Shift Switching Device Fault Detection Without Sensors
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Solution Overview
Problem
Shift-by-wire type shift switching devices for automatic transmissions face challenges in distinguishing between break and short-circuit faults in electric motors, leading to inability to switch shift ranges due to fear of over-current issues, and existing fault detection methods require additional sensors, increasing cost and complexity.
Innovation Solution
A method that determines break/short-circuit faults without additional sensors by using open-loop control of the electric motor with a normal phase, where activation indicates a break fault and lack of activation indicates a short-circuit fault, allowing for continued shift range switching in case of a break fault and preventing overcurrent in case of a short-circuit fault.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fault detection is performed using additional sensors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The electric motor performs self-diagnosis by monitoring its own operational state. The control unit detects faults by analyzing the motor's response to control signals without requiring external sensors, enabling the system to serve its own diagnostic needs and eliminating additional measurement devices
Solution Approach 2:
The patent replaces physical sensor-based detection with an electrical/control-based diagnostic system. By using the control unit to monitor motor response characteristics and detect abnormalities through electrical signal analysis, the mechanical/sensor-based detection method is substituted with a software/control-based approach
2Reliability
If current supply is stopped to prevent over-current, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The patent segments the three-phase power supply to the motor, allowing selective supply to individual phases based on fault detection. When a fault is detected in one phase, current supply is maintained to the other healthy phases, enabling the motor to continue operating with reduced functionality rather than complete shutdown
Solution Approach 2:
The control system dynamically adjusts current supply to motor phases based on real-time fault detection. The system transitions from static all-or-nothing power supply to dynamic selective phase activation, allowing the motor to adapt its operation to the detected fault condition and maintain functionality when possible
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
Enables determination of fault type without additional sensors, allowing for continued shift range switching in case of a break fault and preventing overcurrent in case of a short-circuit fault, thus enhancing reliability and reducing costs.
Implementation Method 1
a controller determines a fault in a current supply line in each phase of the electric motor on a phase-by-phase basis, executes open-loop control of the electric motor in a normal phase, and determines a fault in a current supply line by detecting an activation state of the electric motor
Data Source
AI summary
A shift-by-wire shift switching device and shift switching method that switch a shift range of an automatic transmission using an electric motor. The shift switching device includes a controller that determines whether a fault has occurred in a current supply line of each phase of the electric motor on a phase-by-phase basis, executes an open-loop control of the electric motor using only the phases in which it has been determined that a fault has not occurred, and determines whether a fault has occurred in the current supply line by detecting an activation state of the electric motor when the open-loop control of the electric motor is executed. Therefore, it is possible to determine whether a fault in the motor is a short-circuit fault or a break fault, without addition of a part such as a short-circuit detection sensor.