Steering Column Rack Teeth Offset to Prevent Tooth-on-Tooth Damage
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Solution Overview
Problem
Existing steering column assemblies with inter-engaging teeth face issues of permanent damage due to tooth-on-tooth alignment problems during locking, leading to unwanted movement and potential failure under high crash forces, as friction alone is insufficient to prevent movement beyond 600N.
Innovation Solution
The design incorporates a clamp mechanism with a fixed and moving rack, where the teeth are arranged to ensure that at least one pair is never in a tooth-on-tooth position, allowing for interlocking by aligning one pair while the other pair engages, preventing unwanted movement and ensuring positive locking without applying force in the direction of unlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inter-engaging teeth are used for positive locking, then reliability of locking is improved, but tooth-on-tooth alignment can cause permanent damage to teeth
Solution Approach 1:
The single row of teeth is segmented into two separate rows on the fixed rack, spaced apart from each other. This segmentation allows the moving rack to engage with the fixed rack through multiple discrete engagement points, reducing the probability that all teeth will align in a tooth-on-tooth configuration during the locking operation.
Solution Approach 2:
The two rows of teeth on the fixed rack are arranged asymmetrically with different spacing between them. The moving rack correspondsingly has two rows of teeth spaced to match this asymmetric arrangement. This asymmetric configuration ensures that when one row of teeth is in a tooth-on-tooth position, the other row is offset and can engage without damage.
2Stability of the object's composition
If massive clamp forces are applied to prevent movement under high forces, then stability is improved, but friction alone is insufficient without positive locking
Solution Approach 1:
The teeth are pre-positioned on the racks in specific patterns before the locking operation begins. The fixed rack has two rows of teeth spaced apart, and the moving rack has corresponding teeth arranged to engage with these fixed teeth. This preliminary arrangement ensures that during the locking operation, at least one row of teeth will be in a non-tooth-on-tooth position and can engage to provide positive locking, preventing the need for excessive clamp forces.
Data Source
AI summary
An adjustable steering column assembly includes a fixed rack secured to a first portion and a moving rack secured to a second portion, which are releasably engaged by a clamp mechanism to permit relative movement therebetween. The fixed rack comprises two rows of teeth spaced apart from one another and extending towards. The moving rack also comprises two rows of teeth which extend away from each other. A clamp engaging means moves the moving rack into and out of engagement with the fixed rack. The teeth on the two racks are offset relative to one another. The mechanism is further arranged so that when if a tooth on tooth event occurs the fixed rack interacts with the moving rack to cause the moving rack to move sideways to permit the teeth to become inter-engaged when the mechanism finally reaches the locked position.