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1. WO1981002768 - FLUID CIRCUIT WITH ZERO LEAK LOAD CHECK AND BY-PASS VALVE

Publication Number WO/1981/002768
Publication Date 01.10.1981
International Application No. PCT/US1980/000321
International Filing Date 24.03.1980
IPC
F15B 13/01 2006.01
FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
13Details of servomotor systems
01Locking-valves or other detent devices
CPC
F15B 13/01
FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
13Details of servomotor systems
01Locking-valves or other detent ; i.e. load-holding; devices
Applicants
Inventors
Priority Data
US80/0032124.03.1980WO
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) FLUID CIRCUIT WITH ZERO LEAK LOAD CHECK AND BY-PASS VALVE
(FR) CIRCUIT DE FLUIDE AVEC SOUPAPE BY-PASS ET DE RETENUE DE CHARGE DE FUITE ZERO
Abstract
(EN)
A load check valve is normally employed in association with a double-acting hydraulic cylinder, such as the type used to raise and lower the boom of a construction vehicle. Conventional check valves of the poppet type are difficult to modulate whereas check valves of the spool type generally do not insure leakage control at an acceptable rate during normal operation. The spool-type load check valve (20) of this invention, used in conjunction with additional check check valves (60, 61), overcomes the latter problem by providing a series of interconnecting passages and chambers (36) for communicating equalized fluid pressure from a cylinder (11) to either end of the spool (27) thereof to provide for minimal leakage. When a pair of such cylinders (11, 12) are utilized, the load check valves (20, 20") associated therewith are interconnected by a balance line (50) and resolver valves (47") to insure equalization of fluid pressure in the cylinders upon actuation thereof and to further insure a gradual descent of a load carried by the cylinders upon loss of fluid pressure between the check valves.
(FR)
Une soupape de retenue de charge est normalement utilisee en association avec un cylindre hydraulique a double effet tel que ceux qui sont utilises pour relever et rabaisser la fleche d"un vehicule de construction. Des soupapes de retenue conventionnelles du type a clappet sont difficiles a regler tandis que les soupapes de retenue du type a tiroir n"assurent pas d"une maniere generale une commande de fuite acceptable pendant le fonctionnement normal. La soupape de retenue de charge du type a tiroir (20) de cette invention, utilisee en combinaison avec des soupapes de retenue supplementaires (60, 61), resoud ce probleme en prevoyant une serie de passages et de chambres (36) d"interconnexion pour assurer la communication d"une pression de fluide egalisee provenant d"un cylindre (11) vers l"une et l"autre des extremites de son tiroir (27) pour assurer une fuite minimum. Lorsqu"une paire de ces cylindres (11, 12) sont utilises, les soupapes de retenue de charge (20, 20") associees aux cylindres sont interconnectees par une ligne d"equilibre (50) et des soupapes de resolution (47") pour assurer l"egalisation de la pression du fluide dans les cylindres lors de leur fonctionnement et pour assurer en outre une descente progressive d"une charge portee par les cylindres en cas de perte de la pression de fluide entre les soupapes de retenue.
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