JP-2026076366-A - Spark plug electrode precious metal pin, spark plug electrode, spark plug, and method for manufacturing a spark plug electrode

Abstract

[Problem] To provide a spark plug electrode precious metal pin that facilitates manufacturing, reduces costs, and enables a very good balance between spark corrosion characteristics and weldability. [Solution] The spark plug electrode precious metal pin (7) is completely alloyed within the nickel-based electrode substrate (12), and the spark plug electrode precious metal pin (7) is made of an alloy containing -30 to 60 mass% platinum, -40 to 65 mass% nickel, and -0.5 to 5 mass% iridium. [Selection Diagram] Figure 2

Inventors

• ジーフェルト，ポール ユストゥス
• ヴェンク，モーリッツ

Assignees

• ロバート ボッシュ ゲーエムベーハー

Dates

Publication Date

20260511

Application Date

20260219

Priority Date

20220323

Claims (3)

1. A spark plug electrode comprising a spark plug electrode precious metal pin (7), wherein the spark plug electrode precious metal pin (7) is completely alloyed within a nickel-based electrode substrate (12), and the spark plug electrode precious metal pin (7) is -30 to 60 mass% platinum, -40 to 65 mass% nickel and Spark plug electrodes made of an alloy containing -0.5 to 5 mass% iridium.
2. The aforementioned alloy is substantially, -30 to 60 mass% platinum, especially 40 to 50 mass% platinum, -40 to 65 mass% nickel, especially 50 to 60 mass% nickel, A spark plug electrode according to claim 1, comprising -0.5 to 5 mass% iridium, particularly 0.8 to 2 mass% iridium.
3. A spark plug comprising the spark plug electrodes (8, 9) described in claim 1 or 2.

Description

This invention relates to a spark plug electrode noble metal pin for use in generating sparks in a spark plug electrode of an internal combustion engine, and to a spark plug electrode formed together with the spark plug electrode noble metal pin. Furthermore, this invention also relates to a method for manufacturing a spark plug and a spark plug electrode. Spark plug electrodes with precious metal pins, or spark plug electrodes made of precious metals, are known from the prior art. For example, Patent Document 1 teaches a spark plug electrode material characterized by good corrosion resistance and low wear due to spark erosion. The spark plug electrode material contains a first precious metal selected from Pd, Au, Ag, Re, Os, and Ru, Ni in a proportion of 0.5 to 5% by weight relative to the total weight of the spark plug electrode material, and Rh in a proportion of 0.5 to 50% by weight relative to the total weight of the spark plug electrode material. The drawbacks of this spark plug electrode are still excessively high wear overall and the associated high cost. German Patent Application Publication No. 102013210453 In contrast, the present invention provides a spark plug electrode precious metal pin, which is characterized by its extremely high wear resistance and excellent machinability, and can be easily attached to the spark plug electrode base, for example, by welding, without losing its advantageous properties. For this reason, the spark plug electrode precious metal pin according to the present invention is made of an alloy containing more than 80% by mass of platinum, 1 to 10% by mass of nickel, and less than 1 to 10% by mass of iridium, based on the total mass of the spark plug electrode precious metal pin. Platinum and platinum alloys containing iridium are characterized by their low wear rate due to spark corrosion, while platinum and platinum-iridium alloys are also characterized by their high melting points. The drawback of these high-melting-point alloys is their difficult machinability. The above-mentioned elemental amounts for the spark plug electrode precious metal pin according to the present invention refer to the spark plug electrode precious metal pin in an unassembled state, i.e., before bonding with the spark plug electrode substrate. The spark plug electrode precious metal pin is joined to the spark plug electrode base when used as specified. Long-term stable bonding between the spark plug electrode precious metal pin and the spark plug electrode base ensures high operational performance without spark failure (Fehlfunkenbildung). For this purpose, the spark plug electrode precious metal pin needs to be joined to the spark plug electrode base by welding. In this case, another advantage of the composition of the spark plug electrode precious metal pin according to the present invention becomes apparent. Specifically, a nickel content of 1 to 10 mass% relative to the total mass of the spark plug electrode precious metal pin reduces the melting range of the alloy, thereby improving weldability. This applies to all welding methods, but especially to back welding and when the spark plug electrode precious metal pin is completely alloyed within the spark plug electrode base (vollstaendiges Einlegieren). Depending on the welding method used, the composition of the spark plug electrode precious metal pin in the joint region between the spark plug electrode substrate and the spark plug electrode precious metal pin may vary. For example, a weld seam with a mixed composition of the spark plug electrode precious metal pin and the spark plug electrode substrate can be formed. However, in the case of "simple" welds and back welds in which a weld seam is formed, under the specified use of the spark plug electrode precious metal pin, the surface used to generate the ignition spark (hereinafter referred to as the ignition spark surface) still has the composition disclosed above, namely, more than 80% by mass of platinum, 1 to 10% by mass of nickel, and less than 1 to 10% by mass of iridium, respectively, based on the total mass of the spark plug electrode precious metal pin. Nickel is characterized by its high corrosion resistance and lower melting point than platinum and especially iridium. As a result, mixing nickel allows for a reduction in the alloy's melting range while maintaining excellent mechanical properties, which is advantageous for weldability. The dependent claims represent preferred developments of the present invention. According to one advantageous developmental form, the alloy of the spark plug electrode precious metal pin consists substantially of more than 80% by mass of platinum, especially more than 90% by mass of platinum, 1 to 10% by mass of nickel, especially 3 to 7% by mass of nickel, and less than 1 to 10% by mass of iridium, especially 1 to 3% by mass of iridium. There is no need to mix in any more metals, which facilitates the manufacture of the spark plug electrode preci