Abstract: A pre-chamber spark plug that includes a shell, and an end cap attached to the shell. Additionally, the pre-chamber spark plug includes an insulator disposed within the shell. In a particular embodiment, a center electrode has a first portion surrounded by the insulator, and a second portion that extends from the insulator into a pre-chamber. The pre-chamber defined by the shell and end cap. In a further embodiment, a ground electrode is attached to the shell. In particular embodiments, the ground electrode is tubular in shape and includes an inner spark surface ring spaced in surrounding relation to the center electrode to create a spark gap, an outer ring attached to the shell, and a plurality of rounded spokes connecting the inner and outer rings. In a particular embodiment, the ground and center electrodes accommodate attachment of precious metal alloys to increase electrode surface life.

Abstract: A spark plug is described as including an insulator which is situated in a spark plug housing and which has a longitudinal axis and an opening along the longitudinal axis. Furthermore, a center electrode is situated in the opening of the insulator. Furthermore, at least one ground electrode is provided at the spark plug housing. The insulator has a first insulator section and a second insulator section, the first insulator section extending in the direction of the longitudinal axis over a first insulator section length having a first inner diameter. The second insulator section extends in the direction of the longitudinal axis over a second insulator section length having a second inner diameter. Here, the first inner diameter is smaller than the second inner diameter, the first insulator section merging directly into the second insulator section.

Abstract: The present teachings provide for a spark plug for an internal combustion engine and a method of constructing the spark plug. The spark plug can include a housing, insulator, first electrode, and ground electrode. The housing can be configured to be coupled to the engine. The insulator can be received in the housing. The first electrode can be received in the housing and can be spaced apart from the housing by the insulator. The ground electrode can have a first end, second end, and base portion. The first and second ends can be coupled to the housing for thermal conduction with the housing. At least one of the first and second ends can be coupled to the housing for electrical conduction with the housing. The base portion can be spaced apart from the first electrode to define a spark plug gap between the first electrode and the base portion.

Abstract: A spark plug for a stationary, gas-powered internal combustion engine, having a metallic body, an insulator mounted in a passage of the body, a center electrode passing through the insulator, a ground electrode mounted on the body that, together with the center electrode, forms a spark air gap, and a cap attached to the body. The cap shields the center and ground electrodes from the combustion chamber after the spark plug is installed in a combustion chamber of the internal combustion engine, and that, together with the body of the spark plug, forms a prechamber in which the center and ground electrodes are located. The cap has at least one opening that permits gas exchange between the prechamber and the space outside of the prechamber.

Abstract: A radiation device and related method are presented. The radiation device includes a body. The body includes a threaded portion configured to engage with a threaded opening in an engine and an open interior volume. The radiation device includes a ground electrode coupled to the body, a substrate disposed within the open interior volume in the body, and a radio frequency generator on the substrate. The radio frequency generator is configured to receive an input signal and, in response to the input signal, generate plasma energy between the body and the ground electrode.

Abstract: A spark plug, and associated systems, for an internal combustion engine includes a central electrode that terminates at a first distal end surface defined about a central axis. The spark plug also includes at least one outer electrode that terminates at a second distal end surface. The at least one outer electrode at least partially laterally surrounds the central electrode such that the second distal end surface is radially offset relative to the central electrode and a lateral gap is defined between the central electrode and the at least one outer electrode. The spark plug include features that force or redirect movement of the flow of the fresh air-fuel mixture through the lateral gap to help to purge or move the residual exhaust gases left over from a previous combustion event out of the lateral gap.

Abstract: A spark plug includes an insulator and a metal shell arranged around the insulator and having a thread portion formed with a thread diameter of M12. The insulator has an engagement portion held on a step portion of the metal shell via a plate packing and a leg portion located to leave a clearance between the leg portion and an inner circumferential surface of the metal shell. Assuming that: L (mm) is a distance from a front end of the plate packing toward the front; and A (mm) is a size of the clearance, a site of the clearance where the size A becomes 0.5 mm or smaller is located at or rear of a position of 2.0 mm from the front end toward the front; and a relationship of A?L×0.2+0.2 (mm) is satisfied within a range of 3.0?L?4.0.

Abstract: The plug comprises a nut, a coupling extending from the nut and adapted to receive an ignition wire and an insulator extending from the nut and away from the coupling. A positive electrode extends through the insulator. An externally-threaded tubular portion extends from the nut in surrounding relation to the insulator and terminating, short of the insulator end, in a cap that is disposed in spaced relation to the insulator. The cap defines a void having: a central portion into which the positive electrode extends; an annular channel surrounding the central portion; and a plurality of lobes, each positioned with respect to the central portion as the planet gears are positioned with respect to the sun gear in a planetary gear. The cap has a central surface that is axially spaced from the insulator and a convex surface that surrounds and extends to the central surface.

Abstract: A spark plug in which a front end portion of a ground electrode is positioned outside of a virtual outer circumferential face that is formed by extending a front and outer circumferential face of a center electrode in the axis direction, and positioned on a front end side in the axis direction with respect to a virtual face including a front end face of the center electrode. Further, the equation 1.1?b/a?1.6 is satisfied, where “a” (mm) represents a first minimal distance between the front end portion of the center electrode and the front end portion of the ground electrode and, where “b” (mm) represents a second minimal distance between the front end portion of a ceramic insulator and the front end portion of the ground electrode.

Abstract: A spark plug includes a center electrode having an end portion, and an earth electrode having an opposing portion opposed to the end portion via a gap. The end portion has an end-projecting portion. The opposing portion has an opposing-projecting portion opposed to the end-projecting portion. The end-projecting portion and the opposing-projecting portion have non-projection direction opposing surfaces which are parallel to and opposed to each other with a minimum distance and in a direction other than a projection direction. A first opposing area of a portion which includes the non-projection direction opposing surfaces and where the end-projecting portion and the opposing-projecting portion are opposed to each other with the minimum distance is larger than a second opposing area obtained when a plane of the end-projecting portion and a plane of the opposing-projecting portion, which are orthogonal to the projection direction, are opposed to each other in the projection direction.

Abstract: A spark plug includes an insulator having a first end, the insulator having a center axis and a center electrode coupled to the insulator and having a center electrode tip extending beyond the first end of the insulator. The spark plug further includes a ground electrode having an end spaced from an end of the center electrode, the ground electrode having a first portion extending substantially parallel to the center axis and a second portion extending at an angle from the first portion and relative to the center axis. A ground electrode tip is disposed on the second portion of the ground electrode, wherein the ground electrode tip is spaced from the center electrode tip. A ring member is operatively connected to the center electrode proximate the center electrode tip.

Abstract: A corona igniter 20 includes a central electrode 34 for receiving a high radio frequency voltage from a power source and emitting a radio frequency electric field to ionize a fuel-air mixture and provide a corona discharge 22. The corona igniter 20 includes an insulator 38 extending along the central electrode 34 longitudinally past the central electrode 34 to an insulator firing end 40. The insulator firing surface 42 and the center axis A present an angle ? of not greater than 90 degrees therebetween, for example the insulator firing surface may be concave. The central electrode 34 may also include a firing tip 50, in which case the insulator firing surface 42 surrounds all sides of the firing tip 50. The geometry of the insulator firing surface 42 concentrates and directs the corona discharge 22.

Abstract: In some aspects, a spark plug includes a spark gap in an enclosure of the spark plug. The spark plug includes a passage in the interior of the enclosure. During operation of the engine, the passage directs flow through the spark gap, primarily away from a combustion chamber end of the enclosure. The passage can direct flow at a velocity of 5 meters/second or greater.

Abstract: A plasma jet ignition plug exhibiting high plasma generation efficiency while restraining occurrence of preignition. P1 represents the position of a rear end of a region of a metallic shell ledge, the region being in contact with an insulator. P2 represents the position of a rear end of a region of the insulator ledge, the region being in contact with the center electrode. Front end surfaces of the metallic shell, the insulator, and center electrode, an imaginary plane S1 which is perpendicular to the axis and contains position P1, and an imaginary plane perpendicular to the axis and contains position P2 are disposed in this order from front side to rear side along the axis. The axial distance A from the front end surface of the insulator to imaginary plane S1 and axial distance B from the imaginary plane S1 to imaginary plane S2 satisfy 0.5×A?B.

Abstract: A spark plug electrode material that may be used in spark plugs and other ignition devices including industrial plugs, aviation igniters, glow plugs, or any other device that is used to ignite an air/fuel mixture in an engine. According to an exemplary embodiment, the electrode material includes a refractory metal (for example, tungsten (W), molybdenum (Mo), rhenium (Re), ruthenium (Ru) and/or chromium (Cr)) and a precious metal (for example, rhodium (Rh), platinum (Pt), palladium (Pd) and/or iridium (Ir)), where the refractory metal is present in an amount that is greater than that of the precious metal. This includes, but is certainly not limited to, electrode materials including tungsten-based alloys such as W—Rh and ruthenium-based alloys such as Ru—Rh. Other combinations and embodiments are also possible.

Abstract: A plasma ignition system includes an ignition plug attached to an engine and a high-voltage supply. The plug includes a center electrode serving as a positive pole, a ground electrode serving as a negative pole, and an insulating member insulating the center electrode from the ground electrode and defining a discharge space therein. At least a part of a surface of the center electrode faces the space, and at least a part of a surface of the ground electrode faces the discharge space. The plug puts gas in the space into a plasma state and injects the gas into the engine as a result of application of high voltage and supply of a large current to the plug by the high-voltage supply. The center electrode has a recess portion opposed to the space and recessed in a direction opposite to an injection direction.

Abstract: A spark plug is provided, for a provisional bending process for manufacturing the spark plug, as a work in a condition where an earth electrode is straight and substantially in parallel with an axial line of a center electrode. In the provisional bending process, two searchers individually facing the tip of the center electrode with the tip located therebetween are arranged, positions of the searchers in a first direction perpendicular to the axial line being adjusted for every spark plug. Then a bending punch is driven to press a second end-surface of the other end of the earth electrode down to the searchers so that the earth electrode is provisionally bent at a substantially perpendicular angle to the axial line, the second end-surface being opposite to the first end-surface. Preferably, before the provisional bending process, positioning the work and correcting the position and tilt of the work are performed.

Abstract: Ir alloy firing tips are bonded on opposed surfaces of a center electrode and a ground electrode facing to a discharge gap. The configuration of a cross-sectional area of the Ir alloy firing tip taken along a plane perpendicular to the axis of the Ir alloy firing tip is out of round. In this cross-sectional area of this Ir alloy firing tip, when it is assumed that a circumscribed circle has a largest diameter A among virtual circles each contacting at least three portions of a visible outline of the cross-sectional area and an inscribed circle has a largest diameter B among inscribed circles each being coaxial with the circumscribed circle, a ratio of the diameter B to the diameter A (i.e., B/A) is equal to or larger than 0.8 and is less than 1.0.

Abstract: In a spark plug, a cylindrical metal shell (1) is provided whose inner wall has a rear section and a front section to respectively serve as a diameter-increased section and a diameter-decreased section with a seat portion (1) as a boundary therebetween. An insulator (2) is fixedly placed within the metal shell (1) so that a front end surface (21) of the insulator (2) extends beyond a front end surface (12) of the metal shell (1) with a shoulder portion (231) of an insulator nose (23) engaged against the seat portion (11) of the metal shell (1) by way of a packing (10). A center electrode (3) is fixedly placed within an axial bore (22) of the insulator (2), A ground electrode (4) is connected to the front end surface (12) of the metal shell (1), and bent so that a front end surface (41) of the ground electrode (4) opposes an outer surface (311) of the center electrode (3).

Abstract: A spark plug, especially one for a gas-fueled internal combustion engine has an electrically conducting spark plug body (1), a central electrode (3) which is located in the spark plug body (1) and which is electrically insulated from and projects away from the spark plug body (1), and a ground electrode (4) which is electrically connected to the spark plug body (1) and is made in the form of an annular electrode. The annular electrode (4) surrounds the front part of central electrode (3) such that an annular ignition gap (ZS) is formed between them. Surfaces of the central electrode (3) and the annular electrode (4) bordering the ignition gap (ZS) are provided with precious metal armorings in the form of sleeves (5, 6,), especially of platinum or a platinum alloy. This yields a spark plug with an extremely long service life.

Abstract: A very unique universal bi-directional firing spark plug for any spark ignited internal combustion engine, whether racing, industrial, truck, aeronautical, automotive, recreational or residential (for trimmers, edgers, brush cutters, leaf blowers, leaf vacuums, chain saws, augers, tillers, lawnmowers, riding mowers, tractors, generators, etc.). This spark plug eliminates misfire and improves gas mileage, peaks engine performance, horsepower, and increases the RPM range, while utilizing and enhancing current ignition systems. In addition, this spark plug serves as a low emission device that reduces the effects of global warming, acid rain, and smog via greatly reduced emissions through vastly improved fuel combustion within all internal combustion engines by operating at a 24:1 air-to-fuel ratio. This unique spark plug is comprised of an elongated or non-elongated body with an electrical connector at one end.

Abstract: A very unique universal bi-directional firing spark plug for any spark-ignited internal combustion engine is described. This spark plug eliminates misfire and improves gas mileage, peaks engine performance, horsepower, and increases the RPM range. This unique spark plug is made of an elongated or non-elongated body with an electrical connector at one end. An absolute aerodynamic semispherical dome or sphere electrode is secured to the other end of the body. At least one absolute aerodynamic semicircular electrode is also secured to the body adjacent to the dome or sphere electrode such that the semicircular electrode has its inner surface equidistantly spaced from the dome or sphere electrode's surface. The electrodes can be fabricated from various metals, alloys, and/or precious metals and can also be coated with various metals, alloys, and/or precious metals.

Abstract: An electrode assembly having a structure which minimizes stress cracks within its outer housing is disclosed. The outer housing is comprised of a ceramic tube having a bore therethrough which is coated with an epoxy material. An insulated electrical conductor with the wires contained therein in an exposed condition adjacent the end thereof is received in one end of the tube and is slidably advanced within the bore to the approximate midpoint of the tube. An electrode member is received in the opposite end of the tube and is slidably advanced within the bore so that its end contacts the exposed wires of the electrical conductor causing the ends of the wires to flare outwardly and grippingly engage the surface defining the bore in the tube. Subsequent heating of the electrode assembly causes the epoxy within the bore of the tube to bind the tube to the electrode member, the exposed wires and the insulated portion of the electrical conductor resulting in a solid, unitary construction for the electrode assembly.

Abstract: A novel spark plug with an outer annular electrode and an inner electrode includes a disk-shaped element supported atop the inner electrode. The gap between the outer electrode and the disk-shaped element of the inner electrode defines an annular firing zone within which the spark travels from the outer electrode to the inner electrode. The disk-shaped inner electrode is solid and planar, and overlies the outer electrode. The disk may be provided with a lip of hardened alloy material which extends in the direction of the outer electrode. The lip can have a rectangular cross-section or a triangular cross-section, and the gap between the inner and outer electrodes can be adjusted, either at the time of assembly or later.

Abstract: A spark plug for an internal combustion engine which has an electrode centrally mounted within an insulator with this insulator being mounted within an elongated housing. The outer end of the insulator is formed into a core nose with this core nose either being planar or mounded. Located directly adjacent the core nose and spaced slightly therefrom plus being spaced from the electrode is a ground ring. The electrical resistance is selected so that the spark will travel from the center electrode across the core nose and then jump the air gap at approximately the closest spacing distance from the ground ring and the core nose. The ground ring can be ported. The ground ring annular opening into the fire hole of the spark plug may be sawtoothed to form a mass of spark-emanating points.

Abstract: A spark ignition system and spark plug for utilization in an internal combustion engine combusting an ultra lean fuel/air mixture has capacitors and rectifiers built within the spark plug and the system is constructed to be compact and capable of delivering a controlled spark that has the physical properties of providing a very fast, high power pulse or train of pulses greater than conventional spark plugs.

Abstract: A large discharge-volume spark plug for providing self-limiting microdischarges. The apparatus includes a generally spark plug-shaped arrangement of a pair of electrodes, where either of the two coaxial electrodes is substantially shielded by a dielectric barrier from a direct discharge from the other electrode, the unshielded electrode and the dielectric barrier forming an annular volume in which self-terminating microdischarges occur when alternating high voltage is applied to the center electrode. The large area over which the discharges occur, and the large number of possible discharges within the period of an engine cycle, make the present silent discharge plasma spark plug suitable for use as an ignition source for engines. In the situation, where a single discharge is effective in causing ignition of the combustible gases, a conventional single-polarity, single-pulse, spark plug voltage supply may be used.

Abstract: A high power high energy ignition system for internal combustion engines using an energy storage capacitor (4), resonating inductor (3) and one or more coils Ti with switches Si for each coil Ti. The system is designed and optimized according to the transient voltage doubling formulation and certain coil magnetic flux formulations to produce a very high power, very high energy, high efficiency ignition powered and controlled by a power converter (14) and controller (15) to produce an initial high frequency spark pulse followed by moderate firing longer duration spark pulses or continuously firing spark oscillations for delivery to the air-fuel mixture of an engine with total spark energy approximately independent of engine speed. The energy is delivered by means of a toroidal gapped spark plug (46) with extended electrodes (48a) to maximize ignition kernel size and minimize spark plug erosion and fouling.

Abstract: 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.

Abstract: The gas discharge space into which microwaves are fed via a waveguide forms a laser housing in the form of a waveguide having a longitudinal ridge therein, the laser housing being preferably dimensioned such that its critical wavelength .lambda..sub.k is shorter than or equal to the wavelength .lambda..sub.o of the microwave frequency. The gas laser may advantageously be a CO.sub.2 gas laser.

Abstract: An electrical igniter has an outer metal shell within which extends a semiconductive tubular pellet that provides a cylindrical cavity which opens through an orifice formed by an inturned lip of the shell which forms a first electrode of the igniter. The diameter of the cavity and the diameter of the orifice are in the ratio of about 5 to 6. A second electrode extends axially within the shell into the rear end of the pellet with which it makes electrical contact. Discharge between the first and second electrodes causes a plasma of discharge products produced in the cavity to be ejected through the orifice.

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: In order to prevent, in the microwave excitation of a laser gas, the development of wall boundary layers and to attain a homogeneously large volume plasma, the laser gas is delivered in the inclusion zone of the microwave after passing a current-forming element where it is ignited by a coaxial wave guide arrangement. The ignited laser gas then spreads with the microwave in the discharge segment where it produces a homogeneous, excited laser-active medium. The homogeneity is additionally improved with the operation of the microwave guide near the "cutoff-width".

Abstract: A small-sized spark plug for internal combustion engines is disclosed which is composed of a center electrode having a shaft portion surrounded by an insulator layer and a terminal end portion adapted to act as a spark generation portion; and an earthed electrode having a terminal end portion which is spaced apart from and is opposite to the terminal end portion of the center electrode so that a spark gap is defined along a surface of the insulator layer. The shortest distance .delta. (mm) between each end portion of the two electrodes and the surface of the insulation layer and the distance l between the forward end portions of the two electrodes have the following relationship:.delta..gtoreq.0.25 l, and 0.8 mm.ltoreq.l.ltoreq.2.0 mm.A recessed portion may be provided on the surface of the insulation layer.

Abstract: A system for initiating combustion of fuel, especially for internal combustion engines, employs a very rapid, intense high power electrical breakdown arc to increase the rate of combustion and thereby reduce the need for advanced engine timing. The use of a distribution circuit which has exceptionally low inductance and resistance results in the rapid electrical breakdown and coupling of at least 80% of stored pulse energy to the breakdown arc channel within the first half period of the discharge current cycle. The resulting arc discharge effects detonation of the fuel mixture through the cooperative effects of photolysis, supersonic hydrodynamic shockwave and high temperature thermal plasma. High voltage pulse generation distribution and switching circuits are provided. Several discharge electrode geometries and closely coupled pulse forming networks for the discharge device are disclosed.

Abstract: A combustion initiation system includes an initiating device for producing, containing and propelling a combustion initiating plasma having an energy density approaching that produced by combustion of the fuel itself, and is suitable for initiating combustion in relatively lean mixtures of various types of fuels. A high voltage power supply delivers electrical energy by a coaxial cable to the initiating device which communicates with a fuel mixture in a combustion area such as the combustion chamber of an ordinary internal combustion engine. The initiating device includes a capacitive portion for storing a large quantity of electrical energy therein derived from the power supply, and an electrode portion integral with the capacitive portion which comprises a pair of concentric, rod shaped electrodes for producing a high energy, umbrella shaped plasma discharge, using the inverse pinch technique.

Abstract: A plasma plug for use with an ignition system with improved plasma jet emmision is disclosed. The plasma plug comprises a threaded shell for engagement with an internal combustion engine, an annular ground electrode structurally integral with the shell, an insulator mounted therein, and a center electrode seated within the insulator. The center electrode and the insulator both have firing ends, the former of which is short of the latter and in spark gap relationship with the ground electrode. The insulator has a stepped cavity extending from the firing end of the electrode through the firing end of the insulator and having a cavity of relatively large cross-section adjacent the former and a cavity of smaller cross-section extending through the latter. The ratio of the volume of the large cavity to that of the smaller is from about 100:1 to about 1:1 and the ratio of the length of the large cavity to that of the smaller is from about 1:3 to about 1:1.

Abstract: A combustion initiation system includes an initiating device for producing, containing and propelling a combustion initiating plasma having an energy density approaching that produced by combustion of the fuel itself, and is suitable for initiating combustion in relatively lean mixtures of various types of fuels. A high voltage power supply delivers electrical energy by a coaxial cable to the initiating device which communicates with a fuel mixture in a combustion area such as the combustion chamber of an ordinary internal combustion engine. The initiating device includes a capacitive portion for storing a large quantity of electrical energy therein derived from the power supply, and an electrode portion integral with the capacitive portion which comprises a pair of concentric, rod shaped electrodes for producing a high energy, umbrella shaped plasma discharge, using the inverse pinch technique.

Abstract: A device for initiating combustion of fuels produces a high energy plasma jet by rapidly transferring energy from a capacitive section thereof to an electrode section integral therewith. A plurality of circular capacitor plates disposed in parallel, spaced relationship to each other within an electrically conductive, cylindrical casing filled with dielectric fluid form the capacitive section. The capacitor plates are alternately connected to the casing and to an elongate rod which extends longitudinally through the casing. One end of the rod extends outwardly from an end of the casing and includes a circularly shaped, pointed firing tip which is spaced from the end of the casing and defines one electrode of the device. The end of the casing surrounding the shaft defines the other electrode such that the initial discharge between the electrodes is in the form of a cylindrical sheet. The cylindrical sheet discharge is quickly transformed into a plasma jet by magnetic fields.

Abstract: Ignition plug for a rotary piston engine comprises a central electrode, an insulator disposed around the central electrode and having an end surface which defines a creeping discharge surface, and an outer electrode provided on an outer conductor. The outer electrode is radially inwardly projecting with respect to the radially inner surface of the conductor and has an axially and radially inward edge which is spaced apart from the insulator to provide an air gap for spark discharge and located flush with or axially outwardly of the end surface of the insulator.

Abstract: An ignitor for a liquid propellant gun having a center electrode supported nd surrounded by insulation so that only a planar or domed face is exposed. The assembly is firmly seated in the bolt nose of the gun and several outer electrode configurations with little or no precombustion area are disclosed.

Abstract: A spark plug for internal combustion engines having a center electrode, a ceramic insulator body and metal sleeve around the body. The sleeve defines an annular outside electrode around the center electrode with a concave depression in the insulator between the electrodes. The plug is operated at high current and voltage so that a high intensity spark will burn off any combustion residue on the relatively small insulator area between the electrodes. A process for removing combustion residues using this spark plug is also disclosed.

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: In a three electrode arc plasma flame ignition device, the first electrode surrounds the second electrode and the first and second electrodes define between them an annular gap across which the potential from a first source can be discharged, and the third electrode is surrounded by the second electrode and is so arranged that a higher potential applied to it discharges in series across a gap between the third electrode and the second electrode and radially across the annular gap between the second electrode and the first electrode.

Abstract: A spark plug having a cylindrical rod-shaped high voltage electrode and a metal sleeve press-fitted on the main body of the plug concentrically surrounding the electrode and having an inwardly projecting annular throat rib with a cylindrical inner surface concentrically completely surrounding the electrode and defining an annular firing space. The bottom end of the electrode extends down to at least the bottom of the cylindrical throat inner surface. Above the throat rib there is thus defined a resonating acoustical cavity, with the dimensions of the parts being such that the acoustic fundamental frequency is above ten thousand Hertz. The metal sleeve has an annular shoulder spaced from the bottom rim of the spark plug body to define an annular recess serving to induce high-multiple harmonics in the acoustic wave generated by the resonating cavity system.

Abstract: A surface-discharge igniter having concentric electrodes includes a gap at its operative tip which separates one of the electrodes from the exposed semiconductive surface of a semiconductive pellet that is interposed concentrically with the two electrodes. The said one electrode, which may be either the inner or outer electrode, is connected electrically to the pellet at the bottom of the gap away from the operative tip, whereas the other electrode makes contact with the pellet at, and in the region of, the exposed surface but is otherwise insulated electrically from it. Where the gap separates the inner electrode from the semiconductive surface then the outer electrode may be flared inwardly to establish its electrical connection with that surface. On the other hand, where the gap separates the outer electrode from the semiconductive surface the inner electrode may be flared outwardly, or provided with a cap that extends outwardly across the surface, to establish the connection with it.

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.

Abstract: Spark plugs having electrodes formed from combinations in defined proportions of tungsten, vanadium, depleted uranium, rhodium, iridium, palladium, nickel, chromium, copper, barium aluminate, iron, and thoria. Various advantageous electrode configurations are described, as well as methods of constructing the spark plugs.

Abstract: The spark plug has been designed so as to, be capable of being disassembled for cleaning, have a substantially full shield for the spark gap end of the center electrode portion, enable the center electrode to be readily replaced, if desired, enable partial cleaning of the spark plug gap area without removal of the spark plug from an associated engine, and have a substantially full gas seal defined between the base of the spark plug and the spark plug insulative sleeve.

Abstract: A combustion initiation system includes an initiating device for producing, containing and propelling a combustion initiating plasma having an energy density approaching that produced by combustion of the fuel itself, and is suitable for initiating combustion in relatively lean mixtures of various types of fuels. A high voltage power supply delivers electrical energy by a coaxial cable to the initiating device which communicates with a fuel mixture in a combustion area such as the combustion chamber of an ordinary internal combustion engine. The initiating device includes a capacitive portion for storing a large quantity of electrical energy therein derived from the power supply, and an electrode portion integral with the capacitive portion which comprises a pair of concentric, rod shaped electrodes for producing a high energy, umbrella shaped plasma discharge, using the inverse pinch technique.