A positive crankcase ventilation system includes a positive crankcase ventilation valve, a coupling part, and a plate member. The coupling part is configured to couple the positive crankcase ventilation valve and an internal combustion engine. The plate member is attached to the coupling part on an opposite side from a side where the coupling part and the internal combustion engine contact each other. A portion of the plate member is bent in a direction toward a base of a hose insertion port provided on the positive crankcase ventilation valve, and another portion of the plate member is bent in a direction toward a side wall of an attachment portion of the positive crankcase ventilation valve provided on the coupling part.

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.

The oil mist separator separates oil from blow-by gas which flows through a gas flow passage. A chamber, which is partitioned from the gas flow passage including a gas introduction port, is provided between a cylinder head cover and a baffle plate. A first guide wall, which extends with a downward inclination toward the chamber so as to cover the gas introduction port and the chamber, is provided above the gas introduction port and the chamber. A drain hole for discharging the oil within the chamber is formed in the baffle plate.

An engine housing component is provided, the housing component defining two or more drain channels configured to receive oil separated from a crankcase ventilation system and to drain said oil through the housing component, wherein the engine housing component comprises two or more drain features, each of the drain features corresponding to one of the drain channels, wherein each of the drain features is configured to allow an oil drain pipe to be coupled to the drain feature such that the oil drain pipe is in fluid communication with the corresponding drain channel, wherein a first drain feature differs from the or each of the other drain features, such that a particular oil drain pipe configured to couple to the first drain feature is not couplable to the other drain features. An engine housing assembly and kit of oil drain pipes is also provided.

A breather device for an engine which prevents a blow-by gas outlet passage from being blocked due to freezing, is provided, which includes a valve holder in a cylinder head cover and a breather valve supported by the holder. The holder includes a holder body having a valve port of the breather valve, a metal outlet passage pipe having a blow-by gas outlet passage formed inside, the blow-by gas outlet passage communicating with the valve port and being located below the valve port, and a heater that heats the outlet passage pipe. An outer peripheral surface of the outlet passage pipe is wrapped with the holder body formed of a material having lower thermal conductivity than that of the outlet passage pipe. The holder body has a heater insertion port, and the heater is inserted from the heater insertion port toward a heat input wall of the outlet passage pipe.

An engine is provided where oil is minimally blown off through a breather chamber. The breather chamber includes a plurality of breather inlet chambers each having a breather inlet which opens on a bottom wall; an oil separation chamber where blow-by gases flown out from the breather inlet chambers merge together and oil separation is performed; and a breather outlet. A ceiling wall of each breather inlet chamber is lower than a ceiling wall of an oil separation chamber. It is preferable that the respective breather inlet chambers each have: a remote-side chamber portion disposed remote from the oil separation chamber and a near-side chamber portion disposed near to the oil separation chamber. A ceiling wall of the near-side chamber portion is disposed lower than a ceiling wall of the remote-side chamber portion with a stepped portion formed between the ceiling wall and the ceiling wall.

There is provided a breather chamber structure. An inner wall partitions a breather space surrounded by outer walls into a plurality of chambers including a first chamber, a second chamber, and a third chamber. An inlet allows the gas to flow into the first chamber. A first communication path communicates between the first chamber and the second chamber. A second communication path communicates between the second chamber and the third chamber. An outlet allows the gas in the third chamber to flow out of the breather space. An oil discharge port is configured to return oil separated from gas in the breather space to an oil reservoir. The third chamber has a volume equal to or greater than half of a volume of the breather space. The first chamber has a volume larger than a volume of any of the chambers except for the first and third chambers.

A cylinder head cover that prevents the gas outlet for the blow-by gas from being cooled by structural improvements so that the gas outlet does not freeze or become clogged in a cold condition. A cylinder head cover includes: a gas passage through which blow-by gas from a crankcase passes; and a gas outlet portion protruding upward from a head cover upper wall. The gas outlet portion includes a protruding case portion bulging upward from the head cover upper wall so as to form an outlet passage through which blow-by gas passes, and an air layer is formed outside the outlet passage in the protruding case portion.

A pressure-limiting valve for use in a gas line conveying a gas that includes aerosols. The pressure-limiting valve has a movable valve body, a valve seat, and a compressible coalescing medium placed therebetween. The valve body has passages and nozzle openings and the valve seat has through-holes. In the closed position, the valve functions in separator mode and in the fully open position, in impactor mode. The pressure-limiting valve according to the invention provides a more sensitive response to varying flow conditions, due to deviating surface profiles of the valve seat and coalescing medium, which provide intermediate stages of separator and impactor modes as a function of the volume of flow.

The invention describes an internal combustion engine having at least one crankcase, at least one cylinder head, at least one cylinder head cover, at least one oil separator and at least one oil pan for collecting returning oil as well as having at least one oil return channel that connects the oil separator and the oil pan.