Ngk Spark Plug Company, Limited

Ngk Spark Plug., Ltd.

Mamoru Musasa

Akira Suzuki

Tomoaki Kato

Naomichi Miyashita

Kazuyoshi Torii

Hiroyuki Tanabe

Makoto Sugimoto

Masahiro Konishi

Wataru Matsutani

Osamu Yoshimoto

Jiro Kyuno

Hideki Teramura

Tomoo Tanaka

Mai Nakamura

Yuichi Nakano

Takafumi Oshima

Yoshihiro Matsubara

Toshitaka Honda

Hiroyuki Kameda

Junichi Kagawa

Tsutomu Shibata

Hiroaki Kuki

Masayuki Segawa

Tsutomu Okayama

Kazuya Iwata

Mai Moribe

Kenji Moritani

Hirotoshi Yoshizaki

Kiyohiro Kondo

Konishi Masahiro

Sugimoto Makoto

A spark plug capable of preventing a separation of a noble metal tip and capable of extending a service-life of the spark plug.

Spark plug for internal combustion engine and method of manufacturing the same

A gasket for use around a thread neck of an automotive component, the gasket dimensioned to prevent the gasket from falling off of the thread neck and to prevent a male screw portion from biting into the gasket.

Gasket and automotive component

In process of threadably fitting a metal shell having a surface formed with an Ni plated layer into a mounting hole, in a state where a gasket made of stainless steel is uncompressed while being interposed between a protrusion part and an opening periphery, a surface of the gasket is out of contact with another surface thereof. When the gasket is viewed on a cross section in a direction of an axial line O, the gasket contacts with the protrusion part at one point of a point X, the gasket contacts with the opening periphery flat one point of a point Y, and the point Y is located outside of the point X in a radial direction. Further, the point Y is located inside of a maximum outer diameter Dz of a seating surface of the protrusion part in the radial direction.

Spark plug

Problem is to enhance the welding strength when a projecting shape section is resistance-welded to a around electrode. A ground electrodeincludes a ground electrode base materialand a projecting shape section. The projecting shape sectionis connected by resistance welding to an opposite surfaceof the ground electrodeso as to be opposite and project towards the leading end of a center electrode. The ground electrode base materialand the projecting shape sectionare formed from a material that is composed of the same metal (for example, nickel) as a main component and have a relation of formulas (1) and (2) described below. In formula (1), the specific resistance of the ground electrode base materialis R (&#x3bc;&#x3a9;cm) and the specific resistance of the projecting shape sectionis S (&#x3bc;&#x3a9;cm). The specific resistance R&#x3e;the specific resistance S . . . (formula 1), the specific resistance R&#x2212;specific resistance S&#x2267;20 . . . (formula 2). Accordingly, fusion of the ground electrode base materialthat has a larger volume than that of the projecting shape sectioncan be expedited and the welding strength can be enhanced.

An object of the invention is to restrain separation of an electrode tip from a ground electrode or from a center electrode. A spark plug satisfies a condition 0.8&#x2266;A1/A2&#x2266;1.9, where, as viewed on a section which contains a center axis (O) of an electrode tip, A1 [Hv] is hardness of the electrode tip as measured outside a circle having a radius of 0.2 mm, with a boundary point (PA) on a surface of the spark plug between a fusion zone and the electrode tip serving as the center of the circle, and A2 [Hv] is hardness of the electrode tip as measured within the circle having a radius of 0.2 mm.

Spark plug having a substantially columnar electrode tip welded to a component thereof

A spark plug includes a center electrode, a ground electrode, and a noble metal tip. The noble metal tip is joined to an object member of at least one of two electrodes via a fusion zone. A projected overlap region of the noble metal tip and the fusion zone accounts for 70% or more of a projected region of the noble metal tip. The object member contains at least Si out of Al and Si such that the amount of Si is 0.4% by mass or higher and such that the total amount of Al and Si is 0.5% by mass. Multi-fusion spots exist on the surface of the fusion zone. Segments of a baseline which pass through the respective multi-fusion spots have a total length of a predetermined percentage of the length of the baseline. Joining strength to the noble metal tip can thereby be greatly improved when the member to be joined contains Si.

Spark plug for internal combustion engine and method of manufacturing the spark plug

[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 () of an insulation member () is loose-fitted into a mating hole portion () of a metallic shell (), a filler () for maintaining gas tightness is charged between the outer circumferential surface of the mating shaft portion () and the inner circumferential surface of the mating hole portion (). Despite the thermal expansion difference, the gas tightness is maintained, because the filler () for maintaining gas tightness is charged between the inner and outer circumferential surfaces.

The present invention provides a spark plug that includes a center electrode extending in an axial direction, a ceramic insulator having an axial hole formed in the axial direction to retain the center electrode in a front side of the axial hole and thereby form an assembly unit of the center electrode and the ceramic insulator, a metal shell surrounding an outer circumference of the ceramic insulator to retain therein the assembly unit, and a ground electrode having one end portion joined to a front end face of the metal shell and the other end portion facing the center electrode to define a spark gap therebetween, wherein the spark plug satisfies the following conditions: H&#x2267;1 mm, Vc&#x2266;17 mmand Ra&#x2267;1.0&#xd7;10K/(m&#xb7;W) where H is a length by which the ceramic insulator protrudes toward the front from the front end face of the metal shell in the axial direction; Vc is a volume of part of the ceramic insulator extending within a range of 2 mm from a front end of the ceramic insulator toward the rear in the axial direction; and Ra is a thermal resistance per unit length, excluding air space, at 20&#xb0; C. at a cross section of the assembly unit taken perpendicular to the axial direction at a position 2 mm away from the front end of the ceramic insulator.

Spark plug having self-cleaning of carbon deposits

To provide a method of producing a spark plug in which a spark discharge gap with a suitable distance can easily be obtained without bending to deform a ground electrode in a direction in which the ground electrode moves towards or away from a metal tip of a center electrode, in the method of producing a spark plug, when a metal tip (a noble metal tip)is welded to a front end portionof a center electrode, the metal tipis welded to the front end portionof the center electrodeafter a state is established in which the metal tipalone is positioned in a radial direction where a predetermined spark discharge gap g is formed relative to a distal end portionof a ground electrodewhich is joined to a metal shellat a proximal end portionthereof.

Method of producing a spark plug

A spark plug () includes an insulator () and a metal shell (), including a middle section () positioned between a collar section () and a tool engaging section (). The middle section () has a bulged section (), a first slender section () and a second slender section () that is the most slender at a portion positioned further to the leading end side than the bulged section (). In a cross-section including the axis CL, when the distance between both slender sections () and () along the axis CLis F (mm) and the bulged amount to the inside in diametrical direction of a most bulged section (M) with respect to an imaginary line that connects a portion that is positioned furthest to the inside in diametrical direction of both slender sectionsandis G (mm), the relationship 0.00&#x3c;G/F&#x2266;0.18 is satisfied.

Spark plug for internal combustion engine and method of manufacturing spark plug

The present invention provides a spark plug which is capable of suppressing a occurrence of crack and separation by determining a structural configuration of a melting portion formed in a junction portion between a discharge portion and a pedestal portion which form an ignition portion that protrudes from a ground electrode. In a profile line shape of a cross section including a center axis P of an ignition portion, an exposure surfaceof a melting portionconnects a side surfaceof a discharge portionand a side surfaceof a pedestal portion. Further, an exterior angle &#x3b8; formed between an imaginary line Q, which passes through a boundary position X1 between the melting portionand the pedestal portionand a boundary position X2 between the melting portionand the discharge portion, and the center axis P at a node C, satisfies 135&#xb0;&#x2266;&#x3b8;&#x2266;175&#xb0;. Furthermore, a proportion T/S of a forming depth T of the melting portionto an outside diameter S of the discharge portionsatisfies T/S&#x2267;0.5.

A spark plug having a center electrode and a ground electrode including a ground electrode main body part having an end thereof facing the center electrode and a noble metal tip joined to the ground electrode main body part at a position facing a leading end of the center electrode, a spark discharge gap being formed between the leading end of the center electrode and the noble metal tip, wherein at least a portion of the ground electrode main body part, to which the noble metal tip is joined, is made of an Ni alloy containing 12 to 45 mass % of Cr, 7 mass % or less of Fe, 0.5 to 5 mass % of Al, 0.3 to 5 mass % of Si and 50 mass % or more of the balance, and wherein the joined portion and the noble metal tip are joined by laser welding or electron beam welding.

Spark plug having a ground electrode of specific alloy composition to which a noble metal tip is joined

A spark plug which provides reliable prevention of adhesion and accumulation of carbon on an insulator, includes a center electrode extending in the direction of an axis CL, a ceramic insulator having an axial hole which extends in the direction of the axis CLand in which the center electrode is provided, a cylindrical metallic shell provided externally of the outer circumference of the insulator and having a support portion formed on the inner circumferential surface thereof, and a ground electrode extending from a front end portion of the metallic shell. The insulator has a stepped portion supported by the support portion of the metallic shell, and a leg portion formed forward of the stepped portion. A space SP formed between the leg portion of the insulator and the inner circumferential surface of the metallic shell has a volume of 100 mmto 300 mminclusive.

Spark plug for preventing accumulation of carbon on an insulator

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.

Easily removable spark plug

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

Growing community of inventors

Nagoya, Japan

Mamoru Musasa