Abstract: 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.

Abstract: 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.

Abstract: A two-stroke engine is provided that has a cylinder, in which a combustion chamber is formed, and a piston, which delimits the combustion chamber and which drives a crankshaft rotatably mounted in a crankcase. The piston controls an inlet window for fuel/air mixture into the crankcase interior. A flow guide element is arranged in the crankcase interior which extends adjacent to the inlet window. The flow guide element has at least one first inflow surface by which at least a first partial quantity of the fuel/air mixture flowing in through the inlet window is diverted in the direction of the crankshaft.

Abstract: A two-stroke engine is provided that has a cylinder, in which a combustion chamber is formed, and a piston, which delimits the combustion chamber and which drives a crankshaft rotatably mounted in a crankcase. The piston controls an inlet window for fuel/air mixture into the crankcase interior. A flow guide element is arranged in the crankcase interior which extends adjacent to the inlet window. The flow guide element has at least one first inflow surface by which at least a first partial quantity of the fuel/air mixture flowing in through the inlet window is diverted in the direction of the crankshaft.

Abstract: To monitor a degree of attentiveness for a driver of a vehicle, a period is determined on the basis of a speed of the vehicle. It is determined whether an eyelid closed time and/or an eyelid closing time of the driver exceeds the period.