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US 7,804,232 B2Granted
Spark plug with high durability
AssigneeNgk Spark Plug Co., Ltd.
InventorsKenichi Kumagai, Wataru Matsutani, Kenji Kobayashi
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AssigneeNgk Spark Plug Co., Ltd.
InventorsKenichi Kumagai, Wataru Matsutani, Kenji Kobayashi
Estimating the term…
To provide a spark plug in which separation of a tip can be prevented and enough wear resistance can be obtained without increasing the content of nickel in the tip portion, and a use method of the spark plug. In a spark plug (100) including an outside electrode (10) including an electrode body portion (11) and a tip (12) bonded to the electrode body portion (11), and a center electrode (20), and the tip (12) is opposed to the front end portion of the center electrode (20) through a spark discharge gap (G), the electrode body portion (11) is made of a nickel alloy containing 13 to 18% by mass of Cr, 0.03 to 0.08% by mass of C, 1 to 3.5% by mass of Mo, 0 to 0.8% by mass of Si, Al, Mn and Ti, and 68% by mass or more of Ni, and the tip (12) is made of a platinum alloy containing 0 to 4% by mass of Ni.
A spark plug comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
And Mo or W: with the maximum Cr content being at least 10% but less than 20%
Characterised by features of the electrodes or insulation: selection of materials for electrodes
Alloys
Spark gaps
About 9 months of term left · ends 12 Jul 2027 (estimated)
The present invention relates to a spark plug, and particularly relates to a spark plug showing a high durability.
As a general spark plug, there has been known a spark plug in which a noble metal tip (hereinafter referred to as tip) is welded to a front end of an electrode (center electrode or outside electrode) body so as to extend the life of the spark plug. In such a spark plug, a nickel alloy having nickel as its principal component is typically used for the electrode body. When the tip is simply welded with the electrode body having nickel as its principal component, there is, however, a fear that the tip separates from the electrode body in use so that the durability deteriorates. Therefore, a technique in which nickel is also contained in the tip so as to suppress the separation of the tip is disclosed in the following Patent Document 1. In addition, a technique in which the tip is designed to have a two-layer structure of a low-nickel-content portion and a high-nickel-content portion, and the high-nickel-content portion is welded with an electrode body, is disclosed in the following Patent Document 2.
Patent Document 1: Japanese Patent Laid-Open No. 26480/1983
FIG. 1 An explanatory view showing a section of the vicinity of a tip of an outside electrode in an inventive product (Example 1) with 20-times magnification.
FIG. 2 An explanatory view showing a section of the vicinity of a tip of an outside electrode in a comparative product (Comparative Example 9) with 20-times magnification.
FIG. 3 An explanatory view showing a rectangular region in FIG. 1 (Example 1) with 400-times magnification.
100; spark plug, 10; outside electrode, 11; electrode body portion of outside electrode, 12; outside electrode tip, 20; center electrode, 21; center electrode tip, 221 and 222; conductive glass, 23; resistor; 24; terminal electrode, 30; auxiliary electrode, 40; insulator, 50; metal shell, 51; threaded portion to be attached to internal combustion engine, 52; crimping portion, 611 and 612; sealant, 62; talc, P1; front end surface of center electrode, P2; side surface of center electrode, and P3; half section.
The present invention will be described below in detail.
[1] Spark Plug