Patent GB-1178410-A (GB)
Title: Improvements in Gas Turbine Engine Lubrication System.
IPC: F01D25/18
Filed: 1967-08-30
Abstract: 1,178,410. Gas turbine engines - bearings. GENERAL ELECTRIC CO. Aug.30, 1967 [Dec.1, 1966], No. 39591/67. Headings F1G and F1J. The invention relates to a gas turbine jet engine of the kind comprising two co-axial compressor and turbine rotor assemblies and to means for lubricating the engine bearings and to means for pressurising sealing chambers which enclose the bearing sump chambers. The engine shown is a gas turbine ducted fan engine of the front fan type, and comprises a fan or LP compressor 32, an HP compressor 24, combustion equipment 25, HP turbine 53 and LP turbine 35, the HP turbine driving the HP compressor through outer shaft 49, and the LP turbine driving the LP compressor through inner shaft 33. The LP rotor assembly is supported at its forward end in spaced apart bearings 36, 37 and at its rearward end in spaced bearings 41, 44. The HP rotor assembly is supported at its forward end in a bearing 54, at an intermediate point in bearings 56 and at its rearward end in a bearing 62. A bearing 64 is disposed between the two rotor assemblies at an intermediate point. The two bearings 36, 37 are enclosed within a first sump chamber 65 which also encloses the bearing 54 of the HP rotor assembly. The two bearings 56 located at an intermediate position of the HP rotor assembly are enclosed within a second sump chamber 68, the bearing 62 at the rearward end of the HP rotor assembly and the bearing 41 of the LP rotor assembly are enclosed within a third sump chamber 72, and the bearing 44 at the rearward end of the LP rotor assembly is enclosed within a fourth sump chamber 74. The sump chambers are all provided with sealing means adjacent their ends to prevent leakage of lubricating oil therefrom. The sump chambers 65, 68, 72 and 74 are themselves enclosed within pressurized chambers 79, 106, 87 and 94 respectively to reduce oil leakage through the seals. The chamber 79 is pressurized by air taken from the outlet of the LP compressor 32 through openings 77 in the support struts 23, the air passing through openings 78 into the chamber 79. Air flows from the chamber 79 through outlets 127 into the hollow passage within the inner shaft which passage is closed at its rearward end by a cap 95, the air passing outwardly through openings 92 and 96 in the shaft to the pressurized chambers 87 and 94 respectively. The sump chamber 55 of the bearing 54 is enclosed by a pressurized chamber 98, Fig.3, to which pressurized air is supplied from within the hollow support struts 23 through openings 97. Air passas from the chamber 98 through openings 103 into the space within the HP compressor rotor drum 47, the air discharging therefrom through openings 105 into the pressurized chamber 106 of the sump chamber 68. The pressurized chambers 106 and 87 associated with the sump chambers 68 and 72 are enclosed within vent chambers 112 and 114 respectively, the chamber 112 being connected to a point of relatively low pressure at the nozzle outlet of the ducted fan through the hollow guide vanes 59 and duct 110 whereby the pressurized chamber 106 is continuously replenished with relatively cool pressurized air. The vent chamber 114 is likewise connected to a point of relatively low pressure at the outlet of the LP turbine 35 through openings 117 in the end walls of the LP turbine rotor drum 34. The pressurized chamber 94 is connected to the same point of low pressure through the seal 93. Lubricating oil is supplied to the bearings through nozzles such as 76 shown adjacent the bearings 62, 41. Oil is supplied from the nozzle 80 to the inter-shaft bearing 64.