Constant-Velocity Universal Joint Ball Groove Geometry
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Solution Overview
Problem
Conventional constant-velocity universal joints with high-articulation angles experience significant power loss due to an inefficient ratio of offset value O to distance H, which is typically within the range of 0.13 to 0.15.
Innovation Solution
The design optimizes the ratio O/H by adjusting the offset value between the inflection point of the outer ball groove and the line connecting torque transmitting ball centers, and the distance between the inner joint member center and the torque transmitting ball, within a range of 0.07 to 0.11, allowing for enhanced power transmission efficiency while preventing locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ratio O/H is within the conventional range of 0.13 to 0.15, then the high-articulation angle (more than 50 degrees) is achieved, but significant power loss occurs
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio O/H from the conventional range of 0.13-0.15 to the new range of 0.07-0.11. This specific parameter modification in the ball groove geometry fundamentally changes the power transmission characteristics, reducing power loss while preserving the high articulation angle capability of more than 50 degrees.
2Loss of energy
If the ratio O/H is reduced to 0.07 to 0.11, then power transmission efficiency is enhanced, but locking may occur
Solution Approach 1:
The patent carefully selects the O/H ratio range of 0.07-0.11 as an optimal parameter change that simultaneously achieves reduced power loss and prevents locking. This precise parameter optimization ensures that the ball groove geometry maintains reliable operation at high articulation angles while improving power transmission efficiency by approximately 5%.
Solution Approach 2:
The patent applies local quality by specifically modifying the ball groove geometry through the O/H ratio optimization. This localized change in the groove shape affects the contact characteristics between the torque transmitting balls and the grooves, enabling improved power transmission without causing locking, while other parts of the universal joint remain unchanged.
3Ease of manufacture
If the inflection point is offset toward the open side, then manufacturing and assembly are simplified, but precision may be affected
Solution Approach 1:
The patent applies asymmetry by offsetting the inflection point of the ball groove toward the open side of the outer joint member. This asymmetric design simplifies manufacturing and assembly processes while the carefully controlled O/H ratio ensures that the essential geometry precision is maintained for reliable operation.
Data Source
AI summary
A constant-velocity universal joint includes: an outer joint member having a plurality of outer ball grooves; an inner joint member having a plurality of inner ball grooves; a plurality of torque transmitting balls; and a ball cage. The outer ball groove and the inner ball groove respectively have a double shape, and a ratio O/H of an offset value O which is a distance between an inflection point of the outer ball groove and a line connecting centers of the torque transmitting balls in a state that the outer joint member and the inner joint member form 0 angle and a distance H between a center line of the inner joint member and a center of the torque transmitting ball in a state that the outer joint member and the inner joint member form 0 angle is within a range of 0.07 to 0.11.