Patent GB-191508377-A (GB)
Title: Improvements in and relating to Fluid Pressure Governing Mechanism.
Inventor: TURNER WALTER VICTOR
Filed: 1915-06-05
Abstract: 8377. Turner, W. V. Nov. 25, 1914, [Convention date]. Regulating delivery by varying speed and power of motor.-In a controlling-device for an electrically-operated pump, wherein the switch &c. is actuated by a piston, the fluid supply to which is controlled by cut-in and cut-out piston valves, the valve faces are exposed to reservoir pressure, and passages are provided whereby leakage past the faces when the valves are seated escapes to the atmosphere. The invention relates more particular to a controller of the poppet-valve type, such as is described in Specification 24,912/10, [Class 8 (i), Air and gases, Compressing &c.). The apparatus shown in Fig. 1 comprises a spring-pressed piston 3 within a casing, actuating a switch or controller 4. Fluid under pressure is admitted by a pipe 6 to the front faces of spring-pressed cut-in and cut-out valves 8, 12, which, when they are seated against the pressure, expose only part of their faces. The valve springs are enclosed in chambers 15, 16, connected together, the chamber 15 having a restricted atmospheric exhaust port 18. In operation, as the pressure rises, the valve 8 is first lifted from its seat, exposing its full face to the pressure, so that it is quickly pressed on to its rear seat 22, closing communication between spring casing 15 and a passage 20 leading to a part of the under face of the piston 3. Fluid then flows through a chamber 23 and a groove 24 below the valve 8 to the passage 20, but does not lift the piston. A further rise of pressure forces the valve 12 on to its rear seat, allowing fluid to pass through a chamber 26 and passage 19 to the space below the main area of the piston, which is lifted, opening the switch. On a fall of pressure, the valve 8 begins to return to its front position, and fluid passes by the passage 20 to the spring chamber 15. Owing to the restricted area of the port 18, pressure accumulates behind the valves 8, 12, and returns them to their front positions, cutting off the fluid supply to the piston chamber. When the controller is in the cut-in position, leakage past the valve seat 9 of the valve 8 can escape through the groove 24 and the chamber 15 to the atmosphere, while leakage past the seat 13 of the valve 12 passes by a groove 27, annular groove 28, and passage 29 to the chamber above the piston 3, which is connected to atmosphere. In the modification shown in Fig. 2, rising pressure first pushes the cut-out valve 34 back, uncovering a passage 48, by which the fluid is conveyed to a chamber 49 in front of the cut-in valve 31 and closes this valve on its rear seat. This movement uncovers a port 40, allowing fluid to pass through a passage 38 to the lower spring chamber, where the pressure returns the cut-out valve 34 to its front seat. With the valves in this position, fluid passes through ports 41, groove 42, and passage 43 to the piston chamber 2, and opens the switch. As the pressure falls, the valve 31 is returned to its front seat, allowing fluid from the piston chamber to flow by passage 47 to the upper spring chamber 44. Fluid also passes to this chamber through passages 43, 42, 41, 38. Leakage past the front seats of the valves flows by a passage 48 and a groove 51 to an annular groove 52 communicating with a passage 53 which leads to the passage 47 and the atmosphere.