Electric Brake Motor Current Sensing for Fast Pad Contact Detection
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Solution Overview
Problem
Existing methods for detecting the contact between brake pads and a disk rotor in electric brake apparatuses suffer from insufficient accuracy and prolonged detection times due to small changes in current with respect to thrust force.
Innovation Solution
An electric brake apparatus with a control device that detects contact between the braking member and target member based on changes in current when power is supplied to specific driving circuits of a multi-phase electric motor, utilizing a control device to monitor current variations and set a threshold value for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing detection method using motor current pattern storage and subtraction is used, then the detection process can be implemented, but the detection accuracy is insufficient and detection time is prolonged due to small current change amount
Solution Approach 1:
The invention changes the operating parameter of the motor by supplying power to only a part of the driving circuits (e.g., one phase or one pole) instead of all circuits. This parameter change causes a significant current change when the braking member contacts the braking target member, enabling accurate and rapid detection through threshold comparison.
2Measurement precision
If power is supplied to all driving circuits, then the motor operates normally, but the current change amount upon contact is small making detection difficult
Solution Approach 1:
The invention applies partial action by supplying power to only a portion of the driving circuits (one phase or one pole) during the detection process. This partial power supply creates a larger current change signal upon contact, improving detection accuracy without requiring full motor power.
3Measurement precision
If the detection threshold is set low to improve detection sensitivity, then contact can be detected earlier, but false detection increases due to current ripple and noise
Solution Approach 1:
The invention uses feedback by monitoring the actual current change and comparing it with a predetermined threshold value. The system adjusts the detection decision based on whether the current change exceeds the threshold, enabling reliable contact detection that distinguishes true contact signals from noise and current ripple.
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
Enhances the accuracy and speed of detecting the contact between brake pads and the disk rotor, reducing clearance variation and ensuring optimal brake responsiveness.
Implementation Method 1
an electric motor (40) including a plurality of driving circuits (120, 122), an electric mechanism configured to press a braking member (2, 3) against a braking target member (D) based on driving of the electric motor (40), and a control device (118) configured to control driving of the electric motor (40). The control device (118) detects contact between the braking member (2, 3) and the braking target member (D) based on a change in a current of the electric motor (40) when power is supplied to a part of the driving circuits (120, 122) among the plurality of driving circuits (120, 122).
Data Source
AI summary
An electric brake apparatus includes an electric motor including driving circuits, a brake mechanism configured to press a braking member against a braking target member based on driving of the electric motor, and a control device configured to control the driving of the electric motor. The control device is configured to detect contact between the braking member and the braking target member based on a change in a current of the electric motor when power is supplied to a part of the driving circuits. A change amount of the current between before and after the braking member and the braking target member contact each other is larger when power is supplied to the part of the driving circuits than when power is supplied to all of the driving circuits.