Patent ID: 6581378
Filing Date: 2003-06-24
Classification: E02F,F15B,F16H

Abstract:
A valve device for at least one hydraulic motor suitable for driving a mass of large inertia, the motor being designed to be connected to a fluid circuit which includes two main ducts, namely a fluid feed duct adapted to be connected to a hydraulic pump and a fluid discharge duct, which ducts are suitable for being closed off when the motor is not operating, and an auxiliary duct adapted to be connected to a booster pump which delivers fluid at a lower pressure than a pressure of said fluid delivered by said hydraulic pump, the device including first and second main conduits serving to be connected to respective ones of the two main ducts of the fluid circuit, and an auxiliary conduit serving to be connected to the auxiliary duct of said circuit, the device including a moving member suitable for being urged between two end positions as a function of the difference between the fluid pressures prevailing in the first and second main ducts, wherein in a first end position of said moving member, with a fluid pressure in the first main duct being greater than a fluid pressure in the second main duct, said moving member puts said second main conduit in communication with said auxiliary conduit via a calibrated constriction passageway, while the first main conduit is isolated from said second main conduit and from said auxiliary conduit, and in a second end position, with a fluid pressure in the second main duct being greater than a fluid pressure in the first main duct, said moving member puts the first main conduit in communication with said auxiliary conduit via said calibrated constriction passageway, while said second main conduit is isolated from said first main conduit and from said auxiliary conduit, said device further including time delay means suitable for limiting the speed of transition between one and the other of said first and second configurations when a difference between pressures in the first and second main ducts changes sign, said time delay means comprising first and second damping chambers which are continuously in communication with said auxiliary conduit via calibrated constriction means that are calibrated to hinder the flow of fluid at least in the direction in which the chambers are emptied.