Brake Hydraulic Pressure Control on Split Roads
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Solution Overview
Problem
Existing vehicle brake hydraulic pressure control systems experience instability and driver discomfort due to varying permissible differential pressures during antilock braking control, especially on split roads with differing friction coefficients, as the timing of pressure increase depends on brake operation speed.
Innovation Solution
A vehicle brake hydraulic pressure control apparatus with a hydraulic pressure adjusting unit, split road determining section, and differential pressure control section that sets a permissible differential pressure based on a predetermined time period rather than brake operation speed, ensuring stable control and reducing driver discomfort by maintaining consistent pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the permissible differential pressure is increased according to the drop amount of wheel speed on the high coefficient-of-friction side, then the differential pressure control effectiveness is improved, but the timing variation causes driver physical disorder feeling
Solution Approach 1:
The patent changes the control parameter from wheel speed drop amount to elapsed time since antilock braking control start. This parameter substitution eliminates the timing variation caused by different brake operation speeds while maintaining differential pressure control effectiveness, thereby resolving the contradiction between control reliability and driver comfort
Solution Approach 2:
The patent implements dynamic adjustment of permissible differential pressure based on elapsed time stages. The control system transitions from a static threshold-based approach to a dynamic time-based approach, allowing the permissible differential pressure to increase progressively as time elapses, which maintains control effectiveness while ensuring consistent timing independent of brake operation speed
2Manufacturing precision
If the permissible differential pressure is set to increase based on wheel speed drop amount, then initial stage suppression is achieved, but timing depends on brake operation speed causing inconsistency
Solution Approach 1:
The patent establishes predetermined time periods and corresponding permissible differential pressure values in advance. By pre-defining the control strategy based on elapsed time rather than real-time wheel speed variations, the system achieves consistent timing for differential pressure adjustment regardless of brake operation speed, eliminating time variation while maintaining control precision
Data Source
AI summary
A vehicle brake hydraulic pressure control apparatus includes a hydraulic pressure adjusting unit, a split road determining section, a differential pressure control section, and a hydraulic pressure adjusting and driving section. The hydraulic pressure adjusting unit individually adjusts brake fluid pressures acting on wheel brakes for wheels. The split road determining section determines whether road surfaces which the wheels are in contact with constitute a split road. In a state where the split road determining section determines during execution of antilock braking control that the road surfaces constitute the split road, the differential pressure control section determines command pressures for the wheel brakes so that differential pressures between the brake fluid pressures of the right and left wheel brakes are equal to or less than a permissible differential pressure. The hydraulic pressure adjusting and driving section controls the hydraulic pressure adjusting unit based on the determined command pressures.