| 摘要 |
A vertical-type multicylinder engine includes a plurality of combustion chambers, an inlet muffler having a plurality of air intake passages, and a blow-by gas entry opening for introducing blow-by gas into the muffler, and a plurality of throttle valve devices provided downstream of the intake passages and upstream of the valve devices in corresponding relation thereto. The inlet muffler has a plurality of blow-by gas distributing paths that are formed inside the muffler to distributively direct the blow-by gas introduced via the blow-by gas entry opening to the corresponding throttle valve devices. Thus, the entry opening, distributing paths and intake passages of the muffler and the throttle valve devices together define a structure for returning the blow-by gas to an upstream portion of the engine intake system. The distributing paths have different sizes that become progressively greater as the respective distances, from the blow-by gas entry opening, of the paths increase. The blow-by gas returning structure thus formed serves to minimize inter-cylinder differences in the amounts of blow-by gas flowing into the individual throttle valve devices and hence in combustion conditions in the combustion chambers.
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