Steering Column Toothed Block Locking Mechanism
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Solution Overview
Problem
Existing collapsible steering column assemblies face issues with maintaining a positive lock during crashes, as friction-based clamp mechanisms are insufficient to resist high forces, leading to potential damage from excessive bolt tensions and alignment challenges during adjustments.
Innovation Solution
A steering column assembly featuring a toothed block and slot system with a biasing spring, allowing the toothed block to engage optimally with the slot teeth during crashes, and a frangible connection to facilitate axial movement, ensuring secure locking without lateral displacement and preventing tooth-on-tooth alignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If friction-based clamp mechanisms are used to prevent movement, then the structure is simple and easy to operate, but the mechanism cannot resist high forces (up to 2000N or higher) applied during crashes
Solution Approach 1:
The clamp mechanism is segmented into multiple functional components: a clamp bolt for applying radial clamping force, a toothed block with engagement teeth for positive locking, and a biasing spring for maintaining tooth engagement. This segmentation allows each component to specialize in a specific function, achieving high force resistance through the combined action of friction (clamp bolt) and positive mechanical locking (toothed block), rather than relying on friction alone.
Solution Approach 2:
The toothed block acts as an intermediary element between the clamp bolt and the shroud. It translates the radial clamping force from the clamp bolt into axial locking force through its engagement teeth, while the biasing spring serves as an intermediary that ensures continuous contact and proper engagement between the teeth. This intermediary mechanism enables the system to resist high crash forces effectively.
2Force
If massive clamp forces are applied to achieve positive locking, then force resistance improves, but the risk of damage from excessive bolt tensions increases
Solution Approach 1:
Instead of relying solely on increasing clamp bolt tension to achieve positive locking, the invention inverts the approach by using the toothed block engagement as the primary locking mechanism. The clamp bolt applies only sufficient force to press the teeth together, while the geometric interlocking of the teeth provides the majority of the locking force. This inversion dramatically reduces the required bolt tension while maintaining or improving force resistance.
Solution Approach 2:
The invention changes the parameter of force application from high-tension axial clamping to low-tension radial clamping combined with mechanical interlocking. The biasing spring optimizes the contact pressure between teeth, ensuring effective engagement without requiring excessive clamp bolt tension. This parameter change allows the system to achieve positive locking with much lower bolt tensions, reducing the risk of damage.
3Manufacturing precision
If the toothed block is constrained to prevent lateral movement, then locking precision improves, but the ability to accommodate manufacturing tolerances and alignment variations deteriorates
Solution Approach 1:
The toothed block is designed with dynamic characteristics that allow it to adapt to alignment variations. The biasing spring provides a compliant connection that enables the toothed block to self-adjust its position laterally within the slot while maintaining tooth engagement. This dynamic design allows the system to accommodate manufacturing tolerances and alignment variations automatically, eliminating the need for precise pre-alignment during assembly.
Solution Approach 2:
The toothed block performs self-alignment through its interaction with the slot and biasing spring. As the clamp mechanism is assembled and the clamp bolt is tightened, the biasing spring automatically positions the toothed block laterally within the slot to achieve optimal tooth engagement. This self-service mechanism eliminates the need for manual alignment adjustments and ensures reliable locking despite variations in manufacturing precision.
4Adaptability or versatility
If the toothed block is allowed to move freely within the slot, then adaptability to alignment variations improves, but unwanted lateral displacement during normal use increases
Solution Approach 1:
The biasing spring acts as a counterbalancing element that applies a lateral force to the toothed block, pressing it against one side of the slot. This counterforce prevents the toothed block from moving freely within the slot during normal use, ensuring positional stability and preventing unwanted lateral displacement. The spring force is calibrated to provide sufficient restraint under normal conditions while still allowing the block to self-align during assembly.
Solution Approach 2:
The biasing spring applies a partial restraining force that is sufficient to prevent lateral movement during normal use but allows enough freedom for the toothed block to self-align during assembly. The spring force is designed to be excessive enough to ensure stable positioning under operating conditions, yet controlled enough to permit automatic alignment when the mechanism is first assembled or adjusted.
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 solution provides a reliable positive locking mechanism that prevents axial movement during normal use while allowing controlled collapse during crashes, reducing the risk of damage and improving user experience by ensuring smooth engagement and disengagement without requiring manual realignment.
Implementation Method 1
the carrier includes a biasing spring which, when the assembly is in the unclamped position, biases the toothed block in a direction substantially perpendicular to the movement between the clamped and unclamped positions, towards the teeth of the first side of the slot
Implementation Method 2
the teeth of the two rows of teeth of the slot and the teeth of the two rows of teeth of the toothed block are shaped such that for any given position of the inner shroud portion relative to the outer shroud portion the toothed block is free to move into the slot when the carrier is in moved into the clamped position from the unclamped
Data Source
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AI summary
Asteering column assembly is provided that includes an inner shroud portion and an outer shroud portion, the inner shroud portion extending into the outer shroud portion and including a rail. The rail includes a slot with two opposing sides, each of which has teeth. A toothed block is provided that engages with the teeth of the slot, when a clamping mechanism is actuated. The toothed block is supported by a carrier that allows the toothed block to be free to move from side-to-side when engaged with the slot, and the teeth of the slot and the toothed block are shaped such that the toothed block may engage the teeth of the slot at any position when the clamping mechanism is actuated.The teeth of a first side of the slot prevent the block from moving in a collapse direction of the assembly and the teeth of the second side of the slot permit movement in a collapse direction but apply a thrust towards the teeth of the first side. The carrier includes a biasing spring that urges the toothed block towards the first side of the slot.