Vehicle Brake Hydraulic Pressure Control on Split Roads
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Solution Overview
Problem
Existing vehicle brake hydraulic pressure control systems fail to adequately stabilize vehicle attitude on split roads with differing friction coefficients, leading to instability and unsuitable brake hydraulic pressure control.
Innovation Solution
A vehicle brake hydraulic pressure control device with a split road deciding unit, hydraulic pressure controlling unit, and vehicle state deciding unit, which adjusts brake hydraulic pressure differentials based on road conditions and vehicle stability, using multiple control methods and thresholds to manage brake pressure on high-μ and low-μ road sides, and dynamically adjusts the upper limit of hydraulic pressure based on yaw rate deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake hydraulic pressure on high-μ road side is limited using acceptable differential pressure, then differential pressure between right and left wheel brakes is controlled, but vehicle attitude control is insufficient when vehicle is in unstable state
Solution Approach 1:
The patent implements dynamic adjustment of brake hydraulic pressure control strategy based on real-time vehicle stability assessment. The control system transitions from a static acceptable differential pressure approach to a dynamic control mode when vehicle instability is detected through yaw rate deviation thresholds, enabling adaptive response to changing vehicle states
Solution Approach 2:
The system continuously monitors actual yaw rate and compares it with target yaw rate to assess vehicle stability. This feedback mechanism triggers additional pressure decrease actions when instability is detected, creating a closed-loop control system that responds to vehicle attitude deviations
2Stability of the object's composition
If brake hydraulic pressure on high-μ road side is decreased to control vehicle attitude, then vehicle stability improves, but sudden pressure fluctuations may occur
Solution Approach 1:
The system applies preliminary counter-actions by decreasing brake hydraulic pressure on the high-μ side when yaw rate deviation exceeds thresholds, preventing vehicle instability before it fully develops. This proactive control approach counteracts potential instability trends
3Ease of operation
If acceptable differential pressure is used to control brake pressure differential, then basic split road braking is achieved, but enhanced vehicle attitude control during instability is insufficient
Solution Approach 1:
The control system automatically assesses vehicle stability using onboard sensors (yaw rate sensor, steering angle sensor) and autonomously adjusts brake pressure without requiring driver intervention. The system serves itself by detecting instability conditions and implementing corrective pressure adjustments
Data Source
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AI summary
The hydraulic pressure controlling unit is capable of execute a first control, a second control, and a third control. The third control is configured to be started under condition that during the second control, an anti-lock brake control on the wheel brake on the high-µ road side is started, the acceptable differential pressure is equal to or larger than a first threshold, or a steering angle of a steering is equal to or larger than a second threshold. During the third control, the hydraulic pressure controlling unit is configured to decrease the hydraulic pressure of the wheel brake on the high-µ road side if the vehicle state deciding unit decides that the vehicle is in an unstable state.