A breather chamber structure for an internal combustion engine wherein the breather chamber can be disposed compactly and the degree of freedom in the layout of the parts of the internal combustion engine can be raised. The breather chamber structure includes a crankcase, a cylinder body provided upwardly on the crankcase, and a breather chamber configured to separate oil from oil mist in the crankcase. The breather chamber includes a crankcase side breather chamber provided in the crankcase and open to a joining plane between the crankcase and the cylinder body, and a cylinder side breather chamber provided in the cylinder body and open to the joining plane.

A blow-by gas reduction device includes: a gas return pipe, one end of which is connected to an engine and the other end of which is connected to an intake pipe, to return a blow-by gas in the engine to an intake side; an oil separator that is connected to the gas return pipe; an oil return pipe that is connected to the oil separator and is disposed with an inclination so as to return the oil to an inside of the engine; and a check valve that is provided in the oil return pipe, wherein the oil return pipe between the oil separator and the check valve is formed such that that the oil return pipe located at the check valve side is located at a lower side everywhere as compared with the oil return pipe located at the oil separator side.

An oil separating device for separating an oil mist from a blow-by gas is arranged on a flow passage of the blow-by gas. The oil separating device includes an oil separator having an inlet formed at one end thereof and an outlet formed at another end thereof opposite to the one end; a collision wall arranged at a downstream side of the oil separator, and including an uneven portion formed on a surface thereof to face the outlet of the oil separator; and a filter arranged between the oil separator and collision wall. The oil separator is formed such that the oil mist in the blow-by gas coalesces together to form a coalesced oil mist, the filter removes the coalesced oil mist from the blow-by gas, and the collision wall separates a remained oil mist remained in the blow-by gas through the filter.

A method of removing oil from blowby vapors in an engine having a crankcase and an intake manifold includes filtering the blowby vapor from the engine crankcase to form a vapor depleted of oil and a collected oil. The vapor depleted of oil is communicated to the engine manifold. At high engine loads the collected oil is held in a chamber, and at low engine loads while the engine is still running, the collected oil is forced from the chamber back to the crankcase.

A blow-by gas reduction device includes: a gas return pipe, one end of which is connected to an engine and the other end of which is connected to an intake pipe, to return a blow-by gas in the engine to an intake side; an oil separator that is connected to the gas return pipe; an oil return pipe that is connected to the oil separator and is disposed with an inclination so as to return the oil to an inside of the engine; and a check valve that is provided in the oil return pipe, wherein the oil return pipe between the oil separator and the check valve is formed such that that the oil return pipe located at the check valve side is located at a lower side everywhere as compared with the oil return pipe located at the oil separator side.

An internal combustion engine includes: a cylinder having a combustion chamber formed at an upper side thereof and accommodating a piston to be reciprocally movable; a crankcase provided below the cylinder and accommodates a crankshaft; and a blow-by gas passageway recirculating blow-by gas, which leaks into the crankcase from the combustion chamber, to the combustion chamber through an intake system, in which an inner surface portion of the crankcase is provided with a blow-by gas intake part, and the blow-by gas intake part includes a protruding portion protruding in a direction in which the crankshaft extends, and the intake port opened in the protruding direction is formed at a tip end portion of the protruding portion.

A vehicle may include an internal combustion engine having a crankcase and a supercharging apparatus, and a crankcase ventilation apparatus having at least one oil-separating apparatus including at least one oil separator. An oil return line may communicate separated oil from the crankcase ventilation apparatus to the crankcase. An ejector pump may be driven via a compressed air flow of the supercharging apparatus and may be configured to generate an underpressure for driving a blow-by gas. The crankcase ventilation apparatus may include a pump control valve configured to at least one of regulate and control the compressed air flow through the ejector pump.

An engine ventilation system may include a main blow-by passage formed at a cylinder block for communicating a crankcase with a cylinder head, a main separating passage formed in a head cover, an inflow passage drawing blow-by gas being transferred to the cylinder head through the main blow-by passage into the main separating passage, a sub-separator receiving a part of blow-by gas from the crankcase, and functioning to recollect the engine oil being collected to the crankcase, a sub-separating passage formed in the head cover, a sub-blow-by passage communicating the sub-separator with the sub-separating passage to transfer the blow-by gas passing via the sub-separator to the sub-separating passage, a main separator disposed in the head cover to separate and collect the engine oil from the blow-by gas passing through the main separating passage and the sub-separating passage, and a return outlet discharging the blow-by gas to an exterior.

A breather chamber structure for an internal combustion engine wherein the breather chamber can be disposed compactly and the degree of freedom in the layout of the parts of the internal combustion engine can be raised. The breather chamber structure includes a crankcase, a cylinder body provided upwardly on the crankcase, and a breather chamber configured to separate oil from oil mist in the crankcase. The breather chamber includes a crankcase side breather chamber provided in the crankcase and open to a joining plane between the crankcase and the cylinder body, and a cylinder side breather chamber provided in the cylinder body and open to the joining plane.

An engine includes: a cylinder block that has a cylinder included in a combustion chamber; a crankshaft that is placed in the cylinder block; a flywheel that is mounted to one end portion of the crankshaft; and a flywheel housing that is placed on a side of one end face of the cylinder block in a direction of the crankshaft and that houses the flywheel. The flywheel housing has a blow-by gas path through which a blow-by gas passes.