摘要 |
A hydraulic control unit is configured to switch among a first state where a discharge passage of a pump driven by an internal combustion engine communicates with both a phase-advance passage and a lock passage and simultaneously a phase-retard passage communicates with a drain passage, a second 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 a third state where the phase-advance passage, the phase-retard passage, and the lock passage all communicate with the discharge passage. The hydraulic control unit is further switchable to a fourth state where the discharge passage communicates with both the phase-advance passage and the phase-retard passage and simultaneously the lock passage communicates with the drain passage.
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