Steering Wheel Rotation Limiter Using Spiral Groove End Stops
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Solution Overview
Problem
Prior steer-by-wire systems have complex structures and are limited in functionality and adaptability to different vehicle requirements, lacking a robust and reliable solution for limiting the maximum angle of rotation.
Innovation Solution
A steer-by-wire steering system with a torque feedback device and a steering wheel rotation limiting device that includes an electric machine with a rotor and stator, and a sliding element with a spiral groove, allowing for mechanical limitation of steering wheel rotation without a natural end-stop structure, enabling rotation beyond 360° while preventing oversizing of the electric machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical end-stop structure is used to limit steering wheel rotation, then the maximum angle of rotation is limited, but the structure becomes complex and reliability decreases
Solution Approach 1:
The invention extracts the rotation limiting function from complex mechanical end-stop structures and implements it through a simplified mechanism consisting of a limiting member with a cam surface and a follower. This extraction principle resolves the contradiction by removing unnecessary structural complexity while maintaining reliable rotation angle limitation.
Solution Approach 2:
The invention replaces traditional complex mechanical end-stop structures with a cam-follower mechanism that achieves the same rotation limiting function with simpler components. The cam surface profile directly controls the steering wheel rotation angle, substituting complex multi-component mechanical stops with a streamlined mechanical system.
2Reliability
If the electric machine is oversized to prevent steering wheel rotation beyond desired angle, then rotation control is achieved, but system size and cost increase
Solution Approach 1:
The invention introduces a mechanical intermediary (the cam-follower limiting mechanism) that acts between the steering wheel and the electric machine. This intermediary physically limits the rotation angle regardless of electric machine size, allowing a smaller, more compact electric machine to be used while maintaining reliable rotation control.
3Reliability
If conventional mechanical connections are used between steering wheel and wheels, then mechanical power transmission is reliable, but installation space and design flexibility are reduced
Solution Approach 1:
The invention replaces direct mechanical connections between the steering wheel and wheels with an electro-mechanical system. Sensors detect steering wheel position and send signals to actuators that control wheel orientation, substituting mechanical power transmission with electronic control. This enables greater design flexibility and adaptability while maintaining reliable steering control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a robust and reliable mechanical end-stop function, reduces complexity and manufacturing costs, allows flexible integration into various vehicles, and adapts to different requirements, while maintaining system efficiency and reducing friction and inertia.
Implementation Method 1
The sliding element comprises a projection that engages a spiral groove formed on a circumferential surface of the steering wheel hub so that rotation of the steering wheel hub causes axial movement of the sliding element
Implementation Method 2
The torque feedback device can be operated to produce resistance torque to the rotation of the steering wheel so as to simulate the resistance torque present in conventional steering systems
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present disclosure relates to a steering system (10) comprising a steering wheel rotation limiting device (52) being arranged radially offset to the steering wheel hub (14) and comprising a base (54) being fixed to the or another non-rotatable component (26) of the steering system (10), the base (54) comprising two opposing end stop surfaces (60, 62), and comprising a sliding element (56) being axially slidable parallel to the axis of rotation relative to the base (54) and relative to the steering wheel hub (14) between the two opposing end stop surfaces (60, 62). The sliding element (56) comprises a projection (64) that engages a spiral groove (66) formed on a circumferential surface of the steering wheel hub (14) so that rotation of the steering wheel hub (14) causes axial movement of the sliding element (56), and so that abutment of the sliding element (56) with one of the two end stop surfaces (60, 62) blocks movement of the sliding element (56) and rotation of the steering wheel hub (14).