Patent ID: 7469666
Filing Date: 2008-12-30
Classification: F02B

Abstract:
1. A crankcase scavenged two-stroke engine ( 1 ) comprising a cylinder ( 15 ) including scavenging ports ( 31 , 31 ′) and at least one exhaust port, a piston ( 13 ), a connecting rod ( 17 ), a crankshaft ( 18 ) and a generally sealed crankcase ( 16 ) for inducting a fuel/air mixture from a fuel dosage means ( 37 ), the crankcase ( 16 ) being connected to the scavenging ports ( 31 , 31 ′) by means of transfer ducts ( 3 , 3 ′) for inducting pure air let in from connecting ports ( 8 , 8 ′) near the scavenging ports ( 31 , 31 ′) in the cylinder ( 15 ), the transfer duct ( 3 , 3 ′) volume being less than 20% of a volume swept by the piston ( 13 ) during an entire revolution of the crankshaft ( 18 ), recesses ( 10 , 10 ′) formed in an outer periphery of the piston ( 13 ), said recesses ( 10 , 10 ′) co-operating with the connecting ports ( 8 , 8 ′) in the cylinder wall for controlling the filling of the transfer ducts ( 3 , 3 ′) with air, an inlet tube ( 22 ) formed in the cylinder wall for supplying the air/fuel mixture, said inlet tube ( 22 ) being connected to the crankcase ( 16 ) and covered by the piston ( 13 ) as the piston ( 13 ) is in the lower position, and open to the crankcase ( 16 ) as the piston ( 13 ) is in the higher position.