Vehicle Brake Fluid Pressure Control Using Lock Fluid Pressure
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Solution Overview
Problem
Existing vehicle brake fluid pressure control systems face challenges in stabilizing allowable differential pressures between wheel brakes, leading to hunting issues due to fluid pressure changes during anti-lock brake control, and struggle to accurately match road surface friction coefficients.
Innovation Solution
A vehicle brake fluid pressure control apparatus that adjusts brake fluid pressures for front and rear wheels independently, using a fluid pressure acquiring unit to determine the lock fluid pressure and setting allowable differential pressures based on this lock fluid pressure, road surface friction coefficient, and estimated vehicle body deceleration, while incorporating judges for split and low-friction roads to prevent instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fluid pressure of the wheel brake of the coaxial wheel is used as a component corresponding to the friction coefficient of the road surface, then the allowable differential pressure can be set, but hunting occurs due to fluid pressure change during anti-lock brake control and stable allowable differential pressures cannot be obtained
Solution Approach 1:
The patent introduces an intermediary parameter called 'lock fluid pressure' which represents the fluid pressure at which pressure decrease by anti-lock brake control is started. This lock fluid pressure serves as a mediator between the actual brake fluid pressure and the allowable differential pressure setting, filtering out the harmful fluctuations while preserving the essential information about road surface friction characteristics.
Solution Approach 2:
The system implements feedback by continuously monitoring the lock fluid pressure of the coaxial wheel and using this information to dynamically adjust the allowable differential pressure settings. The fluid pressure acquiring means acquires the lock fluid pressure, and this feedback loop ensures that the allowable differential pressure reflects the actual road conditions while remaining stable.
2Reliability
If anti-lock brake control is performed independently for left and right coaxial wheels, then wheel lock prevention is achieved, but differential pressure control complexity increases
Solution Approach 1:
The patent segments the brake control system into independent control units for left and right coaxial wheels, allowing each wheel to be controlled independently based on its own lock fluid pressure characteristics. This segmentation enables precise wheel lock prevention while the systematic approach to differential pressure control manages the complexity through modular design.
Data Source
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AI summary
A vehicle brake fluid pressure control apparatus controls operations of a fluid pressure adjusting unit capable of performing adjustment of individually increasing and decreasing brake fluid pressures acting respectively on wheel brakes for front wheels and wheel brakes for rear wheels to be within allowable differential pressures allowable between the brake fluid pressures of the wheel brakes for the left and right coaxial front wheels and the left and right coaxial rear wheels. In the apparatus, a fluid pressure acquiring device acquires a lock fluid pressure of a wheel brake of a wheel coaxial with a wheel being a control target, the lock fluid pressure being a fluid pressure at which pressure decrease by an anti-lock brake control is started. An allowable differential pressure setting device sets the allowable differential pressures matching a road surface friction coefficient on the basis of at least the lock fluid pressure obtained by the fluid pressure acquiring device. The allowable differential pressures stably matching a friction coefficient of a road surface can be thereby obtained.