Abstract: A two-cycle engine including first set of passages formed outside a cylinder connecting a first crank case with scavenging ports for feeding air-fuel mixtures from the first crank case to the cylinder, second set of passages formed outside the cylinder connecting a second crank case with the scavenging ports for feeding air-fuel mixtures from the second crank case to the cylinder, and scavenging gas merging chamber cooperative with the first and second sets of passages and located upstream of the scavenging ports for restricting flow of air-fuel mixtures in vicinity of the scavenging ports. First and second pistons are mounted in opposed relation to each other in the cylinder, the first piston opening and closing an exhaust port and the second piston opening and closing the scavenging ports.

Abstract: In a uniflow, double-opposed piston type two-cycle internal combustion engine of the type having first and second crank chambers attached to the ends of a cylinder, first and second pistons disposed in the first and second crank chambers, respectively, and slidably fitted into the cylinder so as to move toward and away from each other, an exhaust port formed through the cylinder wall and opened and closed by the first piston, and a plurality of scavenging ports formed through the cylinder wall and opened and closed by the second piston, an improvement comprising means for feeding the rich air-fuel mixture to some of the scavenging ports, means for feeding the lean air-fuel mixture or the air to the remaining scavenging ports, and the lean mixture or air scavenging ports being uncovered and opened earlier than the rich mixture scavenging ports, whereby the scavenging efficiency may be improved and the amount of air-fuel mixture escaping through the exhaust port together with the combustion products may be mini