The oil mist separator includes a separator case, a gas inlet portion, a gas outlet portion, a separating component and a wall portion. The separator case is formed with a gas flow path. The gas inlet portion introduces the blow-by gas into the separator case on one side of the gas flow path. The gas outlet portion discharges the blow-by gas out of the separator case on the other side of the gas flow path. The separating component is disposed in the separator case and located between the gas inlet and outlet portions to separate the oil mist from the blow-by gas when the blow-by gas flows along the gas flow path. The wall portion is erected on the bottom wall in the separator case and faces the gas outlet portion at a position leaning toward the gas outlet portion between the separating component and the gas outlet portion.

The oil mist separator includes a separator case, a gas inlet portion, a gas outlet portion, a separating component and a wall portion. The separator case is formed with a gas flow path. The gas inlet portion introduces the blow-by gas into the separator case on one side of the gas flow path. The gas outlet portion discharges the blow-by gas out of the separator case on the other side of the gas flow path. The separating component is disposed in the separator case and located between the gas inlet and outlet portions to separate the oil mist from the blow-by gas when the blow-by gas flows along the gas flow path. The wall portion is erected on the bottom wall in the separator case and faces the gas outlet portion at a position leaning toward the gas outlet portion between the separating component and the gas outlet portion.

A positive crankcase ventilation (PCV) system includes: an oil separator separating oil from blow-by gases; a PCV valve allowing the blow-by gases from which the oil has been separated by the oil separator to flow into intake ports of a cylinder head; a PCV passage vertically extending from the PCV valve; a PCV chamber connected to the PCV passage; and a plurality of bypass passages branching off from the PCV chamber to the intake ports, respectively.

An engine assembly includes an engine, an intake assembly, and an air-oil separator. The engine defines a combustion chamber and a crankcase. The intake assembly includes an intake manifold wherein the intake manifold is in fluid communication with the combustion chamber. The air-oil separator defines an internal passageway having a separator volume and further defining an inlet and outlet in fluid communication with the separator volume. The inlet of the air-oil separator may be in fluid communication with the crankcase while the outlet of the air-oil separator may be in fluid communication with the intake manifold. The air-oil separator further includes a fine separator disposed across the internal passageway proximate to the inlet wherein the fine separator includes a curved backplate and a front plate.

A separator includes: a filter device that receives oil-containing blow-by gases from an engine and separates at least a portion of oil from the oil-containing blow-by gases, the oil-containing blow-by gases being generated by the engine; a screen extending from the filter device in a direction transverse to a vertical direction with respect to the engine; a drain hole vertically penetrating below the screen to allow the separated oil to be discharged by gravity; and a gas outlet disposed above the screen to discharge the separated blow-by gases.

A utility vehicle includes: an engine which is a drive source; a catch tank configured to perform a gas-liquid separation of a blow-by gas generated in the engine; a first breather passage configured to deliver the blow-by gas, which is discharged from the engine, to the catch tank; a second breather passage configured to supply a gas component, which has been separated in the catch tank, to an air intake system of the engine; and a return passage configured to return a liquid component, which has been separated in the catch tank, to the engine. The catch tank is disposed above a cylinder head covering. A breather outlet port, with which the first breather passage is fluid connected, and an oil return port, with which the return passage is fluid connected, are formed in an upper surface of the cylinder head covering.

A blow-by gas treating device has an oil separator. A tubular attachment portion is disposed at a discharge port of the oil separator. A PCV valve is inserted in the attachment portion. The PCV valve includes an inflow hole, a discharge hole, a flow rate regulating portion, and a stopping portion. The stopping portion is located closer to the inflow hole than to the flow rate regulating portion. The stopping portion has a dimension greater than the inner diameter of the attachment portion in a direction perpendicular to the central axis of the attachment portion. The flow rate regulating portion is surrounded by the attachment portion. The stopping portion is arranged in the space defined by the oil separator.

A cylinder head cover includes a main body and a side projection portion. The main body is provided so as to cover a cylinder head, and collects a blowby gas. The side projection portion discharges the blowby gas toward an intake passage. The cylinder head cover includes a cover gas passage through which the blowby gas flows from a main body gas passage to an outlet of the side projection portion. A minimum passage cross-sectional area portion of the cover gas passage is provided not in the side projection portion but in the main body gas passage. The main body has a hole or a projection branch passage at a position of the main body gas passage that is downstream of the minimum passage cross-sectional area portion. The main body, the side projection portion, and the hole or the projection branch passage are integrally molded.

An engine includes: a throttle body that is joined to an intake port and that makes a butterfly valve within an intake path actuate based on driving force of an electric actuator so as to adjust an opening degree of the intake path; a receptor that extends from the throttle body to a direction distant from the throttle body above a crankcase and that receives the electric actuator therein; and a supporting piece that extends from the receptor to the direction distant from the throttle body and that is supported on the crankcase. Accordingly, in the engine, it is possible to alleviate the influence of vehicle vibrations on the throttle body and actuator by enhancing the rigidity with which to support the throttle body and actuator in a simple structure.

A head cover structured and arranged to cover at least part of a face of a cylinder head of an internal combustion engine is described. The head cover includes a chamber formation part structured and arranged to provide a chamber to restrain sound propagating through air from the cylinder head. The chamber formation part includes a partition part for partitioning the chamber from a space on a cylinder head side. The partition part has a convex part projecting into the chamber, and a through hole may be provided in the convex part that penetrates from the space on the cylinder head side to the chamber.