| 摘要 |
The linear actuator with movable magnets includes a cylindrical inner yoke; a magnet holder disposed concentrically with the inner yoke via a clearance; a first and a second cylindrical magnets which are magnetized in the radial direction and held by the magnet holder in the axial direction; and an outer yoke disposed concentrically with the inner yoke. The magnetized directions of the two magnets are opposite to each other. The outer yoke has a first and a second coil-disposed sections, around which a first and a second driving coils are wound, respectively. The outer yoke also has a plurality of magnetic pole sections that oppose, via a clearance, to at least one of the first and the second magnets. Besides, in the actuator, dimensional requirements are defined for the magnetic pole and the magnets. That is, (i) the axial length of a magnetic pole section is not less than a movable stroke; (ii) the axial length of each first and second magnet is equal to the sum of the axial length of a magnetic pole section and the axial length of each first and second coil-disposed section, respectively. With the structure described above, a magnetic force is effectively obtained for keeping a sufficient thrust. This allows the magnets to be lightweight, advantageously saving costs and resources. The lightweight of the magnets can reduce the total weight of the whole moving parts, thereby realizing a higher acceleration.
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