Steer-by-Wire End Stop Bracket for Rotational Travel Limit
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Solution Overview
Problem
Steer-by-wire steering columns lack a rotational stop mechanism to protect components like the airbag coil, as they do not have an intermediate shaft, and existing end of travel ring systems require a positive stop within the steering column's upper jacket.
Innovation Solution
A steering column assembly with a jacket and an end stop assembly that includes a bracket formed of harder material than the jacket, positioned to contact a stop ring at the end of rotational travel, providing a strong and non-deformable interface to limit steering shaft rotation and protect adjacent components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotational stop mechanism is added to protect components like the airbag coil in steer-by-wire steering columns, then component safety is improved, but device complexity increases
Solution Approach 1:
The end stop assembly is integrated into the upper jacket structure, combining the stop function with the existing jacket component rather than adding a separate independent mechanism. This reduces overall device complexity while maintaining component safety.
Solution Approach 2:
The bracket serves as an intermediary element between the upper jacket and the stop ring, providing a positive stop interface that protects the airbag coil without requiring direct integration into the jacket or shaft structure.
2Ease of manufacture
If the end stop assembly uses a softer material matching the jacket, then manufacturing ease is improved, but the stop interface becomes deformable under high turning torque
Solution Approach 1:
The bracket is formed of a material that is harder than the jacket material on a durometer scale, creating a localized hard stop interface at the contact point while the rest of the jacket maintains its original material properties for ease of manufacture.
Solution Approach 2:
The end stop assembly uses composite construction with a bracket made of harder material (such as metal or hard polymer) embedded in or attached to the softer jacket material, combining the manufacturability of the softer material with the strength of the harder material at the critical stop interface.
3Strength
If the bracket material is harder than the jacket material, then the stop interface withstands higher turning torque, but manufacturing precision requirements increase
Solution Approach 1:
The end stop assembly is segmented into separate components (jacket and bracket) that can be manufactured independently with their respective material properties, allowing the harder bracket to be precision-manufactured separately and then integrated into the jacket structure.
Data Source
AI summary
A steering column assembly includes a jacket extending longitudinally about a jacket axis, the jacket defining an opening extending radially completely through the jacket. The steering column assembly also includes an end stop assembly disposed in the opening and protruding radially inwardly. The steering column assembly further includes a steering shaft, at least a portion of the steering shaft disposed within the jacket and extending longitudinally about the jacket axis. The steering column assembly yet further includes a stop ring mounted to the steering shaft, the stop ring positioned to contact the end stop assembly at an end of rotational travel position of the steering shaft.