PURPOSE: To reduce leakage of magnetic flux at a yoke by forming at least one part of the yoke of a permanent magnet of rare earth - iron alloy mainly composed of R-T-M.
CONSTITUTION: A yoke part 3a of a yoke 4 consisting of a yoke member 2 and a yoke part 3a of a magnetic circuit 1 is formed of a rare earth - iron permanent magnet mainly composed of R-T-M. The permanent magnet 3 consists of a permanent magnet alloy of rare earth mainly composed of R-T-M, while integrally forming the yoke part 3a and a field generation part 3b. However, R consists of one kind or above two kinds of rare earth elements such as Nd and Pr, from which a high magnetic characteristic is obtainable, relatively cheap Ce, mischmetal, Dy and Tb, from which high holding force is obtainable. T consists of one kind or above two kinds of Fe, Co, Ni of transition elements of an iron group and Mn of transition elements excepting the iron group. M consists of one kind or above two kinds of B, C, P, Si and Ti, Zr as well as other elements.
WATANABE TERUO
YOSHIKAWA NORIO
