CV Joint Boot Shoulder Geometry for High-Angle Durability
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Solution Overview
Problem
Existing boots for constant velocity universal joints face durability and fatigue issues when operating at high angles, particularly exceeding 50 degrees, due to increased stress, interference, and reduced film length, which limits their ability to support quick vehicle turns and expanded cabin space demands.
Innovation Solution
A boot design featuring two small crest portions on the large-diameter side to prevent interference with the clamp, extended film length to alleviate tensile stress, and increased curvature radii of crest and trough portions to reduce stiffness, allowing for improved deformation and stress relaxation at high operating angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boot is designed with a tapered shoulder portion to improve folded shape and durability, then the durability is improved, but the film length is reduced causing increased tensile stress and fatigue
Solution Approach 1:
The patent applies curvature by forming auxiliary crest portions with specific radial distances and diameters. The curved geometry of these crest portions allows the boot to deform smoothly at high operating angles without creating stress concentration points, thereby maintaining film length while improving durability through controlled deformation patterns.
Solution Approach 2:
The patent changes geometric parameters by setting specific relationships between radial distances (H1 shorter than H2) and diameters (D1 larger than D3). These parameter changes optimize the deformation behavior of the boot at high operating angles, allowing the auxiliary crest portions to overlap radially and prevent interference while maintaining sufficient film length.
2Adaptability or versatility
If the boot operates at high angles, then the turning ability is improved, but the pleats contact each other causing wear and reduced durability
Solution Approach 1:
The patent segments the shoulder portion into multiple auxiliary crest portions (first and second auxiliary crest portions) with different radial distances. This segmentation allows different parts of the shoulder portion to deform independently at high operating angles, preventing pleat contact and wear while maintaining the required turning ability.
Solution Approach 2:
The patent utilizes radial overlap of auxiliary crest portions as an additional dimension of deformation control. By designing the crest portions to overlap in the radial direction at high operating angles, the patent creates a new deformation mode that prevents pleat contact while accommodating large turning angles.
3Ease of operation
If the curvature radii of crest and trough portions are increased to reduce stiffness, then the deformation ability is improved, but the structural strength may be reduced
Solution Approach 1:
The patent applies local quality by giving different curvature radii to different portions of the boot. The auxiliary crest portions have larger curvature radii to enable deformation, while the overall boot structure maintains sufficient strength through the specific geometric relationships (H1 < H2 and D1 > D3) that distribute stresses appropriately across the structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The boot achieves enhanced durability and fatigue resistance even at super high operating angles, preventing wear and interference, and maintaining structural integrity for high-angle operations.
Implementation Method 1
a boot for a constant velocity universal joint, which has such a deformation mode that, when the constant velocity universal joint forms a high operating angle, auxiliary crest portions overlap one another in a radial direction of the boot
Implementation Method 2
The boot achieves enhanced durability and fatigue resistance even at super high operating angles
Data Source
AI summary
A boot for a constant velocity universal joint includes large- and small-diameter mounting portions to be mounted to an outer joint member and a shaft, respectively, with boot clamps, a bellows portion integrally coupling the large- and small-diameter mounting portions to each other, and a cylindrical shoulder portion formed at a bellows portion-side end of the large-diameter-side mounting portion, and connected to the bellows portion through two auxiliary crest portions and one auxiliary trough portion between the auxiliary crest portions. A radial distance between each of the auxiliary crest portions and the auxiliary trough portion is shorter than a radial distance between a crest portion and a trough portion. A diameter passing through a center of the radial distance between each of the auxiliary crest portions and the auxiliary trough portion is larger than a diameter of the cylindrical shoulder portion.