Eccentric Sleeve Steering Gear Assembly for Mesh Delashing
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Solution Overview
Problem
Current integral gear systems in electric power steering systems face complexity in design and manufacturing due to tapered teeth, which lead to excessive gear lash, noise, and rattle issues related to tooth wear.
Innovation Solution
The introduction of an eccentric sleeve assembly with separate upper and lower sleeve segments that delash the sector gear mesh, allowing for a simpler spur tooth design and independent handling of radial and axial loads, reducing manufacturing complexity and noise issues through the use of needle bearings and a compensation mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tapered teeth are used in the gear system, then the gear mesh can be delashed and loads can be transmitted radially and axially, but the design complexity and manufacturing complexity increase significantly
Solution Approach 1:
The gear system is segmented into distinct functional components: the sector gear with spur teeth handles radial load transmission, while the separate eccentric sleeve with tapered teeth handles axial load and gear mesh delashing. This segmentation allows each component to be optimized for its specific function, reducing overall design complexity while maintaining the delashing capability.
2Force
If tapered teeth are used in the gear system, then loads can be transmitted radially and axially, but the manufacturing complexity increases and design options are limited
Solution Approach 1:
The load transmission function is segmented between two component types: spur teeth for radial loads (simpler to manufacture) and tapered teeth on the eccentric sleeve for axial loads. This allows manufacturers to choose from multiple design options for each segment, reducing overall manufacturing complexity while maintaining full load transmission capability.
Solution Approach 2:
The eccentric sleeve acts as an intermediary component that introduces tapered teeth specifically for axial load handling and gear mesh delashing, while the main sector gear uses simpler spur teeth for radial load transmission. This intermediary approach allows complex functions to be added without complicating the main gear manufacturing process.
3Reliability
If tapered sector teeth are used, then gear mesh can be delashed, but tooth wear leads to excessive gear lash resulting in customer noise and rattle issues
Solution Approach 1:
The gear mesh delashing function is separated from the main sector gear teeth and placed on the eccentric sleeve. This segmentation means that wear on the sector gear spur teeth does not directly cause gear mesh lash, as the eccentric sleeve's tapered teeth maintain the mesh alignment independently. This reduces the harmful noise and rattle effects from tooth wear.
4Device complexity
If a single-piece eccentric sleeve is used, then the structure is simpler, but the device complexity increases due to the need for integral construction
Solution Approach 1:
The eccentric sleeve is segmented into multiple pieces rather than constructed as a single integral component. This segmentation simplifies manufacturing by allowing each piece to be produced separately using standard machining processes, then assembled together. The multiple-piece construction reduces the complexity of creating a single complex integral component while achieving the same functional goals.
Data Source
AI summary
An electric powered recirculating ball assembly includes a shaft having a plurality of sector teeth extending therefrom. The assembly also includes an eccentric sleeve defining a bore containing a portion of the shaft, the eccentric sleeve comprising an upper sleeve segment and a lower sleeve segment that are separate components, the eccentric sleeve defining an opening that the sector teeth extend through.