Patent ID: 6595168
Filing Date: 2003-07-22
Classification: F02B,F02F,Y02T

Abstract:
An air-preintroduction type two-stroke internal combustion engine, comprising:a cylinder; a piston fittingly inserted into the cylinder for reciprocating movement therein; a crankcase hermetically and contiguously disposed below the cylinder and defining a crank chamber; the crankcase adjoining the cylinder at a mating face; a combustion actuating chamber disposed above and communicating with the cylinder; an exhaust port provided in a sidewall of the cylinder; means for forming an air-fuel mixture; one or more pairs of scavenging passageways, each allowing the combustion actuating chamber to be communicated with the crankcase, symmetrically provided on both sides of a longitudinal section which divides the exhaust port into two equal parts; the scavenging passageways allowing air to be introduced therein; a scavenging port formed at a downstream end of said scavenging passageway; the air-fuel mixture-forming means allowing the air-fuel mixture to be introduced therefrom into the crank chamber; the exhaust port being first opened in the descending stroke of the piston before the scavenging ports are opened; wherein air is introduced via the scavenging passageways into the combustion actuating chamber prior to the introduction of the air-fuel mixture; an air inlet passageway for introducing air into the scavenging passageways provided at the mating face between the cylinder and the crankcase; and wherein the air inlet passageway is an annular passageway formed at an opening downwardly through the lower end portion of the cylinder, the open lower underside of the annular passageway being closed by an upper wall of the crankcase.