Spark plug with a sphere-like metal center electrode and manufacturing process thereof
AssigneeNgk Spark Plug Co., Ltd.
InventorsKanemitsu Nishio, Shunichi Takagi, Yasuhiko Suzuki
Life of this patent
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Abstract
A spark plug with a sphere-like center discharge electrode is obtained by pressing a sphere-like metal essentially consisting of noble metal Au, Ag and/or alloys thereof with Pd or the like set on a small end bore formed at a discharge end bottom of a ceramic insulator. Sealing of a sealing material and/or resistor material together with setting (sealing) of a terminal body may be done simultaneously with the pressing of the sphere-like metal on the small end bore by means of hot-pressing applied on the terminal rod head.
Claims25
A spark plug comprising a refractory insulator with a center bore having a bottom end provided with a small end bore being smaller than the remainder of the center bore and a discharge center electrode fixed to said small end bore by means of pressing a metallic sphere having a higher melting point than a sealing temperature of a conductive sealing glass in said small end bore.
A process for manufacturing a spark plug which comprises a step of forming a small end bore at a bottom end of a refractory insulator with a center bore, said small end bore being smaller than the remainder of the center bore, and a step of hot-pressing a metallic sphere, having a higher melting point than a sealing temperature of a conductive sealing glass, in the small end bore outwardly from the center bore thereby forming and making a discharge center electrode tightly fixed to the small end bore.
A process for manufacturing a spark plug which comprises:
- a. forming a small end bore at a bottom end of a refractory insulator with a center bore, said small end bore being smaller than the remainder of the center bore,
- b. setting a metallic sphere on the small end bore on the interior side of the center bore,
- c. charging the center bore with a sealable conductive powder material upon said metallic sphere,
- d. heating the sealable conductive powder material and the metal, and
- e. hot-pressing the sealable conductive powder material and the metal thereby to seal the sealable conductive powder material and the metal thereby to seal the sealable conductive powder material and to form a discharge center electrode.
Dependencies are inferred from the claim text.