Abstract: A blow-by gas recirculation device that, while having a structure in which a passage for blow-by gas is in a head cover and an oil separator, an increase in size of an engine is suppressed and the risk of the freezing is mostly avoided by shortening the length of an external pipe for the blow-by gas. Therefore, the blow-by gas recirculation device guides blow-by gas from a crankcase to an intake passage through an in-cover gas passage formed inside a head cover. An oil separator that traps and removes oil from the blow-by gas is attached to the inside of the head cover. A pressure regulating valve is provided on the outlet side of the in-cover gas passage in the head cover. A separator outlet, which is an outlet for the blow-by gas in the oil separator, is overlapped on a blow-by gas inlet portion of the pressure regulating valve.

Abstract: A blow-by gas recirculation device that, while having a structure in which a passage for blow-by gas is in a head cover and an oil separator, an increase in size of an engine is suppressed and the risk of the freezing is mostly avoided by shortening the length of an external pipe for the blow-by gas. Therefore, the blow-by gas recirculation device guides blow-by gas from a crankcase to an intake passage through an in-cover gas passage formed inside a head cover. An oil separator that traps and removes oil from the blow-by gas is attached to the inside of the head cover. A pressure regulating valve is provided on the outlet side of the in-cover gas passage in the head cover. A separator outlet, which is an outlet for the blow-by gas in the oil separator, is overlapped on a blow-by gas inlet portion of the pressure regulating valve.