Electric Parking Brake Current Window for Stable Clamping Force
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Solution Overview
Problem
Existing electric parking brake systems require long-term data measurement of current and voltage, which can be influenced by load fluctuations during idle running, leading to complex calculations and potential errors.
Innovation Solution
The system includes a current detection unit and a brake control device that calculates the motor stop current based on the current change amount from the peak current to a predetermined time, and optionally uses a low-pass filter to remove noise and determine the motor stop current based on the LPF current change during a specific period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data measurement is performed for a long time from current change stage to idle running stage, then the motor constant can be determined, but the measurement is influenced by load fluctuation during idle running and complicated calculation becomes necessary
Solution Approach 1:
The patent extracts only the essential information needed for motor constant determination by focusing measurement on the current change stage only, excluding the idle running stage. This is achieved by detecting the gradient of current change during the current change stage and using this gradient information to calculate the motor constant, thereby eliminating the need for long-term measurement through idle running stage and avoiding load fluctuation influences.
Solution Approach 2:
The patent segments the braking process into distinct stages (current change stage and idle running stage) and performs measurement only during the current change stage. By dividing the process and selecting the optimal measurement window, the system avoids the complications of measuring through the entire process including the idle running stage with its load fluctuations.
2Measurement precision
If data measurement is performed for a long time from current change stage to idle running stage, then the motor constant can be determined, but the measurement time is extended
Solution Approach 1:
The patent extracts only the essential information needed for motor constant determination by focusing measurement on the current change stage only, excluding the idle running stage. This is achieved by detecting the gradient of current change during the current change stage and using this gradient information to calculate the motor constant, thereby eliminating the need for long-term measurement through idle running and reducing measurement time.
Solution Approach 2:
The patent skips the idle running stage for measurement purposes and rushes through to obtain the motor constant using only the current change stage data. By skipping the time-consuming idle running measurement phase and directly using the gradient information from the current change stage, the system significantly reduces measurement time while maintaining accuracy.
3Measurement precision
If low pass filter is used to remove noise of motor current, then the measurement accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent introduces a low pass filter as an intermediary component between the current detection unit and the control device. This filter mediates the signal processing by removing high-frequency noise from the motor current signal while allowing the essential current change information to pass through, thereby improving measurement accuracy without significantly increasing system complexity.
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 approach allows for the determination of an appropriate clamping force without excessive complexity, reducing the influence of load fluctuations and simplifying the calculation process, thereby providing a reliable and efficient electric parking brake system.
Implementation Method 1
a low pass filter configured to remove noise of the motor current
Implementation Method 2
an electric motor configured to impart a thrust to the pressing member
Implementation Method 3
a pressing member that is configured to be pressed to the rotary member
Data Source
AI summary
Provided fire an electric parking brake device and an electric parking brake control method that can apply an appropriate clamping force by accelerating data measurement and by suppressing influence of load fluctuation during idle running. For this end, the electric parking brake device of the present invention includes: a disc rotor; brake pads that are pressed to the disc rotor; an electric motor that imparts a thrust to the brake pads; a current detection unit that detects a motor current of the electric motor; and a brake control device that controls the electric motor 8 based on the motor current. The brake control device controls the electric motor 8 based on a current change amount of an electric current during a period from a point of time that the motor current becomes a peak current to a predetermined point of time.