Abstract: A method for operating an internal combustion engine having a fuel system which feeds fuel at a given pressure to a metering valve provides that a controller defines the opening time and the closing time of the metering valve and correspondingly actuates the metering valve so that the metering valve opens and closes at the defined times. In order to permit precise metering of fuel even in high-speed internal combustion engines there is provision for the controller to define at least one of the times for the opening or closing of the metering valve while taking into account the counterpressure actually prevailing at the outlet opening of the metering valve.

Abstract: A drive arrangement for a hand-guided working machine for agriculture, forestry and horticulture applications. The drive arrangement comprises an electric motor, a DC power source for electrical energy, and a control apparatus for the electric motor which is fed from the DC power source. The electric motor has a specific, in particular linear, characteristic curve between the electric current which is consumed by the electric motor and the rotational speed of an output shaft of the electric motor. The control apparatus has current-limiter which limits the current which flows through the electric motor to a maximum value in order to protect the electric motor against overloading. The control apparatus limits the current consumption of the electric motor in a range of low rotational speeds to values which are considerably smaller than the characteristic curve values which are given for these rotational speeds by the characteristic curve of the electric motor, as a function of the rotational speed.

Abstract: A portable handheld work apparatus has a drive motor as well as an adjusting element for controlling the drive motor. The work apparatus has at least one actuating element. A movement of the actuating element is transmitted to the adjusting element via a transmitting unit. A good operator control is achieved when at least one transmitting characteristic (49, 50; 89, 90; 309, 310) of the transmitting unit runs nonlinearly as a function of the actuating displacement (s) of the actuating element.

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: 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 hedge trimmer has a housing. A blade bar projects forwards from the housing along a longitudinal axis. An electric drive motor drives the blade bar. At least one battery supplies the drive motor with electrical energy. The blade bar, the drive motor and the battery are mounted on the housing. The hedge trimmer has a top handle arranged above a center of gravity of the hedge trimmer, and a rear handle arranged behind the hedge-trimmer center of gravity. The battery is arranged on the housing at least mainly in front of the rear handle.

Abstract: A portable spray apparatus (1) is provided to selectively discharge liquid spray medium and solid dust medium with a blower airflow (7) generated by a blower (6). An adaptor (8) is provided which has at least a channel section (9) of a liquids channel (10) for the liquid spray medium and a channel section (11) of a solids channel (12) for the solid dust medium. The adaptor (8) is releasably connected to a supply vessel (4). The liquids channel (10) and the solids channel (12) open into the blower airflow (7). Various built-in positions of the supply vessel (4) and of the adaptor (8) are freely selectable relative to each other and to the blower unit (3) by the operator. In one built-in position, the liquids channel (10) is connected via its channel section (9) to an interior space (13) of the supply vessel (4) and, in another built-in position, the solids channel (12) is connected to this interior space (13) via the channel section (11) thereof.

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 power tool has an internal combustion engine having a crankcase and a reciprocating piston. The interior of the crankcase is delimited by the reciprocating piston. A pump for conveying a fluid is provided, wherein the pump is driven by a fluctuating pressure in the crankcase. The pump conveys a foreign fluid that is different from an operating medium of the internal combustion engine. The power tool is a spraying device and the pump conveys a medium to be sprayed.

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: A cylinder housing (1) is cast with a cylinder wall (2) in the making of a cylinder for an internal combustion engine. The cylinder wall delimits an interior space (3) for accommodating a reciprocating piston and, thereafter, a control window (5) is machined into the cylinder wall (2) as an opening of a transfer channel (4) into the interior space (3). A two-stage machining for forming the control window (5) is provided in order to make possible a rapid and cost effective manufacture of the cylinder. In a first step with a work tool (7) having a rotating primary movement (11), a breakthrough (10) is machined into the cylinder wall (2) and, in a second step with a work tool, the breakthrough (10) is widened to the wanted dimensions of the control window (5).

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 two-cycle engine 1 is provided and has a cylinder in which is formed a combustion chamber that is delimited by a piston which, via a connecting rod, drives a crankshaft rotatably mounted in a crankcase. The engine has an air duct that communicates with a transfer channel, and a mixture channel via which fuel/air mixture is drawn into the crankcase. At least a portion of the length of the mixture channel is separated from the air duct by a dividing wall that extends in a direction of flow of the air. The dividing wall separates the channels from one another in such a way that the ratio of the cross-sectional area of the mixture channel to the cross-sectional area of the air duct is approximately in the range of 0.5 to 1.9.

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: 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: 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 cylinder housing (1) is cast with a cylinder wall (2) in the making of a cylinder for an internal combustion engine. The cylinder wall delimits an interior space (3) for accommodating a reciprocating piston and, thereafter, a control window (5) is machined into the cylinder wall (2) as an opening of a transfer channel (4) into the interior space (3). A two-stage machining for forming the control window (5) is provided in order to make possible a rapid and cost effective manufacture of the cylinder. In a first step with a work tool (7) having a rotating primary movement (11), a breakthrough (10) is machined into the cylinder wall (2) and, in a second step with a work tool, the breakthrough (10) is widened to the wanted dimensions of the control window (5).

Abstract: A two-cycle engine 1 is provided and has a cylinder in which is formed a combustion chamber that is delimited by a piston which, via a connecting rod, drives a crankshaft rotatably mounted in a crankcase. The engine has an air duct that communicates with a transfer channel, and a mixture channel via which fuel/air mixture is drawn into the crankcase. At least a portion of the length of the mixture channel is separated from the air duct by a dividing wall that extends in a direction of flow of the air. The dividing wall separates the channels from one another in such a way that the ratio of the cross-sectional area of the mixture channel to the cross-sectional area of the air duct is approximately in the range of 0.5 to 1.9.

Abstract: A two-stroke engine, especially for a portable handheld work apparatus, includes a combustion chamber configured in a cylinder. The combustion chamber is delimited by a piston which moves upwardly and downwardly. Combustion air is supplied to the engine via an air channel. The air channel opens with an air channel window into the cylinder. The crankcase of the two-stroke engine is connected at pregiven piston positions to the combustion chamber via transfer channels. The transfer channels open with inlet windows into the cylinder. An injection nozzle opens into at least one transfer channel. In the region of top dead center of the piston, the air channel is connected via a piston window to a transfer channel. An injection nozzle is arranged in the transfer channel and injects fuel into the transfer channel during the induction of combustion air into the crankcase.

Abstract: A two-cycle engine having forward scavenging is provided. Mixture drawn into the crankcase via a butterfly valve carburetor is conveyed into a combustion chamber via transfer channels in the cylinder. An air duct is connected via a controllable connection with a transfer channel to supply essentially fuel-free air thereto during a load state of the engine. To convey a fuel quantity adapted to drawn-in air during idling and partial load, yet during full throttle to achieve separated supply of air and mixture, a dividing wall extends in the direction of flow of air in the carburetor intake duct. In the pivot region of the butterfly valve, a connecting aperture in the dividing wall is closed in full throttle by a completely open butterfly valve. During idling and partial load the connecting aperture is open so that a uniform pressure can form in the intake duct in conformity with drawn-in air.