To a transmission of a motor vehicle, a hydraulic pressure is supplied by a hydraulic pump. In a motor vehicle which carries out what is called an idle stop (an idling stop) that an engine is stopped during the stop of a vehicle in view of saving energy, an electric hydraulic pump is used to assuredly supply the hydraulic pressure to the transmission even during the idle stop.
Since the electric hydraulic pump for the motor vehicle is mounted on a restricted space of a vehicle body, compactness is requested, and further, lightness and a decrease of cost are also requested. In order to respond to such requests, an electric pump unit is proposed that has a pump, an electric motor for driving the pump and a controller of the electric motor attached to a common unit housing (for instance, see patent literature 1).
In the electric motor in this kind of electric pump unit, a DC brushless motor using a permanent magnet for a rotor is employed. In a usual DC brushless motor, a ring shaped or a segment shaped permanent magnet is fixed to an outer peripheral surface of a cylindrical rotor main body by an adhesive agent (for instance, see patent literature 2).