| 摘要 |
PURPOSE:To contrive reduction in leakage flux as well as to increase the magnetic field intensity in the air gap located between static magnetic field generating means by a method wherein the static magnetic field generating means, consisting of a permanent magnet and a magnetic pole, for example, which are fixed to a yoke, and the yoke member to be arranged on the circumference of the region where the above-mentioned static magnetic field generating means are positioned leaving the prescribed distance. CONSTITUTION:A protruded part 5a made of the same material as the frame body of a yoke 5 is formed on the yoke 5. A permanent magnet 7, to be fixed to the tip part, and the yoke members 5b and 5c are separated by the protruded part 5a leaving the prescribed distance between them. These yoke members 5b, 5c, and 5c and the protruded part 5a and at least the permanent magnet 7 which constitutes a magnetic field generating means are in the relation of L1>=L2/4 for the distance L1 between both inside surfaces of the yoke members 5c and 5c and the opposing two side faces of the permanent magnet and the width L2 of the permanent magnet as shown in the diagram. Also, the height of the protruded part 5a indicated by H1 is brought into the relation of H1>=H2 against the thickness H2 of the permanent magnet. Through these procedures, the leakage magnetic flux generating on the region ranging from the permanent magnet 7 or magnetic pole 6 to the adjoining yoke part can be reduced and, at the same time, the increase in effective magnetic field passing an air gap 8 can be achieved.
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