Patent ID: 8825318

Claim:
An automatic transmission comprising: a mechanical oil pump configured to be driven by a rotation of an engine transmitted thereto; an intake passage through which a working oil suctioned into the mechanical oil pump flows; a discharge passage having a narrowed portion, through which the working oil discharged from the mechanical oil pump flows; a connecting passage that connects the intake passage to the discharge passage on an upstream side of the narrowed portion in a flow direction of the working oil while bypassing the mechanical oil pump; a flow control mechanism including a spool that is configured to set the connecting passage in a communicative state when a differential pressure between an oil pressure on the upstream side of the narrowed portion in the flow direction of the working oil and an oil pressure on a downstream side of the narrowed portion in the flow direction of the working oil exceeds a predetermined value, and is configured to set the connecting passage in a non-communicative state when the differential pressure is equal to or lower than the predetermined value; and a control device comprising: an oil temperature detecting unit configured to detect an oil temperature of the working oil; an engine torque calculating unit configured to calculate an engine torque; a line pressure setting unit configured to set a line pressure to be higher as the engine torque increases; a determining unit configured to determine whether the oil temperature is equal to or higher than a predetermined oil temperature at which the connecting passage switches from the communicative state to the non-communicative state due to air mixed into the working oil and whether the engine torque is equal to or smaller than a predetermined engine torque at which the connecting passage switches from the communicative state to the non-communicative state due to the air mixed into the working oil; and a line pressure correcting unit configured to raise the line pressure above the line pressure set by the line pressure setting unit when the determining unit determines that the oil temperature is equal to or higher than the predetermined oil temperature and the engine torque is equal to or smaller than the predetermined engine torque.