Abstract: In an ignition apparatus, an ignition plug is provided. In the ignition plug, a tubular outer conductor surrounds an inner conductor, and a dielectric member is disposed in the tubular outer conductor to define a plasma formation region between the inner conductor and the dielectric member. The plasma formation region has opposing first and second ends in the axial direction of the tubular outer conductor, and the first end of the plasma formation region communicates with the combustion chamber. A power source is connected between the inner and tubular outer conductors. A controller causes a power source to apply electromagnetic power pulses with intervals therebetween across the inner and tubular outer conductors during an ignition cycle of an engine. Each of the electromagnetic power pulses forms at least a corresponding plasma in the plasma formation region.

Abstract: An ignition apparatus is provided which ignites a mixture of air and fuel gas by plasma to generate an initial flame. The apparatus includes: a spark plug that includes an inner conductor, a cylindrical outer conductor that holds the inner conductor thereinside, and a dielectric that is provided between the inner conductor and the outer conductor, and that generates plasma in a plasma formation space between the inner conductor and the outer conductor; an electromagnetic wave power supply that generates an electromagnetic wave to apply electromagnetic wave power to the spark plug; an evaluation section that evaluates a state of formation of the plasma; a determination section that determines a matching object of the electromagnetic wave based on an evaluation result by the evaluation section; and a coupled state control section that controls a matching condition of the electromagnetic wave so that the electromagnetic wave matches the matching object.

Abstract: A spark plug includes a housing, an insulator, a center electrode, and an earth electrode. The earth electrode has a gap-forming surface which forms a discharge gap between the gap-forming surface and a tip surface of the center electrode. The insulator includes an insulator protrusion protruding on the tip side of the housing in a plug axial direction. At least one of cross-sections passing through a plug center axis and parallel to the plug axial direction is referred to as an axial parallel cross-section. The outer peripheral surface of the insulator protrusion includes an insulator inclined surface extending inward toward the tip in the plug axial direction, in a straight line or a curve that is convex inward, in the axial parallel cross-section. In the axial parallel cross-section, a virtual straight line passing through both ends of the insulator inclined surface passes through the gap-forming surface.

Abstract: An ignition control system includes a spark plug including a cylindrical ground electrode, a cylindrical insulator having a protruding portion held inside the ground electrode and protruding toward a tip side the spark plug relative to the ground electrode, and a center electrode held inside the insulator and exposed from the insulator, an ignition coil including a primary coil and a secondary coil, and a primary current control unit performing creeping discharge control for generating a creeping discharge along a surface of the insulator, and air discharge transition control for stopping the creeping discharge occurring in the spark plug after the creeping discharge control is performed, and cutting off primary current after a discharge stop period ends, in one combustion cycle of the engine.

Abstract: A spark plug has a tubular ground electrode, an insulator, and a center electrode. The insulator has an insulator protruding portion protruding to a tip end side in a plug axial direction with respect to the ground electrode. The center electrode 4 has an exposed portion exposed through a tip end of the insulator protruding portion. The exposed portion of the center electrode has a first part covering the insulator protruding portion from the tip end side in the plug axial direction, and a second part extending from the first part to a base end side in the plug axial direction and covering the entire circumference of an outer peripheral surface of the insulator protruding portion from an outer peripheral side in a plug radial direction.

Abstract: In a spark plug for an internal combustion engine, a cylindrical insulator is arranged radially inside a cylindrical ground electrode, and includes an insulator protruding portion protruding further toward a distal end side in an axial direction than a distal end of the ground electrode. A center electrode is held radially inside the insulator, and includes an exposed portion exposed from a distal end of the insulator protruding portion. The spark plug generates a discharge from the exposed portion to the ground electrode, in a discharge gap formed along a surface of the insulator protruding portion. At least one of the exposed portion and the insulator protruding portion includes a flow inlet that is open on an outer circumferential surface thereof, a flow outlet that is open toward the discharge gap, and a communication passage communicating between the flow inlet and the flow outlet.

Abstract: A spark plug includes a housing, an insulator, a center electrode, and an earth electrode. The earth electrode has a gap-forming surface which forms a discharge gap between the gap-forming surface and a tip surface of the center electrode. The insulator includes an insulator protrusion protruding on the tip side of the housing in a plug axial direction. At least one of cross-sections passing through a plug center axis and parallel to the plug axial direction is referred to as an axial parallel cross-section. The outer peripheral surface of the insulator protrusion includes an insulator inclined surface extending inward toward the tip in the plug axial direction, in a straight line or a curve that is convex inward, in the axial parallel cross-section. In the axial parallel cross-section, a virtual straight line passing through both ends of the insulator inclined surface passes through the gap-forming surface.

Abstract: In a spark plug for an internal combustion engine, a discharge gap is formed between a central electrode and a ground electrode in an axial direction of the spark plug. An insulator of a cylindrical shape has an axial hole and an insulator front end part. The axial hole is formed in the insulator, into which the central electrode is arranged and supported. The insulator front end part projects further toward a front side of the insulator in the axial direction of the spark plug than a location of an opening part formed at a front end side of the axial hole. The discharge gasp is formed in an auxiliary combustion chamber. The outer peripheral side of the auxiliary combustion chamber is covered with the insulator front end part.

Abstract: A center electrode is held in insulating glass, in which a tip end portion of the center electrode protrudes. A ground electrode has a connection part connected to a housing. The ground electrode forms a spark discharge gap between the center electrode and the ground electrode. The ground electrode has a ground base material that includes the connection part and a ground protrusion part that protrudes from the ground base material toward the center electrode and forms the spark discharge gap between the center electrode and the ground electrode. An angle between a ground discharge surface of the ground protrusion part and a side surface of the ground protrusion part is a right angle or an acute angle. At least a portion of the side surface of the ground protrusion part and at least a portion of a side surface of the ground base material are flush with each other.

Abstract: An ignition device ignites a mixture of air and fuel gas by plasma to generate an initial flame. The ignition device includes a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma. The ignition device includes an electromagnetic wave power supply that generates the electromagnetic wave by inputting the electromagnetic wave power Ps to the spark plug and a power supply control unit that controls the electromagnetic wave power supply. The electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies.

Abstract: A spark plug for an internal combustion engine includes a housing, an insulator, and a center electrode. The center electrode includes an inside electrode portion and an outside electrode portion. The housing includes a ground electrode projecting from a distal end portion of the housing toward the distal end side of the plug at a part in a plug circumferential direction. The outside electrode portion projects along a surface of the insulator tip in a direction away from a boundary with the inside electrode portion and includes a projection, which is capable of causing an electrical discharge between the ground electrode and the outside electrode portion. The projection is formed in a region in the plug circumferential direction. The projection and the ground electrode are located at positions different from each other in the plug circumferential direction.

Abstract: A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and a plug cover. The housing has a cylindrical shape. The insulator is held on an inner side of the housing. The insulator has a cylindrical shape. The center electrode is held on an inner side of the insulator. The ground electrode forms a discharge gap with the center electrode. The plug cover, together with the housing, configures an auxiliary combustion chamber in which the discharge gap is arranged. The plug cover includes a spray hole that communicates between the inside and outside of the plug cover. The ground electrode is connected to a plurality of locations on an auxiliary-chamber inner wall surface that includes surfaces of the housing and the plug cover that are exposed to the auxiliary combustion chamber.

Abstract: A spark plug for an internal combustion engine includes a housing, an insulator, and a center electrode. The center electrode includes an inside electrode portion and an outside electrode portion. The housing includes a ground electrode projecting from a distal end portion of the housing toward the distal end side of the plug at a part in a plug circumferential direction. The outside electrode portion projects along a surface of the insulator tip in a direction away from a boundary with the inside electrode portion and includes a projection, which is capable of causing an electrical discharge between the ground electrode and the outside electrode portion. The projection is formed in a region in the plug circumferential direction. The projection and the ground electrode are located at positions different from each other in the plug circumferential direction.

Abstract: In a spark plug for an internal combustion engine, a discharge gap is formed between a central electrode and a ground electrode in an axial direction of the spark plug. An insulator of a cylindrical shape has an axial hole and an insulator front end part. The axial hole is formed in the insulator, into which the central electrode is arranged and supported. The insulator front end part projects further toward a front side of the insulator in the axial direction of the spark plug than a location of an opening part formed at a front end side of the axial hole. The discharge gasp is formed in an auxiliary combustion chamber. The outer peripheral side of the auxiliary combustion chamber is covered with the insulator front end part.

Abstract: In a spark plug, a discharge gap is formed between a ground electrode and a central electrode. The ground electrode has a rod-shaped part and an opposing part. The opposing part faces the central electrode, and has a flat surface part and a slope surface part. The slope surface part is formed on a part of the opposing part in an extending direction of the ground electrode, and formed on the opposing part and gradually separated from the central electrode along a width direction of the opposing part. The spark plug has a ratio V/W within a range of 0.5<V/W<2.0. V indicates a length of the opposing part measured in a gap formation direction in which the central electrode, the discharge gap and the opposing part are arranged in order. W indicates a length of the opposing part in the ground electrode width direction.

Abstract: An ignition device ignites a mixture of air and fuel gas by plasma to generate an initial flame. The ignition device includes a spark plug having an inner conductor, a cylindrical outer conductor that holds the inner conductor inside, and a dielectric provided between the inner conductor and the outer conductor, and the spark plug configured to emit an electromagnetic wave to a plasma formation space between the inner conductor and the outer conductor to generate a plasma. The ignition device includes an electromagnetic wave power supply that generates the electromagnetic wave by inputting the electromagnetic wave power Ps to the spark plug and a power supply control unit that controls the electromagnetic wave power supply. The electromagnetic wave power supply is configured to generate high frequency power at a number of different frequencies.

Abstract: In a spark plug for an internal combustion engine, a cylindrical insulator is arranged radially inside a cylindrical ground electrode, and includes an insulator protruding portion protruding further toward a distal end side in an axial direction than a distal end of the ground electrode. A center electrode is held radially inside the insulator, and includes an exposed portion exposed from a distal end of the insulator protruding portion. The spark plug generates a discharge from the exposed portion to the ground electrode, in a discharge gap formed along a surface of the insulator protruding portion. At least one of the exposed portion and the insulator protruding portion includes a flow inlet that is open on an outer circumferential surface thereof, a flow outlet that is open toward the discharge gap, and a communication passage communicating between the flow inlet and the flow outlet.

Abstract: An ignition apparatus for an internal combustion engine provided with an ignition coil and a spark plug. An ECU enables operation of a plurality of continuous discharges in the spark plug and also detects a flow speed of a combustible air/fuel mixture. In a first discharge, a supply of a primary current terminates the first discharge, with energy remaining in the ignition coil, from an initiation of the ignition to an initiation of the spark plug, when the detected flow speed exceeds a predetermined first threshold. Thereafter, a second discharge is performed by shutting off the primary current.

Abstract: A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and a plug cover. The housing has a cylindrical shape. The insulator is held on an inner side of the housing. The insulator has a cylindrical shape. The center electrode is held on an inner side of the insulator. The ground electrode forms a discharge gap with the center electrode. The plug cover, together with the housing, configures an auxiliary combustion chamber in which the discharge gap is arranged. The plug cover includes a spray hole that communicates between the inside and outside of the plug cover. The ground electrode is connected to a plurality of locations on an auxiliary-chamber inner wall surface that includes surfaces of the housing and the plug cover that are exposed to the auxiliary combustion chamber.

Abstract: A center electrode is held in insulating glass, in which a tip end portion of the center electrode protrudes. A ground electrode has a connection part connected to a housing. The ground electrode forms a spark discharge gap between the center electrode and the ground electrode. The ground electrode has a ground base material that includes the connection part and a ground protrusion part that protrudes from the ground base material toward the center electrode and forms the spark discharge gap between the center electrode and the ground electrode. An angle between a ground discharge surface of the ground protrusion part and a side surface of the ground protrusion part is a right angle or an acute angle. At least a portion of the side surface of the ground protrusion part and at least a portion of a side surface of the ground base material are flush with each other.