GB561377A - Improvements in or relating to valves - Google Patents

Abstract

561,377. Valves. ERNST, W. Nov. 12, 1942, No. 15997. Convention date, Dec. 22, 1941.. [Classes 69 (ii) and 135] A fluid-operated valve for a hydraulic system has an inlet port, two outlet ports, and two service ports, the arrangement being such that the inlet port may be connected to one service port,' while the other service port is connected to an outlet. port, or one service port may be connected to one outlet port, while preventing connection between the other service port and the inlet port. The valve casing comprising a central member 11, Fig. 1, and end members 12, 13, has an inlet port 21 connected by a pipe 64 to a main pressure source 63, Fig. 7, ports 18, 19 connected by pipes 59, 65 to the ends of the press cylinder 52, and exhaust ports 17, 20 connected to a tank 61. The valve 23 is formed with cylinders 24, 25 receiving plungers 26, 36 carried by pistons 31, 40, working in cylinders 32, 41, bores 33, 49 being provided. An adjustable abutment 35 extends into the cylinder 32, and a piston 44 working in a cylinder 43 adjustably carries an abutment 48. The press circuit includes a pump 69 for operating the valve 23 under the control of three-way valves 82, 83, 84. A pressing cycle starting from the upper position of the ram 53 when the valve 23 and coacting parts are in the positions shown in Fig. 2, is initiated by connecting the cylinders 41, 24 to the tank 61 through the valve 83, and leaving the cylinders 32, 24, 43 in connection with the pump 69. The valve 23 and abutment 48 are thus moved and the ports 17, 18 put into communication as shown in Fig. 3, so that liquid escapes from the lower portion of the press cylinder to the tank and the ram moves down by gravity, the upper portion of the cylinder drawing from the tank through a make-up device 67. Built-up pressure closes the device 67 and the valve 84 is operated to connect the cylinder 43 to the tank so that the main valve elements move into the Fig. 4 position. The upper part of the press cylinder is then supplied from the source 63, through the pipes 64, 65, while the lower part is connected to the tank and the pressing stroke of the ram is completed. To retract the ram, the valves 82, 83, 84 are operated to connect the cylinders 32, 24 with the tank and the cylinders 43, 41, 25 with the pump 69, the valve 23 being thus moved into the Fig. 5 position, so that pressure is supplied to the lower end of the ram cylinder and the upper end exhausts to the tank. The valve 82 is then operated to admit pump pressure to the cylinders 32, 24 to return the valve 23 to the Fig. 2 position, so that pressure is neither admitted to nor withdrawn from the press cylinder. In the retracted position of the ram, a member 55 closes a valve 56, which opens if the ram should drop owing to leakage, to allow pump liquid to enter the lower portion of the cylinder and return the ram to its upper position.