Patent ID: 8251827

Claim:
A constant velocity joint for a drive system having a first rotating shaft and a second rotating shaft coupled with the constant velocity joint, the constant velocity joint comprising: a hollow housing having a plurality of guide grooves therein, the guide grooves extending in an axial direction of the housing and spaced equally apart in a circumferential direction of the housing; a tripod having a plurality of trunnions, each trunnion positioned in a corresponding one of the guide grooves of the hollow housing; and a roller assembly including an inner roller, the inner roller having a spherical inner face for receiving a corresponding one of the trunnions therein, and an outer roller mounted on an outer face of each inner roller, the roller assembly for transmitting a load between the first and second rotating shafts to drive the driving system; wherein each trunnion includes two opposing spherical contact surfaces disposed in the directions subject to the load, and two opposing side surfaces disposed between the two opposing spherical contact surfaces and in the directions perpendicular to the spherical surfaces and not subjecting to the load; wherein a first cross sectional shape of the trunnion, the first cross section taken at an upper portion of the trunnion and in a direction perpendicular to the longitudinal axis of the trunnion, has a thickness larger than a maximum non-interfering thickness of the trunnion at a first lateral side, and the thickness is gradually decreased until it reaches a thickness the same as or 0-30% smaller than the maximum non-interfering thickness of the trunnion at a second lateral side opposite to the first lateral side of the trunnion, the maximum non-interfering thickness measured with the inner roller inclined by a predetermined degree relative to the longitudinal axis of the trunnion to assemble the trunnion into the inner roller without interference; wherein a second cross sectional shape of the trunnion, the second cross section taken at a lower portion of the trunnion and in a direction perpendicular to the longitudinal axis of the trunnion, has a thickness the same as or 0-30% smaller than the maximum non-interfering thickness of the trunnion at the first lateral side of the trunnion, and the thickness is gradually increased until it reaches a thickness larger than the maximum non-interfering thickness of the trunnion at the second lateral side of the trunnion; wherein cross-sectional shapes in-between the upper and lower portions are gradually varied from the cross-sectional shape at the upper portion to the cross-sectional shape at the lower portion of the trunnion.