Telescopic Steering Column Support Assembly for Free Play Control
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Solution Overview
Problem
Conventional telescopic steering column assemblies face challenges in achieving the minimum natural vibration frequency, leading to steering wheel shake due to engine vibrations or road roughness, as the bending stiffness of the shafts is compromised by the need for sliding interfaces to allow for telescopic adjustment.
Innovation Solution
A support assembly with resiliently-deformable legs is interposed between the outer and inner shroud portions, providing a biasing force to maintain alignment and increase natural frequency, while allowing low-friction axial and rotational motion, comprising a body portion with legs that extend from it to engage both shroud and shaft portions, ensuring consistent feel and reduced sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a sliding interface is used to allow telescopic adjustment, then the steering column can be adjusted for reach and height, but the bending stiffness of the shafts is compromised and natural vibration frequency decreases
Solution Approach 1:
A support assembly with resiliently-deformable legs is introduced as an intermediary element between the outer shaft portion and inner shroud portion. The legs engage both components and provide elastic support that maintains alignment and increases bending stiffness while still permitting the necessary telescopic movement, thus resolving the contradiction between adjustability and structural stability
Solution Approach 2:
The resiliently-deformable legs change the mechanical parameters of the system by providing elastic compliance rather than rigid constraint. This allows the system to maintain higher natural vibration frequency through the elastic support while still enabling the telescopic adjustment range required for adaptability
2Ease of operation
If clearances are provided in the sliding interface to allow free telescopic movement, then the steering column can adjust smoothly, but free play occurs between the shaft and shroud
Solution Approach 1:
The resiliently-deformable legs transform the clearance-based adjustment mechanism into one that maintains continuous elastic contact. The legs deform elastically during adjustment, providing smooth movement while eliminating free play through the constant elastic force, thus improving both ease of operation and reliability
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 support assembly enhances the natural frequency of the steering column, reducing noise, vibration, and harshness (NVH) by eliminating free play and providing a high-quality feel during telescopic adjustment and rotation.
Implementation Method 1
a plurality of resiliently-deformable legs extending away from the body portion to engage the other of the outer shaft portion and the inner shroud portion, the resiliently-deformable legs, in use, applying a biasing force between the outer shaft portion and inner shroud portion
Data Source
AI summary
A telescopic steering column assembly comprises a telescopic shroud having an inner shroud portion and an outer shroud portion, and a telescopic steering shaft that passes through the shroud, comprising an inner shaft portion and an outer shaft portion. The telescopic steering shaft is supported by the shroud through a support assembly interposed between the outer shaft portion and the inner shroud portion, which in use, limits or removes free play between the telescopic steering shaft and the shroud that would otherwise occur in at least one direction orthogonal to the telescopic movement.