Patent ID: 6978744
Filing Date: 2005-12-27
Classification: F02B

Abstract:
1. A two-cycle combustion engine having an air scavenging system, which comprises: a crankcase having a crank chamber defined; an cylinder block defining therein a combustion chamber and mounted on the crankcase; first and second scavenge passages each communicating between the combustion chamber and the crank chamber; an air supply passage for supplying air; an air introducing passage for introducing the air from the air supply passage towards the second scavenge passage; a reed valve disposed in the air supply passage; and an air-fuel mixture supply passage for supplying an air-fuel mixture into the crank chamber, wherein the second scavenge passage is positioned at a location nearer to an exhaust port than the first scavenge passage and the air introducing passage is formed in the cylinder block so as to introduce the air from the air supply passage into the second scavenge passage by way of a radially outer portion of the first scavenge passage, wherein a recess defining the air introducing passage is formed in the cylinder block together with casting of the cylinder block, and wherein during an intake and compression stroke, the air from the air supply passage is introduced into the second scavenge passage through the reed valve and the air-fuel mixture from the air-fuel mixture supply passage is introduced into the crank chamber, and during a scavenge stroke, supply of the air within the second scavenge passage into the combustion chamber is initiated prior to initiation of supply of the air-fuel mixture within the crank chamber into the combustion chamber through the first scavenge passage.