Magnet embedded motor, rotor unit, and method for manufacturing rotor unit

#This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2005-115639, filed on Apr. 13, 2005, and Japanese Patent Application 2006-028486, filed on Feb. 6, 2006, the entire content of which is incorporated herein by reference.

#This invention relates to a magnet embedded motor and a rotor of an inner rotor type brushless motor. More particularly, the present invention pertains to a rotor unit including a rotating body rotated by means of a rotor and method for manufacturing the rotor unit.

#Conventionally, a rotating magnetic field type motor which is provided with a magnet serving as a field source at a rotor side includes a magnet embedded motor which is provided with the magnet embedded in the rotor. JP2000-175388A and JP2004-194472A respectively disclose a fixing structure of the magnet embedded motor. According to the magnet embedded motor disclosed in JP2000-175388A, a fixing spring is provided in a magnet insert hole formed on the rotor and the magnet is fixed by means of a biasing force of the spring. According to the magnet embedded motor disclosed in JP2004-194472A, the magnet is applied with an adhesive (a silicone resin based adhesive, or the like) and the magnet is thereby fixed in the magnet insert hole.

#The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein:

#FIG. 1 is a sectional view schematically illustrating a structure of a motor.

#FIG. 2 is a sectional view schematically illustrating a structure of the motor and a pump apparatus.

#Embodiments of the present invention will be explained hereinbelow with reference to the attached drawings.

#A first embodiment of the present invention will be explained hereinafter. An interior permanent magnet motor applied to a pump apparatus (i.e., a water pump) will be explained hereinafter. With reference to FIG. 1, the motor 50 (i.e., au interior permanent magnet motor) includes a rotor 10 having plural magnets 2 which are embedded therein. The rotor 10 is provided with, at an outer side thereof, a stator 52 having a three phase (U, V, W) motor coil (not shown). A rotating magnetic field is formed and the rotor 10 upon an energization of a motor coil. Further, the rotor 10 is rotated based on a relation between magnetic field flux of the magnet 2 and the rotating magnetic field.

#As illustrated in FIG. 2, the rotor 10 includes a yoke 1 at which a magnetic pass of the magnet 2 is formed. The yoke 1 is formed with second holes 4 into which each magnet 2 is inserted. According to the first embodiment of the present invention, the yoke 1 is formed by laminating magnetic steel plates. Further, according to the first embodiment of the present invention, the rotor 10 includes four magnets 2, and the yoke 1 which is formed with four second holes 4 corresponding to the magnets 2 in a circumferential direction thereof in regular intervals (appox. 90 degree intervals). The rotor 10 is formed with the magnet 2 and the yoke 1 into a single member by means of an insert resin molding (i.e., an injection molding) by making the magnet 2 and the yoke 1 as an insertion body.