Power Steering Housing Gap Structure for Thrust Load Noise
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Solution Overview
Problem
Conventional housing structures for power steering apparatuses experience abnormal sounds due to thrust loads causing displacement and contact issues between tubular portions, leading to stick-slip noises.
Innovation Solution
Incorporating first and second gaps between tubular end and opposite surfaces to prevent contact when thrust loads act, ensuring the fitting inner and outer tubular portions separate and re-align without causing abnormal sounds, and positioning surfaces to maintain alignment with bolt fastening surfaces for structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fitting area between the fitting inner tubular portion and the fitting outer tubular portion is located away from bolt fastening portions, then the assist shaft can be precisely centered, but the tubular portions are likely to be displaced in the axial direction under thrust load
Solution Approach 1:
The patent divides the fitting structure into three distinct segments: the fitting inner tubular portion, the fitting outer tubular portion, and the intermediate pressing portion. This segmentation allows each part to perform its specific function - the fitting portions maintain centering precision while the pressing portion provides axial positioning stability under thrust loads.
Solution Approach 2:
The pressing portion acts as an intermediary element between the fitting inner tubular portion and the fitting outer tubular portion. It mediates the connection by providing pressing force to maintain axial positioning, allowing the fitting portions to remain away from bolt fastening portions for precise centering while preventing axial displacement through the intermediate pressing action.
2Strength
If the outer tubular end surface and the outer tubular opposite surface are in contact, then structural support is provided, but abnormal stick-slip sounds occur under thrust load
Solution Approach 1:
The pressing portion serves as an intermediary that provides continuous pressing force between the fitting inner tubular portion and the fitting outer tubular portion. This intermediary action prevents direct contact between the outer tubular end surface and the outer tubular opposite surface, thereby eliminating the stick-slip phenomenon and abnormal sounds while still providing necessary structural support through the pressing mechanism.
Solution Approach 2:
The pressing portion provides beforehand cushioning by continuously applying pressing force to prevent direct contact between the outer tubular surfaces. This prior cushioning action ensures that even under thrust loads, the surfaces do not come into direct contact, preventing the generation of abnormal stick-slip sounds before they can occur.
3Reliability
If the O ring is interposed between the fitting inner tubular portion and the fitting outer tubular portion, then sealing is achieved, but the O ring deforms under thrust load causing displacement
Solution Approach 1:
The patent segments the sealing function from the positioning function. The O ring is dedicated to sealing between the fitting inner tubular portion and the fitting outer tubular portion, while the pressing portion handles the positioning function by providing pressing force. This segmentation prevents the O ring from bearing radial displacement forces, maintaining both sealing reliability and radial position stability.
Solution Approach 2:
The pressing portion acts as an intermediary that bears the radial positioning function, protecting the O ring from displacement forces. By providing continuous pressing force, it prevents the O ring from being deformed by thrust loads, thereby maintaining both the sealing reliability and the radial position stability of the tubular portions.
Data Source
AI summary
A housing structure includes: a first housing having a fitting inner tubular portion that has an inner tubular end surface and a first bolt fastening portion that has a first bolt aligning surface formed at a position away from the inner tubular end surface in the radial direction, the first housing supporting a first end of an assist shaft via a first bearing; and a second housing having a fitting outer tubular portion having an outer tubular end surface and a second bolt fastening portion that has a second bolt aligning surface that mates with the first bolt aligning surface, the second housing supporting a second end of the assist shaft via a second bearing. A first gap is provided between the inner tubular end surface and an inner tubular opposite surface, and a second gap is provided between the outer tubular end surface and an outer tubular opposite surface.