Toyota Jidosha Kabushiki Kaisha

Toshiaki Mitsui

Yusuke Ohgata

Providing a hydraulic control apparatus for a vehicular automatic transmission, which makes it possible to design an oil pump with a reduced delivery capacity, thereby permitting an improvement of fuel economy of a vehicle. The hydraulic control apparatus includes a supply passage connecting/disconnecting valveA which is operated, in synchronization with a switching operation of a lock-up relay valve, to apply a modulator pressure PM via an orificeto a lock-up clutch, for placing the lock-up clutchin the lock-up on state, and to inhibit the application of the modulator pressure PM to the lock-up clutch, for placing the lock-up clutchin its lock-up off state. Accordingly, the modulator pressure PM via the orificeis not applied to the lock-up clutchwhen the lock-up clutchis placed in the lock-up off state, so that a total amount of flow and consumption of the working oil is reduced, making it possible to design the oil pumpwith a reduced delivery capacity, thereby permitting an improvement of fuel economy of the vehicle.

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Nagoya, Japan

Toshiaki Mitsui