Eccentric Rack Housing Layout for Steering Load Support
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Solution Overview
Problem
The existing vehicle steering systems face issues with the rack bar bending due to reverse input loads, leading to a sense of being stuck, component wear, and damage, as well as complicating the assembly process due to load concentration and increased bending moments.
Innovation Solution
A rack housing design with a body and cover where the central axis of the insertion hole is eccentric to the central axis of the receiving hole, incorporating a rack bushing to absorb bending moments and distribute loads effectively, thereby reducing the risk of component damage and maintaining ease of assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the assembly gap between the rack bushing and the rack bar is reduced to increase load support capability, then the rack bar can better support reverse input loads, but the ease of assembly deteriorates
Solution Approach 1:
The patent applies asymmetry by making the insertion hole's central axis eccentric relative to the receiving hole's central axis. This asymmetric positioning allows the rack bushing to be pre-compressed in a specific direction, creating initial contact pressure that enhances load support capability while preserving sufficient assembly gap for easy installation. The asymmetric design enables the bushing to accommodate bending moments effectively without requiring a reduced assembly gap.
2Strength
If the rack bushing inner diameter is reduced to support higher loads, then the load support capability improves, but the ease of assembly deteriorates
Solution Approach 1:
The patent applies local quality by creating non-uniform contact pressure distribution through the eccentric insertion hole design. The rack bushing is compressed more heavily in the direction of eccentricity, providing enhanced load support capability in the critical loading direction while maintaining larger clearance in other directions. This localized quality enhancement allows the bushing to support higher loads without requiring a uniform reduction in inner diameter, thereby preserving ease of assembly.
3Ease of operation
If the rack bar is designed to accommodate larger bending moments, then the steering performance improves, but the component wear and damage increases
Solution Approach 1:
The patent applies beforehand cushioning by pre-compressing the rack bushing through the eccentric insertion hole design. This pre-compression creates an initial cushioning effect that absorbs bending moments before they are transmitted to the rack bar and other components. The pre-compressed bushing acts as a shock absorber, reducing component wear and damage while allowing the steering system to handle larger bending moments and improve steering performance.
Data Source
AI summary
According to the present exemplary embodiments, a rack housing having a body, a rack bar and a cover is disclosed and configured to mitigate a sense of being stuck during steering, reducing component wear and damage due to load concentration, and prevent deterioration of case of assembly by supporting the reverse input load that causes the rack bar to bend.