Abstract: A metal shell for a spark plug is made from a steel material that has increased carbon content and, in some embodiments, boron as well. The steel material is well-suited for extrusion because of its ductility, while maintaining requisite strength. The spark plug shell may have a reduced outer diameter (ODHL) at a crimped hot lock region, such as the case when the shell is used in smaller diameter spark plugs, such as M8 and M10 plugs. According to a non-limiting example, the spark plug shell steel material comprises 0.20-0.55 wt % carbon, inclusive.
Abstract: A spark plug including a center electrode that has a large-diameter portion having an outside diameter that is largest in the center electrode. The large-diameter portion is retained at a rear facing surface in an axial hole of an insulator. A metal shell has a diameter increased portion on a rear end side with respect to the center electrode, the diameter increased portion having an inside diameter that is increased toward the rear end side. The insulator has a first portion which is a portion of the insulator in a region from a rear end of the rear facing surface to a front end of the diameter increased portion. The first portion has a thickness that is the largest in the region, and is disposed at least on an outer periphery of the large-diameter portion.
Abstract: A spark plug includes a terminal electrode extending in an axial direction of the spark plug. The terminal electrode has an end in the axial direction, and has a recess formed in the end of the terminal electrode. The recess has a bottom surface and an identifier on the bottom surface. The recess has a side surface parallel to the axial direction.
Abstract: A spark plug including a housing, an insulator, a center electrode, and a ground electrode situated at a combustion chamber-side end of the housing. The insulator has an insulator collar, an insulator base, and a transition area, which rests on a projection of the housing. A breathing space is configured at the combustion chamber-side end of the spark plug and is delimited by a section of the inner side of the housing and a section of the insulator base. The section of the insulator base has a rounding including a first leg length and a second leg length angled with respect to the first leg length, the first leg length extending between the intersecting point of the leg lengths with one another and a first end point of the rounding, and the second leg length extending between the intersecting point and a second end point of the rounding.
December 10, 2019
Date of Patent:
July 19, 2022
Robert Bosch GmbH
Felix Traub, Matthias Blankmeister, Sergej Subkow, Stephan Kaske
Abstract: The present invention relates to a spark plug extension body connecting an ignition coil with a spark plug for a spark ignited internal combustion engine, as well as a method for providing such a spark plug extension body for reduction of partial electrical discharges in the spark plug extension body. In conventional spark plug extensions are coil springs used as electrical conductor against the spark plug terminal and/or ignition coil terminal. These coil springs cause Corona effects and short circuiting requiring replacement of the spark plug extension. With the invention the entire electrical conductor (CRu, 64, CRL) is in a rod like form and at least both ends (CRu, CRL) of the electrical conductor (CRu, 64, CRL) are made as a monolith in a flexible and electrically conducting polymeric material, preferably electrically conducting rubber.
Abstract: A prechamber spark plug for an internal combustion engine with the following features: a body with an external thread at its front end for screwing the spark plug into the engine; the external thread has a center line and begins with a thread start at the front end; the body has a passage in which an insulator is fastened and a center electrode protrudes from the front end of this insulator; at the front end of the body, a prechamber-forming cap is provided, which delimits a prechamber and shields the center electrode from a combustion chamber of the engine after the spark plug has been installed in the engine; the cap has at least one opening, which has a predefined orientation in relation to the thread start and is oriented obliquely to the center line of the external thread so as to permit a gas exchange between the prechamber and the space outside the prechamber.
Abstract: An active prechamber device may include a prechamber housing longitudinally aligned with a main axis. The active prechamber device may also include a prechamber nozzle forming a cap at an end of the prechamber housing. The prechamber nozzle and prechamber housing may define a prechamber space that extends along the main axis. The prechamber nozzle may have a plurality of orifices fluidly connected to the prechamber space. Additionally, a fuel injector may be in a linear arrangement with the prechamber housing along the main axis. The fuel injector may have a fuel injection nozzle positioned to spray a fuel into the prechamber space. An electrode arrangement may be formed within the prechamber space. The electrode arrangement may include an electrode shaft and an electrode ring. The electrode ring may circumscribe the electrode shaft to form a spark gap within the prechamber space.
Abstract: A spark plug for an automotive engine includes a shell housing, and an insulator within the shell housing but extending axially beyond the shell housing. A terminal, referred to herein as a cup post terminal, is fixed to the proximal end of the insulator. The cup post terminal includes an engagement surface configured to engage an ignition coil spring for energy transfer to initiate a spark. The cup post terminal includes a sidewall extending axially from the engagement surface. The sidewall cooperates with the engagement surface to define a pocket for the ignition coil spring. The sidewall can have drainage openings to allow oil or contaminants to escape the pocket and drain away from the engagement between the engagement surface and the ignition coil spring. The engagement surface can also be sloped to facilitate the drainage toward the drainage openings.
January 13, 2021
Date of Patent:
September 21, 2021
DENSO INTERNATIONAL AMERICA, INC.
Jeongung Hwang, Harrison Boll, Christopher Thomas
Abstract: A cylinder head is formed with a pre-chamber surrounded by a thin pre-chamber wall sticking out from the inside wall surface of the cylinder head to the inside of the main combustion chamber. Inside of the pre-chamber, the electrode of a spark plug is arranged. When the spark plug is used to burn the air-fuel mixture in the pre-chamber, jet flames are ejected from the communication holes to the main combustion chamber. The thin pre-chamber wall is formed from a metal material while the overall outer circumferential surface around the communication holes passing through the thin pre-chamber wall is formed by a material with a lower heat conductivity than the thin pre-chamber wall.
Abstract: A spark plug has a housing, an insulator, a central electrode and a ground electrode. A projection part is formed projecting radially from the housing. The spark plug has a structure which satisfies a relationship of t2/t1?0.85, s1?0.5, and s1?1.05?t2/t1. A leg part of the insulator has a first end and a second end in an axial direction thereof. The second end is located opposite to the first end in the axial direction. In the relationship, t1 represents a first radial thickness of the first end in a radial direction of the leg part, t2 represents a center radial thickness in the radial direction at a middle position of the leg part, and s1 represents a first gap width in the radial direction of the housing between the projection part of the housing and the first end of the leg part.
Abstract: An ignition plug includes a tubular insulator, a metallic shell disposed around the outer circumference of the insulator, a center electrode disposed in an axial hole of the insulator, and a ground electrode connected to the forward end of the metallic shell and facing the center electrode. The metallic shell has a threaded portion to be engaged with an internal combustion engine. The relational expression Ss/(Sa+Sb)?2.6 is satisfied, where Ss is the surface area of an outer circumferential surface of the metallic shell extending from the rear end of the threaded portion to the forward end of the threaded portion, Sa is the surface area of that portion of the metallic shell which is to be exposed to combustion gas of the internal combustion engine, and Sb is the surface area of that portion of the insulator which is to be exposed to the combustion gas.
Abstract: A spark plug includes an insulator, a housing, and a deformable sealing washer disposed between the insulator and the housing, the insulator having an annular full-perimeter shoulder against which the sealing washer rests, and the shoulder having a radius in a range of between 0.20 mm and 0.60 mm.
Abstract: An ignition device for an internal combustion engine is provided which includes a spark plug and a controller. The spark plug has a housing with a head protruding into a combustion chamber of the engine. The head has at least a portion located downstream of a spark gap of the spark plug in an air-fuel mixture flow within the combustion chamber. The controller works to perform a plurality of discharge events in the spark plug in each cycle of an operation of the engine. This improves the ability of the spark plug to ignite the mixture without need to increase an ignition energy.
Abstract: A pre-chamber spark plug for an internal combustion engine having a surface discharge spark gap that is generally located at a rearward end of a pre-chamber and is configured so that sparking components will have minimal electrode obstruction and promote unhindered gas exchange between the pre-chamber and a main combustion chamber. According to one embodiment, the surface discharge spark gap includes a radial sparking portion where a majority of the sparking occurs in a generally radial direction. According to another embodiment, the surface discharge spark gap includes both a radial sparking portion and an axial sparking portion so that sparking occurs in both radial and axial directions, respectively.
Abstract: A corona igniter (20) includes a metal shell (32) with a corona reducing lip (38) spaced from an insulator (26) and being free of sharp edges (40) to prevent arcing (42) in a rollover region and concentrate the electrical field at an electrode firing end (48). The corona reducing lip (38) includes lip outer surfaces (88) being round, convex, concave, or curving continuously with smooth transitions (90) therebetween. The corona reducing lip (38) includes lip outer surfaces (88) presenting spherical lip radii (rl) being at least 0.004 inches. The corona igniter (20) also includes shell inner surfaces (104) and insulator outer surfaces (75) facing one another being free of sharp edges (40).
Abstract: An electrode material is composed of at least 0.2 mass % and at most 1.0 mass % of Y, at least 0 mass % and at most 0.2 mass % of Al, at least 0.2 mass % and at most 1.6 mass % of Si, at least 0.05 mass % and at most 1.0 mass % of Cr, at least 0.05 mass % and at most 0.5 mass % of Ti, at least 0.1 mass % and at most 0.5 mass in total of one or more elements selected from among Yb, Sb, Ir, Zr, Hf, Pt, Re, Pd, Rh, Ru, Nb, V, W, Mo, and Ta, and a remainder composed of Ni and an inevitable impurity.
October 31, 2016
Date of Patent:
June 18, 2019
Sumitomo Electric Industries, Ltd., DENSO CORPORATION
Abstract: An alumina-based sintered body includes 92 mass % to 96 mass % of Al in terms of an oxide, and at least three elements selected from Group II elements, one of the at least three elements being 1.90 mass % or more of Ba in terms of an oxide. The alumina-based sintered body includes the following phases in a grain boundary phase present between alumina crystal grains: a first crystal phase containing Si and at least one of the Group II elements, and a second crystal phase containing Al and at least one of the Group II elements. In X-ray diffraction of the alumina-based sintered body, the maximum relative intensity of the first crystal phase and the maximum relative intensity of the second crystal phase are both 2 or above relative to the maximum diffraction intensity of the alumina crystal.
Abstract: A spark plug having a ceramic insulator held by a crimp portion of a metallic shell. The crimp portion satisfies a relation of A?1.7 mm and a relation of t?1.20 mm in a cross section of the crimp portion taken along a plane containing the axial line, where A is the distance between a closest point which is a point within the cross section closest to the ceramic insulator and an intersection at which a first orthogonal line passing through the closest point and orthogonal to the axial line intersects with an outer circumference of the crimp portion, and t is a thickness of the proximal end of the crimp portion.
Abstract: A spark plug having an insulator with a front end portion having an annular groove opened to a front side around an axial line. The groove has a width of greater than or equal to 0.2 mm in a radial direction. In a cross section including the axial line, a value D/L obtained by dividing, by a length L, a creepage distance D, from a position P on the frontmost side of a region in which a clearance distance between an outer surface of a front end portion and an inner circumferential surface of a metal shell is less than or equal to 0.1 mm to a connection position between an outer surface of the front end portion and the axial hole, is greater than or equal to 1.1.
Abstract: A spark plug includes an insulator having an axial hole formed in a direction of an axis, a center electrode held in one end side of the axial hole, a metal terminal held in the other end side of the axial hole, an electrical connection part arranged to establish electrical connection between the center electrode and the metal terminal within the axial hole, and a metal shell disposed around an outer circumference of the insulator and having a thread portion formed on at least a part of an outer circumferential surface thereof. The electrical connection part has a resistor, and a conductive seal layer provided between the resistor and the center electrode to seal and fix the insulator and the center electrode together. In a half or more of a region in which the seal layer is provided in the direction of the axis, the spark plug satisfies predetermined conditions.
Abstract: A spark plug includes a cylindrical metallic shell having a ground electrode at a forward end of the cylindrical metallic shell, a cylindrical insulator held in the metallic shell, a center electrode disposed in the insulator, a resistor element disposed in the insulator and having a forward end located rearward of a rear end of the center electrode, a forward-end-side electrically conductive seal layer disposed in the insulator to be located between the center electrode and the resistor element, and a rear-end-side electrically conductive seal layer disposed in the insulator to be located rearward of the resistor element. The forward end of the resistor element is located forward of the rear end of the metallic shell, and the rear end of the resistor element is located rearward of the rear end of the metallic shell.
Abstract: An igniter includes a central electrode terminating in a firing portion including a plurality of prong tiers distributed axially on the firing portion. Each prong tier including at least one firing prong extending radially outward from the firing portion. The igniter body includes a port end to be received into an engine igniter port, and a shank. The firing portion of the central electrode extends from the shank opposing the port end. A dielectric casing can fully encapsulate the firing portion of the central electrode to define a dielectric barrier adjacent the firing prong. The igniter may include a generally cylindrical ground electrode defining a discharge cavity surrounding the central electrode. The ground electrode includes a plurality of ground prongs defined by the ground electrode and extending radially toward the firing portion. A plurality of apertures defined by the ground electrode are in fluid communication with the discharge cavity.
February 24, 2015
Date of Patent:
April 24, 2018
GM Global Technology Operations LLC
Cherian A. Idicheria, Paul M. Najt, Laxminarayan L. Raja
Abstract: A method for manufacturing a spark plug comprises: welding a ground electrode to a tip of a metal shell (metallic shell); and removing a welding sag formed on and over inner surfaces of the ground electrode and the metal shell from a work in which the ground electrode is welded to the tip of the metal shell, the welding step including: cutting the welding sag using a working tool while a control unit controls a working position of the working tool with respect to the work; and measuring a remaining quantity of the welding sag after the cutting step and the control unit performing a feedback of a measured value of the remaining quantity of the welding sag measured in the measuring step to a working position of a working tool in the cutting step for the subsequent work.
Abstract: An electrically conductive glass seal for providing a hermetic bond between an electrically conductive component and an insulator of a spark plug 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 90.0 weight (wt. %), and electrically conductive metal particles in an amount of 10.0 to 50.0 wt. %, based on the total weight of the glass seal.
August 1, 2016
Date of Patent:
February 13, 2018
Keith Firstenberg, William J. Walker, Jr.
Abstract: A pair of electrode lugs clamp a bar at side surfaces of the bar so as to be electrically connected to the bar. The electrode lugs respectively include a first contact portion and a second contact portion having different front-back lengths. The bar is clamped such that the first contact portion having a short front-back length L1 opposes a back end portion of the bar within a range of the second contact portion having a front-back length L2. The back end surface of the bar is brought into contact with and welded to a front end surface of a metal shell by resistance butt welding. Since the first contact portion of one lug is short and is close to the abutting surfaces, heat dissipation can be reduced and heat concentration can be increased.
Abstract: A spark plug may include a center electrode disposed in a center portion of the spark plug, an insulator surrounding the center electrode, and a metal shell surrounding the insulator and having a ground electrode extending downwards from a lower end of the metal shell and an inner surface facing the insulator, the inner surface being concavely shaped to form a shielding space between the concavely shaped portion of the inner surface and the insulator for adjusting a heat range of the spark plug.
Abstract: An electrically-conductive seal portion of a spark plug includes a large-diameter seal portion, a small-diameter seal portion having an outer diameter smaller than an outer diameter of the large-diameter seal portion, and a tapered seal portion disposed between the large-diameter seal portion and the small-diameter seal portion. An insulator includes a flange portion, a first middle-body portion having an outer diameter smaller than an outer diameter of the flange portion, a second middle-body portion having an outer diameter smaller than an outer diameter of the first middle-body portion, and a leg portion having an outer diameter that tapers toward a tip end of the spark plug. The tapered seal portion is disposed inside the first middle-body portion.
Abstract: A spark plug having a housing, an insulator disposed in the housing, a center electrode situated in the insulator, a ground electrode disposed on the housing, and at least one sealing element, the at least one sealing element being situated on the housing, in particular between the insulator and the housing, wherein the at least one sealing element is made from an at least ternary alloy, and the alloy contains copper as the main constituent.
Abstract: A spark plug includes a housing, an insulator inside the housing, a center electrode inside the insulator, and a connecting pin inside the insulator. At least one fillet is formed at a change of cross section at the housing, at the insulator, at the center electrode, and/or at the connecting pin. The fillet, viewed in cross section, includes a first leg and a second leg at an angle to the first leg. The length of the first leg is greater than the length of the second leg.
Abstract: A corona igniter (20) includes a metal shell (32) with a corona reducing lip (38) spaced from an insulator (26) and being free of sharp edges (40) to prevent arcing (42) in a rollover region and concentrate the electrical field at an electrode firing end (48). The corona reducing lip (38) includes lip outer surfaces (88) being round, convex, concave, or curving continuously with smooth transitions (90) therebetween. The corona reducing lip (38) includes lip outer surfaces (88) presenting spherical lip radii (r1) being at least 0.004 inches. The corona igniter (20) also includes shell inner surfaces (104) and insulator outer surfaces (75) facing one another being free of sharp edges (40).
Abstract: A spark plug having a resistor disposed within a through hole of an insulator and between a center electrode and a metal terminal so as to be spaced apart from the center electrode in a direction of an axial line; and a conductive glass seal layer provided between the resistor and the center electrode and electrically connecting the resistor and the center electrode to each other, the conductive glass seal layer has a diameter of 3.9 mm or less, and a joined surface of the conductive glass seal layer and the resistor has a convex shape toward the center electrode side. A length ? from a rear end to a front end of the joined surface and a maximum length ? of the conductive glass seal layer in the direction of the axial line meets a relation of ?/??0.4.
Abstract: A spark plug includes an insulator and a center electrode. The insulator includes: a first cylindrical portion; a truncated cone-shaped portion whose outer diameter reduces toward a front end side; and a second cylindrical portion formed at a front end side of the truncated cone-shaped portion. A diameter C of the center electrode is not larger than 2.2 mm. A total I of a volume of the truncated cone-shaped portion and a volume of the second cylindrical portion, a volume E of the center electrode from a position at a rear end of the truncated cone-shaped portion to a position at a front end of the second cylindrical portion, and the diameter C satisfy I/E?4.2333C2?19.79C+24.869.
Abstract: A spark plug including an insulator containing not less than 92 mass % and not greater than 96 mass % of Al component in terms of oxide, wherein the insulator is formed from an alumina sintered body comprising alumina crystal and a grain boundary phase present between crystal grains of the alumina crystal. Assuming that mass contents of an Si component, an Mg component, a Ba component, and a Ca component in terms of oxide are represented by MSiO2, MMgO, MBaO, and MCaO, respectively, and a sum of MSiO2, MMgO, MBaO, and MCaO is represented by Mt, the grain boundary phase contains these components so as to satisfy conditions (1) to (4) as follows: (1) 0.17?MSiO2/Mt?0.47; (2) 0.005?MMgO/Mt?0.07; (3) 0.29?MBaO/Mt?0.77; (4) 0.03?MCaO/Mt?0.19.
Abstract: An insulator used in a spark plug having improved strength and dielectric strength performance. The insulator comprises a sintered compact whose main constituent is alumina. In the sintered compact, a content ratio of a rare earth element (R. E.) and a group 2 element (2A) satisfies 0.1?R. E./2A ?1.4, and the content ratio of the R. E. and barium oxide (BaO) satisfies 0.2?BaO/R. E.?0.8. At least one virtual rectangular frame of 7.5 ?m×50 ?m surrounding crystals containing the rare earth element lies within a region of 630 ?m×480 ?m in any cross section of the sintered compact.
Abstract: A spark plug wherein an outer diameter of a first face that is a gap foliating face of the center electrode tip is denoted as R1, an outer diameter of a second face that is a gap forming face of the ground electrode tip is denoted as R2, a length of the gap is denoted as G1, and an average distance of a distance between an end in the first direction of the first face and an end in the first direction of the second face and a distance between an end in the second direction of the first face and an end in the second direction of the second face is denoted as G2, R1<R2, 0.5 mm?R1?1.1 mm, 0.7 mm?R2?1.2 mm, 0.6 mm?G1?1.3 mm, and 1.4?(R2/R1)×(G2/G1)?1.8 are satisfied.
Abstract: An ignition plug includes a tubular ceramic insulator and a metallic shell having a protrusion protruding radially inward. The ceramic insulator has an engagement portion which is engaged with a receiving surface of the protrusion and an intermediate trunk portion extending rearward from the rear end of the engagement portion. A?1.70 and B ?1.20 are satisfied, where A is the thickness (mm) of the metallic shell along a direction which passes through the center of the receiving surface and is orthogonal to the axial line on a cross section including the axial line, and B is the minimum thickness (mm) of the metallic shell 3 at the tube portion along the direction orthogonal to the axial line.
Abstract: A spark plug includes an insulator; a center electrode; a metallic shell; a ground electrode disposed at a forward end portion of the metallic shell and forming a gap in cooperation with a forward end portion of the center electrode; and a tip at least a portion of which is joined to at least the one of two side surfaces of the ground electrode which is disposed downstream with respect to fuel gas flow. In a first imaginary plane which contains a forward end surface of the center electrode and on which a discharge surface of the tip is projected, at least a portion of a projected image of the discharge surface is located within a range of 2.5G from the outer circumference of the forward end surface of the center electrode, where G (mm) is the size of the gap.
Abstract: A spark plug has a metal shell and a cylindrical ceramic insulator disposed in an inner circumference of the metal shell. An axial hole extends in an axial line CL direction through the insulator, and has a tip located more to a tip side of the spark plug than a tip of the metal shell, and a distance along the axial line CL1 from the tip of the metal shell to the tip of the ceramic insulator is 0.5 mm or more. The insulator satisfies C ?1.07 mm and V ?3.9 mm3, where C is a thickness of the insulator in a cross section passing an inner circumference surface tip of the metal shell and orthogonal to the axial line CL1 ,and V is a volume of the ceramic insulator within a range of 0.5 mm from the tip of the ceramic insulator to a rear end side in the axial line CL1 direction.
Abstract: Provided is a technique which realizes securement of gas-tightness and suppression of loosening of a gasket. A spark plug includes a tubular metallic shell extending in an axial direction, and an annular gasket provided around the metallic shell. The gasket is solid and contains copper as a main component and nickel in an amount of 0.1 wt. % or more. The gasket has a maximum thickness of 0.4 mm or more in the axial direction, and the gasket has a Vickers hardness of 30 HV to 150 HV.
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: Adhesiveness between a metallic substrate and a metal oxide layer is made to increase. A superconducting thin film (1) includes a metallic substrate (10), a metallic layer (22) that is formed on a main surface of the metallic substrate (10) and includes a metal element capable of being passivated as a main component, a metal oxide layer (24) that is formed on the metallic layer (22) and includes the passivated metal element as a main component, and a superconducting layer (40) that is formed on the metal oxide layer (24) directly or through an intermediate layer and includes an oxide superconductor as a main component.
Abstract: A corona igniter (20) for emitting a radio frequency electric field and providing a corona discharge (24) includes a central electrode (22) at a positive voltage, a grounded metal shell (30), and an insulator (28) with an abruption (34) extending radially outward relative to the central electrode (22). The abruption (34) is typically an increase of at least 15% of a local thickness (t) of the insulator (28) over less than 25% of a nose length (el) of an insulator nose region (74). The abruption (34) is typically one flank (82) of a protrusion or a notch, and the flank (82) faces the shell (30). The abruption (34) reverses the electric field and voltage potential gradient along the insulator outer surface (32), repels charged ions away from the insulator (28), and thus prevents the formation of a conductive path between the central electrode (22) and the shell (22).
Abstract: An igniter (20) includes an outer insulator (24) formed of an outer ceramic material hermetically sealed to a conductive core (26). The conductive core (26) is formed of a core ceramic material and a conductive component, such as an electrically conductive coating applied to the core ceramic material or metal particles or wires embedded in the core ceramic material. The conductive core (26) is typically sintered and disposed in the green outer insulator (24). The components are then sintered together such that the outer insulator (24) shrinks onto the conductive core (26) and the hermetic seal forms therebetween. The conductive core (26) fills the outer insulator (24), so that the conductive core (26) is disposed at an insulator nose end (34) of the outer insulator (24) and the electrical discharge (22) can be emitted from the conductive core (26), eliminating the need for a separate firing tip.
Abstract: There is provided a spark plug for an internal combustion engine, including: a center electrode extending in the direction of an axis of the spark plug and having a core of higher thermal expansion coefficient than that of a front end thereof, the center electrode including a flanged portion radially outwardly protruding on a rear side thereof and a cylindrical portion located closer to a front end of the spark plug than the flanged portion and being smaller in diameter than the flanged portion; an insulator having an axial hole in the direction of the axis to retain the flanged portion in the axial hole with the cylindrical portion held in a loose-fit state in the axial hole; and a metal shell accommodating the insulator, wherein the spark plug satisfies the following condition: Cb<Cf where Cb is a difference between an inner diameter of the axial hole and an outer diameter of the cylindrical portion at an arbitrary axial position B in the direction of the axis; and Cf is a difference between the inner di
Abstract: A spark plug includes an insulator, a terminal electrode, a center electrode, a resistor, and a glass seal layer. The terminal electrode has: a recess part opened to the front end side and having a depth in a center axis direction of the terminal electrode; and a flat part neighboring the recess part at its outer circumference side. The relationship 0.52?B/A?0.91 is satisfied, wherein A (mm2) represents an area of a region surrounded by an outline of an outer circumference surface of the terminal electrode, and B (mm2) which represents an area of a region of the terminal electrode surrounded by an outline of an inner surface of the recess part, in a cross section orthogonal to the center axis and located 0.1 mm away from a front end along the center axis to the rear end side.
Abstract: A spark plug with a particular configuration, particularly in the area of a gasket that seals between a shell and insulator, increases the mechanical strength of the spark plug and helps prevent breaking, cracking and/or other failures in the insulator. The spark plug is designed such that the shell, insulator and gasket, which may be in the form of a sleeve-like cylindrical gasket or a ring-like annular gasket, work together to provide better support for the insulator against axial and/or radial stresses. This improved support can offset certain stresses, such as radial stress RS that can be exerted against the insulator core nose when the engine experiences knocking or misfiring.
Abstract: An ignition plug having a ceramic insulator with an axial bore, a metallic shell provided around the ceramic insulator, and a terminal electrode having a leg portion inserted into a rear end portion of the axial bore and a head portion projecting from the rear end of the ceramic insulator, wherein the length L of a portion of the ceramic insulator projecting from the rear end of the metallic shell is not less than 28 mm but not greater than 34 mm. The thickness t of the thinnest portion of the ceramic insulator is 1.0 mm or greater within a region which extends 5.5 mm from the rear end of the ceramic insulator toward the forward end side with respect to the direction of the axis.
Abstract: A spark plug for a stationary, gas-powered internal combustion engine, having a metallic body, an insulator mounted in a passage of the body, a center electrode passing through the insulator, a ground electrode mounted on the body that, together with the center electrode, forms a spark air gap, and a cap attached to the body. The cap shields the center and ground electrodes from the combustion chamber after the spark plug is installed in a combustion chamber of the internal combustion engine, and that, together with the body of the spark plug, forms a prechamber in which the center and ground electrodes are located. The cap has at least one opening that permits gas exchange between the prechamber and the space outside of the prechamber.
Abstract: An ignition plug includes an insulator having an axial hole extending therethrough in the direction of an axis, a center electrode inserted into a forward end portion of the axial hole, and a metallic shell disposed externally of the insulator. The insulator includes a step portion engaged with an inner circumferential portion of the metallic shell and a leg portion extending forward from the forward end of the step portion. The porosity of the leg portion is 3.0% or less. Among three regions of the leg portion that are radially trisected in a cross section perpendicular to the axis, the outermost region is defined as a first region and the innermost region is defined as a second region. The porosity of the first region is equal to or more than 1.20 times the porosity of the second region.
Abstract: A spark plug includes a metal shell and a gasket. The metal shell includes a thread portion, a seat portion, and a thread root portion. The gasket has an inner diameter smaller than a thread size of the thread portion. The relationships 0.8L?C?L?2A and B?0.75L are satisfied in a case where: in the seat portion, an outer diameter of a seating portion is L (mm); the maximum value of a relatively shiftable distance is A (mm), the gasket is shiftable along a direction orthogonal to the axis relative to the metal shell by the maximum value; in the gasket, an outer diameter is C (mm); and in the gasket, an inner diameter is B (mm).