Dispositif maintenant entre deux valeurs données la pression dans des circuits hydrauliques

摘要

988, 780. Fluid-pressure servomotor systems. ANDRE CITROEN S.A. Jan. 31, 1962 [Feb. 28, 1961], No. 3719/62. Heading G3P. A device for maintaining pressure in an accumulator Ac between two predetermined limits, the accumulator being supplied with fluid from a supply A past a non-return valve S and having an outlet Y to a circuit comprises two slide valves T1, T2 subjected at one end to accumulator pressure and loaded to the position shown by springs R1, R2 in separate chambers E1, E2. The spring R1 is calibrated to balance a force due to the lower limit pressure acting on valve T1 and spring R2 is calibrated to balance the upper limit pressure. The chamber E1 is connected to the supply A by a restricted passage F and to drain B by a passage H under control of the valve T2. The chamber E2 is connected to the drain B by a passage K and the valve T1 controls connection of the supply A to the drain B. In operation fluid is fed to the accumulator until its pressure reaches the upper limit when valve T2 moves downwards to open chamber E1 to drain. The fall in pressure in chamber E1 allows the valve T1 to move downwards and connect the supply A to drain B. When the pressure in the accumulator drops below the upper limit the valve T2 moves upwards but due to the restricted passage F, the valve T1 remains open until the pressure in the accumulator reaches the lower limit when the valve T1 again closes. If the fall in the accumulator is slow the valve T1 closes before the lower limit is reached.