A TWO-STROKE INTERNAL COMBUSTION ENGINE WITH VARIABLE COMPRESSION RATIO AND AN EXHAUST PORT SHUTTER AND A METHOD OF OPERATING SUCH AN ENGINE

摘要

The invention relates to a two- stroke internal combustion engine and more particularly to an arrangement for varying the compression ratio of such and the area of an exhaust port of a cylinder of such. There is described a two- stroke internal combustion engine comprising at least one piston (19) reciprocable within a cylinder (20), an exhaust port (23) allowing communication of the cylinder (20) with an exhaust passage (24), which port is opened and closed by the piston (19) during the reciprocal motion thereof, moveable shutter means (1) for varying the effective area of the exhaust port (23), which shutter means (1) varies the effective area cyclically in a timed relationship to the reciprocal motion of the piston (19) within the cylinder (20), a compression ratio variation mechanism for varying a compression ratio of the cylinder (20), sensor means (12) for measuring one or more operating characteristics of the engine and for generating signals corresponding thereto, and a control unit (11) which processes the signals generated by the sensor means (12) and controls the motion of the shutter means (1) accordingly and controls the compression ratio variation mechanism to vary the compression ratio of the cylinder (20); wherein the engine can operate with a compression ratio in the range 30:1 to 50:1.