Hydraulic brake system for vehicle

A hydraulic brake system for a vehicle, comprising:

• a braking operation member operable by a driver;
• a brake device provided on a wheel and configured to generate a braking force according to a pressure supplied to the brake device,
• a liquid-pressure source device including:
• an electromagnetic pressure-increase linear valve configured to increase a pressure of working fluid in accordance with an electric power supplied to the pressure-increase linear valve;
• and an electromagnetic pressure-reduce linear valve configured to reduce the pressure of the working fluid in accordance with an electric power supplied to the pressure-reduce linear valve, the liquid-pressure source device being configured to supply the working fluid whose pressure has been regulated by the pressure-increase linear valve and the pressure-reduce linear valve;
• an ABS valve device disposed between the liquid-pressure source device and the brake device;
• and
• a controller configured to control the electric power supplied to the pressure-increase linear valve to control the operation of the pressure-increase linear valve and configured to control the electric power supplied to the pressure-reduce linear valve to control the operation of the pressure-reduce linear valve,
• wherein the controller includes:
• a target-supply-pressure determining section configured to, on the basis of the operation of the braking operation member, determine a target supply pressure as a target of a supply pressure that is a hydraulic pressure of the working fluid supplied by the liquid-pressure source device;
• a supply-pressure-control executing section configured to selectively perform (a) a first control for making the supply pressure equal to the target supply pressure determined by the target-supply-pressure determining section, by supplying an electric power according to a difference between the supply pressure and the target supply pressure to the pressure-reduce linear valve where the supply pressure is higher than the target supply pressure and by supplying the electric power according to the difference between the supply pressure and the target supply pressure to the pressure-increase linear valve where the supply pressure is lower than the target supply pressure, and (b) a second control for making the supply pressure fall within a target range whose upper limit value is determined to be a value obtained by adding an upper-limit determining additional value to the target supply pressure and whose lower limit is determined to be a value obtained by reducing a lower-limit determining reduction value from the target supply pressure, by continuing to supply an electric power for opening the pressure-reduce linear valve to the pressure-reduce linear valve where the supply pressure is equal to or higher than the upper limit value, and by continuing to supply an electric power for opening the pressure-increase linear valve to the pressure-increase linear valve where the supply pressure is equal to or lower than the lower limit;
• and
• a control selecting section configured to, (i) where the ABS valve device is not being operated, select the first control as the control to be performed by the supply-pressure-control executing section and, (ii) where the ABS valve device is being operated, select the second control as the control to be performed by the supply-pressure-control executing section where the supply pressure is equal to or higher than the target supply pressure and is equal to or lower than a pressure obtained by adding a pressure-reducing threshold-value determination additional value greater than the upper-limit determining additional value to the target supply pressure, and select the first control as the control to be performed by the supply-pressure-control executing section where the supply pressure is higher than the pressure obtained by adding the pressure-reducing threshold-value determination additional value to the target supply pressure,
• wherein the controller further includes an ABS-valve-device operation-completion dealing section configured to perform a dealing control for dealing with a situation in the situation in which the completion of the operation of the ABS valve device is estimated, and
• wherein the ABS-valve-device operation-completion dealing section is configured to perform, as the dealing control, at least one of:
• (A) reducing the pressure-reducing threshold-value determination additional value;
• (B) reducing the upper-limit determining additional value;
• (C) increasing the electric power being supplied to the pressure-reduce linear valve where the first control is being performed at a point in time when the completion of the operation of the ABS valve device has been estimated;
• and
• (D) reducing the target supply pressure determined by the target-supply-pressure determining section.