Collapsible Steering Column Blocking Part Load Path
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Solution Overview
Problem
Existing collapsible steering column assemblies risk damaging frangible connectors when high axial adjustment forces are applied, leading to partial or full disengagement from the vehicle during extreme travel, which can cause the connectors to break or shear, compromising the controlled collapse mechanism during a crash.
Innovation Solution
Incorporating a blocking part with a dual-load path mechanism that redirects axial loads away from frangible connectors when the clamp mechanism is unlocked, using a weaker section that breaks under lower loads and a stronger section that handles higher loads, ensuring the connectors are protected during adjustments and allowing controlled collapse during a crash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clamp mechanism is unlocked and high axial adjustment force is applied, then the steering column can be adjusted to extreme positions, but the frangible connectors may be damaged or sheared
Solution Approach 1:
The blocking part acts as an intermediary element between the clamp mechanism and the frangible connectors. When the clamp mechanism is unlocked and adjustment force is applied, the blocking part intercepts the load through its blocking surface, preventing the force from being transmitted to the frangible connectors. This mediator role allows full adjustment range while protecting connector integrity.
Solution Approach 2:
The load path is segmented into two distinct pathways: one through the frangible connectors for crash collapse, and another through the blocking part for adjustment operations. The blocking part creates a separate load-bearing path that diverts adjustment forces away from the frangible connectors, allowing independent optimization of both adjustment reliability and crash protection.
2Reliability
If the frangible connectors are made stronger to prevent damage during adjustment, then connector reliability improves, but the controlled collapse mechanism during crash is compromised
Solution Approach 1:
The blocking part is designed with differentiated local properties: a strong blocking surface that can withstand high adjustment forces, and a deliberately weaker connection to the support bracket that allows controlled collapse. This local quality differentiation enables the same structure to provide both protection during adjustment and controlled failure during crash.
Solution Approach 2:
The system dynamically switches between two operational modes: during normal adjustment, the blocking part carries the load; during crash, the blocking part fails and the frangible connectors carry the load enabling controlled collapse. This dynamic behavior allows the system to adapt its load path based on operational conditions.
3Reliability
If a blocking part is added to create an additional force path, then connector protection during adjustment is achieved, but device complexity increases
Solution Approach 1:
The blocking part is merged with existing structural elements of the steering column assembly, such as the support bracket or mounting bracket. By integrating the blocking function into existing components rather than adding completely separate elements, the design achieves connector protection while minimizing increases in overall device complexity.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A collapsible steering column assembly for a vehicle comprises a shroud (1, 2)which surrounds a steering column shaft, a mounting bracket secured to or integral with a fixed part of the vehicle, a support bracket (3) secured to the mounting bracket through one or more frangible connectors (5), a clamp mechanism (9) which releasably secures the shroud (1, 2) to the support bracket (3), and a blocking part (14) which is fixed in position relative to the mounting bracket and at least in an undamped condition of the clamp mechanism (9) provides an additional force path between the clamp mechanism (9) and the mounting bracket that does not pass through the support bracket (3). In the event that an axial load is applied to the steering assembly when the clamp mechanism (9) is unlocked and has reached the end of its allowable travel at least some of the load is carried through the clamp mechanism (9) and the blocking part (14) to the mounting bracket along the additional force path.