Abstract: A power tool has an internal combustion engine with an injection valve through which fuel is supplied to the internal combustion engine; a crankcase; and a crankshaft arranged in the crankcase so as to be rotatable about an axis of rotation. A fan wheel housing is provided and a fan wheel is arranged in the fan wheel housing and conveys cooling air to the internal combustion engine. In the fan wheel housing a connecting opening is formed. The injection valve is arranged in a cooling area, wherein cooling air is supplied by the fan wheel through the connecting opening to the cooling area.

Abstract: An ignition circuit for a combustion engine has an ignition coil and a control unit for the coil. The coil and the control unit are included in a common component as an ignition module. The module is supplied with voltage by a generator driven by the engine. A spark plug and the coil form a power circuit which includes a line segment to a reference potential outside the module. A sensor detects data of the engine and the output of the sensor is supplied to the module. The sensor is supplied with voltage via a sensor circuit. The sensor circuit and the power circuit use the line segment as a common connection to the reference potential, so that for a defect of the line segment, a missing connection to the reference potential in the high voltage circuit is recognized via the change of the sensor output signals.

Abstract: A handheld work apparatus includes a fuel tank, into which a flexible fuel line projects. A suction head is arranged at the free end of the fuel line. The suction head is connected via the fuel line to a fuel supply device of an internal combustion engine of the work apparatus. The suction head has at least one weight member. The weight member is formed at least partially as a magnet to achieve good cleaning of the fuel without a substantial increase in the weight of the work apparatus.

Abstract: A power tool has an internal combustion engine with a cylinder. An injection valve supplies fuel to the internal combustion engine. A fuel pump conveys fuel from a fuel tank to the injection valve. A fan wheel is provided that is driven by the internal combustion engine. The cylinder is arranged in a first cooling zone of the power tool and the fan wheel conveys cooling air through the first cooling zone. The fuel pump is arranged in a second cooling zone of the power tool. Between the first cooling zone and the second cooling zone a buffer zone is arranged. The buffer zone is separated by at least one first partition from the first cooling zone and by at least one second petition from the second cooling zone.

Abstract: A method for leak-testing a fuel supply system has been provided, wherein the fuel supply system comprises a fuel tank, a fuel injection valve, fuel lines between the fuel tank and the fuel valve, and a control valve controlled by a diaphragm, and wherein the diaphragm bounds a control chamber on one side, the method comprising: acting upon the portion of the fuel supply system upstream of the control valve with a predetermined pressure level, acting upon the side of the diaphragm facing away from the control chamber with a counterforce, wherein the counterforce is equal or greater to the predetermined pressure level. A device for leak-testing a fuel system according to the above method, wherein the device comprises a test pressure unit with at least one test pressure line, wherein said test pressure line is connectable to the fuel supply system.

Abstract: A power tool has a drive motor with an actuating element. The power tool has a power tool housing with a first subassembly and a second subassembly that is connected with the first subassembly. An operating element is supported on the first subassembly. A Bowden cable is disposed within the power tool housing and has a Bowden cable housing and a Bowden cable inner wire arranged in the Bowden cable housing. The actuating element is a part of the second subassembly. The Bowden cable inner wire has a first end connected to the operating element and a second end connected to the actuating element, wherein the operating element acts on the actuating element through the Bowden cable. The Bowden cable housing has a first end and a second end and the first and second ends are secured on the same one of the first and second subassemblies.

Abstract: A hand-guided work apparatus includes a combustion engine to drive a work tool. The combustion engine includes a crankcase (14) in which a crankshaft (16) is rotatably mounted about a rotational axis (44). A pressure sensor (27) and a temperature sensor (26) are arranged on the crankcase (14). The pressure sensor (27) and the temperature sensor (26) are arranged in a common sensor housing (31). In the typical put-down position (8) of the work apparatus, the pressure sensor (27) and the temperature sensor (26) are arranged below a plane (45) which is parallel to the horizontal storage surface (7) and contains the rotational axis (44) of the crankshaft (16). A connecting channel (25) is formed in the sensor housing (31). The connecting channel (25) connects the pressure sensor (27) to the crankcase interior (20) and the base (35) of the connecting channel (25) slopes down toward the crankcase interior (20) in the typical put-down position (8) of the work apparatus.

Abstract: A power tool has an internal combustion engine with a cylinder. An injection valve supplies fuel to the internal combustion engine. A fuel pump conveys fuel from a fuel tank to the injection valve. A fan wheel is provided that is driven by the internal combustion engine. The cylinder is arranged in a first cooling zone of the power tool and the fan wheel conveys cooling air through the first cooling zone. The fuel pump is arranged in a second cooling zone of the power tool. Between the first cooling zone and the second cooling zone a buffer zone is arranged. The buffer zone is separated by at least one first partition from the first cooling zone and by at least one second petition from the second cooling zone.

Abstract: A method for leak-testing a fuel supply system has been provided, wherein the fuel supply system comprises a fuel tank, a fuel injection valve, fuel lines between the fuel tank and the fuel valve, and a control valve controlled by a diaphragm, and wherein the diaphragm bounds a control chamber on one side, the method comprising: acting upon the portion of the fuel supply system upstream of the control valve with a predetermined pressure level, acting upon the side of the diaphragm facing away from the control chamber with a counterforce, wherein the counterforce is equal or greater to the predetermined pressure level. A device for leak-testing a fuel system according to the above method, wherein the device comprises a test pressure unit with at least one test pressure line, wherein said test pressure line is connectable to the fuel supply system.

Abstract: In a method for priming a fuel metering device for an internal combustion engine with a piston arranged in a combustion chamber and driving a crankshaft that is rotatably supported in a crankcase, with a fuel pump that conveys fuel from a fuel tank to a metering valve that opens into a metering chamber at alternating operating pressure, and with a control unit that calculates and controls timing for the metering valve for metering a fuel quantity corresponding to a load situation of the internal combustion engine, the metering valve is kept open, independent of the calculated timing for the metering valve, for a priming duration in a starting phase of the internal combustion engine when the alternating operating pressure of the metering chamber at the mouth of the metering valve is negative and when a fuel system pressure in the fuel metering device is below a target pressure.

Abstract: A hand-guided work apparatus includes a combustion engine to drive a work tool. The combustion engine includes a crankcase (14) in which a crankshaft (16) is rotatably mounted about a rotational axis (44). A pressure sensor (27) and a temperature sensor (26) are arranged on the crankcase (14). The pressure sensor (27) and the temperature sensor (26) are arranged in a common sensor housing (31). In the typical put-down position (8) of the work apparatus, the pressure sensor (27) and the temperature sensor (26) are arranged below a plane (45) which is parallel to the horizontal storage surface (7) and contains the rotational axis (44) of the crankshaft (16). A connecting channel (25) is formed in the sensor housing (31). The connecting channel (25) connects the pressure sensor (27) to the crankcase interior (20) and the base (35) of the connecting channel (25) slopes down toward the crankcase interior (20) in the typical put-down position (8) of the work apparatus.

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: In a method for priming a fuel metering device for an internal combustion engine with a piston arranged in a combustion chamber and driving a crankshaft that is rotatably supported in a crankcase, with a fuel pump that conveys fuel from a fuel tank to a metering valve that opens into a metering chamber at alternating operating pressure, and with a control unit that calculates and controls timing for the metering valve for metering a fuel quantity corresponding to a load situation of the internal combustion engine, the metering valve is kept open, independent of the calculated timing for the metering valve, for a priming duration in a starting phase of the internal combustion engine when the alternating operating pressure of the metering chamber at the mouth of the metering valve is negative and when a fuel system pressure in the fuel metering device is below a target pressure.

Abstract: The absolute crankshaft angle of an internal combustion engine of a hand-held power tool is to be determined. The engine has a cylinder with a combustion chamber delimited by a piston that drives a crankshaft in a crankcase. The crankcase is connected by a transfer passage to the combustion chamber and the transfer port of the transfer passage is piston-controlled. Ignition takes place at an adjusted crankshaft angle. The energy supply unit of the engine is driven by the crankshaft and provides electric energy for ignition. The crankshaft angle is determined in that a signal generator is provided as an energy supply unit and generates an alternating voltage signal caused by a crankshaft revolution. An operating pressure signal of the engine is detected by a pressure sensor. The output signals of the pressure sensor and of the signal generator are linked with one another for determining the absolute crankshaft angle.

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: The absolute crankshaft angle of an internal combustion engine of a hand-held power tool is to be determined. The engine has a cylinder with a combustion chamber delimited by a piston that drives a crankshaft in a crankcase. The crankcase is connected by a transfer passage to the combustion chamber and the transfer port of the transfer passage is piston-controlled. Ignition takes place at an adjusted crankshaft angle. The energy supply unit of the engine is driven by the crankshaft and provides electric energy for ignition. The crankshaft angle is determined in that a signal generator is provided as an energy supply unit and generates an alternating voltage signal caused by a crankshaft revolution. An operating pressure signal of the engine is detected by a pressure sensor. The output signals of the pressure sensor and of the signal generator are linked with one another for determining the absolute crankshaft angle.

Abstract: A carburetor for an internal combustion engine includes an intake channel section (2) as well as a throttle element journalled in the intake channel section (2). The throttle element is adjustable between a full-load position (25) and an idle position (26). A pump (20, 30) is provided for additional fuel metering and this pump includes a pumping chamber (24, 34) and a pump piston (21, 31) guided in the pumping chamber (24, 34). The position of the pump piston (21, 31) is coupled to the position of the throttle element. To ensure an optimal supply of the internal combustion engine with fuel in each operating state, the pump piston (21, 31) is so coupled to the throttle element that fuel is pumped from the pumping chamber (24, 34) into the intake channel section (2) when there is a displacement of the throttle element from the full throttle position (25) into the idle position (26).

Abstract: A carburetor for an internal combustion engine includes an intake channel section (2) as well as a throttle element journalled in the intake channel section (2). The throttle element is adjustable between a full-load position (25) and an idle position (26). A pump (20, 30) is provided for additional fuel metering and this pump includes a pumping chamber (24, 34) and a pump piston (21, 31) guided in the pumping chamber (24, 34). The position of the pump piston (21, 31) is coupled to the position of the throttle element. To ensure an optimal supply of the internal combustion engine with fuel in each operating state, the pump piston (21, 31) is so coupled to the throttle element that fuel is pumped from the pumping chamber (24, 34) into the intake channel section (2) when there is a displacement of the throttle element from the full throttle position (25) into the idle position (26).