Abstract: An externally auto-ignited four-stroke internal combustion engine which includes a combustion chamber disposed in an upper surface of a piston such that, in an upper dead-center position of the piston, the combustion chamber receives almost all of the fuel-air mixture. The combustion chamber includes a planar bottom portion and has a cross-sectional shape of a truncated cone expanding in a direction of the cylinder head. The internal combustion engine also includes a recess or depression provided in the cylinder head and disposed eccentrically with respect to a longitudinal center axis of the cylinder. The depression or recess in the cylinder head has the shape of a truncated cone expanding in a direction of the piston, with a spark plug projecting or penetrating into the recess or depression in the cylinder head.

Abstract: An engine exhaust brake for a motor vehicle operated with an Otto-engine, which upon its engagement causes the closing of the exhaust gas line by means of a throttle device and the opening of the throttle valve controlling the mixture supply; a gas-air mixer is thereby arranged upstream of the throttle valve whose gas supply is controlled by the output stage of a membrane-controlled gas-regulator whose vented side is connected with the atmosphere by way of an air line and preferably also by way of a filter protection; a control valve is also arranged in the air line which is controlled by the engine-brake engaging mechanism and which upon engagement of the engine brake connects the vented side of the output stage of the gas regulator with the engine suction pipe, whose vacuum causes the closing of the gas supply to the gas-air mixer.