Patent GB-1128110-A (GB)
Title: Improvements relating to shaft couplings for gas turbine engines
IPC: F01D5/02
Filed: 1966-06-30
Abstract: 1,128,110. Shaft couplings. DAIMLER-BENZ. A.G. 30 June, 1966 [1, July, 1965], No. 29429/66. Heading F2U. [Also in Division F1] A hollow compressor drive turbine shaft 12 and a hollow compressor shaft 11 of a gas turbine engine are coupled in the circumferential direction, for torque transmission, by a coupling piece 42 having internal teeth 43, 44 engaging external teeth 43a, 44a of the shafts 12, 11, and in the axial direction, for axial thrust transmission, by a rotary bayonet device comprising a locking ring 15 which has an external shoulder 25 acted on, through a pressure ring 27, by an internal shoulder 26 of the shaft 12, and is rotatable from a free position to a locking position, by means operated from the turbine end of the coupling, to bring internal teeth 24a thereon into axial alignment with external teeth 20a on a ring 14 fast on the shaft 11. Slight angular displacement is permitted between the axes of the shafts 12, 11, centring being provided by a spherical crowning 21 formed on the ring 14 and engaging the shaft 12. The arrangement permits the accommodation of operating media pipes within the hollow shafts 12, 11. The power turbine is mechanically separated from the compressor drive turbine and drives a hollow power output shaft 19 extending coaxially inside the compressor drive turbine shaft 12 to drive a hollow shaft 40 extending coaxially inside the compressor shaft 11 to drive an airscrew through reduction gearing. The power output shaft 19 is used to operate the rotary bayonet device. The power output shaft 19 is centred on, and connected by teeth 39, 38 to, a coupling piece 37 fast on the shaft 40. Circumferential locking and unlocking movement of the locking ring 15 with respect to the shaft 12 is limited by engagement of inwardly projecting pins 16 with the ends of circumferentially spaced grooves 29 in the locking ring 15. A securing sleeve 17 has internal teeth 32 engaging external teeth 28 on the locking ring 15 and has, at its front end, circumferentially spaced pairs of open ended slots (30), one and the other of each pair respectively co-operating with one of the pins 16 in the locked and unlocked circumferential positions of the locking ring 15. The securing sleeve 17 is forwardly urged by a spring 18 reacting on a sleeve 46 which is fast with the shaft 12 and abuts or has integral therewith a spacer sleeve 48 having a front edge 48a limiting rearward movement of the sleeve 17. In operation, to unlock the device from the locked position shown the power output shaft 19 is drawn back in the rearward direction X to engage external teeth 34 thereon with internal teeth 33 of the securing sleeve 17 and at the same time abut and act on a flange 35 of the sleeve 17 to withdraw the latter clear of the pins 16 in which position the teeth 39, 38 between the shafts 19, 40 disengage. The actual unlocking is then by turning the shaft 19 until the teeth 24a of the locking ring 15 are opposite the. spaces between teeth 20a of the ring 14. The securing sleeve 17 is then allowed to be spring returned forwardly (direction Y), the other (unlocked) one of each pair of slots (30) then co-operating with a pin 16, so that the shaft 12, together with the securing sleeve 17, spring 18, sleeves 46, 48 and locking ring 15 can be drawn off the ring 14 and the coupling piece 42 in the rearward direction X. In assembly of the engine, the compressor drive and power turbines are first assembled, outside the engine, with the shafts 12, 19 and the parts 27, 15, 16, 17, 18, 46, 48, this assembly then being introduced into the engine in the direction Y.