| 摘要 |
PURPOSE:To reduce noise by using a poppet back pressure chamber as damper chamber, thus stabilizing the poppet. CONSTITUTION:The working oil discharged from a pump 67 flows into a pilot variable throttle 51 through the input port 52 of a main valve 50, variable throttle 65, passage 64, and an output port 54. The pressure after passing through the variable throttle 65 is represented by Pp. The pressure PB in a poppet back part pressure chamber 55 is represented by Pp when a poppet is in standstill state. When the opening area of the pilot variable throttle 51 is increased, the poppet 59 starts to rise, and the working oil in the poppet back part pressure chamber 55 flows, passing through a fixed throttle 66, and the variation of pressure PB is generated in the direction for reducing the speed of the poppet 59 by the differential pressure before and behind the throttle 66. Thus, the poppet 59 can be stabilized.
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