A dual spark plug may include: a metal body made of metal material, an insulating body provided inside of the metal body and made of an insulating material, a pair of central electrodes provided inside of the insulating body and electrically connected with an ignition coil, and a pair of ground electrodes respectively extended from both ends the metal body, and spaced apart from ends of the pair of central electrodes by a predetermined distance.

A dual spark plug may include: a metal body made of metal material, an insulating body provided inside of the metal body and made of an insulating material, a pair of central electrodes provided inside of the insulating body and electrically connected with an ignition coil, and a pair of ground electrodes respectively extended from both ends the metal body, and spaced apart from ends of the pair of central electrodes by a predetermined distance.

A spark plug resistance element that includes at least one inorganic amorphous oxide and at least one first inorganic crystalline oxide having a relative dielectric permittivity of at most 15. A spark plug that includes at least one spark plug resistance element is also described.

A spark plug resistance element that includes at least one inorganic amorphous oxide and at least one first inorganic crystalline oxide having a relative dielectric permittivity of at most 15. A spark plug that includes at least one spark plug resistance element is also described.

This ignition coil includes: a bar-shaped resistor electrically connected to a terminal of a coil assembly via a relay; a case for storing these; and a filler filling gaps inside the case. The case includes a body, a cylindrical output portion protruding from the body, and an annular holding portion protruding inward from an inner circumferential surface of the output portion and formed integrally with the output portion. A part of the resistor is inserted into the holding portion, and thus a first internal area located on the body side with respect to the holding portion and shut off from outside is formed in an internal area of the output portion. The filler fills the first internal area.

This ignition coil includes: a bar-shaped resistor electrically connected to a terminal of a coil assembly via a relay; a case for storing these; and a filler filling gaps inside the case. The case includes a body, a cylindrical output portion protruding from the body, and an annular holding portion protruding inward from an inner circumferential surface of the output portion and formed integrally with the output portion. A part of the resistor is inserted into the holding portion, and thus a first internal area located on the body side with respect to the holding portion and shut off from outside is formed in an internal area of the output portion. The filler fills the first internal area.

The present disclosure provides, inter alia, apparatuses for preparing a suppressor seal of a spark plug insulator assembly, and processes for fabricating and/or assembling a spark plug insulator assembly using the same. Also provided are automated systems for fabricating and/or assembling a spark plug insulator assembly, which includes an induction heating apparatus disclosed herein and other components such as, e.g., an auxiliary unit and a control unit, to automate and accelerate the manufacturing process.

A method for manufacturing a spark plug. The method includes: furnishing an insulator; introducing into the insulator a material mixture that is configured to constitute a resistor paste, the material mixture containing ZrO.sub.2 and SiO.sub.2; heating the insulator and the material mixture present therein to a temperature T of at least 870° C., so that ZrO.sub.2 and SiO.sub.2 in the material mixture react at least partly to ZrSiO.sub.4.

A method for manufacturing a spark plug. The method includes: furnishing an insulator; introducing into the insulator a material mixture that is configured to constitute a resistor paste, the material mixture containing ZrO.sub.2 and SiO.sub.2; heating the insulator and the material mixture present therein to a temperature T of at least 870° C., so that ZrO.sub.2 and SiO.sub.2 in the material mixture react at least partly to ZrSiO.sub.4.

A spark plug connecting element. The spark plug connecting element includes a first contact element and a second contact element. A resistor element is situated between the first contact element and the second contact element. The first contact element and the second contact element have a specific conductivity of 10.sup.2 S/m to 10.sup.8 S/m and the resistor element has a specific conductivity of 10.sup.−3 S/m to 10.sup.1 S/m.