The disclosure concerns air cleaners. Preferred air cleaners are shown which include a housing and a removable and replacement primary filter cartridge. Optional and advantageous features are shown. The preferred primary filter cartridge is conical in shape. A preferred optional safety or secondary filter cartridge is shown. Preferred methods of assembly and use are provided.

An internal combustion engine includes: an engine main body demarcating a breather chamber that is partitioned from a crank chamber, disposed above the crank chamber, and has an inlet opening opened toward the crank chamber; a multistage transmission housed in the crank chamber and having speed change gear trains that are respectively supported by a pair of transmission shafts and mesh with each other; and a breather passage disposed above the transmission shafts and extending in an up-down direction from the crank chamber to the inlet opening of the breather chamber, the inlet opening being disposed above a half in a height direction of the breather chamber. Accordingly, the internal combustion engine can suppress the entry of splashed oil into the breather chamber more than ever before.

A method for ventilating a crankcase of an internal combustion engine using natural gas as a fuel source may include filtering ambient air through an air filter. The method may also include heating the filtered ambient air by a jacket heat exchanger. The method may further include directing the heated ambient air through an inlet of the crankcase to purge blow-by gases including natural gas from the crankcase.

The disclosure concerns air cleaners. Preferred air cleaners are shown which include a housing and a removable and replacement primary filter cartridge. Optional and advantageous features are shown. The preferred primary filter cartridge is conical in shape. A preferred optional safety or secondary filter cartridge is shown. Preferred methods of assembly and use are provided.

A method for ventilating a crankcase of an internal combustion engine using natural gas as a fuel source may include filtering ambient air through an air filter. The method may also include heating the filtered ambient air by a jacket heat exchanger. The method may further include directing the heated ambient air through an inlet of the crankcase to purge blow-by gases including natural gas from the crankcase.

A breather canister for a crankcase of an engine is provided. The breather canister may comprise: an outer housing and a diffuser. The outer housing may comprise a wall and a floor that cooperate to define an interior chamber, the outer housing comprising an inlet coupled to the floor and defining a first passageway. The diffuser may comprise a stem defining a second passageway, the stem being coupled with the inlet such that the passageway of the inlet and the passageway of the stem are in fluid communication with each other. The wall of the outer housing may define a vent aperture that is in fluid communication with the interior chamber. The diffuser may define an upper aperture and a lower aperture that are each in fluid communication with the passageway of the stem and the interior chamber.

The disclosure concerns air cleaners. Preferred air cleaners are shown which include a housing and a removable and replacement primary filter cartridge. Optional and advantageous features are shown. The preferred primary filter cartridge is conical in shape. A preferred optional safety or secondary filter cartridge is shown. Preferred methods of assembly and use are provided.

An engine breather filter assembly for monitoring an internal combustion comprises: a filter cavity configured to accommodate a breather filter element; a processor; and a sensor module configured to sense a characteristic of the internal combustion engine and output data representative of the sensed characteristic to the processor. The engine breather filter assembly is configured to provide a housing for the processor. The processor is configured to determine a value representative of the firing frequency of the internal combustion engine based on the output data.

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.

An internal combustion engine includes: an engine main body demarcating a breather chamber that is partitioned from a crank chamber, disposed above the crank chamber, and has an inlet opening opened toward the crank chamber; a multistage transmission housed in the crank chamber and having speed change gear trains that are respectively supported by a pair of transmission shafts and mesh with each other; and a breather passage disposed above the transmission shafts and extending in an up-down direction from the crank chamber to the inlet opening of the breather chamber, the inlet opening being disposed above a half in a height direction of the breather chamber. Accordingly, the internal combustion engine can suppress the entry of splashed oil into the breather chamber more than ever before.