| 摘要 |
A reduced volume scavenging system for a two cycle engine embodying a duplex cylinder having an upper cylinder bore (18, 19) and a reduced-diameter lower cylinder bore (18', 19'). The lower bore (18', 19') communicates with a crankcase (88) that houses a crankshaft (62), connecting rod(s) (64) and engine lubricating oil. A fixed sleeve (16) lines the upper cylinder bore (18, 19) and extends up into the cylinder head (12). A piston (40) disposed for reciprocating motion within the fixed sleeve (16) has an attached cylindrical, reciprocating sleeve (50) that extends down into the lower cylinder bore (18', 19') and moves with the piston (40). The reciprocating sleeve (50) has compression rings (50R) that seal the lower bore (18', 19') and the crankcase (88) against blowby gases that might contaminate the oil. The fixed sleeve (16) has an intake opening (17) in registry with an inlet port (25) in the upper cylinder bore (18, 19) for admission of fresh air-fuel mixture.
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