Stratified air scavenging in two-stroke engine

Abstract From the Canadian patent

A two-cycle engine has an air inlet in the crankcase and a spiral air-fuel passage encircling the cylinder wall rising from the crankcase to an inlet in the cylinder head to effect cooling of the cylinder. A fuel injection device introduces fuel into the transfer passage. A unidirectional valve admits air and fuel into the cylinder head and curved fins impart a swirling action to the air and fuel to effect a fuel and air stratification. An exhaust passage in the cylinder wall has an adjustable throttle to control directly the outflow of exhaust gases and indirectly the inflow of fresh fuel-air mixture, whereby the power level of the engine is controlled.