Steering Input Shaft Guide and Seal Assembly
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Solution Overview
Problem
Conventional electric power steering systems experience friction and noise due to the tight mounting of guide members on the casing and input shaft, leading to vibration transmission issues.
Innovation Solution
An integrated guide and sealing member assembly with radial clearances, where the guide member is independent of the housing and shaft, allowing specific geometry to manage radial forces and reduce friction and vibrations by distributing forces across both members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the guide member is tightly mounted on the casing and/or input shaft, then the guide member is securely positioned, but friction and noise increase and vibrations are transmitted
Solution Approach 1:
The guide member is divided into two independent parts: an outer guide member mounted on the casing and an inner guide member mounted on the input shaft. This segmentation allows each part to be positioned stably without requiring tight mounting between them, as the sealing member fills the gap between the two segmented parts, eliminating friction and vibration transmission while maintaining positioning stability.
Solution Approach 2:
The sealing member acts as an intermediary element between the outer and inner guide members. It fills the annular gap between these two guide members, providing both sealing and mechanical coupling functions. This intermediary allows the guide members to be independently mounted with clearances while maintaining overall system stability and eliminating direct contact friction.
2Object-generated harmful factors
If the guide member is made independent of the housing and shaft, then friction and vibrations are reduced, but the guide member cannot hold itself in position
Solution Approach 1:
The guide function is segmented between two independent guide members mounted on different components (casing and input shaft). Each guide member is independently positioned and stabilized by its mounting location, eliminating the need for one guide member to hold itself while reducing friction and vibration through the clearance between segmented parts.
Solution Approach 2:
The sealing member serves multiple functions simultaneously: it provides sealing between the guide members, acts as a mechanical intermediary to transfer radial forces, and maintains the positional relationship between the independently mounted outer and inner guide members. This multi-functionality allows independent mounting while ensuring stability.
3Device complexity
If a single guide member is used, then the structure is simple, but friction and noise are generated due to tight mounting
Solution Approach 1:
The single guide member structure is segmented into two independent guide members (outer and inner) mounted on different components. This segmentation increases structural complexity slightly but eliminates the tight mounting requirement, thereby reducing friction and noise while maintaining reasonable overall simplicity.
4Reliability
If the sealing member bears all radial force, then the sealing function is maintained, but permanent deformation occurs under high radial force
Solution Approach 1:
The force-bearing function is segmented between two independent guide members, creating a load path that distributes radial forces. The outer guide member on the casing and inner guide member on the input shaft share the radial load, preventing the sealing member from bearing all forces and avoiding permanent deformation while maintaining sealing reliability.
Solution Approach 2:
The sealing member acts as an intermediary in the force transmission path between the outer and inner guide members. It distributes radial forces across both guide members rather than concentrating all forces on itself, thereby maintaining sealing function while preventing permanent deformation through force distribution.
Data Source
Figure 1~2
AI summary
The assembly has an input shaft (2) rotatively mounted on a casing (1) and comprising an external part (20) to receive a steering column and an internal part (21) engaged in the casing across a circular opening (10) of the casing. A sealing member (3) is mounted to contact around the internal part and with the casing to assure sealing of the opening. An annular guiding member (4) i.e. ring, guides the input shaft inside the casing. The guiding member is integrally mounted to the sealing member and shaped for defining radial clearances with the casing and the input shaft, respectively. The guiding and sealing members are made from damping material i.e. elastic plastic material.