Abstract: A fixing sleeve (2) for a spark plug (1) comprising coolant passages (3) which are arranged in the wall of the fixing sleeve (2) and which are oriented substantially in the longitudinal direction of the spark plug, wherein the fixing sleeve (2) comprises a metallic material whose thermal conductivity is over 60 W/m° C., preferably over 80 W/m° C.

Abstract: A glaze layer formed on the surface an alumina-based insulator of a resistor spark plug contains SiO2 (18 to 35% by weight), B2O3 (25 to 40% by weight), ZnO (10 to 25% by weight), BaO (7 to 20% by weight), Na2O (3 to 9% by weight), and K2O (3 to 9% by weight). Since the difference between the coefficients of linear expansion of the glaze and that of the alumina-based insulating material is relatively small, the glaze layer is less susceptible to cracks and the like. Also, since the glaze has a softening point lower than that of conventional lead-silicate-glass-based glaze, the glost-firing temperature can be as low as 800° to 950° C. Therefore, even in the case where glost firing is performed concurrently with a glass sealing step, a center electrode and a terminal metal piece are less susceptible to oxidation. Further, even though the content of the alkali metal component is high, a good insulating performance is obtained so that excellent flashover resistance is attained.

Abstract: The invention provides a spark plug having an insulator which is composed mainly of alumina, and which is more superior in voltage endurance characteristics at high temperatures as compared with the prior-art materials. An insulator 2 of a spark plug 100 is made of an insulating material which is composed mainly of alumina, and which contains Al component within a range of 95 to 99.7 wt % in weight converted to Al2O3, and in which an area ratio occupied by alumina base principal-phase particles with particle size not less than 20 &mgr;m is not less than 50% as a cross-sectional structure of the insulator is observed. By making the alumina base principal-phase particles appropriately coarse like this, the voltage endurance characteristics of the insulator can be remarkably improved.

Abstract: A spark plug for an internal combustion engine is disclosed in which lateral consumption of an electrode tip arising in the vicinity of a joined portion formed through welding is suppressed and which maintains excellent performance over a long period of time. The spark plug includes a center electrode which extends in the axial direction and is composed of a body and an electrode whose root end is joined to the end face of the body. The distance between a joined portion of the body and the electrode tip and the face of a free end of the electrode tip is at least 0.15 mm, particularly at least 0.2 mm. A diametral dimension of the electrode tip measured at a position located at the interface between the electrode tip and the joined portion and nearest to the free end of the electrode tip is at least 0.2 mm, particularly at least 0.25 mm, greater than a diametral dimension of the electrode tip measured at the free end. The depth of the joined portion is preferably not less than 0.

Abstract: An insulator for spark plug comprises an alumina-based sintered body comprising: Al2O3 (alumina) as a main component; and at least one component (hereinafter referred to as “E. component”) selected from the group consisting of Ca (calcium) component, Sr (strontium) component and Ba (barium) component, wherein the alumina-based sintered body comprises particles comprising a compound comprising the E. component and Al (aluminum) component, the compound having a molar ratio of the Al component to the E. component of 4.5 to 6.7 as calculated in terms of oxides thereof, and has a relative density of 90% or more.

Abstract: In a spark plug of the invention, as the top end edge of a terminal 13 is located within a middle trunk portion 2g of the insulator 2 with a longer reach of the screw portion 7, it acts as a support against fracture, more likely causing the problem of strength. Thus, the wall thickness of the middle trunk portion 2g at a position corresponding to the top end edge of the terminal 13 is sufficiently secured to be 0.42 or larger, based on the value of (D−d)/D, whereby it is possible to prevent the inconvenience such as fracture of the insulator, particularly, the middle trunk portion 2g from occurring owing to some strong force of bending, impact or torque applied on the insulator 2, when the spark plug is attached.

Abstract: In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 &mgr;m to 0.5 &mgr;m.

Abstract: In a spark plug, a main air gap (A) is formed between a parallel ground electrode (11) and the end face of a central electrode (2), a semi-surface gap (B) is formed between the end face (12C) of a semi-surface ground electrode (12) and the side face (2A) of the central electrode (2) and a semi-surface air gap (C) is formed between the end face (12C) and the side face (1E) of insulator. In addition, difference in a level E between the height of the lower end face (1D) of the insulator (1) and the height of the upper edge (12B) of the end face 12C of the semi-surface ground electrode 12 is E≦+0.7 mm, the distance B of the semi-surface gap (B) is longer than the distance A of the main air gap (A) and the distance C of the semi-surface air gap (C) and the insulator is shorter than the distance A of the main air gap (A).

Abstract: In a spark plug, a main gap is formed between the center electrode and the ground electrode, and an auxiliary gap is formed between the center electrode and a projecting inner edge formed at an open end portion of the metallic shell. The inner wall surface of the metallic shell extending from a terraced portion toward the tip end of the metallic shell is tapered such that the diameter of the inner wall surface decreases toward the tip end of the metallic shell by an amount of 0.6 mm or more. Through reduction of a gas volume defined by the insulator and the inner wall surface of the metallic shell, entry of high temperature combustion gas can be reduced to thereby decrease a thermal load imposed on the insulator, while entry of carbon can be minimized to thereby prevent contamination. Accordingly, heat resistance and contamination resistance can be significantly improved, and thus the range of operation of the spark plug can be widened.

Abstract: In a semi-creeping discharge type spark plug, a cylindrical metal shell and an insulator are provided, the latter of which has an axial bore and placed within the metal shell so that a front end of the insulator extends beyond the metal shell. A center electrode is placed within the axial bore of the insulator so that a front end surface edge of the center electrode retracts by 0.1˜0.6 mm behind from a front end surface of the insulator. A ground electrode, one end of which is connected to a front end of the metal shell, and the other end of which is bent to oppose an outer surface of the insulator so as to form an air-gap therebetween while permitting creeping spark discharges running along said front end surface of said insulator. A foward edge portion of a front end surface of the ground electrode extends by 0.0˜1.0 mm forward from the front end surface of the insulator.

Abstract: A spark plug assembly for an internal combustion engine has a housing, an electrode, an axis and a conducting member radially oriented relative to the axis has a collar disposed about the axis and connected to an end of the housing. The spark plug is connected to the engine and exposed to a combustion chamber of the engine. The collar extends a predetermined distance from the end of the housing and shields a gap between the conducting member and electrode from air swirl introduced into a combustion chamber.

Abstract: A spark plug with lower operating temperature has an electrode with a tip which evenly distributes heat imparted to the firing end portion of the spark plug. The electrical insulating material surrounding the electrode is spaced at a predetermined distance from the firing end portion of the spark plug to allow the heat to more quickly travel away from the firing end portion. An annular groove in the first end surface of the electrical insulating material minimizes electrical surface discharge between the electrode and the annular metal shell of the spark plug. Radii at locations of change in cross-section in the bore of the annular metal shell and the electrical insulating material serve to minimize voltage breakdown.

Abstract: In a spark plug, a resistor is placed between a terminal and a center electrode within a through hole of an insulator. The through hole of the insulator has a first portion which allows the center electrode to be inserted therethrough, and a second portion which is formed on a rear side of the first portion so as to be larger in diameter than the first portion and which accommodates the resistor therein, where the second portion is connected to the first portion via a connecting portion including a two- or more-stepped reduced-diameter portion. Then, an electrically conductive glass seal layer is placed at a position corresponding to the connecting portion between the resistor and the center electrode.

Abstract: A spark plug has an insulator having a through hole extending in an axial direction thereof and an insulator leg portion at an end thereof, a resistor disposed in the through hole, a central electrode disposed in the through hole to face a central electrode side end face of the resistor and protruding from an insulator end face of the insulator leg portion, and a housing holding the insulator. A length between the insulator end face and the central electrode side end face of the resistor is equal to or larger than 1.5 times as large as a length of the insulator leg portion in the axial direction. Accordingly, temperature at a contact portion between the resistor and the central electrode is prevented from being increased, resulting in long life of the spark plug.

Abstract: A spark plug derives an extended lifetime because a large plurality of sharp edges are provided on the center electrode, the ground electrode, or both to enhance spark propagation. In a first embodiment, the ground electrode has a conventional cantilever shape, but the center electrode extends into coplanar relation to a distal surface of the electrode so that sparks propagate from the cylindrical side walls of the center electrode. In variations of the first embodiment, the number of cantilevered ground electrodes is increased, with the ground electrodes being circumferentially and equidistantly spaced about the center electrode. In another embodiment, the ground electrode has an annular configuration and includes a cylindrical annular wall spaced radially outwardly of the cylindrical sidewall of the center electrode, in concentric relation to the center electrode.

Abstract: In a spark plug having a generally cylindrically shaped metallic body, a generally cylindrically shaped insulator held in the metallic body, a center electrode held in the insulator, and a ground electrode facing the center electrode, the insulator has a ramp portion on an outside surface thereof and the metallic body has a supporting portion for supporting the ramp portion of the insulator. Further, a conductive layer (a protection layer) is formed on the surface of the insulator to face the supporting portion of the metallic body. Accordingly, a corona discharge in a clearance between the supporting portion of the metallic body and the insulator is prevented, so that spike-like noise can be prevented.

Abstract: A spark plug having a center electrode with a cylindrical body with a tip at one end and a terminal near the other end with an insulator radially surrounding the center electrode. A ground shield surrounds the insulator and includes a ground electrode near one end, having a portion thereof with an annular opening disposed above and radially separated from the center electrode tip to form a radial spark gap, with a sealing portion disposed between the ground electrode and the other end of the ground shield for sealing the engine combustion chamber from the outside environment when the spark plug is installed. The ground shield can be formed from two parts which are deformed during manufacturing to be in mechanical engagement and securely holding the insulator in place. The spark plug can also have also have an integral or separate retainer for securing the spark plug to the engine.

Abstract: A spark plug for use in a combustion engine, which includes a spark plug body defining a central cavity; a electrode disposed within the cavity; a spring means disposed in one end portion of the central cavity; and a plate means operatively associated at one end with the spring means and adapted to communicate at its other end with the electrode whereby when the engine starts, the respective compression and explosion strokes move the plate means in one direction against the bias of the spring and in the opposite direction by the force of the spring, which in turn moves the other end of the plate in communication with the electrode in the same manner whereby combustion carbon collected on the electrode can be effectively removed.

Abstract: A spark plug for an internal combustion engine comprises a tubular metal ground shell, a first electrode passing through the interior of the shell, a ceramic insulator sealing the space between the shell and the first electrode and a second electrode extending from the shell to define a gap with the first electrode. The ratio of effective distance along the surface of the ceramic defining the potential surface discharge path to the distance between the first and second electrodes being selected to prevent surface discharge as the spark gap erodes.

Abstract: A spark electrode assembly and method of assembling same is disclosed. A ceramic housing having a cylindrical passage provides clearance for a conductive metal electrode. The electrode has a tubular body with rod shaped wires inserted at each end, the wires extending outwardly from the tubular body at each of its ends colinearly. During assembly, the wires are crimped into the tubular body in such a manner that the tubular body is deformed outwardly forming bosses. The bosses are of such a size as to cause an interference fit between the tubular body and the housing passage so that the electrode is captured within the housing. An impact force on the electrode forces the tubular body to expand radially outwardly, thereby further engaging the ceramic housing for holding the electrode in the housing. That part of the electrode body that is not in contact with the housing still has ample room to expand within the housing.

Abstract: A heater-equipped spark plug comprises an insulator having an insulator nose which holds thereon a center electrode in the vicinity of a free end of an axial bore, a lead wire arranged along a surface of the insulator, a heater formed on the insulator nose by baking a metal paste and connected to the lead wire; and a high softening-point glass layer covering and holding the heater in place with an alumina layer interposed between the high softening-point glass and the heater. Preferably, the alumina layer can have a thickness of 20-200 .mu.m and the high softening-point glass layer can have a thickness of 30-500 .mu.m.

Abstract: A spark plug includes a ground electrode, a firing electrode, an insulator core, and an outer shell surrounding the insulator core. The outer shell has a threaded section for mounting the spark plug in a combustion engine and a splined section for installation of the spark plug. The splined section includes at least one spline having an outer surface and a corresponding castellation recessed from the outer surface.

Abstract: A spark plug for use in conventional fuel ignition systems includes a housing and a ground electrode attached to the housing. A center electrode is located within the housing and is spaced apart from the ground electrode to form an electrode gap. An insulation member electrically separates the center and ground electrodes. A sub-combustion chamber is further located on the spark plug and encloses the electrode gap. A plurality of holes are located within the walls of the sub-combustion chamber where both a fuel-air mixture and combustion gasses pass through.

Abstract: By heating a glass sealing material, a center electrode is sealed and fixed within an axial bore of an insulator. Formation of a groove in a head portion of the center electrode makes it possible to protect the head portion of the center electrode from deformation under a pressure which is applied upon filling the glass sealing material in a powder form in the axial bore. The glass sealing material is therefore assured to flow to a peripheral side wall of a flange portion of the center electrode, thereby enhancing mechanical engagement between the center electrode and the insulator, that is, uniting strength for them. A spark plug is hence obtained with improved impact resistance and accordingly, with sufficient durability.

Abstract: A threaded portion is formed on a metal shell of a spark plug. Within a mounting base of the metal shell, a pressure sensor is arranged in such a direction that it generates an electrical signal in response to a variation in a tightening load of the spark plug. A slit is formed as a pressure-introducing channel along an axis of the spark plug in the threaded portion of the metal shell so that the slit is communicated with an interior of the mounting base.

Abstract: A plurality of ultrasound whistles formed into a ceramic core of a conventional spark plug used in a cylinder of a gasoline combustion engine for greatly improved air fuel mixture prior to ignition. The spark plug with ultrasound whistles provides for increased engine performance and acceleration, improved fuel mileage and an improvement cleaner burning air fuel mixture thereby providing for reduced fuel emissions into the environment. The ultrasound whistles are constructed in the form of whistle holes. The whistle holes are disposed around a circumference of the ceramic core in a spaced relationship and next to the spark plug's electrode. The holes have a depth in a range of 0.032 to 0.050 inches. Also, the whistle holes have a diameter in a range of 0.031 to 0.033 inches. Around the top of the small closed end whistle holes are upwardly extending lips. The upwardly extending lips have a height above the surface of the ceramic core of 0.015 to 0.040 inches.

Abstract: A spark ignition electrode assembly includes an electrode wire and an electrically insulative support member receiving and positioning the electrode wire proximate to the gas burner. The electrically insulative support member includes a threaded outer wall portion for receipt within a corresponding internally threaded aperture in the cooktop wall. The threaded outer wall portion is threadingly inserted in the corresponding cooktop aperture for positioning the spark ignition electrode assembly with the gas burner.

Abstract: A spark plug derives an extended lifetime because a large plurality of sharp edges are provided on the center electrode, the ground electrode, or both to enhance spark propagation. In a first embodiment, the ground electrode has a conventional cantilever shape, but the center electrode extends into coplanar relation to a distal surface of the electrode so that sparks propagate from the cylindrical side walls of the center electrode. In variations of the first embodiment, the number of cantilevered ground electrodes is increased, with the ground electrodes being circumferentially and equidistantly spaced about the center electrode. In another embodiment, the ground electrode has an annular configuration and includes a cylindrical annular wall spaced radially outwardly of the cylindrical sidewall of the center electrode, in concentric relation to the center electrode.

Abstract: In a spark plug, a cylindrical metal shell is provided whose inner wall has a ledge portion on which an insulator rests through its seat portion. The insulator has an axial bore in which a center electrode is placed whose front end has a heat-resistant metal tip. A ground electrode is provided to form a spark gap with the noble metal tip of the center electrode. The insulator forms an insulator nose which measures less than 15 mm in length. The heat-resistant metal tip measures less than 0.8 mm in diameter. A space between an outer surface of the center electrode and an inner wall of a front open end of the axial bore is defined to be more than 0.1 mm in width.

Abstract: In a spark plug for use for an internal combustion engine, an elongated insulator is provided in which a center electrode is supported. A cylindrical metal shell is provided in which the insulator is supported, and a ground electrode extends from the metal shell to form a spark gap with a front end of the center electrode. The front end of the center electrode has a tapered-off step section whose front end surface has a spark erosion resistant portion, and having a boundary between a columnar portion of the center electrode and the tapered-off step section. The boundary of the tapered-off step section is located within a front end surface of the insulator, and a front end surface of the tapered-off step section is positioned outside of the front end surface of the insulator.

Abstract: In a spark plug including a cylindrical metal shell whose inner wall has a ledge portion, an insulator having a seat portion which engages with a rear slope surface of the ledge portion to be supported within the metal shell, a center electrode supported with an axial bore of the insulator, and a ground electrode extended from the metal shell to form a spark gap with the center electrode. A dimensional relationship among (A), (B) and (g) is defined as follows: {(B-A)/2}.gtoreq.0.8.times.(g) or {(B-A)/2}.gtoreq.0.9.times.(g). Where B (mm) is an inner diameter of a metal shell portion which surrounds an insulator nose, A (mm) is a base diameter of the insulator nose, and g (mm) is a width dimension of the spark gap.

Abstract: A cambered shape of an external negative electrode (11) of an internal combustion engine's spark plug so that a spark bridging the plug's spark gap (17) impinges first at the base region (14) and travels outward and around to initiate burn of almost 100% of available fuel. The cambered shape culminates with an end section (16) that is 1/4 of a sphere and has symmetry to the radial edge of a center electrode (13).

Abstract: A spark plug for an internal combustion engine comprising: a cylindrical metal tube; a rod-shaped central electrode within the cylindrical metal tube; a tubular insulator within which the rod-shaped central electrode is located, wherein the tubular insulator is arranged substantially centrally in and substantially coaxially with the cylindrical metal tube; and at least two ground electrodes affixed to the cylindrical metal tube, wherein the at least two ground electrodes are each bent toward the metal electrode, wherein each ground electrode together with the central electrode forms a different member of a set of spark paths comprising: (i) an air sliding spark path, (ii) and air-air sliding spark path and (iii) an air spark path.

Abstract: A spark plug is provided for internal combustion engines in which a tapered chamber or thrust nozzle is provided that terminates at the spark gap. The thrust nozzle is provided with a plurality of openings whereby fuel/air mixture is drawn from the main combustion chamber into the thrust nozzle in contolled flow.

Abstract: In a spark plug insulator made of a sintered ceramic body, including aluminum nitride (AlN) or aluminum oxynitride (AlON) ceramic powder having an average grain size of 1.5 .mu.m in which the oxygen content of the aluminum nitride or the aluminum oxynitride powder is less than 2 percent by weight. Magnesium (Mg) is also present in an amount in the range from 0.01 wt. % to 5.0 wt. % where the amount of the magnesium (Mg) is calculated by converting the magnesium (Mg) to its oxidized compound (MgO). Also included is a sintering additive present in an amount up to 10 wt. % selected from the group consisting of rare earth metal compounds in which the weight percentage of the sintering additive is calculated by converting the sintering additive to its oxidized compound. The rare earth metal compound is selected from the group of yttrium oxide (Y.sub.2 O.sub.3) calcium oxide (CaO), barium oxide (BaO), strontium oxide (SrO), scandium oxide (Sc.sub.2 O.sub.2), europium oxide (Eu.sub.2 O.sub.

Abstract: A spark plug (11) having a center conductive path (21) with a cylindrical body having a tip (33, 51, 77) at one end and a terminal (23) near the other end has an insulator (41, 45) radially surrounding the center electrode and a substantially cylindrical body with at least first and second diameter sections separated by a shoulder (29). A ground shield (37) surrounds the insulator first diameter section and including near one end a frustoconical section (31) juxtaposed with the insulator shoulder. There is a ground electrode (55, 57, 73) near the other end having a portion thereof (53, 75) aligned with the center electrode tip to form a spark gap. An annular retainer (59) surrounds the insulator second diameter section and including a threaded portion (61) threadedly engaging the threaded portion (17) of a generally cylindrical opening in the head of an internal combustion engine.

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 plug for an internal combustion engine having one or more electrode diagonally projecting from a central electrode into a V-shaped grounding window which is cut into the skirt of the spark plug body. The novel electrode suspended in the grounding window provides broader spark dispersion, through a wider arching area, and greatly improved spark plug life.

Abstract: A spark plug has a base with a bottom end portion adapted to be received and retained by a cylinder head of an internal combustion engine. An insulator retains a central electrode within the base with a combustion chamber end of the electrode extending into a combustion chamber of the engine when the plug is installed in the cylinder head. The central electrode combustion chamber end includes a combustion chamber end face with a hole having the physical characteristics of an acoustically tuned pipe with an open and a closed end formed in its surface. A ground electrode is attached to the base and defines a spark gap between its inner surface and the central electrode face. The ground electrode has a hole passing through it which has the physical characteristics of an acoustically tuned pipe with two open ends.

Abstract: A precombustion chamber ignition device for preferably lean fuel-air mixtures and having a precombustion chamber. This precombustion chamber contains a electrode carrier extending into the precombustion chamber and on it at least one ignition electrode is attached, which has at least one ignition portion, which cooperates with a internal wall surface of the precombustion chamber in defining at least one spark gap extending substantially athwart the longitudinal axis of the precombustion chamber. In this respect the internal wall surface acts as a ground electrode. The ignition portion of the at least one ignition electrode is offset in relation to the longitudinal axis of the precombustion chamber and is arranged essentially parallel to the wall surface, which is substantially cylindrical in the spark gap portion, of the precombustion chamber close to the wall surface.

Abstract: In a spark plug insulator for use in an internal combustion engine, a sintered body has boron nitride and a metal oxide, the boron nitride of the sintered body being 80% or greater by weight, and the sintered body having a thermal expansion coefficient of less than 5.0.times.10-.sup.6 /.degree.C. The metal oxide is selected alone or in combination from the group consisting of magnesium oxide, calcium oxide, silicon oxide, boron oxide, yttrium oxide and aluminum oxide.

Abstract: A spark plug includes a cylindrical metallic shell having a shoulder portion, and a tubular insulator having a stepped portion which rests on the shoulder portion within the metallic shell. The insulator has a rear half made of aluminum oxide and a front half made of aluminum nitride, the rear half having a protrusion, while the front half having a housing, and tightly joining the protrusion within the housing. An overlapping portion of the protrusion and the housing is at least partly located in a plane which is perpendicular to a longitudinal axis of the center electrode, the plane passing through the shoulder portion of the metallic shell.

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: In an electrode for a spark plug, an elongated blank metal is made of a nickel-based alloy and including a front surface. A firing tip is provided from a slug made of a noble metal, the slug being concentrically placed on the front surface of the elongated blank metal and laser beam welded to thermally melt the entire slug and thereby produce a thermal weld, so that the front surface of the elongated blank metal is partly fused together with the slug to form a melted portion with the front surface and the slug so as to contain the front surface within the melted portion in the range of 0.5 wt % to 80.0 wt %.

Abstract: In a center electrode for a spark plug, the center electrode is made of a heat-conductor core cladded with a nickel-alloyed metal. A recess is provided on the front end surface of the nickel-alloyed matrix and the columnar tip is made of a precious metal and fit in the recess in such a manner that a front end of the tip protracts from the recess. The outer surface of the tip is welded to an inner surface of the recess. The dimensional relationship of the components of the spark plug A, B, C, D, E, F and G is as follows: 0.3 mm.ltoreq.A.ltoreq.0.8 mm, 1.2A.ltoreq.B.ltoreq.3A, 0.1 mm.ltoreq.(C-A)/2.ltoreq.0.5 mm, D.ltoreq.(C-A)/2, E.ltoreq.B/4, 0 mm.ltoreq.F.ltoreq.0.5 mm and A/5.ltoreq.G.ltoreq.

Abstract: An improved igniter and cable connector assembly for turbine engines. An igniter mounting adapter is secured to the engine. The igniter slides into a hole through the adapter and is retained by an enlarged head on the igniter. An annular seal is positioned around a high voltage terminal on the igniter head and a terminal on the cable connector is positioned against the igniter terminal. The cable connector is secured to the adapter, for example, by either a clamp assembly or a coupling nut or a quick release connector. As the cable connector is secured to the adapter, the seal is compressed between the igniter and connector insulators and, optionally, the connector terminal is rotated and pressed against the igniter terminal to establish a reliable electrical contact. The connector and igniter terminals preferably have mating conical or spherical surfaces, one of which may be an annular segment to provide an increased electrical contact area.

Abstract: A spark plug insulator is desirably made up of a sintered body of AlN-based ceramic powder comprising about 60-98% AlN and a sintering additive. There is provided on the surface of the sintered body a layer of pyrolytic boron nitride having a thickness in the range 10-100 .mu.m.

Abstract: A spark plug is provided for an internal combustion engine and includes a center electrode having a combustion chamber end and a ceramic insulator having an end portion over which an ablative coating is formed for removing contaminants deposited thereon. The ablative coating is capable of ablating completely during sustained operation of the spark plug.

Abstract: A spark plug for an internal combustion engine includes a metallic shell within which a tubular insulator is placed, a center electrode is provided within the insulator to form a spark gap between a front end of the center electrode and an outer electrode extending from the metallic shell. First and second stepped portions are provided near a front portion of the center electrode to form a clearance between an outer wall of the center electrode and an inner wall of the insulator. The stepped portions have a progressively decreasing diameter toward the front end of the center electrode. A tapered portion is provided at an inner wall of the insulator by bevelling a front open end of the insulator. This maintains high insulation of the insulator with significantly low carbon deposit, thus avoiding ignition failure of the spark plug.

Abstract: A plasma ignitor system capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. The plasma ignitor features a high energy current pulse source and a geometrically configured coaxial, dual-rail or three-rail ignitor system for deeper and more accurate injection of plasma into a combustion chamber of either large or small dimension.