Patent ID: 8141536

Claim:
An air cleaner to be removably attached to a stratified-scavenging two-stroke internal combustion gasoline engine having: a scavenging window formed into an inner wall of a cylinder; a scavenging channel making communication between said scavenging window and a crank chamber; an exhaust port formed into the inner wall of the cylinder; an air passage communicating with said scavenging channel and feeding the scavenging channel with fuel-free air; and an air-fuel mixture passage for feeding the crank chamber with air-fuel mixture, wherein the air-fuel mixture in said crank chamber is pre-compressed by a descending movement of a piston in an expansion stroke thereof, and the fuel-free air is forced into a combustion chamber through said scavenging window in a scavenging stroke to stratified-scavenge the combustion chamber, wherein the air cleaner comprises: an air cleaner element for cleaning air; a first air opening for supplying said air passage of the engine with air cleaned by said air cleaner element; a second air opening for supplying said air-fuel mixture passage of the engine with air cleaned by said air cleaner element: and a guide member for guiding a back-flow of the fuel-free air toward a vicinity of the second air opening, said back flow of the fuel-free air flowing back into the cleaner through said first air opening after a back flow of the air-fuel mixture flows back into the cleaner through said second air opening during normal operation of the engine, and said back flow of the fuel-free air guided toward the vicinity of the second air opening acting to detain the back flow of the air-fuel mixture once entering into the cleaner element near the second air opening until said back flow of the air-fuel mixture returns into the air-fuel mixture passage through the second air opening.