| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve device capable of flowing a constant flow rate of working fluid to a flow control valve regardless of a load.SOLUTION: A valve device 42 comprises an electromagnetic proportional valve 45, a flow control valve 46, and an electromagnetic selector valve 47. A portion of a hydraulic flow passage 43 between the electromagnetic proportional valve 45 and a lift cylinder 4, and one side of a spool housing part 51 forming one part of the hydraulic flow passage 44 branched between the hydraulic flow passage 43 are communicated with each other via a pilot flow passage 49. Branch points of the hydraulic flow passages 43, 44 and the other side of the spool housing part 51 are communicated with each other via a pilot flow passage 50. The other side of the spool housing part 51 and a portion of the hydraulic flow passage 44 between the flow control valve 46 and the electromagnetic selector valve 47 are communicated with each other via the pilot flow passage 54. Orifices 55, 56 for generating a pressure difference in each flow passage are respectively provided on the pilot flow passages 50, 54. |
