A spark gap assembly includes a sealed chamber, at least two discharge electrodes, and a non-radioactive gas fill within the sealed chamber. The sealed chamber includes first and second end plugs and a vitreous tube having opposite ends, each end being sealed by one of said end plugs. The discharge electrodes extend through the first and second end plugs, respectively, from an exposed portion outside of the sealed chamber to an enclosed portion inside the sealed chamber. The discharge electrodes each have a discharge portion that includes a surface from which electrons of a spark discharge exit or are received, with the discharge surfaces of the discharge portions facing each other to thereby define a spark discharge gap between the discharge surfaces of the two discharge electrodes. The gas fill within the sealed chamber includes one or more non-radioactive isotopes of one or more noble gases.

An ignition apparatus for an internal combustion engine which is capable of having a high-degree of ignition performance and being reduced in size is provided. The ignition apparatus includes the spark plug mounted in an end of the plug hole formed in the internal combustion engine, the first ignition coil, the second ignition coil, and the control portion. The first ignition coil includes the primary coil and the secondary coil and has a secondary side electrically connected to the spark plug. The second ignition coil includes the primary coil and the secondary coil and is connected to the spark plug in parallel to the first ignition coil. The control portion controls energization of the first ignition coil and the second ignition coil. The secondary voltage developed at the second ignition coil is lower in level than that developed at the first ignition coil. The control portion works to create the secondary voltage at the first ignition coil and then create the secondary voltage at the second ignition coil to have the spark plug continue to discharge.

A problem exists in that, as a loop through which high frequency energy conducts is long, it is difficult to suppress noise generated from the loop and suppress an influence thereof on peripheral equipment. A high frequency discharge ignition device according to this invention is a structure integrally constituted by a second housing into which a high frequency energy supply circuit is built and a first housing into which an output circuit is built, wherein the high frequency energy supply circuit is connected to the output circuit by a connection terminal so as to be connected to a spark plug which is mounted on a grounded object. Further, the high frequency energy supply circuit is grounded via a conducting member disposed in a through hole provided in the first housing.

A problem exists in that, as a loop through which high frequency energy conducts is long, it is difficult to suppress noise generated from the loop and suppress an influence thereof on peripheral equipment. A high frequency discharge ignition device according to this invention is a structure integrally constituted by a second housing into which a high frequency energy supply circuit is built and a first housing into which an output circuit is built, wherein the high frequency energy supply circuit is connected to the output circuit by a connection terminal so as to be connected to a spark plug which is mounted on a grounded object. Further, the high frequency energy supply circuit is grounded via a conducting member disposed in a through hole provided in the first housing.

A spark plug having a center electrode that is formed by joining a conductive portion made of a conductive material and an insulating portion made of an insulating material. A sealing member electrically connects the conductive portion to a resistor. The insulating portion includes a protruding portion at a location on the back side of a back end of the sealing member. The protruding portion is embedded in the resistor.

A connection structure between a center electrode and a metal terminal of a spark plug having a composite part that contains a plurality of secondary particles each formed of a plurality of primary particles of iron-containing oxide as a magnetic substance, and a conductive material coating the plurality of secondary particles. The iron-containing oxide includes at least one of an oxide represented by M.sub.1+AOFe.sub.2AO.sub.3 (where 0.5A0.5; and M is at least one kind of element selected from the group consisting of Mn, Fe, Co, Ni, Cu, Mg, Zn and Ca) and an oxide represented by Q.sub.3Fe.sub.5O.sub.12 (where Q is at least one kind of element selected from the group consisting of Y, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd and Sm). In cross section, an average particle size of the primary particles is 0.5 m to 100 m, an average particle size of the secondary particles is 0.5 mm to 2.0 mm, and a porosity of the inside of the secondary particles is 5% or lower.

A connection structure between a center electrode and a metal terminal of a spark plug having a composite part that contains a plurality of secondary particles each formed of a plurality of primary particles of iron-containing oxide as a magnetic substance, and a conductive material coating the plurality of secondary particles. The iron-containing oxide includes at least one of an oxide represented by M.sub.1+AOFe.sub.2AO.sub.3 (where 0.5A0.5; and M is at least one kind of element selected from the group consisting of Mn, Fe, Co, Ni, Cu, Mg, Zn and Ca) and an oxide represented by Q.sub.3Fe.sub.5O.sub.12 (where Q is at least one kind of element selected from the group consisting of Y, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd and Sm). In cross section, an average particle size of the primary particles is 0.5 m to 100 m, an average particle size of the secondary particles is 0.5 mm to 2.0 mm, and a porosity of the inside of the secondary particles is 5% or lower.

An ignition coil for internal combustion engines is provided which includes a primary and a secondary coils magnetically coupled with each other, a case, a resistor, and a resinous filler. The case includes a case body in which the primary and secondary coils are disposed and a tubular high-voltage tower extending from the case body toward a head of the ignition coil. The resistor 3 is press-fitted into the high-voltage tower and electrically connected to the secondary coil. The resinous filler is packed in the case body to hermetically seal the primary coil and the secondary coil. The resistor includes a resinous coating which covers an outer circumference of the resistor and is press-fit in the high-voltage tower through the resinous coating. This facilitates hermetically sealing a gap between the resistor body and the case and ensures the stability of the sealing.

Described is a spark plug connector having an interference-suppression resistor which has a wire winding on a coil body. According to this disclosure, it is provided that the coil body carries an electrical resistor that contacts the wire winding and is connected in parallel thereto. In addition, an interference-suppression resistor for an ignition system of an internal combustion engine is described.

Described is a spark plug connector having an interference-suppression resistor which has a wire winding on a coil body. According to this disclosure, it is provided that the coil body carries an electrical resistor that contacts the wire winding and is connected in parallel thereto. In addition, an interference-suppression resistor for an ignition system of an internal combustion engine is described.