Abstract: A spark plug includes a housing, a porcelain insulator, a center electrode, a ground electrode, and a prechamber-defining portion. The prechamber-defining portion has a prechamber formed therein. The prechamber-defining portion has a plurality of spray holes. At least one of the spray holes is an upstream spray hole which is arranged upstream of a plug center axis in a gas flow within a main combustion chamber and designed such that and an angle which an extension in an opening direction makes with an inner wall surface of the prechamber is selected to be larger than 90°. A spark gap is formed upstream of a plug center axis in the gas flow within the main combustion chamber.

Abstract: A spark plug includes a housing, a porcelain insulator, a center electrode, a ground electrode, and a prechamber-defining portion. The prechamber-defining portion has a prechamber formed therein. The prechamber-defining portion has a plurality of spray holes. At least one of the spray holes is an upstream spray hole which is arranged upstream of a plug center axis in a gas flow within a main combustion chamber and designed such that and an angle which an extension in an opening direction makes with an inner wall surface of the prechamber is selected to be larger than 90°. A spark gap is formed upstream of a plug center axis in the gas flow within the main combustion chamber.

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: An ignition device for an internal combustion engine is provided which includes a spark plug and a controller. The spark plug has a housing with a head protruding into a combustion chamber of the engine. The head has at least a portion located downstream of a spark gap of the spark plug in an air-fuel mixture flow within the combustion chamber. The controller works to perform a plurality of discharge events in the spark plug in each cycle of an operation of the engine. This improves the ability of the spark plug to ignite the mixture without need to increase an ignition energy.

Abstract: An ignition apparatus performs energy input control in which energy is continuously inputted to an ignition coil to enable a spark discharge in a predetermined energy input period after interrupting a primary current by an ignition switch and generating a discharge of a spark plug by a secondary current. A combustion state determination circuit determines a combustion state by comparing a combustion pressure P detected by a combustion state detector. When the combustion pressure P is smaller than a second threshold Pth2, and there is room for improving the combustion state with respect to the present energy input condition, the energy input period IGW is increased or a target secondary current I2* is increased. By compensating the condition of the energy input control in accordance with the combustion state, a target combustion state can be achieved with just enough energy consumption.

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: An ignition apparatus inputs energy during a predetermined energy input period after the interruption of a primary electric current by an ignition switch and a discharge of an ignition plug caused by a secondary electric current. Moreover, the ignition apparatus includes a blow-off detection unit that detects, during the energy input period IGW after the start of the discharge by the ignition plug, occurrence of blow-off of the discharge. When the secondary electric current I2 drops below a blow-off detection electric current threshold value Ibo at a time instant tbo in a “second region” where it is impossible to perform a re-discharge after blow-off, the blow-off detection unit determines that blow-off has occurred and the ignition apparatus stops the energy input from an energy input unit to an ignition coil. By preventing unnecessary energy input, it is possible to suppress unnecessary electric power consumption and wear of electrodes of the ignition plug.

Abstract: An ignition device for an internal combustion engine is provided which includes a spark plug and a controller. The spark plug has a housing with a head protruding into a combustion chamber of the engine. The head has at least a portion located downstream of a spark gap of the spark plug in an air-fuel mixture flow within the combustion chamber. The controller works to perform a plurality of discharge events in the spark plug in each cycle of an operation of the engine. This improves the ability of the spark plug to ignite the mixture without need to increase an ignition energy.

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: An ignition control system is applied to an internal combustion engine having an ignition coil, a switching element and a measurement detection part which detects at least one of a primary and a secondary voltages and a secondary current. The ignition coil has a primary coil and a secondary coil. The switching element performs conduction and interruption the primary current to the primary coil. The ignition control system has a primary current control unit generating a spark discharge at the ignition plug by passing the primary current through the primary coil, and perform interruption of the primary current, and a discharge short-circuiting determination part determining a generation of discharge short-circuiting based on a measured value. The primary current control unit generates the spark discharge again when discharge short-circuiting occurs.

Abstract: In an ignition coil for an internal combustion engine, a spark plug is incorporated which has an insulator including an insulator head that has no corrugation. The ignition coil has a coil body part generating high voltage and a joint part, which holds therein a conducting member electrically connecting the coil body part and a spark plug. The joint part has a plug cap into which the insulator head of the spark plug is inserted and which is formed of an elastic member having a cylindrical shape. The plug cap has a close-contact part whose inner peripheral surface is closely brought into contact with an outer peripheral surface of the insulator. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position.

Abstract: An ignition apparatus includes a spark plug and an ignition coil. The spark plug has a plug terminal protruding proximalward from an insulator. The ignition coil includes a coil main body, which includes a primary coil and a secondary coil, and a helical spring that electrically connects the secondary coil and the plug terminal. The plug terminal is made of a material that is both electrically conductive and magnetic. The plug terminal includes a terminal main body, which has an outer diameter greater than an inner diameter of the spring, and a terminal extension portion that has an outer diameter less than the inner diameter of the spring and extends proximalward from the terminal main body. A distal end portion of the spring abuts the terminal main body. The terminal extension portion is inserted and arranged in the spring. Between an outer circumferential surface of the terminal extension portion and an inner circumferential surface of the spring, there is interposed an insulating member.

Abstract: An ignition apparatus includes an ignition plug, a boost transformer, an ignition power source and a measurement unit. The ignition plug has a center electrode and a ground electrode. The boost transformer supplies the ignition plug with electric power generated in a secondary coil upon supply of AC power from the ignition power source to a primary coil. The measurement unit measures the discharge voltage of the ignition plug. The ignition power source includes a discharge state determining unit that determines the discharge state of the ignition plug based on the measured discharge voltage and a current controlling unit that controls electric current supplied to the primary coil. When a discharge path formed between the center and ground electrodes of the ignition plug is determined by the discharge state determining unit as being in an over-extended state, the current controlling unit reduces the electric current supplied to the primary coil.

Abstract: In a control apparatus, a discharge control unit controls an igniter unit so that a flow of current from a primary coil towards a ground side is blocked, thereby generating a high voltage in a secondary coil, and controls a spark plug so that the spark plug generates electric discharge. An energy input control unit controls an energy input unit so as to input electrical energy to an ignition coil after the start of control of the spark plug by the discharge control unit. A control unit and an abnormality detecting unit detects an abnormality in the igniter unit or the ignition coil based on a first threshold and a first current value that is a value corresponding to a current detected by a current detection circuit at this time, when a first predetermined period elapses after the start of control of the spark plug by the discharge control unit.

Abstract: An ignition apparatus includes a spark plug and an ignition coil. The spark plug has a plug terminal protruding proximalward from an insulator. The ignition coil includes a coil main body, which includes a primary coil and a secondary coil, and a helical spring that electrically connects the secondary coil and the plug terminal. The plug terminal is made of a material that is both electrically conductive and magnetic. The plug terminal includes a terminal main body, which has an outer diameter greater than an inner diameter of the spring, and a terminal extension portion that has an outer diameter less than the inner diameter of the spring and extends proximalward from the terminal main body. A distal end portion of the spring abuts the terminal main body. The terminal extension portion is inserted and arranged in the spring. Between an outer circumferential surface of the terminal extension portion and an inner circumferential surface of the spring, there is interposed an insulating member.

Abstract: An ignition apparatus inputs energy during a predetermined energy input period after the interruption of a primary electric current by an ignition switch and a discharge of an ignition plug caused by a secondary electric current. Moreover, the ignition apparatus includes a blow-off detection unit that detects, during the energy input period IGW after the start of the discharge by the ignition plug, occurrence of blow-off of the discharge. When the secondary electric current I2 drops below a blow-off detection electric current threshold value Ibo at a time instant tbo in a “second region” where it is impossible to perform a re-discharge after blow-off, the blow-off detection unit determines that blow-off has occurred and the ignition apparatus stops the energy input from an energy input unit to an ignition coil. By preventing unnecessary energy input, it is possible to suppress unnecessary electric power consumption and wear of electrodes of the ignition plug.

Abstract: An ignition device includes a spark plug, a measurement value detector, an electrical breakdown determiner, an AC voltage applying section, and a first changing section. The measurement value detector includes primary and secondary coils, and detects at least one measurement value among an ignition coil, a primary current, a primary voltage, a secondary current, and a secondary voltage. The electrical breakdown determiner determines whether a discharge has become an electrical breakdown state based on the measurement value. The AC voltage applying section applies an AC voltage of a first predetermined frequency that causes voltage resonance to the primary coil. The first changing section changes the frequency of the AC voltage to a second predetermined frequency that can maintain the electrical breakdown state and is lower in frequency than the first predetermined frequency when it is determined that the discharge has become the electrical breakdown state.

Abstract: In an ignition coil for an internal combustion engine, a spark plug is incorporated which has an insulator including an insulator head that has no corrugation. The ignition coil has a coil body part generating high voltage and a joint part, which holds therein a conducting member electrically connecting the coil body part and a spark plug. The joint part has a plug cap into which the insulator head of the spark plug is inserted and which is formed of an elastic member having a cylindrical shape. The plug cap has a close-contact part whose inner peripheral surface is closely brought into contact with an outer peripheral surface of the insulator. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position.

Abstract: An ignition apparatus inputs energy during a predetermined energy input period after the interruption of a primary electric current by an ignition switch and a discharge of an ignition plug caused by a secondary electric current. Moreover, the ignition apparatus includes a blow-off detection unit that detects, during the energy input period IGW after the start of the discharge by the ignition plug, occurrence of blow-off of the discharge. When the secondary electric current I2 drops below a blow-off detection electric current threshold value Ibo at a time instant tbo in a “second region” where it is impossible to perform a re-discharge after blow-off, the blow-off detection unit determines that blow-off has occurred and the ignition apparatus stops the energy input from an energy input unit to an ignition coil. By preventing unnecessary energy input, it is possible to suppress unnecessary electric power consumption and wear of electrodes of the ignition plug.

Abstract: An ignition apparatus includes an ignition plug, a boost transformer, an ignition power source and a measurement unit. The ignition plug has a center electrode and a ground electrode. The boost transformer supplies the ignition plug with electric power generated in a secondary coil upon supply of AC power from the ignition power source to a primary coil. The measurement unit measures the discharge voltage of the ignition plug. The ignition power source includes a discharge state determining unit that determines the discharge state of the ignition plug based on the measured discharge voltage and a current controlling unit that controls electric current supplied to the primary coil. When a discharge path formed between the center and ground electrodes of the ignition plug is determined by the discharge state determining unit as being in an over-extended state, the current controlling unit reduces the electric current supplied to the primary coil.