Constant velocity joint

Details Constant velocity joint Constant velocity joint

1998-11-25

2001-02-13

Browne, Lynne H. (Department: 3629)

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Coupling accommodates drive between members having...

Coupling transmits torque via radially spaced ball

C464S143000

Reexamination Certificate

active

06186899

ABSTRACT:

TECHNICAL FIELD
The technical field of this invention is a constant velocity joint.
BACKGROUND OF THE INVENTION
A well known constant velocity joint, used in the drive axles of front wheel drive motor vehicles, is the “Rzeppa” joint, described in U.S. Pat. No. 2,046,584, in which a driving member and a driven member transmit torque through a plurality (generally 6) of balls captured in longitudinal grooves in the driving and driven member and a cage. The geometry of the arrangement ensures that the balls are always aligned in a plane which bisects the angle between a pair of planes normal to the driving and driven axes of rotation; and constant velocity rotation of the driven member is thus assured, regardless of the joint angle between driving and driven members. As the joint angle increases, however, some portion of the driven member, usually the output shaft, eventually abuts some portion of the driving member to define a maximum joint angle. A variety of design factors and constraints work together to limit this maximum joint angle, and considerable effort has been expended in attempting to increase it. Such increases in maximum joint angle have generally come at the cost of an increase in joint package size, which is not desirable in the crowded engine compartments of front drive vehicles.
A modification of the original “Rzeppa” design is shown in U.S. Pat. No. 3,879,960 to Welschof et al. The constant velocity joint of this design is undercut-free: that is, the grooves of the outer joint member have a radial profile at the open end which is parallel to the joint axis so that they are not undercut in the longitudinal direction. The undercut-free design of this reference provides a reasonably high maximum joint angle; but an even higher joint angle is desired.
SUMMARY OF THE INVENTION
The constant velocity joint of this invention provides an increase in maximum joint angle, relative to similarly constructed joints of the prior art, without a corresponding increase in joint package size. Thus, for any desired maximum joint angle, the constant velocity joint of this invention allows a smaller joint package size than a similarly constructed joint of the prior art.
The constant velocity joint of this invention has a modified radial groove profile which significantly decreases ball movement radially inward of the ball center radius so that the ball cage may be increased in diameter without a corresponding increase in ball center radius. The radial groove profile provides a required predetermined funnel angle for ball control at the ball centered point of contact but minimal change in distance from the joint center over most of the axially inner side of the grooves in the outer joint member. One embodiment provides a circular arc centered on the joint center axially inward of the ball center point of contact, a circular arc centered on a point offset from the joint center on the axially outer side of the ball centered point of contact and a straight line on the axially inner side of the ball centered point of contact joining and tangent to both arcs. Another embodiment provides an elliptical profile based on a major axis centered on the joint center and angled with respect to the joint axis to provide a predetermined funnel angle when the joint angle is zero. The joint structure is applicable to both undercut and undercut-free designs and provides an increase in maximum joint angle in either.


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Rzeppa; UNIVERSAL JOINT DRIVES; Apr. 1953; pp. 162-170 MACHINE DESIGN.
Miller; CONSTANT VELOCITY UNIVERSAL BALL JOINTS-THEIR APPLICATION IN WHEEL DRIVES; Society of Automative Engineers, INTERNATIONAL AUTOMOTIVE ENGINEERING CONGRESS, JAN. 11-15, 1965.

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