Steering Wheel Locking via Motor Phase Shorting in SBW
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Solution Overview
Problem
In Steer-By-Wire (SBW) systems, the steering wheel freewheels when the ignition switch is turned off, posing a risk of injury to the driver as there is no mechanical connection to lock the wheel, and existing solutions are costly and inefficient.
Innovation Solution
A steering wheel locking control apparatus and method that uses a power supply switch and a switch unit connected to a motor to create a closed circuit, applying reaction force torque to lock the wheel through counter electromotive force when the ignition is off, preventing freewheeling and rapid steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical locking connection is used in traditional steering systems, then the steering wheel is locked when ignition is off, but the SBW system removes this mechanical connection to increase layout freedom and fuel efficiency
Solution Approach 1:
The patent replaces the mechanical locking connection with an electrical control system. A power supply switch and switch unit create a closed circuit that applies reaction force torque through the motor to lock the steering wheel, eliminating the need for mechanical connection while maintaining the locking function.
Solution Approach 2:
The patent changes the operational state of the power supply switch based on the ignition signal parameter. When ignition is off, the power supply switch turns on, activating the switch unit to create a closed circuit and apply locking torque, thus adapting the system state according to ignition conditions.
2Reliability
If the power supply switch and switch unit are activated to lock the steering wheel, then driver safety is improved, but electrical circuit complexity increases
Solution Approach 1:
The patent merges the power supply switch and switch unit into a coordinated electrical control system that shares common circuitry and control logic. The switch unit includes switches electrically connected to motor phases, and both components work together through a unified control mechanism triggered by the ignition signal, reducing overall system complexity.
3Reliability
If the switch unit creates a closed circuit to apply reaction force torque, then the steering wheel is effectively locked, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by activating the power supply switch and switch unit only when the ignition is off, rather than continuously. The system transitions between locked and unlocked states based on ignition conditions, consuming energy only when locking is required, thus reducing overall energy consumption while maintaining effective locking when needed.
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
Effectively prevents the steering wheel from freewheeling, reducing the risk of driver injury and lowering manufacturing costs compared to mechanical locking systems, while maintaining the benefits of the SBW system's layout flexibility and fuel efficiency.
Implementation Method 1
The switch unit may lock the steering wheel by applying reaction force torque to the steering wheel, the reaction force torque being caused by a counter electromotive force generated by the motor in the closed circuit
Data Source
AI summary
A steering wheel locking control apparatus may include: a power supply switch configured to receive power from a battery when an ignition switch of a vehicle is turned off; and a switch unit connected to a motor, turned on when power is received through the power supply switch, and configured to lock a steering wheel through a closed circuit formed by shorting phases of the motor.