Patent ID: 8813731

Claim:
A blow-by gas refluxing device provided for an engine system including an engine, an intake air passage, and a supercharger and a throttle valve each disposed in the intake air passage, the throttle valve being disposed on a downstream side of the supercharger in the intake air passage, the blow-by gas refluxing device comprising: a blow-by gas refluxing passage configured to allow blow-by gas produced in the engine to flow into the intake air passage and to be refluxed into the engine; and an intake air bypass passage connecting between an upstream side and a downstream side of the supercharger in the intake air passage; wherein: the blow-by gas refluxing passage comprises a first blow-by gas refluxing passage and a second blow-by gas refluxing passage; the first blow-by gas refluxing passage has an inlet and an outlet, the inlet being connected to at least one of a cylinder block and a cylinder head cover of the engine and the outlet being connected to the intake air bypass passage; at least one of the first blow-by gas refluxing passage and the intake air bypass passage has a first backflow prevention device disposed therein for preventing the blow-by gas from flowing from the first blow-by gas refluxing passage into the at least one of the cylinder block and the cylinder head cover; the second blow-by gas refluxing passage has an outlet connected to the intake air passage on the downstream side of the throttle valve and has a second backflow prevention device disposed therein for preventing the blow-by gas from flowing from the second blow-by gas refluxing passage into the at least one of the cylinder block and the cylinder head cover; and the first backflow prevention device comprises a jet pump capable of producing a negative pressure in the intake air bypass passage, and the outlet of the first blow-by gas refluxing passage is connected to the intake air bypass passage via the jet pump.