GB905860A - Improvements in or relating to lubricating arrangements for bearings in gas turbine engines - Google Patents

Abstract

905,860. Lubricating systems. ROLLSROYCE Ltd. Jan. 13, 1960 [Jan. 20, 1959], No. 2169/59. Class 12 (3). [Also in Group XXVI] A gas-turbine engine has a rotor shaft supported adjacent the engine air intake by a front bearing, and a lubricating oil supply system is provided for the front bearing and comprises oil supply and oil scavenge conduits extending within the shaft forwardly to the bearing, and a scavenge pump is provided being driven from the shaft and arranged to withdraw oil from a sump in stationary structure adjacent the bearing and to deliver the oil to the scavenge conduit. The forward end of a compressor shaft 10 of a gas-turbine engine is shown supported in a journal bearing 11 which is carried by means of inlet guide vanes 13 from the outer casing 12 of the compressor air intake. An oil supply conduit 17 and an oil scavenge conduit 18 are disposed coaxially within the rotor shaft 10. An end fitting 24 is located within the end of the oil supply pipe 17 and comprises an annular portion 26 connected to the portion 24 by means of radial webs 25 which are provided with bores 31 through which oil is delivered from the conduit 17. The annular portion 26 is provided at its forward end with a radial flange 27 which terminates in a cylindrical extension 28 having external splines 29 and internal splines 50. The splines 29 engage with internal splines 23 formed within the rotor shaft 10 while the splines 50 engage external splines 52 formed on a frusto-conical driving sleeve 51. A ring member 19 is secured to the end of the scavenge conduit 18, an annular flange 19c within the member 19 engaging with the annular portion 26 of the end fitting 24. A frusto-conical flange 19a extends from the forward end of the member 19 and terminates in a cylindrical extension 19b which is formed with external splines 22 at its forward end and with apertures 33. The extension 19b abuts at its rearward end against a shoulder 21 formed within the shaft 10 and the splines 22 engage with the internal splines 23 formed within the shaft. The end fittings 19 and 24 are secured by means of a ring nut 30 engaging within the end of the shaft. Oil from the conduit 17 is delivered through bores 31 into the chamber 32 and flows from there through outlets 33 into a groove 34 formed in the rotor shaft 10, the oil then passing through bores 35, 36 to lubricate the bearing 11. The oil draining from the bearing is collected in a sump 40 formed by a ring 37 which is secured to the outer race 11a of the bearing, the ring 37 engaging at its forward end with an axial flange formed integrally with the end wall 39. Oil is drawn off from the sump 40 by means of a scavenge pump comprising pump gears 41, 44, the pump having a suction pipe 46 and discharge passage 54. The pump gear 41 is secured to a shaft 42 which carries a driving pinion 43 which engages with a pinion 48 mounted coaxially with the rotor shaft 10, the pinion 48 being drivingly connected to the shaft 10 by means of the frusto-conical driving sleeve 51, the internal splines 53 at the forward end of which engage with the pinion 48. Scavenge oil from the passage 54 passes into the hollow bore within the shaft 48a of the pinion 48 and then passes through transfer duct 58 and thence to the scavenge conduit 18. Cooling air is supplied from within the shaft 10 through apertures 61 to flow externally of the bearing, finally discharging through outlets 66 into the air intake passage. In the case of a two-shaft type of engine in which the oil supply pump is driven from the shaft of the high-pressure compressor while the scavenge pump is driven from the low-pressure compressor, means in the form of a spring-loaded valve may be provided to restrict the quantity of oil delivered to the forward bearing until such time as the scavenge pump has attained sufficient speed to be capable of dealing with the full flow of oil. The valve is disposed within a chamber forming an extension of the cylindrical portion 24.