An ignition system includes a dividing wall which divides a combustion chamber of an engine into a main chamber and a pre-chamber and has formed therein at least one spray hole which communicates between the main chamber and the pre-chamber, and a spark plug in which voltage is applied across a spark gap between a first electrode and a second electrode to create an electrical spark to ignite fuel. The pre-chamber has the first electrode. The dividing wall or a member which electrically conducts with the dividing wall has the second electrode. The ignition system executes an after-top-dead-center ignition control mode to ignite fuel after a compression stroke top dead center. In the after-top-dead-center ignition control mode, an ignition source which is in the form of a self-growable flame kernel is provided in a spray hole-nearby region, the spray hole, or the main chamber within a crank angle of 20° after an ignition timing at which the voltage starts to be applied across the spark gap. The spray hole-nearby region is a region which is located 3 mm or less away from a spray hole center in the pre-chamber.

An engine includes a cylinder block in which a cylinder is formed, a piston arranged to be reciprocally movable in the cylinder, a cylinder head that is arranged on an upper side of the cylinder block and forms a combustion chamber between an inner peripheral surface of the cylinder and an upper surface of the piston, and an ignition plug arranged in the cylinder head. An inner peripheral portion of the cylinder head includes an inner peripheral side portion formed to be flush with the inner peripheral surface of the cylinder, and a tilting portion tilting from the upper surface of the piston to a side surface is formed on the piston.

An engine includes a cylinder block in which a cylinder is formed, a piston arranged to be reciprocally movable in the cylinder, a cylinder head that is arranged on an upper side of the cylinder block and forms a combustion chamber between an inner peripheral surface of the cylinder and an upper surface of the piston, and an ignition plug arranged in the cylinder head. An inner peripheral portion of the cylinder head includes an inner peripheral side portion formed to be flush with the inner peripheral surface of the cylinder, and a tilting portion tilting from the upper surface of the piston to a side surface is formed on the piston.

A piston for use in 4 Cycle reciprocating Internal Combustion Engines. The one embodiment includes a multifunctional Engraving or Imprint that is machined into the crown of the piston. This “Imprint” consists of concentric circles of metal removed in a machining process resulting in the compartments of the functional areas within the crown of the piston connected by either the height and or cross drillings within the Imprint. The functional result is to create low and high pressure zones within the crown of the piston as it proceeds upward on the compression stroke facilitating the creation of an active moving rotational swirl in the outer 25% on the top surface area of the piston circumference. The active swirl pattern results in ultimate homogenization of the air fuel mixture leaving no area of the combustion chamber with weak or separated air and fuel molecules resulting in enhanced power and complete combustion.

A piston for use in 4 Cycle reciprocating Internal Combustion Engines. The one embodiment includes a multifunctional Engraving or Imprint that is machined into the crown of the piston. This “Imprint” consists of concentric circles of metal removed in a machining process resulting in the compartments of the functional areas within the crown of the piston connected by either the height and or cross drillings within the Imprint. The functional result is to create low and high pressure zones within the crown of the piston as it proceeds upward on the compression stroke facilitating the creation of an active moving rotational swirl in the outer 25% on the top surface area of the piston circumference. The active swirl pattern results in ultimate homogenization of the air fuel mixture leaving no area of the combustion chamber with weak or separated air and fuel molecules resulting in enhanced power and complete combustion.

A compression-ignition type internal combustion engine that burns a gaseous fuel, improves an ignition performance not only at a center part of the combustion chamber but also at an outer edge part. The compression-ignition engine comprises an electromagnetic wave generator configured to generate an electromagnetic wave, a controller configured to control the electromagnetic wave generator, and a plasma generator comprising a boosting circuit that constitutes a resonator configured to boost the electromagnetic wave, a first electrode configured to receive an output from the boosting circuit, and a second electrode provided to a vicinity of the first electrode, and the plasma generator is configured such that the first electrode is extruded and exposed toward a combustion chamber of the internal combustion engine, and a plurality of plasma generators are provided.

To effectively suppress strong knock that occurs in the operating region of high load and high rotation in a specific engine having a pre-chamber in a combustion chamber, the engine includes a piston that defines a combustion chamber together with a cylinder block and a cylinder head. The combustion chamber includes a sub-chamber and a main chamber separated from the sub-chamber by a pre-chamber. The specific ratio obtained by dividing a volume of the sub-chamber by a stroke volume of a cylinder is greater than or equal to 0.00005 and less than or equal to 0.00045.

An engine capable of reducing the content of hydrocarbon in exhaust gas is provided. When viewed parallel to cylinder center axes, tangential virtual lines extending from endpoints of curved port central axes along tangent lines of the endpoints pass intake valve ports, straight port central axes extending from the endpoints of the curved port central axes are further away from a partition wall than the tangential virtual lines, and intake air bent through curved ports passes straight ports and is sucked through the intake valve ports along the wall between the cylinders.

An engine capable of reducing the content of hydrocarbon in exhaust gas is provided. When viewed parallel to cylinder center axes, tangential virtual lines extending from endpoints of curved port central axes along tangent lines of the endpoints pass intake valve ports, straight port central axes extending from the endpoints of the curved port central axes are further away from a partition wall than the tangential virtual lines, and intake air bent through curved ports passes straight ports and is sucked through the intake valve ports along the wall between the cylinders.

An ignition device is provided, which can boost an electromagnetic wave supplied by a resonance structure, and cause a discharge by enhancing a potential difference between a discharge electrode and a ground electrode, and even though such a structure of the ignition device, a downsize and a thickness reduction, specifically, the thickness reduction can be achieved. On a main surface of a rectangular insulting substrate (2), an input electrode (3), a coupling electrode (4), a discharge electrode (6), and a ground electrode (7), are provided. The input electrode (3) is connected to an outside terminal on one shorter side. The coupling electrode (4) is capacity-coupled with the input electrode (3). The discharge electrode (6) is connected to the coupling electrode (4) on the other shorter side through a coupling line (5). The ground electrode (7) is, on both longer sides of the main surface of the rectangular insulating substrate (2), capacity-coupled with the coupling electrode (4) and capacity-coupled with the coupling line (5), and extended to the other shorter side. A resonance circuit includes a capacitor constituted by the capacity coupling and an inductor constituted by the coupling line (5). Thereby, the electromagnetic wave supplied from the outside terminal into the input electrode is resonated, a potential difference between the discharge electrode (6) and the ground electrode (7) is enhanced, and then, a discharge is caused.