Steering Shaft Stopper Geometry for Low-Stress Rotation Limiting

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In steer-by-wire systems, the existing mechanical structures for restricting the rotation range of a steering shaft are prone to stress concentration and potential damage due to head-on collisions between the rotation stopper and fixed stopper, which can reduce the rotation range and reliability.

Innovation Solution

A vehicle steering apparatus with a shaft member, a moving portion, a support member, and a stop portion, where the moving portion's first abutting surface is inclined relative to the axial direction to face the shaft support portion, and the stop portion's first abutted surface is also inclined to absorb impact, reducing stress concentration and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the circumferential width of the rotation stopper and fixed stopper is increased to reduce stress concentration, then the reliability is improved, but the rotation range of the shaft member is reduced

Engineering Contradiction:

ImprovereliabilityVSAvoidrotation range

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent transitions from a planar stopper design to a three-dimensional inclined surface design. The inclined surface extends in the axial direction of the rotor, creating a wedge-shaped contact geometry that distributes stress along the incline rather than concentrating it at a single point, thereby maintaining reliability without reducing rotation range

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the rotation stopper and fixed stopper abut each other on a plane parallel to the radial and axial directions, then the rotation range is restricted reliably, but stress concentrates on the proximal end of each stopper

Engineering Contradiction:

Improverotation range restrictionVSAvoidstress concentration

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent replaces the planar abutting surface with an inclined surface that creates a wedge-shaped contact geometry. This curved/angled surface distributes the impact force along the incline rather than concentrating it at the proximal end, reducing stress concentration while maintaining effective rotation range restriction

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The inclined surface design inherently provides stress distribution before the full impact occurs. The wedge geometry gradually distributes the stopping force along the incline, cushioning the impact before it reaches the proximal end of the stopper, thereby preventing stress concentration

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11332182B2Vehicle steering apparatus

Publication Date: 2022.05.17 JTEKT CORP

AI summary

A vehicle steering apparatus includes a shaft member, a moving portion, a support member, and a stop portion. The moving portion includes a first abutting surface that faces the stop portion in a circumferential direction of the shaft member. The first abutting surface is inclined with respect to an axial direction of the shaft member to face a shaft support portion side when the moving portion is viewed in a radial direction of the shaft member. The stop portion includes a first abutted surface that abuts the first abutting surface.