Andreas Stihl Ag Co. Kg

Michael Grether

Niels Kunert

Stefan Kummermehr

Bernd Engel

Robert Köhli

Klaus Geyer

Michael Raffenberg

Tommy Roitsch

Robert Koehli

Wolfgang Kienzle

Johannes Alber

Christian Schlecker

Richard Wirt

Lutz Volckart

Daisuke Suzuki

Jürgen Aupperle

Hannes Frank

Malte Hartmann

Philipp KÜHNLE

A two-stroke engine possesses a cylinder, in the cylinder bore of which a combustion chamber is formed. The combustion chamber is bounded by a reciprocating piston, which drives a crankshaft rotatably mounted in a crankcase. A crankcase interior is fluidically connected to the combustion chamber across at least one transfer channel in at least one position of the piston. The at least one transfer channel emerges with a discharge opening in the crankcase interior and with at least one transfer window on the cylinder bore. It is proposed that all transfer channels have an average length as measured from the discharge opening to the transfer window, the average length being at least 1.5 in relation to the stroke, and that the volume of the crankcase interior including all transfer channels is at most 3.1 in relation to the piston displacement.

Two-stroke engine

A fuel feed unit has a base body with an intake channel section, into which a fuel opening opens. A partition wall section divides the intake channel section into a mixture channel and an air channel. The wall section has a recess in which the throttle flap at least partially lies in an end position. The wall section has, upstream of the recess, a continuous surface facing the mixture channel and which has lateral sections adjacent to the channel wall and a middle section running between the lateral sections. The lateral sections have, upstream of the throttle flap, a separation edge for the flow. In the end position, the side of the throttle flap facing the mixture channel defines a reference plane which divides the unit into a first region and a second region. The lateral sections extend, at least directly upstream of the recess, into the second region.

Fuel feed unit and two-stroke engine having a fuel feed unit

A carburetor has a carburetor body wherein an intake channel is formed. A throttle flap is pivotably mounted by a throttle shaft in the carburetor body for controlling the free flow cross-section of the intake channel. The intake channel has a first longitudinal center axis in the region of the throttle shaft. The throttle flap has first and second end positions, wherein the throttle flap opens a larger flow cross-section of the intake channel in the second end position than in the first end position. A partition wall section, on which the throttle flap lies in the second end position, is arranged upstream of the throttle shaft. A choke flap is upstream of the partition wall section and is pivotable between first and second end positions. In their second end positions, the throttle flap and the choke flap overlap in the direction of the first longitudinal center axis.

Carburetor and two-stroke engine with a carburetor

A carburetor has a carburetor housing wherein an intake channel section is arranged. A fuel opening opens into the intake channel section. The carburetor has a fuel pump with a pump membrane delimiting a pump chamber connected to a fuel inlet. A pressure controller has a control membrane separating a control chamber from a compensation chamber. The control chamber is connected to a fuel outlet leading out from the carburetor. The compensation chamber is connected to a compensation connection. The carburetor housing has a carburetor body, a pump cover and an intermediate part arranged therebetween. The fuel inlet, the fuel outlet and the compensation connection are formed on the intermediate part. The fuel inlet, the fuel outlet and the compensation connection are arranged on the side of the carburetor that faces away from the combustion engine.

Carburetor and handheld work apparatus including a combustion engine having said carburetor

A two-stroke engine has a cylinder with a combustion chamber which is bounded by a piston which drives a crankshaft which rotates in a crankcase. The crankcase is connected to the combustion chamber via an overflow passage in the lower dead center region of the piston. The two stroke engine has an intake passage. A carburetor forms a section of the intake passage. The intake passage is partially divided into an air passage, which supplies combustion air into an overflow passage, and a mixture passage which opens into the crankcase. A throttle valve mounted pivotably in the carburetor controls the combustion air quantity supplied to the air and mixture passages. An air-guiding element arranged on the passage wall of the air passage guides the combustion air passing between the throttle valve and passage wall in the idling position of the throttle valve in the direction of the mixture passage.

An internal combustion engine has an intake device having an air filter and at least one port. Combustion air is sucked in from the clean side of the air filter to the internal combustion engine via the port. The intake device has air trunking, in which at least a first section and a second section of the port are guided. The air trunking has a longitudinal center axis, wherein combustion air flows in the first section of the port in a first direction of flow running in the direction of the longitudinal center axis. The combustion air flows in the second section of the port in a second direction of flow oriented in an opposite direction to the first direction of flow and in the direction of the longitudinal center axis. As a result, a compact overall size is achieved with port length.

Internal combustion engine having an intake device

A working apparatus has an internal combustion engine which drives at least one tool via a clutch. The clutch starts the coupling process at an initial engagement speed when the internal combustion engine is accelerated. The internal combustion engine has a piston, an ignition device and an ignition timing control device. The control device provides a first ignition timing for idling and a second ignition timing for full load operation, which is earlier than the first ignition timing. A method for operating the working apparatus provides that the ignition timing is adjusted toward 'late,' with respect to the first ignition timing, when the engine speed drops in a first speed range above the idling speed and below the initial engagement speed.

Working apparatus and a method for operating same

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.

A hand-held power tool has a two-stroke engine with a cylinder with combustion chamber and a piston disposed therein that drives a crankshaft supported in a crankcase. In at least one piston position, crankcase and combustion chamber are connected by a transfer passage. An air passage supplies in at least one piston position combustion air to the transfer passage. A mixture passage for fuel/air mixture is provided. Air and mixture passages in operation are at least partially connected to each other. Part of the mixture passage is formed in a carburetor where a fuel port opens into the mixture passage. The mixture passage opens into the crankcase with a piston-controlled mixture inlet having a width in circumferential direction of the cylinder. Upon upward piston stroke the mixture inlet is connected to the crankcase with a portion of the width before a connection of air passage and transfer passage is established.

Hand-held power tool

A two-stroke engine, comprising: a crankcase; a cylinder connected to said crankcase; a combustion chamber defined by a reciprocally mounted piston within said cylinder; a crankshaft mounted rotatably in said crankcase and drivingly connected with said piston; at least one overflow passage connecting the crankcase and the combustion chamber when the piston is positioned in the lower dead center region; a connecting stub attached to said cylinder which contains an intake passage that opens into the crankcase and supplies fuel and combustion air, said intake passage including therein an air-fuel mixture passage, wherein said connecting stub contains at least one section of the mixture passage; at least one fuel opening for supplying fuel into said mixture passage; and a guiding rib positioned within said connecting stub and oriented longitudinally in the mixture passage and protruding into the mixture passage.

Growing community of inventors

Waiblingen, Germany

Michael Grether