GB718449A - Improvements in gas turbine engines - Google Patents

Abstract

718,449. Elastic-fluid turbines. GENERAL MOTORS CORPORATION. March 12, 1952 [March 20, 1951], No. 6374/52. Class 110(3) [Also in Group XXXIV] A gas turbine engine has a hollow shaft supported by one or more bearings and within the shaft are two co-axial tubes located one within the other and spaced from the inner surface of the hollow shaft and adapted for the flow of bearing lubrication fluid through the inner tube and in the annular space between the tubes. As shown, the shaft 12 of a gas turbine' is hollow and is supported at the forward end in a ball thrust bearing 13 and at the rear end in a roller bearing 14. A hollow tie-bolt 24 extends through the shaft 12, being secured thereto at one end by means of a nut 25 and towards the other end being positioned by a collar 26. Within the tie-bolt 24 is a tube 33 connected at one end to the tie-bolt by a sleeve 34 and at the other end being held in a plug 32 slidably mounted by means of O-ring seals 36 in circumferential grooves in the tie-bolt. Oil is pumped from a reservoir 29 through a pipe 31 to the tiebolt and passes through a passage 38 in the plug 32 to the annular space 40 around the tube 33. It reaches the bearing 13 by radial passages 52, 53, 54, 55 and returns to a sump 44 from which oil is pumped through a tube 51 to the reservoir 29. Oil for the bearing 14 flows from the space 40 through radial passages 63, 64, 65, 66 and is returned to a sump 72. The sump contains a rotary pump 75 driven from the turbine shaft 12 through gearing 77, 78 the gear 78 being integral with a hollow rotatable shaft 79 splined to the tie-bolt nut 25. The pump forces oil through a pipe 84 through the shaft 79 and the tube 33 and through a passage 41 in the plug 32 to radial passages, 43 in the tie-bolt 24 leading to splines between the turbine shaft 12 and a coupling shaft 21. The oil escapes past the splines to the sump 44. Means are provided for supplying cooling air to the machine. The housing 72 for the pump 75 is enclosed by a sheet metal casing 90 into which cooling air is supplied by way of a pipe 91 and ports 94, the air being discharged through the rear portion of the casing. Air also flows through ports 96 in an annulus 93 and between a bearing support ring 70 and a shield 97 so that the bearing 14 is protected from heat radiated from the turbine wheels. The lubricating oil is kept cool by the provision of heat shields 98, 99 of bright metal which are provided between the turbine shaft 12 and the tie-bolt 24. Air in the space between the shield 99 and the tie-bolt 24 is vented through openings 101 and 111. The space between the shields is sealed. Air is circulated through the space between the shield 98 and the shaft 12 by means of a centrifugal fan 106 delivering air through an opening 108 in the fan and through passage 103, the air discharging through outlets 104, 105.