Steering Column Absorption Strap Bidirectional Locking
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Solution Overview
Problem
Existing steering column systems require separate hardware for adjustment lock and crashworthiness lock, leading to structural weakness and increased mass due to the need for additional ribs and thicker walls, and typically function only in one direction, necessitating a separate set of hardware for bidirectional locking.
Innovation Solution
An energy absorption strap assembly with a rocker plate and clamp assembly that provides bidirectional locking through staggered teeth engagement, eliminating the need for a large aperture in the lower jacket and allowing for internal clamping components, thus enhancing structural integrity and reducing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large aperture is used in the lower jacket to access the strap, then the eccentric cam can access the strap, but the structural integrity of the lower jacket is weakened
Solution Approach 1:
The clamp assembly and rocker plate are nested within the lower jacket structure, with the rocker plate positioned inside the lower jacket and the clamp assembly operating within the same space. This eliminates the need for a large aperture in the lower jacket, as all components are accessed and operated from within the existing structural boundaries, maintaining structural integrity while enabling full functionality.
Solution Approach 2:
The rocker plate acts as an intermediary component between the clamp assembly and the energy absorption strap. It translates the clamping motion into the necessary movement to engage or disengage the strap, allowing the system to function without requiring direct access through a large aperture in the lower jacket.
2Strength
If ribs and thicker walls are added to compensate for structural weakness, then the lower jacket strength is improved, but the mass and material cost increase
Solution Approach 1:
The problematic large aperture is extracted/removed from the lower jacket design. By eliminating the aperture requirement, the lower jacket can be designed as a solid, continuous structure without needing additional ribs or thicker walls to compensate for structural weaknesses, thereby reducing mass and material cost while maintaining strength.
3Adaptability or versatility
If an eccentric cam system is used, then the locking function is achieved, but the system works in only one direction requiring separate hardware for bidirectional locking
Solution Approach 1:
The rocker plate with staggered teeth and clamp assembly design provides universal functionality for both extension and retraction directions. The staggered teeth arrangement on the rocker plate allows the clamp assembly to engage and lock the energy absorption strap in either direction of movement, eliminating the need for separate hardware sets for bidirectional locking and simplifying the overall system configuration.
4Adaptability or versatility
If two separate systems of hardware are used for adjustment lock and crashworthiness lock, then both functions are provided, but the device complexity increases
Solution Approach 1:
The adjustment lock and crashworthiness lock functions are merged into a single integrated system. The clamp assembly serves dual purposes: it provides adjustment locking during normal operation and activates the energy absorption strap during crashworthiness events. This consolidation eliminates the need for two separate hardware systems, reducing overall device complexity while maintaining both required functions.
Data Source
AI summary
An energy absorption strap assembly includes an energy absorption strap coupled to an upper jacket and positioned along an inner surface of a lower jacket of the steering column assembly, the energy absorption strap having a base extending along a longitudinal direction of the energy absorption strap. Also included is a rocker plate having a pivot region seated on the base of the energy absorption strap and tiltable thereon. Further included is a clamp assembly for fixing a telescoping position of the steering column assembly, the clamp assembly having a clamp jaw, wherein movement of the clamp jaw provides a meshed engagement between teeth of the clamp jaw and teeth of the rocker plate.