An ignition device is provided, the ignition device comprises a coaxial structural body comprising an inner conductor 2, an outer conductor 3, and an insulator 4 that insulates both the conductors 2 and 3, which are coaxially provided with one another along an axial direction. A connection terminal 5 is arranged at one axial end side of the coaxial structural body and connecting the inner conductor 2 and the outer conductor 3 to the electromagnetic wave oscillator MW. The inner conductor 2 has a linearly extended part protruding at another axial end side of the coaxial structural body extending outwards from the outer conductor 3 in the axial direction and a spirally extended part continuously extending from the linearly extended part in a reversed direction and in a spiral manner that winds around the linearly extended part of the inner conductor 2 in a predetermined number of turns around the linearly extended part such that the inner conductor 2 forms a resonance structure and the spirally extended part 20 with the resonance structure is obtained. A diameter and a length of the inner conductor 2 that is extended outwards from the outer conductor 3, and the number of turns of the spirally extended part of the inner conductor 2 are determined such that a capacitive reactance XC and an inductive reactance XL of the spirally extended part are substantially equal to each other.

An ignition system for an internal combustion engine has a power source, a transformer having first and second primary windings and a secondary winding, a connector extending from the secondary winding and adapted so as to connect with a terminal of the spark plug of the internal combustion engine, and electronic spark timing circuit cooperative with the transformer so as to activate and deactivate voltage to the first and second primary windings. The first and second primary windings are connected to the power source such that the transformer produces an alternating voltage output from the secondary winding of between 1 kHz and 100 kHz and a voltage of at least 20 kV. A forced push-pull inverter is cooperative with the electronic spark timing circuit so as to fix a frequency of voltage to the first and second primary windings.

A small-size injector having a built-in ignition device which can surely inject fuel and ignite the fuel with low electric power by the ignition device with a simple configuration is provided. The injector comprises a fuel injecting device 2 having a fuel injecting port 20 that injects the fuel, an ignition device 3 configured to ignite the injected fuel, and a casing 10 inside housing therein the fuel injecting device 2 and the ignition device 3 together. The motion device 3 is constituted of a plasma generator 3 which integrally comprises a booster 5 having a resonation structure capacity-coupled with an electromagnetic wave oscillator MW configured to oscillate an electromagnetic wave, and a discharger 6 configured to cause a discharge of a high voltage generated by the booster 5.

A small-size injector having a built-in ignition device which can surely inject fuel and ignite the fuel with low electric power by the ignition device with a simple configuration is provided. The injector comprises a fuel injecting device 2 having a fuel injecting port 20 that injects the fuel, an ignition device 3 configured to ignite the injected fuel, and a casing 10 inside housing therein the fuel injecting device 2 and the ignition device 3 together. The motion device 3 is constituted of a plasma generator 3 which integrally comprises a booster 5 having a resonation structure capacity-coupled with an electromagnetic wave oscillator MW configured to oscillate an electromagnetic wave, and a discharger 6 configured to cause a discharge of a high voltage generated by the booster 5.

A corona ignition device is described comprising a central electrode, to which at least one ignition tip leads, and an insulator, which surrounds the central electrode. According to this disclosure, provision is made for the at least one ignition tip to comprise a plurality of wires touching each other.

An ignition coil for an internal combustion engine is equipped with an assembly of a connector casing and a coil body. The coil body includes a primary winding wound around a primary spool. The connector casing has terminals each of which is equipped with a conductor fastener. The conductor fastener has a slit in which one of ends of the primary winding is fit to make an electric connection between the terminal and the primary winding. The primary spool has conductor guides and a backup support to establish alignment of each of the ends of the primary winding with one of the conductor fasteners and also to facilitate insertion of each of the ends of the primary winding into one of the conductor fasteners when the coil body is fitted into the connector casing, thereby ensuring the stability of electric connection between the primary winding and the terminal.

An ignition coil for an internal combustion engine is equipped with an assembly of a connector casing and a coil body. The coil body includes a primary winding wound around a primary spool. The connector casing has terminals each of which is equipped with a conductor fastener. The conductor fastener has a slit in which one of ends of the primary winding is fit to make an electric connection between the terminal and the primary winding. The primary spool has conductor guides and a backup support to establish alignment of each of the ends of the primary winding with one of the conductor fasteners and also to facilitate insertion of each of the ends of the primary winding into one of the conductor fasteners when the coil body is fitted into the connector casing, thereby ensuring the stability of electric connection between the primary winding and the terminal.

An ignition coil has a ferromagnetic core with a primary coil surrounding a first portion of the ferromagnetic core and a secondary coil surrounding the second portion of the ferromagnetic core. The secondary coil is wrapped around a bobbin. The bobbin has an interior receiving the second portion of the ferromagnetic core. A form is interposed between the secondary coil and the second portion of the ferromagnetic core. The form extends longitudinally along the second portion of the ferromagnetic core. The form is of a non-ferrous metal material.

An ignition coil has a ferromagnetic core with a primary coil surrounding a first portion of the ferromagnetic core and a secondary coil surrounding the second portion of the ferromagnetic core. The secondary coil is wrapped around a bobbin. The bobbin has an interior receiving the second portion of the ferromagnetic core. A form is interposed between the secondary coil and the second portion of the ferromagnetic core. The form extends longitudinally along the second portion of the ferromagnetic core. The form is of a non-ferrous metal material.

An ignition coil includes a coil main body portion, a conductive member, and a protective portion. The coil main body portion generates a high voltage. The conductive member electrically connects the coil main body portion and a terminal metal fitting of a spark plug. The conductive member is arranged inside the protective portion. The protective portion has an electrically insulating property. The conductive member includes an elastic portion that elastically deforms in a longitudinal direction of the conductive member, and a conductive terminal that is arranged on a distal end side of the elastic portion. The conductive terminal has a distal end surface that includes a concave surface or a convex surface that abuts on the terminal metal fitting of the spark plug. A contact portion between the concave surface or the convex surface and the terminal metal fitting of the spark plug has an annular shape.