In an internal combustion engine, a breather chamber can be formed without increasing the number of component parts. The internal combustion engine (1) comprises an engine block (30) defining a cylinder (2); a case member (19) fastened to a lower part of the engine block to define a crank chamber (4) jointly with the engine block; and a bearing member (50) fastened to the engine block in the crank chamber to rotatably support a crankshaft; wherein the engine block is provided with a central recess (134) formed in a part thereof to which the bearing member is fastened, a blow-by gas inlet passage (112, 116, 121) communicating the central recess with the crank chamber, and a blow-by gas return passage (122, 118) forming a part of a passage communicating the central recess with an intake device, the central recess and the bearing member jointly defining a central breather chamber.

An internal combustion engine having an engine block, a cylinder head, a crankcase and at least one cylinder includes a crankcase ventilation line connected to at least one intake line. The crankcase ventilation line is arranged at least predominantly within the internal combustion engine, in particular within the engine block and/or within the cylinder head, thereby greatly minimizing or eliminating the potential for release of crankcase gas to the environment.

Various embodiments include a method for diagnosing a crankcase ventilation line of a crankcase ventilation device for an internal combustion engine having a crankcase, an intake tract, and a compressor arranged in the intake tract for compressing the intake air comprising: diverting fresh air from the intake tract via a fresh air supply line; either enabling or inhibiting a flow of fresh air into a free volume of the crankcase depending on a switch position of a shut-off valve in the fresh air supply line; detecting a nitrogen oxide concentration in the crankcase during the process of crankcase ventilation, close to the point of introduction into the intake tract upstream of the compressor using a nitrogen oxide sensor; and evaluating the tightness of the crankcase ventilation line based at least in part on the detected nitrogen oxide concentration.

A cylinder head cover structure of an engine includes a positive crankcase ventilation (PCV) valve releasing blow-by gas from an oil separating chamber to an intake system of the engine. The oil separating chamber is included in an oil separator provided to an interior of a cylinder head cover. In the oil separating chamber, oil mist is separated and removed from the blow-by gas. The PCV valve is located between a portion of a defining wall and an exterior wall of the cylinder head cover, and supported by the defining wall and the exterior wall, the defining wall defining the oil separating chamber and the cam housing, and the exterior wall being spaced apart from the portion of the defining wall. The PCV valve is surrounded by a space communicating with the cam housing.

An internal combustion engine includes on-off valves that configure a closed space by closing an internal space of a breather line, a pump that depressurizes or pressurizes the closed space, a pressure sensor that detects a pressure of the closed space, and an abnormality assessment element that assesses abnormality of the breather line. The abnormality assessment element assesses abnormality of the breather line based on a pressure change of the closed space in a case where the closed space is depressurized or pressurized by the pump.

An abnormality determination apparatus for an internal combustion engine in which an intake passage upstream of a supercharger and a crankcase are connected by a breather line includes: an intake flow rate detection unit that detects an intake flow rate in the intake passage; and an abnormality determination unit that determines abnormality of the breather line. The abnormality determination unit accumulates a time for which a rotation second-order component of a fluctuation waveform of the intake flow rate is equal to or more than a threshold over a predetermined period of time and determines the abnormality of the breather line when the accumulated value is less than a predetermined accumulation threshold.

An abnormality determination device of an internal combustion engine in which a breather line connects an intake-air path positioned upstream from a forced-induction system and a crankcase includes an intake-air flow rate sensor that detects an intake air flow rate in the intake-air path, a pressure sensor that detects a pressure in the breather line, and an abnormality determination unit that determines abnormality of the breather line. The abnormality determination unit compares the pressure and a threshold for each flow rate, integrates a number of times the pressure becomes the threshold or greater, and determines abnormality of the breather line when an integrated value becomes a predetermined value or greater within a predetermined time. The abnormality determination unit calculates a weight coefficient for each flow rate and assigns weights to a number of times the pressure becomes the threshold or greater by using the weight coefficient.

A blow-by gas purge apparatus includes: a positive crankcase ventilation (PCV) valve disposed on a cylinder head; a head passage penetrating on the cylinder head to communicate with a discharge side of the PCV valve; and a port adaptor interposed between the cylinder head and an intake manifold. The port adaptor includes: multiple intake communication holes such that each intake runner of the intake manifold communicates with each intake port of the cylinder head; an inlet hole communicating with the head passage; and a distribution passage dividing and supplying blow-by gases introduced through the inlet hole into the multiple intake communication holes.

An oil and gas separation device for an internal combustion engine includes a first chamber, a second chamber, and a third chamber provided successively from bottom to top, wherein the first chamber is connected to the second chamber through a first gas channel. The second chamber is connected to the third chamber through a second gas channel. The third chamber is connected to a gas outlet pipe. A bottom of the first chamber is connected to an internal combustion engine body. A lower oil baffle plate is provided between the bottom of the first chamber and the internal combustion engine body. The first gas channel is longitudinally covered by the lower oil baffle plate. The oil and gas separation effect and speed can be improved by employing the oil and gas separation device for the internal combustion engine of the present disclosure.

A blow-by gas purge apparatus includes: a positive crankcase ventilation (PCV) valve disposed on a cylinder head; a head passage penetrating on the cylinder head to communicate with a discharge side of the PCV valve; and a port adaptor interposed between the cylinder head and an intake manifold. The port adaptor includes: multiple intake communication holes such that each intake runner of the intake manifold communicates with each intake port of the cylinder head; an inlet hole communicating with the head passage; and a distribution passage dividing and supplying blow-by gases introduced through the inlet hole into the multiple intake communication holes.