Patent ID: 8752516

Claim:
A hydraulic control unit for use in a valve timing control apparatus having a housing adapted to be driven by a crankshaft of an internal combustion engine and configured to define a working fluid chamber therein, a vane rotor fixedly connected to a camshaft and rotatably accommodated in the housing so that the vane rotor rotates relative to the housing, the vane rotor having vanes configured to partition the working fluid chamber into a phase-advance chamber and a phase-retard chamber, a lock mechanism configured to be locked to enable the vane rotor to be held at an intermediate position between a maximum phase-advance position and a maximum phase-retard position, and configured to be unlocked by a working fluid pressure supplied thereto, a phase-advance passage configured to communicate with the phase-advance chamber, a phase-retard passage configured to communicate with the phase-retard chamber, and a lock passage provided for working-fluid-pressure supply-and-exhaust for the lock mechanism, comprising: a directional control valve unit including two directional control valves configured to be switchable among a first state, a second state, and a third state, the first state being a state where a discharge passage of a pump driven by the engine communicates with both the phase-advance passage and the lock passage and simultaneously the phase-retard passage communicates with a drain passage, the second state being a state where the discharge passage communicates with both the phase-retard passage and the lock passage and simultaneously the phase-advance passage communicates with the drain passage, and the third state being a state where the phase-advance passage, the phase-retard passage, and the lock passage all communicate with the discharge passage, one of the two directional control valves being a first directional control valve configured to control switching of each of the phase-advance passage and the phase-retard passage to either one of the discharge passage and the drain passage, and the other of the two directional control valves being a second directional control valve configured to control switching of the lock passage to either one of the discharge passage and the drain passage.