Steering Cover Annular Lips Friction Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In rack and pinion type steering systems, increasing the length of the torsion bar to enhance steering torque detection accuracy can lead to buckling of the dust cover due to frictional resistance during attachment, compromising waterproof integrity.
Innovation Solution
The design incorporates a cover member with multiple annular lips on its inner surface that extend circumferentially and are elastically contacted with the input shaft, reducing frictional resistance and preventing buckling, while maintaining waterproof properties through a non-water stagnating shape and strategic lip placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the length of the cylindrical portion of the dust cover is increased to cover a longer torsion bar, then the waterproof property is improved, but the cylindrical portion is likely to buckle due to frictional resistance during attachment
Solution Approach 1:
The inner peripheral surface of the cylindrical portion is segmented into multiple circumferential regions, with annular lips provided in alternate regions. This segmentation allows the dust cover to maintain waterproofing in regions with lips while reducing frictional resistance and preventing buckling in regions without lips, thus resolving the contradiction between waterproof property and attachment ease.
2Measurement precision
If the length of the torsion bar is increased to enhance steering torque detection accuracy, then the measurement precision is improved, but the distance between the through hole and upper opening increases, requiring a longer cylindrical portion that is more prone to buckling
Solution Approach 1:
By segmenting the inner peripheral surface and providing annular lips only in alternate circumferential regions, the dust cover can achieve the necessary waterproofing for longer torsion bars without requiring a uniformly long cylindrical portion. This reduces the overall complexity and buckling risk while enabling longer torsion bar implementation for improved measurement precision.
3Ease of operation
If the interference of the dust cover with the input shaft is reduced to decrease frictional resistance, then the attachment ease is improved, but the waterproof property cannot be obtained sufficiently
Solution Approach 1:
The segmented configuration with annular lips in alternate regions provides a balanced solution: regions with annular lips maintain waterproof integrity by increasing interference, while regions without lips reduce frictional resistance and facilitate attachment. This segmentation allows both waterproof property and attachment ease to be satisfied simultaneously.
Solution Approach 2:
Different regions of the inner peripheral surface have different interference characteristics - regions with annular lips have higher interference for waterproofing, while regions without lips have lower interference for easy attachment. This local differentiation of quality resolves the contradiction between waterproof property and attachment ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for easier attachment of the cover member, reduces manufacturing costs, and ensures improved waterproofing by minimizing water entry into the steering system components.
Implementation Method 1
frictional resistance generated between the inner peripheral surface of the dust cover and the outer peripheral surface of the input shaft
Implementation Method 2
ridges of the annular lips are brought into elastic contact with the outer peripheral surface of the input shaft
Data Source
AI summary
A steering system includes a pinion shaft that meshes with a rack shaft, an input shaft, a torsion bar that couples the input shaft and the pinion shaft together, a fixing pin that fixes the torsion bar to the input shaft, a housing having a first housing portion that houses a part of the input shaft, and a cover member having a cylindrical portion externally fitted to the input shaft protruding from the first housing portion, and a disc portion that covers an end face of the first housing portion. A through hole where the fixing pin is inserted is formed in the input shaft. On the cylindrical portion of the cover member, a plurality of annular lips are provided, except for a portion that faces each of openings of the through hole, on one side and the other side in an axial direction with respect to the portion.