Abstract: A spark plug for an internal combustion engine includes insulating glass having a tubular shape, a central electrode including a tip protruding portion, a housing having a tubular shape, and a plug cover provided over an auxiliary combustion chamber. The plug cover is provided with injection holes through which the auxiliary combustion chamber communicates with the exterior. The central electrode includes a base material and a core material disposed inside the base material and having a higher thermal conductivity than the base material. The core material includes a large diameter portion and a small diameter portion continuously formed on a tip side of the large diameter portion. The small diameter portion has a smaller diameter than the large diameter portion, and includes, in a part of the small diameter portion in an axial direction, a small-diameter columnar portion having a constant diameter.

Abstract: Methods and systems are provided for operating a cylinder with a series gap igniter coupled to an ion sensing module. In one example, a method may include determining a location of an initial combustion in a cylinder from a series gap igniter based on a pressure rise rate in the cylinder, the ignition spark initiating combustion in the cylinder; and adjusting at least one setting of the cylinder based on the determined location. In this way, combustion stability and efficiency may be increased without increasing a cost and complexity of the engine.

Abstract: A plug connector capable of increasing the sealing between a rubber member and an outer circumferential surface of a spark plug insulator for improvement in current leakage resistance. The plug connector includes a conductive part that electrically connects a spark plug and a power supply member for power supply to the spark plug; and a rubber member that covers the conductive part. The spark plug has an insulator and a terminal electrode protruding toward the rear from a rear end of the insulator. The plug connector further includes a ring member arranged on an outer circumference of the rubber member.

Abstract: A coating for spark plugs and engine parts is resistant to fouling. The coating may be applied to the spark plug or engine part by dipping the part in a sol gel solution, ensuring it wets the part, and extracting it at a slow, controlled rate. As the part is allowed to dry, the sol gel reacts with moisture in the air to form a thin oxide film. Unlike conventional sol gel applications, which apply the oxide directly to the part, the present invention may form an oxide coating, in situ, while drying in place on the part.

Abstract: A spark plug with an insulator that includes: a first portion having a first inner diameter with a front end of a trunk portion of a metal terminal disposed therein; a second portion having a second inner diameter larger than the first inner diameter, and including a portion 1 mm or more forward of a rear end of the insulator; and a third portion disposed between the first portion and the second portion and having a third inner diameter larger than the first inner diameter and smaller than the second inner diameter. The trunk portion of the metal terminal includes: a front trunk portion and a rear trunk portion with a front end of the rear trunk portion positioned forward of a rear end of the third portion of the insulator, the rear trunk portion having an outer diameter larger than the outer diameter of the front trunk portion.

Abstract: A corona igniter (20) comprises a central electrode (22) surrounded by an insulator (26), which is surrounded by a conductive component. The conductive component includes a shell (34) and an intermediate part (36) both formed of an electrically conductive material. The intermediate part (36) is typically attached to a lower ledge (52) of the insulator outer surface (50) prior to inserting the insulator (26) into the shell (34). The shell firing end (56) is typically aligned with the lower edge and the intermediate firing end. The conductive inner diameter (Dg) is less than an insulator outer diameter (Dio) directly below the lower ledge (52) such the insulator thickness (ti) increases toward the electrode firing end (40).

Abstract: An electrode assembly for electro-hydraulic forming tool in which the insulation sleeve is assembled over an electrode rod. The insulation sleeve has a deflection surface that is beveled or oriented at an angle relative to the axis of the electrode rod. The electrode assembly may include a replaceable conical receptacle that facilitates placement of an electrode tip an insulation sleeve tip. An electrode tip profile that is shaped to minimize erosion caused by discharge of the electro-hydraulic forming machine.

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: An ignition plug, wherein, when a relative density of a portion of an insulator, which is positioned between a radial virtual plane including a front end of the insulator and a radial virtual plane including a front end of a portion of the insulator which is in contact with a metal shell or the plate packing, is referred to as A (%), and a relative density of a portion of the insulator, which is positioned between the radial virtual plane including the front end of the portion of the insulator which is in contact with the metal shell or the plate packing and a radial virtual plane including a center of a resistor in an axial direction, is referred to as B (%), the following equations are satisfied: 93.90?A, and 0.10?A?B?0.90.

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: An igniter for igniting a fuel/air mixture using a corona discharge, generated by a high-frequency electric high voltage, in an internal combustion engine having one or more combustion chambers delimited by walls at ground potential, comprising an ignition electrode, which traverses in an electrically insulated manner one of the walls delimiting the particular combustion chamber and constitutes in cooperation with the walls of the combustion chamber, that are at ground potential, an electrical capacitance. Comprising a metallic or metallized outer member and an elongate passage extending through the outer member, through which extends the ignition electrode, and comprising an insulator which encloses the ignition electrode and insulates it electrically from the outer member, wherein the ignition electrode, the insulator, and the passage have a common longitudinal direction.

Abstract: A corona igniter 20 includes an insulator 28 surrounding a central electrode 24 and a shell 30 surrounding the insulator 28. The shell 30 presents a shell gap 38 having a shell gap width ws between a shell lower end 34 and a shell inner surface 90 or shell outer surface 92. The shell 30 has a shell thickness ts decreasing toward the shell lower end 34 allowing the shell gap width ws to increase toward the shell lower end 34. The shell gap 38 is open at the shell lower end 34 allowing air to flow therein, and the shell gap width ws is greatest at the shell lower end 34. The increasing shell gap width ws enhances corona discharge 22 along the insulator 28 between the central electrode 24 and shell 30.

Abstract: A corona igniter 20 includes an electrode gap 28 between the central electrode 22 and the insulator 32 and a shell gap 30 between the insulator 32 and the shell 36. An electrically conductive coating 40 is disposed on the insulator 32 along the gaps 28, 30 to prevent corona discharge 24 in the gaps 28, 30 and to concentrate the energy at a firing tip 58 of the central electrode 22. The electrically conductive coating 40 is disposed on an insulator inner surface 64 and is spaced radially from the electrode 22. The electrically conductive coating 40 is also disposed on the insulator outer surface 72 and is spaced radially from the shell 36. During operation of the igniter 20, the electrically conductive coating 40 provides a reduced voltage drop across the gaps 28, 30 and a reduced electric field spike at the gaps 28, 30.

Abstract: A task of this invention is to provide a spark plug that is superior in withstand voltage characteristics at high temperatures. A spark plug of this invention is equipped with a center electrode, an insulator, and a metal shell, and is characterized by that the insulator is equipped with an alumina-based sintered body containing silicon component (Si component), magnesium component (Mg component), at least one component of calcium component, strontium component, and barium component, and a rare earth element component (RE component), that a grain boundary phase of the alumina-based sintered body has a hexaaluminate crystal containing the RE component, that, in the alumina-based sintered body, the weight ratio of the RE component to the Mg component is 5.4?RE oxide/MgO?17.5, and that the content of an alkali metal component in terms of oxide in a spot having a diameter of 0.

Abstract: A vehicle ignition system is provided that alleviates the problems associated with excessive voltage demand by spark plugs. The ignition system has a spark plug with an electrode and a voltage relief feature operatively connected with the electrode. The voltage relief feature is operable to discharge current from the electrode at a predetermined voltage.

Abstract: A spark plug having an insulator with improved breakage resistance. The spark plug has a cross-section that satisfies the following relationship: 0.6 mm<=L, where “A” represents a connection point between a support portion of the insulator and an insulator trunk portion formed at a front end side with respect to the support portion, where “B” represents a position closer to the outer circumference side among the positions of (a) an innermost position of a contact portion where the support portion and a packing are in contact with each other and (b) an intersection of the support portion and a virtual straight line that is parallel to an axial line of the spark plug and extends from an innermost circumferential end of a stepped portion of a metal shell, and where “L” represents a length of a path from point “A” to point “B” along a surface of the insulator.

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

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

Abstract: Provided is a spark plug which allows a predetermined resistance to be imparted to a resistor with restraint of variation in resistance of the resistor and in turn, enables enhancement of yield. The spark plug includes a ceramic insulator having an axial hole extending in the direction of an axis CL1, a center electrode, and a terminal electrode. A resistor is provided in the axial hole through sintering of a resistor composition which contains a conductive material such as carbon black, glass powder, and ceramic particles other than glass. As viewed on a section of the resistor taken along a direction orthogonal to the axis CL1, 50% or more of sintered glass powder formed through sintering of the glass powder has a circularity of 0.8 or greater.

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

Abstract: A spark plug (20) includes a center electrode (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 spark plug exhibits a satisfactory withstand voltage characteristic and sufficient mechanical strength in a high temperature environment exceeding 700° C. The spark plug has a center electrode, an insulator, and a ground electrode, characterized in that the insulator is formed of an alumina-based sintered material containing an Si component, a Group 2 element (2A) component, and a rare earth element (RE) component; that the alumina-based sintered material has an RE-?-alumina crystal phase; and that the mean crystal grain size DA(RE) of the RE-?-alumina crystal phase and that of alumina DA(Al) satisfy the following relationship (1): 0.2?DA(RE)/DA(Al)?3.0.

Abstract: The invention relates to an ignition device for igniting fuel in an internal combustion engine by means of a corona discharge, comprising an ignition electrode, an outer conductor which surrounds the ignition electrode and has a forward end and a rear end, and an electrical insulator which is arranged between the ignition electrode and the outer conductor, wherein the insulator and the ignition electrode project beyond the forward end of the outer conductor in longitudinal direction and the ignition electrode comprises a plurality of electrode branches which each start from a base point, wherein the insulator extends beyond the base points in longitudinal direction. According to the invention an end surface of the electrode branches is uncovered.

Abstract: A spark plug having sufficient durability for an internal combustion engine can restrain a sharp increase in resistance of a resistor in spite of its reduced size. The spark plug comprises an insulator having an axial hole, a metallic shell provided on the outer circumference of the insulator, a center electrode inserted into a front end portion of the axial hole, a terminal electrode inserted into a rear end portion of the axial hole, and a ground electrode. A circular columnar resistor is disposed within the axial hole between the center electrode and the terminal electrode, thereby electrically connecting the center electrode and the terminal electrode. The resistor is composed of carbon black that serves as a conductive material, a glass powder, and ceramic particles. Each of the ceramic particles has a maximum particle size of 0.5 ?m or less.

Abstract: An extension-type spark plug includes an upper terminal stud and a lower terminal stud axially spaced from one another in electrical communication with one another. An upper tubular insulator having a through cavity surrounds at least a portion of the upper terminal stud. A lower insulator constructed of a separate piece of material from the upper insulator has a through cavity surrounding at least a portion of the lower terminal stud. A spring member is disposed between the upper terminal stud and the lower terminal stud and biases the upper terminal stud and the lower member away from one another. The spring member allows the upper terminal stud to move axially under an externally applied force sufficient to overcome the bias imparted by the spring member and maintains electrical communication between said upper terminal stud and said lower terminal stud.

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 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 having a glass seal formed from a first glass material and a second glass material. The first glass material has a glass transition temperature/softening point that is greater than the glass transition temperature/softening point of the second glass material. The first glass material and second glass material form a matrix and when combined with a filler have thermal expansion rates and properties the approximate leaded glass.

Abstract: An essentially-elongated spark plug for an internal combustion engine of a motor vehicle, including: an essentially-capacitive lower part including two coaxial electrodes; an essentially-inductive upper part including a central mandrel, a coaxial winding around the mandrel, and an external tubular casing that serves as electromagnetic armor; and an insulant disposed radially between the casing and the winding. The essentially-inductive upper part includes a second internal casing of electromagnetic armor, which is disposed radially between the insulant and the external casing.

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 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 spark plug for an internal combustion engine of a motor vehicle; the spark plug is embodied with a generally essentially long shape and includes: an essentially capacitive lower part including two coaxial electrodes, one of which is a central electrode, and the other a threaded shell for screwing in the spark plug on the engine; and an essentially inductive upper part including a central winding including a plurality of coils wound around a coaxial mandrel, an envelope, and an insulator inserted between the envelope and the winding. The essentially capacitive part and the essentially inductive part are mechanically interconnected as to enable transmission of a clamping couple applied to the envelope to the essentially capacitive lower part. The mandrel can be elastically deformed as to compensate effects of dilation of the insulator.

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 insulator for a spark ignition device is disclosed which includes an electrically insulating ceramic core tube having a terminal end, a firing end and an inner bore which extends along a longitudinal bore axis from the terminal end to the firing end and an electrically insulating, ceramic core nose tube having a second outer surface and a second bore where the second outer surface of said ceramic core nose tube is in nested engagement with and directly bonded to the bore of the ceramic core tube proximate the firing end. The insulator also may include a similarly nested and directly bonded shoulder tube on an outer surface of the core tube, or a nested and directly bonded mast tube on an outer surface of the core tube. The ceramics may include alumina-based ceramics, as well other suitable ceramic materials, and the tube may be made from the same ceramic compositions or different ceramic compositions.

Abstract: A spark plug for an internal combustion engine is provided which includes a metal shell, a porcelain insulator, a center electrode, a main ground electrode, and auxiliary ground electrodes. Each of the auxiliary ground electrodes has an end face facing the insulator to define an auxiliary spark gap. The end face includes an increasing-radial distance surface which is located at a distance from a longitudinal center line of the spark plug in a radial direction thereof which increases as approaching to the metal shell. The insulator nose has a wall thickness T meeting a relation of 0.3 mm?T?0.7 mm. This avoids a great local increase in electrical field strength on the auxiliary ground electrode to minimize excessive discharge within the auxiliary spark gap to enhance carbon fouling resistance and durability of the spark plug.

Abstract: A method for manufacturing a starting element, in particular a sheathed-element glow plug, for the combustion process in an internal combustion engine having a ceramic element (1, 3) is proposed, which substantially improves the glazing of the ceramic element (1, 3). According to the present invention, this is achieved by a dry glaze (2) being applied on the ceramic element (1, 3).

Abstract: A spark plug comprising an insulator, on at least a part of a surface of the insulator being formed a marking layer and a glaze layer, wherein the marking layer is exposed on the surface of the insulator and has a composition as described herein.

Abstract: A spark plug includes a ceramic component, whose surface is at least in part coated with a glaze, with the glaze containing 0.6% to 4% by weight of fluoride and 6% to 11.2% by weight of zinc oxide.

Abstract: In an ignition device for an internal combustion engine which is mounted in a cylinder head in a state where a spark plug and an ignition coil are integrated with each other, the plug side tube section is made of ceramics and internally accommodates a center electrode and the coil side tube section is made of ceramics, with one of a primary winding and a secondary winding being wound around the coil side tube section. The plug side tube section and the coil side tube section are constructed as separate bodies and then combined with each other. This shortens the overall lengths of both the tube sections, thus preventing the occurrence of cracks or bends at calcining and improving the dimension accuracy after the calcining.

Abstract: The present application is to provide a spark plug where a marking layer 2m under a glaze layer 2d can form a color stably, even if the Pb amount is decreased in the glaze layer. The glaze layer 2d is formed on an insulator 2 of the spark plug, and the marking layer 2m is formed under the glaze layer 2d. The glaze layer 2d contains, e.g., 1 to 25 mol % of a Zn component in terms of Zno and 5 mol % or lower, e.g., 1 mol % or lower of a Pb component in terms of PbO. On the other hand, the marking layer 2m is adjusted in kinds and amounts of metallic element components in such manners that a tint seen through the glaze layer 2d is 3 or lower in brightness specified by JIS:Z8721 as well as 3 or lower in chroma specified by JIS:Z8721, or 4 or lower in the brightness specified by JIS:Z8721 as well as 2 or lower in the chroma specified by JIS:Z8721.

Abstract: The seal between the insulator and the center electrode is to be improved in a spark plug for an internal combustion engine comprising a shell (12), an insulator (16) located in the shell and composed of a sintered ceramic material, as well as a center electrode (18) and a terminal stud (22) that have an electrically conductive connection with each other and are located in the insulator. For this purpose, it is provided that a cermet (28) abuts the center electrode, the ceramic phase of which is composed of the same or a similar material as the insulator, and the metallic phase of which is composed of a material having good electrical conductivity. Since the material properties of the cermet are similar to those of the insulator—the thermal expansion, in particular, is same—a particularly good seal is created between the cermet and insulating body.

Abstract: A ceramic sheathed-element glow plug is proposed in which a metallic tubular holder holds a ceramic U-shaped heating device in a cantilevered fashion at its combustion chamber side end and has a terminal stud for applying a voltage to the ceramic heating device on the end remote from the combustion chamber. At its end enclosed by the holder, the ceramic heating device has a segment of greatest diameter and is coated with an insulating layer which has recesses for an electrical contacting. One recess is provided at the end of the ceramic heating device remote from the combustion chamber and a second recess is provided on the external wall of the ceramic heating device. A for an electrically conductive sealing compound is provided between the external wall of the ceramic heating device and the internal wall of the holder.

Abstract: In a spark plug, whose shell is provided with an eccentrically positioned, full-length, longitudinal bore designed to hold an insulating element, parts of the shell having varying wall thicknesses and a pressure measuring device being located in a part of greater wall thickness. In order to simplify connection with the ignition cable or coil, respectively, and to avoid breakage of the insulator, the spark plug insulator is configured as a multi-piece element and comprise at least an upper piece carrying the high voltage connector, a lower piece adjacent to the combustion chamber, and an insulating intermediate element of flexible material, which is placed between the upper and the lower piece of the insulator.

Abstract: An insulator for spark plug comprises an alumina-based sintered body comprising: Al2O3 as a main component; and at least one component (hereinafter referred to as “&bgr; component”) selected from the group consisting of Ca component, Sr component and Ba component, wherein the alumina-based sintered body comprises particles comprising a compound comprising the &bgr; component and Al component, the compound having a molar ratio of the Al component to the &bgr; component of 4.5 to 6.7 as calculated in terms of oxides thereof, and has a relative density of 90% or more.

Abstract: A spark plug having enhanced heat transfer capabilities is provided. The spark plug comprises a tubular insulator body, a center electrode and a thermally conductive filler material. The tubular insulator body has an inner surface, and the center electrode has an outer surface. The center electrode is positioned within the tubular insulator body such that a gap is formed between at least a portion of the inner surface of the tubular insulator body and at least a portion of the outer surface of the center electrode. The thermally conductive filler material has a high heat transfer coefficient. It is positioned within at least a portion of the gap so as to intimately contact the inner surface of the tubular insulator body and the outer surface of the center electrode. Positioned accordingly in the gap, the thermally conductive filler material enhances the ability of the spark plug to transfer heat away from the firing tip and into the body of the spark plug.

Abstract: A gasket for a threaded element such as a spark plug to be screwed into a threaded hole of a support such as a cylinder head is provided. The threaded element has a threaded portion and an annular seat portion. The gasket is installed on the threaded element and compressed between the seat portion and an outer surface of the support around a threaded hole, when the threaded element is screwed into the threaded hole, to provide a seal between the threaded portion and the threaded hole. The gasket is formed from an annular sheet metal and in the form of an annular strip of a cross section including a plurality of bent portions. The cross section is made by a plane including a center axis of the gasket and of a such a bent shape as to enable an imaginary reference line which is located on the above described plane and parallel with the center axis, to cross at least three portions of the cross section. The initial axial size of the gasket, i.e.

Abstract: A ceramic sheathed element glow plug has a tubular metal casing holding a ceramic U-shaped heating device cantilevered at its end facing the combustion chamber, and on the end remote from the combustion chamber, it has a terminal pin for applying a voltage to the ceramic heating device. In the metal casing, a ceramic bushing and a ring follow the ceramic heating device at the end remote from the combustion chamber.

Abstract: A spark plug according to this invention includes an insulator having a center through-hole formed therein, a center electrode held in the center through-hole, a metallic shell holding the insulator by swaging, and a ground electrode electrically connected to the metallic shell and defining a spark discharge gap in cooperation with the center electrode. The metallic shell has a male-threaded portion formed on the outer circumferential surface of a front end portion of the metallic shell, and a tightening portion formed on the outer circumferential surface of the metallic shell, located at a rear side with respect to the male-threaded portion. The tightening portion has a width-across-flats W of not greater than 14 mm. A cushion material is filled into a space defined by the metallic shell and an insulator to form a cushion-material charged portion. The cushion-material charged portion has an axial length L of from 0.5 mm to 10.0 mm inclusive and a thickness M of from 0.5 mm to 1.3 mm inclusive.

Abstract: In insulator including alumina as a main component, a Na component in the insulator is set in the range of 0.07 to 0.5 wt % as Na2O. While the Na component content is as high as to have conventionally been regarded to be beyond the common sense, with this range of the Na component content, insulation resistance, mechanical strength and the like at high temperature are unexpectedly not reduced and an insulator with performances comparable to those of an insulator from conventional low soda alumina lower in Na component content than the above described range can be obtained. As a result, medium soda alumina and regular soda alumina that are much lower in cost than conventionally used low soda alumina can be used instead of the low soda alumina, so that dramatic reduction in production costs of insulator 2 for a spark plug 100 and in addition, of the spark plug 100 using the insulator 2 are realized.