JPS6182105U - - Google Patents

Description

[Brief explanation of drawings]

Fig. 1 is an explanatory circuit diagram showing one embodiment of the present invention, Fig. 2 is a circuit diagram showing the embodiment of Fig. 1 with symbols, and Fig. 3 is a circuit diagram showing an embodiment for horizontal drive. Figure 4 is a circuit diagram showing Figure 3 with symbols, Figures 5 and 6 are circuit explanatory diagrams showing other embodiments of horizontal drive, and Figures 7 and 8 are circuit diagrams showing conventional examples. It is a diagram. 1: Hydraulic cylinder, 1a, 1b: cylinder chamber,
2: Load, 4, 4a, 4b: Pilot check valve, 6: Poppet valve element, 7: Piston, 10: Directional control, 11: Valve body, 12: Spool valve element, 13: Spring, 14: Tank, 15, 1
6a, 16b, 17: land, 18, 18a, 1
8b, 19d, 27: Internal passage, 20, 20b,
21, 22, 23: annular groove, 25: hydraulic pressure source, 30
: Check valve, P: Pump port, T: Tank port, Pc: Pilot operation port, A, B: Load connection port.

Claims (1)

[Claims for Utility Model Registration] (1) It has a hydraulic cylinder that is reciprocated by switching the hydraulic pressure of the main line, and has three switching positions including a neutral position by switching the spool valve body, and the pump port is in the neutral position. and a directional control valve that disconnects the tank port from the load connection port and alternately communicates the pump port and the tank port with the load connection port by straight connection or cross connection in the remaining two switching positions; and a load connection port of the directional control valve. and a pilot check valve, which is provided in at least one of the hydraulic systems connecting the hydraulic cylinders in a direction to be closed by the hydraulic pressure supplied from the hydraulic cylinder, and which opens in response to the supply of pilot operating hydraulic pressure, and further The directional control valve is a pilot check valve that, when the spool valve element is moved from a neutral position to at least one of the switching positions, supplies pilot operating hydraulic pressure to the pilot check valve to open it in the spool movement state immediately before the switching. A control circuit for a hydraulic cylinder characterized by having an operation port. (2) The directional control valve has a built-in check valve that closes in response to cylinder side hydraulic pressure in the middle of a passage communicating between the pump port and the pilot operation port. Hydraulic pressure control circuit as described in section.