Fluid pressure control apparatus/process

A fluid pressure control apparatus for controlling an output fluid pressure of a solenoid valve, the fluid pressure control apparatus comprising:

• a current controlling section to calculate a command current for driving the solenoid valve to achieve a target pressure in accordance a hysteresis correction quantity;
• and
• a correcting section to calculate the 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 a current increasing direction and a current decreasing direction, by using a predetermined reference hysteresis relationship which is defined in a predetermined reference current range from a predetermined turn current lower limit to a predetermined turn current upper limit, the correcting section including,
• a turn detecting section to detect a turn of the command current from one of the current increasing and decreasing directions to the other at a position between the turn current lower limit and the turn current upper limit of the reference current range, and
• a turn adjusting section to adjust the hysteresis correction quantity in dependence on the position of the turn when the position of the turn is intermediate between the turn current lower limit and the turn current upper limit of the reference current range.

A fluid pressure control process for controlling an output fluid pressure of a solenoid value, the fluid pressure control process comprising:

• a current controlling step of calculating a command current for driving the solenoid valve to achieve a target pressure in accordance a hysteresis correction quantity;
• and
• a correcting step of calculating the 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 a current increasing direction and a current decreasing direction, by using a predetermined reference hysteresis relationship which is defined in a predetermined reference current range from a predetermined turn current lower limit to a predetermined turn current upper limit, the correcting step including,
• a turn detecting step of detecting a turn of the command current from one of the current increasing and decreasing directions to the other at a position between the turn current lower limit and the turn current upper limit of the reference current range, and
• a turn adjusting step of adjusting the hysteresis correction quantity in dependence on the position of the turn when the position of the turn is intermediate between the turn current lower limit and the turn current upper limit of the reference current range.