Steering Column Rotation Limiter for Rotary Sensor Reliability
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Solution Overview
Problem
Conventional steer-by-wire steering systems face reliability issues due to the risk of malfunction or failure of the rotary sensor when the steering shaft exceeds the maximum steering angle, particularly under extreme conditions such as accidents or misuse, leading to a potential loss of steering functionality.
Innovation Solution
A rotation limiter with a defined threshold torque and a torque-locked connection between the steering shaft and rotary sensor, ensuring the connection remains intact even when the threshold is exceeded, allowing the rotary sensor to continue functioning by defining a higher maximum transmission torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation limiter with end stop is implemented to limit the maximum rotational angle of the steering shaft, then the steering angle is limited and realistic steering sensation is simulated, but the steering shaft or rotation limiter can be impaired (rupture or unreleasable blockage) under extreme overload conditions, causing the rotary sensor to malfunction
Solution Approach 1:
The patent designs the rotation limiter with a controlled failure mechanism where the end stop is intended to yield at a predetermined torque threshold. This beforehand cushioning ensures that under extreme overload, the end stop breaks in a controlled manner rather than causing catastrophic damage to the steering shaft or permanent blockage, thereby maintaining system reliability.
Solution Approach 2:
The patent introduces a decoupling mechanism between the rotation limiter and the rotary sensor. When the end stop breaks under overload, this intermediary mechanism allows the steering shaft to continue rotating without transmitting damaging forces to the rotary sensor, preventing sensor malfunction while maintaining steering functionality.
2Reliability
If the rotation limiter strictly prevents rotation beyond the end stop, then the maximum steering angle is limited, but under extreme overload the connection between steering shaft and rotary sensor may break, leading to loss of steering control
Solution Approach 1:
The patent designs the connection between the steering shaft and rotary sensor with sufficient strength to withstand the threshold torque of the rotation limiter. This beforehand cushioning ensures that under normal overload conditions, the connection remains intact while the end stop yields, preventing loss of steering control.
Solution Approach 2:
The patent introduces a decoupling mechanism that acts as an intermediary between the rotation limiter and the rotary sensor. When the end stop breaks under extreme overload, this intermediary allows the steering shaft to continue rotating without transmitting damaging forces to the rotary sensor, maintaining the connection integrity and steering control.
Data Source
AI summary
The present disclosure relates to a steering column for a motor vehicle, comprising a steering shaft which is mounted so as to be rotatable about its longitudinal axis (L) relative to a carrying unit, a rotation limiter having an end stop for limiting the rotation of the steering shaft, and a rotary sensor coupled to the steering shaft by means of a torque-locked connection. In order to permit a greater operational reliability, the invention proposes that the rotation limiter has a threshold torque and, if said threshold torque is exceeded, the rotation of the steering shaft beyond the end stop is permitted, wherein the threshold torque is less than a maximum transmission torque of the connection between the steering shaft and rotary sensor.