摘要 |
An exciting coil is wound on a cylindrical yoke provided with a pair of pole teeth, a cylindrical permanent magnet where N pole and S pole are magnetized in a radial direction is disposed so as to be movable in a hollow portion of the yoke and the permanent magnet is coupled to a spool by a magnet holder, and a displacement sensor is disposed in a hollow portion of the permanent magnet so as to be positioned on a center axial line of the permanent magnet, so that the displacement of the permanent magnet is detected by the displacement sensor and the degree of opening of the spool is controlled by performing feedback of the displacement to a control portion.
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