A rotary electric machine (a motor generator) serving as a driving prime mover and a power generator is installed also in a working machine such as a skid steer loader and a compact track loader in addition to the hybrid automobile. As the motor mentioned above, a permanent magnet motor providing a compact size and a high power is often employed. The permanent magnet motor needs to be prevented from the overheating in order to continue the normal operation. In addition, since the permanent magnet motor requires a large capacity of cooling per unit volume, a highly efficient cooling system is preferable, and a cooling system in which a liquid is circulated is particularly preferable. A motor employing a liquid cooling method (hereinafter referred to as a liquid-cooled motor) includes a stator that forms a magnetic path at equal circumferential intervals, a motor case that is fitted to the outer circumferential surface of the stator, and a cooling liquid passage formed between the outer circumferential surface of the stator and the inner circumferential surface of the motor case. The applicant of the present invention has filed the application of the liquid-cooled motor mentioned above that is a liquid-cooled motor configured to cool the stator and the motor case evenly in the circumferential direction without intervening the magnetic path of the stator (refer to the Japanese Unexamined Patent Application Publication No. 2014-230358).
In the liquid-cooled motor disclosed in Japanese Unexamined Patent Application Publication No. 2014-230358, the stator winding of the stator projects the end portion of the stator winding outward from the left side surface of and the right side surface of the stator, a width of the motor case in the axial center direction is formed to be larger than a width of the stator in the axial center direction so as to cover the end portion of the stator winding, and a liquid-supplying tube having an annular shape is arranged facing the outer circumferential side of the left and right side surfaces of the stator (radially outward from the stator winding) and the end portion of the inner circumferential surface of the motor case in the axial center direction. The liquid-supplying pipe includes an annular pipe portion positioned on the outer circumference of the side surface of the stator and communicating with all of the liquid-flowing tubes and includes at least one communicating pipe connected to the annular pipe portion and having the inside communicating with the annular pipe portion, and the communicating pipe is connected to a pump by a hose or the like, the pump being provided outside the motor.