Two-cycle engine

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. The scavenging ports are formed substantially tangentially of the cylinder in a plane normal to the latter, so charges of mixtures gently introduced into the cylinder flow along the top of the second piston in vortical form and the mixtures thus introduced and burned gases remaining in the cylinder are arranged in stratified relation. Fuel in the mixtures in the boundary of the two stratified masses is heated by the heat of the burned gases and the heat caused by the compression stroke of the pistons and has its temperature raised producing radicals of C.sub.2, CH, CHO, OOH and H. These radicals provide multitude of sources of ignitiion enabling compression-ignition of the mixtures to be effected.