In a combustion cycle in which fuel for forming a homogenized air-fuel mixture in the combustion chamber is injected from the first fuel injector, ignition-use fuel for forming an ignition-use air-fuel mixture in the vicinity of the electrode part is injected from the second fuel injector, and lean combustion is performed by an excess air rate of 2.0 or more, the ignition-use fuel is injected by at least an injection rate of 1.0 mm.sup.3/ms or more for a duration of 250 μs or more in an interval from a crank angle advanced by exactly 20 degrees from an ignition timing of the spark plug to the ignition timing, and the quantity of the ignition-use fuel is 2.0 mm.sup.3/st or less.

A combustion chamber structure in which an installation hole of the injector is improved to realize a rapid combustion and to reduce an unburned hydrocarbon. In the combustion chamber, a leading end of an injector is withdrawn from an upper end of an opening of an installation hole, and an additionally expanded surface area is formed on an upper inner surface of the installation hole from a portion to which the leading end of the injector is situated. to an opening end of the installation hole. An angle between the additionally expanded surface area and a joint surface of a cylinder head is narrower than an angle between a center axis of the installation hole and the joint surface.

In an internal combustion engine provided with an electro-hydraulic system for variable actuation of the intake valves of the engine, each cylinder has two intake valves, which are associated with two intake conduits and are controlled by a single cam of a camshaft through a single hydraulic circuit. The communication of the hydraulic actuators of the two intake valves with a discharge channel is controlled by two electrically-actuated control valves, both of an on/off two-position type, arranged in series with each other along a hydraulic line for communication between the a pressure volume and the discharge channel.

An engine is provided, which includes a combustion chamber defined by a crown surface of a piston, an inner wall surface of a cylinder in which the piston is slidably accommodated, and a pentroof-type ceiling surface formed in a cylinder head and formed with an intake port and an exhaust port. The crown surface includes an exhaust-side bottom part, an intake-side bottom part, an exhaust-side sloped surface rising toward a center part of the crown surface from the exhaust-side bottom part, an intake-side sloped surface rising toward the center part from the intake-side bottom part, and a flat surface provided continuously between upper ends of the exhaust-side and intake-side sloped surfaces, and extending perpendicularly to a cylinder axial direction in the center part of the crown surface. A surface area of the flat surface is larger than a surface area of the exhaust-side sloped surface.

An assembly structure of a nonmagnetic member to which a position sensor arranged to to sense a rotation position of the rotation member, includes: a nonmagnetic member including a hollow portion; a cover which is fixed to an opening end portion of the hollow portion; and a retaining portion which is provided on an outer circumference portion of the hollow portion of the nonmagnetic member, and to which the position sensor is assembled from the opening end portion's side to be slid in a rotation axis direction, the cover restricting movements of the magnet holding portion and the position sensor in the rotation axis direction in a case where the cover is fixed to the nonmagnetic member in a state where the magnet holding portion and the position sensor are assembled to the nonmagnetic member.

An internal combustion engine for gaseous fuel includes a cylinder and a piston for reciprocal movement in the cylinder along a reciprocal axis, whereby a combustion chamber is at least partially delimited by the cylinder and the piston. The piston includes a piston crown facing the combustion chamber, a piston crown projection of the piston crown in a direction parallel to the reciprocal axis and onto a piston crown plane extending transversally to the reciprocal axis having a piston crown center point, the piston crown comprising a piston bowl surface defining a piston bowl and a piston rim portion enclosing the piston bowl surface. A piston bowl opening is the intersection between the piston rim portion and the piston bowl surface. The piston bowl opening has an opening center of gravity in the piston crown plane. The opening center of gravity is offset from the piston crown center point.

An engine is provided, which includes a combustion chamber defined by a piston crown surface, an inner wall surface of a cylinder, and a pentroof ceiling surface formed in a cylinder head, and an ignition part of a spark plug disposed at the ceiling surface to achieve flame propagation combustion inside the combustion chamber. A cavity recessed in a spherical cap shape is formed in a central area of the crown surface. An opening of an intake port is formed in the ceiling surface (intake side) and an opening of an exhaust port is formed in the ceiling surface (exhaust side). When seen in a cross-sectional view taken along a cylinder axis, the ignition part is located above the cavity to be offset toward the exhaust side with respect to a cylinder axial line whereas a cavity center point is located to be offset toward the intake side.

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.

With regard to an internal combustion engine having a tumble flow formed in a cylinder, an object of the invention is to intensify the tumble flow. There is provided an internal combustion engine having a pent-roof type combustion chamber. In a predetermined area in the vicinity of an opening of an intake port to a combustion chamber, an upper wall surface of the intake port is extended approximately linearly while being inclined to an intake port-side ceiling surface more downward than a normal direction of the intake port-side ceiling surface in a side view. In a partial area in the predetermined area of the intake port, a distance between lateral wall surfaces on a left side and on a right side of the intake port is gradually increased toward downstream in a top view.