Denso Corporation

Kazutoyo Osuka

Kazuhide Kawai

Norihiro Adachi

Jyunichi Wada

Koji Tsunenaga

Atsuyuki Konishi

Shunichi Takeda

Katsunori Akimoto

Yoshitaka Sato

Junichi Wada

Masafuyu Sano

Yoshihiro Shimoide

Takashi Nagata

Masahiro Kondo

Kaneo Buma

Hidetoshi Nakashima

Hiroyuki Wakabayashi

Masahiro Inagaki

Masahiko Aoyama

Norihito Fujiyama

Hajime Kasai

Takashi Tauchi

Osamu Sugie

Katsuhisa Kato

Tomonori Ishikawa

Hideki Oka

Shigeya Abe

Masaharu Shimohata

An ignition coil has a connector electrically connected to an external circuit, an igniter for accommodating a switching element adapted to cause a current supplied from the connector to be intermittent, a primary coil portion for generating a predetermined voltage by the intermittent current, a secondary coil portion for stepping up the generated voltage and applying the resulting voltage to an ignition plug, and a resin insulating material which hardens in between the primary coil portion and the secondary coil portion to ensure insulation between the primary coil portion and the secondary coil portion. An outer shell of the igniter is formed of the resin insulating material.

Ignition coil

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.

Small-diameter ignition coil

A resin composition includes a thermosetting resin and a filler dispersed in the thermosetting resin. A filler particle size curve represents a small-diameter peak, a large-diameter peak having a higher frequency than that of the small-diameter peak, and a valley which is positioned between the small-diameter peak and the large-diameter peak and has a lower frequency than that of the small-diameter peak. An ignition coil device allows the resin composition to penetrate into gaps between turns of a coil wire.

Resin composition and ignition coil device using the same

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 () in a projection portion () 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 (). Accordingly, a frontal projected area of the projection portion () 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 () at the forming time, and a convoluted void and a weld are hard to be generated. Accordingly, since it is possible to prevent a mechanical strength in a root portion of the projection portion () from being reduced, it is possible to previously prevent a crack from being generated in the root portion of the projection portion (the collar portion) () due to a thermal stress so as to reduce an insulating property.

Ignition coil for internal combustion engine

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.

An ignition coil ( ) having a case ( ), a core ( ) installed in the case, a primary spool ( ) disposed substantially coaxially around an outer circumference of the core within the case, a primary coil ( ) comprising a wire wound around the primary spool, a secondary spool ( ) disposed substantially coaxially around the outer circumference of the core within the case, a secondary coil ( ) comprising a wire wound around the secondary spool and a resin insulating material ( ) filled within the case, the ignition coil being characterized in that the spool of the primary and the secondary spools which is disposed between the secondary coil and the core and/or which is disposed between the secondary coil and the primary coil comprises a base resin having an adhesive strength to the resin insulating material which is less than that provided by polybutylene terephthalate and an insulation breakdown voltage which exceeds that provided by polyphenylene sulfide.

Internal combustion engine ignition coil, and method of producing the same

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 ( ) in a projection portion ( ) 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 ( ). Accordingly, a frontal projected area of the projection portion ( ) 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 ( ) at the forming time, and a convoluted void and a weld are hard to be generated. Accordingly, since it is possible to prevent a mechanical strength in a root portion of the projection portion ( ) from being reduced, it is possible to previously prevent a crack from being generated in the root portion of the projection portion (the collar portion) ( ) due to a thermal stress so as to reduce an insulating property.

Ingition coil for internal combustion engine

An ignition coil according to the invention is an ignition coil having a case and a coil portion accommodated in the case. The case comprises a base resin whose dielectric breakdown voltage exceeds that of polyphenylene sulfide and whose spiral flow length exceeds that of polybutyrene terphthalate. As the base resin has a high fluidity, there is only a limited risk that a defect such as a weld line is caused when molding a thin case. In addition, while the thickness of the case and the electrical insulation properties are in proportion to each other, the case comprising the base resin can ensure sufficient electrical insulation properties even if the case is formed thin.

An ignition coil includes a housing which contains a central core portion, an inner spool having a first winding, and an outer spool having a second winding. The inner spool extends outward of the central core portion. The outer spool extends outward of the inner spool. A locating member includes a locating rib adjacent to an upper portion of the central core portion. The locating rib is in a gap between the inner spool and the central core portion, and locates the inner spool and the central core portion relative to each other. Insulating resin injected into the housing provides insulation among parts in the housing. At least one of the inner spool and the locating member has a void-escape passage which connects the gap and an outside of the inner spool with each other, and which allows a void to escape from the injected insulating resin in the gap.

An ignition coil includes a center core, a primary coil a secondary coil, a coil housing, a tower housing disposed under the coil housing, and a high tension terminal disposed inside the tower housing. The high tension terminal has an upper flange disposed at a first circumferential gap opposite the inside surface of the tower housing and a middle barrel disposed at a second circumferential gap opposite the inside surface of the coil housing. The first circumferential gap is made smaller than the second circumferential gap. The tower housing or the upper flange has a void-purging passage for purging air from the insulation resinous members when filled in the coil housing.

Resin-insulated ignition coil

A gate to mold a primary spool of an ignition coil device is placed at a part which does not oppose a main part of a secondary coil in the primary spool, that is, at a part other than a coil winding portion. It is preferred to use a resin having a high dielectric withstanding voltage and a high flowability, such as polybutylene terephthalate (PBT) or polyethylene terephthalate (PET), polyphenylene oxide (PPO)/polystyrene (PS), or liquid crystal polymer. By arranging the gate except at the winding portion, resin deterioration or cracks occur only at a part which does not oppose the secondary coil, that is, at a part where a high voltage from the secondary coil is relatively low. An adequate dielectric withstanding voltage is ensured without winding an insulation tape around the winding portion.

Method of injection-molding coil spool of ignition coil device

In a stick-type ignition coil device for engines, a primary spool is disposed outside a secondary coil. The primary spool is made of PBT (polybuthylene telephthalate) having a low melting viscosity and a high flowability as a resin base material. The resin base material is admixed with an olefin rubber in 5 wt. %, glass fibers in 12.5 wt. % and silica in 12.5 wt. %. A primary coil comprises a wire body coated with PET (polyethylene telephthalate), silicone or wax as a separating member, and is wound around the primary spool. The growth of trees in the primary spool restricted even when electrical discharges occur between a secondary coil and the primary coil and the primary spool is eroded by the electrical discharges, because silica is added in the primary spool.

Ignition coil device having spool including glass fiber and silica

A stick-type ignition coil to be directly connected to a spark plug via a spring. A high tension case containing a high tension terminal and a spring is integrally connected to the bottom end of a high tension generating portion of the ignition coil. The high tension terminal and the spring are separately supported in the high tension case before the spark plug is connected to the ignition coil. When the spark plug is connected, the spring is compressed and contacts the high tension terminal, thereby making electrical contact between the ignition coil and the spark plug. Since the spring and the high tension terminal are supported on separate positions in the case, the spring can be properly compressed without being distorted or jammed between the high tension terminal and the case.

Ignition coil having spring for connecting the same to spark plug

An ignition coil that can be easily assembled, that assures co-axial alignment of a primary coil, a secondary coil and a center core part, and that generates desired high voltage. A core body is formed to have an outer diameter larger than that of a permanent magnet so that the permanent magnet will not protrude out of the outer peripheral face of the core body. Accordingly, when the center core part is inserted into a secondary spool, the center core part is not caught by the secondary spool and may be readily inserted and assembled therewith. Also, because no bulge is created at the center core part, it is possible to prevent the center core part from tilting within the secondary spool and to readily assure the co-axial alignment of the primary spool, the secondary spool and the center core part. Thus, voltage generated by the secondary coil is prevented from dropping, and high voltage may be applied to the ignition plug.

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Gamagori, Japan

Kazutoyo Osuka