GB547426A - Improvements in or relating to power plants for aircraft - Google Patents

Abstract

547,426. Power plant ; driving-gear. BRISTOL AEROPLANE CO., Ltd., FEDDEN, A. H. R., OWNER, F. M., THOMAS, F. M., and MANSELL, S. W. Jan. 17, 1941, No. 14691. Divided out of 547,403. [Class 7 (ii)] [Also in Group XXXIII] Two engines placed face to face so that their crankshafts rotate in opposite directions with their axes in line, drive through clutches and bevel gearing two airscrew shafts extending transversely of the crankshafts, means being provided also for uncoupling each airscrew shaft from the gearing, and for permitting overrunning of either crankshaft by the gearing except when it is desired to prevent such overrunning when the engine is running on closed throttle. Two pairs of such engines may be mounted in each wing of an aeroplane, with their crankshafts transverse to the longitudinal axis of the machine, to drive airscrew shafts extending to the leading or both leading and trailing edges of the wing. Two crankshafts 12, 13, Fig. 1, drive two bevel wheels 14, 30, mounted on separate bearings 15, through positive clutches comprising sliding sleeves 17, 31 splined to the shafts 12, 13 and having helical splines engaging the hubs of the bevel wheels 14, 30 so that the sleeves become automatically disengaged should the gearing overrun the shafts. When completely disengaged an enlarged end 28 on each sleeve enters a cylindrical chamber on a member 20 and is held therein by a ball catch 29. The member 20 is splined to the crankshaft and has a cylindrical portion sliding over a fixed cylinder 22. The member 20 carries half of the plates of a plate clutch for coupling frictionally the crankshaft to the corresponding bevel wheel. To engage the clutch, oil under pressure is fed through a duct 23 to a chamber 21 and as the member moves towards the bevel wheel a passage 25 is uncovered by a flange 24 to admit oil to a chamber 27 to force out the corresponding sleeve 17 or 31. As soon as the sleeve engages the hub of the gear wheel it is drawn clear of the member 20 by the action of the helical splines and the oil escapes. Each engine drives an oil pump and the two systems can be connected together so that one engine may be started by the other by maintaining pressure in the chamber 27 of the idle engine and so preventing disengagement of the sleeve. The valve arrangements may be interconnected with the throttle lever so that pressure fluid is only supplied at low throttle settings. The two bevel wheels 14, 30 mesh with bevel wheels 32, 33 flexibly coupled to transverse shafts. Fig. 2 shows the bevel wheel 33 mounted on a sleeve 42 having a cylindrical bearing in a sleeve 48 splined to a sleeve 68 which in turn is splined to a shaft 35 so as to allow of slight relative displacements. A sleeve 43 splined to the sleeve 42 has a flange 45 with teeth 46 normally engaging teeth on a flange 47 on the sleeve 48. The flange 47 forms a piston working in a chamber 50 secured to the flange 45 and by admitting oil under pressure to either side of the flange 47 the sleeve 43 can be displaced to disengage or engage the teeth. A movable hollow valve stem 55 effects the distribution by working in a fixed valve block 57, the pressure fluid passing from a conduit 54 through the interior of the stem and exhausting into the casing. Fig. 4 shows an aeroplane wing with two pairs of engines in sealed casings 78 driving shafts 35 coupled to oppositely rotating propellers 77. Air ducts 79 supply air to the engines, the cooling air passing through chambers 75, 76 and conduits 81 to the trailing edge of the wings. The exhaust pipes 82 discharge into these conduits. The cooling arrangements are as described in Specifications 547,404, 547,405 and 547,406. Alternatively the two engines may be mounted in the fuselage with their crankshafts lying longitudinally and driving airscrews on the wings as described in Specifications 546,630, [Group XXXIII], and 547,403.