Linear Worm Gear Assembly for Precise Friction Setting
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Solution Overview
Problem
Existing power steering assemblies with worm and worm gear sets face issues of binding and dimensional stack-up due to relative movement between housings, affecting the precision of friction setting and assembly alignment.
Innovation Solution
A power steering assembly design featuring a worm gear axis bearing that protrudes from the first housing and is received by an aperture in the second housing, with flat portions on the aperture wall engaging the rounded exterior of the bearing, allowing for precise alignment and rotation without binding, and secured with mechanical fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear movement assembly processes are used to adjust friction setting, then the friction can be adjusted to desired levels, but binding and dimensional stack-up issues occur
Solution Approach 1:
A dedicated bearing is introduced as an intermediary component between the worm gear housing and the worm housing. This bearing receives the worm gear axis and provides a stable reference, mediating the relationship between the two housings to prevent binding while maintaining precise friction settings.
Solution Approach 2:
The assembly is segmented into distinct functional components: the worm gear housed in one housing, the worm in another housing, and a separate bearing component. This segmentation allows each component to be optimized independently and assembled with precise alignment, reducing dimensional stack-up.
2Adaptability or versatility
If separate housings are used for worm and worm gear, then friction adjustment is enabled, but dimensional stack-up increases
Solution Approach 1:
The bearing is pre-installed in the worm gear housing to establish a precise reference position before the second housing is attached. This preliminary action ensures that when the housings are assembled, the alignment is already determined by the bearing's precise location, minimizing dimensional stack-up.
Solution Approach 2:
The bearing acts as an intermediary reference element that defines the precise relationship between the two housings. By using this intermediate component with known dimensions and precise fit, the overall dimensional accuracy of the assembled housing is improved.
3Ease of operation
If three points of contact are used between housings, then relative movement is enabled for adjustment, but binding occurs
Solution Approach 1:
The adjustment capability is extracted from the housing-to-housing interface and relocated to the interface between the worm gear and the bearing. The bearing's rounded exterior engaging with flat portions allows controlled movement for adjustment while preventing binding, separating the adjustment function from the structural housing connection.
Data Source
AI summary
A power steering assembly includes a first housing containing a worm gear operatively coupled to a steering shaft, the worm gear rotatable about a worm gear axis. The power steering assembly also includes a second housing containing an electric motor and a worm arranged to engage the worm gear. The power steering assembly further includes a worm gear axis bearing disposed between the worm gear and an inner surface of the first housing, the worm gear axis bearing protruding from the second housing to position the first housing relative to the worm gear axis.