| 摘要 |
PURPOSE:To permit a variable-gap type elecromagnetic actuator to have a large stroke and reduce its power consumption, by allowing a return spring against an electromagnetic attraction force to have such a non-linear characteristic that its stiffness becomes larger as the gap decreases. CONSTITUTION:A fluid flows as shown by an arrow 13. In the state where no current flows through a coil 8, a poppet valve 11 is pressed on a nozzle 12 by the force F0 of a return spring 9. The magnitude of the force F0 is determined so that if a predetermined differential pressure is applied the fluid is not allowed to flow. When current flows through the coil 8, a plunger 4 is attracted by the force F of a core 3. As a result, the return spring 9 is slightly deflected to produce a gap between the nozzle 12 and the poppet valve 11, thereby allowing the fluid to flow. As the current increases, the gap increases correspondingly, so that the fluid flows at a higher flow rate. When deflected, the spring 9 is simultaneously brought into close contact with a pipe holder 7 by l1 and with a valve holder 10 by l2. In consequence, the effective span of the return spring 9 is reduced, and the spring 9 strongly resists, so that a non-linear characteristic can be obtained. |
