A vehicle driving apparatus includes a rotating shaft driven by the power source, a fluid pump driven by the rotating shaft. The fluid pump includes a rotor rotated by the rotating shaft, and a case. The case includes a fluid discharge port provided on an inner peripheral surface of an insertion hole through which the rotating shaft is inserted. The rotating shaft includes an attachment portion fittable to a shaft hole, and an internal flow path. A supply groove communicating with the internal flow path is provided on an outer peripheral surface of the rotating shaft. The fluid pump is attached to the attachment portion of the rotating shaft such that positions of the discharge port and the supply groove in an axial direction of the rotating shaft overlap each other. The attachment portion is provided on each of both sides of the supply groove in the axial direction.

An oil pump is provided. The oil pump comprises a shell, a rotor mounting part on the shell, and a rotor mechanism disposed on the rotor mounting part. The shell has an inlet and an outlet and defines a low-pressure oil chamber and a high-pressure oil chamber therein. A buffer chamber is defined between the low-pressure oil chamber and the high-pressure oil chamber, and a barrier wall is disposed between the buffer chamber and the low-pressure oil chamber. An engine cover comprising the oil pump and an engine comprising the engine cover are also provided.

A mounting structure for electric oil pump is provided to allow the electric oil pump to be mounted without through a communication pipe. The electric oil pump includes a pump unit having an inscribed gear pump, and a motor unit disposed adjacent to the pump unit and having a sensorless brushless DC motor for rotating the inscribed gear pump. A transmission accommodates the electric oil pump and includes a transmission case having an oil pan. The electric oil pump is attached to the transmission case with at least a through hole for supplying working oil to the pump unit being submerged in the working oil reserved in the oil pan.

A first fitting portion is coupled to a protruding end of the crankshaft to be rotatable about a crankshaft rotational axis. An intermediate member includes a first hole wall slidably supporting the first fitting portion in a first direction orthogonal to the crankshaft rotational axis so that the intermediate member rotates together with the crankshaft. An inner rotor includes a second hole wall slidably supporting the second fitting portion in a second direction orthogonal to the first direction and the crankshaft rotational axis so that the inner rotor rotates together with the intermediate member. One of the first direction and the second direction is in parallel with a line segment joining the crankshaft rotational axis and an axis of a crankpin of the internal combustion engine which is closest to the protruding end of the crankshaft.