Patent GB-582282-A (GB)
Title: Improvements in and relating to rotary air pumping apparatus
IPC: F04C28/08
Filed: 1943-09-22
Abstract: 582,282. Variable-speed gearing. SULLIVAN MACHINERY CO. Sept. 22, 1943, Nos. 15574 and 15575. Convention dates, July 25, 1942, and Sept. 17, 1942. [Class 80 (ii)] [Also in Group XXVI] A meshing-screw type of compressor includes a change-speed device operated either automatically or manually. Power for the automatic system is obtained from a hydraulic gear-pump 162, Fig. 4, which also supplies oil for lubrication purposes. The compressor rotors 32, 33 are mounted on shafts coupled by gear 107, 108 or gears 60, 61, a hydraulic clutch 118 being provided. The gears 60, 61, on shafts 41, 43, have helix angles which correspond in hand and lead to the helix angles of the compressor rotors. A driving clutch comprising rollers 84 in recesses 33 couple a ring 86, integral with the gear 61, and the gear 60, and two rotors 32, 33 are driven. If a hydraulic clutch with plates 117, 118 is loaded, the plates are pressed together causing a gear 108 to be connected directly to a driving shaft 70, to drive the gear 107, and so the gears 60, 61 and the rotors, and because the gear 61 will then be rotated faster than the member 82, and in the same direction, there will be an over-running clutch action and no connection between gear 61 and member 82. Hydraulic pressure for the clutch is derived from the pump 162, supplied with oil from a sump 160, and being driven from the stub shaft 42 through gears 175, 174, and 172, 171. Oil flows through passages 179, 180, through a strainer 183 to passages 186, 187, to a distribution chamber 189. The oil then flows through further passage 190, 212, 241, 248, 251, 255. The oil in the tube 255 moves a piston 261 to the left, against pressure of a spring 264, and allows oil to press the clutch discs together and cause the gear 108 to become the rotor-driving element. This higher speed will be kept up until the speed of the rotors reaches such a value as to cause centrifugal weights to act on a valve 218, to .move the valve, against spring pressure, to shut off the oil supply to the tube 255. The clutch plates 117, 118 are then released, and the slower gear drive takes over. A manually-rotatable valve 244, Fig. 4 and 11, normally used for test purposes, may be operated by a handle 245 to restore the high-speed drive by allowing the oil to by-pass the speed-governed valve 218; or preclude the high-speed drive completely. A sping- loaded valve 278 maintains a sufficient pressure in the chamber 189 when the compressor is running, to ensure the operation of the speedchange mechanism. When the compressor is started up, the valve 136 is open, preventing compression of the air within the working chamber. When the aircraft reaches a high altitude, the drop in atmospheric pressure causes a valve 297 to close, and oil will be supplied through passages 289, 292, 156, to a chamber 155, raise a piston 148 and close the valve 136. The latter is hinged to a pin 141. A spring 145 normally holds the valve 136 open. Oil for lubrication purposes is supplied from the chamber 190 and passes through passages 194, 195, 197, 104, 198, into a chamber 199. Fluid is then delivered through a tube 200 to orifices 202, 203, for the gears and drains through a tube 205 and smallbore tube 206 (and large-bore tube 207) into the sump 160. The tube 206 is provided to prevent all of the lubricant in the sump from flowing into the chamber 201, when the aircraft is diving. Drain plugs are provided for the sump. A chamber 230 is connected to the atmosphere, and a spring 302 causes the valve 297 to keep open normally at aircraft height below 25,000 feet. Oil from the chamber 289 passes through a passage 312 to the interior of a bellows 304. The compressor inlet 53 may be fitted with a strainer and the casing 31 has cooling fins 316.