Steering Column Adjustable Bearing Surfaces
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Solution Overview
Problem
Current collapsible steering column assemblies rely solely on friction for locking, which is inadequate when high forces are applied, leading to potential movement and rotation issues during normal use and crashes.
Innovation Solution
A steering column assembly with a telescopic shroud and clamp mechanism featuring adjustable bearing surfaces that allow precise setting of rotational free play, ensuring the inner and outer shroud portions remain stable during normal use and collapse effectively during crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a clamp mechanism relies solely on friction for locking, then the device complexity is reduced, but the reliability deteriorates when very high forces are applied
Solution Approach 1:
The locking function is divided into two independent systems: a friction-based clamp mechanism for general positioning and a separate positive locking system with block and clamp rail for secure locking. This segmentation allows each system to specialize in its optimal function without compromising the other.
Solution Approach 2:
The locking system combines two different locking mechanisms (friction-based clamping and positive mechanical interlocking) into a composite system, where each mechanism compensates for the weaknesses of the other, providing both ease of operation and high-force reliability.
2Reliability
If the clamp mechanism is made more robust to prevent movement under high forces, then the reliability improves, but the ease of operation deteriorates due to increased adjustment effort
Solution Approach 1:
The adjustment and locking functions are separated into distinct operational phases. The clamp mechanism provides easy initial positioning through friction, while the positive locking system provides secure final locking. This segmentation allows easy adjustment without compromising final stability.
Solution Approach 2:
The friction-based clamp mechanism performs preliminary positioning and stabilization before the positive locking system is engaged. This preliminary action reduces the effort required for final locking while ensuring stability under high forces.
3Reliability
If the bearing surfaces are made adjustable to precisely control rotational free play, then the manufacturing precision deteriorates due to additional adjustment steps, but the reliability improves
Solution Approach 1:
The bearing element is designed with adjustable positioning capability, allowing the rotational free play to be dynamically tuned during assembly. This adjustability compensates for manufacturing tolerances and ensures reliable rotational stability without requiring ultra-precise manufacturing.
Data Source
AI summary
A steering column assembly is disclosed comprising a telescopic shroud having an outer shroud portion and an inner shroud portion with an end that extends into the outer shroud portion. A plate is fixed to the inner shroud portion and includes a slot that extends axially along the inner shroud portion. A block is releasably interlockable with the plate to prevent telescopic motion of the inner shroud portion relative to the outer shroud portion. The steering column assembly includes a clamp assembly operable between a clamped condition in which the outer shroud portion clamps around the inner shroud portion and an unclamped condition in which the outer shroud portion is unclamped from the inner shroud portion. Four bearing surfaces are arranged in two facing pairs, one bearing surface of each facing pair being associated with the inner shroud portion and the other bearing surface of each facing pair being associated with the outer shroud portion, at least one adjustable bearing element including a respective one of said bearing surfaces. The adjustable bearing element is adjustable relative to one of the inner shroud portion or outer shroud portion for setting the amount rotational free play between the inner shroud portion and outer shroud portion when the assembly is in an unclamped condition.