Ngk Spark Plug Company, Limited

Honda Giken Kogyo Kabushiki Kaisha

Mitsutaka Yoshida

Junichi Kagawa

Kanemitsu Nishio

Minoru Ando

Akio Sakura

Yoshiaki Saiki

Toru Moriya

Takashi Suzuki

Makoto Sugimoto

Shunichi Takagi

Yutaka Tanaka

Masao Sakai

Akihiro Toya

Toshikazu Kawakami

Eigo Goto

Junji Sunohara

Akihisa Harada

Tunekazu Enomoto

By heating a glass sealing material, a center electrode is sealed and fixed within an axial bore of an insulator. Formation of a groove in a head portion of the center electrode makes it possible to protect the head portion of the center electrode from deformation under a pressure which is applied upon filling the glass sealing material in a powder form in the axial bore. The glass sealing material is therefore assured to flow to a peripheral side wall of a flange portion of the center electrode, thereby enhancing mechanical engagement between the center electrode and the insulator, that is, uniting strength for them. A spark plug is hence obtained with improved impact resistance and accordingly, with sufficient durability.

Spark plug for internal combustion engine

In a package box for a plurality of spark plugs, a paper tray has an array of lower cellular boxes provided to accommodate lower portions of spark plugs to protect their spark gaps against dimensional alteration, and an array of upper cellular boxes provided to retain upper portions of the spark plugs in place. A casing package is provided to accommodate the paper tray. The lower cellular boxes have circular crease lines each about the size so that Individual thread portions of the spark plugs are to be inserted, and having a plurality of incision lines provided to be oriented radially toward central portions of the circular crease lines. Accommodation holes are formed with pluralistic tabs by expanding the incision lines and bending along the circular crease lines so as to accommodate the thread portions of metallic shells of the spark plugs with the thread portions supportably engaged by the tabs when forcing outer electrodes and the thread portions of the spark plugs against sections surrounded by the circular crease lines. The upper cellular boxes have upper open ended U-shaped retainer holes to admit the head portions of insulators of the spark plugs so that the tray accommodates the spark plugs with the insulators exposed between the array of the upper and lower cellular boxes.

Package box for a spark plug

In a spark plug, a tubular insulator has an axial bore in which a center electrode and a terminal electrode are axially aligned, the terminal electrode having a seal portion fixedly supported by partly filling the axial bore with a glass sealant. The insulator further has a tapered shoulder portion between a diameter-reduced portion and a diameter-increased portion, each provided on the insulator. A metallic shell is placed around the diameter-increased portion of the insulator, a rear end of the metallic shell being caulked against the diameter-reduced portion of the insulator, a space between the metallic shell and the diameter-reduced portion of the insulator being filled with a ceramic powder. An inclination of the tapered shoulder portion of the insulator ranges from 10 to 45 degrees against a plane perpendicular to the terminal electrode. A roulette is formed on an outer surface of the seal portion of the terminal electrode in which the glass sealant is filled. A front end of the seal portion of the terminal electrode is located in the range of +5.0 mm to -1.0 mm from a boundary where the tapered shoulder portion meets the diameter-increased portion of the insulator.

Spark plug for an internal combustion engine

A spark plug for an internal combustion engine includes a metallic shell within which a tubular insulator is placed, a center electrode is provided within the insulator to form a spark gap between a front end of the center electrode and an outer electrode extending from the metallic shell. First and second stepped portions are provided near a front portion of the center electrode to form a clearance between an outer wall of the center electrode and an inner wall of the insulator. The stepped portions have a progressively decreasing diameter toward the front end of the center electrode. A tapered portion is provided at an inner wall of the insulator by bevelling a front open end of the insulator. This maintains high insulation of the insulator with significantly low carbon deposit, thus avoiding ignition failure of the spark plug.

Spark plug for use in internal combustion engine

A spark plug for an internal combustion engine is disclosed. A semiconductor material having a resistance of 5.times.10.sup.2 -5.times.10.sup.4 M.OMEGA./mm is coated or baked in the form of a band on the peripheral surface of a basal part of a leg portion of an insulator of the spark plug. Preferably, at least the basal part of the leg portion, including the band, is covered with a water-repellant insulating coating. An inner wall of a metal shell of the spark plug is desirably coated with a water-repellant material at an area facing at least the peripheral surface of the basal part of the leg portion of the insulator.

In a center electrode structure for spark plug including a tubular insulator, the inner side of which has a stepped shoulder to provide a diameter-reduced bore therein; a center electrode having a flange, and concentrically placed into the insulator with the flange engaging against the shoulder, and with one end being axially through the bore so as to be exposed to outside of the insulator; the center electrode having a highly heat conductive core of copper or copper-based alloy which is encased into an enclosure made of oxidation and heat resistant nickel-based alloy; and the core providing its overall outer surface with a thin oxidation layer, so that the core is clad with the enclosure through the oxidation layer by means of extrusion.

Center electrode structure for spark plug

In a center electrode structure for spark plug including a tublar insulator, the inner side of which has a stepped shoulder to provide a diameter-reduced bore therein; a center electrode having a flange, and concentrically placed into the insulator with the flange engaging against the shoulder, and with one end being axially through the bore so as to be exposed to outside of the insulator; the center electrode having an electrically conductive core of copper or copper-based alloy which is encased into an enclosure made of oxidation and heat resistant nickel-based alloy; and the core being provided with a number of fractures in its granular structure so as to absorb thermal stress due to the thermal expansional difference between the core and enclosure.

A spark plug incorporating a winding type inductor has a low noise level from a low frequency range to a high frequency range. The spark plug comprises a ceramic insulator having a bore, a metal fitting surrounding the insulator, a center electrode, a terminal electrode and a noise-attenuation element arranged in the bore of the ceramic insulator and sealed to the center and terminal electrodes through glass, said noise-attenuation element consisting of an inductance component alone or a combination of an inductance component and a resistance component, and said inductance component being arranged extending to both sides of a sealed level for the noise-attenuation element formed by an end of the metal fitting which is connected to the insulator.

Spark plug having a low noise level

An internal combustion engine ignition device comprises a radio noise preventing device for suppressing the capacity discharge current which flows in the low voltage side circuit of an ignition circuit and is generated during the spark discharge of a spark plug in order to prevent the radio noise generated by the ignition system of the internal combustion engine.

Internal combustion engine ignition noise preventing device

A device for suppressing disturbance electric wave for motorcycles is disclosed. The device makes use of a flexible wire for connecting a ground terminal of a secondary winding of an ignition coil to a ground terminal of an ignition plug.

Device for suppressing disturbance electric wave for motorcycles

A self sealable glassy resistor composition for a resistor sealed spark plug consists essentially of 5-40% by weight of at least one of the resistance value stabilizing component selected from the group consisting of oxides of metals of Groups IVb and Vb of the Periodic Table and rare earth metals, ThO.sub.2 and SiC, a water soluble carbonaceous material of saccharides or aliphatic hydrocarbons in such an amount that 0.1-5.0% by weight of carbon value is contained in the final composition, 35-85% by weight of borosilicate glass powder, 5-25% by weight of at least one of metals or alloys thereof, the melting point of which is higher than the glass seal temperature and 2-20% by weight of at least one of metals or alloys thereof, the melting point of which is lower than the glass seal temperature, provided that the total amount of both the higher melting point metals or alloys and the lower melting point metals or alloys is up to 30% by weight. The properties of the self sealable glassy resistor composition can be improved by additionally adding 0.1-20 parts by weight based on 100 parts by weight of the self sealable glassy resistor composition, of at least one of the carbides of Ti, Zr, V, Nb, Ta, Cr, Mo, W, B and Th.

Growing community of inventors

Nagoya, Japan

Mitsutaka Yoshida