GB779688A - Pressure regulating valve arrangement - Google Patents

Abstract

779,688. Fluid-pressure servomotor-control systems. SOC. ALSACIENNE DE CONSTRUCTIONS MECANIQUES. Aug. 3, 1955 [Aug. 18, 1954], No. 22336/55. Class 135. A pressure regulating valve arrangement for holding the fluid-pressure in a circuit 1 between two limits and including pressure responsive control means 3, 20, 15 for a circuit pressure generating means 14 comprises a shuttle valve 41, 42 co-operating with two seats 5<SP>1</SP>, 62 of different cross-sections provided in a common chamber 24 communicating through one of the seats 6<SP>2</SP> with the circuit, to a low pressure zone, e.g. atmosphere at 9 through the other seat 51 and at 2 to the control means, a pressure responsive member 11 subject to the circuit pressure and operatively connected to the shuttle valve to urge it towards the smaller seat 5<SP>1</SP>, and elastic means 12 continuously urging the pressure responsive member against the circuit pressure, the cross-section of the pressure responsive member being greater than the sum of the cross-sections of the seats. It is shown mathematically that the difference between the pressure limits for the circuit may be made very small by making the area of the piston or diaphragm 11 greater than the sum of the areas of the seats. When the circuit pressure approaches its upper limiting value it depresses the piston 11 against tension spring 12 to close the valve 4<SP>1</SP> and open the valve 42 so that circuit pressure moves the control piston 18 to the right to open the switch 20 and stop the driving motor 15 and pump 14. When the circuit pressure approaches its lower limit the valve 4<SP>2</SP> is closed and the valve 4<SP>1</SP> opens to exhaust fluid pressure from the control piston to atmosphere so that the piston moves to the left and switches on the motor and pump. In another embodiment a single ball valve is provided in the chamber 24 co-operating with opposite seats.