| 摘要 |
PROBLEM TO BE SOLVED: To improve the stability, and the vibration and noises of the whole system by preventing the pressure pulsation caused by the chattering of a back- pressure control valve provided on a discharge passage side of a poppet valve from being applied to a pilot system to mitigate the pulsation in the flow rate of the poppet valve. SOLUTION: The make-up function when the negative pressure is generated in a circuit is promoted by increasing the back pressure of the main flow rate discharged into a discharge passage 25 via the poppet valve 42 of the pilot flow rate amplification type to control the main flow rate by the pilot flow rate using a back pressure check valve 59. A pilot stage valve 64 to displace the poppet valve 42 by controlling the pilot flow rate is communicated with the discharge passage 25 via a pilot passage 63. An expansion type hydraulic muffler 71 to filter and damp the pressure pulsation caused by the chattering of the back pressure check valve 59 propagating in the direction opposite to the direction of the pilot flow rate from the pilot stage valve 64 is inserted in this pilot passage 63.
|
