Tripot universal joint

Abstract

A telescopic tripot universal joint comprises an outer drive member having three longitudinal drive channels which include two opposing concave side surfaces, an inner drive member having three radial trunnions having a radially outward facing semi-spherical surface for tiltably mounting a drive ball assembly which has a bearing train disposed radially between an inner ball tiltably engaged to the trunnion and an outer ball having a tread face which directly opposes the concave side surfaces of the drive channels. The ball assembly being free to wobble about a Z-axis wherein the assembly pivots about an X-axis disposed laterally to the outer drive member and pivots about a Y-axis disposed longitudinally to the outer drive member. The channel carries a guide rail which extends longitudinally lengthwise to the channel and projects radially inward in order to contact the outer ball when the ball assembly pivots about the X-axis, i.e., tilts relative to the axis of the outer drive member.

1. A tripot universal joint comprising:
 an outer drive member having a first longitudinal axis and three longitudinal drive channels disposed parallel to the longitudinal axis and equally spaced circumferentially from one another, each one of the three longitudinal drive channels defined by two opposing concave side surfaces and a back surface, the back surface of each drive channel facing radially inward with respect to the outer drive member, the opposing concave side surfaces of each drive channel disposed parallel to one another and separated circumferentially with respect to the outer drive member by the back surface of that drive channel;  
 an inner drive member having a second longitudinal axis and three radial trunnions equally spaced circumferentially from one another and on respective coplanar radial axes which intersect the second longitudinal axis at a spider center, each one of the three trunnions having a circular  convex surface disposed in the  a respective one of the longitudinal drive channels and being in confronting relation with the opposing concave surfaces of said respective one of the longitudinal drive channels of the outer drive member;  
 three ball assemblies, each said ball assembly constructed and arranged to rotate and wobble about the radial axis of the  a respective one of the trunnions, each one of the three  said ball assemblies  assembly contacting and encircling the circular  convex surface of the  its respective trunnion, and  each said ball assembly having a semi-spherical outer ball being in rolling contact with one of the two opposing concave side surfaces of a said drive channel of the outer drive member, each said outer ball having a central axis about which it rotates and a radial side wall facing radially outward with respect to the outer drive member; and wherein  
 the back surface of the  each said drive channel having  has a guide rail projecting radially inward and extending longitudinally lengthwise to the channel, the guide rail being spaced circumferentially between the two opposing side surfaces so that  of the channel, the radial side wall of the  each outer ball contacts the  contacting its respective guide rail longitudinally  at one of two spaced positions along the guide rail  positions longitudinally spaced therealong at one of two locations on said outer ball radial side wall depending upon the direction the ball assembly tilts relative to and along said first longitudinal axis of said outer drive member as it pivots about an X-axis disposed coplanar to the radial axes of the three trunnions and disposed perpendicular to the radial axis of the respective trunnion, said two locations on the side wall being on opposite sides of said outer ball central axis.  
 
     
     
       2. The tripot universal joint set forth in  claim 1  comprising:
 each one of the opposing side surfaces having a lateral cross section profile having a radius; and  
 the ball assembly having a maximum radius, wherein the radius of the side surface profile is substantially equal to the maximum radius of the ball assembly.  
 
     
     
       3. The tripot universal joint set forth in claim  2    1  wherein the guide rail is centered along the back surface. 
     
     
       4. The tripot universal joint set forth in claim  3    1 , wherein comprising:
 the ball assembly having a center line about which the  each said outer ball rotates, the center line being co-linear to  central axis is collinear with the radial axis of the respective trunnion when the first longitudinal axis of the outer drive member is co-linear to  collinear with the second longitudinal axis of the inner drive member; and  
 theeach said outer ball havinghas a radially outward facing semi-spherical tread face engaged to one of the respective two opposing side surfaces, the radius of the ball assembly extending radially outward from a center point of the ball assembly lying along the center lineouter ball central axis and to the tread face.  
 
     
     
       5. The tripot universal joint set forth in claim  4    1  wherein each one of the three roller  ball assemblies has a bearing train disposed radially between the trunnion and the outer roller. 
     
     
       6. The tripot universal joint set forth in  claim 5  wherein each one of the three roller  ball assemblies has a semi-spherical  an inner ball disposed radially between the trunnion and the bearing train. 
     
     
       7. The tripot universal joint set forth in  claim 6  wherein the circular  convex surface of the trunnion is semi-spherical and slideably  slidably engages and conforms to an annular concave mating surface of the inner ball. 
     
     
       8. The tripot universal joint set forth in  claim 7  wherein the bearing train is a series of needle bearings disposed directly between a cylindrical inner surface of the outer ball and a cylindrical outer surface of the inner ball. 
     
     
       9. The tripot universal joint set forth in  claim 8  wherein the outer ball has two thrust shoulders projecting radially inward from the cylindrical inner surface of the outer ball, the series of needle bearings being disposed axially between the two thrust shoulders with respect to the center line of the ball assembly. 
     
     
       10. The tripot universe  universal joint set forth in  claim 9  comprising:
 each one of the longitudinal drive channels of the first drive member having two guide walls extending lengthwise longitudinally along the channel and projecting radially inward from and defined by the back surface, the guide walls being spaced circumferentially apart; and  
 wherein the outward radial side wall of each one of the outer balls contact  contacts one of the guide walls carried within the respective channels of the outer drive member when the ball assembly pivots about a Y-axis disposed substantially parallel to the respective channel and interesting  intersecting transversely the X-axis.  
 
     
     
       11. The tripot universal joint set forth in  claim 1  comprising:
 each one of the longitudinal drive channels of the first drive member having two guide walls extending lengthwise longitudinally along the channel and projecting radially inward from and defined by the back surface, the guide walls being spaced circumferentially apart; and  
 wherein the outward radial side wall of each one of the outer balls contact  contacts one of the guide walls carried within the respective channels of the outer drive member when the ball assembly pivots about a Y-axis disposed substantially parallel to the respective channel and interesting  intersecting transversely the X-axis.  
 
     
     
       12. The tripot universal joint set forth in  claim 11  comprising:
 each one of the opposing side surfaces having a lateral cross section profile having a radius; and  
 the ball assembly having a maximum radius, wherein the radius of the side surface profile is substantially less than the maximum radius of the ball assembly.  
 
     
     
       13. The tripot universal joint set forth in  claim 12  wherein the first guide wall forms contiguously into the first side surface and the second guide wall forms contiguously into the second side surface. 
     
     
       14. A tripot universal joint comprising:
 an outer drive member having a first longitudinal axis and three longitudinal drive channels disposed parallel to the longitudinal axis and equally spaced circumferentially from one another, each one of the three longitudinal drive channels defined by opposing concave first and second side surfaces and a back surface, the back surface of each drive channel facing radially inward with respect to the outer drive member, the first and second side surfaces of each drive channel disposed parallel to one another and separated circumferentially with respect to the outer drive member by the back surface of that drive channel;  
 the first and second side surfaces each having a lateral cross section profile having a radius;  
 an inner drive member having a second longitudinal axis and three radial trunnions equally spaced circumferentially from one another and on respective coplanar radial axes which intersect the second longitudinal axis at a spider center, each one of the three trunnions having a circular  convex surface disposed in the  a respective one of the longitudinal drive channels and being in confronting relation with the opposing concave side surfaces of said respective one of the longitudinal drive channels of the outer drive member;  
 three ball assemblies, each said ball assembly constructed and arranged to rotate and wobble about the radial axis of the  a respective one of the trunnions, each one of the three  said ball assemblies  assembly contacting and encircling the circular  convex surface of the  its respective trunnion, and having a radius, each said ball assembly having a semi-spherical outer ball being in rolling contact with one of the two opposing concave side surfaces of a said drive channel of the outer drive member and a radial side wall facing radially outward with respect to the outer member, each said outer ball having a central axis, the radius of the ball assembly being substantially equal to the radius of the first and second side surface profiles; and  
 the back surface of the  each said drive channel having a guide rail projecting radially inward and extending longitudinally lengthwise to the channel, the guide rail of said drive channel being centered and spaced circumferentially between the two opposing side surfaces of said drive channel so that the side wall of the respective outer ball contacts positions along the length of the guide rail when  at one of two locations on the side wall depending upon the direction the ball assembly tilts relative to and along said first longitudinal axis of said outer drive member as it pivots about an X-axis disposed coplanar to the radial axes of the three trunnions and disposed perpendicular to the radial axis of the respective trunnion, said two locations on the side wall being on opposite sides of the respective outer ball central axis.