| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce cogging torque at low costs.SOLUTION: In a direct drive motor having a rotor in which a magnet is attached to a back yoke, a clearance peripheral groove is provided at a magnet attachment surface end part of the back yoke. Preferably, with respect to a radial direction thickness of the back yoke, the thickness at a periphery in its axial direction is larger than that at a magnet attachment part, and a difference in thickness is a half or less of a thickness of the magnet. Preferably, an outer periphery and an inner periphery of the magnet are concentric circular peripheral surfaces, and a magnet width is made uniform in a circumferential direction. Preferably, circumferential widths of the magnet and a stator tooth front end are different from each other.</p> |
