Flexible Rack Teeth Prevent Steering Column Locking Damage
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Solution Overview
Problem
Existing steering column assemblies with inter-engaging teeth face issues of permanent damage and incomplete locking due to tooth-on-tooth conditions, especially when high forces are applied, leading to unwanted movement and potential damage during adjustment operations.
Innovation Solution
The design incorporates a clamp mechanism with a resiliently flexible fixed rack that can deflect in a tooth-on-tooth situation, allowing the moving rack's teeth to occupy the correct position for engagement, preventing damage and ensuring complete locking, even under high forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inter-engaging teeth are used for positive locking, then locking reliability is improved, but tooth-on-tooth alignment causes permanent damage or incomplete locking
Solution Approach 1:
The patent changes the physical state of the fixed rack teeth from rigid to resiliently flexible, allowing them to deform under load. This parameter change enables the teeth to move out of the way during tooth-on-tooth alignment, preventing permanent damage while maintaining locking reliability through the resilient recovery of the flexible teeth.
Solution Approach 2:
The resiliently flexible fixed rack teeth act as a beforehand cushioning mechanism. Before tooth-on-tooth contact can cause damage, the flexible teeth deform to absorb the impact force, preventing permanent damage to either the fixed or moving rack teeth while still allowing the locking mechanism to function.
2Device complexity
If friction-only clamping is used, then device complexity is reduced, but clamping force is insufficient to prevent movement under high loads
Solution Approach 1:
The patent segments the clamping mechanism into two distinct functional components: friction-based clamping force generation and tooth-based positive locking. This segmentation allows the friction elements to provide continuous clamping pressure while the inter-engaging teeth provide discrete positive locking positions, achieving high clamping force without excessive overall complexity.
Solution Approach 2:
The clamp mechanism combines two different locking approaches (friction and positive locking with teeth) into a composite system. The friction-based clamping provides continuous pressure while the tooth-based mechanism provides discrete positional locking, creating a hybrid system that achieves high clamping force capability without the complexity of purely mechanical tooth-based systems.
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
This solution prevents damage to the steering assembly and ensures reliable locking of the steering column, allowing for safe and complete adjustment operations, including during crashes, by allowing the teeth to flex and re-engage correctly.
Implementation Method 1
one or both of the support portion and teeth of the fixed rack are resiliently flexible so that in the event of moving from the first to the second position where a tooth-on-tooth situation arises the teeth of the moving block displace the teeth of the fixed block in the direction of movement of the moving rack
Data Source
AI summary
An adjustable steering column assembly which includes an adjustable shroud that supports a steering column shaft, a support bracket that is fixed in position in the vehicle, and a clamp mechanism that selectively secures the shroud to the support bracket, the clamp mechanism comprising a fixed rack that is secured to the shroud or the bracket, and a moving rack that is movable towards and away from the fixed rack during operation of the clamp mechanism, in which the fixed rack comprises a support portion and at least one row of teeth which are carried by the support portion arranged spaced apart from one another, and the moving rack comprises a support portion and at least one row of teeth which are carried by the support portion. One or both of the support portion and teeth of the fixed rack are resiliently flexible so that in the event of moving from the first to the second position where a tooth-on-tooth situation arises the teeth of the moving block displace the teeth of the fixed block in the direction of movement of the moving rack so that the teeth of the moving rack can occupy the region that would otherwise be occupied by the teeth of the fixed rack teeth.