Abstract: A two-cycle engine includes a reciprocating piston reciprocable in a combustion chamber and interconnected with a crankshaft in a crankcase. A transfer channel selectively fluidly connects the crankcase with the combustion chamber so a fuel/air mixture in the crankcase enters the combustion chamber for discharging exhaust gas from the combustion chamber. The transfer channel has a constructive volume between an inlet window into the combustion chamber and an opening window into the crankcase such that the volume of essentially fuel-free air that is drawn into the transfer channel during an intake stroke is no more than 75% of the constructive volume of the transfer channel.

Abstract: 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.

Abstract: An intake arrangement for an internal combustion engine includes an intake channel (80) which connects the clean side (81) of an air filter (41) to the engine. The intake channel (80) is subdivided by a partition wall (11) into an air channel (8) and a mixture channel (21). A throttle flap is mounted in the intake channel (80). A fuel opening (27, 28) for supplying fuel opens into the mixture channel (21). In order to avoid a throw back of fuel from the mixture channel (21) into the air channel (8), it is provided that the clean side (81) of the air filter (41) is divided into two chambers (82 and 83) and the mixture channel (21) opens into the first chamber (82) and the air channel (8) opens into the second chamber (83).

Abstract: A two-stroke engine (1) for a work apparatus includes a combustion chamber (3) configured in a cylinder (2). The engine includes a piston (5, 21) which drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) includes at least three transfer channels (10, 11, 20) which connect the combustion chamber (3) to the crankcase (4) at pregiven control times. At pregiven control times, fuel is injected in the region of a transfer channel (10, 11, 20). A first component quantity of the fuel is transfer synchronously injected into the channel and a second component quantity from a preceding injecting cycle exits from the crankcase (4) into the combustion chamber (3). For this purpose, an injection nozzle (19) is mounted in at least one transfer channel (10). The injection nozzle (19) injects fuel into the transfer channel (10) open to the cylinder (2).

Abstract: A two-stroke engine having a combustion chamber (3) configured in a cylinder (2) is disclosed. The combustion chamber is delimited by a reciprocating piston (5). The two-stroke engine includes at least one transfer channel (10, 11) configured in the cylinder and fluidly connecting the combustion chamber and a crankcase (4). The transfer channel is delimited by a set wall (19) with respect to the interior space (18) of the cylinder at least over a portion of its longitudinal extent. The set wall may be held with respect to the interior space of the cylinder by a device configured with the cylinder as one part. A method for manufacturing the two-stroke engine provides that the cylinder is produced in the pressure-cast die process and a set wall is pushed into the cylinder between the cylinder interior space and the transfer channels and is thereafter fixed via a holding element.

Abstract: An intake system for the combustion air of a motor of a hand held implement is provided. The system includes an air filter and a centrifugal separator. The air filter has a dirt chamber and a clean chamber that is separated therefrom by a filter medium. The clean chamber is fluidically connected with a carburetor of the motor to convey combustion air to the motor. The centrifugal separator splits the air stream into a core flow having low particle density and a peripheral flow having high particle density. The centrifugal separator includes at least two cyclones, wherein the discharged flows from the cyclones are respectively combined in pairs and open out into a common suction tube.

Abstract: A portable handheld lawn edger includes a cutterhead (2) at the end (16) of a guide tube (4) as well as an internal combustion engine (3) at the other end (17). The engine is connected to the cutter blade (5) via a drive shaft (20) in the guide tube (4) and in the cutterhead (2). The cutter blade is mounted for rotation about an axis (6), which lies parallel to the ground during cutting operation, and is guided along the edge. A guide wheel (27) is provided on the end of the cutterhead (2) facing toward the engine (3). The cutterhead (2) can be rolled over the ground with the aid of the guide wheel (27). The service life of the edge cutter (1) is increased and the manufacturing costs are reduced in that the cutterhead (2) is provided with a spacer (7, 9) approximately at the elevation of the drive axis (6) of the cutter blade (5). The spacer (7, 9) projects from the cutterhead and is set on the ground and prevents abrasion of the cutterhead (2).

Abstract: A two-stroke engine (1), especially for a portable handheld work apparatus, includes a combustion chamber (3) configured in a cylinder (2). The combustion chamber (3) is delimited by a piston (5) which moves upwardly and downwardly. Combustion air is supplied to the engine (1) via an air channel (19). The air channel (19) opens with an air channel window (27) into the cylinder (2). The crankcase (4) of the two-stroke engine (1) is connected at pregiven piston positions to the combustion chamber (3) via transfer channels (10, 11, 15, 23, 32, 34). The transfer channels (10, 11, 15, 23, 32, 34) open with inlet windows (12, 13, 17, 24, 33, 35) into the cylinder (2). An injection nozzle (16) opens into at least one transfer channel (15, 23, 34). In the region of top dead center of the piston (5, 25), the air channel is connected via a piston window (18, 26) to a transfer channel (15, 23, 34).

Abstract: A two-stroke engine, especially for a portable handheld work apparatus, has a combustion chamber (3) configured in a cylinder (2). The combustion chamber is delimited by a reciprocating piston (5). The two-stroke engine (1) includes at least one transfer channel (10, 11) which is configured in the cylinder (2) and this transfer channel fluidly connects the combustion chamber (3) and a crankcase (4) at pregiven positions of the piston. The transfer channel (10, 11) is delimited by a set wall (19) with respect to the interior space (18) of the cylinder at least over a portion of its longitudinal extent. In order to provide for a simple manufacture of the two-stroke engine (1), the set wall (19) is held with respect to the interior space (18) of the cylinder by a device configured with the cylinder (2) as one part.

Abstract: A two-cycle engine is provided, especially for a portable, manually-guided implement, and has a cylinder in which is formed a combustion chamber that is delimited by a reciprocating piston that, via a connecting rod, drives a crankshaft mounted in a crankcase. The engine has an inlet and an outlet. In prescribed positions of the piston, the crankcase is fluidically connected with the combustion chamber via at least one transfer channel. The engine has an air channel that conveys essentially fuel-free air and that, in a port-controlled manner, is fluidically connected with at least one transfer channel: To achieve low exhaust gas values, the quantity of air that, at a rated speed, flows from the air channel into the transfer channel during a piston stroke has a volume that is at least 75% of the volume of the transfer channel between the inlet window, via which the transfer channel opens into the combustion chamber, and the opening window, via which the transfer channel opens into the crankcase.

Abstract: A two-stroke engine (1) for a work apparatus includes a combustion chamber (3) configured in a cylinder (2). The engine includes a piston (5, 21) which drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) includes at least three transfer channels (10, 11, 20) which connect the combustion chamber (3) to the crankcase (4) at pregiven control times. At pregiven control times, fuel is injected in the region of a transfer channel (10, 11, 20). A first component quantity of the fuel is transfer synchronously injected into the channel and a second component quantity from a preceding injecting cycle exits from the crankcase (4) into the combustion chamber (3). For this purpose, an injection nozzle (19) is mounted in at least one transfer channel (10). The injection nozzle (19) injects fuel into the transfer channel (10) open to the cylinder (2).

Abstract: The invention is directed to a method for operating a two-stroke engine in a portable handheld work apparatus. The engine includes a cylinder (12) and a combustion chamber (26) which is delimited by a reciprocating piston (14). The combustion chamber includes an outlet (28) discharging exhaust gases and an inlet (30) of a storage channel (34). The inlet (30) lies approximately opposite the outlet (28) and the other end of storage channel (34) opens via a controlled end (38) into the crankcase (18). Between its ends, the storage channel (34) is connected to a first fuel metering device (20) of a first fuel path; whereas, the crankcase (18) has a crankcase inlet (24) which is connected to a second fuel metering device (19) 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 (22).

Abstract: A two-stroke engine having charge stratification for portable, manually guided implements is provided. Formed in a cylinder is a combustion chamber that is delimited by a reciprocating piston that by means of a connecting rod drives a crankshaft in a crankcase. The combustion chamber has an exhaust port for exhaust gases and an intake port for rich mixture. The intake port forms one end of a feed channel, the other end of which opens into the crankcase. Between its ends, the feed channel is connected with a mixture-forming device. The crankcase has an air inlet for pure combustion air, which passes via a transfer channel from the crankcase into the combustion chamber. The intake port of the feed channel into the combustion chamber is, in the stroke direction of the piston, provided above the air inlet into the crankcase. At least a portion of the feed channel is embodied as an external component of the engine.

Abstract: An internal combustion engine, for example a two-stroke engine having scavenging collection, is provided. The combustion chamber formed in the cylinder is delimited by a reciprocating piston. A fuel/air mixture prepared in the Venturi section of a diaphragm carburetor is supplied to the engine. The air portion of the mixture is conveyed to the Venturi section via an intake channel, and the fuel portion is conveyed to the Venturi section via a main nozzle path that branches off from a fuel-filled control chamber to which fuel is supplied via a fuel line and a feed valve that is controlled by a control diaphragm that delimits the control chamber. A device is provided for varying the air portion and/or the fuel portion at full load. Connected to the device is a control unit that receives, as an input variable, an operating parameter of the engine that varies as a function of engine speed. The device is actuated as a function of the output signal of the control unit.

Abstract: The invention relates to an internal combustion engine and especially to a drive motor in a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine or the like. The engine is formed from a cylinder (7) with a combustion chamber (34) which is delimited by the reciprocating piston (35). The piston (35) drives a crankshaft (38) which is rotatably journalled in a crankshaft housing (37) via a connecting rod (36). In the combustion chamber (34) an outlet (29) is provided through which the oxygen-rich exhaust gases (16) and oxygen-poor exhaust gases (18) flow out. Transfer channels (40) are configured in the cylinder (7) for supplying an air/fuel mixture prepared by a mixture preparation device (39) and gas-feeding channels (41) are configured for supplying fuel-poor, oxygen-rich gases in the combustion chamber (34). An exhaust-gas muffler (2) is assigned to the outlet (29) according to the invention to obtain an exhaust-gas quality which remains the same.

Abstract: A two-cycle engine having forward scavenging is provided, as used in manually-guided implements. The mixture is drawn into the crankcase via a butterfly valve carburettor and is conveyed into a combustion chamber via transfer channels formed in the cylinder. An air duct is connected via a controllable connection with a transfer channel in order during a load state of the engine to supply essentially fuel-free air to the transfer channel. In order during idling and partial load to convey a fuel quantity adapted to the drawn-in air, yet during full throttle to achieve a separated supply of air and mixture, a dividing wall that extends in the direction of flow of air is provided in the intake duct of the carburettor. In the pivot region of the butterfly valve, a connecting aperture is provided in the dividing wall and is closed in full throttle by a completely open butterfly valve.

Abstract: The invention relates to a two-cycle engine for a drive engine in a portable, manually operated tool. The combustion chamber formed in a cylinder is delimited by a piston that moves up and down, whereby the piston, by means of a connecting rod, drives a crankshaft rotatably mounted in a crankcase. The combustion chamber has an outlet for removing waste gases, and provided for supplying a fuel/air mixture prepared by a mixture preparation device, and combustion air, are gas-supplying channels that open into the combustion chamber. In order to reduce scavenging losses, it is provided that for the entire duration of the gas exchange exclusively air flows in the area near the outlet and exclusively fuel/air mixture flows out of the crankcase in the area further away from the outlet.

Abstract: The invention relates to a two-stroke engine for a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine, brushcutter or the like. A crankcase (4) is formed below the engine cylinder (2). A piston (5) moves up and down in the cylinder (2) and drives a crankshaft (7) rotatably journalled in the crankcase (4). A fuel-containing mixture is supplied via a membrane carburetor (8) to the combustion chamber (3) delimited between the piston (5) and the cylinder (2). A bypass channel (22) is provided parallel thereto and supplies essentially fuel-free air to the combustion chamber (3). The bypass channel (22) opens into a channel segment (21) via a connecting piece (24) fixedly attached to the cylinder (2). The channel segment (21) is formed in the cylinder wall (16). A spark plug (20) and an ignition control device (34) are assigned to the combustion chamber (3).

Abstract: A cylinder is produced of die cast metal and is for a two-stroke engine in a portable handheld work apparatus such as a motor chain saw. A combustion chamber (3) is formed in the cylinder (2) and this combustion chamber is delimited by a piston (5). In the cylinder wall (16), there is an outlet (10) for conducting away the combustion gases from the combustion chamber (3). Transfer channels (14a, 14b) are provided which open into the combustion chamber (3) via transfer windows (12, 15) and supply the operating medium from the crankcase (4) needed for operating the two-stroke engine. The transfer channels (14a, 14b) are configured in the cylinder wall (16) as channels opening radially to the outside and are closed by a seated cover (23).

Abstract: The invention relates to a two-stroke engine in a portable handheld work apparatus such as a motor chain saw. A combustion chamber (3) is formed in a cylinder (2) and is delimited by a piston (5). The piston (5) drives a crankshaft (7) via a connecting rod (6). The crankshaft is journalled in a crankcase (4). Air is supplied to the combustion chamber (3) via a first outlet-near transfer channel (15); whereas, the air/fuel mixture, which is needed for operation, flows in via a second outlet-remote transfer channel (12) from the crankcase (4). The constructive volume of the outlet-near transfer channel (15) is designed to be approximately 20% to 60% of the volumetric total air input of the engine (1) in order to achieve a complete charge of the combustion chamber while having low scavenging losses.