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 control apparatus applied to an internal combustion engine including a spark plug includes an in-cylinder pressure acquisition section, a frequency signal transmitting section which transmits a frequency signal having a predetermined frequency to a switching element, and a weak discharge generating section which causes the frequency signal to be transmitted during an intake stroke and controls the frequency signal such that a weak discharge is generated at the spark plug a plurality of times. The weak discharge generating section controls the frequency signal so as to cause a duty ratio of the switching element to be changed in accordance with the in-cylinder pressure, such that the frequency of generating weak discharges during a time period in which the frequency signal is transmitted becomes higher than a predetermined frequency.

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 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 includes an ignition coil, an ignition plug and ignition control unit. The ignition control unit includes a secondary current adjusting unit that adjusts, in each cycle, an amount of the secondary current after initiating the discharge, a discharge extension detecting unit that detects an amount of extension of the discharge, and a short determination unit that determines whether a discharge-short has occurred. The ignition control unit controls the secondary current control unit such that a first step and a second step are repeatedly executed. The first step decreases the secondary current while keeping the secondary current higher than a predetermined lower current limit, when the extension amount detected by the discharge extension detecting unit is a predetermined extension amount or more. The second step increases the secondary current when the short determination unit determines that a discharge-short has occurred.

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: A spark plug includes a main ground electrode having a main connecting portion connected to the housing and forming a discharge gap between the main ground electrode and the center electrode, and a sub ground electrode having a sub connecting portion connected to the housing. The direction on which the main connecting portion and a plug center axis are arranged is set to be perpendicular to an air flow direction of an air stream in the combustion chamber. The sub connecting portion is located in a downstream side than the main connecting portion. The tip end position of the sub ground electrode in the plug axial direction is located in farther tip end side than that of the main ground electrode is. The sub ground electrode is configured such that an end point of the discharge spark is movable on the sub ground electrode.

Abstract: An ignition device includes an ignition coil, an ignition plug and ignition control unit. The ignition control unit includes a secondary current adjusting unit that adjusts, in each cycle, an amount of the secondary current after initiating the discharge, a discharge extension detecting unit that detects an amount of extension of the discharge, and a short determination unit that determines whether a discharge-short has occurred. The ignition control unit controls the secondary current control unit such that a first step and a second step are repeatedly executed. The first step decreases the secondary current while keeping the secondary current higher than a predetermined lower current limit, when the extension amount detected by the discharge extension detecting unit is a predetermined extension amount or more. The second step increases the secondary current when the short determination unit determines that a discharge-short has occurred.

Abstract: An ignition control apparatus applied to an internal combustion engine including a spark plug includes an in-cylinder pressure acquisition section, a frequency signal transmitting section which transmits a frequency signal having a predetermined frequency to a switching element, and a weak discharge generating section which causes the frequency signal to be transmitted during an intake stroke and controls the frequency signal such that a weak discharge is generated at the spark plug a plurality of times. The weak discharge generating section controls the frequency signal so as to cause a duty ratio of the switching element to be changed in accordance with the in-cylinder pressure, such that the frequency of generating weak discharges during a time period in which the frequency signal is transmitted becomes higher than a predetermined frequency.

Abstract: A spark plug includes a main ground electrode having a main connecting portion connected to the housing and forming a discharge gap between the main ground electrode and the center electrode, and a sub ground electrode having a sub connecting portion connected to the housing. The direction on which the main connecting portion and a plug center axis are arranged is set to be perpendicular to an air flow direction of an air stream in the combustion chamber. The sub connecting portion is located in a downstream side than the main connecting portion. The tip end position of the sub ground electrode in the plug axial direction is located in farther tip end side than that of the main ground electrode is. The sub ground electrode is configured such that an end point of the discharge spark is movable on the sub ground electrode.

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: A spark plug has a housing, a pair of center and ground electrodes configured to define a spark gap therebetween, a guide member and an oblique surface. The ground electrode has a standing portion that stands distalward from a distal end of the housing. The guide member is configured to guide the flow of an air-fuel mixture in a combustion chamber of an engine to the spark gap. The guide member protrudes distalward from the distal end of the housing at a different circumferential position from the ground electrode. The oblique surface is formed at the distal end of the housing so as to be circumferentially positioned between the guide member and the standing portion of the ground electrode. The oblique surface is oblique to the axial direction of the spark plug so that the radial distance between the oblique surface and the center electrode decreases in the distalward direction.

Abstract: A spark plug 1 includes a housing 2, an insulator 3, a center electrode 4 held inside the insulator 3 such that a distal end portion 41 protrudes, a ground electrode 5 including a standing portion 51 and an opposing portion 52, and a guide member 22 that has a guide surface 221 facing the standing portion 51 of the ground electrode 5 and functions to guide a flow of an air-fuel mixture in a combustion chamber of an internal combustion engine to a spark discharge gap G formed between the center electrode 4 and the opposing portion 52 of the ground electrode 5. The opposing portion 52 of the ground electrode 5 has an opposing surface 521 that opposes the center electrode 4, a back surface 522 on the opposite axial side to the opposing surface 521, and a pair of side surfaces 523 and 524 that connect the opposing surface 521 and the back surface 522.

Abstract: A spark plug 1 includes a housing 2, an insulator 3, a center electrode 4 held inside the insulator 3 such that a distal end portion 41 protrudes, a ground electrode 5 including a standing portion 51 and an opposing portion 52, and a guide member 22 that has a guide surface 221 facing the standing portion 51 of the ground electrode 5 and functions to guide a flow of an air-fuel mixture in a combustion chamber of an internal combustion engine to a spark discharge gap G formed between the center electrode 4 and the opposing portion 52 of the ground electrode 5. The opposing portion 52 of the ground electrode 5 has an opposing surface 521 that opposes the center electrode 4, a back surface 522 on the opposite axial side to the opposing surface 521, and a pair of side surfaces 523 and 524 that connect the opposing surface 521 and the back surface 522.

Abstract: A spark plug for an internal combustion engine includes a tubular housing, a tubular insulator, a center electrode, a ground electrode and a guide member. The guide member is configured to guide the flow of an air-fuel mixture in a combustion chamber of the engine to a spark gap formed between the center electrode and the ground electrode. Moreover, in the spark plug, the following dimensional relationships are satisfied: b??67.8×(a/D)+27.4; b??123.7×(a/D)+64.5; ?0.4?(a/D)?0.4; and 0°?b?90°. Further, with an oblique angle ? being in the range of 0 to 30°, the following dimensional relationship is also satisfied: 0.8?r/R?1. Consequently, the spark plug can secure, with a simple configuration, a stable ignition capability regardless of the mounting posture of the spark plug to the engine.

Abstract: A spark plug has a housing, a pair of center and ground electrodes configured to define a spark gap therebetween, a guide member and an oblique surface. The ground electrode has a standing portion that stands distalward from a distal end of the housing. The guide member is configured to guide the flow of an air-fuel mixture in a combustion chamber of an engine to the spark gap. The guide member protrudes distalward from the distal end of the housing at a different circumferential position from the ground electrode. The oblique surface is formed at the distal end of the housing so as to be circumferentially positioned between the guide member and the standing portion of the ground electrode. The oblique surface is oblique to the axial direction of the spark plug so that the radial distance between the oblique surface and the center electrode decreases in the distalward direction.

Abstract: A spark plug for an internal combustion engine includes a tubular housing, a tubular insulator, a center electrode, a ground electrode and a guide member. The guide member is configured to guide the flow of an air-fuel mixture in a combustion chamber of the engine to a spark gap formed between the center electrode and the ground electrode. Moreover, in the spark plug, the following dimensional relationships are satisfied: b??67.8×(a/D)+27.4; b??123.7×(a/D)+64.5; ?0.4?(a/D)?0.4; and 0°?b?90°. Further, with an oblique angle ? being in the range of 0 to 30°, the following dimensional relationship is also satisfied: 0.8?r/R?1. Consequently, the spark plug can secure, with a simple configuration, a stable ignition capability regardless of the mounting posture of the spark plug to the engine.