GB946597A - Fluid flow machine - Google Patents

Abstract

946,597. Bearings. ROLLS-ROYCE Ltd. May 22, 1962 [May 29, 1961], No. 19355/61. Heading F2A. [Also in Division F1] A gas turbine engine comprises an engine casing within which is mounted in flow series compressor means, combustion equipment and turbine means; shafting carrying the compressor means and the turbine means; bearing means within which the shafting is rotatably mounted; bearing support structure which is secured to the engine casing and which supports the bearing means; and connecting means for connecting the bearing support structure to the bearing means so that the latter is supported by, but may move radially of the bearing support structure. The connecting means comprises an intermediate member attachedly secured to the bearing support structure, the intermediate member having a frictional surface against which the bearing means is resiliently urged. The engine shown is a twin-spool type gas turbine propeller engine, the low pressure compressor 13 and low pressure turbine 17 being mounted on a common shaft 20, and the high pressure compressor 14 and high pressure turbine 16 being mounted on a common shaft 18 disposed around the shaft 20. The bearing 27 at the downstream end of the shaft 20 is shown in Fig. 2, the bearing comprising an outer race 55 which is located within a support structure 38 which is secured to support struts 33. An annular channelsection member 40 is secured to the radially-extending flange portion of the support structure 38 by means of bolts 37, a cylindrical sleeve 52 being disposed around each bolt, a ring member 45 faced with friction material 46 being clamped between the member 40 and the structure 38 by the sleeve. The outer race 55 is formed with a radially-extending flange 58 which extends into the annular channel member 40 and is held against the friction material 46 by means of a series of springs 66, two of which are disposed between each pair of bolts 37. A frusto-conical member 63 is provided adjacent the flange 58 of the outer race 55, the member 63 being in sealing engagement with the shaft 20 at 61, 62. The peripheral flange of the member 63 also extends into the annular channel member 40, the flange 63 being held against the flange 58 by means of springs 70, each spring 70 being disposed around a spring 66. The flanges 58 and 63 are formed with openings 59 and 64 respectively to permit passage of the sleeves 52, the openings 59, 64 being of larger diameter than the sleeve to permit radial movement of the bearing member 55 and sealing member 60 relative to the support structure 38. The bearing 36 which supports the downstream end of the shaft 18 is shown in Fig. 7, the outer bearing housing 71 being formed with a radially-extending flange 72 and with an axially-extending portion 73, a thickened end portion 74 of the portion 73 engaging with a support structure 75. The portion 73 is relatively thin and permits radial movement of the bearing member 71 relative to the support member 75. An annular channel section member 77 and a ring member 83 faced at its upstream side with friction material 84 are secured to the support member 75 by means of bolts 85 and sleeves 81, the sleeves passing through holes 80 in the channel member 77 and holes 86 in the radial flange 72 of the bearing member 71. The flange 72 lies against the friction material 84 at its downstream face and its upstream face is engaged by an annular spring plate 87, springs 90 disposed between the spring plate and the annular member 77 acting to force the flange 72 of the bearing member against the friction material. The annular member 77 is also formed with holes 92 disposed between adjacent pairs of holes 80, a sleeve 93 extending through each hole 92 and through a hole in the spring plate 87 to engage against the upstream face of the flange 72; a flange 95 on the sleeve engages against the spring plate 87. A bolt 96 extends through the sleeve 93, the head of the bolt engaging against the sleeve and the other end of the bolt being screwed into a radial flange 97 of a sealing member 98. Distance pieces 103 are disposed around the bolts between the radial flanges 97 of the sealing member and 72 of the bearing member 71. The assembly comprising the spring plate 87, bearing member 71, distance pieces 103 and sealing member 98 is secured together by the bolts 96, but the assembly is free to move radially by reason of the various annular clearances, the axial extension 73 of the bearing member permitting movement of the assembly by its resilience. The springs 90 act to maintain the assembly in position by urging the flange 72 into engagement with the friction material 84. Arrangements are made to cause a flow of cooling air around the bearing 27 as indicated in Fig. 11, the bearing 27 and the end of the shaft 20 being enclosed by a sealed housing 110. Cooling air flows through the hollow struts 33 and through the ducts 124 to the space between the housing 110 and the enclosing walls 113, 118, the air finally discharging through the spaces 119, 116 and then through passage 125.