Steering Column Rotation Limiter That Protects the Rotary Sensor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing steering columns in steer-by-wire systems lack sufficient operational safety, particularly when subjected to extreme steering torques during accidents or misuse, which can lead to failure of the rotary sensor and loss of steering control.
Innovation Solution
The steering system incorporates a rotary limiter with a defined border moment and a target breaking device, ensuring that the connection between the steering shaft and the rotary sensor remains intact even under overload conditions, thereby maintaining steering functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotation limiter with end stop is added to limit the maximum rotation of the steering shaft, then the steering angle is limited and realistic steering feel is simulated, but the steering shaft or rotation limiter may break or become permanently blocked under extreme torque, causing the rotation sensor to fail
Solution Approach 1:
The rotation limiter is segmented into two independent functional parts: the end stop mechanism for normal operation and the predetermined breaking device for overload protection. This segmentation allows the end stop to limit steering angle during normal use while the breaking device provides a safety release path under extreme torque, preventing damage to the rotation sensor.
Solution Approach 2:
The predetermined breaking device acts as an intermediary safety mechanism between the rotation limiter and the rotation sensor. When extreme torque exceeds the limit torque, the breaking device activates to release the rotation limiter, preventing the transmission of damaging forces to the rotation sensor while maintaining sensor functionality.
2Strength
If the limit torque of the rotation limiter is increased to withstand higher steering torques, then the rotation limiter can handle more extreme conditions, but the connection between the steering shaft and rotation sensor may break, causing total steering system failure
Solution Approach 1:
The predetermined breaking device is pre-configured with a breaking torque value that is lower than the maximum transmission torque of the steering shaft-rotation sensor connection. This preliminary setup ensures that under extreme overload conditions, the breaking device will activate first to release the rotation limiter, preventing the transmission of damaging forces to the rotation sensor and maintaining steering system functionality.
3Reliability
If the connection between the steering shaft and rotation sensor is made stronger to prevent breaking, then the rotation sensor remains functional under higher torques, but the rotation limiter cannot effectively limit the steering angle without risking sensor damage
Solution Approach 1:
The system utilizes parameter differentiation between limit torque and maximum transmission torque. The limit torque of the rotation limiter is set lower than the maximum transmission torque of the steering shaft-rotation sensor connection, creating a safety margin. This parameter change allows the rotation limiter to effectively limit steering angle during normal operation while the predetermined breaking device provides an additional safety layer to protect the rotation sensor under extreme conditions.
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
The present invention relates to a steering column (1) for a motor vehicle, comprising a steering shaft (23), which is mounted so as to be rotatable about its steering shaft longitudinal axis (L) relative to a carrying unit (3), a rotation limiter (5) having an end stop for limiting the rotation of the steering shaft (23), and a rotary sensor (7) coupled to the steering shaft (23) by means of a torque-locked connection. In order to permit greater operational reliability, the invention proposes that the rotation limiter (5) has a threshold torque and if said threshold torque is exceeded, the rotation of the steering shaft (23) beyond the end stop is permitted, the threshold torque being less than a maximum transmission torque of the connection between the steering shaft (23) and rotary sensor (7).