GB969786A - Oil discharge pump for a gas turbine engine - Google Patents

Abstract

969,786. Lubricating. ROLLS-ROYCE Ltd. Sept. 13, 1962 [Sept. 20, 1961], No. 33727/61. Heading F2A. [Also in Division F1] An oil-discharge pump for a gas turbine engine has a piston mounted within a cylinder, means urging the piston towards a predetermined position so that a space is formed between the piston and one end of the cylinder, an oil inlet duct and an oil outlet duct both of which communicate with said space, an oil inlet valve which controls flow through the oil inlet duct and which is urged towards the open position, an oil outlet valve which controls flow through the oil outlet duct and which is urged towards the closed position, and has means for moving the piston to decrease the size of said space so as to increase the pressure of the oil in the oil inlet and oil outlet ducts and cause the oil inlet valve to close, the oil outlet valve to open, and a shot of oil to be forced out through the oil outlet ducts. In an embodiment, an oil-discharge pump 20 has a body 23 which comprises an upper part containing a reservoir 24 and a lower part which forms a cylinder. A lower part 26 of the cylinder has a piston 30 therein and a higher part 27 of the cylinder has a larger diameter than the part 26 and has a piston 31 therein. The piston 31 is positioned relatively to an end 33 of the cylinder part 27 so as to form a space 34 and is urged downwardly by a spring 35. The piston 30 is positioned relatively to the piston 31 so as to form a space 37 and is urged downwardly by a spring 38. The body 23 has a first oil inlet duct 39 and a first oil outlet duct 46 in communication with the space 37 and has a second oil inlet duct 40 and a second oil outlet duct 47 in communication with the space 40. The inlet ducts 39, 49 are supplied with oil from the reservoir 24 via non-return valves 41, 42 which are urged towards their open positions by springs 44, 45 respectively. The outlet ducts 46, 47 have non-return valves 48, 49 which are urged toward their closed positions by springs 50, 51 respectively. The piston 30 has a skirt portion 54 which slidably engages both the inner wall of the cylinder portion 26 and a fixed piston 55, the latter is integral with the body 23, has passages 56, 57 therein, and defines with the lower end of the cylinder part 26 a space 60 which communicates with a drain passage 61. The passage 57 connects an annular groove 64 of the fixed piston 55 to a fuel tank 66, Fig. 3, which, having a backing-pump 67, supplies fuel to a conduit 70, which incorporates in flow series a fuel pump 71, a shut-off cock 72, and a fuel flow control unit 73; the conduit 70 leading to burners 74 of the combustion equipment. When the fuel-pump 71 is operated, high-pressure fuel is received by a space 63 which is formed between the fixed piston 55 and the piston 30, so that the latter is raised along with the piston 31. The spaces 34, 37 are reduced; the valves 42, 41 are closed; the valves 49, 48 are opened; a single shot of oil is passed through a pipe 21 which connects the space 34 with a chamber 18 of a bearing 16 and another single shot of oil is passed through a pipe 22 which connects the space 37 with a chamber 19 of a bearing 17. When the fuelpump 71 is not in operation, the pistons 30, 31 are in the positions as shown in Fig. 2, having been returned by the springs 38, 35. Specification 943,858 is referred to.