| 摘要 |
PROBLEM TO BE SOLVED: To prevent oil from being sucked into a cylinder by interposing a variable venturi type variable valve opening and closing corresponding to intake air quantity between a throttle valve and an air meter on an upstream side of this throttle valve and connecting a passage for sucking blow by-gas with a venturi part of the variable valve. SOLUTION: On a passage for intake introduction 23 of an intake device 3, an air cleaner 28, an air meter 29, a variable valve 30 and a throttle valve 31 are disposed from an upstream side. Between the air meter 29 and the variable valve 30, a sub-surge tank 25 is connected. As the variable valve 30, a variable venturi type variable valve having a bottomed cylindrical negative pressure piston is used. At this time, at a portion opposed to a bottom surface of the negative pressure piston in the valve body, that is, a venturi part, a blow by-gas introduction port is opened and a tip part of a hose 13 for deriving blow by-gas is connected at this introduction port. As a result, oil mist within a crankcase is prevented from being sucked together with blow by-gas into a cylinder and injurious components in exhaust gas is reduced.
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