Internal combustion engine and method for its operation

An internal combustion engine comprising:

• a cylinder comprising a combustion chamber arranged in an interior of the cylinder;
• a piston supported reciprocatingly in the interior of the cylinder and delimiting the combustion chamber;
• a crankcase connected to the cylinder;
• a crankshaft rotatably supported in the crankcase to rotate about an axis of rotation, wherein the piston is operatively connected to the crankshaft so as to drive the crankshaft in rotation;
• at least one first transfer passage providing a flow communication between a crankcase interior of the crankcase and the combustion chamber when the piston is at bottom dead center;
• wherein the at least one first transfer passage comprises a port opening connecting the at least one first transfer passage to the crankcase interior and further comprises at least one first transfer port connecting the at least one first transfer passage to the combustion chamber;
• a fuel supply device configured to supply fuel into the at least one first transfer passage at a location between the at least one first transfer port and the port opening;
• wherein the at least one first transfer passage further comprises, in addition to the port opening and the at least one first transfer port, a connecting opening, wherein the at least one first transfer passage is connected to the crankcase interior at the connecting opening;
• a control element configured to control the connecting opening;
• wherein, independent of a rotational position of the crankshaft, the connecting opening is at least partially closed when the internal combustion engine operates at idle, and wherein, independent of the rotational position of the crankshaft, the connecting opening is open when the internal combustion engine operates at full load.

A method for operating an internal combustion engine, wherein the internal combustion engine comprises a cylinder comprising a combustion chamber arranged in an interior of the cylinder;

• a piston supported reciprocatingly in the interior of the cylinder and delimiting the combustion chamber;
• a crankcase connected to the cylinder;
• a crankshaft rotatably supported in the crankcase to rotate about an axis of rotation, wherein the piston is operatively connected to the crankshaft so as to drive the crankshaft in rotation;
• at least one first transfer passage providing a flow communication between a crankcase interior of the crankcase and the combustion chamber when the piston is at bottom dead center, wherein the at least one first transfer passage comprises a port opening connecting the at least one first transfer passage to the crankcase interior and further comprises at least one first transfer port connecting the at least one first transfer passage to the combustion chamber;
• a fuel supply device configured to supply fuel into the at least one first transfer passage at a location between the at least one first transfer port and the port opening;
• the method comprising:
• providing, in addition to the port opening and the at least one first transfer port, the at least one first transfer passage with a connecting opening and connect the at least one first transfer passage to the crankcase interior at the connecting opening;
• providing a control element configured to control the connecting opening, wherein the control element comprises a first control position that opens a flow cross section of the connecting opening and further comprises a second control position that at least partially closes off the flow cross-section of the connecting opening;
• adjusting the control element between the first control position and the second control position, independent of a rotational position of the crankshaft, as a function of an engine speed of the internal combustion engine;
• as a function of a position of a throttle element of the internal combustion engine;
• or as a function of the engine speed of the internal combustion engine and the position of the throttle element of the internal combustion engine.