Andreas Stihl Ag & Co.

Andreas Stihl

Other

Andreas Stihl Ag Co. Kg

Hans Holderle

Werner Vonderau

Jurgen Wolf

Helmut Zimmermann

Johannes Menzel

Reinhard Gerhardy

Axel Klimmek

Andreas Bähner

Michael Joos

Andreas Lingen

Horst Denner

Matthias Hehnke

Bernd Kn&ouml;dler

Joachim Baumhauer

Horst Eckhart

Stefan Kummermehr

Armin Speckens

Roger Simons

A two-stroke engine () has a combustion chamber () disposed in a cylinder (). The combustion chamber () is delimited by a reciprocating piston (). The piston () drives a crankshaft () via a connecting rod () and the crankshaft () is rotatably journalled in a crankcase (). The two-stroke engine () has an intake channel () for the supply of fuel into the crankcase (), an outlet () for exhaust gases from the combustion chamber () and an air channel () for the supply of substantially fuel-free air. A throttle element () is mounted in the air channel (). At pregiven positions of the piston (), the crankcase () is connected via at least one transfer channel () to the combustion chamber (). In order to prevent air from being drawn by suction into the air channel because of leakages during idle or at low rpm, a fluid connection is provided between the air channel () downstream of the throttle element () and the crankcase () for underpressure compensation which connection is present at least partially for a position of the piston from 90&#xb0; ahead of bottom dead center to 90&#xb0; after bottom dead center. A connection between the crankcase () and the intake channel () can be provided in lieu of, or in addition to, the connection to the air channel ().

Two-stroke engine

The invention is directed to an arrangement of an air filter (,) and a membrane carburetor (,). The membrane carburetor (,) has an intake channel section (,) configured in the carburetor housing (,) and fuel-conducting channels (,) open into the intake channel section (,). The channels (,) are supplied from a fuel-filled control chamber (,) which is configured in the carburetor housing (,). The control chamber (,) is partitioned from a compensation chamber (,) via a control membrane (,). The compensation chamber (,) communicates with the housing (,) of the air filter (,) via a compensation channel (,) downstream of an air filter element (,). The air filter housing (,) engages over the membrane carburetor (,) essentially on the side of the compensation chamber (,) and the clean chamber (,) of the air filter housing (,) communicates with the intake channel section via a connecting stub (,) which lies approximately at right angles to the intake channel section (,). The connecting stub (,) is used as a connection between the clean chamber (,) of the air filter (,) and a flow space (,) mounted forward of the intake channel section (,) in order to ensure a reliable compensation where available space is tight. The volume of the flow space (,) is greater than the volume of the connecting stub (,) and the compensation channel (,) branches away from the flow space (,).

Arrangement of an air filter and a membrane carburetor

The invention relates to a membrane carburetor for an internal combustion engine in a portable handheld work apparatus such as a motor-driven chain saw. A throttle flap is arranged in the intake channel for the combustion air. The throttle flap is pivotally journalled downstream of a venturi section of the intake channel. A main nozzle for supplying fuel from a fuel-filled control chamber of the carburetor is provided in the region of the venturi section. The control chamber is delimited by a membrane which actuates a control valve controlling the fuel inflow into the control chamber. The main nozzle includes a check valve which includes a valve seat with a valve platelet assigned thereto. In order to avoid a dripping of the main nozzle even under unfavorable operating conditions, a sieve platelet is provided which effects an additional capillary sealing of the main nozzle during idle. The sieve platelet substantially completely covers the outlet cross section of the main nozzle downstream of the check valve.

Membrane carburetor for a portable handheld work apparatus

The invention is directed to a membrane fuel pump for an internal combustion engine equipped with a membrane carburetor. The engine is that of a working apparatus and especially a handheld portable tool such as a motor-driven chain saw or the like. The membrane pump includes a drive chamber charged with the pressure inside the crankcase of the engine and a pump chamber separated from the drive chamber by a membrane. The pump chamber is connected at its suction end to a fuel tank via a first check valve and is connected to a pressure controller of the membrane carburetor at its pressure end via a second check valve. The pressure end of the membrane pump is connected with the suction end thereof via a bypass and a throttle is mounted in this bypass. With the throttle bypass between the pressure end and the suction end, the pumped volume is reduced at idle and the pump pressure is smoothed. Disturbances at the membrane carburetor are avoided.

Membrane fuel pump with pulse dampener

Disturbances can occur in handheld portable tools driven by internal combustion engines because the idle-nozzle system and the main-nozzle system influence each other. The carburetor of the invention prevents this disturbing influence and provides a control of the engine which is proportional to speed. The carburetor includes a control member which closes off the main nozzle during idle operation and the idle nozzle during operation under load in dependence upon the position of the throttle flap.

Carburetor for an internal combustion engine

A connecting piece interconnects the carburetor and combustion chamber of an internal combustion engine. The fuel-air mixture produced in the carburetor flows to the combustion chamber through the connecting piece in a primary flow direction. A plurality of closely spaced protrusions are provided on the inner wall of the connecting piece and these protrusions are disposed one behind the other and are offset from one another in the primary flow direction of the fuel-air mixture such that the formation of axially parallel channels is avoided. This embodiment prevents the fuel film deposited on the inner wall of the connecting piece from being completely aspirated all at once into the combustion chamber, which would cause a severe overenrichment of the mixture and hence a drop in rpm. Because of the many protrusions, the fuel film that is deposited tears off in the smallest possible pieces when being aspirated, so that only small parts of this film ever reach the combustion chamber at the same time. Fluctuations in the idling rpm are considerably lessened with a connecting piece configured in this manner.

Connecting piece between the carburetor and the combustion chamber of an

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Freiberg, Germany

Hans Holderle