Brake Control Valve Pressure Fluctuation Management
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Solution Overview
Problem
Existing antiskid brake apparatuses experience degradation in controllability due to fluctuations in hydraulic pressure caused by the opening and closing of the antiskid control valve, affecting the braking force applied to wheels.
Innovation Solution
A brake control apparatus with a common control valve upstream of retention valves, which minimizes pressure fluctuations by adjusting the command value and control gain based on the capacity changes caused by the actuation of retention valves, using feedback and feedforward control laws to improve controllability and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the retention valves are actuated to restrain wheel slip, then the wheel slip is restrained, but the primary-side pressure of the retention valves fluctuates due to capacity changes
Solution Approach 1:
The control portion monitors the actual primary-side pressure of the retention valves and compares it with the target pressure, then adjusts the command value for the common control valve based on the pressure difference. This feedback mechanism compensates for pressure fluctuations caused by retention valve actuation, maintaining stable primary-side pressure while effectively restraining wheel slip.
Solution Approach 2:
The control portion predicts capacity changes based on the actuation state of retention valves and adjusts the command value for the common control valve in advance. By performing preliminary adjustment before pressure fluctuations occur, the system prevents pressure instability rather than merely reacting to it, thereby maintaining stable primary-side pressure during wheel slip restraint operations.
2Speed
If the control gain is increased to improve responsiveness, then the responsiveness is improved, but the pressure fluctuations are amplified
Solution Approach 1:
The control portion dynamically adjusts the command value for the common control valve based on real-time capacity changes detected from retention valve actuation. By making the control parameter adaptive rather than fixed, the system achieves high responsiveness when needed while automatically damping pressure fluctuations, thus improving responsiveness without amplifying instability.
3Device complexity
If a common control valve is used upstream of retention valves, then the device complexity is reduced, but the controllability is degraded due to pressure fluctuations
Solution Approach 1:
The control portion acts as an intermediary between the common control valve and the retention valves. It processes information about capacity changes from retention valve actuation and generates adjusted command values for the common control valve. This intermediary control function compensates for the inherent pressure fluctuations in the simplified valve system, maintaining good controllability of wheel cylinder pressure despite using a common control valve upstream.
Data Source
AI summary
The invention provides a brake control apparatus that improves the controllability of a vehicle in the control for restraining slip of the wheels. The brake control apparatus includes: wheel cylinders that apply braking force individually to wheels by supplying a working fluid; retention valves that are provided respectively upstream of the wheel cylinders and that are opened and closed so as to restrain slip of the wheels; a common control valve provided upstream of the retention valves to supply the working fluid to the wheel cylinders; and a control portion that controls the common control valve by different control laws to restrain fluctuations in pressure on a primary side of the retention valves caused by fluctuations in a capacity to which the working fluid from the common control valve is supplied, by opening or closing of the retention valves.