Abstract: In a method for operating an internal combustion engine, wherein the internal combustion engine has a cylinder in which a combustion chamber is provided that is delimited by a reciprocating piston guided in the cylinder, wherein the piston is connected by a connecting rod to a crankshaft and wherein the internal combustion engine has a device for supplying fuel and a device for igniting the fuel/air mixture in the combustion chamber at least one engine speed value of the internal combustion engine is determined and evaluated. A pre-ignition state of the internal combustion engine is determined based on the result of the evaluation step.

Abstract: A carburetor (1, 51) has an intake channel (2) wherein a throttle element and a choke element are arranged with the choke element being upstream of the throttle element. The choke element is displaceable between an operating position (8) and at least one starting position (9). A first fuel path is provided which supplies fuel to the intake channel section (2) in dependence upon the underpressure present therein. A first controllable valve (20) for controlling the supplied fuel quantity is mounted in the first fuel path. In order to achieve an adapted fuel supply in different operating states, a second fuel path is provided which defines a bypass line to the first valve (20). A second valve (44, 54) is mounted in the second fuel path. A method for operating the carburetor (1, 51) provides that the second valve (44, 54) is actuated in dependence upon at least one operating parameter of the carburetor (1, 51).

Abstract: In a method for controlling a composition of a fuel/air mixture supplied to an internal combustion engine, which engine has a speed control circuit maintaining an actual rotary speed of the crankshaft within preset limits and a controllable metering device for at least one component of the fuel/air mixture, a disruptive variable is introduced into the valve control circuit at a predeterminable point in time, the activity of an engine speed control circuit is monitored and evaluated immediately after introducing the disruptive variable, and, depending on the evaluation result, at least one parameter having an effect on the operation of the internal combustion engine is adjusted.

Abstract: A carburetor (1, 51) has an intake channel (2) wherein a throttle element and a choke element are arranged with the choke element being upstream of the throttle element. The choke element is displaceable between an operating position (8) and at least one starting position (9). A first fuel path is provided which supplies fuel to the intake channel section (2) in dependence upon the underpressure present therein. A first controllable valve (20) for controlling the supplied fuel quantity is mounted in the first fuel path. In order to achieve an adapted fuel supply in different operating states, a second fuel path is provided which defines a bypass line to the first valve (20). A second valve (44, 54) is mounted in the second fuel path. A method for operating the carburetor (1, 51) provides that the second valve (44, 54) is actuated in dependence upon at least one operating parameter of the carburetor (1, 51).

Abstract: An internal combustion engine having an intake channel that opens into a crankcase. A first fuel channel opens into the intake channel to supply fuel thereto as a function of underpressure in the intake channel. An auxiliary channel opens into a transfer channel that fluidically connects a crankcase to the combustion chamber. A second fuel channel opens into the auxiliary channel and is connected to a storage reservoir for fuel. At least one valve controls the quantity of fuel to be supplied to the engine via the auxiliary channel. Largely fuel-free air is supplied to the engine via the intake channel during idling. During a first revolution of the crankshaft, fuel is supplied via the auxiliary channel, so that a combustible mixture can form in the combustion chamber. During a second revolution, largely fuel-free air is supplied via the auxiliary channel and the combustion chamber is scavenged with largely fuel-free air.

Abstract: A portable handheld work apparatus includes a drive motor configured as an internal combustion engine (1). The work apparatus includes an air filter case (2) arranged in the intake channel of the engine (1). The work apparatus further includes a cover (3) and a locking device (4) for releasably holding the cover (3). An actuating element (6) of the locking device (4) is configured as a slider (7) which is guided so that it is essentially linearly movable.

Abstract: In a method for operating an internal combustion engine, wherein the internal combustion engine has a cylinder in which a combustion chamber is provided that is delimited by a reciprocating piston guided in the cylinder, wherein the piston is connected by a connecting rod to a crankshaft and wherein the internal combustion engine has a device for supplying fuel and a device for igniting the fuel/air mixture in the combustion chamber at least one engine speed value of the internal combustion engine is determined and evaluated. A pre-ignition state of the internal combustion engine is determined based on the result of the evaluation step.

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: In a method for controlling a composition of a fuel/air mixture supplied to an internal combustion engine, which engine has a speed control circuit maintaining an actual rotary speed of the crankshaft within preset limits and a controllable metering device for at least one component of the fuel/air mixture, a disruptive variable is introduced into the valve control circuit at a predeterminable point in time, the activity of an engine speed control circuit is monitored and evaluated immediately after introducing the disruptive variable, and, depending on the evaluation result, at least one parameter having an effect on the operation of the internal combustion engine is adjusted.

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 portable handheld work apparatus such as a motor-driven chain saw (1) includes a housing (2) wherein an internal combustion engine (10) and a carburetor (11) are mounted. A throttle lever (6) is provided which is pivotally journalled on a handle (3). The handle (3) is connected to the housing (2) via at least one antivibration element (33). A vibration gap (9) is configured between the handle (3) and the housing (2). A transmitting unit (13) is provided for transmitting the pivot movement of the throttle lever (6) to the carburetor (11). The transmitting unit includes a rigid transmitting element (17, 37) which bridges the vibration gap (9).

Abstract: An internal combustion engine having an intake channel that opens into a crankcase. A first fuel channel opens into the intake channel to supply fuel thereto as a function of underpressure in the intake channel. An auxiliary channel opens into a transfer channel that fluidically connects a crankcase to the combustion chamber. A second fuel channel opens into the auxiliary channel and is connected to a storage reservoir for fuel. At least one valve controls the quantity of fuel to be supplied to the engine via the auxiliary channel. Largely fuel-free air is supplied to the engine via the intake channel during idling. During a first revolution of the crankshaft, fuel is supplied via the auxiliary channel, so that a combustible mixture can form in the combustion chamber. During a second revolution, largely fuel-free air is supplied via the auxiliary channel and the combustion chamber is scavenged with largely fuel-free air.

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 device that controls the engine speed of an internal combustion engine of a hand-held power tool has a protective control unit. The engine has an ignition control unit for controlling the ignition timing relative to a crank angle of a crankshaft based on the crankshaft speed and also has a centrifugal clutch driven by the crankshaft that begins to engage when a first engine speed is surpassed and is fully engaged when a second engine speed is reached. The protective control unit is activated within an engine speed range between the first and second engine speeds and monitors a dwell time of the actual engine speed within the engine speed range. When a predetermined dwell time of the actual engine speed is surpassed, the protective control unit intervenes in the combustion process and corrects the engine speed to a value that is outside of the engine speed range.

Abstract: A method is for controlling the metering of fuel in a fuel system (30) of an internal combustion engine (1) which is to be started manually. This control is with a currentless open electromagnetic valve (21). The electromagnetic valve (21) is only switched into the closed state when a supply voltage (Uv) is applied and current flows. Within a blocking time (47), which is pregiven by an engine control (13), a supply voltage (Uv) is switched onto the excitation coil of the electromagnetic valve (21) only and the valve (21) is supplied with current only when an underpressure is present in the intake channel (11) of the fuel system (30); whereas, in the remaining time span (50) of the blocking time (47), wherein no underpressure is present, the control unit (20) switches off the supply voltage (Uv) and the valve (21) is in the currentless open state.

Abstract: A method is for controlling the metering of fuel in a fuel system (30) of an internal combustion engine (1) which is to be started manually. This control is with a currentless open electromagnetic valve (21). The electromagnetic valve (21) is only switched into the closed state when a supply voltage (Uv) is applied and current flows. Within a blocking time (47), which is pregiven by an engine control (13), a supply voltage (Uv) is switched onto the excitation coil of the electromagnetic valve (21) only and the valve (21) is supplied with current only when an underpressure is present in the intake channel (11) of the fuel system (30); whereas, in the remaining time span (50) of the blocking time (47), wherein no underpressure is present, the control unit (20) switches off the supply voltage (Uv) and the valve (21) is in the currentless open state.

Abstract: An electromagnetic valve (1, 21) includes a coil (2) which is fixedly connected to an iron core (3). An armature plate (5) is movably journalled in the direction of the coil longitudinal axis (22) relative to the iron core (3). At least two flow channels (8, 9; 26, 27, 28, 29) open at the armature plate (5) and are fluidly separated from each other when a current flows in the coil (2). A small structural size with a simple manufacture of the electromagnetic valve (1, 21) is achieved in that a flow channel (8; 26, 27, 28) opens in the peripheral region (32) of the armature plate (5) at the end (33) of the armature plate (5) facing toward the coil (2).

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 portable handheld work apparatus includes a drive motor configured as an internal combustion engine (1). The work apparatus includes an air filter case (2) arranged in the intake channel of the engine (1). The work apparatus further includes a cover (3) and a locking device (4) for releasably holding the cover (3). An actuating element (6) of the locking device (4) is configured as a slider (7) which is guided so that it is essentially linearly movable.

Abstract: A device that controls the engine speed of an internal combustion engine of a hand-held power tool has a protective control unit. The engine has an ignition control unit for controlling the ignition timing relative to a crank angle of a crankshaft based on the crankshaft speed and also has a centrifugal clutch driven by the crankshaft that begins to engage when a first engine speed is surpassed and is fully engaged when a second engine speed is reached. The protective control unit is activated within an engine speed range between the first and second engine speeds and monitors a dwell time of the actual engine speed within the engine speed range. When a predetermined dwell time of the actual engine speed is surpassed, the protective control unit intervenes in the combustion process and corrects the engine speed to a value that is outside of the engine speed range.