Abstract: An ignition system for an internal combustion engine includes an ignition coil, electric power supply circuit, a switching transistor, engine condition detecting element or unit that detects a signal relating to flow speed of air-fuel-mixture gas in the engine, and ignition control unit that controls the switching transistor to provide multiple ignition sparks in a predetermined ignition period. The ignition control unit controls the switching transistor to maintain each of the ignition sparks according to the signal relating to the flow speed of air-fuel-mixture gas in the engine to maintain sufficient spark energy for igniting the air-fuel mixture gas.

Abstract: An ignition system for an internal combustion engine includes an ignition coil, electric power supply circuit, a switching transistor, engine condition detecting element or unit that detects a signal relating to flow speed of air-fuel-mixture gas in the engine, and ignition control unit that controls the switching transistor to provide multiple ignition sparks in a predetermined ignition period. The ignition control unit controls the switching transistor to maintain each of the ignition sparks according to the signal relating to the flow speed of air-fuel-mixture gas in the engine to maintain sufficient spark energy for igniting the air-fuel mixture gas.

Abstract: An ignition coil includes a primary coil, a secondary coil, a spool, and a center core. The primary coil and the secondary coil are arranged substantially coaxially with each other. The secondary coil is on an inner side of the primary coil. The secondary coil is wound around the spool. The center core is inside of the spool. The spool has a tapered inner surface, which is axially defined at least partially in the spool. The tapered inner surface has the diameter that increases as being distant from a high voltage tip end of the secondary coil on the high voltage side of the secondary coil. The center core has a tapered outer surface, which is axially defined at least partially in the center core. The tapered outer surface has the diameter that increases as being distant from the high voltage tip end of the secondary coil.

Abstract: A stick-shaped ignition coil includes a primary and secondary coils, a plurality of annular protrusions, a thin film sheet, a sub-assembly and a case. The annular protrusions are integrally formed on the outer circumferential periphery of the upper end portion of the primary coil arranged on the radially outer side. The thin film sheet covers the primary coil and the outer circumferential periphery of the plurality of annular protrusions. The sub-assembly is press-inserted to the outer circumferential periphery of the plurality of annular protrusions via the thin film sheet. The sub-assembly, which is electrically insulative, supports a lead portion of the primary winding. The case is press-inserted to the outer circumferential periphery of the cylindrical member.

Abstract: An ignition coil includes a primary coil, a secondary coil, a spool, and a center core. The primary coil and the secondary coil are arranged substantially coaxially with each other. The secondary coil is on an inner side of the primary coil. The secondary coil is wound around the spool. The center core is inside of the spool. The spool has a tapered inner surface, which is axially defined at least partially in the spool. The tapered inner surface has the diameter that increases as being distant from a high voltage tip end of the secondary coil on the high voltage side of the secondary coil. The center core has a tapered outer surface, which is axially defined at least partially in the center core. The tapered outer surface has the diameter that increases as being distant from the high voltage tip end of the secondary coil.

Abstract: An ignition coil is constructed of a center core, a primary coil, a secondary coil, and an outer circumferential core. The center core and the outer circumferential core are connected with each other via a first magnetoresistive member on one axial end side. The center core and the outer circumferential core are connected with each other via a second magnetoresistive member on the other axial end side. A permanent magnet is arranged in an axially central portion of the center core. A magnetic passage is formed of the center core, the permanent magnet, the first magnetoresistive member, the outer circumferential core, and the second magnetoresistive member. Magnetic flux generated by the primary coil is reduced through the first and second magnetoresistive members, and is reverse-biased by the permanent magnet.

Abstract: A small-diameter ignition coil includes a center core, a primary coil, a secondary coil, and a thin film tube. The primary and secondary coils are arranged on an outer circumferential side with respect to the center core. The thin film tube has a cylindrical shape. The thin film tube is arranged on an outer circumferential side with respect to one of the primary coil and the secondary coil that is arranged on an outer circumferential side with respect to the other of the primary coil and the secondary coil. The thin film tube is thermally resistive and electrically insulative. The thin film tube has wall thickness that is equal to or less than 0.35 mm. An electrically insulative resin is filled in a gap formed between the thin film tube and one of the primary coil and the secondary coil, which is radially adjacent to the thin film tube.

Abstract: A stick-shaped ignition coil includes a primary and secondary coils, a plurality of annular protrusions, a thin film sheet, a sub-assembly and a case. The annular protrusions are integrally formed on the outer circumferential periphery of the upper end portion of the primary coil arranged on the radially outer side. The thin film sheet covers the primary coil and the outer circumferential periphery of the plurality of annular protrusions. The sub-assembly is press-inserted to the outer circumferential periphery of the plurality of annular protrusions via the thin film sheet. The sub-assembly, which is electrically insulative, supports a lead portion of the primary winding. The case is press-inserted to the outer circumferential periphery of the cylindrical member.

Abstract: A small-diameter ignition coil includes a center core, a primary coil, a secondary coil, and a thin film tube. The primary and secondary coils are arranged on an outer circumferential side with respect to the center core. The thin film tube has a cylindrical shape. The thin film tube is arranged on an outer circumferential side with respect to one of the primary coil and the secondary coil that is arranged on an outer circumferential side with respect to the other of the primary coil and the secondary coil. The thin film tube is thermally resistive and electrically insulative. The thin film tube has wall thickness that is equal to or less than 0.35 mm. An electrically insulative resin is filled in a gap formed between the thin film tube and one of the primary coil and the secondary coil, which is radially adjacent to the thin film tube.

Abstract: An ignition coil is constructed of a center core, a primary coil, a secondary coil, and an outer circumferential core. The center core and the outer circumferential core are connected with each other via a first magnetoresistive member on one axial end side. The center core and the outer circumferential core are connected with each other via a second magnetoresistive member on the other axial end side. A permanent magnet is arranged in an axially central portion of the center core. A magnetic passage is formed of the center core, the permanent magnet, the first magnetoresistive member, the outer circumferential core, and the second magnetoresistive member. Magnetic flux generated by the primary coil is reduced through the first and second magnetoresistive members, and is reverse-biased by the permanent magnet.

Abstract: In a stick coil, there is disclosed an ignition coil for an internal combustion engine which can prevent a crack (a collar leak) from being generated due to a thermal stress. In this ignition coil, the structure is made such that a size (L) of a portion which is in parallel to an axial direction of a primary spool (121) in a projection portion (121b) is larger than a size (T) of a portion which is in parallel to an orthogonal direction to the axial direction of the primary spool (121). Accordingly, a frontal projected area of the projection portion (121b) as seen from a flowing direction of a resin becomes small, a resin flow is hard to get out of order at a time when the resin flows through a portion corresponding to the projection portion (121b) at the forming time, and a convoluted void and a weld are hard to be generated.

Abstract: The ignition coil in this invention has a coil portion and a high voltage tower portion. The coil portion has a primary coil, a secondary coil, and a coil case. The high voltage tower portion has a high voltage spring which attaches to the terminal of the ignition plug under the coil in the central portion of the ignition coil. A feature of the ignition coil is that a secondary terminal composed of a connector portion connected with a secondary winding and an attaching portion directly attaches at the end of the high voltage spring under the coil portion. Since the secondary terminal functions as a terminal of the high voltage spring, the high voltage spring terminal, such as in the prior art, can be eliminated. An air outlet passage is also formed at the high voltage end of the secondary spool.

Abstract: An ignition coil has an outer coil unit, an inner coil unit, a coil case in which the outer and inner coil units are housed and a tower case accommodating lower parts of outer and inner spools. The outer spool is made of resin material whose bonding strength to resin insulating material, with which the tower case is filled, is weak. An axial leading end of the outer spool is positioned axially away from a reference position by a distance equal to or shorter than 60% of a reference length or by a distance equal to or longer than 90% of the reference length. With this ignition coil, cracks are suppressed on the resin insulating material opposed to the axial leading end of the outer spool otherwise caused by thermal stress.

Abstract: In a stick coil, there is disclosed an ignition coil for an internal combustion engine which can prevent a crack (a collar leak) from being generated due to a thermal stress. In this ignition coil, the structure is made such that a size (L) of a portion which is in parallel to an axial direction of a primary spool (121) in a projection portion (121b) is larger than a size (T) of a portion which is in parallel to an orthogonal direction to the axial direction of the primary spool (121). Accordingly, a frontal projected area of the projection portion (121b) as seen from a flowing direction of a resin becomes small, a resin flow is hard to get out of order at a time when the resin flows through a portion corresponding to the projection portion (121b) at the forming time, and a convoluted void and a weld are hard to be generated.

Abstract: An ignition coil has a case and a central core placed in the case. A secondary spool is wound with a secondary coil and placed outside the central core in the case. A cylindrical primary spool is wound with a primary coil and placed outside the secondary spool in the case. A resin insulator is filled in the case to maintain the insulation between each member. Air layer is partitioned in at least one of a gap between the central core and the secondary spool and a gap between the primary spool and the case.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine, and a base member detachably engages and holds the ignition coils at corresponding positions, which correspond to positions of the plug holes. Disengaging force for disengaging each ignition coil and the base member from each other is set to be smaller than disengaging force for disengaging each ignition coil and the corresponding one of the spark plugs from each other.

Abstract: In an ignition coil assembly, a plurality of ignition coils is arranged to be electrically connected to spark plugs received in plug holes of an engine, and a base member detachably engages and holds the ignition coils at corresponding positions, which correspond to positions of the plug holes. Disengaging force for disengaging each ignition coil and the base member from each other is set to be smaller than disengaging force for disengaging each ignition coil and the corresponding one of the spark plugs from each other.

Abstract: In an ignition coil having an outer coil unit, an inner coil unit, a coil case in which the outer and inner coil units are housed and a tower case accommodating lower parts of outer and inner spools, the outer spool is made of resin material whose bonding strength to resin insulating material, with which the tower case is filled, is weak and an axial leading end of the outer spool is positioned axially away from a reference position by a distance equal to or shorter than 60% of a reference length or by a distance equal to or longer than 90% of the reference length. With this ignition coil, cracks hardly occur on the resin insulating material opposed to the axial leading end of the outer spool by thermal stress.

Abstract: The ignition coil in this invention has a coil portion and a high voltage tower portion. The coil portion has a primary coil, a secondary coil, and a coil case. The high voltage tower portion has a high voltage spring which attaches to the terminal of the ignition plug under the coil in the central portion of the ignition coil. A feature of the ignition coil is that a secondary terminal composed of a connector portion connected with a secondary winding and an attaching portion directly attaches at the end of the high voltage spring under the coil portion. Since the secondary terminal functions as a terminal of the high voltage spring, the high voltage spring terminal, such as in the prior art, can be eliminated.

Abstract: An ignition coil has a case and a central core placed in the case. A secondary spool is wound with a secondary coil and placed outside the central core in the case. A cylindrical primary spool is wound with a primary coil and placed outside the secondary spool in the case. A resin insulator is filled in the case to maintain the insulation between each member. Air layer is partitioned in at least one of a gap between the central core and the secondary spool and a gap between the primary spool and the case.