| 摘要 |
PURPOSE:To surely prevent the oil from flowing out of a crankcase into a suction air passage by a method wherein the blow-by gas in the crankcase is recirculated on the downstream side of a throttle valve in the suction air passage during light load running, while recirculated on the upperstream side of an air flow meter in the suction air passage during heavy load running. CONSTITUTION:During light load running with no supercharging, a PCV valve 16 is open and at the same time a second communicating passage 17 side is open by means of a two-way valve 21. Accordingly, the blow-by gas in a crankcase 3 is sucked through a first communicating passage 15 in a suction air passage 6 downstream from a throttle valve 7, while air is fed from the suction air passage 6 upstream from the throttle valve 7 through the second communicating passage 17 into the crankcase 7 in order to ventilate the crankcase 7. On the other hand, during heavy load running when a supercharger 8 is in operation, said valve 16 is closed and the valve 21 is changed-over to a third communicating passage 18 open side. Accordingly, the blow-by gas is sent through the third communicating passage 18 and an oil separator 24 to a suction air passage upstream from an air flow meter 10. |
