| 摘要 |
PURPOSE:To prevent the generation of unstable condition by slowing down the moving speed of a plunger and vibrating it at center position by providing the guide pipe made of non-magnetic and conductive material on the periphery of the plunger. CONSTITUTION:When the excitation of a coil 1c is released, the magnetic flux flowing in a plunger 3 declines rapidly from the magnetic flux (phi2+phi3) which is compounded by those of the coil 1c and a permanent magnet 8 to the magnetic flux phi2 only of the permanent magnet 8 and the return force of a right-side return spring 5 is applied to the plunger 3 intensively. Then the static condition in a neutral position becomes unstable. However, by the help of the conductive guide pipe 2 provided on the periphery of the plunger 3, the induced current generated in the direction for preventing the change of the magnetic flux, and the magnetic flux phi2 of the coil 1c does not rapidly decrease, but decreases at a certain time constant. Accordingly, the right-side return spring 5 does not apply an intensive force to the plunger 3 and moves the plunger to the neutral position smoothly. |
