Abstract: An igniter plug is disclosed for use in jet and other internal combustion engines. The igniter plug has a center electrode having a firing tip, which is mounted within an insulator which in turn is mounted within an exterior metal shell. A ground electrode is integral with or in electrical contact relationship with the metal shell and is disposed in a spaced, spark gap relation with the firing tip of the center electrode. An electrically semiconducting surface is disposed adjacent the spark gap and in electrical contact with the center electrode and with the ground electrode. The electrically semiconducting surface is formed by a sintered ceramic body having an actual density of more than 95 percent of its theoretical maximum density, and consists essentially of 67-80 wt % of silicon carbide particles and 20-33 percent by weight of grain boundary phase of alumina particles, as well as one or more sintering aids selected from magnesia, silica or calcia.

Abstract: A spark plug in use for an internal combustion engine, includes an insulator placed in a metal shell in a manner to extend its front end beyond the metal shell, a center electrode is placed within an axial bore provided by the insulator, an outer electrode which is welded to a front end of the metal shell is so bent that a firing end of the outer electrode faces a front end of the insulator with a space therebetween to cause surface-spark discharges along a front end surface of the insulator and to cause a semi-surface spark discharge between the center electrode and the outer electrode, the front end of the center electrode is protroacted from a front end of the insulator by at most than 0.5 mm or retracted from the front end of the insulator by at most than 1.0 mm, and the firing end of the outer electrode is in line with the front end surface of the insulator, thereby optimizing a carbon-deposit cleaning performance of the spark plug with the semi-surface spark discharge, according to the invention.

Abstract: A spark plug (10), for example for an internal combustion engine, having at least one center electrode (11) (high-voltage electrode) and at least one earth electrode (12), and an insulating spark plug insulator (13) and a creepage spark gap (14) between the center electrode (11) and the earth electrode (12). The creepage spark gap (14) has a pattern of islands comprising electrically-conductive material (16) which are insulated with respect to one another and are located on the outer surface zone of the spark plug insulator (13) or on the surface zone of an insulating material wafer (17) attached to outer surface of the insulator (13) of the spark plug (10).

Abstract: A spark plug for igniting fuel/air mixtures in internal combustion engines, in particular in internal combustion engines of motor vehicles. On its insulating-body foot, the spark plug has a coating which is intended to protect against misfirings and cold-starting difficulties as a consequence of electrically conductive deposits, in particular in the case of installation of spark plugs in new motor vehicles. The coating includes solvent-free silicone rubber or silicone resin. The silicone rubber may contain filler and is provided with silicone oil for the purpose of good processability. Expediently, the inner side of the metal housing which is exposed to the combustion chamber is also covered with the coating. The coating is physiologically safe, environmentally acceptable and resistant to handling, and does not require expensive extraction systems if it is sprayed onto the appropriate region of the spark plug by means of nozzles.

Abstract: A Double Sliding Spark Plug as a Volume Ignition System for Internal Combustion Engines causes ignition processes of the air-fuel mixture by two simultaneously conical or cylindrical sliding discharges between a conical or cylindrical high voltage electrode (1) located inside two solid insulation parts (4) and (5) and two circular low voltage electrodes (2) and (3). Those sliding discharges are on outer large conical or cylindrical surfaces of insulation parts (4) and (5) with high diameters. The outside low voltage electrode (2) is connected to a metallic body of this spark plug and to the outer conical or cylindrical surface of the outside insulation part (4). The inside cylindrical or conical low voltage electrode (3) is connected to the inner conical or cylindrical surface of the inside insulation part (5).

Abstract: A volume ignition system for internal combustion engines causes ignition processes of fuel by location of a high voltage electrode (1) of a spark plug inside an engine's cylinder. Electrical discharges are created basically from the high voltage electrode (1), during movement of a piston (6) with a connected ring (5), as low voltage electrodes, around the high voltage electrode (1), and to a low voltage electrode (2), connected to the spark plug's metallic body, as sliding discharges. Sliding discharges are created over an insulator (3) along metallization (4), with an extremely large surface area. Discharge plasma is injected into a combustion chamber with flames from inside of the ring (5) and a hollow (7).

Abstract: An improved low voltage igniter of the type having an annular spark gap between a center electrode and annular ground electrode which is arranged coaxial with the center electrode. The spark gap is shunted by an insulator surface. Semiconducting material is deposited on the insulator surface as one or more rings which are coaxial with and spaced from the electrodes. The semiconducting rings reduce the voltage required to initiate a spark across the spark gap.

Abstract: An igniter plug has a metallic shell, a front end of which has a tubular ground electrode. A hollow semiconductor tip is in the form of inversed frusto-cone shape, and placed within the tubular ground electrode. A tubular insulator is placed within the metallic shell to be in alignment with the semiconductor tip. A center electrode is placed within the insulator, a front end of the center electrode passing through the semiconductor tip to provide an annular discharge gap between the front end of the center electrode and that of the ground electrode. A low resistor layer provided on a front end surface of the semiconductor tip. An electrical resistance of the layer is determined to be smaller than that of the semiconductor tip, while a thickness of the layer is such that the layer precedes the semiconductor tip in forming a discharge path between the front end of the center electrode and that of the ground electrode only during a predetermined period after the igniter plug is initially operated.

Abstract: 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.

Abstract: A spark plug with combined surface discharge and air discharge gaps, wherein a central electrode (3), an insulator (2) surrounding the central electrode, and a ground electrode (4) surrounding the insulator (2) together with a spark plug body (1) are provided. The insulator (2) forms at its end portion a discharge chamber (5) through which the central electrode (3) extends axially as far as the end portion of the spark plug body (1). The earth electrode surrounds the insulator (2) around its end with a projection extending into the discharge chamber (5).

Abstract: 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.

Abstract: A wear indicator for an igniter of the type having a center electrode, an annular ground electrode surrounding the center electrode, and a spark gap between the electrodes extending along a surface of a ceramic material. An annular wear indicating groove is formed in the ground electrode to indicate when the ground electrode is sufficiently eroded to necessitate replacement of the igniter. For a low voltage igniter the ceramic material at the spark gap is a semiconductor material which also is subject to erosion during use. A wear indicating groove also may be formed on the center electrode at a location which becomes exposed to indicate when the semiconductor material is sufficiently eroded to necessitate replacement of the igniter.

Abstract: A spark plug for internal combustion engines comprises a center electrode enclosed in an insulating body enclosed in a metal housing, and a ground electrode. The insulating body has an end portion which faces the combustion chamber. An electrical field develops, resulting in a surface spark gap between two electrodes on the surface of the insulating body at the end portion thereof. The insulating body is transversely divided into the upper portion and the lower portion, of which the lower portion facing the combustion chamber is made of a material having dielectric constant 5-50 times higher than that of the upper portion.

Abstract: In a spark plug with combined surface and air spark paths comprising a center electrode, and insulator which surrounds the center electrode and which, at least in the end region of the center electrode, maintains a gap with respect thereto, and a ground electrode which, together with the spark plug body, surrounds the insulator and which at least in the end region of the insulator maintains a gap with respect thereto, the insulator, to form a discharge chamber surrounding the end portion of the center electrode, extends in the axial direction of the plug beyond the center electrode, and the ground electrode encompasses the insulator around the end thereof with an extension of the ground electrode extending into the discharge chamber with a clearance gap being maintained between the extension and the end portion of the insulator.

Abstract: A surface-discharge igniter for a gas-turbine engine has a pellet of rod shape a part at least of the pellet surface being semiconductive so that when voltage is applied between electrodes connected at either end of the pellet it causes electrical discharge along its length. The pellet may, in one arrangement, be mounted to be a tight fit within the central-section of a key-hole bore which extends axially through a ceramic block within the igniter's outer metal shell. A strip of the pellet surface is exposed along the radially-divergent section or discharge cavity of the bore and discharge along the strip generates a plasma flame within the cavity that bursts forth through an aperture in the bottom electrode at the tip of the shell. In another arrangement the rod-pellet is mounted at the end of a mineral-insulated cable, coaxially within a cylindrical cavity. The pellet may alternatively be mounted to extend transversely of the igniter and to be exposed along its length at the operative tip of the igniter.

Abstract: A long distance discharge gap type spark plug comprising a center electrode, a porcelain insulator surrounding the center electrode and provided at its lower side with a firing portion made integral therewith and composed of a reduced diameter trunk wall, and a grounded electrode is disclosed. The spark plug comprises a surface gap L formed between the front end of the center electrode and the grounded electrode, a minor air gap l formed between the outer peripheral surface of the firing portion and the grounded electrode and a thickness t of the trunk wall of the firing portion and given by1.0 mm .ltoreq. L .ltoreq. 4.5 mm,0 .ltoreq. l .ltoreq. 0.6 mm and0.5 mm .ltoreq. t .ltoreq. 0.9 mm,Respectively, the surface gap L being determined within a range that satisfies the following conditionsL .ltoreq. 5 t + 2.0 mm when 0.4 mm < l .ltoreq. 0.6 mm,L .ltoreq. 5 t when 0.2 mm < l .ltoreq. 0.4 mm,L .ltoreq. 5 t - 1.5 mm when 0 < l .ltoreq. 0.2 mm, andL .ltoreq. 5 t - 2.5 mm when l = 0.

Abstract: A spark plug wherein corona discharge is employed to create a long arc and to determine, in part, the path of the arc, electrodes of the spark plug being shaped, oriented and positioned to create an arc of desired length and at a desired location as well as to effect electromagnetic interaction between electric current in the arc and the electrodes to provide a force on the arc which acts to control its spatial behavior. The spark plug includes means to enhance the electromagnetic interaction.