Abstract: A manually guided, motor-driven implement is provided that has a housing for a motor, especially an internal combustion engine, that drives a working tool of the implement. In order for a power chain saw to mount a handle on the housing of the motor in a vibration dampening manner such that due to the mounting a structurally prescribed dampening frequency range is effected, one or more hydraulic mounts are disposed between the handle and the motor of the power chain saw.

Abstract: A portable hand-guided work apparatus (1), such as a motor-driven chain saw, cutoff machine or the like, includes an internal combustion engine (2) and an air filter (10). At least one air channel (8) and an intake channel (7) are provided which fluidly connect the internal combustion engine (2) to the clean side of the air filter (10). The intake channel (7) is configured at least partially in a carburetor (9). The air channel (8) opens at an air channel opening (13, 13′, 13″) and the intake channel (7) opens at an intake opening (12) at the clean side of the air filter (10). Air channel opening (13, 13′, 13″) and intake opening (12) open spatially separate from each other at the clean side of the air filter (10).

Abstract: A two-cycle engine in a portable, manually-guided implement, such as a power chain saw, a cut-off machine, a brush cutter, or the like, is provided. The cylinder has a combustion chamber that is delimited by a reciprocating piston that via a connecting rod drives a crankshaft that is mounted in a crankcase so as to be rotatable about a crankshaft axis. The cylinder has an outlet for conveying exhaust gases out of the combustion chamber, with the outlet having an axis of the channel thereof. The cylinder also has an inlet for supplying a fuel/air mixture to the crankcase. By means of at least two transfer channels, the fuel/air mixture is conveyed out of the crankcase and into the combustion chamber, with the transfer channels being disposed symmetrically relative to the axis of the channel of the outlet.

Abstract: A two-cycle engine is provided for a portable, manually-guided implement and has a cylinder in which is formed a combustion chamber delimited by a reciprocating piston. The engine has an inlet for fuel/air mixture, an outlet out of the combustion chamber for exhaust gas, and four transfer channels that are arranged mirror symmetrically relative to a mirror plane, open into the cylinder via inlet windows, and fluidically connect the crankcase with the combustion chamber as a function of the piston position. Two transfer channels are close to the outlet and two are remote from the outlet. The transfer channels have a connecting portion to the crankcase, an ascending portion that is substantially parallel to the longitudinal axis of the cylinder, and an opening-out portion into the combustion chamber.

Abstract: A method is provided for producing a cylinder in a two-cycle engine. The cylinder bore is first machined as a preparation for the provision of a coating. The thereby resulting window edges that surround an inlet window are then at least partially chamfered. The cylinder bore is consequently provided with the coating, which at least partially overlaps the chamfered window edge. There thereby results in the region of the window edge a location of least spacing relative to the axis of the transfer channel. The piston liner or gliding surface is finally machined to a finished dimension such that in the region of the chamfered and coated window edge or corner there is formed a coating edge having a wall spacing relative to the location of least spacing, which such wall spacing having a maximum value of 0.7 mm.

Abstract: A muffler arrangement includes an exhaust-gas muffler (4), which is subdivided into an inlet space (9) and an outlet space (10). An exhaust-gas stub (3) of an internal combustion engine (1) opens into the inlet space (9). Exhaust gas is conducted from the outlet space (10) into an air channel (15) via an exhaust-gas outlet (12). The air channel (15) is formed between the housing (4c) of the exhaust-gas muffler (4) and an outer cover (16) and extends along a side of the exhaust-gas muffler (4). A cooling-air component flow (18) is branched from a cooling-air flow of a cooling-air blower (5) and enters at a first end (25) of the air channel (15). The cooling-air component flow (18) exits again at the other second end (35) of the air channel (15).

Abstract: The invention relates to an intake system (1) for the combustion air (2) of an internal combustion engine (3) in a portable handheld work apparatus (4). The intake system (19) includes a filter housing (5) having an air filter (6) for purifying the combustion air (2). The clean space (8) of the air filter (6) is fluidly connected to an outlet opening (10) of the filter housing (5). The outlet opening (10) communicates with a carburetor (7) of the engine (3). A centrifugal-force separator (13) is mounted forward of the air filter (5) for separating large amounts of dust in the inducted combustion air (2). The separator (13) is so positioned ahead of the filter housing (5) that a central core flow (14) of the separator has a lower particle density (15) and is supplied to the filter (6). A tangential flow (16) surrounds the central core flow (14) in the interior of the separator (13).

Abstract: A portable handheld work apparatus such as a motor-driven chain saw includes a housing (6) of a drive unit (2). The following are mounted in the housing (6): an internal combustion engine (3), a carburetor (4) for fuel metering and an air filter (5) as well as a fuel tank (8). The air filter (5) is mounted ahead of the carburetor in the flow direction of the fresh air flow. A largest possible filter action is obtained with a compact configuration in that a housing (10) of the air filter (5) lies at least partially in a space between the carburetor (4) and the fuel tank (8).

Abstract: A manually guided implement having an internal combustion engine is provided. A fuel/air mixture is supplied to the internal combustion engine via a diaphragm carburetor. The engine is cooled by a cooling fan that is driven by the internal combustion engine and that generates an air stream. The diaphragm carburetor has a fuel-filled control chamber with a control diaphragm which on that side facing away from the control chamber delimits a compensation chamber. To limit speed, a control pressure line is provided between the compensation chamber and the air stream generated by the cooling fan.

Abstract: The invention relates to a portable handheld work apparatus including a chain saw, a vacuum/blower apparatus or the like. The work apparatus has a handle (2) for carrying and guiding the work apparatus (1). Thumb supports (4, 5) are provided on both sides with respect to the longitudinal axis (3) of the handle (2).

Abstract: A valve drive having a rocker arm mounted on a cylinder head is provided. One end of the rocker arm is actuated by a push rod to actuate a valve stem of a poppet valve that engages the other end of the rocker arm, which is pivotably held between its ends on a support pin that extends into the cylinder head, with a spherical mounting being provided between the support pin and the rocker arm. Provided on that side of the rocker arm remote from the cylinder head is a bolt head for adjusting the bearing spacing between the rocker arm and the cylinder head for adjusting valve play. To prevent unintended adjustment of the bolt head, the latter cooperates with a rotation preventing element that has an arresting portion that engages the bolt head, and a support portion that conveys the adjustment moment away.

Abstract: A cam drive is provided for a valve control of a mixture-lubricated internal combustion engine that has a cylinder, and a cylinder head in which is disposed a poppet valve which is actuated by a pivotable rocker arm. Mounted in a cam chamber is a control cam that is driven by the crankshaft of the engine and on the cam path of which rests a drag lever that transfers the cam lift to the rocker arm. To achieve a reliable mixture lubrication, a flow guidance element is disposed in the annular chamber between the peripheral wall of the cam chamber and the maximum diameter of the path of a cam nose. The flow guidance element is provided with a flow edge that is disposed adjacent to the drag lever in the vicinity of the path diameter of the cam nose.

Abstract: An exhaust gas muffler for an internal combustion engine is provided, especially for a portable implement. The muffler has a housing with at least two parts, an inlet for exhaust gas issuing from the engine, and an outlet for discharge of processed exhaust gas. A partition is disposed within the housing between the inlet and outlet and divides the housing into two chambers. The partition is provided with a first opening in which a catalyzer is mounted, and at least one bypass opening. The muffler also has a respective valve member for each bypass opening. Below a specified temperature the bypass opening is closed. The valve member is controlled by the temperature in the muffler in such a way that when a prescribed operating temperature is exceeded, the bypass opening is opened.

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: A diaphragm carburetor for an internal combustion engine of a portable hand-held working tool has a housing with a control chamber. A suction channel extends through the housing and has a venturi section. An inlet valve is connected to the control chamber and supplies the control chamber with fuel. A main valve channel connects the control chamber to the venturi section of the suction channel. A check valve is positioned in the main valve channel adjacent to the control chamber and closes the main valve channel toward the control chamber. The main valve channel has a straight and elongate portion extending from the check valve into the venturi section and projecting into the suction channel.

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.

Abstract: An actuating device for a decompression valve of an internal combustion engine with a cable starter, wherein the decompression valve is positioned within the cylinder of the internal combustion engine and comprises a valve member biased into its closed position, has a transmission lever having a longitudinal extension and being rotatable about its longitudinal axis. The transmission lever has a first and a second end. A cable drum for receiving the starter cable of the cable starter is provided. The cable drum has an axis of rotation about which the cable drum is rotated when the starter cable is pulled. The longitudinal axis of the transmission lever is perpendicular to the axis of rotation of the cable drum and spaced from the rotational plane of the cable drum.

Abstract: The invention is directed to a start-assist device on a membrane carburetor of an internal combustion engine in a motor-driven chain saw which is to be started manually. The carburetor includes a control chamber delimited by a control membrane. The control chamber is supplied with fuel from a fuel tank via control valve. The control valve is opened by the control membrane when the underpressure builds up in the control chamber so that fuel flows in. This fuel is supplied to the air-inducting intake channel via an idle nozzle and a main nozzle. The fuel feed system further has an outlet for vapor bubbles or the like. A pump which is driven indirectly from the start operation is provided and has a suction connection connected to the outlet in order to ensure, with few start attempts, a reliable start of the engine independently of the temperature state of the engine and other influences.