Pre-Combustion Cycle Pressurisation System using a pivoting flap valve

摘要

597142 A two stroke internal combustion engine (1) incorporating an asymmetric exhaust port/transfer port inversion device (2) is disclosed. The asymmetric exhaust port/transfer port inversion device is characterised in that it includes a hollow flap valve (100) adapted to pivot about a hollow pivot shaft (101) between a closed position and an open position wherein pivoting the device to the open position as the piston (3) begins the compression stroke allows the transfer of air to continue after the leading edge of the piston has closed off the exhaust port (105) thereby advancing the timing of the exhaust port closing and extending the duration of air transfer from the crankcase primary compression chamber (103).