Spark plug has first and second electrodes. First electrode has tip principally made of noble metal and base material principally made of Ni. The tip is joined to the base material through fusion portion. Second electrode faces discharge surface of the tip. The fusion portion has overlap portion where first interface between the tip and the fusion portion and second interface between the base material and the fusion portion overlap in first direction perpendicular to the discharge surface. When viewing cross section which passes through a center of gravity of the overlap portion projected onto virtual surface parallel to the discharge surface and is perpendicular to the discharge surface, noble metal content is greater than 50 mass % at one end portion of the overlap portion in second direction extending along the discharge surface, and Ni content is greater than 50 mass % at the other end portion of the overlap portion.

Spark plug has first and second electrodes. First electrode has tip principally made of noble metal and base material principally made of Ni. The tip is joined to the base material through fusion portion. Second electrode faces discharge surface of the tip. The fusion portion has overlap portion where first interface between the tip and the fusion portion and second interface between the base material and the fusion portion overlap in first direction perpendicular to the discharge surface. When viewing cross section which passes through a center of gravity of the overlap portion projected onto virtual surface parallel to the discharge surface and is perpendicular to the discharge surface, noble metal content is greater than 50 mass % at one end portion of the overlap portion in second direction extending along the discharge surface, and Ni content is greater than 50 mass % at the other end portion of the overlap portion.

The invention relates to a semiconductor body revolving around a main axis (A) for a spark plug of a turbine engine, the semiconductor body comprising a baseplate and an upper portion extending from the baseplate along the main axis, the baseplate comprising a bottom surface substantially defined in a plane perpendicular to the main axis and a first conical surface intended to cooperate by form-fitting at least partially with a contact surface of an outer electrode of the spark plug. According to the invention, the upper portion comprises an interface located opposite the bottom surface along the main axis (A) and featuring a profile that is at least partially corrugated.

An ignition device according to the present invention includes: an ignition plug, which includes a first electrode, a second electrode, and a dielectric body arranged between the electrodes; an AC power supply configured to generate an AC voltage to be applied between the electrodes; a thermal plasma detection portion configured to output a thermal plasma occurrence signal when thermal plasma has occurred between the electrodes; and an application time period determination portion configured to determine an application time period for the AC voltage during one cycle of the internal combustion engine in advance before the application, and when the thermal plasma occurrence signal is received while the AC voltage is being applied based on the application time period, change the application time period so as to shorten the application time period.

A pre-chamber spark plug for an internal combustion engine having a surface discharge spark gap that is generally located at a rearward end of a pre-chamber and is configured so that sparking components will have minimal electrode obstruction and promote unhindered gas exchange between the pre-chamber and a main combustion chamber. According to one embodiment, the surface discharge spark gap includes a radial sparking portion where a majority of the sparking occurs in a generally radial direction. According to another embodiment, the surface discharge spark gap includes both a radial sparking portion and an axial sparking portion so that sparking occurs in both radial and axial directions, respectively.

A pre-chamber spark plug for an internal combustion engine having a surface discharge spark gap that is generally located at a rearward end of a pre-chamber and is configured so that sparking components will have minimal electrode obstruction and promote unhindered gas exchange between the pre-chamber and a main combustion chamber. According to one embodiment, the surface discharge spark gap includes a radial sparking portion where a majority of the sparking occurs in a generally radial direction. According to another embodiment, the surface discharge spark gap includes both a radial sparking portion and an axial sparking portion so that sparking occurs in both radial and axial directions, respectively.

A pre-chamber spark plug having a shell, an insulator disposed at least partially within the shell, a center electrode disposed at least partially within the insulator, a ground electrode forming a spark gap with the center electrode, and a pre-chamber cap connected to the shell and forming a pre-chamber. The pre-chamber cap includes two or more openings that are configured so that at least one inflowing fuel-air mixture jet is directed to a pre-chamber wall gap so as to flush out or remove gas from a previous ignition cycle. The two or more openings are angled so that a first inflowing fuel-air mixture jet of a first opening does not intersect with a second inflowing fuel air-mixture jet of a second opening.

A pre-chamber spark plug for an internal combustion engine having a surface discharge spark gap that is generally located at a rearward end of a pre-chamber and is configured so that sparking components will have minimal electrode obstruction and promote unhindered gas exchange between the pre-chamber and a main combustion chamber. According to one embodiment, the surface discharge spark gap includes a radial sparking portion where a majority of the sparking occurs in a generally radial direction. According to another embodiment, the surface discharge spark gap includes both a radial sparking portion and an axial sparking portion so that sparking occurs in both radial and axial directions, respectively.

A pre-chamber spark plug for an internal combustion engine having a surface discharge spark gap that is generally located at a rearward end of a pre-chamber and is configured so that sparking components will have minimal electrode obstruction and promote unhindered gas exchange between the pre-chamber and a main combustion chamber. According to one embodiment, the surface discharge spark gap includes a radial sparking portion where a majority of the sparking occurs in a generally radial direction. According to another embodiment, the surface discharge spark gap includes both a radial sparking portion and an axial sparking portion so that sparking occurs in both radial and axial directions, respectively.

A spark plug for generating an axially extending surface spark between a sparking tip of the center electrode and a seal supporting sparking projection located at an internal step portion of the metal shell. In one embodiment, the spark plug is a pre-chamber spark plug having a pre-chamber cap attached to a distal end of the metal shell. The spark plug can allow for unobstructed flame propagation through the pre-chamber, without having the flame obstructed by narrow gaps or a separate ground electrode.