Steering Column Frangible Pin Side Load Management
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Solution Overview
Problem
Existing collapsible steering column assemblies face challenges in ensuring safe collapse during crashes while preventing accidental movement or breakage during normal use, particularly due to the risk of frangible connectors snapping under side loads.
Innovation Solution
A steering column assembly featuring a toothed block and clamp mechanism with a frangible pin, carrier element, and side rails, allowing the toothed block to move sideward and axially during crashes while locking in place during normal use, and incorporating an energy-absorbing system to manage collapse and distribute loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the toothed block is rigidly connected to the carrier element, then the clamp mechanism provides strong locking during normal use, but the frangible pin may snap under side loads during crashes
Solution Approach 1:
The connection between the toothed block and carrier element is divided into two functional parts: the frangible pin provides axial locking strength during normal use, while the clearance between the pin and bore walls allows side-to-side movement during crashes, preventing pin snapage
Solution Approach 2:
Different regions of the connection interface have different properties: the pin-bore interface provides strong axial engagement for locking, while the side-to-side clearance provides flexibility for crash conditions, allowing each region to optimize for its specific function
2Adaptability or versatility
If the toothed block is allowed to move freely, then the steering column can collapse during crashes, but the clamp mechanism cannot maintain stability during normal driving
Solution Approach 1:
The connection system dynamically transitions from a rigid locked state during normal use to a flexible collapsed state during crashes, with the frangible pin maintaining axial engagement while allowing lateral movement when needed
3Reliability
If the frangible pin is made robust to prevent breaking, then the clamp mechanism remains reliable, but the toothed block cannot move sideward to prevent binding during crashes
Solution Approach 1:
The pin-bore interface is segmented into two functional zones: a locked zone providing axial engagement for reliability, and a clearance zone enabling lateral movement for ease of operation during crashes
Solution Approach 2:
The connection interface has non-uniform properties: the pin provides strong axial locking where needed, while the bore walls provide lateral clearance where movement is required, allowing the system to satisfy both reliability and ease of operation
Data Source
AI summary
A steering column assembly comprises a telescopic shroud having an outer shroud portion and an inner shroud portion, a clamp rail fixed to the inner shroud portion, a clamp bolt that extends perpendicular to the shroud, a toothed block that is connected to the clamp bolt and is displaced on rotation of the clamp bolt, and a carrier element that supports the toothed block and is movable in response to rotation of the clamp bolt to in turn move the toothed block between a clamped position and an unclamped position and is free to move from side to side relative to the slot. A frangible pin secures the toothed block to the carrier element, the frangible pin having a first end located in a bore in the toothed block and a second end located in a bore in the carrier element, the toothed block being supported on a shoulder of the frangible pin, and a clearance is provided between the frangible pin and the walls of one of the bores to permit side to side movement of the toothed block relative to the carrier element.