Abstract: A plasma jet spark plug capable of preventing a channeling progress and having excellent heat conduction. The plasma jet spark plug comprised of: a ceramic insulator having a small diameter portion which assumes a linear shape in an axial direction, and a center electrode has an outer diameter increasing in the order of a frontmost portion, a step portion, a front end portion and a body portion.

Abstract: A ground electrode is provided having a ground electrode body, the ground electrode body having an anchored end and a non-anchored end opposite the anchored end. The ground electrode includes a plateau extending from a surface of the ground electrode body adjacent the non-anchored end. In illustrative embodiments, the plateau is formed by removing a portion of the ground electrode body near the non-anchored end. The plateau is configured to be exposed around its periphery. A noble metal tip is fixably attached to the plateau.

Abstract: A spark plug including: a central electrode including an upper end and a lower end; an insulating part including an upper portion and a lower portion and surrounds the central electrode so that the lower end of the central electrode extends beyond the lower portion of the insulating part; and a cap including an upper portion and a lower portion that has an end section and that surrounds the insulating part so that the lower portion of the insulating part extends beyond the lower portion of the cap. The insulating part includes an annular groove, on the external periphery thereof, on the lower end of the cap, and the lower end section of the cap is placed in the groove.

Abstract: In a spark plug that has a small sized center electrode, enhancement of corruption-resisting property and heat-resisting property is promoted. The spark plug 1 includes a center electrode 5, an insulator 2 and a metal shell 3, and the insulator 2 includes a foot section 13, a tapered section 14 and a middle body section 12. The maximum outer diameter of a portion, which is arranged within the foot section 13, of the center electrode 5 becomes 3.0 mm or less. A step section 21 and a leading end side inner periphery section 51 are formed in the inner periphery of the metal shell 3 and the tapered section 14 is engaged to a step section 21. When A (mm3) is a volume of a portion of 2 mm of the insulator 2 from leading end of the insulator 2 toward the rear end side along the axis CL1 and B (mm3) is a volume of a portion of the insulator 2 from the rear end of the portion of the tapered section 14 which is engaged to the step section 21 to the leading end side and the portion is 1.

Abstract: A spark plug includes a terminal for receiving an electrical charge, a firing electrode on a firing end of the spark plug, and a conductor electrically coupling the terminal and firing electrode. The spark plug further includes a casing, an electrical insulator, and a ground electrode. The casing is at least partially formed from an electrically conductive material and is configured to be electrically coupled to a ground. The electrical insulator separates the conductor from the casing. The ground electrode is positioned proximate to the firing electrode, but separated from the firing electrode by a spark gap. The ground electrode includes an extension projecting from the casing such that the firing electrode is closer to the ground electrode than the firing electrode is to the casing. There is substantially no air gap between the interior of the casing and the electrical insulator from the firing end of the spark plug.

Abstract: A spark plug includes a tubular metal shell, an insulator, a cylindrical center electrode, and a ground electrode. The ground electrode has an inclined portion, a straight portion, and a bend between the inclined and straight portions. The inclined portion extends obliquely with respect to the axial direction of the center electrode from a base end of the ground electrode, which is joined to an end of the metal shell, to the bend that is positioned closer to the center electrode in the radial direction of the center electrode than the base end. The straight portion extends substantially parallel to the axial direction of the center electrode from the bend to a tip end of the ground electrode. The straight portion has an inner side surface facing the side surface of an end portion of the center electrode through a spark gap in the radial direction of the center electrode.

Abstract: A spark plug includes an electrode tip assembly located at an axially-facing free end surface of an electrode body. The electrode tip assembly includes an electrode tip body and a firing tip and has a longitudinal axis that is generally perpendicular to a longitudinal axis of the electrode body. The electrode tip body may be a Ni-alloy piece and is attached to the electrode body, and the firing tip may be an Ir-alloy piece with a sparking surface that faces a spark gap. The electrode body may include a groove formed in the axially-facing free end surface that is useful to help position the electrode tip assembly for attachment. The spark gap can be formed between opposing electrode tip assemblies, and the size of the spark gap can be adjusted during assembly without the need for bending the electrode body.

Abstract: A spark plug (1) includes an insulator (2) and a metal shell (3), including a middle section (41) positioned between a collar section (16) and a tool engaging section (19). The middle section (41) has a bulged section (42), a first slender section (43) and a second slender section (44) that is the most slender at a portion positioned further to the leading end side than the bulged section (42). In a cross-section including the axis CL1, when the distance between both slender sections (43) and (44) along the axis CL1 is F (mm) and the bulged amount to the inside in diametrical direction of a most bulged section (42M) with respect to an imaginary line that connects a portion that is positioned furthest to the inside in diametrical direction of both slender sections 43 and 44 is G (mm), the relationship 0.00<G/F?0.18 is satisfied.

Abstract: A spark plug (1) includes a center electrode (5), an insulator (2), a metallic shell (3), a ground electrode (27), and a noble metal tip (32) provided on at least one object member of the center electrode and the ground electrode. One end surface of the noble metal tip is joined to the object member via a fusion zone (35). The fusion zone includes a first fusion zone (351) formed through radiation of a laser beam or the like to the boundary between the object member and the one end surface of the noble metal tip along a perimetrical direction of the noble metal tip, and a second fusion zone (352) formed through radiation of the laser beam or the like from the side from which the laser beam or the like has been radiated in forming the first fusion zone, and intersecting with the first fusion zone.

Abstract: A spark plug includes a tubular metal shell extending in an axial direction, wherein the metal shell includes: an externally threaded portion formed on a tip end side of an outer periphery of the metal shell; a seat portion formed on a rear end side of the externally threaded portion in the axial direction and protruding radially outward; and a nickel layer provided on an outer surface of the metal shell, wherein the nickel layer contains phosphorus, and a phosphorus concentration in a portion in which a nickel concentration is 50 at % in a thickness direction of the nickel layer itself is 6 at % or more and 20 at % or less.

Abstract: A spark plug has a metal shell and a ground electrode joined at a base end portion thereof to the metal shell and includes a surface layer and a core higher in thermal conductivity than the surface layer. The surface layer has a thickness of 0.2 to 0.4 mm at a specific position that is located 1 mm from the base end portion. The spark plug satisfies the following condition: W1?W2×1.55?(W3+0.25) where W1 (mm) is a width of the metal shell at a weld region of the metal shell joined with the base end portion in a specific direction that extends perpendicular to the axis direction through a center line of the ground electrode; W2 (mm) is a thickness of the ground electrode at the specific position in the specific direction; and W3 (mm) is a thickness of the surface layer at the specific position in the specific direction.

Abstract: The spark plug for an internal combustion engine has a cylindrical housing, a center electrode held inside the housing, a ground electrode connected to the housing and forming a spark discharge gap between itself and the center electrode, and, an end projection projected from the end portion of the housing toward the head end side of the spark plug. The center electrode and ground electrode are arranged so that most of the spark discharge gap is disposed over the open areas and the electrode area in which the end projection is arranged.

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 a ceramic insulator having an axial hole formed in an axis direction of the spark plug, a center electrode inserted in a front side of the axial hole, a metal shell disposed around the ceramic insulator and a ground electrode joined to a front end portion of the metal shell, wherein the ground electrode has a cross-sectional area of 2.0 mm2 or smaller in any arbitrary cross section thereof taken in a direction perpendicular to a center line of the ground electrode; the ground electrode is made of a metal material containing 93 mass % or more of nickel; and the ground electrode has a Vickers hardness of 130 to 260 Hv.

Abstract: In a spark plug, a fusion zone where a ground electrode and a noble metal tip are fused together is formed in at least a portion of an interfacial region between the ground electrode and the noble metal tip. When the fusion zone is projected in the axial direction, the projected fusion zone overlaps 70% or more of the area of the noble metal tip. As viewed on a section which passes through the center of gravity of the noble metal tip and is perpendicular to the longitudinal direction of the ground electrode, the relational expression 1.3?B/A is satisfied, where A is the greatest thickness of the fusion zone along the axial direction, and B is the length from a portion having the greatest thickness of the fusion zone to the inner end of the fusion zone.

Abstract: A spark plug electrode, which is produced from an electrode material containing nickel as base material, 0.5 to 3 atom % of silicon, and at least 6 atom % of aluminum.

Abstract: Provided is a manufacturing method for manufacturing a spark plug which produces a spark plug which mitigates misfire and improves gas mileage, peak engine performance, horsepower, and increases the RPM range of the host vehicle. The improved performance of the spark plug is, at least in part, attributable to the spacing between an electrode body and an electrode cage. In particular, the electrode cage extends over the electrode body such that the arcuate members of the electrode cage are equidistantly spaced from the bulbous or spherical electrode body. The manufacturing method described herein results in a spark plug having the above-described configuration, while being formed and assembled at an economical cost.

Abstract: A method of producing an electrode support for a spark plug is provided. The method includes attaching a chip to the electrode support. The chip includes a section of sacrificial material located between two sections of electrode material. The method includes substantially removing the section of sacrificial material from the chip to create a spark gap between the two sections of electrode material.

Abstract: A spark plug including a center electrode; an insulator; and a metal shell, the metal shell including: a tool engaging section; a body section; and a groove section formed between the tool engaging section and the body section, and having bulges which bulge in an outer peripheral direction and in an inner peripheral direction. When a portion of the groove section having a largest outer diameter is a first section, a thinnest portion from the first section to the body section is a second section, and a portion having a thickness that is the same as that of the first section is a third section, a relation between a thickness A of the second section and a radius of curvature R of an outer surface of the metal shell that continues from the second section to the third section satisfies R×A?0.20 mm2.

Abstract: A spark plug having one or more electrodes at least partially fabricated from an aluminum-containing Ni-based alloy. The alloy is a volume-stable alloy that includes a Ni3Al precipitate in a ??-phase distributed in a Ni matrix ?-phase. The precipitate is formed in the alloy prior to the alloy being used to fabricate electrodes and thus prevents additional Ni3Al precipitate from being formed in the alloy once in service in a high-temperature environment. This, in turn, prevents a volume decrease of the alloy that may lead to an increased spark gap and spark plug malfunction. The volume-stable alloy may be made by solution treatment, quenching, and heat aging of a Ni—Cr—Al—Fe alloy.

Abstract: In a spark plug in which one end of a ground electrode 9 is welded to a front end surface (7a) of a tubular metallic shell (7), the following relations (1) and (2) are satisfied: K?1.1A??(1) K?(D?d)/2??(2) where A represents the wall thickness of the metallic shell in the radial direction measured on the front end surface at a position where the wall thickness becomes the minimum; d represents the maximum inner diameter of the front end surface; D represents the minimum outer diameter of the front end surface; and K represents the wall thickness in a region of the front end surface where the ground electrode is welded to the front end surface.

Abstract: A spark plug includes at least one of a center electrode or a ground electrode that is produced by the steps of: mixing a matrix metal with carbon so that the carbon content of the resultant mixture is adjusted to 80 vol. % or less; subjecting the mixture to powder compacting or sintering, to thereby form a core; placing the core in a cup formed of nickel or a metal containing nickel as a main component; and subjecting the cup to cold working. The thus-produced electrode exhibits favorable thermal conductivity and good heat dissipation, by virtue of the small difference in thermal expansion coefficient between the core and an outer shell. The spark plug including the above electrode exhibits excellent durability.

Abstract: A spark plug is provided having at least one of a center electrode or a ground electrode. The electrode comprises: a core formed of a composite material containing a matrix metal, the matrix metal being copper or a metal containing copper as a main component, and carbon dispersed in the matrix metal in an amount of 10 to 80 vol. %, the carbon having a thermal conductivity higher than that of the matrix metal. The electrode also contains an outer shell which surrounds the core and which is formed of nickel or a metal containing nickel as a main component. The thus-produced electrode exhibits favorable thermal conductivity and good heat dissipation, by virtue of the small difference in thermal expansion coefficient-between the core and an outer shell. The spark plug including the above electrode exhibits excellent durability.

Abstract: A method of producing an electrode support for a spark plug is provided. The method includes attaching a chip to the electrode support. The chip includes a section of sacrificial material located between two sections of electrode material. The method includes substantially removing the section of sacrificial material from the chip to create a spark gap between the two sections of electrode material.

Abstract: A spark plug (1) including a noble metal tip joined to a ground electrode and forming a spark discharge gap in cooperation with a center electrode. A surface of the noble metal tip which forms the gap has an area of 0.9 mm2 or greater. The noble metal tip (32) is joined to the ground electrode (27) via a fusion zone (35) formed by irradiating at least one surface among a distal end surface and side surfaces of the ground electrode with a laser beam or an electron beam. Further, as viewed on a projection plane orthogonal to a center axis of the noble metal tip and on which the noble metal tip and the fusion zone are projected along the center axis, an overlapping region between the noble metal tip (32) and the fusion zone accounts for 70% or more of a projected region of the noble metal tip.

Abstract: An adhesion of a nickel plating layer to a metal shell is improved, and an effect of improving a corrosion resistance by providing the nickel plating layer is sufficiently exerted. A spark plug 1 includes a cylindrical metal shell 3 that extends in an axial CL1 direction, and a nickel plating layer 31 that is made of metal containing nickel as a main component and covers an outer surface of the metal shell. In a monochrome image of 256 gradations where black is 0 and white is 255, which is obtained by observing a cross-section perpendicular to an outer surface of the nickel plating layer by a transmission electron microscope with an acceleration voltage of 200 kV, an average value in 256 gradations of the monochrome image is 170 or larger and 230 or smaller.

Abstract: A spark plug which exhibits high dielectric strength at high temperature and which is unlikely to be deteriorated in dielectric strength is provided. The spark plug includes a center electrode, an insulator, and a metallic shell. The insulator includes an alumina-based sintered body which contains a silicon component, a Group II element component, and a rare earth element component. The alumina-based sintered body is composed of a glass phase and an alumina crystal phase as observed through X-ray diffraction analysis. When the grain boundary phase of the alumina-based sintered body is observed under a transmission electron microscope, and the weight ratio between an alkali metal component and the rare earth element component as reduced to oxides thereof [alkali metal/rare earth element] is calculated at 30 circular spots, each having a diameter of 0.3 nm, selected arbitrarily in a field of observation, the average of the weight ratios of the 30 spots falls within a range of 0.01 to 1.0.

Abstract: A spark plug 20 includes a center electrode 22 and a ground electrode 24 providing a spark gap 26 therebetween. At least one of the electrodes 22, 24, but preferably both electrodes 22, 24 include a clad surrounding a core. The clad includes at least one metal, such as nickel, iron, or cobalt. The core includes nanocarbon material embedded in a copper matrix 40 to increase the thermal conductivity and reduce the coefficient of thermal expansion of the core. The nanocarbon material includes a plurality of fibers 42, also referred to as particles, whisks, or tubes, each having a diameter of 1.0 to 150.0 nanometers and a length of 1 ?m to 100 ?m. The core includes the nanocarbon material in an amount of 0.1 to 10.0 wt. %.

Abstract: In process of threadably fitting a metal shell having a surface formed with an Ni plated layer into a mounting hole, in a state where a gasket made of stainless steel is uncompressed while being interposed between a protrusion part and an opening periphery, a surface of the gasket is out of contact with another surface thereof. When the gasket is viewed on a cross section in a direction of an axial line O, the gasket contacts with the protrusion part at one point of a point X, the gasket contacts with the opening periphery at one point of a point Y, and the point Y is located outside of the point X in a radial direction. Further, the point Y is located inside of a maximum outer diameter Dz of a seating surface of the protrusion part in the radial direction.

Abstract: A spark plug includes an inner conductor, an ignition tip connected to the inner conductor, an insulator surrounding the inner conductor and having a front end and a rear end, a spark plug body having a front end and a rear end, and at least one ground electrode connected to the front end of the spark plug body. The spark plug has a longitudinal direction extending parallel to the inner conductor. The spark plug body comprises a passage extending in the longitudinal direction and in which the insulator is disposed. A sleeve composed of metal is disposed between the insulator and the spark plug body. The sleeve is tightly connected to the insulator and the spark plug body and is referred to below as the “first sleeve”. At least one second sleeve is disposed at a distance from the first sleeve) and, in fact, between the first sleeve and the rear end of the insulator. The second sleeve is connected to the insulator and touches the spark plug body in the passage thereof.

Abstract: A ground electrode and a metal shell are joined by welding or the like while an entire end face of a base of the ground electrode is brought into contact with a front end constituent face of the metal shell. The ground electrode has an extending portion extending forward in an axial (O) direction of the ground electrode. A front end portion faces a noble metal tip joined to a front end portion of the center electrode through a bending portion and forms a spark discharge gap (G) therebetween. A gap (a clearance) having a sufficient space to accommodate a virtual sphere (Q) with a radius of 1.2 mm is provided so that the virtual sphere (Q) being in contact with an inner face of the bending portion of the ground electrode is neither in contact with a center electrode nor an insulator.

Abstract: The present invention provides a spark plug which is capable of suppressing a occurrence of crack and separation by determining a structural configuration of a melting portion formed in a junction portion between a discharge portion and a pedestal portion which form an ignition portion that protrudes from a ground electrode. In a profile line shape of a cross section including a center axis P of an ignition portion 80, an exposure surface 88 of a melting portion 83 connects a side surface 82 of a discharge portion 81 and a side surface 85 of a pedestal portion 84. Further, an exterior angle ? formed between an imaginary line Q, which passes through a boundary position X1 between the melting portion 83 and the pedestal portion 84 and a boundary position X2 between the melting portion 83 and the discharge portion 81, and the center axis P at a node C, satisfies 135°???175°.

Abstract: Method for manufacturing a spark plug comprising an inner conductor, an insulator enclosing the inner conductor, a spark plug body enclosing the insulator, and two electrodes, the first electrode being a center electrode connected to the inner conductor in an electrically conductive manner, and the second electrode being a ground electrode connected to the spark plug body in an electrically conductive manner, with a separately prefabricated precious metal component positioned on one of the electrodes and connected to the electrode by way of resistance welding, and subsequently affixed by way of laser or electron beam welding, so that the precious metal component extends like a heel beyond the electrode surface next to the precious metal component. The precious metal component, a ball is shaped by stamping after resistance welding and before laser or electron beam welding, wherein at least one region of the ball protruding from the electrode surface is reshaped.

Abstract: High-frequency plasma spark plug includes an insulator which has an axial hole extending in the axis direction, a center electrode inserted into a distal end side of the axial hole, a terminal electrode inserted into a rear end side of the axial hole, and being electrically connected to the center electrode, and a cylindrical main fitting mounted on an outer periphery of the insulator. With respect to a coaxial cable, the inner conductor is connected to the terminal electrode and the outer conductor is connected to the main fitting. High frequency power generated by a predetermined high-frequency power source is supplied via the coaxial cable thus generating high frequency plasma. The main fitting includes a large diameter portion which bulges radially outward and a connection portion which is brought into contact with the outer conductor.

Abstract: In joining a composite tip to an electrode, a method is used for properly adjusting the height of radiation of a laser beam to the height of the boundary between two tips used to form the composite tip. Further, a process for joining a first tip and a second tip together by use of a laser beam includes the steps of; (a) disposing the second tip on a support; (b) obtaining, after pressing downward at least the second tip by the use of a pressing jig, a correction value for correcting the height of radiation of a laser beam; (c) correcting the height of radiation of the laser beam on the basis of the correction value; and (d) joining the first and second tips together by use of the laser beam.

Abstract: A ruthenium-based electrode material for use with a spark plug. The electrode material comprises ruthenium (Ru) and a precious metal. The ruthenium (Ru) is the single largest constituent of the electrode material on a wt % basis. The electrode material may have a density that is less than or equal to about 15.5 g/cm3 and may include at least one other precious metal. The electrode material may be used in a spark plug that includes a metallic shell having an axial bore, an insulator having an axial bore and at least partially disposed within the axial bore of the metallic shell, a center electrode at least partially disposed within the axial bore of the insulator, and a ground electrode attached to a free end of the metallic shell. The center electrode, the ground electrode or both may be formed at least in part from the electrode alloy.

Abstract: A spark plug, a center electrode therefore and method of construction is provided. The spark plug has a generally annular ceramic insulator extending between a terminal end and a nose end. A conductive shell surrounds at least a portion of the ceramic insulator and a ground electrode having a ground electrode sparking surface is operatively attached to the shell. An elongate center electrode has a body extending between opposite ends, wherein the body is compacted and sintered of a conductive or semi-conductive ceramic material. One of the electrode ends provides a center electrode sparking surface to provide a spark gap between the center electrode sparking surface and the ground electrode sparking surface.

Abstract: A spark plug having a metallic shell covered with a nickel plating layer and having a groove portion formed between a tool engagement portion and a gas seal portion and having an orthogonal-to-axis sectional area of 36 mm2 or less.

Abstract: This invention relates to a corona discharge ignitor used to ignite air/fuel mixtures in automotive applications and the like. To suppress an arc from forming when a voltage is applied to the ignitor, the corona discharge ignitor has various shapes and configurations, such as angular depressions or grooves, at the tip of the insulator. The shape and configuration of the tip provides a smaller radius which creates a more intensified electric field and provides better combustion.

Abstract: There is provided a spark plug 100 with a ground electrode 30, wherein a protrusion amount A of a protruding portion 36 satisfies a relationship of 0.4 mm?A?1.0 mm and wherein a width B from a front end surface 31 to a press recessed portion 37 satisfies a relationship of 0.4 mm?B?2.5 mm.

Abstract: A spark plug for internal-combustion engines includes a housing, an insulator, a center electrode, and an earth electrode. A gas guiding sections equipped with slopes that slope inwardly as they approach toward a tip side from a circumference surface of the housing and guide surfaces that are disposed on both sides in a circumferential direction of the slopes are formed in a tip part of the housing. The gas guiding sections are formed in the circumferential direction within a 90-degree range measured relative to the center of the earth joint section, which is a junction of the housing and the earth electrode, in the circumferential direction. When the spark plug is mounted to the engine, it is constituted so that the gas guiding sections are projected into a combustion chamber.

Abstract: An industrial spark plug (20) includes a central electrode (24) with a central base (30) formed of a nickel-based material and a central firing tip (32) formed of an iridium-based material. The central firing tip (32) has a tip thickness (tct) of 0.02 to 0.03 inches, a tip diameter (dct) of 0.1184 to 0.1776 inches, and an aspect ratio of 4.736 to 7.104. The central firing tip (32) is electron beam welded to the central base (30) to provide a robust joint therebetween. The central electron beam weld (36) includes a mixture of re-crystallized iridium-based material and re-crystallized nickel-based material extending continuously along and over the entire welding interface. The spark plug (20) also includes a ground electrode (26) with a ground firing tip (38) electron beam welded to a ground base (42).

Abstract: A method of manufacturing a center electrode for a spark plug, the method including the steps of: resistance welding a sphere of a noble metal to a center electrode of a spark plug to provide a center electrode with an electrode tip that has a tip portion of a first configuration, the first configuration having a first height and a first width; and shaping the tip portion after the sphere is welded to the center electrode by a process wherein the tip portion will have a second configuration having a second height and a second width, the second height being greater than the first height and the second width being less than the first width wherein a peripheral edge of the noble metal is flush with a peripheral edge of the material it is secured to.

Abstract: An electrode for a spark plug includes a contact portion. In a particular embodiment, the electrode further includes an annular base and a support portion formed from a different material than the contact portion. The contact portion may be aligned axially with a central axis of the annular base. Further, the contact portion is configured to shield the annular base and the support portion from a second electrode inserted into the annular base.

Abstract: A spark plug for use in an internal combustion engine. The spark plug is equipped with a metal shell, a ground electrode joined to the metal shell, and a center electrode disposed in the metal shell. The ground electrode has a protrusion formed on a top end thereof. The metal shell and the ground electrode are covered with a plated layer which has a thickness of 2 ?m to 18 ?m, which minimizes the possibility of peeling of the plated layer from the ground electrode while keeping the plated layer as thin as possible without sacrificing the resistance to corrosion on the ground electrode.

Abstract: A plasma jet ignition plug including an insulating body having an axial hole therethrough. A center electrode is inserted into the axial hole. A cavity portion is defined by the insulating body and center electrode, with the leading end of the axial hole as an opening end. A decreasing diameter portion decreasing in diameter toward a leading end side is formed on the axial hole, the leading end of the decreasing diameter portion is positioned closer to the leading end side than the leading end face of the center electrode. The inside diameter of the leading end of the decreasing diameter portion is made smaller than the outside diameter of the leading end face of the center electrode.

Abstract: A spark plug for an internal combustion engine has a center electrode, a ground electrode or both that includes an electrode material that is a Pt-based alloy. The electrode material may include platinum (Pt), at least one active element like aluminum (Al) or silicon (Si), and at least one high-melting point element such as ruthenium (Ru), iridium (Ir), tungsten (W), molybdenum (Mo), rhenium (Re), tantalum (Ta), niobium (Nb), chromium (Cr), or a combination thereof. In at least some of the disclosed alloys, the aluminum (Al) and/or silicon (Si) contributes to the formation of a thin protective oxide layer on a surface of the electrode material.

Abstract: A spark plug including: a center electrode; an insulator; a metal shell; a ground electrode; and an electrode chip. The electrode chip is joined to the ground electrode in a state in which the electrode chip is engaged in a recess portion formed in the ground electrode. The electrode chip is formed by previously welding a chip body portion containing a noble metal and a chip holding portion containing Ni before the electrode chip is joined to the ground electrode. A first molten bond is formed by welding the chip body portion and the chip holding portion. The first molten bond is placed in the recess portion so as not to be exposed to an outside environment in a state in which the electrode chip is engaged in the recess portion and joined to the ground electrode.

Abstract: A sparkplug includes an insulator having an axial hole, a center electrode of which a front end is placed further forwards than a front end of the insulator, and a shell. The center electrode has a shoulder portion and a main body portion and is made up of an outer layer and an inner layer. A front end face, which is connected to an outer circumferential surface of the insulator and the axial hole and slopes towards the rear end side, is formed at a front end portion of the insulator, and the front end of the insulator is placed further forwards than a boundary between the shoulder portion and the main body portion. A front end portion of the inner layer is placed further forwards than the boundary between the shoulder portion and the main body portion.

Abstract: A method of making a spark plug electrode includes several steps. One step includes providing an inner core of a ruthenium (Ru) based alloy or an iridium (Ir) based alloy. Another step includes providing an outer skin over a portion or more of the inner core in order to produce a core and skin assembly. The outer skin can be made of platinum (Pt), gold (Au), silver (Ag), nickel (Ni), or an alloy of one of these. Yet another step includes increasing the temperature of the core and skin assembly. And another step includes hot forming the core and skin assembly at the increased temperature.