To prevent insulation deterioration from accelerating, by appropriately maintaining the temperatures of components in a main motor without decreasing the cooling, and to prevent shortening the between overhauls intervals.

This main motor of a vehicle takes in the outside air through a cyclone air cleaner device with a fan inside the main motor loaded on a dally of a vehicle, passes the air through a rotor and a stator as cooling air, and discharge the air from an exhaust opening. The cyclone air cleaner device includes a cylinder for taking in the outside air, a separating dust discharge path for discharging the dust and moisture collected from the cylinder, and a discharging path for taking in the outside air of which the dust and moisture are removed in the cylinder into the main motor.