Pivot-Pendulum Bearing Assembly for Zero-Play Power Steering
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Solution Overview
Problem
Electromechanical power steering systems face issues with noise and play due to asymmetrical loads on worm shaft bearings, leading to increased wear and acoustic problems, as existing solutions fail to effectively compensate for tolerances and environmental influences without excessive pretensioning.
Innovation Solution
An electromechanical power steering system with a bearing assembly featuring a roller bearing, an eccentric cam, and a pretensioning installation that adjusts play between the helical gear and shaft, providing a two-point asymmetrical support to reduce noise and wear, using a lever arm and spring element for resilient pretensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mounting is displaceably mounted to allow bearing race movement toward the toothing, then play in the toothing is reduced, but the mounting becomes complex and requires additional pretensioning elements
Solution Approach 1:
The patent combines the bearing support function and mounting function into a single integrated component. The bearing support is directly displaceably mounted in the gearbox housing, eliminating the need for separate mounting structures and pretensioning elements. This integration reduces device complexity while maintaining the ability to adjust and eliminate toothing play through the bearing support's displacement capability.
2Manufacturing precision
If excessive pretensioning force is applied to the toothing, then play is eliminated, but breakaway torque and wear become excessive
Solution Approach 1:
The patent implements a dynamic pretensioning system where the bearing support can displace elastically in response to load variations. This dynamic capability allows the system to maintain optimal pretensioning force that eliminates toothing play without applying excessive static force that would cause high breakaway torque and wear. The elastic displacement of the bearing support automatically adjusts the pretensioning force according to actual operating conditions.
3Device complexity
If the bearing is fixed in the housing, then the structure is simple, but play increases over time due to wear and environmental influences
Solution Approach 1:
The bearing support is designed with elastic displacement capability, transforming it from a static fixed structure to a dynamic adaptive structure. This allows the bearing support to automatically compensate for wear and environmental influences by displacing toward the toothing as needed, maintaining zero play over time without requiring complex adjustment mechanisms or multiple components.
4Productivity
If asymmetrical loads are applied to the worm shaft bearings, then the gearbox functions, but wear increases and service life decreases
Solution Approach 1:
The patent employs an asymmetrical two-point support system where the bearing support contacts the gearbox housing at two differently oriented contact faces. This asymmetrical configuration is specifically designed to counterbalance the asymmetrical loads generated by the worm gear toothing angles, distributing the loads more evenly across the bearing and reducing wear, thereby extending service life while maintaining proper gearbox function.
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
The solution effectively reduces noise and play in the gearbox, ensuring long-term performance by maintaining zero play under all load conditions and minimizing wear, thus enhancing the service life of the components.
Implementation Method 1
a spring that engages on the mounting and presses the worm shaft in an elastic manner without play against the toothing of the worm gear
Implementation Method 2
a bearing assembly having a roller bearing so as to be rotatable about a rotation axis, comprising a pretensioning installation which for adjusting the play in the engagement between the helical gear and the shaft resiliently pretensions a movable bearing element of the bearing assembly in relation to the gearbox housing
Data Source
AI summary
An electromechanical power steering system may include an electric servomotor that has a motor shaft and drives a shaft that meshes with a helical gear. The shaft is disposed in a gearbox housing and rotatably mounted in a bearing assembly. A pretensioning installation, for adjusting engagement between the helical gear and the shaft, resiliently pretensions a movable bearing element of the bearing assembly relative to the gearbox housing. The gearbox housing has a housing portion having first and second contact faces, the normals of which do not intersect. The bearing assembly has a bearing support that forms the movable bearing element and has a lever arm having a free end that extends from a main body of the bearing support and on the gearbox housing lies against the second contact face. The main body has an eccentric cam that on the housing lies against the first contact face.