Tripod CV Joint Leg Shaft Projection for Roller Retention
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Solution Overview
Problem
Existing tripod type constant velocity universal joints of the double roller type face challenges in preventing the roller unit from coming off the leg shaft during assembly, repair, or when attaching/detaching the drive shaft, without compromising assemblability.
Innovation Solution
The tripod type constant velocity universal joint incorporates a projection on the leg shaft's outer peripheral surface, extending into the joint axial line direction, with a ratio of projection dimension to leg shaft dimension of 0.3 or more, enhancing the interference region with the inner ring to prevent the roller unit from coming off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a projection is provided on the leg shaft to prevent the roller unit from coming off, then the come-off preventing function is improved, but the assemblability between the roller unit and tripod member deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the projection dimensions (radial projecting amount and width in joint axial line direction) to specific ranges. The radial projecting amount is set to 0.01 to 0.1 times the outer diameter of the leg shaft, and the width is set to 0.1 to 0.5 times the outer diameter. These parameter adjustments create an interference region that prevents come-off while maintaining assemblability, resolving the contradiction between reliability and ease of manufacture.
2Reliability
If the radial projecting amount and width of the projection are increased to improve come-off prevention, then the come-off preventing function is improved, but it becomes difficult to incorporate the roller unit into the leg shaft
Solution Approach 1:
The patent resolves this contradiction by changing the parameters of the projection to specific proportional ranges rather than fixed large values. The radial projecting amount is set to 0.01 to 0.1 times the outer diameter of the leg shaft, and the width in the joint axial line direction is set to 0.1 to 0.5 times the outer diameter. These scaled parameters provide sufficient come-off prevention while maintaining ease of incorporation during assembly.
Data Source
AI summary
In a tripod type constant velocity universal joint of a double roller type, a projection 40 is provided in regions including both end portions in a direction orthogonal to a joint axial line O on a shaft end side with respect to an inner ring 12 on an outer peripheral surface of a leg shaft 32 of a tripod member 3. A ratio T/ag1 between a dimension T in a direction of the joint axial line O of the projection 40 and a major diameter ag1 of a contact portion with the inner ring on the outer peripheral surface of the leg shaft 32 is 0.3 or more.