Steer-by-Wire Steering Shaft Locking via Mechanical Travel Limits
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Solution Overview
Problem
Steer-by-wire systems lack a mechanism to prevent the steering wheel from turning when a driver enters or exits the vehicle, as they do not have a physical connection to the vehicle wheels, which is typically addressed by Electronic Steering Column Locks (ESCL), but this solution is not always necessary or desirable.
Innovation Solution
A steer-by-wire system with a mechanical stop defining end-to-end travel limits for the steering shaft, allowing the controller to rotate the shaft based on preset conditions such as vehicle shutdown, driver absence, or mode changes, effectively locking the steering wheel in place without the need for an ESCL by setting travel limits in specific directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an Electronic Steering Column Lock (ESCL) is used to prevent steering wheel rotation, then the steering wheel is locked when the driver enters or exits, but the device complexity increases and additional locking mechanisms are required
Solution Approach 1:
The patent extracts the locking function from a separate ESCL mechanism and integrates it into the normal steering operation. The steering shaft's mechanical stop and controller work together to provide locking capability without requiring an additional dedicated locking mechanism, thereby reducing device complexity while maintaining steering wheel stability
Solution Approach 2:
The steering shaft is designed to serve multiple functions: normal steering operation and anti-roll locking. By making the steering shaft multi-functional, the patent eliminates the need for a separate ESCL, reducing overall system complexity while maintaining the reliability of steering wheel stabilization
2Ease of operation
If the steering shaft rotation is fully unrestricted, then the steering wheel can rotate freely for normal operation, but the steering wheel may rotate uncontrollably when the driver enters or exits the vehicle
Solution Approach 1:
The patent implements dynamic control of the steering shaft rotation. The mechanical stop provides fixed physical limits, while the controller dynamically adjusts the rotation range based on detected conditions (normal driving vs. driver entry/exit), allowing full rotation during operation and preventing rotation during entry/exit
Solution Approach 2:
The system uses feedback from sensors to detect driver presence and steering shaft position. This feedback enables the controller to automatically adjust the steering shaft rotation limits, preventing uncontrolled rotation during driver entry/exit while maintaining full maneuverability during normal operation
3Object-affected harmful factors
If a mechanical stop is added to define travel limits, then the steering shaft rotation is constrained to prevent uncontrolled rotation, but the device complexity increases
Solution Approach 1:
The patent merges the mechanical stop function with the existing steering shaft structure. Rather than adding a completely separate locking mechanism, the mechanical stop is integrated into the steering shaft assembly, working in conjunction with the controller to provide rotation limits with minimal additional complexity
Data Source
AI summary
A steer-by-wire system comprises a steering shaft connected to a steering wheel; and a mechanical stop defining end-to-end travel limits of the steering shaft, the end-to-end travel limits comprising a first travel limit end of a first direction and a second travel limit end of a second direction opposite to the first direction. A controller rotates, in response to a signal related to first preset condition(s), the steering shaft toward the first direction until the steering shaft reaches the first travel limit end. And, the controller rotates, in response to a signal related to second preset condition(s), the steering shaft toward the second direction until the steering shaft reaches the second travel limit end. The system can prevent the rotation of the steering wheel using end-to-end travel limits of a mechanical stop of the steering shaft without a locking mechanism when the driver enters or exits the vehicle.