Pivotable Worm Shaft Bearing for Low-Wear Power Steering Gearing
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Solution Overview
Problem
Existing electromechanical power steering systems experience rapid wear and increased vibration noises due to excessive loading of the coupling between the engine shaft and worm shaft, leading to increased toothed flank play.
Innovation Solution
The system employs a pivotable bearing arrangement with a roller bearing and cylindrical pins to support the worm shaft, allowing it to pivot about a pivot axis perpendicular to the rotation axis, reducing the axial offset and loading on the coupling, and using a coupling with concentric bearing seats and a helical spring for axial compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the worm shaft is supported by a gimbal-mounted bearing ring with a pivot axis extending perpendicularly to the rotation axis, then the coupling is more heavily loaded, but the structure is simpler, which leads to rapid wear and increased toothed flank play over time
Solution Approach 1:
The patent applies the dynamics principle by making the bearing pivotable rather than fixed. The bearing is designed to pivot about a pivot axis that is perpendicular to the rotation axis and extends through the coupling, allowing the bearing to dynamically adjust its position and compensate for misalignments. This dynamic capability reduces the loading on the coupling while maintaining structural simplicity, thereby resolving the contradiction between device complexity and reliability.
2Strength
If the coupling is designed to compensate for axial offset, then the loading on the coupling is reduced, but additional components are required, which increases device complexity
Solution Approach 1:
The patent merges the bearing support function with the coupling compensation function into a single integrated bearing assembly. The bearing is designed to perform both the support function and the pivotable compensation for axial offsets and misalignments. By combining these functions, the patent reduces the loading on the coupling while avoiding the need for separate compensation components, thus resolving the contradiction between strength and device complexity.
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 design reduces the loading on the coupling, enhancing its lifespan and reducing vibration noises, while also allowing for alignment errors and axial offsets to be compensated, thus improving the overall performance and reliability of the power steering system.
Implementation Method 1
The bearing comprises a roller bearing which supports the shaft so as to be able to pivot about a pivot axis
Implementation Method 2
using a coupling with concentric bearing seats and a helical spring for axial compensation
Data Source
AI summary
An electromechanical power steering system having an electric servo motor having a motor shaft. The electric servo motor drives a shaft which meshes with a helical wheel. The shaft is rotatably supported in a gear mechanism housing. The motor shaft is coupled to the shaft in a rotationally secure manner by a coupling which compensates for an axial offset. The shaft at the end thereof close to the motor is supported in a bearing in the gear mechanism housing so as to be able to be rotated about a rotation axis and is pivotably supported about a pivot axis which is perpendicular to the rotation axis in such a manner that the pivot axis is arranged in the region of the coupling.