| 摘要 |
PURPOSE:To prevent the deterioration of the strength of a permanent magnet compared to that in the conventional device, by furnishing a coordination magnetic circuit at the outer periphery of the permanent magnet. CONSTITUTION:A permanent magnet 1 of a self-sustainging solenoid has the magnitism in the direction of the thickness, and a fixed absorption body 2 made of a magnetic material is furnished thereover. The fixed absorption body 2 and a movable iron core 3 are absorbed or released at an absorption surface 4. Between the permanent magnet 1, the second fixed yoke 6b, a coordination collar 12, and the fixed absorption body 2, a coordination magnetic circuit 13 is formed without including the movable iron core 3. At the top of the iron core 3, a spring bearing 10 is installed, and a compression spring 11 is furnished between the bearing 10 and the first fixed to yoke 5a. In such a composition, no penetration hole is necessary make at the center of the permanent magnet 1 as is in the conventional device, and the deterioration of the strength of the permanent magnet can be prevented.
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