| 摘要 |
PURPOSE: A pilot valve and a servo valve having a closed nozzle in a normal state without a control signal are provided to reduce energy consumption by 90% or more. CONSTITUTION: A pilot valve and a servo valve having a closed nozzle in a normal state without a control signal comprise a pressure reducing device. The pressure reducing device does not consume energy while there is no control signal, since a nozzle is close. The pressure reducing device opens the nozzle in portion to the size of the control signal, makes pressure difference between both ends of a spool(19) and controls the movement of the spool. A nozzle flapper servo valve does not consume energy while there is no control signal, since a flapper(18) blocks both nozzles(16,17). The nozzle flapper servo valve opens a nozzle, which is distant from the flapper, since the flapper moves according to the size of the control signal.
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