| 摘要 |
A crankcase scavenged and lubricated four-stroke engine ( 1 ) comprising especially: a mixture-preparation device ( 15 ) for supplying an air-fuel-lubricant mixture; an intake channel ( 16 ) connecting to the crankcase or cylinder to supply at least air ( 13 ) to the crankcase volume ( 12 ); an overflow channel ( 17 ) connecting to the crankcase or cylinder and to the intake opening ( 7 ) with intake valve ( 8 ) to supply to the intake at least air and lubricant from the crankcase volume; a valve drive assembly ( 18 ) driven by a crankshaft ( 4 ) for actuating the intake valve ( 8 ) and the exhaust valve ( 10 ); a valve drive assembly housing ( 19, 20, 21, 21', 22 ) comprising one or more sections ( 19, 20, 21, 21', 22 ) which is/are separate from the crankcase but in communication exclusively with the crankcase volume via at least one small size passage ( 23, 24, 25, 26, 27 ), and each section ( 19, 20, 21, 21', 22 ) of the valve drive assembly housing has a lowest part situated closer to the combustion chamber, than the lowest part of the crankcase.
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