CV Joint Alternating Pinch Angles for Smooth Cage Pivoting
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Solution Overview
Problem
Conventional constant-velocity universal joints face issues with insufficient pressing force at certain joint angles, leading to noise and delayed pivot movement due to the pinch angles' dependence on joint angle changes, which affects the smooth operation of the cage and ball interaction.
Innovation Solution
The design incorporates three first groove portions with a larger pinch angle and three second groove portions with a smaller pinch angle, alternately arranged, where the absolute value of the pinch angle in the first groove portions is greater than in the second groove portions by 2-10 degrees, ensuring a consistent and sufficient pressing force is maintained across various joint angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the pinch angle is increased in all groove portions, then the pressing force on balls is improved, but the device complexity increases due to symmetric configuration requirements
Solution Approach 1:
The patent applies local quality by differentiating the pinch angles in different groove portions. Specifically, first groove portions have a first pinch angle while second groove portions have a second pinch angle that differs from the first. This allows each groove portion to be optimized locally for its specific functional requirements, with some groove portions having larger pinch angles for greater pressing force while others have smaller pinch angles for reduced complexity.
2Adaptability or versatility
If the pinch angle varies with joint angle changes, then the pressing force adapts to different operating conditions, but noise and delayed pivot movement occur when pressing force is insufficient
Solution Approach 1:
The patent implements periodic action through the alternating arrangement of first groove portions and second groove portions around the centerline. As the joint rotates through different angles, balls periodically encounter groove portions with different pinch angles, ensuring that at least some balls always experience sufficient pressing force. This periodic variation in groove geometry prevents the continuous noise and delay problems that would occur with uniform groove designs.
3Stability of the object's composition
If symmetric groove portions are arranged about the centerline, then the universal joint maintains balanced performance, but the pressing force becomes insufficient at certain joint angles and phases
Solution Approach 1:
The patent introduces asymmetry by configuring second groove portions with a different pinch angle than first groove portions. While the groove portions are alternately and symmetrically arranged about the centerline, the asymmetric pinch angle values create differential pressing forces. This asymmetric design ensures that during joint rotation, balls in second groove portions receive enhanced pressing force when balls in first groove portions would otherwise experience insufficient force, thereby maintaining balanced overall performance across all joint angles.
Data Source
AI summary
A constant-velocity universal joint including a generally cup-shaped outer joint member and an inner joint member that cooperate with each other to define first and second groove portions. A pinch angle by which a ball is pinched in the first groove portion is open toward an opening end of the outer joint member. A pinch angle by which the ball is pinched in the second groove is open toward a bottom wall of the outer joint member. An absolute value of the pinch angle in the first groove portion is larger than an absolute value of the pinch angle in the second groove portion in a reference state in which centerlines of the outer joint member and the inner joint member lie in a straight line.