Patent GB-839961-A (GB)
Title: Improvements in or relating to engine accessory mounting arrangements
Inventor: HISCOCK GEORGE HENRY
IPC: F02C7/32
Filed: 1956-11-01
Abstract: 839,961. Gas turbine plant. BRISTOL SIDDELEY ENGINES Ltd. Oct. 1. 1957 [Nov. 1, 1956], No. 33429/56. Class 110 (3). An engine accessory mounting arrangement, such as for use in a gas turbine engine, for securing to the outside of the engine casing an accessory device having a moving part connected by a mechanical transmission to a moving part within the engine casing, comprises a cylindrical wall which surrounds an opening in the casing of the engine and connecting means providing a fluid-tight connection between the accessory device and the cylindrical wall while allowing at least slight relative movement between the accessory device and the cylindrical wall in a plane perpendicular to the axis of the latter. At least two struts are provided each attached at one end to the accessory device and at the other to the engine casing, the struts constituting the sole means of support and location of the accessory device relative to the casing, the mechanical transmission extending from inside the casing to the accessory device through the opening. In the gas turbine engine shown, the low-pressure compressor 20 is mounted on the same shaft 21 as the low-pressure turbine 22, and the highpressure compressor 23 is mounted on the same shaft 24 as the high-pressure turbine 25, the engine accessories comprising governor unit 31, fuel pump 32 and low- and high-pressure lubricating oil pumps 33, 34 which are contained within an accessory gear-box 30 being driven by gearing from the gear-wheels 35, 42 on the shafts 21, 24 respectively. The governor 31 and pump 33 are driven by the lay-shaft 36 and quill-shaft 37 from the gear 35, and the fuel pump 32 and oil pump 34 are driven by the layshaft 43 and quill-shaft 44 from the gear 42. The gears 35, 42 and gears associated with the lay-shafts 36, 43 are contained within a gear casing 100 which is disposed within the working fluid annulus 102 formed between inner and outer walls 101, 103 of the engine casing portion 12. A circular opening 105 is formed in the gear casing 100 and an axially aligned opening 106 is provided in boss portion 107 of the casing 12. Hollow streamlined section struts 104 are disposed between the walls 101, 103 and a sealing member comprising a double-ended piston 108 is provided, the piston portions 109, 110 being in sealing engagement with the cylindrical openings 105, 106; the intermediate portion 111 of the piston 108 passes through the hollow strut 104. The casing 115 of the accessory device 30 is formed with a boss 114 having a cylindrical bore 113 which is disposed opposite a cylindrical bore 112 in the boss 107 on the engine casing 12. A cylindrical member 116 is in sealing engagement with the two bores 112, 113. The quill shaft 37 extends through the openings 105, 106, 112, 113 and the quill shaft 44 extends through corresponding openings at the other end of the accessory device 30. The accessory device is supported from the engine casing by means of four links, two of which 170, 171 are shown in Fig. 3, the links being connected by pivot pins 173 to the bosses 107 on the engine casing 12 and by pivot pins 174 to the accessory casing 115. The link 170 is locked by means of a pin 176 to prevent swinging motion of the accessory device casing. Alternatively, one or more of the struts may be freely hinged at both ends while one or more others may be freely hinged only to the engine casing or to the accessory device.