Patent ID: 8591378

Claim:
A controller for a power transmission system that uses an engine and a motor as driving force sources to transmit power, the power transmission system including a transmission unit that is arranged downstream of the driving force sources and has a plurality of engagement devices, wherein the transmission unit establishes a plurality of gears having different speed ratios by the engagement devices, the controller comprising: a torque transmission capacity setting unit that, when the transmission unit shifts gears, varies torque transmission capacities of the respective engagement devices on the basis of an operating state of the motor and an operating state of the engine, wherein: when the engine is started at a time of a downshift of the transmission unit during a motor drive mode in which only the motor is used as the driving force source, the torque transmission capacity setting unit decreases a torque transmission capacity of a release-side frictional engagement device among the plurality of engagement devices of the transmission unit and increases a torque transmission capacity of an engage-side frictional engagement device among the plurality of engagement devices of the transmission unit, as compared with when the engine is already in operation.