Method of Assembling Constant Velocity Joint of Tripod Type

Abstract

A method of assembling a constant velocity joint comprises: measuring a maximum non-interfering thickness of a trunnion that can be inserted into an inner roller without interference while inclining the inner roller by a predetermined degree; providing the trunnion to have a cross sectional shape, taken in a direction perpendicular to the trunnion, with a first thickness at one lateral side and a second thickness at the other lateral side, where one or both of the first and second thicknesses have a size the same as or 0-30% smaller than the maximum non-interfering thickness of the trunnion; inclining the inner roller to assume the predetermined degree of inclination; positioning the inclined inner roller onto the trunnion and completely assembling thereto without excessive external force.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This is a divisional application of U.S. patent application Ser. No. 11 / 947,307 filed on Nov. 29, 2007, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a constant velocity joint of tripod type, which is disposed between a drive shaft and a driven shaft coupled to each other and typically used in a drive axle of, for example, an automobile for transmitting rotational torque between the rotating shafts.BACKGROUND OF THE INVENTION[0003]Tripod type constant velocity joints are well known in the automobile industry as one type of constant velocity joints used in the drive system of automobiles to transfer a uniform torque and a constant speed, while operating with a wide range of joint angle. For instance, one example of the tripod type constant velocity joint was illustrated in Japanese Patent Application, S62-233522 as shown in FIGS. 1-2. This tripod type constant veloc...

AI Technical Summary

Benefits of technology

The present invention provides improved constant velocity joints and methods of assembly and lubrication for the joints. The joints have plural trunnions with reduced contact surfaces and cylindrical protrusions to reduce frictional spinning force and rolling resistance. The joints also have a durable structure and are easy to assemble. The invention also includes a tripod type constant velocity joint with enhanced mechanical strength and durability. The joints have sufficient lubrication mechanisms to minimize the rolling resistance when rotating with any joint angle present. The invention provides a solution for improving the performance of constant velocity joints in the market.

Problems solved by technology

Thus, a relatively large friction occurs between the faces.

Hence it is difficult for the roller assembly 19 to be smoothly rolled, and causes a significant rolling resistance.

Moreover, for manufacturing the constant velocity joint of FIG. 3, there are considerable difficulties not only to machine a complex spherical surface defined by a curvature of a longitudinal cross-section of the trunnion 18′ formed by radius r2 and R and the ellipse shape 18′ defined as a longer diameter A and a shorter diameter B, but also to measure the trunnion 18′ having a complex three dimensional profile, in terms of both inspection and quality control.

These difficulties cause the contact pattern mentioned above to be inconsistent in terms of quality, which leads to high costs in manufacturing perspective and also to potential quality control issues.

However, due to the relative pivotal movement of the trunnion 18′ within the open inner surface of the inner roller 19b, the grease flows out easily from the open space “s” and sufficient amount of grease cannot be retained in the open space “s” disposed between the spherical face of the trunnion 18′ and the upper and lower ends at the inner face of the inner roller 19b. As a result, the joint cannot be lubricated effectively and often suffers aggravated friction problems.

This becomes more problematic when the grease is in high density condition, for example, during the initial driving stage of automobile particularly at a cold outside temperature, which causes a significant rolling resistance in the drive system.

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