Andreas Stihl Ag Co. Kg

Predag Ostojic

Andreas Lingen

Andreas Bähner

Andreas Paa

Jörg Amann

Jan Borchardt

Michael Schmid

Nils Kunert

A handheld work apparatus has an internal combustion engine (&#x2033;) and a starter device (). The internal combustion engine has a piston (&#x2033;) which has at least one piston ring (). In order to avoid a delay when starting the engine, at least one recess is provided in the cylinder bore () which bridges the at least one piston ring () in at least one position of the piston (') and which has a distance (n, o, p) to all function openings of the engine (&#x2033;) configured in the cylinder bore (). To reduce the compression in the combustion chamber (), the piston (&#x2032;) has only one piston ring () or two piston rings () are provided having respective piston ring gaps () defining an angle (&#x3b2;) which is up to approximately 45&#xb0;.

Handheld work apparatus

For operating an internal combustion engine with a combustion chamber delimited by a piston driving a crankshaft in a crankcase, with a device for supplying fuel, an ignition device, and an electronic control unit, wherein a correlation between a power output of the internal combustion engine and a lambda value in the combustion chamber is defined by a power output curve that has a first ascending branch, a maximum, and a second descending branch where the lambda value is smaller than 1, the position of an operating point of the internal combustion engine is determined by adjusting the ignition timing to an adjusted ignition timing and evaluating the engine speed reaction caused by the adjusted ignition timing. The supplied fuel quantity is changed as a function of the determined position of the operating point when the determined position of the operating point is not a desired operating point.

Method for operating an internal combustion engine

An internal combustion engine includes a cylinder () wherein a combustion chamber () is formed. The engine also includes devices for metering fuel and combustion air as well as an ignition device for igniting the mixture in the combustion chamber (). A method for operating the internal combustion engine provides that fuel and combustion air are supplied to the engine and the mixture is ignited in the combustion chamber (). The combustion chamber () is delimited by a piston () which drives a crankshaft () rotatably journalled in a crankcase (). A control is provided which controls the supply of fuel and the ignition of the mixture in the combustion chamber (). The internal combustion engine is so controlled in at least one operating state that the number of combustions is less than the number of engine cycles in the same time span. To avoid the formation of self ignitions, the operating state is a high rpm range wherein the rpm lies above the rated rpm and below the rpm in a regulating range.

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Freiberg, Germany

Predag Ostojic