| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cogging torque without dropping the output torque. SOLUTION: A bonded magnet 10 is in the shape of a hollow cylinder which has a peripheral thick part 12 in its circumference, centering upon an axis 11. The range B of about 135°in electric angle is an electric angle section which generates torque mainly, and the range A of about 45°in the electric angle is a transition section where the direction of magnetic vector at the surface of a magnet changes. In the electric angle section B, it is magnetized so that the magnetic vector at the surface of the magnet may go roughly in the direction of the normal of the circumference of the peripheral thick part 12 and that the magnitude may be equal. Moreover, in the electric angle section A, it is magnetized as shown in Fig. so that the magnetic vector may have the tangent components of in circumferential direction and that the density of the surface magnetic flux in normal direction of the component of its normal may decrease or increase gradually accompanying the progress of the electric angle. The change properties of the surface magnetic flux density in the normal direction at the surface of the magnet at 2π(one cycle) in electric angle are ones shown in Fig. 2. COPYRIGHT: (C)2004,JPO
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