Two-stroke motor for a hand-held tool such as a power saw or brush cutter comprises transfer ports connected to an air duct at different times during operation of the motor

摘要

Two-stroke motor (1), especially in a hand-held tool such as a power saw, brush cutter, etc. comprises a cylinder (2) containing a combustion chamber (3) defined by a reciprocating piston (5). The piston drives a crankshaft (7) rotatably mounted in a crankcase (4) via a connecting rod (6). In pre-determined positions of the piston the combustion chamber is connected to the crankcase via at least two transfer ports (11, 13). The motor is provided with at least one air duct (15) which in pre-determined positions of the piston is connected to at least two transfer ports. The transfer ports are connected to the air duct at different times during operation of the motor. Preferred Features: On the upward stroke of the piston the connection between a transfer port (11) near the outlet and the air duct begins to open before the connection between a transfer port (13) further away from the outlet and the air duct.