AIR SCAVENGING-TYPE TWO-CYCLE ENGINE

摘要

An air scavenging-type two-cycle engine where a bearing of a crankshaft can be lubricated with gas blow-by being controlled by a simple structure. The engine has a first scavenging passage (13) communicating between a combustion chamber (1a) and a crank chamber (2a) through a bearing (81) of a crankshaft (8), a second scavenging passage (14) directly communicating between the combustion chamber (1a) and the crank chamber (2a), a suction chamber (72) formed in a side face of a piston (7), a mixture gas passage (10) through which a mixture gas (M) is sucked into the suction chamber (72), and an air passage (11) through which air (A) is introduced into the crank chamber (2a). In a suction stroke, the mixture gas (M) from the mixture gas passage (10) is introduced into the first scavenging passage (13) through the suction chamber (72), and the air (A) from the air passage (11) is introduced into the crank chamber (2a). In a scavenging stroke, before the mixture gas (M) in the first scavenging passage (13) is introduced into the combustion chamber (1a), introduction of the air (A) in the crank chamber (2a) into the combustion chamber (1a) through the second scavenging passage (14) starts.