Bearing Bushing Preload Structure for Low-Torque Worm Gear Assembly
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Solution Overview
Problem
Current automobile steering systems face challenges with complex housing designs, poor universality, excessive friction torque, and noise issues due to manufacturing tolerances and installation errors, particularly in column-drive electric power steering systems, where prior solutions are cumbersome and costly.
Innovation Solution
A bearing bushing with a spring piece and buffer members, including a C-shaped clip-shaped part and elastic pads, is used to provide a preload structure that adjusts the worm gear and worm assembly, allowing for simpler assembly and reduced friction torque by changing the end cover and bearing mount support module, rather than redesigning the entire housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different housings are designed according to different whole vehicle designs, then the housing can adapt to different vehicle interfaces, but the housing structure becomes complicated and universality deteriorates
Solution Approach 1:
The housing is divided into a fixed base housing and a replaceable end cover assembly. The end cover assembly includes the end cover, bearing support module, and preload structure, which can be replaced as a unit to adapt to different vehicle interfaces without redesigning the entire housing. This segmentation enables different configurations for different vehicles while keeping the main housing structure standardized and simple.
Solution Approach 2:
The base housing is designed with universal mounting features and standardized interfaces that can accommodate multiple end cover assemblies. The standardized bearing support module with fixed mounting positions allows the same housing to support different preload structures and bearing configurations, achieving multi-functionality and broad adaptability across different vehicle platforms.
2Ease of manufacture
If manufacturing tolerances and installation errors are not controlled, then production cost is reduced, but excessive friction torque and noise occur
Solution Approach 1:
The preload force is adjusted by changing the spring piece parameters (wire diameter, coil diameter, number of active coils, material properties) rather than relying on precise mechanical clearances. This allows tolerance compensation through elastic deformation, reducing the impact of manufacturing and installation errors on friction torque and noise while maintaining easier manufacturing processes.
Solution Approach 2:
The spring piece acts as an intermediary element between the bearing support module and the housing, providing elastic preload that compensates for tolerance variations. This intermediary mechanism transforms rigid tolerance requirements into flexible elastic deformation, reducing harmful effects of manufacturing errors on friction and noise.
3Reliability
If bracket bearing solution or separate compression spring is used, then preload can be applied, but tolerance accumulation increases and robustness deteriorates
Solution Approach 1:
The bearing support module integrates the bearing, spring piece, and mounting structure into a single pre-assembled unit with fixed relative positions. This merging eliminates tolerance accumulation between separate components (bracket, bearing, spring) and improves robustness by reducing the number of interfaces and assembly steps while maintaining reliable preload application.
4Manufacturing precision
If high processing accuracy requirements are imposed on parts, then assembly precision is improved, but manufacturing cost increases and quality consistency deteriorates
Solution Approach 1:
The spring piece provides self-adjusting preload that automatically compensates for assembly tolerances and wear. The elastic deformation of the spring piece absorbs dimensional variations, eliminating the need for high-precision machining of individual components while maintaining consistent assembly quality and reducing manufacturing costs.
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 solution simplifies the assembly process, reduces production costs, and enhances the robustness of the preload design, minimizing friction torque and noise in the worm gear and worm under various conditions, while maintaining consistent quality and reducing the need for high-precision part processing.
Implementation Method 1
the spring piece comprises an extending part and a fixed part, the extending part obliquely extends downward from two opposite sides of the fixed part
Data Source
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AI summary
A bearing bushing, comprising: a bushing body and a buffer member fixed therein. The buffer member comprising a spring piece. The spring piece is provided on the top of the bushing body, and comprises an extending part and a fixed part. The extending part obliquely extends downward from two opposite sides of the fixed part. The bearing bushing provides a special preload force for the deformation of the fixed part by means of the extending part of the spring piece so as to enhance the robustness of the preload design, reduce the friction torque, and reduce the engaging noise of the worm gear and the worm in different working situations. Also disclosed are a preload structure, a housing of a transmission mechanism, and an assembling structure of a worm gear and a worm.