Abstract: An ignition system has an ignition plug and an ignition control unit that controls the ignition plug. When an engine is in a predetermined operating state, the ignition control unit performs ignition control after top dead center to perform ignition after the compression top dead center. The ignition system has an airflow support structure that facilitates the flow of airflow through a discharge gap at least after the compression top dead center. The ignition system is configured such that due to the airflow support structure and the timing of the ignition, airflow at a flow rate of 5 m/s or more flows through the discharge gap during a spark period after top dead center, which is the generation period of the discharge spark in the ignition control after top dead center.

Abstract: 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.

Abstract: An ignition system has an ignition plug and an ignition control unit that controls the ignition plug. When an engine is in a predetermined operating state, the ignition control unit performs ignition control after top dead center to perform ignition after the compression top dead center. The ignition system has an airflow support structure that facilitates the flow of airflow through a discharge gap at least after the compression top dead center. The ignition system is configured such that due to the airflow support structure and the timing of the ignition, airflow at a flow rate of 5 m/s or more flows through the discharge gap during a spark period after top dead center, which is the generation period of the discharge spark in the ignition control after top dead center.

Abstract: A spark plug for an internal combustion engine is provided which is equipped with a tip protrusion disposed on a top of a hollow cylindrical housing of the spark plug. The spark plug also includes a center electrode retained in a porcelain insulator disposed inside the housing and a ground electrode is joined to the housing so as to form a spark gap. The tip protrusion serves to direct a flow of gas to be ignited by a spark produced in the spark gap and is shaped to have a radial width extending in a radial direction of the housing and a circumferential width extending in a circumferential direction of the cylindrical housing. The radial width is greater than the circumferential width. This enhances the efficiency in guiding the flow of gas toward the spark gap.

Abstract: A spark plug for an internal combustion engine is provided which is equipped with a tip protrusion disposed on a top of a hollow cylindrical housing of the spark plug. The spark plug also includes a center electrode retained in a porcelain insulator disposed inside the housing and a ground electrode is joined to the housing so as to form a spark gap. The tip protrusion serves to direct a flow of gas to be ignited by a spark produced in the spark gap and is shaped to have a radial width extending in a radial direction of the housing and a circumferential width extending in a circumferential direction of the cylindrical housing. The radial width is greater than the circumferential width. This enhances the efficiency in guiding the flow of gas toward the spark gap.

Abstract: A protective sleeve for a spark plug includes a center electrode, an insulator, an attachment fitment having an attachment screw section formed on an outer peripheral surface thereof, and a ground electrode. A protective sleeve is disposed in a detachable manner on the outer periphery of the attachment screw section. The attachment fitment includes a flange section that has a diameter larger than that of the attachment screw section on a base end side of the attachment screw section. The protective sleeve includes a main body cylinder section having an inner diameter that is the diameter of the attachment screw section or larger, and smaller than the diameter of the flange section, a large diameter cylinder section having an inner diameter that is the diameter of the flange section or larger, and a step section formed between the large diameter cylinder section and the main body cylinder section.

Abstract: A high-strength ignition coil that can reduce stress produced in a coil case and prevent a casting material from being cracked when the ignition coil is mounted on an engine block. A coil case has a mounting flange on an outer surface thereof. A coil assembly is housed in the coil case. A casting material is filled into a gap between the coil case and the coil assembly and gaps which the coil assembly has. A plurality of first guide ribs are provided on an inner wall surface of the coil case or an outer surface of the coil assembly, for positioning the outer surface of the coil assembly with respect to the inner wall surface of the coil case. A limited area in which there is no first guide rib is provided on the inner wall surface of the coil case which faces the mounting flange, or the outer surface of the coil assembly which faces the mounting flange via the inner wall surface of the coil case.

Abstract: An ignition coil is equipped with a sparkplug of an engine. The ignition coil includes a coil portion, a tower portion, and a plug cap. The coil portion includes a coil case accommodating a primary and secondary coils being coaxial with each other. The coil portion has an end connected with the plug cap via the tower portion. The plug cap is press-fitted with the sparkplug. The coil case has an outer periphery from which a flange portion projects radially outward in a flange-projecting direction. The tower cylinder portion has a tower axis substantially in parallel with a coil axis of the primary and secondary coils. The tower axis is offset from the coil axis in a tower-offset direction. The tower-offset direction is substantially the same as the flange-projecting direction.

Abstract: A high-strength ignition coil that can prevent distortion arising from pin marks formed on a surface of a core and makes it less likely for insulating resin to be cracked. The coil assembly is housed in a coil case. A casting material is filled into a gap between the coil case and the coil assembly and gaps which the coil assembly has. The coil assembly is comprised of a coil pair including a cylindrical primary coil and a secondary coil disposed concentrically with the primary coil, and a core. The core is fitted into a central space of the coil pair and forms a magnetic path. The core is coated with mold resin. Concave portions of pin marks formed on a mold resin coating by removal of core fixing pins when the mold resin coating is formed are filled with mold resin.

Abstract: An ignition coil is equipped with a sparkplug of an engine. The ignition coil includes a coil portion, a tower portion, and a plug cap. The coil portion includes a coil case accommodating a primary and secondary coils being coaxial with each other. The coil portion has an end connected with the plug cap via the tower portion. The plug cap is press-fitted with the sparkplug. The coil case has an outer periphery from which a flange portion projects radially outward in a flange-projecting direction. The tower cylinder portion has a tower axis substantially in parallel with a coil axis of the primary and secondary coils. The tower axis is offset from the coil axis in a tower-offset direction. The tower-offset direction is substantially the same as the flange-projecting direction.

Abstract: A high-strength ignition coil that can reduce stress produced in a coil case and prevent a casting material from being cracked when the ignition coil is mounted on an engine block. A coil case has a mounting flange on an outer surface thereof. A coil assembly is housed in the coil case. A casting material is filled into a gap between the coil case and the coil assembly and gaps which the coil assembly has. A plurality of first guide ribs are provided on an inner wall surface of the coil case or an outer surface of the coil assembly, for positioning the outer surface of the coil assembly with respect to the inner wall surface of the coil case. A limited area in which there is no first guide rib is provided on the inner wall surface of the coil case which faces the mounting flange, or the outer surface of the coil assembly which faces the mounting flange via the inner wall surface of the coil case.

Abstract: A high-strength ignition coil that can prevent distortion arising from pin marks formed on a surface of a core and makes it less likely for insulating resin to be cracked. The coil assembly is housed in a coil case. A casting material is filled into a gap between the coil case and the coil assembly and gaps which the coil assembly has. The coil assembly is comprised of a coil pair including a cylindrical primary coil and a secondary coil disposed concentrically with the primary coil, and a core. The core is fitted into a central space of the coil pair and forms a magnetic path. The core is coated with mold resin. Concave portions of pin marks formed on a mold resin coating by removal of core fixing pins when the mold resin coating is formed are filled with mold resin.

Abstract: An ignition device for an internal combustion engine has a spark plug, an ignition coil, a housing and a mounting portion. The spark plug is for discharging a current to ignite an air-fuel mixture in a combustion chamber of the internal combustion engine. The ignition coil is for supplying the current to the spark plug. The housing encloses the spark plug and the ignition coil therein. The housing has a mounting portion to be disposed in a mounting hole provided in a cylinder head of the internal combustion engine. The mounting portion includes a screw portion a non-screw portion. The screw portion is to be screw-fastened to the mounting hole. The non-screw portion is not to be screw-fastened to the mounting hole.

Abstract: An ignition device for an internal combustion engine has a primary and secondary coils of an ignition coil, a center and ground electrodes of a spark plug, a cylinder shaped insulator and a cylinder shaped tube. The center electrode is disposed apart from the secondary coil in a longitudinal direction of the ignition device. The insulator is made of an insulating material and has a coil surrounding portion surrounding the secondary coil and a plug surrounding portion surrounding the center electrode. The primary coil is wound on an outer circumferential face of the coil surrounding portion. The ground electrode is disposed on an outer circumferential face of the plug surrounding portion. The tube is made of a magnetic material and has a coil covering portion covering the primary coil and a plug covering portion covering the plug surrounding portion and the ground electrode.

Abstract: An internal combustion engine ignition device has a resin layer in a clearance between an insulator and a winding contained in the insulator. The ignition device has a cylindrical insulator and a resin layer. The insulator has an opening portion at one end and a bottom portion at the other end. The insulator contains one of a primary winding and a secondary winding. The resin layer is formed by charging a resin in the clearance between the insulator and one of the windings. The diameter of the inner periphery of the insulator gradually increases from the opening portion to the bottom portion. When the resin layer shrinks from the opening portion toward the bottom portion of the insulator, the resin layer can shrink without getting snagged on the inner periphery of the insulator.

Abstract: An ignition coil for supplying a high voltage to a spark plug is mainly composed of a cylindrical casing, an outer coil wound around an outer spool and an inner coil wound around an inner spool. The outer coil wound around the outer spool and the inner coil wound around the inner spool are coaxially disposed in the cylindrical casing. Spaces in the cylindrical casing including a first space between the inner coil and the outer spool and a second space between the outer coil and the cylindrical casing are filled with insulating resin. After the resin is supplied into the cylindrical casing, the coils are inserted into the casing containing the resin therein. Accordingly, the resin can be quickly supplied from a wide opening, and the resin can enter into spaces between coils even these spaces are small.

Abstract: An ignition device for an internal combustion engine has a spark plug, an ignition coil, a housing and a mounting portion. The spark plug is for discharging a current to ignite an air-fuel mixture in a combustion chamber of the internal combustion engine. The ignition coil is for supplying the current to the spark plug. The housing encloses the spark plug and the ignition coil therein. The housing has a mounting portion to be disposed in a mounting hole provided in a cylinder head of the internal combustion engine. The mounting portion includes a screw portion a non-screw portion. The screw portion is to be screw-fastened to the mounting hole. The non-screw portion is not to be screw-fastened to the mounting hole.

Abstract: An ignition device for an internal combustion engine has a primary and secondary coils of an ignition coil, a center and ground electrodes of a spark plug, a cylinder shaped insulator and a cylinder shaped tube. The center electrode is disposed apart from the secondary coil in a longitudinal direction of the ignition device. The insulator is made of an insulating material and has a coil surrounding portion surrounding the secondary coil and a plug surrounding portion surrounding the center electrode. The primary coil is wound on an outer circumferential face of the coil surrounding portion. The ground electrode is disposed on an outer circumferential face of the plug surrounding portion. The tube is made of a magnetic material and has a coil covering portion covering the primary coil and a plug covering portion covering the plug surrounding portion and the ground electrode.

Abstract: An internal combustion engine ignition device has a resin layer in a clearance between an insulator and a winding contained in the insulator. The ignition device has a cylindrical insulator and a resin layer. The insulator has an opening portion at one end and a bottom portion at the other end. The insulator contains one of a primary winding and a secondary winding. The resin layer is formed by charging a resin in the clearance between the insulator and one of the windings. The diameter of the inner periphery of the insulator gradually increases from the opening portion to the bottom portion. When the resin layer shrinks from the opening portion toward the bottom portion of the insulator, the resin layer can shrink without getting snagged on the inner periphery of the insulator.