Overmoulded CVJ Boot with Radial Transition

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Solution Overview

Problem

Constant velocity joints face issues with lubricant leakage and contamination due to the expansion and contraction of flexible boot covers, which require additional seals and vents, increasing manufacturing complexity and reducing joint life.

Innovation Solution

A boot assembly where a flexible boot is molded directly to a boot-can with a radially extending transition portion, eliminating the need for external seals and vents by creating a sealed interface between the boot-can and the joint, using materials like rubber or thermoplastic elastomers for durability and bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional boot cover assembly with separate seals and vents is used, then the joint can accommodate expansion and contraction, but manufacturing complexity increases and joint life decreases due to lubricant leakage and contamination

Engineering Contradiction:

Improvejoint lifeVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the boot cover, seal, and vent functions into a single integrated boot assembly. The boot is molded directly onto the mounting can as one piece, eliminating separate seal components and vent holes. This integration reduces the number of parts, simplifies manufacturing, and eliminates potential failure points from multiple components while maintaining the ability to accommodate expansion and contraction.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated boot assembly performs multiple functions simultaneously: it seals the joint, accommodates expansion and contraction through its flexible material, and eliminates the need for separate venting mechanisms. The single component design provides sealing, flexibility, and contamination prevention without requiring additional specialized parts.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If external seals and vents are used on the boot assembly, then lubricant leakage can be managed, but contamination from dirt and water increases

Engineering Contradiction:

ImprovecontaminationVSAvoidjoint life

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent eliminates vent holes from the boot assembly, removing the opening that would allow contaminants to enter the joint. By taking out the vent feature entirely and relying on the integrated sealed design, the system prevents contamination while still managing lubricant pressure through the flexibility of the boot material itself.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The boot is constructed from flexible material that can expand and contract to accommodate lubricant pressure changes without requiring rigid vent holes or seals. This flexible shell design maintains sealing integrity while accommodating volume changes, preventing both lubricant leakage and contaminant infiltration.

Inventive Principle:

Principle #30Flexible shells and thin films

3Productivity

If the boot is crimped onto the mounting can separately, then assembly is possible, but manufacturing time and labor increase

Engineering Contradiction:

Improvemanufacturing timeVSAvoidassembly process

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The boot is pre-molded directly onto the mounting can in a single manufacturing step, creating a permanently attached integrated assembly. This preliminary action of bonding the boot to the mounting can during the molding process eliminates the need for separate crimping or attachment operations, reducing both manufacturing time and assembly complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The manufacturing process merges the boot formation and mounting can attachment into a single molding operation. Instead of producing separate components that require assembly, the integrated design allows both elements to be created together, simplifying the manufacturing process and reducing labor requirements.

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration reduces manufacturing time, enhances joint resilience, and prevents contamination by eliminating the need for external seals and vents, thereby extending the life of the constant velocity joint.

Implementation Method 1

a flexible boot member attached to an inner surface of at least two of the cylindrical body, the transition portion and the mounting portion at a coupling region

Methodology Applied

Scientific EffectOvermolding:

Data Source

PatentEP2758685B1External rolling diaphragm overmoulded high speed constant velocity joint boot

Publication Date: 2020.09.16 GKN DRIVELINE NORTH AMERICA INC

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AI summary

A constant velocity joint boot assembly includes a boot-can having an axially extending main cylindrical body, a radially extending transition portion, an axially extending and generally cylindrical mounting portion. The radially extending transition portion intersects the axially extending main cylindrical body and the generally cylindrical mounting portion. A flexible boot member may be attached to an inner surface of at least two of the cylindrical body, the transition portion and the mounting portion at a coupling region.