| 摘要 |
The solenoid includes an electrical coil having a central opening in which is fixedly located a rod formed of a material of the type capable of being magnetized when in a magnetic field. A plunger is supported for movement toward and away from one end of the rod. A permanent magnet is supported by the plunger. In one embodiment the permanent magnet is located such that the plunger and permanent magnet are held next to the coil when the coil is in a deactivated condition. When the coil is activated, the magnetic field produced by the coil repels the permanent magnet and hence the plunger away from the coil. The polarity of the permanent magnet can be reversed in position such that normally the permanent magnet and hence the plunger are normally repelled away from the rod end when the coil is in a deactivated condition. When the coil is activated in a given manner, the magnetic filed of the coil pulls the magnet and hence the plunger next to the coil. In another embodiment two permanent magnets are attached to opposite ends of a plunger of the type unaffected by a magnetic field to form a push-pull type of solenoid.
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