Method of scavenging a two-stoke reverse-flow scavenged engine, and engine working according to this method

摘要

1. A method of scavenging a two-stroke reverse-flow scavenged engine comprising a piston-controlled exhaust passage and two or more primary as well as secondary scavenge passages on either side of the said exhaust passage, through which the fresh charge is delivered to the cylinder by means of a crankcase pump, a flow being generated at the beginning of the scavenging process by the primary scavenge passages located on either side of the exhaust passage in the immediate vicinity of the latter, which will prevent the fresh charge from entering the exhaust passage, wherein during the downward stroke of the piston the intake ports of the two or more primary scavenge passages are uncovered at a time when the pressure in the cylinder still is higher than in the crankcase, inducing the exhaust gas to flow into said scavenge passages and to force back the fresh charge contained therein without entering the crankcase itself, and wherein upon a drop of the pressure in the cylinder below the pressure level in the crankcase a connection is established between the primary scavenge passages and the crankcase, the intake ports of the two or more secondary scavenge passages being uncovered at the same time, such that the cylinder is scavenged and filled with fresh charge, the exhaust gas admitted into the primary scavenge passages before being discharged again due to a reversal of pressures, forming a barrier against the escape of fresh charge through the exhaust port, upon which the fresh charge will be discharged through the said primary scavenge passages.