System for estimating brake-fluid pressure

A motor vehicle, comprising:

• a source of a fluid pressure;
• a brake actuator actuated by the fluid pressure;
• and
• a brake control system comprising:
• a pressure control valve which adjusts the fluid pressure within the brake actuator, the pressure control valve selectively carrying out operation for supplying fluid to the brake actuator, operation for discharging fluid from the brake actuator, and operation for retaining fluid in the brake actuator;
• and
• an ECU which controls the pressure control valve, the ECU providing to the pressure control valve a first control signal including a duty-ratio signal comprising a valve opening drive signal as a supplying operation signal and a retaining operation signal upon the supplying operation of the pressure control valve, the ECU comprising an estimate part which is so constructed as to:
• totalize an influent amount of fluid in the brake actuator in accordance with an output time of the valve opening drive signal of the first control signal and a supply amount per unit time of fluid in the pressure control valve;
• estimate an amount of fluid in the brake actuator in accordance with the influent amount as totalized;
• estimate a value of the fluid pressure within the brake actuator in accordance with the amount of fluid as estimated;
• and
• carry out correction for obtaining a supply amount of fluid in the brake actuator when a time of the retaining operation performed by the first control signal is smaller than a predetermined value, the correction being performed by adding a correction value corresponding to the time to the output time of the valve opening drive signal of the first control signal.

A method of controlling a braking device for a motor vehicle, the braking device comprising:

• a brake actuator actuated by a fluid pressure;
• and
• a pressure control valve which adjusts the fluid pressure within the brake actuator, the pressure control valve selectively carrying out operation for supplying fluid to the brake actuator, operation for discharging fluid from the brake actuator, and operation for retaining fluid in the brake actuator,
• the method comprising:
• providing to the pressure control valve a first control signal including a duty-ratio signal comprising a valve opening drive signal as a supplying operation signal and a retaining operation signal upon the supplying operation of the pressure control valve;
• totalizing an influent amount of fluid in the brake actuator in accordance with an output time of the valve opening drive signal of the first control signal and a supply amount per unit time of fluid in the pressure control valve;
• estimating an amount of fluid in the brake actuator in accordance with the influent amount as totalized;
• estimating a value of the fluid pressure within the brake actuator in accordance with the amount of fluid as estimated;
• and
• carrying out correction for obtaining a supply amount of fluid in the brake actuator when a time of the retaining operation performed by the first control signal is smaller than a predetermined value, the correction being performed by adding a correction value corresponding to the time to the output time of the valve opening drive signal of the first control signal.