Spark plug electrode precious metal pin, spark plug electrode, spark plug, and method for manufacturing spark plug electrode

Abstract

The present invention relates to a spark plug electrode precious metal pin (7) made of more than 80 mass % platinum, 1 to 10 mass % nickel, and 1 to less than 10 mass % iridium.

Description

[Technical field]

[0001] The present invention relates to a spark plug electrode precious metal pin for use in spark generation in an internal combustion engine, and a spark plug electrode formed with a spark plug electrode precious metal pin. Additionally, the present invention relates to a spark plug and a method of manufacturing a spark plug electrode. [Background technology]

[0002] Spark plug electrodes with a precious metal pin or made of precious metal are known from the prior art. For example, US Pat. No. 5,999,433 teaches a spark plug electrode material which is 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. A disadvantage of this spark plug electrode is the still too high wear overall and the associated high costs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE 102013210453 Summary of the Invention

[0004] In contrast, the present invention provides a spark plug electrode precious metal pin which is distinguished by very high wear resistance and very good processability and which can be easily attached, for example by welding, to a spark plug electrode base without losing its advantageous properties.

[0005] For this purpose, 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, 1-10% by mass of nickel, and less than 1-10% by mass of iridium, each of which is based on the total mass of the spark plug electrode precious metal pin. Platinum alloys containing platinum and iridium are characterized by a low wear rate due to spark erosion, while platinum and platinum-iridium alloys are also characterized by a high melting point. A disadvantage of these high melting alloys is their difficult workability. The above amounts of elements in the spark plug electrode precious metal pin according to the present invention relate to the spark plug electrode precious metal pin in an unassembled state, i.e. before the formation of a bond with the spark plug electrode base.

[0006] In its intended use, the spark plug electrode pin is joined to the spark plug electrode base. The formation of a long-term stable joint between the spark plug electrode pin and the spark plug electrode base guarantees high operating performance without spark failure. For this purpose, the spark plug electrode pin must be joined to the spark plug electrode base by a welding process. In this case, another advantage of the composition of the spark plug electrode pin according to the invention becomes apparent: a proportion of nickel of 1 to 10% by weight, based on the total weight of the spark plug electrode pin, reduces the melting range of the alloy and thus improves the weldability. This applies to all welding processes, but in particular to back welding and to the complete alloying of the spark plug electrode pin into the spark plug electrode base. The appropriately used welding process can change the composition of the spark plug electrode pin in the joint area between the spark plug electrode base and the spark plug electrode pin. For example, a weld seam can be formed having a mixed composition of the compositions of the spark plug electrode precious metal pin and the spark plug electrode substrate, but in the case of "simple" welds and back welds where the weld seam is formed, in the normal 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, i.e., greater than 80% by weight platinum, 1-10% by weight nickel, and less than 1-10% by weight iridium, each based on the total weight of the spark plug electrode precious metal pin.

[0007] Nickel is characterized by high erosion resistance and a lower melting point than platinum and especially iridium, so that by incorporating nickel it is possible to lower the melting range of the alloy while maintaining excellent mechanical properties, which has an advantageous effect on weldability.

[0008] The dependent claims indicate preferred developments of the invention.

[0009] According to an advantageous development, the alloy of the spark plug electrode precious metal pin consists essentially of more than 80% by weight platinum, in particular more than 90% by weight platinum, 1-10% by weight nickel, in particular 3-7% by weight nickel, and less than 1-10% by weight iridium, in particular 1-3% by weight iridium. No further mixing of metals is necessary, which facilitates the production of the spark plug electrode precious metal pin, saves costs and allows a very good balance between spark erosion properties and weldability.

[0010] Likewise, according to the invention, a first spark plug electrode is also disclosed, which comprises a spark plug electrode precious metal pin made of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel and less than 1-10% by weight of iridium. As already mentioned above, these amounts are in each case relative to the total mass of the spark plug electrode precious metal pin. In addition to this, it is mentioned that, as already mentioned, the use of a welding method to form the joint between the spark plug electrode precious metal pin and the spark plug electrode substrate can result in a different (mixed) composition in the joint area. However, in the prescribed use of the first spark plug electrode, the composition of the spark plug electrode precious metal pin in the area (ignition spark surface) used for generating the ignition spark has in each case an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel and less than 1-10% by weight of iridium. Thus, according to the invention, it is possible to form a spark plug electrode precious metal pin as disclosed above. Due to the use of a specially formulated spark plug electrode precious metal pin, the first spark plug electrode according to the invention is also characterized by low wear due to spark erosion, and therefore high long-term operating performance, especially in modern engines with high power density.In addition, the spark plug electrode, more precisely the spark plug electrode substrate of the spark plug electrode, can be joined to the spark plug electrode precious metal pin very simply and in a long-term durable manner by welding, which prevents spark failure and even complete failure of the spark plug electrode in the intended use.

[0011] In an advantageous embodiment of the first spark plug electrode, the spark plug electrode noble metal pin is joined to the nickel-based electrode substrate by a weld seam, in particular a weld seam formed by back welding. The spark plug electrode noble metal pin thus forms the first spark plug electrode together with the nickel-based electrode substrate to which it is joined by welding, in particular a back welding. The welding results in only a small weld seam between the spark plug electrode noble metal pin and the spark plug electrode substrate, so that the spark plug electrode noble metal pin retains its composition substantially, and in particular in the area used for the generation of the ignition spark (ignition spark surface) in the intended use of the spark plug electrode. The beneficial effect brought about by the spark plug electrode noble metal pin on the first spark plug electrode is thus maintained in the long term.

[0012] According to the invention, a nickel-based electrode substrate is understood to mean a spark plug electrode substrate made of nickel or a nickel alloy, in which case the nickel is more than 50% by weight, in particular more than 80% by weight, based on the total weight of the nickel alloy. Suitable alloying metals are, for example, aluminum, silicon, yttrium, copper, iron, magnesium, manganese, titanium, zirconium and chromium. Nickel alloys that are particularly suitable for use as nickel-based electrode substrates have the following elements: aluminum, silicon, copper and yttrium, less than 5% by weight each, iron and chromium, up to 25% by weight each, and the remainder nickel.

[0013] According to another preferred development, the alloy of the spark plug electrode noble metal pin, at least in the region of the spark plug electrode noble metal pin which is used for the generation of the ignition spark (ignition spark surface) in the intended use of the first spark plug electrode, consists essentially of more than 80% by weight of platinum, in particular more than 90% by weight of platinum, 1-10% by weight of nickel, in particular 3-7% by weight of nickel, and less than 1-10% by weight of iridium, in particular 1-3% by weight of iridium. This allows the formation of a weld seam between the spark plug electrode noble metal pin and the nickel-based electrode body to be facilitated and to be formed stably over the long term. A very low rate of wear due to spark erosion of the spark plug and therefore high operating performance are obtained.

[0014] Further according to the present invention, there is disclosed a second spark plug electrode comprising a spark plug electrode precious metal pin, the spark plug electrode precious metal pin being completely alloyed within a nickel-based electrode substrate, the spark plug electrode precious metal pin being made of an alloy containing 30-60% by weight of platinum, 40-65% by weight of nickel, and 0.5-5% by weight of iridium.

[0015] The second spark plug electrode may also use the spark plug electrode noble metal pin according to the invention disclosed above. However, by completely alloying the spark plug electrode noble metal pin into the nickel-based electrode substrate, the composition of the spark plug electrode noble metal pin in all areas of the pre-placed spark plug electrode noble metal pin is changed. This is due to the composition of the nickel-based electrode substrate containing more than 50% by weight, in particular more than 80% by weight, of nickel (based on the total weight of the nickel-based electrode substrate).

[0016] In other words, the second spark plug electrode can be obtained by using a spark plug electrode noble metal pin made of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel, and less than 1-10% by weight of iridium, and by completely alloying the spark plug electrode noble metal pin into the nickel-based electrode substrate. By using the spark plug electrode noble metal pin, alloying into the nickel-based electrode substrate is also facilitated, and the bond formed between the spark plug electrode noble metal pin and the nickel-based electrode substrate is stable for a long time, and the second spark plug electrode is guaranteed to have a high operating performance for a long time without spark generation failure. Therefore, the second spark plug electrode is also very well protected against wear due to spark erosion.

[0017] Particularly good bond formation between the spark plug electrode noble metal pin and the nickel-based electrode substrate in the second spark plug electrode is obtained if the alloy of the spark plug electrode noble metal pin consists essentially of 30-60% by weight platinum, in particular 40-50% by weight platinum, 40-65% by weight nickel, in particular 50-60% by weight nickel and 0.5-5% by weight iridium, in particular 0.8-2% by weight iridium.

[0018] The present invention further provides a spark plug comprising a first spark plug electrode and / or a second spark plug electrode. The spark plug according to the present invention is characterized by a very good spark erosion behavior and therefore a low wear rate due to spark erosion. Furthermore, spark failures due to spark plug electrode precious metal pins that are not properly machined and bonded to the spark plug electrode substrate are prevented, so that the spark plug has a high long-term operating performance, especially in modern engines with high power density.

[0019] Furthermore, according to the invention, a first method for producing a spark plug electrode is also disclosed, which includes a step of welding, in particular by back welding, a spark plug electrode precious metal pin to a nickel-based electrode substrate. The spark plug electrode precious metal pin used in the welding method consists of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel and less than 1-10% by weight of iridium. Due to the composition of the spark plug electrode precious metal pin, in particular the welding performed by back welding, a homogeneous and therefore long-term stable weld seam is formed between the spark plug electrode precious metal pin and the nickel-based electrode substrate, which prevents displacement and detachment of the spark plug electrode precious metal pin in the long term. By the first method, a spark plug electrode is obtained which is characterized by low wear due to spark erosion and high operating performance, i.e. a first spark plug electrode according to the invention. When a spark plug manufactured by the first method is used as specified, the surface of the spark plug electrode precious metal pin used to generate an ignition spark (ignition spark surface) is made of an alloy containing 80 mass % platinum, 1 to 10 mass % nickel, and 1 to less than 10 mass % iridium.

[0020] According to the present invention, a second method for producing a spark plug electrode is also disclosed, which includes a step of completely alloying the spark plug electrode precious metal pin into the nickel-based electrode substrate. In the second method, the spark plug electrode precious metal pin used is also made of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel, and less than 1-10% by weight of iridium. By completely alloying the spark plug electrode precious metal pin into the nickel-based electrode substrate, the spark plug electrode precious metal pin changes its composition, so that the composition of the spark plug electrode precious metal pin after completion of the spark plug electrode, which exists in the form of a second spark plug electrode, becomes substantially - 30 to 60% by weight of platinum, in particular 40 to 50% by weight of platinum, - 40 to 65% by weight of nickel, in particular 50 to 60% by weight of nickel, - 0.5 to 5% by weight of iridium, in particular 0.8 to 2% by weight of iridium It becomes. The second method also makes it possible to obtain a spark plug electrode which is distinguished by low wear due to spark erosion and very high operating performances, namely the second spark plug electrode according to the invention.

[0021] In order to further simplify the above method by lowering the melting range of the spark plug electrode precious metal pin used in the method, the alloy of the spark plug electrode precious metal pin used for welding consists essentially of more than 80% by weight platinum, in particular more than 90% by weight platinum, 1 to 10% by weight nickel, in particular 3 to 7% by weight nickel, and 1 to less than 10% by weight iridium, in particular 1 to 3% by weight iridium. [Brief description of the drawings]

[0022] [Figure 1] 1 is a partially cutaway view of a spark plug according to a first embodiment. [Diagram 2] FIG. 6 is a schematic partial cross-sectional view of a spark plug according to a second embodiment. [Diagram 3] FIG. 11 is a schematic partial cross-sectional view of a spark plug according to a third embodiment. [Figure 4] FIG. 11 is a schematic partial cross-sectional view of a spark plug according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0024] In the figures, only the essential components of the present invention are shown, and all other components are omitted for clarity, and the same parts / components are provided with the same reference numerals.

[0025] 1, a spark plug 1 according to the present invention comprises a ground electrode 2, a center electrode 3 and an insulator 4. A housing 5 at least partially surrounds the insulator 4. The housing 5 is provided with a thread 6 designed for mounting the spark plug 1 to a cylinder head 10.

[0026] As disclosed above, in particular the ground electrode 2 , and alternatively or additionally the centre electrode 3 , may be formed as a first spark plug electrode 8 or a second spark plug electrode 9 .

[0027] 2 shows a schematic representation of a portion of a first spark plug electrode 8, shown here by way of example as a center electrode. The first spark plug electrode comprises a nickel-based electrode substrate 12 containing more than 50% by weight nickel, based on the total weight of the nickel-based electrode substrate 12. The nickel-based electrode substrate 12 is joined to the spark plug electrode precious metal pin 7 by a weld seam 11.

[0028] In a specified use of the first spark plug electrode 8, the spark plug electrode precious metal pin 7 has an ignition spark surface 13 for generating an ignition spark and is made of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel and less than 1-10% by weight of iridium. In particular, the alloy consists essentially of more than 80% by weight of platinum, in particular more than 90% by weight of platinum, 1-10% by weight of nickel, in particular 3-7% by weight of nickel and less than 1-10% by weight of iridium, in particular 1-3% by weight of iridium.

[0029] The welding of the spark plug electrode noble metal pin 7 to the nickel-based electrode substrate 12 can be carried out by conventional welding methods, whereby the spark plug electrode noble metal pin 7 substantially retains its composition, especially at the ignition spark surface 13. The weld seam 11 is characterized by very good stability and homogeneity, due to the above-mentioned composition of the spark plug electrode noble metal pin 7 containing 1-10 mass % nickel, which reduces the melting range of the spark plug electrode noble metal pin 7 and facilitates welding workability. In addition, the spark plug electrode noble metal pin 7 is characterized by a high wear resistance due to spark erosion due to the high noble metal content, whereby the first spark plug electrode 8 has a high operating performance.

[0030] Fig. 3 shows a schematic partial cross-sectional view of another first spark plug electrode 8, here shown exemplarily as a ground electrode. The first spark plug electrode 8 again comprises a nickel-based electrode body 12, which contains more than 50% by weight of nickel with respect to the total weight of the nickel-based electrode body 12. In contrast to the first spark plug electrode 8 according to Fig. 2, the first spark plug electrode 8 according to Fig. 3 is produced by back welding. This changes the composition of the spark plug electrode noble metal pin 7 in the welded area (see weld seam 11), at least on the surface used to form the joint with the nickel-based electrode body 12, and consists of a mixed alloy of the alloy of the nickel-based electrode body 12 and of the spark plug electrode noble metal pin 7. However, the composition of the spark plug electrode pin 7 in the region of the ignition spark surface 13 remains the composition of the spark plug electrode pin 7 before back welding, i.e. it consists of an alloy containing more than 80% by weight of platinum, 1-10% by weight of nickel and less than 1-10% by weight of iridium. In particular, the alloy essentially consists of more than 80% by weight of platinum, in particular more than 90% by weight of platinum, 1-10% by weight of nickel, in particular 3-7% by weight of nickel and less than 1-10% by weight of iridium, in particular 1-3% by weight of iridium.

[0031] 4 shows a schematic partial cross-sectional view of a second spark plug electrode 9, again shown by way of example as a ground electrode. The second spark plug electrode 9 comprises a nickel-based electrode substrate 12, the nickel-based electrode substrate containing greater than 50% by weight nickel, based on the total weight of the nickel-based electrode substrate 12.

[0032] The spark plug electrode precious metal pin 7 is completely alloyed into the nickel-based electrode substrate 12. Therefore, there are no weld seams.

[0033] The spark plug electrode precious metal pin 7 similarly has an ignition spark surface 13 and is made of an alloy containing 30 to 60 mass % platinum, 40 to 65 mass % nickel, and 0.5 to 5 mass % iridium.

[0034] In particular, the alloy forming the spark plug electrode precious metal pin 7 consists essentially of 30-60% by weight platinum, in particular 40-50% by weight platinum, 40-65% by weight nickel, in particular 50-60% by weight nickel, and 0.5-5% by weight iridium, in particular 0.8-2% by weight iridium.

[0035] By completely alloying the spark plug electrode precious metal pin 7 into the nickel-based electrode substrate 12, a particularly stable bond is formed between the spark plug electrode precious metal pin 7 and the nickel-based electrode substrate 12, which effectively prevents the spark plug electrode precious metal pin 7 from shifting or falling off during long-term, regular use of the second spark plug electrode 9, yet provides a very low wear rate due to spark erosion, thereby providing high long-term operating performance of the second spark plug electrode 9. [Explanation of symbols]

[0036] 1 Spark plug 2 Ground electrode 3 Center electrode 4. Insulation 5. Housing 6 Threads 7 Spark plug electrode precious metal pin 8 First spark plug electrode 9 Second spark plug electrode 10. Cylinder head 11 Welding seam 12 Nickel-based electrode substrate 13 Ignition spark surface

Claims

1. A spark plug electrode precious metal pin, - More than 80% by mass of platinum; -1 to 10% by weight of nickel; -1 to less than 10 mass% iridium A spark plug electrode precious metal pin comprising an alloy containing

2. The alloy is substantially - more than 80% by weight of platinum, in particular more than 90% by weight of platinum, - 1 to 10% by weight of nickel, in particular 3 to 7% by weight of nickel, - 1 to less than 10% by weight of iridium, in particular 1 to 3% by weight of iridium 2. The spark plug electrode precious metal pin of claim 1, comprising:

3. A spark plug electrode, - More than 80% by mass of platinum; -1 to 10% by weight of nickel; -1 to less than 10 mass% iridium A spark plug electrode comprising a spark plug electrode precious metal pin (7) made of an alloy containing

4. 4. The spark plug electrode of claim 3, wherein the spark plug electrode precious metal pin (7) is joined to the nickel-based electrode body (12) by a weld seam (11).

5. The alloy comprises essentially - more than 80% by weight of platinum, in particular more than 90% by weight of platinum, - 1 to 10% by weight of nickel, in particular 3 to 7% by weight of nickel, 5. A spark plug electrode according to claim 3, which consists of from -1 to less than 10% by weight of iridium, in particular from 1 to 3% by weight of iridium.

6. A spark plug electrode comprising a spark plug electrode precious metal pin (7), the spark plug electrode precious metal pin (7) being fully alloyed within a nickel-based electrode substrate (12), the spark plug electrode precious metal pin (7) comprising: -30 to 60% by mass of platinum; - 40 to 65% by weight of nickel; - 0.5 to 5 mass% iridium; A spark plug electrode comprising an alloy containing

7. The alloy comprises essentially - 30 to 60% by weight of platinum, in particular 40 to 50% by weight of platinum, - 40 to 65% by weight of nickel, in particular 50 to 60% by weight of nickel, 0.5 to 5% by weight of iridium, in particular 0.8 to 2% by weight of iridium 7. The spark plug electrode of claim 6, comprising:

8. A spark plug comprising a spark plug electrode (8, 9) according to any one of claims 3 to 7.

9. A method for manufacturing a spark plug electrode (8), comprising the steps of: - More than 80% by mass of platinum; -1 to 10% by weight of nickel; -1 to less than 10 mass% iridium 23. A method comprising the steps of: welding a spark plug electrode precious metal pin (7) comprised of an alloy containing

10. A method for manufacturing a spark plug electrode (9), comprising the steps of: - More than 80% by mass of platinum; -1 to 10% by weight of nickel; -1 to less than 10 mass% iridium The method includes the step of fully alloying a spark plug electrode precious metal pin (7) comprised of an alloy containing nickel into a nickel-based electrode substrate (12).

11. The alloy comprises essentially - more than 80% by weight of platinum, in particular more than 90% by weight of platinum, - 1 to 10% by weight of nickel, in particular 3 to 7% by weight of nickel, - 1 to less than 10% by weight of iridium, in particular 1 to 3% by weight of iridium The method according to claim 9 or 10, comprising:

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