CV Joint Boot With Flanges And Grommet For Sealing
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Solution Overview
Problem
Existing boots for constant velocity universal joints face challenges in maintaining sealing ability and operability due to low elasticity of thermoplastic elastomer materials, difficulty in forming noncircular shapes, and poor fitting completion feelings during assembly, which affects the durability and sealing effectiveness.
Innovation Solution
The boot design features a major-diameter cylinder with axially extending flanges and radially protruding positioning protrusions that engage with concavities on the mating member, allowing for easy deformation and secure fitting, while maintaining sealing ability through strategically placed sealing protrusion rims and a grommet with a softer material for enhanced sealing and reduced assembly resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the major-diameter cylinder is molded to conform to noncircular mating member surface, then sealing ability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention divides the sealing function into two segments: the boot body molded by blow molding with a circular cross-section, and the grommet molded separately to conform to the noncircular mating member surface. This segmentation allows each part to be manufactured using appropriate methods, reducing overall manufacturing complexity while maintaining sealing ability.
Solution Approach 2:
The grommet acts as an intermediary element between the boot body and the noncircular mating member. It provides the necessary conformal sealing surface without requiring the boot body itself to be molded with complex noncircular geometry, thus simplifying boot body manufacturing.
2Manufacturing precision
If positioning protrusions are formed on the boot, then positioning accuracy is improved, but assembly resistance increases
Solution Approach 1:
The invention uses the flexible grommet to accommodate the positioning protrusions. The grommet's elasticity allows it to deform during assembly, reducing the resistance force, while still achieving accurate positioning when the protrusions engage with the mating member's recesses.
Solution Approach 2:
The invention changes the material parameter of the grommet to a softer, more elastic rubber material that can deform under assembly force. This allows the positioning protrusions to be installed with lower resistance while maintaining positioning accuracy through the engagement of protrusions with mating recesses.
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 design achieves improved sealing performance, reduced assembly resistance, and a clear fitting completion feeling, ensuring secure positioning and durability of the boot around the mating member, while maintaining the boot's sealing ability and reducing manufacturing complexity.
Implementation Method 1
a fastening force resulting from clamping is transmitted to the grommet by way of the boot body's major-diameter cylinder, and thereby the grommet deforms elastically to closely adhere to a mating member
Implementation Method 2
since the bellows deforms depending on the change of angles (i.e., joint angles) between the joint outer race and the shaft, it is possible to securely seal the joint part of the constant velocity universal joint with the boot
Data Source
AI summary
A boot for a constant velocity universal joint includes a minor-diameter cylinder, a major-diameter cylinder, and a bellows. The major-diameter cylinder includes a sealing protrusion rim, a plurality of flanges, and positioning protrusions. The sealing protrusion rim is formed on an inner peripheral surface of the major-diameter cylinder. The flanges are disposed at intervals in a peripheral direction of the major-diameter cylinder, and extend axially outward from an opposite end surface of the major-diameter cylinder. The positioning protrusions protrude from the flanges radially toward an inner peripheral side of the major-diameter cylinder, and are to be engaged with concavities formed in an outer peripheral surface of the mating member. The boot maintains the sealing ability high, and at the same time can reduce the resistance during its fitting around a mating member, and can furthermore produce a fitting completion feeling when the fitting is completed.