Brake Control Device Differential Pressure Compensation
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Solution Overview
Problem
The existing brake control systems face challenges in accurately controlling fluid pressure in wheel cylinders when the differential pressure adjustment valve is not driven, leading to increased fluid pressure due to unintended differential pressure generation, which affects controllability.
Innovation Solution
A brake control device that includes a wheel fluid pressure derivation unit, passing-flow-rate derivation unit, differential pressure derivation unit, and a holding valve operating unit to calculate and adjust the differential pressure between the master cylinder and wheel cylinder sides, allowing for precise control of the holding valve's opening degree to manage fluid pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the differential pressure adjustment valve is not driven and the brake fluid is discharged from the pump, then the brake fluid discharge function is achieved, but unintended differential pressure is generated between master cylinder side and wheel cylinder side, causing fluid pressure in wheel cylinders to exceed command value
Solution Approach 1:
The control device calculates the actual differential pressure generated by the differential pressure adjustment valve based on pump discharge flow rate and holding valve passing flow rate, then uses this feedback information to adjust the holding valve opening degree, thereby compensating for the unintended pressure increase and achieving accurate wheel cylinder fluid pressure control
Solution Approach 2:
The patent replaces direct mechanical pressure measurement with a calculation-based approach, deriving differential pressure values through mathematical computation from flow rate data, and uses this computational information to control the holding valve, substituting mechanical feedback with electronic control
2Device complexity
If the command opening degree for the holding valve is derived under the assumption that differential pressure is not generated, then the control calculation is simplified, but the fluid pressure in wheel cylinders becomes higher than command value
Solution Approach 1:
The patent changes the control parameter from assumed differential pressure (zero) to calculated actual differential pressure, using flow rate data to compute the real differential pressure value, thereby improving pressure control precision without significantly increasing system complexity
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
Enhances controllability of fluid pressure in wheel cylinders by accurately calculating and accounting for differential pressure, preventing excessive pressure increases and improving braking performance.
Implementation Method 1
a pump for discharging a brake fluid between the differential pressure adjustment valve and the holding valve
Implementation Method 2
a differential pressure adjustment valve arranged on a fluid line for connecting a master cylinder with wheel cylinders
Data Source
AI summary
A control device is provided with a flow rate derivation part for deriving a pressure-holding-valve flow rate on the basis of a pressure command value and a previous pressure command value; a differential pressure derivation part for deriving a differential-pressure-valve differential pressure value so that the differential-pressure-valve differential pressure value increases with an increase in the difference obtained by subtracting the pressure-holding-valve flow rate from a pump-discharge flow rate; and a pressure-holding-valve processing part for performing an aperture derivation process to derive a command aperture so that the command aperture decreases with an increase in the difference obtained by subtracting the pressure command value from the sum of an pressure value and the differential-pressure-valve differential pressure value, and driving a holding pressure valve at the command aperture.