| 摘要 |
The invention relates to a two-stroke engine for a portable handheld work apparatus such as a motor chain saw. The combustion chamber (3), which is configured in a cylinder (2), is delimited by a piston (5) which drives a crankshaft (7) rotatably journalled 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 into the combustion chamber (3) via an entry window (12, 15) lying in the cylinder wall (16); whereas, the second end (19) of this transfer channel (14) is open toward the crankcase (4). The transfer channel (14) is connected between its ends (19, 20) to an air channel (22a, 22b) via a check valve (21). The air channel (22a, 22b) supplies essentially fuel-free gas via a throttle (31) having an adjustable throttle element (33). A mixture-preparation device (8) is provided for the air/fuel mixture downstream of an air filter (42) in the flow direction of the combustion air. The air/fuel mixture is supplied via an inlet (11) to the crankcase (4). In order to meter clean air to the air channels in a controlled manner, an adjustable throttle element (33) is mounted in a throttle channel (36) of an independent throttle housing (31) and the throttle channel (36) is connected upstream of the throttle element to the clean space (51) of the air filter (42) connected ahead of the mixture-preparation device (8). |
