Fluid pressure control apparatus and process

摘要

A fluid pressure control apparatus for controlling a solenoid valve to increase and decrease a fluid pressure by varying a valve opening degree includes a controller to control the fluid pressure by varying a command current for driving the solenoid valve. The controller calculates a hysteresis correction quantity to reduce a hysteresis effect of a hysteresis characteristic of the fluid pressure outputted from the solenoid valve with respect to the command current varied in an increasing direction and a decreasing direction, and varies the command current to control the fluid pressure to a target pressure in accordance with the hysteresis correction quantity. The controller calculates the hysteresis correction quantity in accordance with a turn-to-turn variation quantity determined from a current difference between a first command current value at a first changeover of a varying direction of the command current from one of the increasing and decreasing directions to the other and a second command current value at a second changeover of the varying direction of the command current before the first changeover.