GB445382A - Improvements in or relating to valve controlling devices - Google Patents

Abstract

445,382. Fluid-pressure servomotorcontrol systems. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(A. W. Cash Co. ; Decatur, Illinois, U.S.A.) Feb. 4, 1935, No. 3536. [Class 135] A valve mechanism for use as an automatic-control device comprises two inlet ports 22, 23 and two outlet ports 24, 25 with one valve co-operating with each pair of inlet and outlet ports for controlling the flow of pressure fluid through the ports, the valves being operated by a member 29 located between them and extending through one of each pair of ports into contact with the valves. A passageway 16 connects the two inlet ports 22, 23 and can be connected at 11, Fig. 1, to a source of fluid pressure, and the exhaust ports 24, 25 open into a chamber 18 having an exhaust opening 12. Intermediate each pair of ports are radial openings 42 to chambers 19, 20 having outlets 14, 15, Fig. 2, respectively which are connected by pipes to a doubleacting cylinder which is to be operated by the pressure fluid. Ball valves 27, 28 are operated as the member 29 is reciprocated, so as to close the inlet port and open the exhaust port of one pair of ports, and with the reverse action on the other pair of ports. Pressure fluid is thus supplied to one end of the double - acting cylinder while the other end is open to exhaust. As shown, the member 29 is reciprocated by a lover 45 which passes through a flexible metal diaphragm 46 separating the chamber 18 from a chamber 68 in a casing 64 divided into two chambers 67, 68 by a flexible diaphragm 44. The lever 45 consists of two parts flexibly connected by flanges 80, 81 pressed together by a spring 82 enclosed in a hollow cap 83. The central part of the diaphragm 44 is clamped between two plates 59, 60, and the plate 59 has one end of the lever 45 pivoted thereto. while a tension spring 72 adjustable by means of a screw-andnut 73, 74 is attached to the upper plate. Outlets 69, 70 to the chambers 67, 68 provide means whereby differential pressure may be applied to the diaphragm 44 so as to actuate the valve mechanism. In the example described, the chambers 67, 68 are connected to the two sides of an orifice plate situated in a pipe, the flow through which is to be controlled. As the flow varies, the diaphragm 44 is moved, thus moving the member 29 and altering the position of the valves 27, 28. Movement of the piston in the double-acting cylinder thus takes place, and the piston is connected to a butterfly valve in the pipe which is operated to keep the flow constant.