Self-Sealing Yoke Assembly for Steering Apparatus

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Solution Overview

Problem

Modern automotive steering assemblies face corrosion issues due to water and contaminants entering through the yoke plug threads, leading to axial lash, noise, vibration, and potential loss of power steering function, which existing designs attempt to mitigate with additional seal members increasing costs.

Innovation Solution

A self-sealing yoke assembly featuring a cylindrical sleeve with a tapered seal surface and a retainer member with a compliant annular seal, which engages the sleeve to create a sealed interface without additional components, using ultrasonic welding for a secure connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate seal member is added between the rack and pinion housing and the yoke plug, then the sealing performance is improved, but the manufacturing cost and component complexity increase

Engineering Contradiction:

Improvesealing performanceVSAvoidcomponent quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged into the retainer member by incorporating a compliant flange directly into its structure. This eliminates the need for a separate seal member while maintaining the sealing function, thereby reducing component quantity and manufacturing cost while preserving reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The retainer member is designed to serve multiple functions: it retains the yoke plug in position and simultaneously provides sealing through its compliant flange. This multi-functionality reduces the total number of components needed in the assembly

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a separate seal member is added between the rack and pinion housing and the yoke plug, then the sealing performance is improved, but the production cost increases

Engineering Contradiction:

Improvesealing performanceVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The compliant flange on the retainer member self-provides the sealing function that would otherwise require a separate seal member. The flange's elasticity allows it to conform to the seal surface, creating an effective seal without additional components or assembly steps

Inventive Principle:

Principle #25Self-service

3Device complexity

If the yoke plug threads are used without additional sealing, then the device complexity is reduced, but water and contaminants can penetrate causing corrosion

Engineering Contradiction:

Improvecomponent quantityVSAvoidcorrosion resistance

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The compliant flange acts as an intermediary sealing element between the retainer member and the seal surface. It creates a barrier that prevents water and contaminants from penetrating through the yoke plug threads, protecting internal components from corrosion while maintaining simple device architecture

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The compliant flange utilizes elastic deformation to create an effective seal. Its flexibility allows it to conform to the seal surface and maintain sealing pressure, preventing contaminant ingress without requiring complex sealing mechanisms

Inventive Principle:

Principle #30Flexible shells and thin films

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 solution effectively seals the steering system components from water and contaminants, reducing costs and preventing corrosion-related issues like axial lash and power steering fluid loss, while maintaining engagement between the rack and pinion teeth.

Implementation Method 1

a compression spring between the yoke member and the yoke plug to apply a force to the rack through the yoke member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

A retainer member holds the yoke plug in position and has a compliant flange, or annular seal member, that has an inner seal surface having a slight outwardly extending taper to provide a self-sealing interface with the seal surface of the cylindrical sleeve

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

using ultrasonic welding for a secure connection

Methodology Applied

Scientific EffectUltrasonic welding: Ultrasonic Vibration

Data Source

PatentUS7458291B2Self-sealing yoke assembly for a steering apparatus

Publication Date: 2008.12.02 FORD GLOBAL TECH LLC

AI summary

A rack and pinion steering system including a rack slidably supported within a housing that engages in a pinion gear wherein the housing includes a cylindrical sleeve having an outer seal surface with a slight medial taper at one end thereof. A yoke assembly, which is received by the cylindrical sleeve, operates to guide the rack and maintain engagement of the rack and pinion during operation of the steering system and includes a yoke member engaging the rack. A retainer member holds a yoke plug, used in the yoke assembly, in position and has a compliant annular seal member having an inner sealing surface that has a complementary slight outward extending taper to provide a self-sealing interface with the medial taper of the outer seal surface of the cylindrical sleeve to protect the internal components of the steering system from water and other contaminants.