Steering Apparatus Collision Relaxation Member Design

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Solution Overview

Problem

Existing steering apparatuses face challenges in reducing the abutting speed of rack ends during power loss or control circuit failure, leading to potential damage and increased collision loads on the housing.

Innovation Solution

Incorporating a collision relaxation member with an elastic member and a shock absorbing member on the housing surface, where the elastic member absorbs initial collision loads and the shock absorbing member buckles to reduce the abutting speed of rack ends, thereby minimizing damage and collision loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If only an elastic member is used to absorb collision load, then the collision load is reduced, but the abutting speed of rack ends cannot be reduced in failure states

Engineering Contradiction:

Improvecollision loadVSAvoidabutting speed control in failure state

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The collision relaxation member is divided into two functional segments: an elastic member for absorbing collision loads and a shock absorbing member for reducing abutting speed. This segmentation allows each component to specialize in its function, with the elastic member handling normal collision forces and the shock absorbing member activating during failure states to limit rack end velocity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The shock absorbing member is pre-positioned inside the elastic member, ready to engage when the rack end abuts. This beforehand cushioning ensures that when failure occurs and the rack end gains excessive speed, the shock absorbing member is already in place to immediately buckle and reduce the abutting speed, preventing damage without requiring active control

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Force

If motor output control is used to reduce abutting speed, then collision load is reduced, but the method fails during power loss or control circuit failure

Engineering Contradiction:

Improvecollision loadVSAvoidfunctionality in failure state

Core Design Contradiction:

ForceVSAdaptability or versatility

Solution Approach 1:

The shock absorbing member operates autonomously based on mechanical conditions rather than electronic control. When the rack end abuts with excessive force, the shock absorbing member automatically buckles to reduce speed, providing self-service protection that functions independently of power supply or control circuit status

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The shock absorbing member acts as a mechanical intermediary between the rack end and the housing. Instead of relying on electronic control systems to mediate the interaction, this passive mechanical element directly intervenes to reduce abutting speed when failure occurs, bridging the gap left by failed electronic control

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a shock absorbing member buckles to reduce abutting speed, then damage to other parts is suppressed, but the device complexity increases

Engineering Contradiction:

Improvedamage to other partsVSAvoidstructure of collision relaxation member

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The shock absorbing member is nested inside the elastic member, with the shock absorbing member having a smaller outer diameter than the inner diameter of the elastic member. This nested arrangement protects the shock absorbing member during normal operation while allowing it to engage when needed, reducing overall complexity compared to having two separate external components

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The shock absorbing member utilizes buckling of a thin-walled tubular structure to absorb shock. This flexible shell approach allows the member to deform controllably under load, providing effective shock absorption with minimal material and simple geometry rather than requiring complex rigid 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

This configuration effectively reduces the abutting speed of rack ends and minimizes damage to other parts by absorbing collision loads, even in failure states, while maintaining reduced collision loads on the housing.

Implementation Method 1

an elastic member arranged in an outer side of the rack shaft in a radial direction and absorbing a collision load from the corresponding rack end

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a shock absorbing member provided in an inner peripheral side of the elastic member and buckling by the abutting of the rack end

Methodology Applied

Scientific EffectBuckling: Deformation

Data Source

PatentUS9156493B1Steering apparatus

Publication Date: 2015.10.13 ASTEMO LTD

AI summary

A steering apparatus includes a collision relaxation member provided on a surface of a housing, the surface being opposed to each rack end in a vehicle width direction. The collision relaxation member includes an elastic member arranged in an outer side of a rack shaft in a radial direction and absorbing a collision load from the corresponding rack end, and a shock absorbing member provided in an inner peripheral side of the elastic member and buckling by abutting of the rack end.