| 摘要 |
<p>Two groups of magnetic poles (74. 78) are formed on each end of a columnar yoke (72) Four magnetic poles (74a, 74b, 74c, 74d, 78a, 78b, 78c. 78d) of each magnetic pole groups protrude from the center of the yoke at right angles to the longitudinal direction thereof. A ring-shaped magnetic pole (82, 136) is formed on that portion of the yoke between the first and second magnetic pole groups. Ring-shaped permanent magnets (86, 88, 144, 146) are fitted on the yoke between the ring-shaped magnetic pole and the two magnetic pole groups A cylindrical magnetic field adjusting member (90, 122) is fitted on the magnetic poles and the permanent magnets Outside of these members, a magnetic coupling member or ring-shaped member (90. 176) of a supported body is disposed coaxially with the magnetic field adjusting member. The magnetic coupling member is formed of a highly permeable magnetic material, and the magnetic field adjusting member is made of a magnetic material whose permeability is a little lower than that of the magnetic coupling member. With use of the magnetic field adjusting member, magnetic fluxes produced by coils wound around the magnetic poles and the yoke are spread in the circumferential direction of the magnetic field adjusting member between the magnetic field adjusting member and the magnetic coupling member.</p> |
