]    [0023]FIG. 18 is a sectional view of the outer race shown in FIG. 16, and taken on the line  18 - 18  in FIG. 16;  
         [0024]    [0024]FIG. 19 is a side elevational view of the inner race of the embodiment shown in FIG. 16;  
         [0025]    [0025]FIG. 20 is a development of the outer and inner races of the embodiment of FIG. 16, showing the groove pattern thereof;  
         [0026]    [0026]FIG. 21 is a fragmentary sectional view taken on the line  21 - 21  in FIG. 16;  
         [0027]    [0027]FIG. 22 is a fragmentary sectional view taken on the line  22 - 22  in FIG. 16;  
         [0028]    [0028]FIG. 23 is a development of the outer and inner races, showing the groove patterns in FIG. 20 overlain with one another;  
         [0029]    [0029]FIG. 24 is a diagrammatic perspective view showing a ball between one pair of outer and inner race grooves of the universal joint shown in FIG. 16;  
         [0030]    [0030]FIG. 25 is a diagrammatic view looking down on the showing in FIG. 24;  
         [0031]    [0031]FIG. 26 is a diagrammatic perspective view showing a ball between another pair of outer and inner race grooves of the universal joint shown in FIG. 16; and  
         [0032]    [0032]FIG. 27 is a diagrammatic view looking down on the showing in FIG. 26. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0033]    Referring now more particularly to the drawings and especially FIGS. 1-15, there is shown a constant velocity universal joint  20  having an outer race  22  which is integral with or otherwise secured to a shaft  24 , and an inner race  26  which is integral with or otherwise attached to a shaft  28 . The outer race  22  has an inner, spherical, concave surface  30  disposed about a longitudinal axis  32  of the outer race. The inner race  26  has an outer, spherical, convex surface  34  disposed about a longitudinal axis  36  of the inner race. The inner and outer races  22 ,  26  and their spherical surfaces  30  and  34  have a common center  38 , which is the center of the joint, and the surfaces  30  and  34  are spherically engaged with one another.  
         [0034]    The concave surface  30  of the outer race  20  has a plurality (in this embodiment  8 ) of arcuate, generally longitudinally extending, circumferentially spaced outer race grooves  40  and  42  which are alternated with one another. The convex surface  34  of the inner race  26  has the same number of arcuate, generally longitudinally extending, circumferentially spaced inner race grooves  44  and  46  with are alternated with one another. The grooves  40  and  44  of the two races are paired with one another to provide a plurality of groove pairs  48  (FIG. 12). The grooves  42  and  46  of the two races are paired with one another to provide a plurality of groove pairs  50  (FIG. 14).  
         [0035]    All of the outer race grooves  40  and  42  are inclined circumferentially in one direction and all of the inner race grooves  44  and  46  are inclined circumferentially in the opposite direction so that the grooves  40 ,  44  of each of the groove pairs  48  are in crossing relation to one another, and the grooves  42 ,  46  of each of the groove pairs  50  are in crossing relation to one another. See FIGS. 4, 5,  10  and  11 .  
         [0036]    A torque-transmitting ball  52  is confined by the outer race groove and the inner race groove of each of the groove pairs  48  and  50 .  
         [0037]    The alternate outer race grooves  40  are arcuate and have centers of curvature located at  53  offset to one side of the joint center  38  (FIG. 7). The remaining outer race grooves  42  are arcuate and have centers of curvature located at  54  offset to the opposite side of the joint center  38  (FIG. 9). The alternate inner race grooves  44  have centers of curvature at  54  and the remaining inner race grooves  46  have centers of curvature at  53 . See FIGS. 6 and 8. The centers  53  and  54  are offset the same distance from the joint center  38 .  
         [0038]    Referring now to FIGS. 16-27, there is shown a constant velocity universal joint  120  having an outer race  122  which is splined or otherwise secured to a shaft  124 , and an inner race  126  which is integral with or otherwise attached to a shaft  128 . The outer race  122  has an inner, spherical, concave surface  130  disposed about a longitudinal axis  132  of the outer race. The inner race  126  has an outer, spherical, convex surface  134  disposed about a longitudinal axis  136  of the inner race. The inner and outer races  122 ,  126  and their spherical surfaces  130  and  134  have a common center  138 , which is the center of the joint, and the surfaces  130  and  134  are spherically engaged with one another.  
         [0039]    The concave surface  130  of the outer race  120  has a plurality (again there are eight) of arcuate, generally longitudinally extending, circumferentially spaced outer race grooves  140  and  142  which are alternated with one another. The convex surface  134  of the inner race  126  has the same number of arcuate, generally longitudinally extending, circumferentially spaced inner race grooves  144  and  146  which are alternated with one another. The grooves  140  and  144  of the two races are paired with one another to provide a plurality of groove pairs  148  (FIG. 24). The grooves  142  and  146  of the two races are paired with one another to provide a plurality of groove pairs  150  (FIG. 26).  
         [0040]    Alternate grooves  140  of the outer race  120  are inclined circumferentially in one direction and the remaining grooves  142  are inclined circumferentially in the opposite direction. Alternate grooves  144  of the inner race  126  are circumferentially inclined oppositely to the grooves  140  with which they are paired, and the remaining inner race grooves  146  are circumferentially inclined oppositely to the grooves  142  with which they are paired. Thus the grooves of each pair are inclined oppositely to one another.  
         [0041]    A torque-transmitting ball  152  is confined by the outer race groove and the inner race groove of each of the groove pairs  148  and  150 .  
         [0042]    All of the outer race grooves  140  and  142  are arcuate and have centers of curvature located at  153  offset to one side of the joint center  138 . All of the inner race grooves  144  and  146  are arcuate and have centers of curvature located at  154  offset to the opposite side of the joint center  138 . The centers  153  and  154  are offset the same distance from the joint center  138 . See FIGS. 21 and 22.  
         [0043]    As pointed out above, even with crossing grooves, the balls can drop out when torque is applied to one of the races. However this situation is avoided by both of the embodiments of the invention previously described.  
         [0044]    Referring first to the embodiment in FIGS. 1-15, there will be seen diagrammatically in FIGS. 12-15, the relationship of two crossing grooves  40  and  44  of a groove pair  48 , and two crossing grooves  42  and  46  of a groove pair  50 . All of the grooves are of uneven depth throughout their length due to the offset of the groove centers from the spherical center. In the perspective view of the groove pair  48  (FIG. 12), it will be seen that there is greater groove depth to the right than to the left. As the inner race groove  44  tends to rotate into the paper (as noted by the arrow  160  in the perspective view), the front wall of the inner race groove  44  will push the ball against the back wall of the outer race groove  40 . The forces from both groove walls will drive the ball to the right as shown in the front view. Since the grooves  40  and  44  have more depth to the right, nothing will stop movement of the balls to the right, except for the existence of the groove pairs  50 .  
         [0045]    Referring to the perspective view of the groove pair  50  (FIG. 14), it will be seen that the grooves  42  and  46  are of less depth to the right. Thus as the inner race groove  46  tends to rotate into the paper, the front wall of the inner race groove  46  will push the ball against the back wall of the outer race groove  42 . These forces shown in the front view will drive the ball to the right. But the ball cannot get through the narrower channel of the grooves  42  and  46 . The ball becomes locked in the crossing pair of the grooves  42 ,  46  and stops the rotation of the inner race groove relative to the outer race groove. Thus all of the groove pairs  50  will stop the relative rotation of all of the groove pairs  48  so that all balls will be contained in the crossing groove pairs. The outer race will thus rotate together with the inner race. It should be noted that in this case only the groove pairs  48  will carry the torque.  
         [0046]    Considering now the second embodiment in FIGS. 16-27, there is seen diagrammatically in FIGS. 24-27, the relationship of two crossing grooves  140  and  144  of a groove pair  148  and two crossing grooves  142  and  146  of a groove pair  150 . All inner race groove centers are offset symmetrically to one side of the sphere center and all outer race groove centers are offset symmetrically to the opposite side of the groove center, and the grooves in each race are alternately inclined in opposite directions.  
         [0047]    As seen in the front view of FIGS. 24 and 26, the inner race groove  144  of the groove pair  148  is inclined out of the paper, while the inner race groove  146  of the pair  150  are inclined into the paper. All of the outer race grooves  140  and  142  are symmetrically inclined in the opposite direction to their paired inner race grooves  146  and  148 .  
         [0048]    All groove pairs have less groove depth to the left and more depth to the right. Assuming that the inner race grooves tend to rotate into paper as indicated by the arrow  160 , then the front walls of the inner race grooves will tend to push the ball against the back walls of the outer race grooves. The forces tend to drive the ball of the groove pair  148  to the right, which is the direction of more groove depth. But the forces of groove pair  150  tend to drive the ball to the left, in which direction the crossed groove pair has less depth. Accordingly, the ball gets stuck and stops the relative rotation of the inner and outer races, so that the outer race rotates with the inner race.  
         [0049]    In both embodiments of the invention, the crossing groove pairs maintain the balls in a plane which bisects the angle of adjustment of the two races, and the speed of rotation of the two races remains always the same whatever the angular adjustment.