Andreas Stihl Ag Co. Kg

Andreas Stihl Ag & Co.

Klaus Geyer

Heiko Rosskamp

Reinhard Gerhardy

Eberhard Schieber

Steffen Bantle

Martin Kiesner

Hans Nickel

Klaus-Martin Uhl

Jörg Schlossarczyk

Heinrich Leufen

Florian Hoche

Friedrich Hollmeier

Arno Kinnen

Michael Grether

Niels Kunert

Tommy Roitsch

Mohamed Abou-Aly

Michael Dietenberger

Karsten Schmidt

Johannes Alber

Jan Borchardt

Jörg Präger

Jochen Gantert

Frederik Herrmann

David Fallscheer

Erik Ames

Joerg Praeger

Andreas Baehner

Lars Bergmann

Stefan Anspann

Johann-Sebastian Renz

Friedrich Holmeier

Philipp KÜHNLE

A method for operating the two stroke engine provides that the fuel valve is controlled after the starting process in at least a quasi-steady state such that, on the basis of uninterruptedly successive blocks of successive revolutions of the crankshaft, the fuel valve is opened and closed exactly once within each block. Each block includes from two to twenty revolutions of the crankshaft. The fuel valve is opened over a crankshaft angle (&#x3b1;) of more than 360&#xb0; within one block in at least one operating state. A control device is provided for controlling the fuel valve. A quasi-steady state of the two stroke engine is a state in which the throttle element is adjusted by less than 10% of the maximum adjustment of the throttle element over a crankshaft angle (&#x3b1;) of 360&#xb0;.

Method for operating a two stroke engine

A method is for starting a combustion engine having a pull-rope starter. A fuel/air mixture is fed to the engine via an intake channel. The mixture is ignited by a spark plug. The combustion drives the piston downward and drives a crankshaft rotationally. The fuel system has a fuel channel opening into the intake channel. An electric fuel valve is open in its currentless state and closes a fuel channel only when an operating voltage is applied. An electronic control unit actuates the fuel valve and triggers an ignition spark and is utilized by a generator to supply energy to the control unit, the fuel valve and the ignition device. To prevent excessive enriching of the fuel/air mixture during starting, the energy, which is generated at the beginning of the rotation of the crankshaft, is used to first close the fuel valve before the control unit triggers an ignition spark.

Method for starting a combustion engine having a starter apparatus

The invention relates to a method for adapting the composition of a mixture of fuel and combustion air. The mixture is supplied to a combustion chamber of a mixture-lubricated combustion engine in a work apparatus. The fuel is supplied to the combustion engine via a controlled fuel valve. In an operating state (I) of the combustion engine, the quantity of fuel is metered by the fuel valve. For the purpose of adapting the composition of the mixture, the combustion engine is shifted into a special operating state (II) which differs from the normal operating state (I). After starting, the combustion engine is operated in a first rotational speed range (B) for a prespecified operating time (T), wherein, after the prespecified operating time (T) has elapsed, the operating state (II) for adapting the composition of the mixture is initiated by a prespecified user action.

Method for adapting the composition of a mixture of fuel and combustion air

A two stroke engine comprises a cylinder, in which a combustion chamber bounded by a piston is formed, and an intake passage. A carburetor forms a section of the intake passage, within which a throttle element is mounted pivotably, and at least one main fuel opening and at least one idling fuel opening open into the intake passage, which is divided downstream of the carburetor into an air passage and a mixture passage. The idling fuel opening feeds a secondary passage arranged within the mixture passage. In the idling position, the throttle element may be arranged adjacent to the upstream entry opening in the secondary passage, and the throttle element may have an opening which, in the idling position of the throttle element, is arranged in the region of the entry opening and connects the secondary passage to that region of the intake passage located upstream of the throttle element.

Two-stroke engine

An internal combustion engine () has a control arrangement () which regulates at least one control parameter for operating the engine (). The control arrangement () includes a non-volatile memory () and a main memory (). During operation of the engine (), an operating value (x) for the control parameter is continually stored in the non-volatile memory (). When starting the engine (), an initial value for the control parameter is determined. According to at least one criterion, a determination is made as to whether the operating value (x) stored in the non-volatile memory () or a standard value (x) is used as the initial value for the control parameter.

Method for operating an internal combustion engine

In a method for operating an internal combustion engine that has a starter device for starting the internal combustion engine and a device for supplying fuel controlled by a control device, it is determined whether cold start conditions or hot start conditions exist during starting of the internal combustion engine. In at least one operating range, during starting of the internal combustion engine, an engine speed gradient is determined during a slowdown phase of a pull stroke of a starter device and the engine speed gradient is used for determining whether cold start conditions or hot start conditions exist. The fuel quantity to be supplied to the internal combustion engine is controlled based on the determined cold start conditions or hot start conditions.

A manually guided implement having a motor unit and a tool unit driven by the motor unit. The motor unit includes an internal combustion engine having a carburetor, and a butterfly valve. A throttle acts upon the butterfly valve via a transfer mechanism. A speed regulator is provided for the internal combustion engine. The transfer mechanism is divided into two transfer portions. The speed regulator is a mechanical speed regulator and is disposed between two transfer portions such that the throttle, via the first transfer portion associated therewith, as well as the speed regulator together act upon the second transfer portion, which is associated with the butterfly valve, whereby as its speed increases, the speed regulator effects a closing of the butterfly valve.

Manually guided implement

The invention is directed to a method for operating a two-stroke engine having a cylinder in which a combustion chamber is formed and which includes devices for metering fuel and supplying combustion air as well as an ignition device for igniting a mixture in the combustion chamber. In the method, fuel and combustion air are supplied to the engine and the mixture in the combustion chamber is ignited. The combustion chamber is delimited by a piston which drives a crankshaft rotatably journalled in a crankcase. A control is provided which controls the metering of fuel and the ignition of the mixture in the combustion chamber. In the method, the two-stroke engine is controlled in at least one operating state so that the number of combustions is less than the number of revolutions of the crankshaft in the same time interval.

Method of operating a single cylinder two-stroke engine

An intake device having an intake channel that includes an intake channel section is provided. A butterfly valve is pivotably mounted in the intake channel section. A dividing wall is disposed downstream of the butterfly valve and divides the intake channel section into an air duct and a mixture duct. The air duct has a flow cross-section that is greater than the flow cross-section of the mixture duct. A fuel jet opens into the mixture duct.

Intake device

A carburetor for an internal combustion engine includes an intake channel section () as well as a throttle element journalled in the intake channel section (). The throttle element is adjustable between a full-load position () and an idle position (). A pump () is provided for additional fuel metering and this pump includes a pumping chamber () and a pump piston () guided in the pumping chamber (). The position of the pump piston () is coupled to the position of the throttle element. To ensure an optimal supply of the internal combustion engine with fuel in each operating state, the pump piston () is so coupled to the throttle element that fuel is pumped from the pumping chamber () into the intake channel section () when there is a displacement of the throttle element from the full throttle position () into the idle position ().

Carburetor

The invention is directed to an ignition circuit for a two-stroke engine in a portable handheld work apparatus. A spark plug () is connected via a switch () to a voltage source (). The ignition switch () is actuated by an electronic control circuit () which closes the ignition switch () in dependence upon the crankshaft angle and additional operating parameters such as the rpm of the engine () in order to trigger an ignition spark per revolution of the crankshaft (). To limit rpm, the ignition switch () is held open when a pregiven end rpm is exceeded in order to suppress an ignition spark over at least one crankshaft revolution. In order to prevent that additional vibrations are excited by the limiting of rpm, the ignition switch () is closed after an end rpm is exceeded in accordance with the random principle and in dependence upon the position of the crankshaft () in such a manner that an ignition spark, which corresponds to a crankshaft revolution, is triggered in accordance with the random principle.

Ignition circuit having RPM limitation for an internal combustion engine

A method of limiting the maximum speed of a two-cycle engine in a manually-guided implement such as a hedge trimmer is provided. Via a unit for controlling the ignition time point in a crankshaft angular range prior to the upper dead center position of a reciprocating piston, the ignition is interfered with above an operational speed to keep the speed below the maximum speed. To ensure a rapid onset of the speed regulation along with good exhaust gas values, in the range between the operational speed and the maximum speed, the ignition time point is shifted in the direction toward the upper dead center position of the piston in such a way that in the vicinity of the maximum speed, the ignition time point is close to the upper dead center position of the piston and the engine output is reduced to a prescribed value that corresponds approximately to the frictional horsepower for the driving of the tool.

Maximum speed limitation for a two-cycle engine

A two-stroke engine is provided for a manually-guided implement. Formed in a cylinder is a combustion chamber that is delimited by a reciprocating piston that drives a crankshaft via a connecting rod. An outlet is provided for withdrawing exhaust gases out of the combustion chamber, and an inlet is provided for supplying fresh mixture to the combustion chamber. The inlet forms one end of a storage channel, the other end of which opens out via a window controlled by the piston into the crankcase. Via a fuel-supplying mixture channel, the storage channel is connected with a fuel supply. Combustion air is supplied to the crankcase via a crankcase inlet, with the combustion air being conveyed into the combustion chamber via a transfer channel and a transfer window. The storage channel is connected to the mixture channel via a connecting channel that is controlled by the piston.

Two-stroke engine in a portable, manually-guided implement

A two-stroke engine in a hand-held working tool such as a motor chainsaw has a combustion chamber delimited by a piston which drives a crankshaft. An outlet for removing exhaust gases from the combustion chamber and an intake for supplying fresh mixture to the combustion chamber are provided. A storage duct opens into the intake and the crankcase and is connected with a carburetor. Combustion air flows via a crankcase intake and a transfer passage into the combustion chamber. For providing good power development with good exhaust emission values under all operating conditions, the flow cross-section of the mixture-forming channel leading to the storage duct is smaller by more than one half than the flow cross-section of the intake passage leading to the crankcase intake. During idle, the fuel required for operation is supplied substantially exclusively via the mixture-forming channel leading to the storage duct.

Two-stroke engine with storage duct

The invention is directed to a method for operating a two-stroke engine in a portable handheld work apparatus. The engine includes a cylinder ( ) and a combustion chamber ( ) which is delimited by a reciprocating piston ( ). The combustion chamber includes an outlet ( ) discharging exhaust gases and an inlet ( ) of a storage channel ( ). The inlet ( ) lies approximately opposite the outlet ( ) and the other end of storage channel ( ) opens via a controlled end ( ) into the crankcase ( ). Between its ends, the storage channel ( ) is connected to a first fuel metering device ( ) of a first fuel path; whereas, the crankcase ( ) has a crankcase inlet ( ) which is connected to a second fuel metering device ( ) of a second fuel path. In the case of an acceleration, additional fuel is metered to one or both fuel paths via an acceleration unit ( ). In order to ensure a powerful run-up of the engine in the case of acceleration, the acceleration device ( ) pumps into both fuel paths for an acceleration of the engine.

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Sulzbach, Germany

Klaus Geyer