An igniter that has a large ignition power and an electromagnetic wave resonance structure with a small reflected power is provided. An igniter comprises a first rectangular substrate and a second rectangular substrate each having a longitudinal side, and at least one intermediate substrate arranged between the first substrate and the second substrate and having a longitudinal side which is shorter than each longitudinal side of the first substrate and the second substrate, the first substrate has an input part configured to receive an input of an electromagnetic wave from an outside, a first electrode, and an electromagnetic wave transmission line that connects the input part to the first electrode, each of the first electrode and the electromagnetic wave transmission line being provided at a surface of the first substrate on a side of the at least one intermediate substrate, the second substrate has an electromagnetic wave resonator and a second electrode that is electrically connected to the electromagnetic wave resonator, each of the electromagnetic wave resonator and a second electrode being provided at a surface of the second substrate on a side of the at least one intermediate substrate, and a space is formed between the first substrate and the second substrate at a position at which the at least one intermediate substrate does not exist therebetween, such that the first electrode and the second electrode are faced each other and located away from each other across the space and a part of the electromagnetic wave transmission line and a part of the resonator are faced each other and located away from each other across the space.

An igniter that has a large ignition power and an electromagnetic wave resonance structure with a small reflected power is provided. An igniter comprises a first rectangular substrate and a second rectangular substrate each having a longitudinal side, and at least one intermediate substrate arranged between the first substrate and the second substrate and having a longitudinal side which is shorter than each longitudinal side of the first substrate and the second substrate, the first substrate has an input part configured to receive an input of an electromagnetic wave from an outside, a first electrode, and an electromagnetic wave transmission line that connects the input part to the first electrode, each of the first electrode and the electromagnetic wave transmission line being provided at a surface of the first substrate on a side of the at least one intermediate substrate, the second substrate has an electromagnetic wave resonator and a second electrode that is electrically connected to the electromagnetic wave resonator, each of the electromagnetic wave resonator and a second electrode being provided at a surface of the second substrate on a side of the at least one intermediate substrate, and a space is formed between the first substrate and the second substrate at a position at which the at least one intermediate substrate does not exist therebetween, such that the first electrode and the second electrode are faced each other and located away from each other across the space and a part of the electromagnetic wave transmission line and a part of the resonator are faced each other and located away from each other across the space.

By grounding a metal first housing, radiation noise generated from the coupling circuit is shielded. Further, by enclosing the first housing in a metal second housing in a manner such that the first housing and the second housing do not come into contact with each other, and grounding the second housing by connecting the second housing to an engine block, radiation noise generated by the capacitive component between the coupling circuit and the first housing is shielded by the second housing. As a result, the influence of this noise on peripheral devices of the high frequency discharge ignition device can be suppressed.

By grounding a metal first housing, radiation noise generated from the coupling circuit is shielded. Further, by enclosing the first housing in a metal second housing in a manner such that the first housing and the second housing do not come into contact with each other, and grounding the second housing by connecting the second housing to an engine block, radiation noise generated by the capacitive component between the coupling circuit and the first housing is shielded by the second housing. As a result, the influence of this noise on peripheral devices of the high frequency discharge ignition device can be suppressed.

An igniter assembly comprising an ignition coil assembly connected to a firing end assembly by an extension, with a valve assembly disposed in a pressure chamber of the extension, is provided. The valve assembly includes a valve stem biased toward the ignition coil assembly by a spring to seal the pressure chamber. The valve assembly is used to evacuate contents from the pressure chamber by pressing the valve stem toward the spring and allowing contents of the pressure chamber to travel through and past the valve stem and out of the pressure chamber. The valve assembly is also used to fill the pressure chamber with an insulating medium by pressing the valve stem toward the spring and allowing the insulating medium to travel through and past the valve stem and into the pressure chamber after evacuating the contents out of the pressure chamber.

An aim of the present invention is, in a plug for high frequency emission disposed at an end of a casing having an emission antenna, to suppress a high frequency noise emitted from the emission antenna. The present invention is directed to a plug for high frequency emission including a transmission line for transmitting an electromagnetic wave, an emission antenna for emitting the electromagnetic wave supplied via the transmission line, and a casing constituted by a cylindrical shaped conductor, provided with the emission antenna at one end of the casing, and accommodating therein the transmission line extending from the emission antenna toward the other end of the casing. Inside of the casing, a central conductor electrically connected to the emission antenna and an outer conductor spaced apart from and surrounding the central conductor are embedded in an insulator so as to collectively constitute the transmission line, and the outer conductor is disposed in and held in non-contact with the casing.

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.

A corona igniter assembly 20 comprises an ignition coil assembly 22, a firing end assembly 24, and a metal tube 26 connecting the ignition coil assembly 22 to the firing end assembly 24. A rubber boot 28 is disposed in the metal tube 26 and compressed symmetrically between a coil output member 30 of the ignition coil assembly 22 and an insulator 42 of the firing end assembly 24. Thus, the rubber boot 28 fills any air gaps and provides a hermetic seal between the ignition coil assembly 22 and the firing end assembly 24 to prevent unwanted corona discharge from forming from those air gaps.

A corona ignition assembly comprising a plurality of different insulators disposed between an ignition coil assembly and firing end assembly is provided. A high voltage center electrode extends longitudinally between an igniter central electrode and the ignition coil assembly. A high voltage insulator formed of a fluoropolymer surrounds the high voltage center electrode, and a firing end insulator formed of alumina surrounds the igniter central electrode. According to one embodiment, a glue formed of a compliant and insulating material, such as a silicon-based material, forms a seal between the high voltage insulator and the firing end insulator. According to another embodiment, a dielectric compliant insulator is disposed between the high voltage insulator and the ignition coil assembly, and the glue forms a seal therebetween. The glue fills air gaps to prevent unwanted corona discharge, and thus extends the life of the materials and directs energy to the firing end.

A corona ignition assembly comprising a plurality of different insulators disposed between an ignition coil assembly and firing end assembly is provided. A high voltage center electrode extends longitudinally between an igniter central electrode and the ignition coil assembly. A high voltage insulator formed of a fluoropolymer surrounds the high voltage center electrode, and a firing end insulator formed of alumina surrounds the igniter central electrode. According to one embodiment, a glue formed of a compliant and insulating material, such as a silicon-based material, forms a seal between the high voltage insulator and the firing end insulator. According to another embodiment, a dielectric compliant insulator is disposed between the high voltage insulator and the ignition coil assembly, and the glue forms a seal therebetween. The glue fills air gaps to prevent unwanted corona discharge, and thus extends the life of the materials and directs energy to the firing end.