Brake Pressure Control Switching With Seal Friction Compensation
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Solution Overview
Problem
Existing vehicle braking control devices face challenges in smoothly switching from a two-system pressure adjustment to a one-system pressure adjustment, which is necessary for efficient braking control.
Innovation Solution
A vehicle braking control device that adjusts liquid pressures of front and rear wheel cylinders based on a braking required amount, using an applying unit with a cylinder, supply, and servo chambers, and a pressure adjustment unit that electrically adjusts servo pressures to control the liquid pressures, with sensors to detect supply pressures and a controller to select between two-system and one-system pressure adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching from two-system pressure adjustment to one-system pressure adjustment is implemented, then braking control efficiency is improved, but pressure discontinuity and roughness occur during switching
Solution Approach 1:
The controller preliminarily calculates the common target pressure considering seal member friction before switching to one-system pressure adjustment, ensuring that the pressure transition is smooth and continuous. This preliminary calculation prevents pressure discontinuity by preparing the appropriate pressure value in advance.
Solution Approach 2:
The system changes the pressure control parameters by transitioning from independent front and rear wheel pressure control to unified common target pressure control. The controller adjusts the servo pressures P1 and P2 to be equal, and calculates the common target pressure Px by adding a predetermined pressure ps to the target pressure Ptf, thereby achieving smooth switching between control modes.
2Measurement precision
If seal member friction is not compensated during one-system pressure adjustment, then pressure control accuracy deteriorates, but system complexity increases if compensation is added
Solution Approach 1:
The controller compensates for seal member friction by adding a predetermined pressure ps to the target pressure Ptf to calculate the common target pressure Px. This parameter adjustment ensures accurate pressure control without requiring additional hardware, maintaining simplicity while improving precision.
Solution Approach 2:
The system uses the front wheel target pressure Ptf as a reference and creates a compensated common target pressure Px by adding the predetermined pressure ps. This copying approach allows the same pressure control logic to be applied to both front and rear wheels while accounting for friction differences.
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 device enables smooth switching between two-system and one-system pressure adjustments, ensuring effective braking control and minimizing disruptions in wheel pressure during the switching process.
Implementation Method 1
a predetermined pressure ps is added to the common target pressure Px of the one-system pressure adjustment so as to compensate for a friction resistance of the seal member SL
Data Source
AI summary
A vehicle braking control device includes supply and servo chambers sealed by a seal member, a pressure adjustment unit that adjusts front wheel pressure by supplying a first servo pressure to the servo chamber and outputs front wheel supply pressure from the supply chamber to a front wheel cylinder, and adjusts rear wheel pressure by outputting a second servo pressure to a rear wheel cylinder as rear wheel supply pressure, front/rear wheel supply pressure sensors that detect the front/rear wheel supply pressures respectively, and a controller that selects any one of a two-system pressure adjustment for individually adjusting the first and second servo pressures, and a one-system pressure adjustment for adjusting the first and second servo pressures to be the same. The controller individually calculates front/rear wheel target pressures and causes the front/rear wheel supply pressures to coincide with the front/rear wheel target pressures in the two-system pressure adjustment