JP2002195283A - Constant velocity ball race having polygonal contact face - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball race in which stress is reduced, its dimensional stability is enhanced and backlash is decreased. SOLUTION: This ball race (12) for a constant velocity ball joint (10) comprises an outer face (40) having a plurality of spline faces (44) to be engaged with ball elements and a polygonal inner face (42) to be engaged with a drive shaft (14). The distance between the above outer face and inner face is approximately constant over the whole periphery of the ball race.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates generally to a ball race for a constant velocity universal joint, and more particularly, to a ball race having an improved contact surface with a communication shaft.

[0002]

BACKGROUND OF THE INVENTION Constant velocity joints (CV joints) are used in a variety of applications requiring torque transmission through variable angles. While there are various configurations of CV joints, one known configuration utilizes a ball race mounted on a drive shaft to transmit torque through a variable angle portion.

[0003] Ball races generally have an outer surface formed to engage a ball element and an inner surface formed to engage a drive shaft. The outer surface is generally formed as a spline, while the inner surface is often cylindrical. As a result of the combination of these shapes, some parts of the ball race may be thinner and have correspondingly higher stresses. As a result of the presence of high stress regions in the ball race, the durability of the ball race may be reduced.

[0004] The central cylindrical portion of a ball race is often formed through a process known as broaching. In the broaching process, the tool is pulled through the middle of the ball race to form a cylinder and teeth that engage the drive shaft. However, broaching is known to have poor dimensional stability. Poor dimensional stability may further reduce the wall thickness between the outer and inner surfaces of the ball race, increasing stress and reducing durability.

[0005] Finally, it is known that backlash often occurs in ball races having a cylindrical central portion. Backlash occurs when the drive shaft moves before engaging the ball race during operation of the CV joint. It is known that backlash can create undesirable stresses in the ball race and can damage the connection between the drive shaft and the ball race.

[0006]

Therefore, there is a need for a ball race with reduced stress, increased dimensional stability, and reduced backlash.

[0007]

FIG. 1 is an exploded view of a constant velocity joint 10 using an embodiment of a ball race 12 according to the present invention. The constant velocity joint 10 is shown for illustrative purposes only, and the description is not intended to limit the invention. The constant velocity joint 10 includes a drive shaft 14, a stop ring 16, a retaining ring 18, a small boot clamp 20, a boot 24, a large boot clamp 26, a ball race 12, a plurality of ball elements 28, a bearing cage 30, an outer race 32, And a shaft assembly 34. CV joint 10
Although various elements have been shown to exemplify the typical arrangement, it is understood that various structures of the CV joint 10 using the ball race 12 are conceivable.

FIG. 2 is a diagram of an embodiment of a ball race 12 according to the present invention. Ball race 12 has an outer surface 40 and an inner surface 42. The outer surface 40 includes a plurality of ball elements 2
8 has a plurality of splined surfaces 44 that are each used to engage one of them. The shape and formation of the spline surface 44 is well known in the art. Spline surface 44
Can be formed using various forming methods, but is generally formed by machining.

By using the polygonal inner surface 42,
The thin area commonly found in existing structures utilizing cylindrical holes is reduced. The polygonal inner surface 42 has a more uniform wall thickness and therefore provides higher strength and longer fatigue life. In addition, experiments have shown that the use of the polygonal inner surface 42 with a driveshaft having a polygonal mating surface 46 as shown in FIG. 1 reduces backlash. When the backlash is reduced, the stress generated in the ball race 12 is reduced, and the fatigue life is further extended.

The polygonal inner surface 42 shown in FIG. 2 is illustrated as having a concave curved surface 48.
The use of these concave curved surfaces 48 can further increase wall thickness, resulting in lower stress and longer fatigue life. Although the polygonal inner surface 42 is shown with a concave curved surface 48, it should be understood that in alternative embodiments, the polygonal inner surface 42 may be formed as a convex, planar or other embossed surface. . Further, while six surfaces are illustrated on the polygon inner surface 42, in alternate embodiments the number of surfaces may be less or more than six.

Although the polygonal inner surface 42 may be formed in the ball race 12 in a variety of ways, in one embodiment, the polygonal inner surface 42 is formed using polygon forming techniques. Polygon forming technology is disclosed in U.S. Pat. No. 4,651,5.
This is a known technique disclosed in Japanese Patent Application No. 99-99. The use of polygon forming techniques to form the polygon inner surface 42 provides higher dimensional stability than prior methods such as broaching. This further ensures sufficient thickness of the ball race 12 and further reduces backlash accidents.

While the invention has been described in connection with one or more embodiments, the specific features and techniques described are:
It is merely an illustration of the principles of the invention, and many variations of the described method and apparatus may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

[Brief description of the drawings]

FIG. 1 is an exploded view of a constant velocity joint using an embodiment of a ball race according to the present invention.

FIG. 2 is a perspective view of a ball race for a constant velocity joint according to a preferred embodiment of the present invention.

[Explanation of symbols]

 12 ball race 14 drive shaft 28 ball element 40 outer surface 42 inner surface 44 spline surface 48 concave curved surface

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor M. Scott Johnson United States of America 48462 Ortonville Norris Drive 420 (72) Inventor Robert F. Keller United States of America 48047 Chesterfield Lancaster Driving 28546

Claims (2)

[Claims] 1. A constant velocity having a drive shaft and a plurality of ball elements, comprising: an outer surface having a plurality of spline surfaces engageable with a plurality of ball elements; and a polygonal inner surface engageable with a drive shaft. Ball race for joints. 2. The system of claim 1, wherein the distance from the inner surface to the outer surface is substantially constant around the periphery of the ball race.
Ball race described in.