Steer-by-Wire Steering Shaft Stopper for Realistic Steering Feel
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Solution Overview
Problem
Steer-by-wire steering devices lack mechanical connection between the steering shaft and the wheels, leading to indefinite rotation of the steering wheel and poor steering feel when the driver applies a steering torque greater than the reaction torque of the reaction force motor.
Innovation Solution
A steer-by-wire steering device is designed with a steering shaft connected to a torsion bar and a first rotor, which is connected to a motor and a second rotor. The second rotor has a stopper that limits its rotation angle, preventing further rotation of the steering shaft when the reaction force motor reaches its maximum output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a steer-by-wire steering device is used to eliminate mechanical connection between steering shaft and wheels, then fuel efficiency is improved and assembly complexity is reduced, but steering feel deteriorates due to indefinite rotation of steering shaft
Solution Approach 1:
A reaction force motor is introduced as an intermediary between the steering shaft and the driver's hand. This motor generates artificial reaction torque to simulate the mechanical feedback that would normally be provided by a mechanical connection to the wheels, thereby improving steering feel without requiring physical mechanical linkage.
Solution Approach 2:
The patent replaces the traditional mechanical connection system with an electromechanical system. Instead of direct mechanical linkage between steering shaft and wheels, an motor-driven reaction force generation system is used to provide the necessary feedback, eliminating mechanical parts while maintaining operational feel.
2Ease of operation
If reaction force motor is used to provide steering feedback, then steering feel is improved, but when driver applies torque greater than motor's reaction torque, steering shaft can still rotate indefinitely
Solution Approach 1:
A stopper mechanism is pre-positioned to limit the rotation range of the steering shaft before indefinite rotation can occur. This preliminary mechanical constraint ensures that even when the reaction force motor cannot provide sufficient counter-torque, the steering shaft cannot rotate beyond a predetermined angle, maintaining system stability.
Solution Approach 2:
The steering system is segmented into multiple functional components: the reaction force motor for providing feedback torque, and a separate stopper mechanism for limiting rotation. This segmentation allows each component to perform its specific function independently, ensuring both steering feel and rotation limitation are achieved.
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
This solution provides a better steering feel by mechanically stopping the steering shaft from rotating when the driver applies excessive steering torque, enhancing driver feedback and control.
Implementation Method 1
a steering shaft connected with one end of a torsion bar
Implementation Method 2
having a first gear part formed on an outer circumferential surface thereof, a first rotor rotatably coupled inside a housing to be connected with a motor, connected with other end of the torsion bar, and having a hollow receiving part at one side thereof, the hollow receiving part axially extending and having a second gear part formed on an inner circumferential surface thereof
Data Source
AI summary
According to embodiments of the present invention, when a driver applies steering torque greater than the reaction torque of a reaction motor to a steering shaft, the steering shaft is mechanically prevented from rotating any more, and thus the driver's steering feel can be improved.