CV Joint Boot Seal Structure for Dust and Debris Exclusion

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Solution Overview

Problem

Constant velocity joints in vehicles face seal failure due to environmental challenges such as dirt, debris, and harsh conditions, leading to premature joint failure in off-road and demanding applications.

Innovation Solution

A semi-rigid, flexible plastic boot with a retaining ring and O-ring seal system that provides a reliable, easy-to-install, and maintainable primary seal with a significant flexing capability, adapted for use in various vehicles and environments, including off-road and water vehicles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional seal is used in constant velocity joints, then the joint can operate in normal automotive environments for thousands of miles, but the seal fails prematurely in environmentally demanding applications such as off-road and water vehicles

Engineering Contradiction:

Improveseal durabilityVSAvoidenvironmental damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a flexible boot made of elastomeric material that envelops the constant velocity joint, creating a protective membrane barrier. This flexible shell conforms to the joint's movements while maintaining sealing integrity, protecting against environmental contaminants in harsh conditions including off-road and water vehicle applications

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The seal system combines multiple materials with complementary properties: an elastomeric boot for flexibility and environmental resistance, and a durometer-hard seal member for structural sealing. This composite approach creates a seal system that withstands both normal and harsh environmental conditions

Inventive Principle:

Principle #40Composite materials

2Reliability

If a more robust seal system is implemented to withstand harsh environments, then the seal reliability improves, but the device complexity and installation difficulty increase

Engineering Contradiction:

Improveseal performance in harsh environmentsVSAvoidseal system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal system is divided into distinct functional components: a flexible boot for environmental protection and a separate durometer-hard seal member for primary sealing. This segmentation allows each component to be optimized for its specific function while simplifying the overall assembly and installation process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal member is positioned within the boot structure, with the boot enveloping the joint and the seal member nested within it. This nested arrangement provides layered protection while maintaining a compact overall structure that does not significantly increase device complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If the seal is designed for maximum sealing capability, then the protection against dirt and debris improves, but the flexing capability of the joint is reduced

Engineering Contradiction:

Improvesealing effectivenessVSAvoidjoint flexing capability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The elastomeric boot acts as a flexible membrane that can accommodate the joint's angular movements and flexing up to 40 degrees while maintaining its sealing function. The flexibility of the boot material allows it to conform to the joint's range of motion without compromising the seal

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The seal member's durometer hardness is specifically selected to provide adequate sealing pressure while allowing sufficient flexibility for joint movement. This parameter optimization ensures the seal remains effective across the joint's full operating range without restricting flexing capability

Inventive Principle:

Principle #35Parameter changes

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

Enhances the durability and reliability of constant velocity joints by effectively sealing against dust and debris, reducing the likelihood of joint failure in harsh environments while maintaining ease of installation and maintenance.

Implementation Method 1

a boot made from an elastomeric material...seals against dust and debris

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

a durometer-hard seal member positioned within the boot...seals against dust and debris

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS11536320B2Seal for a constant velocity joint

Publication Date: 2022.12.27 AIRCRAFT GEAR CORP

AI summary

A constant velocity universal joint includes a body which encloses the constant velocity joint components and provides a smooth outer surface. A semi-rigid plastic boot has a spherical surface sized to generally match the outer surface of the body. The material of the boot is sufficiently elastic to allow the boot to fit over the body, yet sufficiently resilient to snap the open end closed after the boot is placed over the body to provide a substantial seal preventing entry of debris under the seal. A retaining ring is positioned on the boot near the truncated end, the ring establishing the location of an elastic seal that contacts the outer surface of the body.