| 摘要 |
PROBLEM TO BE SOLVED: To extend a lifetime of a bearing of an impeller by reducing wear speed of the bearing of the impeller and to improve efficiency by increasing degree of freedom in a shape of a stator core to reduce magnetic leakage. SOLUTION: In this DC motor, a stator core 1 includes a lower stator core 11 including even number not less than 4 of stator poles 11b having coil wire "m" wound thereon arranged with keeping even interval from an inner circumference side of the cylindrical stator core main body 11a, and an upper stator core 12 including a top part projection 12b formed at an inner circumference side with corresponding to a number of the stator pole 11b from a top end of a cylindrical upper stator core main body 12a. An inner rotor magnet 2 such as plastic magnet is magnetized with corresponding to number of poles of the stator core 1 which is an insulated sintered material core divided to an upper and a lower part, and is constructed to make upper and lower magnetic poles different. The magnetic pole of the top part projection 12b and the magnetic pole of the upper part rotor magnet main body 22 are controlled to attract and repulse each other. COPYRIGHT: (C)2009,JPO&INPIT
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