Patent GB-1455608-A (GB)
Title: Gas turbine engines
IPC: F01D25/12
Filed: 1974-02-13
Abstract: 1455608 Gas turbine engines GENERAL ELECTRIC CO 13 Feb 1974 [26 Feb 1973] 6613/74 Heading F1G The invention relates to gas turbine engines and to the bearing assemblies and pressurized seal chambers associated with the bearing chambers. The invention is described with reference to a gas turbine ducted fan or by-pass type engine comprising LP compressor or fan 18, HP compressor 32, combustion equipment 62, HP turbine 36 which drives the HP compressor through outer shaft 14, and LP turbine 22 which drives the LP compressor or fan through inner shaft 12. The HP assembly 14 is supported in bearings 68 at the upstream end and 70 at the downstream end; the LP assembly 12 is supported in bearing 64 at the upstream end in bearing 66 at an intermediate position, and in bearing 72 at the downstream end. The bearing 64 is located in a bearing chamber 84, the two bearings 66 and 68 are located in a bearing chamber 86, and the two bearings 70 and 72 are located in a bearing chamber 88. The bearing 64 is supplied with lubricating oil through line 90 and nozzle 92; bearing 66 through line 94 and nozzles 95, 96; bearing 68 through line 94 and nozzles 97, 98; bearing 70 through opening 105 and bearing 72 through nozzle 104, oil being supplied to the downstream bearings through line 100 which extends through strut 82. The bearing chamber 84 is formed with a pressurized seal chamber 111 to which pressure air is supplied through line 178. The bearing chamber 86 is formed with pressurized seal chambers 118 and 123, pressure air from chamber 123 passing through lines 176, 180, 182 to the seal chamber 118, air from line 176 also passing through lines 177, 178 (which extend through struts 76, 74) to the seal chamber 111. The bearing chamber 88 is formed with pressurized seal chambers 127 and 129 to which air under pressure is supplied through duct 158 formed in the outer shaft assembly 14, the air entering seal chamber 127 through inlet 162, then passing through duct 160 to the other seal chamber 129. The bearing chamber 88 is vented to atmosphere through ducts 166, 168, 169, 170, 204 and 172. Lubricating oil is supplied to the chamber 88 through line 100 to the metering and scavenge pump 102, the oil being discharged to the bearings 70, 72 through ducts 105 and 104. The scavenge oil pump 102 takes its suction through inlet 184 and delivers scavenge oil through passage 187 within the inner shaft assembly 12, the oil passing through radial passages 192, 193, 194 and thence into the bearing chamber 86 from which it is returned to the oil tank. Oil is supplied through line 94 to nozzles which discharge to the bearings 66, 68 in bearing chamber 86 and bearing 64 in bearing chamber 84. Air for pressurizing the seals, also for cooling, is tapped from the HP compressor 32 through opening 32 in the rotor assembly, into the chamber 138 in which are disposed blades 140, the air then dividing into three streams, the streams 142 acting to cool the HP end of the compressor 32 then the turbine rotor discs 146, 148 then passing through opening 150 in the HP rotor assembly to the chamber 149 through opening 155 in the LP rotor assembly to the chamber 157 so cooling the LP turbine rotor discs, the air being finally vented to atmosphere. A second stream of air from chamber 138 passes through bore 156 to the passage 158 in HP shaft assembly 14, the air passing through opening 162 in the HP rotor assembly to the pressurized seal chambers 127, 129. The third stream of air from the chamber 138 passes forwardly through opening 174 in the HP compressor rotor assembly to the pressurized seal chamber 123; the air then passes through lines 176, 180 to the pressurized seal chamber 118 also through line 177, 178 to the pressurized seal chamber 111 as described above. The bearing chamber 86 is vented through outlet 197 to the space 200 within the LP shaft assembly 12, the air passing through opening 202 into chamber 170 thence together with air vented from the bearing chamber 88 through outlet 204 and duct 172, to atmosphere. Discharge oil from the - bearing chamber 88 passes through outlet 184 (shown displaced through 180 degrees) to the scavenge pump 102 from which it is discharged through duct 187 in the LP shaft assembly into the bearing chamber 86 from which it is drained by means not shown.