Abstract: A spark plug has a firing pad attached to a center electrode or to a ground electrode. The firing pad is attached via laser welding and has a sparking surface with an overall fused area and an unfused area. In one or more embodiments, the overall fused area is located in part or more inboard of a peripheral edge of the firing pad.

Abstract: A spark plug is provided with a ground electrode, a noble metal tip made of a Pt alloy, and a relieving layer tip made of a Pt alloy which has a linear expansion coefficient between that of the ground electrode and that of the noble metal tip.

Abstract: A spark plug includes a center electrode extending along an axial line, a ground electrode, and a noble metal tip. A center axis of the noble metal tip is displaced from a center axis of the ground electrode toward a base-end side in the axial line. The ground electrode includes an outer layer and an inner layer, and a distal end of the inner layer is closer to the axial line than a base end of the ground electrode. An overlap area between the inner layer and the noble metal tip occupies a ratio of 25% or more in a projective plane defined by projecting, along the center axis, a plane of the ground electrode viewed from a distal-end face on a cross section of the ground electrode in which a maximum cross-sectional area of the inner layer is achieved, among cross sections orthogonal to the center axis.

Abstract: A spark ignition device, ground electrode therefor, and methods of construction thereof are provided. The spark ignition device includes a generally annular ceramic insulator with a metal shell surrounding at least a portion of the ceramic insulator. A center electrode is received at least in part in the ceramic insulator and a ground electrode extends from the shell to a free end portion. A firing tip is attached adjacent the free end portion of the ground electrode to provide a spark gap between the center electrode and the firing tip. The free end portion is at least partially bounded by at least one “as laser cut” peripheral side extending adjacent the firing tip.

Abstract: A spark plug for an internal combustion engine, the spark plug having: an elongated center electrode having a center electrode tip at one end and a terminal proximate the other end; an insulator substantially surrounding the center electrode, the insulator having a channel formed in an exterior surface of the insulator; an outer shell surrounding the insulator having: a jamb nut portion with a distal end extending thereform, the distal end being aligned with the channel such that the distal end of the outer shell is received within and engages the channel; a motor seat portion proximate to the jamb nut portion; and a threaded portion proximate to the motor seat portion, wherein the jamb nut portion, the motor seat portion, and the threaded portion are all integrally formed with the outer shell as a single component.

Abstract: A method of manufacturing a spark plug includes a joining step of joining a first member and a second member which constitute the spark plug. In the joining step, a first welding electrode in contact with the first member and a second welding electrode which has an elastically deformable intermediate portion and which is in contact with the second member are electrically connected through the first member and the second member, whereby the first member and the second member are joined together by resistance welding.

Abstract: A spark plug includes a center electrode, a ground electrode, and a noble metal tip. The noble metal tip is joined to an object member of at least one of two electrodes via a fusion zone. A projected overlap region of the noble metal tip and the fusion zone accounts for 70% or more of a projected region of the noble metal tip. The object member contains at least Si out of Al and Si such that the amount of Si is 0.4% by mass or higher and such that the total amount of Al and Si is 0.5% by mass. Multi-fusion spots exist on the surface of the fusion zone. Segments of a baseline which pass through the respective multi-fusion spots have a total length of a predetermined percentage of the length of the baseline. Joining strength to the noble metal tip can thereby be greatly improved when the member to be joined contains Si.

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 for an internal combustion engine has a cylindrical insulator, a center electrode held inside of the insulator, and, a terminal portion held inside of the insulator and electrically connected to the center electrode. The insulator has a insertion portion arranged closer to the base end side than the housing is, the insertion portion being inserted into a cylindrical plug cap. The insertion portion has a non-fit portion formed at the base end of the insulator, and, a fit portion formed to the head end side of the non-fit portion, an outer diameter of the non-fit portion being equal to or smaller than an inner diameter of the plug cap, the fit portion being fitted in the inner periphery surface of the plug cap.

Abstract: A direct spark igniter for a fuel-fired heating appliance is provided with enhanced ignition performance in environments having substantial levels of both moisture and pollution. Such enhanced ignition performance is representatively achieved by the combination of (1) forming external annular ribs on the ceramic body portion of the igniter; (2) extending a top end of the igniter electrode rod into the body portion; (3) bending the igniter electrode and ground rods and angling them toward one another; and (4) knurling external side surfaces on lower end portions of the igniter electrode and ground rods.

Abstract: [Objective] To provide a spark plug which is configured such that an insulation member, from which a center electrode projects, is pressed frontward and held in a metallic shell, and is fixed by means of crimping the rear end of the metallic shell, and which can prevent a drop in gas tightness between the metallic shell and the insulation member due to a difference in thermal expansion therebetween. [Means for Solution] In a spark plug in which a mating shaft portion (10) of an insulation member (1) is loose-fitted into a mating hole portion (30) of a metallic shell (21), a filler (41) for maintaining gas tightness is charged between the outer circumferential surface of the mating shaft portion (10) and the inner circumferential surface of the mating hole portion (30). Despite the thermal expansion difference, the gas tightness is maintained, because the filler (41) for maintaining gas tightness is charged between the inner and outer circumferential surfaces.

Abstract: An electrode material for use with spark plugs and other ignition devices. The electrode material is a two-phase composite material that includes a matrix component and a dispersed component embedded in the matrix component. In a preferred embodiment, the matrix component is a precious-metal based material and the dispersed component includes a material that exhibits a high melting point and a low work function such as, for example, carbides, nitrides, and/or intermetallics. A process for forming the electrode material into a spark plug electrode is also provided.

Abstract: A spark plug for use with internal combustion engines includes a metallic shell housing having a semi-cylindrical shroud partially surrounding the insulator and the center electrode and to which the ground electrode is joined. The semi-cylindrical shroud promotes improved heat dissipation from the ground electrode to the shell housing.

Abstract: A spark plug having a metal shell, the metal shell having a tool engagement portion, a trunk portion and a cylindrical groove disposed between the tool engagement portion and the trunk portion, wherein the following relationship is satisfied: Z1<=Z2, where “Z1” represents a section modulus of a first groove end of the groove, and where “Z2” represents a section modulus of a second groove end of the groove.

Abstract: A ground electrode (27) and a noble-metal chip (32) are joined via a weld portion (42) formed by fusing and mixing an Ni alloy and a Pt alloy. A plurality of acicular or rhizoid microcracks (51) are formed in the weld portion (42). As viewed on a section of the weld portion (42), the average length of the microcracks is 50 ?m to 500 ?m, and the average aspect ratio (shorter dimension/longer dimension) of the microcracks is 0.05 or less. At least one of the Ni alloy used to form the ground electrode (27) and the Pt alloy used to form the noble-metal chip (32) contains as an additive at least one of elements belonging to Groups 3A and 4A of the Periodic Table and oxides of these elements.

Abstract: Disclosed is a spark plug having an insulator with good breakage resistance. A spark plug 1 contains a ceramic insulator 2, a plate packing 22 and a metal shell 3. The ceramic insulator 2 has, on an outer circumferential surface thereof, a step portion 14, a leg portion 13 and a curved surface portion 31 between the step portion 14 and the leg portion 13. The metal shell 3 has, on an inner circumferential surface thereof, a taper portion 21. The ceramic insulator 2 is fixed in the metal shell 3 with the step portion 14 retained on the taper portion 21 via the plate packing 22. Herein, 50% or more of an inner circumferential edge portion IP of the plate packing 22 is in contact with a part of the ceramic insulator 2 located front of a middle region CP of the curved surface portion 31.

Abstract: A method for improving welding strength between a ground electrode and a noble metal tip on a spark plug. A fusion zone is formed along at least a portion of the boundary between the ground electrode and the noble metal tip through fusion of a portion of the ground electrode and a portion of the noble metal tip.

Abstract: A spark plug includes a ceramic insulator, a center electrode, a metallic shell, and a ground electrode. The center electrode has a shoulder portion at a forward end portion, which tapers forward with respect to the axial direction. A noble metal tip is joined to the forward end portion of the center electrode through a fusion zone. A spark discharge gap is formed between the noble metal tip and the ground electrode. The shortest distance between the fusion zone and a forward end surface of the noble metal tip is 0.8-1.2 mm. The outside diameter of the fusion zone as measured at a forward end of the fusion zone is smaller than that as measured at a rear end of the fusion zone. An acute angle ?1 formed by a straight line L1 and a straight line L2 satisfies the relational expression ?1?72°.

Abstract: The invention relates to an HF ignition device for igniting a fuel in an internal combustion engine with a corona discharge, comprising an ignition electrode, an insulating body on which the ignition electrode is mounted, the insulating body having a continuous channel in which an inner conductor leading to the ignition electrode is disposed, and an outer conductor which encloses the insulating body and, in combination with a section of the inner conductor, forms a capacitor, wherein the channel is filled with an electrically conductive filling material which encloses at least one conductor piece that forms at least one section of the inner conductor.

Abstract: A spark plug (20) for igniting a mixture of fuel and air of an internal combustion engine comprises a center electrode (22) and a ground electrode (24). At least one of the electrodes (22, 24) includes a body portion (28, 30) formed of thermally conductive material and a firing tip (32, 34) disposed on the body portion (28, 30). The firing tip (32, 34) includes a ceramic material, providing an exposed firing surface (36, 38). The ceramic material is an electrically conductive, monolithic ceramic material. Examples of preferred ceramic materials include titanium diboride, silicon carbide, ternary carbide, and ternary nitride. The ceramic material can also include oxides, borides, nitrides, carbides, silicides, or MAX phases.

Abstract: The invention describes a spark plug, which comprises an inner conductor, an insulator enclosing the inner conductor, a spark plug body enclosing the insulator and two electrodes forming a spark gap. The first electrode is a center electrode connected to the inner conductor in an electrically conductive manner and the second electrode is a ground electrode connected to the spark plug body in an electrically conductive manner. At least one of the electrodes has a precious metal region, adjoining the spark gap and consisting predominantly of platinum, iridium or an alloy of both and containing additionally at least one brittle metal. The precious metal region consists of a base material predominantly containing platinum and/or iridium, which comprises a coating with a brittle metal, which is more brittle than the base material.

Abstract: A spark plug including: a center electrode which extends in an axial direction; a cylindrical insulator which is disposed around an outer circumference of the center electrode; a cylindrical metal shell which is disposed around an outer circumference of the insulator; and a ground electrode having one end connected to the metal shell, and an end surface of the other end being positioned between the one end and the center electrode or on the center electrode, when viewed in the axial direction of the center electrode, wherein the end surface has a maximum width portion which is formed only at a position where a distance from a center position of the end surface is 12% to 88% of a distance from the center position to an outer side surface of the ground electrode.

Abstract: A spark plug includes a metallic shell, an insulator, a center electrode, a ground electrode, and a thin firing pad. The thin firing pad is made from a noble metal and can be attached to the center electrode, the ground electrode, or to both. In some examples, the thin firing pad possesses certain geometric properties and relationships that can improve ignitability and durability of the thin firing pad.

Abstract: A method of making an electrode material for use in a spark plug 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. The electrode material is a ruthenium-based material that includes a “fibrous” grain structure. The disclosed method includes hot-forming a ruthenium-based material into an elongated wire that includes the “fibrous” grain structure while intermittently annealing the ruthenium-based material as needed. The intermittent annealing is performed at a temperature that maintains the “fibrous” grain structure.

Abstract: A spark plug including a center electrode; an insulator; a metallic shell; and a ground electrode, wherein at least one of the center electrode and the ground electrode has thereon an intermediate member which connects the center electrode or the ground electrode to a noble metal tip. The intermediate member has a tip-bonding portion to which the noble metal tip is bonded, and an electrode-bonding portion which has a diameter greater than that of the tip-bonding portion, and which is bonded to the center electrode or the ground electrode. The intermediate member contains nickel (Ni) as a main component, and also contains chromium (Cr) in an amount of 15 to 25 wt. %. The intermediate member contains, in a surface portion thereof, silicon (Si) in an amount per unit volume of 0.04 mg/mm3 to 0.12 mg/mm3, and aluminum (Al) in an amount per unit volume of 0.03 mg/mm3 to 0.10 mg/mm3.

Abstract: Spark plug for an internal combustion engine, having a center electrode and a ground electrode arranged in radial direction around the center electrode, wherein an annular spark gap is formed between the center electrode and the ground electrode for igniting a fuel mixture by means of an electric ignition spark developing between the center electrode and the ground electrode, and wherein the ground electrode is contoured in such a way that particles reaching the region of the ground electrode can be removed from the spark gap under the influence of gravitational force.

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 which exhibits improved resistance to high-temperature oxidation of an electrode, and improved resistance to spark-induced erosion of, improved resistance to oxidation of, and improved joining reliability of a tip joined to the electrode. A spark plug has spark members; each of the spark members has a weight of 1.5 mg or more; and a center electrode and a ground electrode contain Ni as a main component, C in an amount of 0.005% by mass to 0.10% by mass, Si in an amount of 1.05% by mass to 3.0% by mass, Mn in an amount of 2.0% by mass or less, Cr in an amount of 20% by mass to 32% by mass, and Fe in an amount of 6% by mass to 16% by mass.

Abstract: A spark plug, comprised of: an insulator having an axial bore extending in the direction of an axis, a first inner circumferential surface extending at a forward side of the axial bore, a second inner circumferential surface extending at a rear side of the axial bore and having a diameter greater than that of the first inner circumferential surface, and a ledge connecting the first inner circumferential surface and the second inner circumferential surface; a center electrode having a head supported by the ledge and extending in a space surrounded by the second inner circumferential surface, and a circular columnar leg extending continuously from the forward end of the head in a space surrounded by the first inner circumferential surface; and a seal material for holding the center electrode in the axial bore.

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: Disclosed herein is a spark plug comprising an insulative sleeve. A glaze coating is disposed on the exterior surface of the insulative sleeve. The glaze coating comprises a silicate glass, a phosphorous glass, a borosilicate glass, or a combination of the foregoing glasses wherein the glasses are independently modified with a modifier selected from the group consisting of alkali group metals, alkali earth group metals, aluminum, and a combination of two or more of the foregoing modifiers and further wherein the glaze coating has a glass transition temperature (Tg) of 300 to 1000 degrees Celsius.

Abstract: It is an object of the present invention to provide a spark plug having a ground electrode joined securely by electric resistance welding. The spark plug includes a cylindrical metal shell and a ground electrode joined by electric resistance welding to an end portion of the metal shell. The metal shell has a high hardness region formed with a Vickers hardness of 3×102 to 5×102 Hv in the end portion thereof in such a manner that the high hardness region, when viewed in cross section along a plane including an axis of the spark plug and an axis of the ground electrode, has a length d of 0.3 to 0.8 mm from a ground electrode side welding boundary to a metal shell side welding boundary in a direction of load applied during the electric resistance welding.

Abstract: A spark plug includes a tubular insulator, a center electrode, a tubular metal shell, a ground electrode, and a pillar body tip. The tubular insulator has an axial hole penetrating in the direction of an axis. The pillar body tip includes one end face that is welded to the ground electrode and another end face that forms a gap with a front end portion of the center electrode. The ground electrode includes a part where the tip is to be welded. The surface forms a clearance with a part including a constituent material of the tip. The ground electrode includes a surface where a plating layer is disposed. The plating layer covers a surface excluding a formation part of the clearance. The clearance has a size A that is equal to or more than 0.01 mm and equal to or less than 0.5 mm.

Abstract: An 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. The electrode material is a metal composite and includes a particulate component embedded or dispersed within a matrix component such that the metal composite has a multi-phase microstructure. In one embodiment, the metal composite includes a matrix component that includes a precious metal and makes up about 2-80% wt of the overall composite and a particulate component that includes a ruthenium-based material and makes up about 20-98% wt of the overall composite.

Abstract: A spark plug includes at least one electrode having a sparking end. The sparking end is formed of a high temperature performance alloy including chromium in an amount of 10.0 weight percent to 60.0 weight percent, palladium in an amount of 0.5 weight percent to 10.0 weight percent, and a balance substantially of at least one of molybdenum and tungsten. The sparking end presents a spark contact surface, and at a temperature of at least 500° C., such as during use of the spark plug in an internal combustion engine, a layer of chromium oxide (Cr2O3) forms at said spark contact surface. The layer of Cr2O3 protects the bulk of the sparking end from the extreme conditions of the combustion chamber and prevents erosion, corrosion, and balling.

Abstract: A corner of a distal end of a ground-electrode-side noble metal tip of a spark plug is taken as a first corner; a corner of a leading end of a center-electrode-side noble metal tip is taken as a second corner; a corner formed at a starting point where a diameter of the center electrode is reduced is taken as a third corner; a corner of the ground electrode is taken as a fourth corner; a corner closest to the third corner of the corners on the distal end of the ground-electrode-side noble metal tip is taken as a fifth corner; a length of a virtual flying spark path defined between the first corner and the second corner is taken as L1; a length of a virtual flying spark path defined between the third corner and the fourth corner is taken as L2; a length of a virtual flying spark path defined between the third corner and the fifth corner is taken as L3; and L2 or L3, whichever is shorter, is taken as L4, the spark plug fulfills a relational expression of L4/L1?1.1.

Abstract: An 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. In one embodiment, the electrode material is a ruthenium-based material that includes ruthenium (Ru) as the single largest constituent on a wt % basis, and at least one of rhenium (Re) or tungsten (W). The electrode material may further include one or more precious metals and/or rare earth metals. The electrode material may be used to form the center electrode, the ground electrode, firing tips, or other firing tip components.

Abstract: A spark plug comprises an insulator having a axial hole penetrating in a direction of an axis, a central electrode provided on the front end side of the axial hole, a tubular metal shell that holds the insulator, and a ground electrode including a surface layer and a core material that is surrounded by the surface layer and has a larger thermal conductivity than that of the surface layer. The metal shell of the spark plug has a protruding portion in which at least a part of the metal shell protrudes toward the front end side in the direction of the axis. The ground electrode has an end surface at one end portion thereof joined to the inside of the protruding portion and the other end portion thereof facing the central electrode.

Abstract: A spark plug includes an insulator having an axial hole, a first inner circumferential surface, a second inner circumferential surface whose diameter is greater than that of the first inner circumferential surface, and a ledge portion connecting the first and the second inner circumferential surfaces. The spark plug also includes a center electrode having a large-diameter portion, a projection portion, and a circular columnar leg portion that projects into a space surrounded by the first inner circumferential surface. The spark plug includes a seal portion which fixes the center electrode within the axial hole. When C<A, A?C?B?A, where A represents a diameter of an imaginary cylinder having the minimum diameter required for surrounding the projection portion, B represents a maximum diameter of the large-diameter portion, and C represents an average diameter of the leg portion present in the space surrounded by the first inner circumferential surface.

Abstract: A spark plug includes a metallic shell, an insulator, a center electrode body, a ground electrode body, and a ground electrode tip. In one embodiment, the ground electrode tip includes a non-precious metal piece and a precious metal piece attached to each other. The non-precious metal piece has a side surface attached to a free end surface of the ground electrode body.

Abstract: A spark plug that is equipped with an insulator that has a stem portion on a front end side, a center electrode, and a main metal member that retains the insulator at an engaging projection portion, wherein an inner diameter DIN of the engaging projection portion, the maximum outer diameter dOUT of the stem portion, which faces an inner circumferential surface of the engaging projection portion, its inner diameter dIN, and dielectric constant ? of the insulator satisfy the condition of “(DIN?dOUT)/2?0.40 (mm)”, “(dOUT?dIN)/2?1.65 (mm)”, and “??9.4”.

Abstract: A plasma jet ignition plug including a wire-wound resistor for restraining the radiation of noise while allowing application of a sufficiently large current for generation of plasma to a spark discharge gap at the time of ignition. The wire-wound resistor having an inductance of 1 ?H to 100 ?H inclusive and a resistance of 1? or less, and is provided on at least one of a center electrode and a ground electrode. The wire-wound resistor restrains current which is generated by the influence of stray capacitance present in the plasma jet ignition plug, thereby reducing noise.

Abstract: A method is described for applying a pin made of a spark-erosion-resistant material, in particular of noble metal, onto a electrode base element. In order to achieve a large pin surface exposed to spark erosion, without increased material outlay for the pin, the pin is placed with one end surface onto the electrode base element and welded to it. The welded-on pin is then, by application of a compressive force engaging at the exposed end surface of the pin and directed toward the electrode base element, upset to a larger diameter.

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: What is described is a corona ignition device for igniting fuel in an internal combustion engine by generating a corona discharge, said corona ignition device comprising a housing, an insulator, which is held in the housing, a center electrode, which is held in the insulator, and at least one ignition tip at an and of the center electrode. The housing surrounds an interior, which has a cylindrical portion in which a cylindrical portion of the insulator sits. A widened interior portion adjoins at the end of the cylindrical interior portion remote from the ignition peak. The insulator has a thinner portion in the widened interior portion. The cylindrical portion of the insulator carries an electrically conductive coating, which ends before the thinner portion.

Abstract: A spark plug for an internal combustion engine is provided which is equipped with a tip protrusion disposed on a top of a hollow cylindrical housing of the spark plug. The spark plug also includes a center electrode retained in a porcelain insulator disposed inside the housing and a ground electrode is joined to the housing so as to form a spark gap. The tip protrusion serves to direct a flow of gas to be ignited by a spark produced in the spark gap and is shaped to have a radial width extending in a radial direction of the housing and a circumferential width extending in a circumferential direction of the cylindrical housing. The radial width is greater than the circumferential width. This enhances the efficiency in guiding the flow of gas toward the spark gap.

Abstract: An assembly for a spark plug, the assembly having: an insulator, the insulator having a channel formed in an exterior surface of the insulator; and a jamb nut surrounding the insulator, the jamb nut being aligned with the channel such that a distal end of the jamb nut does not contact the insulator.

Abstract: To provide a technology of improving the corrosion resistance of a spark plug. A spark plug having a metal shell on the outer surface of which a nickel plated layer is formed as a protective surface film. The nickel plated layer is such that when the atomic concentrations of constituent elements are measured in a depth direction by an X-ray photoelectron spectroscopy (XPS), the concentration of carbon atoms is 1.0% to 10.0% at a depth at which the atomic concentration of Ni elements is 80%.

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: The invention refers to a prechamber spark plug comprising an ignition electrode with several electrode arms. The ignition electrode is made of a cross-shaped blank that is cut out of sheet metal and then the electrode arms are set upright by bending. The sheet metal is made of iridium or an iridium-based alloy by rolling in a rolling direction and the ignition electrode blank is cut out in such a way that an angle of 50° or less is present between each of the electrode arms and the rolling direction (W).