Separator device for use in a system for the recirculation of blow-by gases of an internal combustion engine

A separator device for a system for recirculation of blow-by gases of an internal-combustion engine comprises an elongated casing (2) defining a separation chamber (3) with an inlet (4) at one end, for communication with the crankcase, an outlet (5) at the second end, for communication with the intake system of the engine, and an end wall with at least one draining sump (6) for draining the liquid separated in the separation chamber (3) for return of the separated liquid into the crankcase. Associated to said inlet (4) is an open/close element with flexible flap (7) that opens when the crankcase is in overpressure with respect to the separation chamber (3), whereas associated to each draining sump (6) is a membrane open/close element (6b) that, in the aforesaid condition of overpressure, closes, whereas, when the crankcase is in negative pressure, opens, enabling return of the liquid separated and collected inside each draining sump (6) into the crankcase. In order to enable maximum efficiency of separation of the oil contained in the flow of blow-by gases that traverses the separation chamber (3), said chamber is without diaphragms set transversely with respect to the longitudinal direction of the device, and has one or more inner walls (10) arranged parallel to the longitudinal direction of the device in such a way that the drops of oil contained in the gas flow separate by a phenomenon of adhesion to the aforesaid longitudinal walls. Said walls can, for example, be defined by a single sheet, for example in the form of a mesh folded in bellows fashion.