Fluid pressure control device

A fluid pressure control device that controls input and output of a fluid pressure to and from a fluid chamber in a fluid transfer device that transfers power from a motor via a working fluid in the fluid chamber, the fluid chamber being partitioned into an engagement oil chamber and a disengagement oil chamber by a lock-up clutch, the lock-up clutch being turned off by inputting the fluid pressure to the disengagement oil chamber and discharging the fluid pressure from the engagement oil chamber, and the lock-up clutch being turned on by stopping input of the fluid pressure to the disengagement oil chamber and inputting the fluid pressure to the engagement oil chamber, the fluid pressure control device comprising:

• a signal pressure output valve that performs pressure regulation to output a signal pressure;
• a control valve that is connected to an output source flow passage leading to an output source of the fluid pressure, a disengagement-oil-chamber flow passage leading to the disengagement oil chamber, and a drain passage, and that switchably establishes, in accordance with the signal pressure from the signal pressure output valve, a first state in which communication between the output source flow passage and the disengagement-oil-chamber flow passage is allowed and communication between the disengagement-oil-chamber flow passage and the drain passage is blocked, a second state in which communication between the output source flow passage and the disengagement-oil-chamber flow passage is blocked and communication between the disengagement-oil-chamber flow passage and the drain passage is blocked, and a third state in which communication between the output source flow passage and the disengagement-oil-chamber flow passage is blocked and communication between the disengagement-oil-chamber flow passage and the drain passage is allowed;
• and
• a control unit that controls the signal pressure output valve such that the control valve establishes the first state when the lock-up clutch is turned off, controlling the signal pressure output valve such that the control valve establishes the third state when the lock-up clutch is turned on, and controlling the signal pressure output valve such that the control valve establishes the second state so that the working fluid can be confined in the disengagement oil chamber when the lock-up clutch is switched from off to on.