Constant Velocity Joint Boot Stress Concentration Mitigation
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Solution Overview
Problem
Existing constant velocity joint boots fail to sufficiently suppress crack generation in the smaller cylindrical portion due to stress concentration when the bellows portion bends at small angles, leading to potential early cracks and reduced durability.
Innovation Solution
The constant velocity joint boot design incorporates a smaller cylindrical portion with a cylindrical surface, slant surface, and vertical wall surface formed continuously from the clamp groove, which alleviates stress concentration by increasing the surface area and effectively interrupting stress transmission from the bellows portion, thereby preventing crack generation at small angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bellows portion bends at small angles (20 degrees or smaller), then the joint portion can be sealed off, but stress concentration occurs in the smaller cylindrical portion causing crack generation
Solution Approach 1:
The invention applies local quality by creating a shoulder portion with a specific geometric configuration (cut-away portion) at the critical location where the smaller cylindrical portion meets the bellows portion. This localized structural modification concentrates the stress-relieving function at the specific area where crack initiation occurs, rather than uniformly thickening the entire smaller cylindrical portion. The cut-away portion 94 creates a stress distribution pattern that protects the vulnerable region while maintaining overall component integrity.
Solution Approach 2:
The shoulder portion 93 with cut-away portion 94 acts as a stress cushioning element that is built into the structure beforehand. When stress from small-angle bending occurs, this pre-designed feature absorbs and redistributes the stress before it can concentrate at the vulnerable boundary between the smaller cylindrical portion and bellows portion, preventing crack initiation in advance.
2Duration of action of stationary object
If a cut-away portion is formed on the shoulder portion to reduce stress, then durability is increased, but the volume of the shoulder portion is reduced
Solution Approach 1:
The cut-away portion 94 is a localized modification that affects only the specific region where stress concentration occurs at the shoulder portion. This local quality approach allows the invention to reduce stress at the critical interface without significantly impacting the overall volume or structural integrity of the smaller cylindrical portion. The modification is precisely targeted at the boundary region between the smaller cylindrical portion and bellows portion.
Data Source
AI summary
A smaller cylindrical portion having a clamp groove formed on an outer peripheral surface thereof has a cylindrical surface portion which extends straight in an axial direction, an inclined surface portion which extends, while being inclined, radially outwardly from an end portion of the cylindrical surface portion and a vertical wall surface portion which extends straight radially outwardly from an end portion of the inclined surface portion, the cylindrical surface portion, the inclined surface portion and the vertical wall surface portion being formed continuously sequentially in that order from a side wall surface of the clamp groove. A stress concentration on a specific location on the smaller cylindrical portion can be suppressed by virtue of the stress alleviating action of these cylindrical surface portion, the inclined surface portion and the vertical wall surface portion.