Abstract: A two-stroke engine has a cylinder with a combustion chamber and a reciprocating piston for driving a crankshaft. Transfer passages connect the crankcase in at least one position of the piston with the combustion chamber and open by piston-controlled transfer ports into the combustion chamber. An inlet opens into the crankcase and an outlet is provided at the combustion chamber. The engine is dividable into four sectors parallel to a longitudinal cylinder axis. The transfer port of a first transfer passage is arranged in the first sector, the outlet is arranged in the second sector, the transfer port of a second transfer passage is provided in the third sector, and the inlet is arranged in the fourth sector. Within the cylinder the first and second transfer passages, at a spacing from a separation plane between cylinder and crankcase, pass together into one of the second and fourth sectors.

Abstract: A cover arrangement of a hand-held power tool has a cover having at least one fastening element for connecting the cover to an additional component of the power tool. The cover has a wall component having a shape-elastic yielding support forming a monolithic part of the cover. The at least one fastening element is arranged on the support.

Abstract: A two-stroke engine has a cylinder with a combustion chamber and a reciprocating piston for driving a crankshaft. Transfer passages connect the crankcase in at least one position of the piston with the combustion chamber and open by piston-controlled transfer ports into the combustion chamber. An inlet opens into the crankcase and an outlet is provided at the combustion chamber. The engine is dividable into four sectors parallel to a longitudinal cylinder axis. The transfer port of a first transfer passage is arranged in the first sector, the outlet is arranged in the second sector, the transfer port of a second transfer passage is provided in the third sector, and the inlet is arranged in the fourth sector. Within the cylinder the first and second transfer passages, at a spacing from a separation plane between cylinder and crankcase, pass together into one of the second and fourth sectors.

Abstract: An ignition circuit is for an internal combustion engine in a handheld portable work apparatus. A combustion chamber (4) is configured in the cylinder (3) of the engine (1) which is delimited by a piston (5) driving a crankshaft (7). A pole wheel (10) revolves with the crankshaft (7) and is assigned to an induction loop (13). The pole wheel periodically changes the magnetic flux in the induction loop. An ignition capacitor (16) is charged by a charge coil (14) of the induction loop and is discharged via a discharge circuit (15) via an ignition coil (17). The ignition coil is connected to a spark plug (19) projecting into the combustion chamber. For achieving a powerful ignition spark, the discharge of the ignition capacitor is prevented by an rpm evaluation circuit (23) when the rpm curve (30) exhibits an rpm change (?n) which exceeds a pregiven threshold value.

Abstract: A vessel (1) of a portable handheld work apparatus is provided for liquid operating substances such as fuel, oil or the like. The vessel (1) has a vessel wall (2) of injection-molded plastic and a viewing window (3) integrated into the vessel wall (2). The viewing window is provided for viewing the fill level. The vessel wall (2) and the viewing window (3) are configured as a two-component injection-molded part. Mutually adjoining edges (4, 5) of the vessel wall (2) and the viewing window (3) have a tongue-and-groove connection (6) with at least one groove (7) and at least one tongue (8).

Abstract: 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.

Abstract: A method for making a plastic molded part (12) includes injecting plastic (13) into a foil part (2) with plastic (13) being injected into an injection mold (7) at the rear side of the foil part. The plastic molded part (12) is especially a housing component of a portable handheld work apparatus. The method includes providing a plurality of foil parts (2) in a foil strip (1). Thereafter, the foil strip (1) is positioned in the work region of the injection mold (7). A foil part (2) is taken out of the foil strip (1) utilizing a grabber (6) and is placed in the injection mold (7). Thereafter, the foil part (2), which is placed in the injection mold (7), is back injected with the plastic (13).

Abstract: A piston (5) for a two-stroke engine (1) has a piston base (19) and at least one piston pin boss (24). The piston pin boss (24) has a bore for accommodating a piston pin. At the piston pin boss (24), two mutually opposite-lying planar clamping surfaces (36, 37) are formed. The piston (5) is produced in a pressure die cast process and is thereafter clamped at the clamping surfaces (36, 37) and a stop surface (35). In this clamping state, all machining operations of the piston (5) can be carried out so that a high dimensional stability of the piston (5) results.

Abstract: A two-stroke engine is for a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine, brushcutter or the like. A combustion chamber (3) is configured in the cylinder (2) of the engine (1) and is delimited by a reciprocating piston (5). The piston (5) drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in the crankcase (4). The two-stroke engine includes a discharge opening (10) for conducting exhaust gases out of the combustion chamber (3) and an inlet (11) via which an air/fuel mixture is conducted to the crankcase (4). The air/fuel mixture passes via at least one transfer channel (12, 15) from the crankcase (4) into the combustion chamber (3). The transfer channels (12, 15) open at one end with a transfer window (13, 16) into the combustion chamber (3) and are connected at the other end to the crankcase (4). A bypass channel (20) conducts essentially fuel-free gas and opens via a membrane valve (19) into the transfer channel (15).

Abstract: A cover arrangement of a hand-held power tool has a cover having at least one fastening element for connecting the cover to an additional component of the power tool. The cover has a wall component having a shape-elastic yielding support forming a monolithic part of the cover. The at least one fastening element is arranged on the support.

Abstract: An ignition circuit is for an internal combustion engine in a handheld portable work apparatus. A combustion chamber (4) is configured in the cylinder (3) of the engine (1) which is delimited by a piston (5) driving a crankshaft (7). An electromagnetic induction loop (13) and a pole wheel (10) are provided. The pole wheel (10) revolves with the crankshaft (7) and is assigned to the induction loop (13). The pole wheel (10) periodically changes the magnetic flux in the induction loop (13). An ignition capacitor (16) is charged by a charge coil (14) of the induction loop (13) and is discharged via a discharge circuit (15) via an ignition coil (17). The ignition coil (17) is connected to a spark plug (19) projecting into the combustion chamber (4). For achieving a powerful ignition spark, the discharge of the ignition capacitor (16) is prevented by an rpm evaluation circuit (23) when the rpm curve (30) exhibits an rpm change (?n) which exceeds a pregiven threshold value.

Abstract: The invention relates to a portable handheld work apparatus including a chain saw, a vacuum/blower apparatus or the like. The work apparatus has a handle (2) for carrying and guiding the work apparatus (1). Thumb supports (4, 5) are provided on both sides with respect to the longitudinal axis (3) of the handle (2).

Abstract: A two-cycle engine in a portable, manually-guided implement, such as a power chain saw, a cut-off machine, a brush cutter, or the like, is provided. The cylinder has a combustion chamber that is delimited by a reciprocating piston that via a connecting rod drives a crankshaft that is mounted in a crankcase so as to be rotatable about a crankshaft axis. The cylinder has an outlet for conveying exhaust gases out of the combustion chamber, with the outlet having an axis of the channel thereof. The cylinder also has an inlet for supplying a fuel/air mixture to the crankcase. By means of at least two transfer channels, the fuel/air mixture is conveyed out of the crankcase and into the combustion chamber, with the transfer channels being disposed symmetrically relative to the axis of the channel of the outlet.

Abstract: A two-stroke engine is for a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine, brushcutter or the like. A combustion chamber (3) is configured in the cylinder (2) of the engine (1) and is delimited by a reciprocating piston (5). The piston (5) drives a crankshaft (7) via a connecting rod (6). The crankshaft (7) is rotatably journalled in the crankcase (4). The two-stroke engine includes a discharge opening (10) for conducting exhaust gases out of the combustion chamber (3) and an inlet (11) via which an air/fuel mixture is conducted to the crankcase (4). The air/fuel mixture passes via at least one transfer channel (12, 15) from the crankcase (4) into the combustion chamber (3). The transfer channels (12, 15) open at one end with a transfer window (13, 16) into the combustion chamber (3) and are connected at the other end to the crankcase (4). A bypass channel (20) conducts essentially fuel-free gas and opens via a membrane valve (19) into the transfer channel (15).

Abstract: 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.

Abstract: A two-cycle engine is provided that has a cylinder in which is formed a combustion chamber delimited by a reciprocating piston that via a connecting rod drives a crankshaft rotatably mounted in a crankcase. An inlet is provided for a supply of fuel into the crankcase, and an outlet leads out of the combustion chamber. In predetermined positions of the piston the crankcase communicates with the combustion chamber via at least one transfer channel. The cover is secured to a connecting flange of the cylinder, the cover closes off the transfer channel on an outer side of a cylinder, the connecting flange is inclined relative to the longitudinal axis of the cylinder by an angle that opens in a direction toward the crankcase.

Abstract: A muffler assembly for an internal combustion engine of a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine or the like includes an exhaust-gas muffler (1) which has a muffler housing (10). The muffler housing (10) is formed essentially from two half shells (24, 25) connected substantially fluid-tight to each other. The interior space of the muffler housing (10) includes at least two chambers (2, 3) which are partitioned from each other by a partition wall (4). A catalytic converter (5) is mounted in the partition wall (4). In the interior space of the muffler housing (10), an exhaust-gas inlet (6) opens which is connected to an exhaust-gas stub (9) of the cylinder (8) of the engine. The exhaust-gas muffler has an exhaust-gas outlet (7) which conducts exhaust gas from the interior space.

Abstract: A two-cycle engine, especially for a portable, manually-guided implement, is provided. The engine has a cylinder with a combustion chamber delimited by a reciprocating piston. An inlet opens into the cylinder for supplying fuel/air mixture into a crankcase. The engine has an outlet for exhaust gases from the combustion chamber and at least one transfer channel, which, in prescribed positions of the piston, fluidically connects the crankcase with the combustion chamber. The engine has a clean air path that includes an air channel, a piston window and a transfer channel. In prescribed positions of the piston the air channel is fluidically connected via the piston window with an inlet window of the transfer channel. The direction of flow in the clean air path from inlet to outlet extends uniformly, in at least one piston position, and in a plane that extends perpendicular to the longitudinal axis of the cylinder.

Abstract: The invention relates to a method for operating a two-stroke engine having scavenging-advance storage. The combustion chamber (3) which in configured in the cylinder (2) is supplied with an air/fuel mixture via a transfer channel (12, 15). This air/fuel mixture is drawn by induction through an inlet into the crankcase (4) during the intake phase. During the intake phase, a fuel-free fluid such as pure air is inducted via a fluid channel (17) and stored in the transfer channel. To obtain good exhaust-gas values while also having reduced fuel consumption and reliable lubrication, lambda (?) of the air/fuel mixture, which is stored in the crankcase (4), is adjusted in a range of approximately 0.2 to 0.6 in the part-load and full-load ranges of the two-stroke engine (1).

Abstract: A muffler arrangement includes an exhaust-gas muffler, which is subdivided into an inlet space and an outlet space. An exhaust-gas stub of an internal combustion engine opens into the inlet space. Exhaust gas is conducted from the outlet space into an air channel via an exhaust-gas outlet. The air channel is formed between the housing of the exhaust-gas muffler and an outer cover and extends along a side of the exhaust-gas muffler. A cooling-air component flow is branched from a cooling-air flow of a cooling-air blower and enters at a first end of the air channel. The cooling-air component flow exits again at the second end of the air channel.