Abstract: A two-stroke engine has a cylinder and a piston reciprocating in the cylinder and delimiting a combustion chamber. The piston has at least one piston recess. A crankshaft is rotatably arranged in a crankcase connected to the cylinder. A connecting rod connects piston and crankshaft. Transfer channels connect the crankcase to the combustion chamber in pre-defined piston positions. The transfer channels each have a transfer port opening into the combustion chamber. A device for supplying fuel and an air channel supplying combustion air are provided. In predetermined piston positions, the air channel is connected by the piston recess to the transfer ports. The air channel opens into the cylinder bore opposite the exhaust for the exhaust gases. The air channel, the piston recess, and the transfer channels define an air passage that provides approximately uniform distribution of air from the air channel into the transfer channels.

Abstract: A two-stroke engine has a cylinder and a piston reciprocating in the cylinder and delimiting a combustion chamber. The piston has at least one piston recess. A crankshaft is rotatably arranged in a crankcase connected to the cylinder. A connecting rod connects piston and crankshaft. Transfer channels connect the crankcase to the combustion chamber in pre-defined piston positions. The transfer channels each have a transfer port opening into the combustion chamber. A device for supplying fuel and an air channel supplying combustion air are provided. In predetermined piston positions, the air channel is connected by the piston recess to the transfer ports. The air channel opens into the cylinder bore opposite the exhaust for the exhaust gases. The air channel, the piston recess, and the transfer channels define an air passage that provides approximately uniform distribution of air from the air channel into the transfer channels.

Abstract: An exhaust-gas muffler includes a muffler housing (2) having an inlet opening (3) and an outlet (4). The exhaust-gas muffler is especially for the internal combustion engine in a portable handheld work apparatus. At least one attenuating space (5, 5?, 5?) is configured in the exhaust-gas muffler (1). The exhaust-gas muffler (1) includes at least one resonance pipe (6) to increase power and to reduce the hydrocarbon emissions. The resonance pipe (6) is fluidly connected to the inlet opening (3) and the resonance pipe leads to a backflow of exhaust gases into the combustion chamber (22). For a simple manufacture, it is provided that the exhaust-gas muffler (1) includes lower and upper half shells (8, 7) via which the resonance pipe (6) is at least partially delimited.

Abstract: A two-stroke engine (1) has a combustion chamber (3) disposed in a cylinder (2). The combustion chamber (3) is delimited by a reciprocating piston (5). The piston (5) drives a crankshaft (7) via a connecting rod (6) and the crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) has an intake channel (8) for the supply of fuel into the crankcase (4), an outlet (13) for exhaust gases from the combustion chamber (3) and an air channel (10) for the supply of substantially fuel-free air. A throttle element (18) is mounted in the air channel (10). At pregiven positions of the piston (5), the crankcase (4) is connected via at least one transfer channel (14) to the combustion chamber (3).

Abstract: A two-stroke engine (1) has a combustion chamber (3) disposed in a cylinder (2). The combustion chamber (3) is delimited by a reciprocating piston (5). The piston (5) drives a crankshaft (7) via a connecting rod (6) and the crankshaft (7) is rotatably journalled in a crankcase (4). The two-stroke engine (1) has an intake channel (8) for the supply of fuel into the crankcase (4), an outlet (13) for exhaust gases from the combustion chamber (3) and an air channel (10) for the supply of substantially fuel-free air. A throttle element (18) is mounted in the air channel (10). At pregiven positions of the piston (5), the crankcase (4) is connected via at least one transfer channel (14) to the combustion chamber (3).

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: 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: An internal combustion engine, especially of a two-stroke engine in a portable handheld work apparatus, includes an outlet (27) for the exhaust gases which is fluidly connected with at least one inlet opening (13, 14) in an exhaust-gas muffler (1). At least one resonance pipe (6, 7) is mounted in flow direction between the outlet (27) from the engine (20) and the inlet opening (3, 5) into the exhaust-gas muffler (1) in order to obtain a good noise attenuating result and simultaneously make possible an advantageous, space-saving mounting of the engine (20).

Abstract: An exhaust-gas muffler includes a muffler housing (2) having an inlet opening (3) and an outlet (4). The exhaust-gas muffler is especially for the internal combustion engine in a portable handheld work apparatus. At least one attenuating space (5, 5′, 5″) is configured in the exhaust-gas muffler (1). The exhaust-gas muffler (1) includes at least one resonance pipe (6) to increase power and to reduce the hydrocarbon emissions. The resonance pipe (6) is fluidly connected to the inlet opening (3) and the resonance pipe leads to a backflow of exhaust gases into the combustion chamber (22). For a simple manufacture, it is provided that the exhaust-gas muffler (1) includes lower and upper half shells (8, 7) via which the resonance pipe (6) is at least partially delimited.

Abstract: The invention relates to a two-cycle engine for a drive engine in a portable, manually operated tool. The combustion chamber formed in a cylinder is delimited by a piston that moves up and down, whereby the piston, by means of a connecting rod, drives a crankshaft rotatably mounted in a crankcase. The combustion chamber has an outlet for removing waste gases, and provided for supplying a fuel/air mixture prepared by a mixture preparation device, and combustion air, are gas-supplying channels that open into the combustion chamber. In order to reduce scavenging losses, it is provided that for the entire duration of the gas exchange exclusively air flows in the area near the outlet and exclusively fuel/air mixture flows out of the crankcase in the area further away from the outlet.

Abstract: The invention relates to a two-stroke engine in the form of a drive motor in a motor-driven chain saw or like portable handheld work apparatus. A combustion chamber (4) is provided in a cylinder (2) of the engine and is delimited by a piston (1). The piston (1) drives a crankshaft (6) via a connecting rod (5) and the crankshaft (6) includes a crankweb (7). The combustion chamber (4) is connected via an outlet to an exhaust-gas muffler. A fresh mixture is supplied to the combustion chamber (4) from the crankcase (3) via a transfer channel (10). The entry of the fresh mixture takes place via the crankcase (3). Also, an air channel (21) is provided for supplying fuel-free air. To reduce the scavenging losses, the air channel (21) is connected via a storage space (20) to the crankcase (3). The transfer channel (10) is either connected directly via a valve (23) to the crankcase or indirectly via the storage space (20).

Abstract: An exhaust gas control mechanism for a two-stroke engine is provided. A first housing chamber is in communication with a discharge window of the cylinder of the engine, while a second housing chamber has the exhaust gases flowing therethrough into an exhaust gas outlet. A flow communication establishes a controlled communication of flow of exhaust gas from the first chamber to the second chamber. A valve is provided for controlling the flow communication, wherein such valve, if initially open, closes upon partial opening of the discharge window and after a given period of time again opens.

Abstract: A two-stroke engine for a portable two-stroke engine in a portable handheld work apparatus includes a combustion chamber (3) formed in a cylinder (2). The combustion chamber (3) is delimited by the piston (5) which drives the crankshaft (7) via a connecting rod (6). The two-stroke engine includes several transfer channels (14), which, referred to a symmetry plane (49), lie on opposite sides (47, 48) with the plane partitioning approximately the outlet (10). The transfer channels (14) connect the crankcase (4) to the combustion chamber (3). A first end (20) of each transfer channel (14) opens via an entry window (12, 15) into the combustion chamber (3) and the second end (19) of each transfer channel opens to the crankcase (4). Each transfer channel (14) is connected, between its ends (19, 20), to an air channel (22a, 22b) via a membrane valve (21). Air is supplied by the air channel (22a, 22b) via an adjustable throttle (31, 32).

Abstract: The invention relates to a two-stroke engine in the form of a drive motor in a motor-driven chain saw or like portable handheld work apparatus. A combustion chamber (4) is provided in a cylinder (2) of the engine and is delimited by a piston (1). The piston (1) drives a crankshaft (6) via a connecting rod (5) and the crankshaft (6) includes a crankweb (7). The combustion chamber (4) is connected via an outlet to an exhaust-gas muffler. A fresh mixture is supplied to the combustion chamber (4) from the crankcase (3) via a transfer channel (10). The entry of the fresh mixture takes place via the crankcase (3). Also, an air channel (21) is provided for supplying fuel-free air. To reduce the scavenging losses, the air channel (21) is connected via a storage space (20) to the crankcase (3). The transfer channel (10) is either connected directly via a valve (23) to the crankcase or indirectly via the storage space (20).

Abstract: A hand-held working tool has a housing and an internal combustion engine arranged in the housing and comprising a crankshaft and an air filter. A tool is driven by the crankshaft of the internal combustion engine. A fan housing is attached to the engine housing and has an air inlet. A fan wheel is arranged in the fan housing and is driven by the crankshaft of the internal combustion engine to supply cooling air, sucked in through the air inlet, to the internal combustion engine. The fan housing has a bottom extending radially to the crankshaft. The bottom and a side of the fan wheel facing the bottom define a chamber in the fan housing. The bottom has a combustion air outlet. A combustion air channel is connected to the combustion air outlet and to the air filter. The combustion air outlet is axially supplying combustion air from the chamber through the combustion air channel into the air filter of internal combustion engine.

Abstract: The invention relates to a two-stroke engine in a portable handheld work apparatus such as a motor-driven chain saw or the like. A combustion chamber (3) is formed in the cylinder (2) of the two-stroke engine (1). The combustion chamber (3) is delimited by the piston (5). The piston (5) drives the crankshaft (7) via a connecting rod (6) and the crankshaft (7) is rotatably journalled in the crankcase (4). The two-stroke engine includes several transfer channels (14), which, referred to a symmetry plane (49), lie on opposite-lying sides (47, 48) with the plane partitioning approximately the outlet (10). The transfer channels (14) connect the crankcase (4) with the combustion chamber (3). A first end (20) of each transfer channel (14) opens via an entry window (12, 15) into the combustion chamber (3); whereas, the second end (19) of each transfer channel opens to the crankcase (4). Each transfer channel (14) is connected, between its ends (19, 20) to an air channel (22a, 22b) via a membrane valve (21).

Abstract: The invention relates to a two-stroke engine which operates as a drive motor in a portable work apparatus such as a motor-driven chain saw. The two-stroke engine has a combustion chamber (3) which is formed in a cylinder (2) and is delimited by a piston (5) which moves up and down in the cylinder. The piston drives via a connecting rod (6) a crankshaft (7) which rotates in a crankcase (4). The crankcase (4) is connected to the combustion chamber (3) via a transfer channel (14). A first end (20) of the transfer channel (14) opens via an entry window (12) into the combustion chamber (3) and the second end (19) of the transfer channel (14) opens into the crankcase (4). The entry window (12) lies in the cylinder wall (16) and is controlled by the piston (5). The transfer channel (14) is connected to a gas channel (22) between its ends (19, 20). An essentially fuel-free gas flow (40) flows via a check valve (21) from the gas channel (22) and flows into the transfer channel (14).

Abstract: A two-stroke internal combustion engine for a hand-guided working tool has a cylinder with a cylinder wall and a piston reciprocating in the cylinder and defining a combustion chamber with the cylinder wall. Transfer parts, each having an outlet window, for introducing combustion air and fuel into the combustion chamber are provided. The outlet windows are cut into the cylinder wall for connecting the transfer parts to the combustion chamber. The outlet windows have limiting edges extending parallel to a central cylinder axis of the cylinder and are located within an inner mantle surface of the cylinder wall. The outlet windows have a window width measured in a circumferential direction of the inner mantle surface. The transfer parts have a channel width measured in the circumferential direction of the inner mantle surface, whereby the window width is greater than the channel width. The transfer parts have a transition portion into the outlet windows.