Abstract: A method of producing an electrode support for a spark plug is provided. The method includes providing the electrode support. The method includes brazing a chip to the electrode support.

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: A spark plug includes a ground electrode. The cross sectional area S of a ground electrode base member of the ground electrode satisfies a relation 1.8 mm2?S?3.2 mm2. The embedment depth A of a noble metal tip embedded in a second base member surface and the tip thickness B of the noble metal tip measured along the direction in which the noble metal tip is embedded in the second base member surface satisfy a relation 0.4?(A/B)?0.8.

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 method and an apparatus for manufacturing a spark plug. A bending apparatus includes a bending unit having a preliminary bending unit and a main bending unit, and a gap adjusting unit. The main bending unit including pressing unit for pressing a distal end of a ground electrode toward a center electrode, and a gap adjusting unit configured to adjust a relative height position of the distal end of the ground electrode relative to a distal end of the center electrode in an axis line direction. The gap adjusting unit includes a gap adjusting unit for relatively moving the distal end of the ground electrode relative to the center electrode in a direction substantially perpendicular to the axis line direction, and a restricting unit for restricting relative movement of the distal end of the ground electrode relative to the center electrode in the axis direction.

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 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: The ignitability of a spark plug configured without a noble metal for a center electrode and a ground electrode is improved. The spark plug comprises a center electrode, an insulator, a metal shell, and a ground electrode including a discharge surface. The ground electrode forms a spark gap between the discharge surface and the center electrode. The center electrode and the ground electrode both do not include a noble metal. The ground electrode comprises a proximal end portion combined with the metal shell and positioned above, the discharge surface and a distal end portion including the discharge surface and positioned below the proximal end portion while continued from the proximal end portion. A width Da of the center electrode viewed from a first direction and a width Db of the proximal end portion viewed from the first direction satisfy Db/Da?0.92. The first direction is perpendicular to the axial direction and directing from the proximal end portion to the center electrode.

Abstract: A spark plug include an insulator, a central electrode, which is in the form of a bar received in the insulator, a metal case, which surrounds the insulator and is grounded, and a ground elbow fixed to the metal case. The central electrode includes a discharge terminal exposed outside the insulator and defining an extension line as an imaginary line extending from the discharge terminal along a central axis of the central electrode. The ground elbow has a connection end and an opposite, sharp-tip-like receiving end. The connection end is fixed to the metal case. The receiving end is set close to but spaced from the discharge terminal and is locate by one side of the extension line.

Abstract: Peeling resistance of a noble metal chip is improved by reducing a difference in the thermal stress generated between the noble metal chip and a ground electrode. A spark plug 1 includes an insulator 2, a center electrode 5, a metal shell 3, and a ground electrode 27, wherein a spark discharge gap 33 is formed between the center electrode 5 and the noble metal chip 41 bonded to the ground electrode 27. The ground electrode 27 is provided with a concave hole portion 43, and 70% or more of the noble metal chip 41 is bonded to the hole portion 43 of the ground electrode 27 through a fusion portion 35 formed by fusing the noble metal chip and the ground electrode 27 to each other by emitting a laser beam or the like from the side surface of the noble metal chip. A gap 45 is formed between the noble metal chip 41 and at least a part of an inner wall surface 43 S of the hole portion 43 so as to be more than 0 mm and equal to or less than 1.

Abstract: An ignition plug that maintains excellent ignition performance over a long period of time through effective prevention of channeling. The ignition plug includes an insulator having an axial bore, a center electrode inserted into the axial bore, a metallic shell disposed externally of the outer circumference of the insulator, and a ground electrode fixed to a front end portion of the metallic shell. A cavity is defined by the wall surface of the axial bore and the front end surface of the center electrode. The ground electrode includes a body whose distal end portion is disposed away from the front end of the insulator, and a protrusion protruding from the body.

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 plasma jet spark plug for igniting an air-fuel mixture in a conventional combustion device such as an internal combustion engine.

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 press recessed portion 37 extends to a front end surface 31 of the ground electrode 30.

Abstract: A spark plug in which the center electrode is formed by laser welding along the circumference of a joint surface between a center electrode base metal and a noble metal tip in excess of full circumference. When G represents a spark gap and A represents a shortest gap between a laser weld bead and a line drawn parallel with axis X, A?3G. Straight lines S1 and S2 which connect the center of the noble metal tip 1 and the circumferential center of a proximal end 52 of the ground electrode 51 and vertex 8 of a protrusion 7 formed at a final end portion 6e of a bead 6 formed by circumferential laser welding, respectively, form an angle ? of 45 degrees. Since the protrusion 7 of the bead is the angle ? away from the ground electrode 51, an abnormal discharge is unlikely to be generated.

Abstract: A center electrode includes a tapered electrode base member mount and a noble metal tip joined to the electrode base member mount via a fused portion in which the component of the noble metal tip and the component of the electrode base member mount are fused. In this state, the cross section area S1 at a tip side boundary between the fused portion and the noble metal tip and the cross section area S2 at a base member side boundary between the fused portion and the electrode base member mount satisfy the relational expression of S1<S2. Regarding the cross section area S3 at the base portion of the electrode base member mount, (S3?S2)/D satisfies the relational expression of 5?(S3?S2)/D?50. D is the shortest distance in the axis line direction from the base member side boundary to the base portion.

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: A spark plug has a central electrode and a plurality of peripheral electrodes. The central electrode has a proximal portion and a distal portion. The distal portion of the central electrode has a circular cross-section with a longitudinal axis and terminates in a distal end. Each peripheral electrode has a lower portion and an upper portion. Each upper portion has a distal-most point. Each distal-most point is disposed in a central plane within which the longitudinal axis of the distal portion of the central electrode is wholly disposed. The cross-section of each upper portion taken along its central plane defines a convex outer side and a non-convex inner side. Each convex outer side has a curved surface which is tangent to a plurality of tangent planes, all of which intersect the longitudinal axis of the distal portion of the central electrode at points at or above the distal end of the distal point of the central electrode.

Abstract: A spark plug having a ground electrode that includes a press-formed recess portion comprised of a first portion with which a working pin has come into contact, and a second portion with which the working pin has not come into contact. A relation B1/B2?0.05 is satisfied, where B1 represents the depth of the second portion, and B2 represents the depth of the press-formed recess portion.

Abstract: A spark plug 100 comprised of a metal shell 1, an insulator 2, a center electrode 3 and a ground electrode 4. A rear-end face of the ground electrode 4 is welded to a front-end face of the metal shell 1, and a bent portion 5 located at the intermediated position in the longitudinal direction is bent toward the center of the spark plug 100. The ground electrode 4 assumes a circular-shape with a diameter of 2 mm or less whereby an inflow of an air-fuel mixture is not disturbed even when the air-fuel mixture directly flows into a back face of the ground electrode 4. The ground electrode 4 is comprised of an outer layer 4A made of a nickel alloy and an inner layer 4B made of pure copper with an excellent thermal conductivity, in which a ratio of a cross-sectional area of the inner layer 4B to the entire cross-sectional area of the ground electrode 4 is 10% or more to 35% or less.

Abstract: Exemplary embodiments of the present invention provide a spark plug for use in conjunction with an internal combustion engine, and, more particularly, to a spark plug having a structure providing improved ignition capability. In one particular configuration, a spark plug is provided forming a gap between a center electrode and an insulator of the spark plug. However, it will become apparent that other configurations are contemplated as well, as shown and described herein.

Abstract: A spark plug (100) including a center electrode (130) and a ground electrode (140), which is formed by joining a ground electrode chip (143) to a ground electrode base material (141) via an intermediate member (142). A method for producing the spark plug (100) includes providing a projecting portion (142p) on the intermediate member (142), and projection-welding the intermediate member (142) to the ground electrode base material (141) by means of the projecting portion (142p), to thereby join the intermediate member 142 to the ground electrode base material (141). Further, the intermediate member (142) of the spark plug (100) includes a cylindrical columnar portion (142e) which is joined to the ground electrode chip (143), and a flange portion (142d) which is joined to the ground electrode base material (141) and which flange portion (142d) has a diameter greater than that of the cylindrical columnar portion (142e).

Abstract: There is provided a spark section (80) of needle-like shape protruding from an inner surface (33) of a ground electrode (30) to define a spark gap between the spark section and an electrode tip on a center electrode. The spark section (80) has a noble metal member (81) and an intermediate member (86) joined to each other. The materials of the noble metal member (81) and the intermediate member (86) are selected in such a manner that the thermal conductivity of the intermediate member (86) is lower than that of the noble metal member (81). This limits heat radiation through the heat radiation passage from the noble metal member (81) through the intermediate member (86) to the ground electrode (30) so as to maintain the noble metal member (81) at a higher temperature than conventional types and reduce a quenching effect of the noble metal member (81) on a flame core generated in the spark gap for improvement in ignition performance.

Abstract: A spark plug including: a ground electrode including a thick portion provided on a base end side, a thin portion provided on a distal end side, and a stepped portion provided on an inner peripheral surface between the thick portion and the thin portion; a noble metal tip partially embedded in an inner peripheral surface of the thin portion; and a bulge portion provided on the inner peripheral surface of the thin portion between the stepped portion and the noble metal tip. When viewed from a side surface of the ground electrode, a relationship [a protruding height of the noble metal tip from the inner peripheral surface of the thin portion]?[a protruding height of the bulge portion from the inner peripheral surface of the thin portion].

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 device for inspecting a spark plug insulator for bending, the spark plug insulator including a cylindrical body having a radially enlarged flange at an axially intermediate portion thereof, and a through hole formed in the body along an axial direction of the body. The inspection device includes an insulator supporting means for supporting the spark plug insulator so as to be slidable in an axial direction of the spark plug insulator, a linear inspection pin that is to be inserted into the through hole of the spark plug insulator supported by the insulator supporting means, and a detecting means for detecting a sliding movement of the spark plug insulator when the spark plug insulator is caused to slide in the axial direction thereof by the inspection pin by the inspection pin prevented from completely penetrating the through hole of the spark plug insulator owing to bending of the spark plug insulator which exceeds a predetermined tolerance.

Abstract: A spark plug capable of preventing breakage of a ground electrode. The spark plug is comprised of a ground electrode having a base end portion fixed to a metal shell, a bend portion integrally formed with the base end portion and being bent and a front end portion integrally formed with the bend portion and forming a spark discharge gap “g” with a center electrode. The ground electrode is comprised of a core extending from the base end portion towards the front end portion through the bend portion; and an outer layer disposed outside the core and extending from the base end portion up to the front end portion through the bend portion. The core is made of Hastelloy C serving as a first metal, and the outer layer is made of Inconel 601 serving as a second metal. Hardness of Hastelloy C is higher than that of Inconel 601.

Abstract: An internal combustion engine radio frequency spark plug including two plasma-generating electrodes, separated by an insulator, that constitute respectively an outer shell enclosing the insulator and a central electrode housed in a central bore of the insulator. The spark plug includes a deep opening over the entire circumference of the shell, forming a heat-exchanger chamber inside the spark plug shell, opening outwards.

Abstract: A spark plug is disclosed as having a metal shell, a porcelain insulator fixedly secured to the metal shell, a center electrode and a ground electrode providing a spark discharge gap with the center electrode. The porcelain insulator has a through-bore partially exposed from an end face of the ground electrode in a surface area S1, as viewed from a distal end of the spark plug, and having a total surface area S2 falling in the relationship S1/S2?0.3. The center electrode protrudes from the porcelain insulator with a protruding length L under the relationship L?0.6 mm. A minimal value Hmin and a maximal value Hmax in distance between the ground electrode and the end face of the porcelain insulator lies in the relationship Hmax/Hmin?1.3. Wall thickness T between the through-bore and an outer periphery of the porcelain insulator lies in the relationship T?0.7 mm.

Abstract: A spark plug, including a central electrode, a first ground electrode, which is situated in a curved shape having a horizontal area and an essentially vertical area, and at least one second ground electrode, which is situated adjacent to the central electrode in such a way that a distance between the first ground electrode and the central electrode is less than a distance between the second ground electrode and the central electrode.

Abstract: A sparkplug having ground and/or center electrodes that include a firing tip formed by reflowing of an end of wire having an opposite end carried by a feed mechanism. The present invention also includes methods of manufacturing an ignition device and electrodes therefore having a firing tip, including providing a metal electrode having a firing tip region; providing a wire having a free end and another end carried by a feed mechanism; and reflowing the free end to form a firing tip.

Abstract: A spark plug including: a center electrode; an insulator which holds the center electrode therein in a state where a tip end portion of the center electrode protrudes therefrom; a metal shell which holds the insulator therein; a ground electrode which is fixed to the metal shell, the ground electrode having an inner side face having a width that is smaller as it advances toward a tip end side, in a portion of the inner side face positioned between a pair of tapered faces; and a discharge portion which is bonded to the inner side face of the ground electrode by laser welding so as to attain a diameter of 0.8 mm or less and a height of 0.5 mm or more, and a discharge gap being formed between the discharge portion and the tip end portion of said center electrode.

Abstract: A spark plug (10) includes a plug body (51), a center electrode (52), a ground electrode (53) and injection control side poles (61, 62, 63). The ground electrode has an end portion (53a) opposing the end of the center electrode in a direction indicated by arrow A parallel to the axis of the plug body. A tip (53b) of the ground electrode and a tip (60a) of the injection control side poles (61, 62, 63) are positioned in substantially the same plane (71) perpendicular to the axis (C). The ground electrode (53) and the injection control side poles (61, 62, 63) are arranged at substantially regular intervals around the center electrode (52).

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: A plasma-jet spark plug comprising an insulator and a ground electrode which are disposed apart from each other in an axial direction (O) to prevent a damage of the insulator. The spark plug is capable of reducing an energy loss of the ejected plasma by defining a dimension of a clearance between the insulator and the ground electrode whereby deterioration of the ignitability of the plasma-jet spark plug is prevented.

Abstract: A processing solution for forming a hexavalent chromium free, corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers comprises: trivalent chromium and oxalic acid in a molar ratio ranging from 0.5/1 to 1.5/1, wherein the trivalent chromium is present in the form of a water-soluble complex with oxalic acid; and cobalt ions, which do not form a hardly soluble metal salt with oxalic acid and are stably present in the processing solution without causing any precipitation; wherein the solution reacts with zinc when bringing it into contact with the zinc or zinc alloy plating to form a hexavalent chromium free, corrosion resistant, trivalent chromate conversion film containing zinc, chromium, cobalt, oxalic acid and silicon on the plating.

Abstract: A semiconductor device includes a semiconductor substrate, and an electrical fuse including a first conductor including a first cutting target region, and a second conductor branched from the first conductor and connected to the first conductor and including a second cutting target region, which are formed on the semiconductor substrate, wherein a flowing-out region is formed of the first conductor flowing toward outside between the first cutting target region and the second cutting target region in a condition of cutting the electrical fuse.

Abstract: A spark plug for an internal combustion engine and related manufacturing method are disclosed having a metal shell, a porcelain insulator, a center electrode and a ground electrode. The center electrode includes a substantially columnar shaped base material body, and a substantially square shaped rod-like Ir alloy tip bonded to a leading end portion of the base material body. The leading end portion has a diameter D2 smaller than a diameter D1 of the base material body. The Ir alloy tip has a square shape with a long diagonal line supposed to form a diameter A of a circumscribed circle CA of the Ir alloy tip whose inscribed circle CB is coaxial with the circumscribed circle CA and has a diameter B, with four diameters A, B, D1 and D2 lay in the relationship expressed as D1>A>D2>B.

Abstract: A spark plug comprises: a spark plug housing; an axial core electrode disposed in a longitudinal direction in the spark plug housing; and a ground electrode having a terminal part spaced apart along the longitudinal direction from a distal end of the axial core electrode and disposed in a perpendicular relation with the axial core electrode, the terminal part having a circular through hole formed along an axis coaxial with the axial core electrode, the circular through hole having a tapered inner surface and including a plurality of spiral protrusions disposed on the tapered inner surface to induce a turbulent air flow in the combustion inflow.

Abstract: A spark plug for an internal combustion engine is disclosed having a metal shell having an outer periphery formed with a mounting thread, a porcelain insulator fixedly secured to the metal shell on a central axis thereof, a center electrode retained within the porcelain insulator along a central axis thereof with a distal end located outside the porcelain insulator, and a ground electrode joined to the metal shell and having an end associated with the distal end of the center electrode to define therebetween a spark discharge gap. The ground electrode includes a facing surface intersecting the central axis of the center electrode and having a width equal to or less than 1.6 mm.

Abstract: A spark plug having a center electrode and a ground electrode wherein the spark portion of at least one of the center electrode and ground electrode includes a base material and a protective material that substantially prevents corrosion of the base material.

Abstract: A spark plug including: a center electrode (20); an insulator (10) having an axial hole (12) extending in an axial direction of the center electrode (20) and holding the center electrode (20) in the axial hole (12); a cylindrical metal shell (50) surrounding the insulator (10) and holding the insulator (10); and a ground electrode (30) having first and second end portions, an end face (35) of one end portion (32) being joined to a tip face (57) of the metal shell (50) and which is bent so that the other end portion (31) is opposed to the center electrode (20). An axial line (P) of the metal shell (50) and an axial line (O) of the insulator (10) deviate from one another so that a relationship A>B is satisfied for distances A and B as defined herein.

Abstract: A noble-metal chip (30, 90) joined to at least either a center electrode or a ground electrode, the center and ground electrodes forming a spark discharge gap, and having a circumferential edge of its facing end surface (31, 91) removed so as to form an edge-removed portion (32, 92). The edge-removal length is 0.01 mm or more and a ratio of the edge-removal length to a radius of the noble-metal chip is less than 0.3. The noble-metal chip is made of iridium or an alloy that contains iridium man amount of 70% by weight or more, and crystal grains constituting the noble-metal chip (30, 90) extends in the axial direction. Also disclosed is a method for manufacturing the spark plug.

Abstract: A spark plug according to the present invention includes a metal shell, an insulator retained in the metal shell, a center electrode secured in the insulator, and a ground electrode. The center electrode includes a base member and a thin member thinner the base member. The ground electrode includes a base member fixed to the metal shell and a protruding member that protrudes from the base member and has an end face with an inner and an outer edge. When the insulator is clean, sparks can be discharged between the thin member and the inner edge. When the insulator is fouled with carbon, sparks can be discharged between the base member and the outer edge to self-clean the insulator. Dimensional parameters and relationships are specified in the spark plug, so that the spark plug can induce spark discharges with a low discharge voltage while securing an excellent self-cleaning capability thereof.

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 (100) includes: a center electrode (2); and a ground electrode (30) which is to be exposed in a combustion chamber of an internal combustion engine and which forms a spark discharge gap with the center electrode (2), wherein at least one of the center electrode (20) and the ground electrode (30) contains an electrode material whose principal component is Ni and in which an intermetallic compound is precipitated at least intergranularly and intragranularly.

Abstract: A small-sized spark plug is provided which ensures the stability in the location of production of sparks between center and ground electrodes. The center and ground electrodes have joined thereon cylindrical members such as noble metal chips which are opposed to each other through a spark gap. The cylindrical members are so oriented to have longitudinal center lines extend parallel in misalignment with each other. This orientation results in shorter and longer intervals between end surfaces of the cylindrical members. The sparks are concentrated between portions of edges of cylindrical members located apart the shorter interval, thereby resulting in the stability in the location of production of the sparks.

Abstract: A spark plug (100) including a center electrode (130) and a ground electrode (140), which is formed by joining a ground electrode chip (143) to a ground electrode base material (141) via an intermediate member (142). A method for producing the spark plug (100) includes providing a projecting portion (142p) on the intermediate member (142), and projection-welding the intermediate member (142) to the ground electrode base material (141) by means of the projecting portion (142p), to thereby join the intermediate member 142 to the ground electrode base material (141). Further, the intermediate member (142) of the spark plug (100) includes a cylindrical columnar portion (142e) which is joined to the ground electrode chip (143), and a flange portion (142d) which is joined to the ground electrode base material (141) and which flange portion (142d) has a diameter greater than that of the cylindrical columnar portion (142e).

Abstract: A ground-electrode spark portion 32 is formed from a noble metal which contains Pt as a main component, and is joined to a main metal portion of the ground electrode 4 via an alloy layer which has a thickness ranging from 0.5 ?m to 100 ?m and in which the noble metal that constitutes the ground-electrode spark portion 32 and the metal that constitutes the main metal portion of the ground electrode 4 are alloyed with each other. The ground-electrode spark portion 32 is configured such that a distal end surface 32t facing a spark discharge gap g is smaller in diameter than a bottom surface 32u joined to the ground electrode 4; and the distal end surface 32t is protrusively located beyond the side surface 4s of the ground electrode 4.

Abstract: Spark plug has a central electrode, an insulator provided exterior to the central electrode, main metallic shell provided exterior to the insulator in such a way that the central electrode protrudes from one end, and a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode 3, with a chip being secured to either the central electrode or the ground electrode or both to form spark discharge gap g. The chip is made of a metal based on Ir which contains Rh in an amount ranging from 3 to 50 wt (50 wt % being not inclusive).