A mixture-lubricated four stroke engine has a cylinder in which a combustion chamber is formed. The combustion chamber is delimited by a piston which is mounted movably in the cylinder. The engine has an intake channel which discharges into the combustion chamber via an inlet opening controlled by an inlet valve. A mixture formation unit includes at least one fuel opening which discharges into the intake channel. For the lubrication of the crankcase interior, a flow connection connects the intake channel to the crankcase interior via a connecting opening which discharges into the intake channel downstream of the mixture formation unit. The fuel quantity is controlled by a fuel valve. A control unit is configured to activate the fuel valve in a manner dependent on the position of the crankshaft such that the fuel valve is opened at least also during a part of the compression stroke.

Internal combustion engines having a split crankshaft are disclosed. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The pistons also may have a domed piston head with depressions thereon to facilitate the movement of air/charge in the cylinder. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves. The engines may use the pumping motion of the engine piston to supercharge the cylinder with air/charge. The engines also may operate in an inverted orientation in which the piston is closer to the local gravitationally dominant terrestrial body's center of gravity at top dead center position than at bottom dead center position.

Internal combustion engines having a split crankshaft are disclosed. The engines may also have non-circular, preferably rectangular, cross-section pistons and cylinders. The pistons may include a skirt with a field of pockets that provide a ringless, non-lubricated, seal equivalent. The pistons also may have a domed piston head with depressions thereon to facilitate the movement of air/charge in the cylinder. The engines also may use multi-stage poppet valves in lieu of conventional poppet valves. The engines may use the pumping motion of the engine piston to supercharge the cylinder with air/charge. The engines also may operate in an inverted orientation in which the piston is closer to the local gravitationally dominant terrestrial body's center of gravity at top dead center position than at bottom dead center position.

Apparatuses, systems and methods for utilizing crankcase compression air to effect forced air induction (i.e. boost) into the combustion chamber of an internal combustion engine is provided. In some embodiments, the apparatuses are a supercharger apparatus that is attached to an existing engine. In other embodiments, the supercharger components are located within the structure of a novel engine itself. An embodiment of the apparatus includes a conduit that includes three inlets: 1) an inlet that is capable of being placed in fluidic communication with the crankcase chamber of an engine; 2) an inlet that is capable of being placed in fluidic communication with an intake to a combustion chamber of the engine; and 3) an inlet in fluidic communication with the atmosphere.

Apparatuses, systems and methods for utilizing crankcase compression air to effect forced air induction (i.e. boost) into the combustion chamber of an internal combustion engine is provided. In some embodiments, the apparatuses are a supercharger apparatus that is attached to an existing engine. In other embodiments, the supercharger components are located within the structure of a novel engine itself. An embodiment of the apparatus includes a conduit that includes three inlets: 1) an inlet that is capable of being placed in fluidic communication with the crankcase chamber of an engine; 2) an inlet that is capable of being placed in fluidic communication with an intake to a combustion chamber of the engine; and 3) an inlet in fluidic communication with the atmosphere.

A mixture-lubricated four-stroke engine has a cylinder and a piston. On the piston, at least one piston ring is arranged. Between valve drive chamber and crankcase interior, at least one first channel is arranged. The first opening of the first channel lies in the bottom dead center position of the piston below each piston ring. At the first opening, the first channel defines a first middle flow direction for mixture flowing into the crankcase interior. The first middle flow direction extends inclined towards the combustion chamber and in a viewing direction perpendicular to the cylinder longitudinal plane intersects the longitudinal center axis above the first opening of the first channel.

A mixture-lubricated four-stroke engine has a cylinder and a piston. On the piston, at least one piston ring is arranged. Between valve drive chamber and crankcase interior, at least one first channel is arranged. The first opening of the first channel lies in the bottom dead center position of the piston below each piston ring. At the first opening, the first channel defines a first middle flow direction for mixture flowing into the crankcase interior. The first middle flow direction extends inclined towards the combustion chamber and in a viewing direction perpendicular to the cylinder longitudinal plane intersects the longitudinal center axis above the first opening of the first channel.

Apparatuses, systems and methods for utilizing crankcase compression air to effect forced air induction (i.e. boost) into the combustion chamber of an internal combustion engine is provided. In some embodiments, the apparatuses are a supercharger apparatus that is attached to an existing engine. In other embodiments, the supercharger components are located within the structure of a novel engine itself. An embodiment of the apparatus includes a conduit that includes three inlets: 1) an inlet that is capable of being placed in fluidic communication with the crankcase chamber of an engine; 2) an inlet that is capable of being placed in fluidic communication with an intake to a combustion chamber of the engine; and 3) an inlet in fluidic communication with the atmosphere.

Apparatuses, systems and methods for utilizing crankcase compression air to effect forced air induction (i.e. boost) into the combustion chamber of an internal combustion engine is provided. In some embodiments, the apparatuses are a supercharger apparatus that is attached to an existing engine. In other embodiments, the supercharger components are located within the structure of a novel engine itself. An embodiment of the apparatus includes a conduit that includes three inlets: 1) an inlet that is capable of being placed in fluidic communication with the crankcase chamber of an engine; 2) an inlet that is capable of being placed in fluidic communication with an intake to a combustion chamber of the engine; and 3) an inlet in fluidic communication with the atmosphere.

A mixture-lubricated four stroke engine has a cylinder in which a combustion chamber is formed. The combustion chamber is delimited by a piston which is mounted movably in the cylinder. The engine has an intake channel which discharges into the combustion chamber via an inlet opening controlled by an inlet valve. A mixture formation unit includes at least one fuel opening which discharges into the intake channel. For the lubrication of the crankcase interior, a flow connection connects the intake channel to the crankcase interior via a connecting opening which discharges into the intake channel downstream of the mixture formation unit. The fuel quantity is controlled by a fuel valve. A control unit is configured to activate the fuel valve in a manner dependent on the position of the crankshaft such that the fuel valve is opened at least also during a part of the compression stroke.