GB431687A - Improvements in and relating to motor driven propeller units - Google Patents

Abstract

431,687. Two - stroke and four - stroke engines. SCOTT, B. D., Camp, Miserden, near Stroud, Gloucestershire. Jan. 8, 1934, No. 689. [Classes 7 (ii) and 7 (vi)] [See also Group XXXIII] An aircraft engine has one or more pairs of cylinders 41, 42, provided with a common combustion chamber 43, and pistons connected to drive parallel crankshafts 48, 49, in opposite directions. The crank - shafts are geared together by wheels 50, 51, Fig. 1, and to coaxial propeller shafts 16, 17, by wheels 50 ... 53. The exhaust 21, 22 from the engines act on turbines 24, 25 before passing to atmosphere, the centre of the turbines 26, 27 injecting air at 29, 30 to cool the cylinders or supply air for supercharging. The cooling fins 82, Fig. 2, of the cylinders are enclosed in a casing 28 and alternate fins are gapped to produce a labyrinth course for the cooling air which is discharged to atmosphere at the bottom of the fins. Each pair of cylinders 41, 42, are inclined and the axes of the crank-shafts 48, 49 are offset from the centre lines of the cylinders toward one another. The inlet and exhaust valves 56, 57 are operated by balanced cams 58, 59, driven at four to one ratio. The cam-shafts 60, 61 are connected by crank-pins 70, 71, Fig. 3, to a cross-frame 63 pivoted eccentrically at 67 to a gear 661 connected by idle wheels 65, 66 to pinions 481, 491 on the crank-shafts. The lower part of the cross-frame 63 is connected at 72, 73 to oil pumps. Auxiliary frames 74, 75 connected to the crank-shafts at 76, 77 drive, by means of connections 78 ... 81, a dynamo, revolution counter or other auxiliary gear. The engine may operate on the two stroke, four stroke as shown, or a modified four stroke cycle. The latter may be effected by providing an additional admission valve having different timing and open for a shorter period. This valve may supply air or mixture for supercharging, an additional fuel valve or an extra fuel jet being provided in the carburetter. Two or more exhaust valves may be used. The engine may operate by compression-ignition.