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: 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 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 spark plug for an internal combustion engine, having an insulator including an insulator shoulder designed for mounting a tensioning nut or a housing and having a first outer diameter, an insulator head which is situated farther from the combustion chamber and adjoins the insulator shoulder, and which has a second outer diameter which is smaller than the first outer diameter, and a continuous cavity, a composition including a first contact composition, a second contact composition, and a composition resistor situated between the first contact composition and the second contact composition, a connecting pin which contacts the first contact composition, a center electrode which contacts the second contact composition, and a ground electrode. The connecting pin, the composition, and the center electrode are situated in the cavity, and the composition resistor has a third outer diameter, and a ratio of the third outer diameter to the second outer diameter is between 0.35 and 0.7.

Abstract: An ignition part (80) of a ground electrode (30) includes a fused part (85) in which construction materials of a base portion (82) and a noble metal member (81) are fused and mixed by performing laser welding on the two. In the fused part (85), an average ratio P of components originated from the noble metal member (81) at points K1, L1, and M1 is equal to or greater than 80%, and an average ratio Q of components originated from the base portion at points K3, L3, and M3 is equal to or higher than 20%, and P+Q is equal to or higher than 160%. Accordingly, it is possible to obtain joining strength in the parts in the ignition part (80), thereby sufficiently preventing the generation of cracks, separation, and the like due to thermal stress.

Abstract: A spark plug comprised of a spark plug main body and a cylindrical pressing member used for mounting the spark plug main body on an internal-combustion engine. The spark plug main body includes a cylindrical metal shell. A removing-tool engagement portion is formed on an outer circumferential face of the metal shell at a front end side of a caulking portion. The removing-tool engagement portion is used for engaging with a tool, when removing the spark plug main body from a plug hole of an internal-combustion engine.

Abstract: A precious metal tip on the side of a ground electrode is indirectly joined to the front end portion of the ground electrode via a mounting part interposed therebetween. The mounting part includes a base part and a protruding part. First, in the state where the precious metal tip is in contact with the protruding part, laser welding or the like is performed thereon to form a fused part and obtain a complex, and the base part is joined to a flat surface of the ground electrode by resistance welding. The grain size of grains of the mounting part in the vicinity of the of the fused part is greater than the grain size of the grain size of the grains thereof in the vicinity of the ground electrode, and the grain size of the grains of the flange part of the mounting part is smaller than the grain size of the grains of the protruding part.

Abstract: A spark plug casing includes a single-piece shell having a nut portion, first and second tubular portions and a converging shell portion, which are configured to be removed from a cylinder head as an integral device. The first tubular portion extends from the nut portion and has a first cross-sectional size. The second tubular portion has a second cross-sectional size less than the first cross-sectional size. The converging shell portion is coupled between the first and second tubular portions. The casing further includes a ground strap having a third cross-sectional size less than the second cross-sectional size. The ground strap is received within an end portion of the second tubular portion opposite the converging shell portion, such that the ground strap and the cylinder head are in a spaced relationship with respect to each other for preventing carbon buildup from binding the ground strap to the cylinder head.

Abstract: One of an electric wiring substrate and a retaining member includes a section having an absorptance with respect to a laser beam, and the other one of the electric wiring substrate and the retaining member includes a section having a transmittance with respect to the laser beam. The electric wiring substrate and the retaining member are welded to each other by irradiation with a laser beam. At this time, the electric wiring substrate and the retaining member are welded to each other at least at a part of an outer peripheral section of the electric wiring substrate.

Abstract: A spark plug with excellent vibration resistance performance and resistor load life-span characteristics, and a reduced diameter which is achieved by strengthening adhesion between a resistor and a conductive glass sealing layer.

Abstract: A side electrode for a spark plug is provided. The side electrode includes a side wire having a first end and a second end; an opening proximate to the first end, the opening extending from a first surface of the side wire to a second surface of the side wire, wherein the first surface has a flared portion proximate to the opening; and an electrode tip secured to the first end of the side wire, the electrode tip having a tip portion and a shaft portion, wherein the tip portion is located on the second surface and the shaft portion is secured to the side wire by engaging the flared portion.

Abstract: A spark plug is provided which can ensure gastightness between a metal shell and an insulator while preventing the cracking of the insulator. There is provided a spark plug in which a ledge portion 30 is formed on the metal shell 11 whose inside diameter is reduced gradually towards a front end portion, a step portion 32 is formed on an insulator 12 whose outside diameter is reduced gradually towards the front end portion and which confronts the ledge portion 30, and packing 34 is disposed between the ledge portion 30 and the step portion 32, characterized in that a distance between the ledge portion 30 and the step portion 32 gets narrower as the ledge portion 30 and the step portion 32 extend radially inwards, and in that an angle ? formed by the ledge portion 30 and the step portion 32 is one degree or larger and 10 degrees or smaller.

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 and method of manufacturing the same. The spark plug includes a tubular insulator holding a center electrode, and a tubular metallic shell holding the insulator. The insulator is inserted into the metallic shell from the rear end side thereof until a portion of the insulator engages the metallic shell. In this state, the circumferential edge of the rear end portion of the metallic shell is crimped, whereby the insulator is unitarily fixed to the metallic shell. A talc charged layer is formed in a clearance portion between the insulator and the metallic shell, and a wire packing is placed on a rear end portion of the talc charged layer for engaging the crimp portion. A portion of the talc charged layer is interposed between the wire packing and the rear trunk portion of the insulator.

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; and an outer shell surrounding the insulator, the outer shell having a jamb nut portion and a distal end extending from the jamb nut portion, the distal end of the outer shell is aligned with the channel such that the distal end of the outer shell is received in and engages the channel of the outer shell.

Abstract: The present invention provides a highly reliable spark plug used for an internal-combustion engine and including an insulator with a high withstand voltage, and a method for manufacturing the same. Namely, it provides a spark plug containing a cylindrical metal shell having an insulator holding hole, a cylindrical insulator including an axial hole therein which extends in an axial direction, and engaging with said insulator holding hole of said metal shell, and a center electrode held in said axial hole of said insulator, wherein said insulator has a texture in which one or more pores exposed in a judgment area with 50 ?m in diameter occupy 40% or less of said judgment area at any locations in an observation area, in the case where a predetermined mirror-finishing section of an enclosed portion surrounded by said metal shell is used as said observation area to observe pores exposed in said observation.

Abstract: When an insulator of a spark plug receives an external force in a bending direction perpendicular to an axis at a rear end side body portion, a position C where the insulator is supported by a crimping portion via a packing acts as a fulcrum, and a stress is applied between the position C and a position B where the insulator is supported by a ledge portion via a packing. When an insulator is designed in which the balance of size and modulus of section is adjusted so that ?A which denotes a proof strength against bending between a rear end position A of the insulator and the position C and ?B which denotes a proof strength against bending between the position B and the position C satisfy 0.71??A/?B?1.27, cracks can be prevented.

Abstract: An object of the invention is to restrain separation of an electrode tip from a ground electrode or from a center electrode. A spark plug satisfies a condition 0.8?A1/A2?1.9, where, as viewed on a section which contains a center axis (O) of an electrode tip, A1 [Hv] is hardness of the electrode tip as measured outside a circle having a radius of 0.2 mm, with a boundary point (PA) on a surface of the spark plug between a fusion zone and the electrode tip serving as the center of the circle, and A2 [Hv] is hardness of the electrode tip as measured within the circle having a radius of 0.2 mm.

Abstract: A spark plug (100) including a noble metal tip (80) disposed on a distal end portion (31) of a ground electrode (30). The noble metal tip (80) is joined to the top surface of an intermediate member (81), which is a member separate from the ground electrode (30). The bottom surface of the intermediate member (81) is joined to the ground electrode (30), whereby the noble metal tip (80) is fixed to the ground electrode (30). The intermediate member (81) is formed such that its average hardness is higher than the average hardness of a portion of the ground electrode (30), excluding an intermediate portion (33) to be bent.

Abstract: A spark plug includes a center electrode extending in an axial direction; an insulator formed externally of the outer circumference of the center electrode; a metallic shell formed externally of the outer circumference of the insulator and having a ledge which supports the insulator; and a ground electrode joined to the metallic shell. The insulator has a support portion which faces the ledge. A “frontward direction” is defined as the direction parallel to the axial direction toward a spark portion formed between the center electrode and the ground electrode. The insulator has a diameter reduction portion whose outside diameter reduces along the frontward direction from the support portion, and a diameter increase portion whose outside diameter increases along the frontward direction from the front end of the diameter reduction portion. This restrains the generation of leak current while maintaining heat resistance of the spark plug.

Abstract: A spark plug for an internal combustion engine, includes: a cylindrical insulating body; a center electrode; a cylindrical metal shell; and a ground electrode, as defined herein, wherein the noble metal tip is bonded to the ground electrode via a molten bond, and when viewed in a cross-section including a center axis of the noble metal tip along a longitudinal direction of the ground electrode, a sum of a cross-sectional area of a base-end-side molten bond (A) positioned at a base end side of the ground electrode and a cross-sectional area of a front-end-side molten bond (B) positioned at a front end side of the ground electrode is equal to or greater than 4 mm2, and the cross-sectional area of the front-end-side molten bond (B) is 1.1 to 1.3 times greater than that of the base-end-side molten bond (A).

Abstract: A spark plug for a motor vehicle internal combustion engine, substantially elongated in shape, and including: two coaxial electrodes of an inner central electrode and an outer base electrode enclosing the central electrode; and an electrically insulating annular block, interposed between the central electrode and the base electrode and including an annular shoulder. The insulating annual block includes an annular groove located at the shoulder.

Abstract: A spark plug casing includes a single-piece shell having a nut portion, first and second tubular portions and a converging shell portion, which are configured to be removed from a cylinder head as an integral device. The first tubular portion extends from the nut portion and has a first cross-sectional size. The second tubular portion has a second cross-sectional size less than the first cross-sectional size. The converging shell portion is coupled between the first and second tubular portions. The casing further includes a ground strap having a third cross-sectional size less than the second cross-sectional size. The ground strap is received within an end portion of the second tubular portion opposite the converging shell portion, such that the ground strap and the cylinder head are in a spaced relationship with respect to each other for preventing carbon buildup from binding the ground strap to the cylinder head.

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 to another end of the center electrode; an insulator surrounding a portion of the center electrode, 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: 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 to another end of the center electrode; an insulator surrounding a portion of the center electrode, 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: An ignition device for an internal combustion engine and method of construction therefore includes a housing with an insulator secured therein. A center electrode is mounted within the insulator. A ground electrode extends from the housing with a portion of the ground electrode defining a spark gap across from the center electrode. The center electrode has a firing tip, wherein a resistance weld joint initially bonds the firing tip to the center electrode and a continuous bead of overlapping first weld pools formed substantially from the material of the firing tip further bonds the firing tip to the electrode. A continuous bead of overlapping second weld pools formed radially outwardly from the first weld pools forms a rounded shoulder surface extending from the first weld pools to an outer surface of the center electrode.

Abstract: A spark plug (1) for an internal combustion engine includes: a cylindrical insulator (2) having an axial hole (4) penetrating in a direction of an axis (C1); a center electrode (5) partially inserted in the axial hole (4); a metal shell (3) surrounding an outer periphery of the insulator (2) and which is fixed to the insulator (2) by means of a crimped portion (20) provided at a rear end portion of the metal shell (3); and a ground electrode (27) joined to the metal shell (3) such that a portion of the ground electrode (27) opposes a leading end portion of the center electrode (5) via a spark discharge gap (33), wherein the insulator (2) has an annular groove portion (23) which opposes an inner edge of the crimped portion (20).

Abstract: A spark plug is provided which can ensure gastightness between a metal shell and an insulator while preventing the cracking of the insulator. There is provided a spark plug in which a ledge portion 30 is formed on the metal shell 11 whose inside diameter is reduced gradually towards a front end portion, a step portion 32 is formed on an insulator 12 whose outside diameter is reduced gradually towards the front end portion and which confronts the ledge portion 30, and packing 34 is disposed between the ledge portion 30 and the step portion 32, characterized in that a distance between the ledge portion 30 and the step portion 32 gets narrower as the ledge portion 30 and the step portion 32 extend radially inwards, and in that an angle ? formed by the ledge portion 30 and the step portion 32 is one degree or larger and 10 degrees or smaller.

Abstract: A spark plug for an internal combustion engine comprises 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, and a ground shield. The insulator has a substantially cylindrical body with at least a first insulator section and a second insulator section. The first and second insulator sections having first and second diameters respectively and are separated by an insulator shoulder. The ground shield has an elongated base section substantially surrounding the first insulator section, a frustoconical flange protruding from one end of the base section to engage the insulator shoulder, and a ground electrode extending from the other end of the base section to define an axial spark gap with respect to the center electrode tip. The base section and the ground electrode are formed as separate components and secured together to form the ground shield.

Abstract: A spark plug having a multilayer firing tip that minimizes the amount of precious metal used and a method of assembling a spark plug with a multilayer firing tip. The firing tip includes a discharge end and a weld end, with the weld end being connected to a center electrode, and more specifically to a base electrode on the center electrode. The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode. More specifically, the weld end has a coefficient of thermal expansion which is greater than the coefficients of thermal expansion for the discharge end and base electrode. The weld end is formed from Nickel and Chromium with a limited amount of additional elements. The spark plug is assembled by providing a first elongated material formed from the material used for the discharge end and a second elongated material formed from a material used for the weld end.

Abstract: A spark plug including: a center electrode including an electrode base member and a core member; an electrode tip joined to the center electrode via a molten bond; an insulator holding the center electrode; a metal shell holding the insulator; and a ground electrode joined to the metal shell. Relationships d?2.1 [mm] and ?0.09×d+0.33<Vb/(Va+Vb)<?0.2×d+0.75 are satisfied, where d is an outer diameter of the center electrode at a position 4 mm closer to the base end of the center electrode from the base end of the molten bond in the axial direction, and Va and Vb are volumes of the electrode base member and the core member, respectively, at a region between the base end of the molten bond and the position in the axial direction.

Abstract: A spark plug including an insulator and a metallic shell having an outer surface and an inner surface. The outer surface has a taper portion which comes into contact with a peripheral region around a mounting hole of an internal combustion engine, a tool engagement portion, and a trunk portion formed between the tool engagement portion and the taper portion. The inner surface has an annular step portion projecting toward the insulator and an internal trunk portion extending from the base of the step portion toward the rear end of the metallic shell. When the insulator and the metallic shell are fixed to each other by one of either cold and hot crimping, the projected area of the taper portion is at least two times or at least 1.5 times that of the step portion, respectively.

Abstract: A spark plug and method of manufacturing the same. The spark plug includes a tubular insulator holding a center electrode, and a tubular metallic shell holding the insulator. The insulator is inserted into the metallic shell from the rear end side thereof until a portion of the insulator engages the metallic shell. In this state, the circumferential edge of the rear end portion of the metallic shell is crimped, whereby the insulator is unitarily fixed to the metallic shell. A talc charged layer is formed in a clearance portion between the insulator and the metallic shell, and a wire packing is placed on a rear end portion of the talc charged layer for engaging the crimp portion. A portion of the talc charged layer is interposed between the wire packing and the rear trunk portion of the insulator.

Abstract: A spark plug for an internal combustion engine is provided which includes a hollow cylindrical metal shell with an open end portion to be exposed to a combustion chamber of the engine, a ground electrode joined to the metal shell, a center electrode disposed in the metal housing to define a spark gap between itself and the ground electrode. The spark plug also includes a stream shaper geometrically formed on an inner periphery of the open end portion of the metal shell to shape tumble vortexes of air-fuel mixture into vortex streams oriented toward a central portion of the combustion chamber. This ensures the stability of orientation of the tumble vortexes to control a flow of sparks, thereby enhancing the ignitability of the air-fuel mixture in the combustion chamber.

Abstract: When an insulator of a spark plug receives an external force in a bending direction perpendicular to an axis at a rear end side body portion, a position C where the insulator is supported by a crimping portion via a packing acts as a fulcrum, and a stress is applied between the position C and a position B where the insulator is supported by a ledge portion via a packing. When an insulator is designed in which the balance of size and modulus of section is adjusted so that ?A which denotes a proof strength against bending between a rear end position A of the insulator and the position C and ?B which denotes a proof strength against bending between the position B and the position C satisfy 0.71??A/?B?1.27, cracks can be prevented.

Abstract: A spark plug for an internal-combustion engine is provided wherein the central and ground electrodes exhibit a long service life and wherein the fatigue strength at high temperatures is improved. The ground electrode is made from an alloy comprised of nickel (Ni) as a primary component, chromium: 20-30% by weight, iron: 7-20% by weight, aluminum: 1-3% by weight, titanium: 0.05-0.5% by weight, manganese: not higher than 0.1% by weight, silicon: not higher than 0.1% by weight, and carbon: not higher than 0.5% by weight. The alloy further includes at least one specific element selected from zirconium, yttrium, neodymium, cerium, lanthanum and samarium. Further, the total content of the specific element group is 5% or more of the aluminum content and is not higher than 1% by weight.

Abstract: A spark plug in which a distal end portion (60) of a crimp portion (53) of a metallic shell (50) is crimped by bending the distal end portion inward, whereby the metallic shell (50) and an insulator (10) are fixed together with a first packing (6), a second packing (7), and talc (9) being present therebetween. The first packing (6) assumes an annular shape and has a circular cross section. A minimum diameter portion of the crimp portion (53), which portion is closest to the outer circumferential surface (17) of a trunk portion (18), is located at the position of the center line of the first packing (6) or inward thereof with respect to the axis O. The crimp portion (53) does not come into contact with the insulator (10), and the first packing (6) comes into contact with the insulator (10). Furthermore, the first packing (6) has a hardness that is lower than that of the crimp portion (53).

Abstract: A plasma jet spark plug and a manufacturing method therefor are disclosed. In a state in which a noble-metal chip having a flange-like outwardly projecting portion is disposed in a communication section of a ground electrode, an electrode base metal of the ground electrode is disposed in a stepped engagement portion of a metallic shell, which retains an insulator therein. While being pressed against a front end portion of the insulator, the noble-metal chip is joined to the electrode base metal, whereby a clearance between the ground electrode (electrode base metal) and the front end portion of the insulator can be closed. Therefore, energy of plasma generated within the cavity does not leak.

Abstract: A spark plug for igniting gases in an internal combustion engine is disclosed. The spark plug has a center electrode, an insulator, a one-piece shell, and a terminal. The center electrode is in communication with an energy source. The insulator surrounds the center electrode. The one-piece shell surrounds and contacts the insulator for securing the insulator within the shell, wherein the shell has a plurality of threads near a first end and a ground electrode attached to the shell and aligned with a tip of the center electrode at a second end to define a spark gap. Further, a seat is formed in the shell between the plurality of threads and the ground electrode for sealing the shell against the engine. The terminal has a first end in communication with the center electrode and a second end which has a connector portion for connecting to the energy source.

Abstract: An extension-type spark plug (10) is disclosed for igniting the air-fuel mixture in an internal combustion engine. The spark plug (10) includes an installation conduit (12), a contact button (34), an electrode extension (20), a firing electrode (60), a ground plate (66), a sleeve insulator (22), an upper insulator (90) and a lower insulator (50). The electrode extension (20) is axially aligned with and in communication with the firing electrode (60). The ground plate (66) is proximate the firing electrode (60) to define a spark gap between the firing electrode (60) and a first end of the ground plate (66). The sleeve insulator (22) surrounds the electrode extension (20). The upper insulator (90) surrounds an upper portion of the electrode extension (20) and is in contact with the sleeve insulator (22). The lower insulator (50) surrounds the lower portion of the electrode extension (20) and is in contact with the sleeve insulator (22).

Abstract: A spark plug comprising: an insulator shell; a center electrode inside the insulator shell such that one end of the center electrode protrudes from the insulator shell; a metal shell exterior to the insulator shell; a side ground electrode having one end coupled to the metal shell and the other end facing the protruding end of the center electrode to form a spark discharge gap between the center electrode and the side ground electrode; and a metal tip on at least one of the side ground electrode or the center electrode, located at the spark discharge gap, that is a platinum-based alloy including 23-35 weight percent palladium, greater than 0 to 10 weight percent iridium and the balance being platinum.

Abstract: A spark plug in which a glaze is applied to a rear trunk portion (245), a shoulder portion (240), and a portion of a intermediate diameter portion (230) of an insulator (200), and glaze firing is performed. Even when the glaze (shown by dots in the drawings) softened by heating flows downwards, the glaze is accommodated within a groove portion (235) formed between the shoulder portion (240) and the maximum diameter portion (210), and does not reach the maximum diameter portion (210). Such structure facilitates assembly of the insulator (200) to a metallic shell in a spark plug manufacturing process.

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: An object of the present invention is to provide a spark plug which has more excellent impact resistance with electrical conductivity and airtightness kept excellent. In the invention, each of first and second electrically conductive sealing layers (17) and (19) is made of electrically conductive glass containing a glass component and a metal component. The metal component at least contains a Cu—Zn alloy which contains Cu as a first component, and Zn as a second component.

Abstract: An improved structure of a spark plug is provided to ensure a high strength of joint between a ground electrode and a metal shell. The ground electrode is resistance-welded to the metal shell so that it is embedded partially in an end surface of the metal shell to create a weld interface extending from the end surface to an inner periphery of the metal shell, thus resulting in an increased size of the weld interface to increase the joint strength. The resistance welding keeps the temperature of a weld between the ground electrode and the metal shell at a lower level during welding as compared with laser welding, thus minimizing solidification cracking in the weld.

Abstract: A spark plug having a multilayer firing tip that minimizes the amount of precious metal used and a method of assembling a spark plug with a multilayer firing tip. The firing tip includes a discharge end and a weld end, with the weld end being connected to a center electrode, and more specifically to a base electrode on the center electrode. The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode. More specifically, the weld end has a coefficient of thermal expansion which is greater than the coefficients of thermal expansion for the discharge end and base electrode. The weld end is formed from Nickel and Chromium with a limited amount of additional elements. The spark plug is assembled by providing a first elongated material formed from the material used for the discharge end and a second elongated material formed from a material used for the weld end.

Abstract: A spark plug having a multilayer firing tip that minimizes the amount of precious metal used and a method of assembling a spark plug with a multilayer firing tip. The firing tip includes a discharge end and a weld end, with the weld end being connected to a center electrode, and more specifically to a base electrode on the center electrode. The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode. More specifically, the weld end has a coefficient of thermal expansion which is greater than the coefficients of thermal expansion for the discharge end and base electrode. The weld end is formed from Nickel and Chromium with a limited amount of additional elements. The spark plug is assembled by providing a first elongated material formed from the material used for the discharge end and a second elongated material formed from a material used for the weld end.

Abstract: A spark plug assembly (22) includes a center electrode (34) having a high performance metal sleeve (50) attached at its sparking end. The sleeve (50) is fitted to a tenon on the end of the center electrode (34) and fixed in place by a weld line (58) produced by laser beam pulses (56). The weld line (58) is applied by overlapping a plurality of spaced-apart beads in a single, continuous circumscribing line. The sleeve (50) is permitted to expand and contract under the influence of thermal cycling without constraint except for the fixation weld line (58). Therefore, the sleeve (50) does not experience stress build-ups resulting from differing rates of thermal expansion relative to the center electrode (34), which is preferably made from a nickel or other composition dissimilar to that of the high performance metal sleeve (50). Various ground electrode (30, 60) configurations are possible.

Abstract: A spark plug is provided with a metal shell and a ceramic insulator to support therein a center electrode. The ceramic insulator includes a front portion with a stepped outer surface, a middle portion, a rear portion and a shoulder portion defined between the middle and rear portions. A difference between the outer diameters of the middle and rear portions of the ceramic insulator is 1.8 mm or smaller. The metal shell includes a radially inward protrusion to retain thereon the stepped outer surface of the ceramic insulator and a rear end portion crimped onto the shoulder portion of the ceramic insulator. An inner circumferential surface of the crimped shell portion has a region held in contact with the insulator shoulder portion with a radially innermost point of the crimped shell portion being spaced radially apart from the ceramic insulator and axially apart from the insulator shoulder portion.

Abstract: A spark plug (1) for an internal combustion engine includes: a cylindrical insulator (2) having an axial hole (4) penetrating in a direction of an axis (C1); a center electrode (5) partially inserted in the axial hole (4); a metal shell (3) surrounding an outer periphery of the insulator (2) and which is fixed to the insulator (2) by means of a crimped portion (20) provided at a rear end portion of the metal shell (3); and a ground electrode (27) joined to the metal shell (3) such that a portion of the ground electrode (27) opposes a leading end portion of the center electrode (5) via a spark discharge gap (33), wherein the insulator (2) has an annular groove portion (23) which opposes an inner edge of the crimped portion (20).