Steering Rack Assembly Teeth for Stable Pinion Engagement
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Solution Overview
Problem
The existing electric power steering systems face difficulties in maintaining the connection between the pinion shaft and the rack during initial assembly and subsequent repair operations, leading to potential misalignment and the need for recalibration of sensor systems.
Innovation Solution
The electric power steering system incorporates a rack with an assembly portion featuring second teeth of lower height than the standard teeth, ensuring a defined connection during initial assembly and preventing disengagement during repairs, while allowing sufficient installation space for easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rack has a toothless recess assembly portion to facilitate initial assembly of the pinion shaft, then the ease of assembly is improved, but the reliability of the connection between pinion shaft and rack deteriorates during repair operations
Solution Approach 1:
The rack features two distinct tooth configurations: standard-height teeth in the working portion for normal operation, and reduced-height teeth in the assembly portion for facilitated initial assembly. This local differentiation allows the assembly portion to serve as a guide during initial assembly while the working portion maintains full functional capability, resolving the contradiction between ease of assembly and connection reliability.
Solution Approach 2:
The reduced-height teeth in the assembly portion act as preliminary guiding elements that facilitate the initial engagement of the pinion shaft with the rack. Once assembly is complete, the pinion shaft operates normally with the full row of teeth. The preliminary action of the reduced-height teeth enables easy assembly without compromising the reliability of the final connection during repair operations.
2Reliability
If the rack has uniform teeth throughout for consistent meshing, then the reliability of connection is improved, but the ease of initial assembly deteriorates
Solution Approach 1:
Instead of uniform teeth throughout, the rack implements local quality variation with reduced-height teeth specifically in the assembly portion. This allows the majority of the rack to maintain standard teeth for reliable operation, while the localized modification at the assembly portion provides the necessary facilitation for initial assembly without compromising overall connection stability.
3Ease of repair
If the pinion shaft can move freely during repair work, then the ease of repair is improved, but the positioning precision of the pinion shaft deteriorates
Solution Approach 1:
The reduced-height teeth in the assembly portion provide localized guidance that maintains pinion shaft positioning during repair operations. When the pinion shaft shifts during repair work, these teeth continue to provide a defined reference position, ensuring that the pinion shaft returns to the correct alignment after repair, thus maintaining positioning precision while allowing repair accessibility.
Data Source
AI summary
The disclosure relates to an electric power steering system having a rack for steering wheels of a vehicle and having a pinion shaft. The pinion shaft meshes with a row of teeth of the rack in an assembled state. The rack has an assembly portion for an initial assembly of the pinion shaft, with one end of the row of teeth transitioning into the assembly portion. On the one hand, to facilitate initial assembly for establishing a connection between the pinion shaft and the row of teeth of the rack and, on the other hand, to prevent the connection between the pinion shaft and the row of teeth of the rack from breaking during repair measures carried out after the initial assembly, the electric power steering system is arranged such that first teeth of the row of teeth each have a first tooth height and the assembly portion has second teeth for interacting with the pinion shaft, the second teeth each having a second tooth height that is less than the first tooth height.