Patent ID: 6367432
Filing Date: 2002-04-09
Classification: F02B

Abstract:
A two-stroke cycle internal combustion engine, comprisinga cylinder and a piston defining a combustion actuating chamber; a crankcase below the piston and defining a crank chamber; and a SchnÃ¼rle-type scavenging system that includes an exhaust port, a pair of first scavenging passageways communicating the combustion actuating chamber with the crank chamber and disposed closer to the exhaust port, the first scavenging passageways being disposed symmetrically with respect to a longitudinal plane that bisects the exhaust port, a pair of second scavenging passageways communicating the combustion actuating chamber with the crank chamber and disposed farther from the exhaust port, the second scavenging passageways being disposed symmetrically with respect to the longitudinal plane, an air passageway for introducing air into the first scavenging passageways, and an air-fuel mixture passageway for introducing an air-fuel mixture from an air-fuel mixture-generating device into the crank chamber, and wherein the scavenging system is configured such that during a descending stroke of the piston, the exhaust port opens first, a first scavenging port formed at a downstream end of each first scavenging passageway opens after the exhaust port opens, and a moment later, a second scavenging port disposed at a downstream end of each second scavenging passageway opens, whereby air is introduced into the combustion actuating chamber from each first scavenging port prior to the introduction of the air-fuel mixture into the combustion actuating chamber from each second scavenging port.