Abstract: An intake system for preparing combustion air (1) is for an internal combustion engine of a portable handheld work apparatus. The intake system includes: a carburetor (2); an air filter (3) which is connected upstream of the carburetor (2); and, a filter case (4) which closes the air filter (3) from the outside. A combustion air channel (5) leads from a take-up opening (6) in a cooling air fan (7) of the engine to an inlet opening (24) in the filter case (4). The filter case (4) includes at least one defined ventilation opening (8) for connecting an inner space (9) of the filter case (4) to the ambient air. The flow cross section of the ventilation opening (8) is so designed that the airflows through the inlet opening (24), the intake opening (18) of the carburetor (2) and the ventilation opening (8) are compensated at the rated rpm of the engine and that a uniform pressure level adjusts in the inner space (9) of the filter case (4).

Abstract: A manually guided implement having an internal combustion engine and a carburetor for supplying a fuel/air mixture to the engine is provided. Disposed between the internal combustion engine and the carburetor is a housing wall in which is arranged a preheating window for guiding to the carburetor a preheating air stream that is heated-up by the internal combustion engine. A pivotably mounted switching element is provided for closing and opening the preheating window.

Abstract: An intake system for preparing combustion air (1) is for an internal combustion engine of a portable handheld work apparatus. The intake system includes: a carburetor (2); an air filter (3), which is connected upstream of the carburetor (2); and, a filter case (4) which closes the air filter (3) from the outside. A combustion air channel (5) leads from a take-up opening (6) in a cooling air fan (7) of the engine to an inlet opening (24) in the filter case (4). The filter case (4) includes at least one defined ventilation opening (8) for connecting an inner space (9) of the filter case (4) to the ambient air. The flow cross section of the ventilation opening (8) is so designed that the air flows through the inlet opening (24), the intake opening (18) of the carburetor (2) and the ventilation opening (8) are compensated at the rated rpm of the engine and that a uniform pressure level adjusts in the inner space (9) of the filter case (4).

Abstract: A manually guided implement having an internal combustion engine and a carburetor for supplying the engine with a fuel/air mixture is provided. A combustion air stream is drawn in through the carburetor by the engine. A warming medium heated up by the engine can be passed along the outer surfaces of the carburetor separate from the combustion air stream.

Abstract: A manually guided implement having an internal combustion engine and a carburetor for supplying a fuel/air mixture to the engine is provided. Disposed between the internal combustion engine and the carburetor is a housing wall in which is arranged a preheating window for guiding to the carburetor a preheating air stream that is heated-up by the internal combustion engine. A pivotably mounted switching element is provided for closing and opening the preheating window.

Abstract: A suction head is provided for the end of a fuel hose in a fuel tank of a portable implement. The suction head comprises a cup-shaped housing of polymeric material that is closed off by a cap. Provided on the cap is a connector for the end of the fuel hose. The outer surface of the housing is provided with window-like cutouts that are covered by a filter mesh. In order also with narrow, fragmented tank housings to ensure an immersion of the suction head into the fuel in every operating position, a rod-shaped weight member is disposed in the center of the housing. This weight member extends from the base of the housing to the cap, with a first end of the weight member being held on the base and a second end being held on the cap.

Abstract: A manually guided implement having an internal combustion engine and a carburetor for supplying the engine with a fuel/air mixture is provided. A combustion air stream is drawn in through the carburetor by the engine. A warming medium heated up by the engine can be passed along the outer surfaces of the carburetor separate from the combustion air stream.

Abstract: The invention is directed to a two-stroke internal combustion engine for handheld portable tools such as a motor-driven chain saw with the engine having a piston guided in a cylinder. The base of the piston is rotationally symmetrical and delimits a combustion chamber. An injection valve is mounted in the cylinder wall opposite an exhaust opening for exhaust gases. The injection valve injects fuel toward the piston base at an angle of less than 90.degree.. At least one overflow opening is arranged in the cylinder wall between the exhaust opening and the injection valve. Combustion air flows in through the overflow opening with the downward movement of the piston. The injection jet is directed opposite to the flow direction of the entering combustion air. The injection jet is directed for the most part to the half of the piston base which is disposed away from the exhaust opening and the injection opening is the last opening to be closed by the piston travelling toward top dead center.

Abstract: The invention is directed to a fuel injection pump for a two-stroke engine mounted in a work apparatus such as a motor-driven chain saw. The injection pump includes a pneumatic drive chamber which is charged with the crankcase pressure of the two-stroke engine. A membrane mounted in the drive chamber transmits the pulses of the crankcase pressure to a pump piston which moves into a pump chamber against the force of a leaf spring. The leaf spring is configured as a leaf spring packet of individual leaf springs in order to obtain an adaptation of the injected fuel quantity to the position of the throttle flap of the engine.

Abstract: The invention is directed to a fuel injection pump for a two-stroke engine which is especially for portable handheld tools such as motor-driven chain saws or the like. A pneumatic drive chamber is provided in the pump housing which is partitioned by a membrane into a pulse chamber charged by the crankcase pressure and a return chamber. A membrane plate holds the membrane and charges a pump piston which plunges into a pump cylinder for injecting fuel when a pulse is present in the pulse chamber. The pump piston draws fuel in by suction during a return stroke of the membrane plate into a start position determined by a stop. The stop is configured so as to be displaceable in the direction of the stroke of the piston in dependence upon temperature in order to obtain an adaptation of the injected quantity of fuel to the operating temperature of the engine. In this way, the stroke of the pump piston can be varied and therefore also the quantity of fuel supplied by the pump.