| 摘要 |
A low emission two-cycle internal combustion engine for powering a portable tool is provided. The two-cycle engine comprising a cylinder block containing two parallel cylinders adjacent to each other receiving two reciprocating pistons. One cylinder in cooperation with the power piston, operates as the power source. The second cylinder in cooperation with the slave piston, operates as a volumetric fuel pumping system. Both cylinders centerlines lying in a plane perpendicular to a crankshaft. The cylinder block is disposed over an engine block containing the crankshaft and a crankcase. The two pistons are connected by a connecting rod to a common crankpin. The kinematics of this engine leads to a considerable advance of the slave piston in relation to the power piston, resulting in a significant higher pressure within the pump cylinder than into the power cylinder during the compression period. The combustion gasses are evacuated by pure air compressed into the crankcase through the scavenging ports. After the exhaust port closes, a rich fuel/air mixture is progressively introduced into the power piston by the pumping action of the slave piston. This fuel/air mixture is introduced into the combustion chamber of the power cylinder through a fuel transfer port communicating the upper portion of both cylinders and through a unidirectional valve located at the end of such transfer port. Because the injection occurs after the piston has closed off the exhaust port, virtually no unburned fuel escapes, therefore, HC emissions are greatly reduced and fuel economy is enhanced.
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