GB733743A - Improvements in or relating to two-stroke-cycle internal combustion engines - Google Patents

Abstract

733,743. Two-stroke engines ; charge filtering and pumping ; lubricating spray carburetters ; valves. AMERICAN BRAKE SHOE CO. Aug. 19, 1953 [Aug. 29, 1952; Aug. 7, 1953], No. 22856/53. Classes 7(2), 7(3) and 7(6). [Also in Group XXXIV] In a two-stroke crankcase-compression engine, a filter 132, Fig. 8, rotatable with the crankshaft, prevents lubricant entrained in the crankcase gases from passing into the transfer passage 111, which, as shown, communicates with the cylinder through piston ducts 115, 116. The filter 132 comprises felt, &c. secured in the perforated rim 131 of a disc 130. In the two-cylinder spark-ignited engine shown, with crankcase compression of combustible mixture, the arrangement is duplicated, all the exhaust ports 117 delivering to a common pipe 121. The rotatable filter may take several forms. A sealing ring, as 183, Fig. 21, may be provided on the crankcase, and the felt replaced by a corrugated screen 182 or dispensed with, when the rim perforations are replaced by thin axial slots which alone provide filtering. In Fig. 22, instead of the usual piston-controlled crankcase inlet, an inlet 204 is controlled by the disc 206 of the filter 200, which disc has an arcuate valve slot and, over the extent of this slot only, has radial charge-inducing vanes. In Fig. 1 (not shown), the filter is in a cylindrical box journalled at one end about the centrally disposed entry of the transfer passage and entrained by a crankpin extension and comprises a felt &c. washer covering perforations in the wall and journalled end of the box. With diesel engines, or engines having liquid fuel drawn into the transfer passage, air is drawn into the crankcase through a piston-controlled port 243, Fig. 26, having an entry 244 provided with a filter 267 and throttle valve 245. As shown, liquid fuel is supplied to the transfer passage 268 through a jet 260 supplied via a check valve 256 from a float chamber 249 interconnected with the entry 244 by a pipe 264 for pressure equalization. In Fig. 25 (not shown) a similar arrangement but without such pressure equalization has a fuel nozzle delivering axially at the throat of a Venturi in the transfer passage proper. Lubrication. In Fig. 8, under the action of crankcase pressure variation, separate reservoirs 96 fed from sumps 89 via narrow bores 95 supply lubricant to crankcase moving parts via conduits 103 having check valves. The sumps 89 have screens 91, and crankshaft fingers 127 afford additional lubrication by splash. A pipe 211, Fig. 22, may replace the bore 95. In Fig. 18 (not shown), the lubricant from the reservoir is directed via external piping to a cylinder wall bore delivering just below a piston-controlled crankcase inlet.