The present invention relates to a gas intake device (1) for a cylinder of an internal-combustion engine. The gas intake device comprises two intake pipes (5a, 5b), two intake valves (4), two intake valve calibration parts (6a, 6b) and, in each intake pipe (5a, 5b), means for forming an aerodynamic gas motion of tumble type in the cylinder. Furthermore, for each intake pipe (5a, 5b), the intersection between intake pipe (5a, 5b) and calibration part (6a, 6b) occurs along a line non-parallel to the plane of the fire face. Besides, the inclination angle of this intersection is different for each pipe (5a, 5b).

An improved air-cooled aviation engine includes a compact combustion chamber having an intake valve opening, an exhaust valve opening, and a generally elliptical shape. The elliptical shape has a major axis and a minor axis, with the major axis intersecting both the intake valve opening and the exhaust valve opening. In some examples, the major axis is the same length or shorter than a diameter of a cylinder bore of the engine, and the minor axis is smaller than the major axis. Combustion is thus constrained to a smaller area than that of the cylinder bore.

A cylinder head includes an intake-side wall part (1a) that upwardly extends from a cylinder head lower surface (lb) coupled to a cylinder block; a port circumferential wall part (4) that forms therein an intake port (3) communicating with a combustion chamber (2) of an engine; an outer longitudinal rib (14) that projects from an outer surface of the port circumferential wall part (4) on a side of the cylinder head lower surface (lb); and a boss part (13) that is bulged from the intake-side wall part (1a) on one end portion of the outer longitudinal rib (14). The port circumferential wall part (4) includes a resin part disposed along an inner surface thereof. The outer longitudinal rib (14) extends in a direction away from the intake-side wall part (1a) along a flow direction of intake air flowing inside the intake port (3). The boss part (13) includes a hole part (13a) that discharges gas in the intake port (3) when injection molding of the resin part is carried out.

A cylinder head that can efficiently cool air that flows in intake ports of respective cylinders without causing a difference among the cylinders. A cooling water channel is provided in peripheries of the intake ports in the cylinder head. The cooling water channel includes a plurality of water jackets that independently cover parts of respective wall surfaces of a plurality of intake ports. Further, the cooling water channel includes a main channel for cooling water supply that extends in a longitudinal direction of the cylinder head, on an upper part of a row of the intake ports, and the main channel and the respective water jackets are each connected via branch channels for cooling water supply.

Apparatuses, systems and method for utilizing multi-zoned combustion chambers (and/or multiple combustion chambers) for achieving compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in an internal combustion engine are provided. In addition, improved apparatuses, systems and methods for achieving and/or controlling compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in a “Siamese cylinder” internal combustion engine are provided.

An engine with a vertically oriented parallel valve and stem arrangement accommodating tumble flow to support spark-ignited fuel usage. The engine may be provided in a configuration generally suited for swirl flow, compression combustion fuel usage. However, the introduction of a unique, replaceable valve head assembly may be utilized to induce tumble flow within a combustion chamber of the engine. Thus, spark-ignited fuel may be utilized without requiring vast overhaul of the engine to accommodate such fuels. Notably, with the addition of such an assembly, diesel fuel may be replaced with natural gas on large scale equipment without the requirement of impractically burdensome or expensive measures.

An engine includes at least one cylinder, a first intake valve and a second intake valve associated with the cylinder, to control a flow of intake air from a first intake duct and a second intake duct, respectively. The two intake ducts communicate with a common intake manifold, so as to receive air at the same pressure. During the intake stage, in each cylinder operating cycle, initially an opening and closing movement of only the first intake valve is activated, while the second intake valve remains closed and, subsequently, an opening and closing movement of only said second intake valve is activated, while the first intake valve remains closed. In this way, the two air flows at the same pressure entering the cylinder give rise to a high turbulent kinetic energy, to the advantage of combustion efficiency and reduction of harmful exhaust emissions.

A first coolant flow passage is provided to extend in a longitudinal direction of a cylinder head. In at least one of cross sections perpendicular to the longitudinal direction, the first coolant flow passage is located between a flat plane including central axes of a plurality of combustion chambers and parallel to the longitudinal direction and a central line plane including central lines of a plurality of intake ports. In at least one of cross sections perpendicular to the longitudinal direction, at least a portion of a second coolant flow passage is located between the combustion chamber and the first coolant flow passage. A coolant at a temperature lower than that of a coolant flowing in the second coolant flow passage flows in the first coolant flow passage.

The present invention relates to a gas inlet device (1) for a cylinder of an internal combustion engine. The gas inlet device (1) comprises an inlet port (5), an inlet valve (4), a calibration (6) of the inlet valve (4), means for forming a tumble-type aerodynamic movement of the gas in the cylinder, and a mask (10). Furthermore, the intersection (7) between the inlet port (5) and the calibration (6) is along a straight line not parallel to the plane of the firing face (FF). In addition, the mask (10) is oriented in the same way as the end of the inlet port (5).

An intake device of an engine having cylinders is provided. The intake device includes a cylinder head formed with two intake ports per cylinder, and a forced induction system. One of the two intake ports is designed to have a smaller passage cross-sectional area at a throat portion thereof than that of the other intake port, and to cause a strength of a tumble flow strength of intake air formed within a combustion chamber to be stronger when a flow of the intake air into the combustion chamber is assumed to be caused only from the one of the two intake ports, than only from the other intake port. A tumble ratio of the intake air flow within the combustion chamber is a predetermined value or greater when the intake air is forcibly induced and flows into the combustion chamber from the two intake ports.