Vehicle Brake Control Apparatus for Torque Fluctuation
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Solution Overview
Problem
Existing vehicle brake control devices face challenges in effectively suppressing braking torque fluctuations caused by disc rotor thickness variations, leading to vibrations and increased power consumption due to complex control over electric motors.
Innovation Solution
A vehicle brake control device that includes operation amount acquisition, braking means, pressing-force acquisition, and control means to calculate a target energization amount based on operation and pressing force, with a limit value to suppress pressing force fluctuations, ensuring stable control by differentiating between operational and noise components of pressing force changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is executed based on actual pressing force to suppress braking torque fluctuation, then braking torque stability is improved, but system complexity and power consumption increase
Solution Approach 1:
The patent extracts only the necessary component of pressing force information (temporal change amount) for control purposes, rather than using the complete pressing force signal. This selective extraction simplifies the control system while maintaining the ability to suppress braking torque fluctuations caused by disc rotor thickness variations.
Solution Approach 2:
The pressing force signal is segmented into different components: the temporal change amount (dFba/dt) which contains information about disc rotor thickness variation, and the steady-state component. The control system processes only the temporal change amount to generate the target energization amount, reducing computational complexity while maintaining control effectiveness.
2Reliability
If the electric motor is controlled to follow pressing force fluctuations without delay, then braking torque fluctuation is reduced, but control complexity increases
Solution Approach 1:
The patent replaces complex mechanical feedback control with a simplified computational approach. Instead of using complex feedback control algorithms to track pressing force fluctuations, the system calculates the temporal change amount of pressing force and uses this derivative information to directly determine the target energization amount, achieving the same effect with simpler computation.
3Object-affected harmful factors
If the pressing force fluctuation is suppressed actively, then vibration is reduced, but power consumption increases
Solution Approach 1:
The patent applies partial action by using only the temporal change amount of pressing force (dFba/dt) rather than the complete pressing force signal for control. This partial use of information is sufficient to suppress vibrations caused by disc rotor thickness variation while minimizing the energization adjustments needed, thereby reducing power consumption compared to full feedback control.
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
The solution effectively reduces braking torque fluctuations and stabilizes control over the electric motor, ensuring responsiveness and efficient energy use by distinguishing between operational and noise-induced pressing force changes, thereby suppressing vibrations and power consumption.
Implementation Method 1
braking means for pressing a friction member against a rotating member through intermediation of an electric motor to generate a braking torque
Implementation Method 2
friction member (MSB) against a rotating member (KTB) to generate a braking torque
Data Source
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AI summary
Based on a difference between a target value and an actual value of a force of a friction member to press a brake disc, feedback control over the pressing force is executed. As the actual value, a detection value (Fba) of the pressing force itself is not used, but a "limit pressing force (Fbs) obtained by placing a limitation on a temporal change amount of the Fba based on of a limit value (Lmt)" is used. The limit value (Lmt) is set based on an electric motor speed (dMkt, dMka), a wheel speed (Vwa), and a temporal change amount (ΔTmp) of a temperature of the friction member. The Lmt is set so as to increase as the dMkt (dMka) increases and the temporal change amount (ΔTmp) of the temperature increases, and so as to also increase as the wheel speed (Vwa) decreases. Thus, in a vehicle brake control device configured to generate a braking torque by an electric motor, even when a rotating member (brake disc) is deformed, braking torque control can be appropriately executed without accelerating a fluctuation of a braking torque on the wheel.