Patent ID: 7574984
Filing Date: 2009-08-18
Classification: F02B,F02F

Abstract:
1. A crankcase scavenged two-stroke internal combustion engine ( 1 ) having fuel and air mixture inlet period in which a piston ported air passage is arranged between an air inlet ( 2 ) and the upper part of a number of transfer ducts ( 3 , 3 ′), wherein the air passage is arranged from the air inlet ( 2 ) that is equipped with a restriction valve ( 4 ) which is controlled by at least one engine parameter, the air inlet extends via at least one connecting duct ( 6 , 6 ′) to at least one connecting port ( 7 , 7 ′; 8 , 8 ′) in the cylinder wall ( 12 ) of the engine, which is arranged so that the at least one connecting port ( 7 , 7 ′; 8 , 8 ′), in connection with piston positions at the top dead center, is connected with flow paths ( 9 , 9 ′; 10 , 10 ′; 11 , 11 ′) embodied in the piston ( 13 ), which extend to the upper part of a number of transfer ducts ( 3 , 3 ′), and the flow paths in the piston are so arranged that recess ( 9 , 9 ′; 10 , 10 ′, 11 , 11 ′) in the piston that meets respective transfer duct's port ( 31 , 31 ′) is arranged so that the air supply is given an essentially equally long or longer period, counted as crank angle or time, in relation to the fuel and air mixture inlet period.