Steering Column Intermediate Rotor Rotation Limit
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Solution Overview
Problem
Steer-by-wire systems in autonomous vehicles lack a mechanism to limit the rotational range of the steering wheel, allowing it to rotate indefinitely when the vehicle wheels are at their maximum steering angle, which is not physically connected to the steering wheel, posing a safety concern.
Innovation Solution
A steering column assembly with a housing, a rotatable shaft, an engagement portion, and end stop means, including intermediate rotors and rotatable bodies that limit the steering wheel's rotation through predetermined angles, allowing for more than a complete half-turn rotation before stopping, with optional elastomeric materials and resilient coatings for reduced noise and improved contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a steer-by-wire system is used without rotational limit mechanism, then the steering wheel can rotate freely providing operational flexibility, but the steering wheel may rotate indefinitely beyond the vehicle's maximum steering angle creating safety hazards
Solution Approach 1:
The patent introduces an intermediate rotor as a mediator between the shaft and the engagement portion. This intermediate rotor is independently rotatable relative to the shaft and transmits rotation only within a limited angular range, thereby mediating between the driver's steering input and the steering actuator while preventing excessive rotation that would compromise safety.
Solution Approach 2:
The rotational limitation mechanism is segmented into multiple independent components: the shaft, the independently rotatable intermediate rotor, the engagement portion, and the end stop means. This segmentation allows each component to perform its specific function - the intermediate rotor handles the limited rotation transmission, while the engagement portion and end stop means provide the rotational boundary, collectively solving the contradiction between operational freedom and safety.
2Reliability
If end stop means is mounted to limit shaft rotation, then steering wheel rotation is limited to match vehicle steering capability, but the mechanism becomes more complex with additional components
Solution Approach 1:
The patent merges the rotational limitation function with the existing steering column components. The engagement portion is integrated into the shaft assembly, and the end stop means is mounted to the housing, combining the limitation mechanism with the structural elements already present in the steering column, thereby reducing the perceived complexity despite adding functional capability.
Solution Approach 2:
The intermediate rotor is configured to be independently rotatable relative to the shaft, allowing it to automatically engage and disengage from the engagement portion based on the rotation angle. This self-service mechanism eliminates the need for external control systems or complex actuation mechanisms, achieving rotational limitation through the inherent mechanical properties of the components themselves.
Data Source
AI summary
A steering column assembly for a vehicle includes a housing, a shaft rotatably mounted with respect to the housing and being configured for attachment of a steering wheel at one end, an engagement portion connected to and configured to rotate with the shaft, and end stop means which is mounted to the housing and is located in the path of an intermediate rotor which is mounted to the shaft and which is configured to be independently rotatable relative to the shaft, the intermediate rotor being simultaneously engageable with both the engagement portion and with the end stop upon rotation of the shaft through a predetermined angle.