Integrated Guide Bushing in Steering Housing Cover
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Solution Overview
Problem
Existing electric power steering systems are complex to assemble and prone to wear and failure due to intricate suspension mechanisms in the guide bushing, which complicates the radial guidance of axially displaceable components.
Innovation Solution
The integration of guide bushings within a housing cover that seals axially and is cast during assembly, with a preferred embodiment of a one-piece core insert, provides a simplified assembly process and includes features like adjustable cross-sectional profiles and materials like polyamide for reduced wear, ensuring the guide bushing can accommodate bending and misalignment without jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex suspension mechanism is used for the guide bushing, then the radial guidance of the toothed rack is improved, but the assembly complexity increases
Solution Approach 1:
The guide bushing is integrated directly into the housing cover as a single component, eliminating the need for separate suspension mechanisms and multiple assembly steps. The housing cover itself serves as the mounting structure, combining the support function with the sealing function.
Solution Approach 2:
The guide bushing is extracted as a separate insert component that can be pre-manufactured with precise tolerances and then inserted into the housing cover, simplifying the overall assembly process while maintaining guidance reliability.
2Manufacturing precision
If a fixed guide bushing design is used, then the manufacturing precision is improved, but the adaptability to rack deflection decreases
Solution Approach 1:
The guide bushing is designed with a thin-walled structure that provides flexibility to accommodate rack deflection while maintaining precise guiding surfaces. The wall thickness is optimized to allow slight deformation under load without compromising the guide function.
Solution Approach 2:
The guide bushing transitions from a completely rigid fixed design to a dynamically adaptable structure that can flex slightly to follow rack deflection, while maintaining manufacturing precision through controlled flexibility.
3Strength
If the guide bushing wall thickness is increased, then the structural strength is improved, but the rack jamming risk increases
Solution Approach 1:
The wall thickness parameter is optimized to a specific range that balances structural strength with flexibility. The thickness is sufficient to provide strength but thin enough to allow the guide bushing to flex with rack deflection, preventing jamming.
Data Source
Figure 1
AI summary
The invention relates to an electric power steering system, in particular a servo steering system (1) for a vehicle, comprising a steering transmission housing (2) and a housing cover (3) that axially seals the steering transmission housing (2), said cover being penetrated by an axially displaceably component (4) of the steering transmission (5). The aim of the invention is to provide an electric power steering system that is easy to assemble and is not susceptible to wear. To achieve this, a first guide bush (7) for the axially displaceable component (4) is integrated into an axially outer region (6) of said cover (3).