An ignition coil includes a primary coil, a secondary coil, a center core, an outer core, an igniter, a coil case and an electrically-insulative fixation resin. On an interior surface of the coil case on a bottom part side in a mounting direction, there is formed a case-side rib to protrude from the interior surface of the coil case to a high-voltage side in an axial direction. The case-side rib has a taper shape such that the protruding amount of the case-side rib to the high-voltage side in the axial direction increases in the mounting direction toward the bottom part side. The case-side rib is arranged to abut a corner portion of the igniter on the bottom part side in the mounting direction and on a low-voltage side in the axial direction and thereby press the igniter against the outer core.

An ignition coil includes: a center core; a primary coil wound around the center core; a secondary coil wound around the primary coil; a plurality of side cores, which are arranged around the secondary coil, and are coupled to the center core to form a closed magnetic path; a magnet inserted between the plurality of side cores; an igniter configured to control supply and interruption of a current to the primary coil; a case configured to accommodate the center core, the primary coil, the secondary coil, the plurality of side cores, the magnet, and the igniter; and insulating resin filled in the case. The side cores include a wide portion and a narrow portion. The magnet is inserted into the wide portion. The igniter is arranged between the narrow portion and the case

An ignition coil includes a primary coil, a secondary coil, a center core, a magnet body and an outer peripheral core. The outer peripheral core is provided with a first opposite side, a second opposite side and a coupling side, the first opposite side facing the magnet body from an opposite side of the center core, the second opposite side facing the center core from the opposite side of the magnet body, the coupling side coupling the first opposite side with the second opposite side. The center core has a magnet side flange portion disposed at an end portion in a magnet body side, protruding in a protrusion direction. A thick portion is formed at both of a part of the first opposite side and a part of the coupling side, and a thickness of the thick portion being larger than a minimum thickness of the second opposite side.

An ignition coil includes a center core, a first core member, and a second core member. The first core member includes a first core-facing portion facing a front core surface of the center core and a first core side portion extending rearward from the first core-facing portion. The second core member includes a second core-facing portion facing a rear core surface of the center core and a second core side portion extending frontward from the second core-facing portion. The first core-facing portion has an end surface contacting a portion of the second core side portion to create a first contact region. Similarly, the second core-facing portion has an end surface contacting a portion of the first core side portion to create a second contact region. The first and second contact regions are shaped to approach frontward close to the first core side portion. This structure enhances productivity of the ignition coil.

An ignition coil has primary and secondary coils, a central core and a pair of split cores. One of the split cores has a first opposing face orthogonal to a coil axial direction X facing a core front end face of the central core in the coil axial direction X. The respective split cores have second opposing surfaces mutually facing each other in a lateral direction Y at a rear end of the central core. At least one of the second opposing surfaces and one of rear end surfaces of the central core contacting the least one of the second opposing surfaces collectively constitute a pair of oblique surfaces and come to close to the other one of the second opposing surfaces in the lateral direction Y as a portion of each of the oblique surfaces recedes further from the first opposing face in the coil axial direction X.

An ignition coil for an internal combustion engine includes: a center core arranged on an inner side of a primary coil and an inner side of a secondary coil; a side core arranged on an outer side of the primary coil and an outer side of the secondary coil, and combined with the center core to form a closed magnetic circuit; one or a plurality of gaps provided between the center core and the side core, or in the side core; and a magnet arranged in each of the one or a plurality of gaps, in which a sum of cross-sectional areas of the respective magnets is set to be three times or more and less than seven times of a cross-sectional area of the center core.

An internal combustion engine ignition coil includes: a center core; a primary coil provided on an outer side of the center core; a secondary coil provided on an outer side of the primary coil; and a side core provided on an outer side of the primary coil and the secondary coil and formed by stacked electromagnetic steel sheets, the side core having one contact portion in contact with one end surface of the center core and another contact portion in contact with another end surface of the center core with a magnet therebetween. The side core is composed of a plurality of side core portions fitted to each other to be movable relative to each other in a longitudinal direction of the center core.

An ignition coil for use in an internal combustion engine includes a primary coil, a secondary coil, a core, and a magnet. The core creates a closed magnetic circuit through which magnetic flux produced upon energization of the primary coil flows. The core has formed therein a gap through which the magnetic circuit passes. The magnet is disposed in the gap and has magnetic domains whose magnetization vectors are at least partially oriented obliquely relative to a gap direction. The orientation of the magnetization vectors in the magnet minimizes an energy loss when primary energy is transformed into secondary energy.

An ignition coil unit comprises a primary coil, a secondary coil, a housing and a terminal metallic part. A portion of the terminal metallic part is buried in a burying wall formed in the housing. The other portion of the terminal metallic part is disposed in an interior of the housing. The terminal metallic part includes an inner terminal extended from a burying wall main surface and at least partially disposed in the interior of the housing. The inner terminal includes a terminal first portion extended along a normal line of the terminal burying wall main surface from the terminal burying wall main surface to the interior of the housing and a terminal second portion extended upward from the terminal first portion. The housing includes a protrusion to horizontally protrude from the terminal burying wall main surface while facing the bottom surface of the terminal first portion.

An ignition coil unit comprises a primary coil, a secondary coil, a housing and a terminal metallic part. A portion of the terminal metallic part is buried in a burying wall formed in the housing. The other portion of the terminal metallic part is disposed in an interior of the housing. The terminal metallic part includes an inner terminal extended from a burying wall main surface and at least partially disposed in the interior of the housing. The inner terminal includes a terminal first portion extended along a normal line of the terminal burying wall main surface from the terminal burying wall main surface to the interior of the housing and a terminal second portion extended upward from the terminal first portion. The housing includes a protrusion to horizontally protrude from the terminal burying wall main surface while facing the bottom surface of the terminal first portion.