Rack Housing Inclination Structure for Warped Steering Rack Bars
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Solution Overview
Problem
The existing steering device is prone to damage due to excessive stress on the inner periphery of the rack housing when the rack bar warps, causing contact with the tubular section's corner, which leads to potential locking and reduced durability.
Innovation Solution
Incorporating a first inclination section at the axial end of the tubular section, inclined outwardly in the radial direction, which contacts the rack bar later than the tubular section during warping, distributing stress to inner peripheral surfaces and reducing the likelihood of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the rack bar is contained in a tubular rack housing without inclination sections, then the structure is simple, but the corner of the tubular section suffers excessive stress and may be damaged when the rack bar warps
Solution Approach 1:
The inner periphery of the axial end of the tubular section is segmented into multiple sections: a tubular section and at least two inclination sections. This segmentation distributes the contact points and stress distribution, preventing excessive stress concentration at a single corner location.
Solution Approach 2:
The inclination sections extend the contact surface from a single corner point into a multi-dimensional inclined surface structure. This dimensional transformation allows the rack bar to contact the inclination sections at different positions and angles, distributing the warping stress across multiple spatial locations rather than concentrating it at one corner.
2Stability of the object's composition
If the rack bar contacts the corner of the tubular section during warping, then the structure maintains compactness, but excessive stress is exerted on the corner causing potential damage
Solution Approach 1:
The inclination sections are designed to contact the rack bar before the warping force can concentrate on the corner of the tubular section. This pre-contact arrangement cushions the impact and distributes the stress gradually, preventing excessive force from reaching the vulnerable corner area.
Solution Approach 2:
Different sections of the inner periphery are given different geometric properties: the tubular section maintains a standard cylindrical form, while the inclination sections are shaped with specific inclination angles to gradually guide and distribute the warping stress. This local differentiation optimizes stress distribution while maintaining overall structural compactness.
3Reliability
If the inner periphery of the axial end is designed with inclination sections, then stress is distributed and damage is suppressed, but the manufacturing complexity increases
Solution Approach 1:
The inclination sections are defined by specific geometric parameters (inclination angles, axial positions, radial dimensions) that can be directly specified in CAD models and manufacturing drawings. By controlling these parameters, the complex geometry can be systematically designed and manufactured using conventional machining or forming processes.
Data Source
AI summary
A steering device includes: a steering shaft structured to receive rotational force; a rack bar in engagement with the steering shaft; and a rack housing that is made of a metal and contains the rack bar such that the rack bar is movable. The rack housing includes a tubular section extending in a movable direction of the rack bar, and includes a first inclination section disposed in an axial end of the tubular section and inclined to go away from the rack bar outwardly in a radial direction with respect to the rack bar. The tubular section is structured to contact with the rack bar in response to warping of the rack bar due to input from outside. The first inclination section is structured to contact with the rack bar later than the tubular section in response to warping of the rack bar due to input from outside.