Steering Shaft Bearing Support Structure for Reverse Load Stability

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Solution Overview

Problem

Existing steering systems face challenges in meeting diverse customer demands due to limitations in configuration and component stability, particularly in handling reverse input loads and maintaining assembly ease.

Innovation Solution

A novel steering system incorporating a cylindrical support tube with a flange, a speed reducer, and a bearing support member that is press-fitted into a housing, featuring a unique bearing support member design with a coupling wall and inclined portions to manage axial loads and improve assembly, reducing dislodging risks and component count.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional bearing support member design is used, then the structure is simple, but the bearing support member may dislodge under reverse input loads and requires additional fastening components

Engineering Contradiction:

Improvebearing support member position stabilityVSAvoidbearing support member structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bearing support member employs an asymmetric structure where the inner circumferential wall extends longer in the mounting direction than in the opposite direction. This asymmetric design creates different engagement characteristics for axial loads in opposite directions, preventing dislodging under reverse input loads without requiring additional fastening components

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention addresses the bearing support member stability problem by transitioning from a simple cylindrical design to one with extended walls in specific axial directions. This dimensional modification adds engagement surfaces that interact with the housing, creating mechanical interlocking that prevents dislodging while maintaining structural simplicity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If multiple fastening components are used to secure the bearing support member, then position stability is improved, but assembly complexity and production costs increase

Engineering Contradiction:

Improvebearing support member position stabilityVSAvoidassembly ease and production cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The bearing support member's asymmetric wall structure serves its own positioning and securing function through the differential extension lengths. The longer inner circumferential wall in the mounting direction provides engagement that automatically secures the member during assembly, eliminating the need for separate fastening components and simplifying both manufacturing and assembly processes

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250091638A1Steering device

Publication Date: 2025.03.20 JTEKT CORP

AI summary

A steering system has a support tube that supports a steering shaft, and a housing that has a cylindrical portion housing a speed reducer. A bearing support member is fitted to an inner circumferential face of the cylindrical portion. A bearing is disposed between an outer circumferential face of the steering shaft and an inner circumferential face of the bearing support member. The bearing support member has an inner circumferential wall that fits to an outer circumferential face of the bearing, an outer circumferential wall that fits to the inner circumferential face of the cylindrical portion, and a coupling wall that couples the inner circumferential wall and the outer circumferential wall in a radial direction. The inner circumferential wall extends from the coupling wall in a same direction as a mounting direction, and the outer circumferential wall extends in an opposite direction from the mounting direction.