Abstract: An ignition control system performs discharge generation control, in which a discharge spark is generated, once or a plurality of times during a single combustion cycle. The ignition control system successively calculates an approximate energy density based on a secondary current and a discharge path length. During a predetermined period after blocking of a primary current is performed during a single combustion cycle, the ignition control system calculates an integrated value by integrating the discharge path length at this time, based on the approximate energy density being greater than a predetermined value. The ignition control system performs the discharge generation control again based on the calculated integrated value being less than a first threshold.

Abstract: A spark plug includes a ground electrode, an insulator, and a center electrode. In a case where a first position of a surface of the ground electrode exposed to a side of an inner wall surface of a cylinder head is a most downstream position in an air flow direction between the center electrode and the ground electrode, and a second position of the inner wall surface of the cylinder head is a position closest to the center electrode on a downstream side of the center electrode in an air flow direction, the spark plug is installed at a position where the first position and the second position are on a same air flow line, or at a position where the first position is recessed to a side where the first position recedes from the inner wall surface than the second position.

Abstract: In an ignition control device for controlling operation of an ignition apparatus, an ignition section has first and second electrodes disposed in a combustion chamber of an internal combustion engine. A voltage application between the first and second electrodes enables a discharge to be generated between the first and second electrodes for igniting a gas mixture in the combustion chamber. A voltage application section performs at least one application of a determination voltage between the first and second electrodes. An occurrence ratio acquisition section acquires a discharge occurrence ratio at the ignition section for the at least one application of the determination voltage. A comparison section compares the discharge occurrence ratio acquired by the occurrence ratio acquisition section with a predetermined determination threshold to thereby determine a degree of wear of at least one of the first and second electrodes.

Abstract: A spark plug includes a ground electrode, an insulator, and a center electrode. In a case where a first position of a surface of the ground electrode exposed to a side of an inner wall surface of a cylinder head is a most downstream position in an air flow direction between the center electrode and the ground electrode, and a second position of the inner wall surface of the cylinder head is a position closest to the center electrode on a downstream side of the center electrode in an air flow direction, the spark plug is installed at a position where the first position and the second position are on a same air flow line, or at a position where the first position is recessed to a side where the first position recedes from the inner wall surface than the second position.

Abstract: An ignition control system performs discharge generation control, in which a discharge spark is generated, once or a plurality of times during a single combustion cycle. The ignition control system successively calculates an approximate energy density based on a secondary current and a discharge path length. During a predetermined period after blocking of a primary current is performed during a single combustion cycle, the ignition control system calculates an integrated value by integrating the discharge path length at this time, based on the approximate energy density being greater than a predetermined value. The ignition control system performs the discharge generation control again based on the calculated integrated value being less than a first threshold.

Abstract: In an ignition control device for controlling operation of an ignition apparatus, an ignition section has first and second electrodes disposed in a combustion chamber of an internal combustion engine. A voltage application between the first and second electrodes enables a discharge to be generated between the first and second electrodes for igniting a gas mixture in the combustion chamber. A voltage application section performs at least one application of a determination voltage between the first and second electrodes. An occurrence ratio acquisition section acquires a discharge occurrence ratio at the ignition section for the at least one application of the determination voltage. A comparison section compares the discharge occurrence ratio acquired by the occurrence ratio acquisition section with a predetermined determination threshold to thereby determine a degree of wear of at least one of the first and second electrodes.

Abstract: In an ignition control system, a primary current control unit performs discharge generation control one or more times during a single combustion cycle. The discharge generation control allows a spark plug to generate a discharge spark. A parameter calculating unit successively calculates a parameter correlated with energy of a discharge spark. An energy density calculating unit successively calculates energy density that is energy per unit length of the discharge spark. When the energy density is greater than a predetermined value during a predetermined period after a primary current is interrupted during a single combustion cycle, an integrated value calculating unit calculates an integrated value by integrating the parameter during the predetermined period. The primary current control unit performs the discharge generation control again when the integrated value calculated by the integrated value calculating unit is less than a predetermined determination threshold.