VALVE DEVICE AND HYDRAULIC ACTUATOR CONTROL DEVICE

摘要

PROBLEM TO BE SOLVED: To dispense with a load hold check valve or drift reducing valve in a meter-in/meter-out separation type control circuit to control the working fluid of a hydraulic actuator. SOLUTION: Meter-in valves A1IMV and A2IMV of a bridge circuit installed in a passage leading from a pump 1 to a hydraulic actuator 2 are configured so that a poppet valve 41 is provided in such a way as contacting with and separating from a seat part 49 and a spring chamber 51 is provided oppositely to the part 49 about the poppet valve 41, wherein the chamber 51 is fitted with a built-in spring 52 to press the poppet valve 41 to the seat part 49. A high pressure selecting means selects either the pressure in the passage 13 on the pump side or the pressure in the passage 15 on the actuator side, whichever is the higher, and leads it to the spring chamber 51. A pilot spool valve 54 is formed with a smaller diameter than the poppet valve 41 so as to control the rate of pilot flow flowing out from the spring chamber 51 to either the passage 74 on the side nearer the pump than the poppet valve 41 or the passage 73 on the actuator side, whichever is the lower.