Patent GB-645848-A (GB)
Title: Improvements in or relating to elastic fluid actuated power systems
IPC: F01D5/08
Filed: 1947-10-17
Abstract: 645,848. Rotary engines. AKTIEBOLAGET LJUNGSTROMS ANGTURBIN. Oct. 17, 1947, No. 27814. Convention date, April 3. [Class 110(ii)] [Also in Group XII] A method of producing power, using a meshing-screw engine, in which clearances are maintained between the rotors and the casing bores, comprises using high-temperature compressed working fluid which is expanded in chambers formed by the screw rotors, the surfaces of which are cooled either by the working-fluid, prior to its being heated or by other cooling medium. No internal lubrication is used in the engine. Steam or other gas may be used as cooling media. In one form a power plant comprises a meshing-screw engine 10, using a working- fluid at very high temperature, and a meshing-screw compressor 18 supplying air for a combustion chamber 46 -- and also cooling the engine rotors and casing parts. Preferably a heat-exchanger 42 is used heated by exhaust gases from the engine to pre-heat compressed air which has cooled various parts of the engine. Both engine and compressor are preferably of the type described in Specification 627,162. Packing strips 112, 114 are fitted on the rotors 12, 14 (Fig. 4). Engine and compressor rotors 12. 20 are connected by a shaft 26 and coupling 28. Compressed air is delivered through a chamber 32, passes through cooling channels in the casing and rotors, then through channels 38, 40, 44, combustion chamber 46, where fuel is injected through a burner 48, The gases are admitted to the engine through nozzles 50 and exhausted to the heat-exchanger through a port 52, and through outlet 56. Power is taken off through a shaft 58. The engine casing comprises a barrel 58 and end plates 60, 62, and is provided with cooling passages 64a, 64b. leading to passages 72 and 38 in the heatexchanger. A cooling channel 76, round the exhaust port 52, is supplied with air from a passage 74, and discharges to a port 80, chamber 82 to passage 72. The rotor 12 is built up of a centre, welded, part 12a and end members 12b, 12c. Cooling passages 88 are supplied with air 'from a hollow shaft 92 and discharged through a hollow shaft 106 leading to the passage 38. Rotor 14 is similarly cooled. A diaphragm 110, Fig. 3, prevents a direct connection between inlet and outlet shafts 94, 108. The pairs of rotor shafts are coupled by gears 116. 118. High pressure cooling air flows from grooves round the shafts into the clearance spaces between the rotor ends and the end plate, and a part mingles with the motive fluid. Another part flows through packings 132, 134 of labyrinth type. The leakage air cools the shaft ends and is discharged to atmosphere through vents 136, 138. Lower pressure air is used to cool the rotor ends at the exhaust end. Rotor shafts 92, 94 are carried in bearings 158, 160 and are provided with thrust bearings 162, 164. Seals 166, 168 prevent compressed air from the chamber 32 from entering the bearing chamber. The compressor may have a water packet or other cooling means. Fig. 8 shows a plant having a compressor 300 and engine 310. Baffles 320, provided with ports 322, 324, are integral with the engine rotors. Air from the compressor passes from a passage 330 to a distributing chamber 332, a portion flowing through the engine rotors to a duct 334 leading to the re-heater 336. Another portion flows through passages 338 to jacket spaces 340, duct 342 to the inlet 334 of the re-heater. A third portion flows through a passage 344 to an annular space 360 in the combustion chamber. This is at a higher pressure than the air coming from a duct 348. The pressure differential creates high velocity flow through the space 360. Blast furnace gas may be added to the compressed air. The air may pass through a surface heater. Multi-stage compression and expansion of the fluid may be used. Some compressed air may be used for external purposes. The rotors may be of lightweight material, mild steel or stainless .steel. Temperatures used are given in the Specification.