Improvements in air-cooled four-stroke internal combustion engines with rotary valve control

摘要

738,085. Rotary valves; cooling cylinders. N.S.U. WERKE AKT.-GES. Aug. 12, 1952 [Aug. 27, 1951], No. 20247/52. Classes 7(2) and 7(6). A rotary valve m housed in the cylinder head of an air-cooled engine with its axis of rotation extending in the direction of the cylinder axis, is is of cylindrical shape at the end adjacent the piston and is insulated with respect to the cylinder head by an air gap a, and the valve is rigid with a shaft o the smallest diameter of which is between 0À5 and 1 times the cylinder diameter. The valve may be cylindrical in shape or, as shown in Fig. 1, it may have a cylindrical lower portion n sealed by piston-type rings e and a hemispherical upper portion m, the valve port being sealed by a loose bush f forced by cylinder pressure against the valve casing. The valve shaft o, mounted in roller bearings d, p, may have a passage g therein through which cooling air is drawn by fan blades c carried by a hub b shrunk on to the valve shaft, the cooling air flowing through the valve body to passages i, j, k in 'the fan which also forces cooling air over the cylinder cooling ribs u. Vanes v on the cylinder head form guide vanes for the fan. The valve is driven by a shaft q and intermediate gear wheel r.