JPH01139102U

JPH01139102U -

Info

Publication number: JPH01139102U
Application number: JP3434788U
Authority: JP
Priority date: 1988-03-15
Filing date: 1988-03-15
Publication date: 1989-09-22
Anticipated expiration: 2003-03-15
Also published as: JPH0740721Y2

Description

[Brief explanation of drawings]

第１図は本考案の第１実施例を示す回路構成図
、第２図は本考案の第２実施例の要部を示す回路
構成図、第３図は従来装置の回路構成図である。１…液圧源、２…液圧シリンダ、２Ａ…第１シ
リンダ室、２Ｂ…第２シリンダ室、３…重量物、
４…リザーバ、５…第１開閉弁、７…第２開閉弁
、９…第３開閉弁、１１…第４開閉弁、１３…第
１パイロツト切換弁、１８…第２パイロツト切換
弁、２１…パイロツト流路、２３，２３′，３０
，３２…絞り弁、２４…圧力制御弁。 FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing main parts of a second embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional device. DESCRIPTION OF SYMBOLS 1... Hydraulic pressure source, 2... Hydraulic pressure cylinder, 2A... First cylinder chamber, 2B... Second cylinder chamber, 3... Heavy object,
4... Reservoir, 5... First on-off valve, 7... Second on-off valve, 9... Third on-off valve, 11... Fourth on-off valve, 13... First pilot switching valve, 18... Second pilot switching valve, 21... Pilot flow path, 23, 23', 30
, 32...throttle valve, 24...pressure control valve.

Claims

[Claims for Utility Model Registration] Disposed in a flow path connecting between the first cylinder chamber and the hydraulic pressure source, the volume of which increases as the heavy object descends from the hydraulic cylinder, and selects between the first cylinder chamber and the hydraulic pressure source. It is arranged in a flow path that connects the first pilot-type opening/closing valve that automatically cuts off communication with the hydraulic pressure source, and the second cylinder chamber whose volume decreases due to the descent of a heavy object in the hydraulic cylinder and the hydraulic pressure source. A pilot-type second on-off valve that selectively cuts off communication between the pressure sources; and a pilot-type second on-off valve that selectively cuts off communication between the first cylinder chamber and the reservoir, which is disposed in the flow path connecting the first cylinder chamber and the reservoir. a third on-off valve; a fourth pilot-type on-off valve that is arranged in the flow path connecting the second cylinder chamber and the reservoir and selectively cuts off communication between the second cylinder chamber and the reservoir; and behind the first on-off valve. A first switching position for introducing pilot fluid into the chamber and discharging the pilot fluid in the rear chamber of the third on-off valve; a first pilot switching valve having a second switching position for discharging the pilot fluid; 4. A second pilot switching valve having a second switching position for introducing pilot fluid into the rear chamber of the second opening/closing valve and discharging the pilot fluid from the rear chamber of the second opening/closing valve, and connecting between the second cylinder chamber and the reservoir. A pilot flow path that introduces the pilot fluid taken out from the flow path that is the primary side of the fourth on-off valve into the rear chamber of the fourth on-off valve; a plurality of throttling means; and a pressure control valve that opens when the pilot fluid introduced through the pilot flow path exceeds a predetermined pressure and controls the opening of the fourth opening/closing valve based on the differential pressure across the throttling means. A fluid control device comprising: