Brake System Dynamic Target Force Adjustment
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Solution Overview
Problem
Conventional disk brake systems with electric parking brake functions face issues of excessive or insufficient braking force due to static corrections in target current values, leading to inconsistent braking performance when hydraulic pressure changes during parking brake engagement.
Innovation Solution
A brake system with a controller that dynamically adjusts the target pressing force based on changes in hydraulic pressure after initiating the electric mechanism, using a combination of wheel cylinder and master cylinder pressure sensors to ensure appropriate braking force, thereby preventing excessive or insufficient braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target current value is corrected based on initial hydraulic pressure when starting the parking brake, then the braking force is improved initially, but the braking force becomes excessive or insufficient when hydraulic pressure changes during operation
Solution Approach 1:
The patent applies dynamics by transitioning from a static target current value correction (based only on initial hydraulic pressure) to a dynamic correction mechanism that continuously updates the target current value in response to real-time hydraulic pressure changes. The control unit monitors hydraulic pressure throughout the parking brake operation and adjusts the target current value accordingly, ensuring the braking force remains appropriate even as hydraulic pressure fluctuates during vehicle operation.
Solution Approach 2:
The patent implements feedback by creating a closed-loop control system where the control unit continuously monitors hydraulic pressure and uses this information to adjust the target current value. The detected hydraulic pressure is fed back to the control unit, which then modifies the target current value to maintain appropriate braking force. This feedback mechanism resolves the contradiction by making the system adaptive to changing conditions while maintaining reliable braking performance.
2Ease of operation
If the electric motor is driven with hydraulic pressure already exerted on the piston, then the parking brake can be applied during braking operations, but stopping the motor based on the same current threshold leads to excessive braking force
Solution Approach 1:
The patent applies parameter changes by modifying the target current value parameter based on the detected hydraulic pressure level. When hydraulic pressure is present during parking brake application, the control unit adjusts the target current value to a lower threshold, accounting for the assisting hydraulic force. This ensures the electric motor stops at the appropriate point, preventing excessive braking force while allowing the parking brake to function during braking operations.
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 system effectively maintains consistent braking force by adjusting the target current value in real-time with hydraulic pressure changes, preventing both excessive and insufficient braking forces during parking brake engagement.
Implementation Method 1
a pressure sensor that detects a pressure in the brake apparatus
Implementation Method 2
a brake apparatus including an electric mechanism and a hydraulic source and configured to keep a vehicle braked by the electric mechanism
Implementation Method 3
brake the vehicle by supply of a hydraulic pressure from the hydraulic source
Data Source
AI summary
A brake system includes a brake apparatus. This brake apparatus is configured to keep a vehicle braked by an electric mechanism in response to a parking brake request signal, and brake the vehicle by supply of a hydraulic pressure from a hydraulic source in response to an operation performed on a brake pedal. The brake system further includes a controller configured to drive the electric mechanism until a target pressing force is acquired to establish a brake holding state in response to the parking brake request signal. The controller is configured to change the target pressing force according to a change in a hydraulic pressure in the brake apparatus after starting driving the electric mechanism in response to the parking brake request signal.