To meet stringent emission standards and improve performance of two-stroke crankcase-scavenged engines, the muffler (13) of the engine is provided with mixing means (130, 31) for mixing the exhaust gases (42) resulting from the mixture participating in combustion and gases resulting from scavenging, so that a substantially homogenous gaseous mixture is formed within the muffler (13), and means (81) for sensing oxygen concentration is located in the homogeneous gaseous mixture and are configured to provide an output value to a control unit (80) for controlling supply of fuel to the engine and thereby the air-fuel ratio in the combustion chamber (41). The muffler (13) suitably is provided with a catalytic element (140), preferably a three-way catalyst. The engine (1) preferably is a stratified charge engine.

The present invention uses the exhaust gas of an internal combustion reciprocating engine to drive a turbine. The turbine is position around the cylinder. The turbine is connected to systems that will use the energy to improve the total system efficiency. One such system would be connected to a compressor to create the force induction required for two-stroke engines.

A uniflow-scavenged two-cycle engine includes: a cylinder which has a combustion chamber; a piston; a scavenging chamber that surrounds one end side of the cylinder in the stroke direction of the piston and to which compressed active gas is guided; a scavenging port that is provided in a portion of the cylinder which is positioned in the scavenging chamber and suctions active gas from the scavenging chamber to the combustion chamber in response to a sliding motion of the piston; a fuel injection opening that injects fuel gas into the active gas which is suctioned into the scavenging port; and a fuel injecting valve that opens and closes a fuel supply path through which a fuel tank, communicates with the fuel injection opening, and is disposed in an space isolated from the scavenging chamber.

A uniflow-scavenged two-cycle engine includes: a cylinder which has a combustion chamber; a piston; a scavenging chamber that surrounds one end side of the cylinder in the stroke direction of the piston and to which compressed active gas is guided; a scavenging port that is provided in a portion of the cylinder which is positioned in the scavenging chamber and suctions active gas from the scavenging chamber to the combustion chamber in response to a sliding motion of the piston; a fuel injection opening that injects fuel gas into the active gas which is suctioned into the scavenging port; and a fuel injecting valve that opens and closes a fuel supply path through which a fuel tank, communicates with the fuel injection opening, and is disposed in an space isolated from the scavenging chamber.

A uniflow two-stroke engine, includes: a cylinder receiving a piston such that the piston can reciprocate therein; an exhaust port provided in an upper end part of the cylinder; and a scavenging port that is provided in a lower side wall portion of the cylinder so as to be opened and closed by the piston, wherein a downstream portion of the scavenging port that opens out to the cylinder includes a guide member that gives a downward velocity component to a gas flow entering the cylinder from the scavenging port.

A uniflow two-stroke engine, includes: a cylinder receiving a piston such that the piston can reciprocate therein; an exhaust port provided in an upper end part of the cylinder; and a scavenging port that is provided in a lower side wall portion of the cylinder so as to be opened and closed by the piston, wherein a downstream portion of the scavenging port that opens out to the cylinder includes a guide member that gives a downward velocity component to a gas flow entering the cylinder from the scavenging port.

A method for supercritical diesel combustion combines fumigation and supercritical diesel fuel combustion to effect greater fuel efficiency and reduce exhaust gas pollutants from a compression ignition engine. The invention utilizes the fumigant method by combining two gases (DME and propane) which autoignite prior to the injection of the liquid diesel fuel. This pre-combustion of the fumigant gases combined with the engine's compression of the combustion chamber gases is managed to attain a supercritical combustion chamber environment into which the liquid diesel fuel is injected. This targeted supercritical combustion chamber environment causes the diesel fuel to become a supercritical fluid prior to combustion, resulting in significantly greater efficiency and negligible exhaust gas pollutants resulting from the combustion of the diesel fuel.

A method for supercritical diesel combustion combines fumigation and supercritical diesel fuel combustion to effect greater fuel efficiency and reduce exhaust gas pollutants from a compression ignition engine. The invention utilizes the fumigant method by combining two gases (DME and propane) which autoignite prior to the injection of the liquid diesel fuel. This pre-combustion of the fumigant gases combined with the engine's compression of the combustion chamber gases is managed to attain a supercritical combustion chamber environment into which the liquid diesel fuel is injected. This targeted supercritical combustion chamber environment causes the diesel fuel to become a supercritical fluid prior to combustion, resulting in significantly greater efficiency and negligible exhaust gas pollutants resulting from the combustion of the diesel fuel.

A uniflow scavenging two-cycle engine includes an scavenging port having a swirling guide portion that guides scavenging gas into a cylinder in a direction inclined with respect to a radial direction of the cylinder, and a center guide portion that is provided to be closer to a crank side of the cylinder than the swirling guide portion and guides the scavenging gas further toward the center side of the cylinder than the swirling guide portion. At least a part of the center guide portion faces a piston when the piston is positioned at bottom dead center during the high compression ratio mode, and the center guide portion and the piston do not face each other or an area of facing the piston is smaller than that during the high compression ratio mode when the piston is positioned at bottom dead center during the low compression ratio mode.

A uniflow scavenging two-cycle engine includes an scavenging port having a swirling guide portion that guides scavenging gas into a cylinder in a direction inclined with respect to a radial direction of the cylinder, and a center guide portion that is provided to be closer to a crank side of the cylinder than the swirling guide portion and guides the scavenging gas further toward the center side of the cylinder than the swirling guide portion. At least a part of the center guide portion faces a piston when the piston is positioned at bottom dead center during the high compression ratio mode, and the center guide portion and the piston do not face each other or an area of facing the piston is smaller than that during the high compression ratio mode when the piston is positioned at bottom dead center during the low compression ratio mode.