Ngk Spark Plug Company, Limited

Noboru Aoki

Takahiro Suzuki

Yuki Izuoka

Shuzo Matsumura

Takanori Mizuno

Takahire Suzuki

An igniter plug has a tubular metallic shell and an annular ground electrode each connected in series by an interfitting, and fixed by welding. The igniter plug further has a tubular insulator placed within both the metallic shell and the ground electrode, while a center electrode is placed within the insulator to be surrounded by the ground electrode. A plurality of lock arms are provided with a front end of the metallic shell, and each top end of lock arms has a pawl which is brought into an engagement with an inner wall of a groove which is provided with an inner surface of the ground electrode when the metallic shell and the ground electrode are connected, and at the same time, the insulator is brought into an engagement with an inner side of each lock arm to deter the lock arms from being flexed inwardly when the insulator is placed.

Igniter plug

An igniter plug is provided with a metallic shell, an insulator located within the metallic shell and a center electrode within the inner bore of the insulator. The front end of the electrode extends outside beyond the front end of the insulator. The insulator is made from sintered ceramic material which includes silicon nitride in an amount in the range 85-99% by weight. The front end of the insulator is axially retracted interiorally from the front end of the metallic shell from about 1.5 to about 2.5 mm.

Igniter plug particularly for use in very low temperature liquid fuel

A low-voltage type igniter plug having semi-conductor structure for use in jet and other internal combustion engines comprising; the semi-conducting body mounted adjacent a spark-gap in electrically contact with both center and ground electrodes, and essentially consisting of silicon carbide particles less than 5 microns in average diameter, and alumina particles less than 1 micron in average diameter, the weight percentages of the silicon carbide particles ranging from 65 to 80, the weight percentages of the alumina particles ranging from 20 to 35, the silicon carbide particles and the alumina particles being mixed with an addition of suitable binder means, and hot pressed at the temperature above 1800 degrees Celsius, and at the pressure above 200 Kg/cm.sup.2.

Low-voltage type igniter plug having semi-conductor structure for use in

This invention provides an igniter plug, having a plurality of grooves within an outer surface of an annular ground electrode (2), the diameter of which is reduced to about 13 mm. Each groove (6) generally has a semi-circular shape in cross section to allow air flow along the grooves (6), with the number of the grooves (6) in the range from 4 to 16, and the width of each groove is to about 1.0 mm to 2.5 mm. The semi-circular cross section of the grooves (6) makes it possible to provide a large surface for the grooves without increasing the amount of machining, thus, enhancing cooling efficiency when the air flows along the grooves.

Igniter plug structure having semicircular grooves

This invention provides a creeping discharge type igniter plug, having a center electrode concentrically located within the center bore of the insulator. Near the lower portion of the center electrode is an annular space (6), formed between an outer surface of the center electrode and an inner surface of the semi-conductor ring (4). At the annular space (6), a lateral distance between the outer surface of the center electrode (2) and the inner surface of the semi-conductor ring (4), progressively decreases toward a lower end of the semi-conductor ring (4) thus, making it possible to maintain the least electrical resistance at a creeping discharge path defined from a lower end surface (3a) of the ground electrode (3) to a lower end surface (2a) of the center electrode (2) via a lower end surface (4b) of the semi-conductor ring (4).

Creeping discharge type igniter plug

An igniter plug comprising: a metallic shell having a diameter-reduced seat at one open end, the seat being tapered to progressively decrease its diameter as approaching at outside of the open end; a tubular insulator concentrically placed at an inner side of the metallic shell, and having a tapered end face to be in registration with the seat; a frusto-cone shaped insert ring made of oxidation and heat resistant material, a peripheral end and one entire surface of which are mounted on a surface of the seat by means of an electrical resistant welding, the insert ring permitting the tapered end face of the insulator to engage with an upper surface of the insert ring; a center electrode concentrically disposed in the insulator, one end of the electrode being terminated short of the tapered end face to allow a creeping discharge to occur along an inner surface of the insulator when a high voltage is applied across the electrode and the insert ring.

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Nagoya, Japan

Noboru Aoki