Abstract: A spark plug includes a body of revolution defining a longitudinal axis. The body has a forward axial portion with external threads, and an intermediate axial collar portion defining an axially downwardly facing sealing surface. A first electrode and a second electrode extend from the forward axial portion and define a spark gap therebetween. A hex drive portion is disposed axially above the intermediate collar portion. A gasket crush limiter includes a wall that extends axially downwardly from the intermediate axial collar portion, defining an annular pocket formed by the wall and the forward axial portion.

Abstract: Herein disclosed is universal housing for a hot surface igniter that can be removed and/or easily installed by the consumer without the need for numerous tools or assistance from experienced maintenance personnel. The igniter housing is universal and is functional for use with substantially any apparatus or device which requires a hot surface igniter. The universal housing is of simple construction formed from only two components. Various embodiments are disclosed for construction of the two components and also various attachment means are described.

Abstract: A spark plug device that includes a spark plug and a sealing ring, and a method for producing the same. The spark plug may include a body, an insulator, a center electrode, and a ground electrode. The sealing ring is secured to the body in a captive fashion. A fastening section of the body has an outer diameter that is greater than an inner diameter of the sealing ring, which has been reshaped from a flat sealing ring blank into a conical sealing ring.

Abstract: A spark plug, including an insulator, a casing including a sealing surface, and a gasket which rests against the sealing surface, the sealing surface including a plurality of recesses.

Abstract: An extruded insulator for a spark plug that is made in a manner that minimizes pores, relics and/or other defects in the insulator microstructure so that the overall dielectric strength or performance of the insulator is improved. The extruded insulator avoids many of the drawbacks associated with such defects, but also has a stepped internal bore for receiving a center electrode. In one embodiment, the extruded insulator is made with a method that uses a multi-phase extrusion process to extrude a ceramic paste around an elongated arbor and form an extruded section, and then removes the arbor from the extruded section to reveal a stepped internal bore.

Abstract: A spark plug includes a tubular metal shell that includes a metal-shell step portion extending in an inner circumferential direction, an insulator that is inserted in the metal shell, that includes a facing portion that faces the metal-shell step portion with an annular packing interposed therebetween, a center electrode that extends in the axial direction, that has a flange portion extending in an outer circumferential direction, and a seal body seals the insulator and the center electrode. In a section that contains the axial line and that is along the axial line, a distance L along the axial line from a rear end of the facing portion of the insulator to a rear end of a portion at which the flange portion is in contact with the insulator satisfies L?1.1 (mm).

Abstract: A method for producing a spark plug, including an inspection step for an insulator includes: (a) a step of preparing an assembly; (b) a step of attaching the assembly to a pressure vessel; (c) a step of attaching an insulating member to the assembly so as to cover at least a part of a surface of a portion of the insulator that is exposed at the rear side; and (d) a step of pressurizing an interior of the pressure vessel and applying a predetermined voltage between the metal terminal and the metal shell. The producing method further includes a step of adhering a lubricant to at least one of a surface of the insulator and an inner surface of the insulating member.

Abstract: A spark plug includes a main fitting having a first, second, and third portions adjacent to each other. The spark plug further includes an insulator having a first opposing portion with a predetermined portion opposed to the first portion with a first interval, a second opposing portion with a second portion opposing the second portion with a second interval, and a third opposed portion opposed to the third portion. A connecting portion between the second opposing portion is supported by a support portion, and a value obtained by dividing the first interval by a length from the support portion to a rear end portion of the predetermined portion is configured to be smaller than a value obtained by dividing the second interval by a length from the support portion to a rear end portion of the second opposed portion.

Abstract: A corona ignition assembly comprising a plurality of different insulators disposed between an ignition coil assembly and firing end assembly is provided. A high voltage center electrode extends longitudinally between an igniter central electrode and the ignition coil assembly. A high voltage insulator formed of a fluoropolymer surrounds the high voltage center electrode, and a firing end insulator formed of alumina surrounds the igniter central electrode. According to one embodiment, a glue formed of a compliant and insulating material, such as a silicon-based material, forms a seal between the high voltage insulator and the firing end insulator. According to another embodiment, a dielectric compliant insulator is disposed between the high voltage insulator and the ignition coil assembly, and the glue forms a seal therebetween. The glue fills air gaps to prevent unwanted corona discharge, and thus extends the life of the materials and directs energy to the firing end.

Abstract: A spark plug includes an insulator, a center electrode, a metallic shell, and a ground electrode. The insulator contains not less than 90.0 mass % and not greater than 98.1 mass % of Al2O3 with respect to a total mass of elements, as reduced to oxides, contained in the insulator, and has a porosity not greater than 5%. Assuming that a porosity of the insulator after a heat treatment is B, a difference (B?A) of the porosities before and after the heat treatment is not greater than 3.5%. In the heat treatment, the insulator is placed in a furnace, and a temperature in the furnace is increased from a room temperature to 1400° C. at a temperature increase rate of 7° C./min and is held at 1400° C. for 30 minutes, and thereafter, the temperature is decreased from 1400° C. to 400° C. at a temperature decrease rate of 10° C. or less per 5 minutes and is decreased to the room temperature.

Abstract: An electrically conductive glass seal for providing a hermetic bond between an electrically conductive component and an insulator of a corona igniter is provided. The glass seal is formed by mixing glass frits, binder, expansion agent, and electrically conductive metal particles. The glass frits can include silica (SiO2), boron oxide (B2O3), aluminum oxide (Al2O3), bismuth oxide (Bi2O3), and zinc oxide (ZnO); the binder can include sodium bentonite or magnesium aluminum silicate, polyethylene glycol (PEG), and dextrin; the expansion agent can include lithium carbonate; and the electrically conductive particles can include copper. The finished glass seal includes the glass in a total amount of 50.0 to 85.0 weight (wt. %), and electrically conductive metal particles in an amount of 15.0 to 50.0 wt. %, based on the total weight of the glass seal.

Abstract: In an internal combustion engine ignition coil apparatus, a high-voltage supplying portion has: a protector that is bonded to an ignition coil main body, an electrical conductor, and a resistor that is connected in series between the ignition coil main body and the electrical conductor, and that reduces conductive noise. An electromagnetic wave absorber that shields radiated noise that is generated in the high-voltage supplying portion is mounted to an engine block so as to surround the protector and the resistor. An end surface of the resistor near the ignition coil main body is disposed so as to be aligned with an end surface of the electromagnetic wave absorber near the ignition coil main body.

Abstract: A spark plug having an insulator formed of an alumina-based sintered material which contains an Si component and a rare earth element component that satisfy the following conditions (1) and (2): (1) an oxide-reduced amount of the Si component (mass %) is greater than or equal to 0.05 and less than or equal to 0.45; and (2) a ratio of an oxide-reduced amount of the rare earth element component to an oxide-reduced amount of the Si component is greater than or equal to 2.5 and less than or equal to 4.5, and which has alumina grains and an alumina grain boundary phase including a complex oxide crystal phase satisfying the following condition (3): (3) the complex oxide crystal phase contains at least two components selected from among an Al component, an Si component, a Group 2 element component, and a rare earth element component.

Abstract: A spark plug includes: a metal shell including a tool engagement portion and having a through hole; an insulator disposed in the through hole of the metal shell; and a metal terminal including: a trunk portion disposed in an axial hole of the insulator; a flange portion having a larger diameter than the trunk portion; and a head portion having a smaller diameter than the flange portion. A minimum thickness of an exposed portion of the insulator is equal to or less than 2.5 mm. A diameter difference between the maximum outer diameter of the head portion and the maximum outer diameter of the tool engagement portion is equal to or less than 9 mm, or a diameter difference between the maximum outer diameter of the exposed portion and the maximum outer diameter of the head portion is equal to or less than 2.3 mm.

Abstract: A method for producing a spark plug for internal combustion engines, having a metallic shell, a ceramic insulator held in the shell, a center electrode embedded in the insulator, and a ground electrode implemented as a bridge attached to the front end of the shell, wherein an end piece made of a precious metal is attached to the front end of the center electrode and a counterpart is attached to the bridge opposite the end piece, between which is formed a spark gap. A cylindrical body made fully or partially of the precious metal or precious metal alloy intended for the end piece and that is longer than the end piece is welded onto the front end of the center electrode. A bridge is used that has, in the center, a hole, the cross-section of which is matched to the cross-section of the cylindrical body. The bridge is placed on the front end of the shell in such a manner that the forward-facing end of the cylindrical body enters the hole in the bridge.

Abstract: A spark plug includes an insulator having an axial hole, a metal terminal member having an insert portion and a depression formation zone existing on the insert portion and having depressions, and a metallic shell. The spark plug satisfies the following conditions: (1) the insert portion has a length H of 35 mm or more; (2) the depression formation zone has a length F of 13 mm or more; (3) the insert portion has a smooth surface zone on its outer circumferential surface; (4) the ratio (A/B) between diameter A of a forward end of the insert portion and inside diameter B of the insulator measured at the forward end satisfies the relational expression 0.9?A/B?0.98; and (5) Vickers hardness of the insert portion measured at the center of a cross section of the insert portion is 150 Hv or more to 350 Hv or less.

Abstract: A spark plug (20) for being threaded into a cylinder head (28) includes a shell (24) with threads (26) disposed at a predetermined angled relative to the ground electrode (34). The position of the threads (26) relative to the ground electrode (34) places the ground electrode (34) in a predetermined position in the combustion chamber (22) and relative to components of the engine, thus allowing the ground electrode (34) to provide a robust and reliable ignition. The threads (26) are formed by a thread forming apparatus (102) that includes an orientation tool (38) to position the ground electrode (34) relative to a thread forming apparatus (102), allowing the thread forming apparatus (102) to form the threads (26) at the desired angle (?).

Abstract: A spark plug includes an insulator having an axial hole, a metal terminal member having an insert portion and a depression formation zone existing on the insert portion and having depressions, and a metallic shell. The spark plug satisfies the following conditions: (1) the insert portion has a length H of 35 mm or more; (2) the depression formation zone has a length F of 13 mm or more; (3) the insert portion has a smooth surface zone on its outer circumferential surface; (4) the ratio (A/B) between diameter A of a forward end of the insert portion and inside diameter B of the insulator measured at the forward end satisfies the relational expression 0.9?A/B?0.98; and (5) Vickers hardness of the insert portion measured at the center of a cross section of the insert portion is 150 Hv or more to 350 Hv or less.

Abstract: A spark plug for an internal combustion engine capable of ensuring sufficient gastightness of a combustion chamber and meeting demand for a reduction in diameter.

Abstract: A composite ignition device includes a positive electrode having a tip formed thereon that is bonded to a first insulator to form a firing cone assembly. A second insulator having a negative capacitive element embedded therein is attached to the firing cone assembly. A positive capacitive element is disposed in the second insulator and is separated from the negative capacitive element by the second insulator. The positive capacitive element is coupled to the positive electrode. The positive and negative capacitive elements form a capacitor. A resistor is coupled to the positive capacitive element. An electrical connector is coupled to the resistor and attached to the second insulator. A shell including a negative electrode having a tip is attached to the second insulator and the firing core assembly and coupled to the negative capacitive element. The negative electrode tip is spaced apart from the positive electrode tip.

Abstract: A spark plug includes an insulator extending along an axis and a metal shell provided on the outer periphery of the insulator. The metal shell includes a thread portion for threadedly engaging with a mounting hole of an internal combustion engine and a seat portion having a tapered surface whose outer diameter decreases gradually toward a leading end side. The tapered surface contacts with a bearing surface of the internal combustion engine when the thread portion is engaged with the mounting hole. Annular protruding portions or a helical protruding portion are formed within a range on the tapered surface from an outermost peripheral portion to a part forming an outer diameter occupying 95% of the diameter of the outermost peripheral portion. The arithmetic mean roughness of a surface of the tapered surface within the range is set to 1-5 ?m on a section including the axis.

Abstract: A spark plug includes a tubular insulator and a tubular metal shell secured to an outer peripheral surface of the insulator by crimping. The tubular metal shell includes: an inner peripheral surface where powder for sealing is filled between the outer peripheral surface and the inner peripheral surface; a tool engagement portion overhanging in a polygonal shape; and a crimped lid disposed at an end portion of the metal shell coupled to the tool engagement portion, the end portion being bent toward the outer peripheral surface of the insulator by crimping. A relationship between a length L and a thickness t satisfies 2.50?L/t?3.10, the length L being a length along a shape of the crimped lid from the tool engagement portion to the insulator in a planar surface that passes through the axis, the thickness t being a thickness at an intermediate portion of the crimped lid.

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: 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: 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: A spark plug having excellent load life performance even when the spark plug receives an impact or vibration. The spark plug includes an accommodated portion of a metallic terminal, which is accommodated in an axial hole of an insulator, having a plurality of bent portions formed as a result of proper bending of the accommodated portion. The bent portions are in close vicinity to an inner circumferential surface of the insulator at three or more locations, and are present without localizing in the radial direction of the axial hole.

Abstract: A spark plug comprises an insulator and a metal shell. The insulator includes a nose length portion at the forward end, and a tapered portion, extending from the rear end of the nose length portion toward the rear end of the insulator, increased in diameter toward the rear end. The metal shell includes a shoulder portion, protruding inward and having a retaining surface by which the tapered portion is retained, and a male thread portion on the outer peripheral side of the shoulder portion, and the thread diameter of the male thread portion is set to M12 or less. When the insulator's cross-sectional area, perpendicular to an axis, passing through the boundary between the nose length section and tapered portion is B (mm2), and the metal shell's cross-sectional area, perpendicular to the axis, passing through the tip of the retaining surface is C (mm2), 2.80?C/B?3.50 is satisfied.

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: 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 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 spark plug (20) includes a center electrode (24) and a ground electrode (22). The electrodes (22, 24) include a core (26) formed of a copper (Cu) alloy and a clad (28) formed of a nickel (Ni) alloy enrobing the core (26). The Cu alloy includes Cu in an amount of at least 98.5 weight percent, and at least one of Zr and Cr in an amount of at least 0.05 weight percent. The Cu alloy includes a matrix of the Cu and precipitates of the Zr and Cu dispersed in the Cu matrix. The Ni alloy of the clad (28) includes Ni in an amount of at least 90.0 weight percent. The Ni alloy also includes at least one of a Group 3 element, a Group 4 element, a Group 13 element, chromium (Cr), silicon (Si), and manganese (Mn) in a total amount sufficient to affect the strength of the Ni alloy.

Abstract: A plasma jet spark plug having increased capacitive discharge current, and thus improved plasma generation efficiency. The plasma jet spark plug includes an insulating body having an axial hole, a center electrode, a metal shell, and a cavity portion formed by the inner peripheral surface of the insulating body and the leading end face of the center electrode. A conductive layer formed from a conductive material is provided on at least one portion of at least one of: (a) a surface on the insulating body outer peripheral surface opposed to the inner peripheral surface of the metal shell, the conductive layer electrically connected to a ground electrode; and (b) a surface on the insulating body inner peripheral surface opposed to the outer peripheral surface of the center electrode, the conductive layer electrically connected to the center electrode.

Abstract: The present invention provides a technique of suppressing the generation of radio noise in a spark plug, wherein a high dielectric constant fixation-assisting member, formed of a high dielectric constant material which is higher in dielectric constant than alumina, is provided between a metallic shell and a second conductive portion CP2 which includes a metallic terminal of the spark plug 100.

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

Abstract: 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 sealing member for a cylindrical spark plug having a metal shell with threaded ridges thereon to be screwed into a mounting hole of a combustion engine, the sealing member comprised of a piece of annular sheet material made of austenitic stainless steel or ferritic stainless steel that is folded back in a radial direction so as to form a region where at least two or more layers of the sheet material are overlapped in an axial direction.

Abstract: A spark plug designed for fitting in tight spaces of an engine compartment is disclosed. The spark plug has a conductive terminal attached to one end of a flexible central electrode and has a ceramic insulator partially encasing the flexible central electrode. The part of the flexible central electrode between the ceramic insulator and the conductive terminal is encased in a flexible insulator. The flexible part of the central electrode may be bent away from the axis of the ceramic insulator accommodating both installation and servicing of the spark plug in tight spaces.

Abstract: A spark plug for an internal combustion engine capable of ensuring sufficient gastightness of a combustion chamber and meeting demand for a reduction in diameter.

Abstract: The invention relates to a spark plug for igniting a combustible gas mixture in an internal combustion engine, comprising an ignition electrode (4), an electrical supply line (5), to which the ignition electrode (4) is connected, an insulator body (6), through which the supply line (5) is passed, a housing head (2), which rests in sealing fashion on the insulator body (6) and bears an outer thread (3) for the purpose of screwing it into an internal combustion engine, a tube housing (9), which is fixed on the housing head (2), surrounds the insulator body (6) and has a hexagon head (13). The invention provides that the tube housing (9) surrounds an insulator body holder (7), which is welded to the housing head (2) and presses the insulator body (6) with a prestress against the housing head (2).

Abstract: A spark-ignited, internal combustion engine ignition device to increase electrical transfer efficiency of the ignition by peaking the electrical power of the spark during the streamer phase of spark creation and improving combustion quality, incorporating an electrode design and materials to reduce electrode erosion due to high power discharge, an insulator provided with capacitive plates to peak the electrical current of the spark discharge, and concomitant methods.

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: A spark plug for a model engine includes a main body. The main body has a through hole at a central portion thereof and an engaging portion disposed at a first end of the through hole to position a central electrode. The central electrode includes a connection portion at one end thereof and an extension portion at an opposing end thereof. The connection portion is protruded from the first end of the through hole. The extension portion is axially disposed in the through hole and connected with an ignition coil. One part of the through hole of the main body, close to the extension portion, is gradually enlarged towards a second end of the through hole to form an enlarged opening. The gas in the enlarged opening can be burned in an enlarged way and diffused in the cylinder of the model engine entirely, providing a complete combustion effect to enhance the horsepower of the model engine and stabilize the idle speed.

Abstract: A spark plug for an internal combustion engine includes a ground electrode, a center electrode, an insulator, a housing, and a folded packing which is situated on an outer circumference of the housing. The folded packing has: a hollow profile in cross section; a free leg directed outwards; and a support region. The folded packing lies on a contact surface in a support region, and the free leg is situated at an angle to the support region. The folded packing is pressed together during the mounting of the spark plug, and the free leg of the folded packing is designed to bend over in the direction of the support surface during the mounting to provide a diameter enlargement of the folded packing.

Abstract: A spark plug assembly (10) for engine applications where the combustion chamber is difficult to access when servicing or replacing a spark plug. The spark plug assembly (10) includes a fairly traditional spark plug component (28) to which an elongated tubular conduit (12) is attached, such as by welding, to a portion of the metallic shell (32). The conduit (12) contains an upper ceramic insulator (52) adjacent its top end (14) disposed in end-to-end abutting contact with an outer elastomeric insulator (58). The ceramic insulator of the spark plug component (28), herein referred to as a lower ceramic insulator (30), is surrounded by the outer elastomeric insulator (58) and held securely within the conduit (12) thereby. An inner elastomeric insulator (62) is disposed in a continuous passageway formed between aligned central bores formed in the respective upper ceramic (52) and outer elastomeric (58) insulators.

Abstract: A spark plug and method of manufacturing the same, the spark plug including a metal housing holding an insulator therein, the metal housing having a threaded portion formed on an outer circumferential surface of a frontward portion of the metal housing in a crimp portion formed at a rear end of the metal housing and crimping the insulator in the axial hole of the metal housing. Furthermore, the rear-end portion of the threaded portion has a hardness that is higher than that of the crimp portion.

Abstract: A sealing member for a cylindrical spark plug having a metal shell with threaded ridges thereon to be screwed into a mounting hole of a combustion engine, the sealing member comprised of a piece of annular sheet material made of austenitic stainless steel or ferritic stainless steel that is folded back in a radial direction so as to form a region where at least two or more layers of the sheet material are overlapped in an axial direction

Abstract: A spark plug insulator having high dielectric strength, high density, and an optical property that allows the passage of light.

Abstract: A spark plug and method of manufacturing the same, the spark plug including a metal housing holding an insulator therein, the metal housing having a threaded portion formed on an outer circumferential surface of a frontward portion of the metal housing in a crimp portion formed at a rear end of the metal housing and crimping the insulator in the axial hole of the metal housing. Furthermore, the rear-end portion of the threaded portion has a hardness that is higher than that of the crimp portion.

Abstract: A spark plug includes a metallic housing, an insulator fixed in the metallic housing, a center electrode fixed in the insulator, a ground electrode opposed to the center electrode via a spark discharge gap, and a protective coat formed on the surfaces of a metallic housing and a gasket. The protective coat includes a galvanized film formed on the surfaces of the metallic housing and the gasket and a chromate film successively laminated on the galvanized film. The chromate film is hexavalent chromium-free and contains trivalent chromium as a major component. The chromate film has a film thickness not smaller than 0.05 ?m and not greater than 0.18 ?m, and the chromate film contains a metallic component which is robust against oxidation compared with zinc. Furthermore, the chromate film has a film hardness equal to or less than 1 GPa in the temperature range from a room temperature to 180° C.

Abstract: A method of making an ignition device and center wire assembly that includes first, second and third electrode members, a conductive seal, and a noise suppressing seal. The method locates the first electrode member at an axial end of the center wire assembly near a spark gap and the third electrode member at an axial end of the center wire assembly such that it receives an electrical ignition pulse and a second electrode member between the first and third electrode members. Furthermore, the method locates the conductive seal between the first and second electrode members and the noise suppressing seal between the second and third electrode members.