Noble metal pin for spark plug electrode, spark plug electrodes, spark plug and method of producing the spark plug electrodes

Abstract

The present invention relates to a noble metal pin (7) for spark plug electrodes, which pin consists of an alloy containing more than 80% by weight platinum, 1 to 10% by weight nickel and 1 to less than 10% by weight iridium.

Description

[0001] Description

[0002] title

[0003] Spark plug electrode precious metal pin, spark plug electrodes, spark plug and method for producing the spark plug electrodes

[0004] State of the art

[0005] The present invention relates to a spark plug electrode precious metal pin for use in spark formation on a spark plug electrode for internal combustion engines, as well as to spark plug electrodes formed with the spark plug electrode precious metal pin. Furthermore, the present invention also relates to a spark plug and methods for producing the spark plug electrodes.

[0006] Spark plug electrodes with precious metal pins or spark plug electrodes made of precious metals are known from the prior art. For example, DE 102013210 453 A1 teaches a spark plug electrode material characterized by good corrosion resistance and low spark erosion wear. 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 wt.%, based on the total weight of the spark plug electrode material, and Rh in a proportion of 0.5 to 50 wt.%, based on the total weight of the spark plug electrode material. The disadvantage of these spark plug electrodes is their overall excessive wear and the associated high costs.

[0007] Disclosure of the invention

[0008] In contrast, the invention provides a spark plug electrode precious metal pin that is characterized by very high wear resistance and very good processability, and can be easily attached to a spark plug electrode base body, for example, by welding, without losing its advantageous properties. For this purpose, the spark plug electrode precious metal pin according to the invention consists of an alloy with more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium, each based on the total mass of the spark plug electrode precious metal pin. While platinum and platinum alloys with iridium are characterized by a low wear rate due to spark erosion, platinum and platinum-iridium alloys are also characterized by high melting points. A disadvantage of these high-melting alloys is their difficult processability.The above quantities of the elements of the spark plug electrode precious metal pin according to the invention refer to the spark plug electrode precious metal pin in the uninstalled state, i.e. before the connection is formed with a spark plug electrode base body.

[0009] When used as intended, the spark plug electrode precious metal pin is connected to a spark plug electrode base body. A permanently stable connection between the spark plug electrode precious metal pin and the spark plug electrode base body ensures high performance without mis-sparking. This requires the spark plug electrode precious metal pin to be connected to the spark plug electrode base body by a welding process. This reveals a further advantage of the composition of the spark plug electrode precious metal pin according to the invention: a nickel content of 1 to 10 mass%, based on the total mass of the spark plug electrode precious metal pin, lowers the melting range of the alloy, thereby improving weldability. This applies to all welding processes, but especially to back-side welding and complete alloying of the spark plug electrode precious metal pin into a spark plug electrode base body.Due to the welding process used, the composition of the spark plug electrode precious metal pin can change in the region of the connection between the spark plug electrode base body and the spark plug electrode precious metal pin. For example, a weld seam can be formed that has a mixed composition of the composition of the spark plug electrode precious metal pin and the spark plug electrode base body. In the case of "simple" welding and back-side welding to form a weld seam, however, the area used for spark generation during intended use of the spark plug electrode precious metal pin (hereinafter referred to as the spark area) still has the following composition, as disclosed above: more than 80 mass% platinum, 1 to 10 mass% nickel, and.

[0010] 1 to less than 10 mass% iridium, each based on the total mass of the spark plug electrode precious metal pin.

[0011] Nickel is characterized by a lower melting point than platinum and especially iridium, while being highly resistant to erosion. By adding it, the melting range of the alloy can be reduced while maintaining its excellent mechanical properties, which has a positive effect on its processability by welding.

[0012] The subclaims show preferred developments of the invention.

[0013] According to an advantageous development, the alloy of the spark plug electrode precious metal pin consists essentially of more than 80 mass% platinum, in particular more than 90 mass% platinum, 1 to 10 mass% nickel, in particular 3 to 7 mass% nickel, and 1 to less than 10 mass% iridium, and among these, in particular, 1 to 3 mass% iridium. Further admixtures of metals are not required, which facilitates the production of the spark plug electrode precious metal pin, saves costs, and enables a very good balance between the spark erosion properties on the one hand and the processability by welding on the other.

[0014] Also disclosed according to the invention is a first spark plug electrode comprising a spark plug electrode precious metal pin made of an alloy containing more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. As already explained above, the amounts relate to the total mass of the spark plug electrode precious metal pin. Furthermore, it is stated that, as already explained, a different (mixed) composition may result in the connection area by using a welding process to form the connection between the spark plug electrode precious metal pin and the spark plug electrode base body.However, the composition of the spark plug electrode precious metal pin in the area that serves to generate the ignition spark during intended use of the first spark plug electrode (spark area) always comprises an alloy with more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. The spark plug electrode precious metal pin can therefore be designed as disclosed above according to the invention. Due to the use of the specifically composed spark plug electrode precious metal pin, the first spark plug electrode according to the invention is also characterized by low spark erosion wear and thus by a permanently high mileage, particularly in modern engines with high power density.In addition, the spark plug electrode, or more precisely a spark plug electrode base body of the spark plug electrode, can be very easily and permanently connected to the spark plug electrode precious metal pin by welding, which prevents misfires and even a complete failure of the spark plug electrode when used as intended.

[0015] In an advantageous embodiment of the first spark plug electrode, the spark plug electrode precious metal pin is connected to a nickel base electrode body by a weld seam, and in particular by a weld seam formed by back-side welding. The spark plug electrode precious metal pin thus forms the first spark plug electrode together with the nickel base electrode body, to which it is connected by welding, and in particular by back-side welding. The welding creates only a small weld seam between the spark plug electrode precious metal pin and the spark plug electrode body, so that the spark plug electrode precious metal pin essentially retains its composition, particularly in the area that serves to generate the ignition spark (ignition spark area) during intended use of the spark plug electrode.This means that the beneficial effects introduced into the first spark plug electrode by the spark plug electrode precious metal pin are permanently maintained.

[0016] According to the invention, a nickel base electrode base body is understood to be a spark plug electrode base body made of nickel or a nickel alloy, wherein, in the case of a nickel alloy, nickel accounts for more than 50 mass% and in particular more than 80 mass%, based on the total mass of the nickel alloy. Suitable alloying metals include, for example, aluminum, silicon, yttrium, copper, iron, magnesium, manganese, titanium, zirconium, and chromium. A particularly suitable nickel alloy for use as a nickel base electrode base body comprises the following elements: aluminum, silicon, copper, and yttrium, each with less than 5 mass%, and iron and chromium, each with up to 25 mass%, with the remainder being nickel.

[0017] According to a further preferred development, the alloy of the spark plug electrode precious metal pin, at least in the area of ​​the spark plug electrode precious metal pin that serves to generate the ignition spark when the first spark plug electrode is used as intended (ignition spark area), consists essentially of more than 80 mass% platinum, in particular more than 90 mass% platinum, 1 to 10 mass% nickel, in particular 3 to 7 mass% nickel, and 1 to less than 10 mass% iridium, and in particular 1 to 3 mass% iridium. This facilitates the formation of the weld seam between the spark plug electrode precious metal pin and the nickel base electrode body and ensures lasting stability. A very low spark erosion wear rate and thus a high service life of the spark plug are also achieved.

[0018] Furthermore, the invention also discloses a second spark plug electrode which comprises a spark plug electrode precious metal pin, wherein the spark plug electrode precious metal pin is completely alloyed into a nickel base electrode body, and wherein the spark plug electrode precious metal pin consists of an alloy with 30 to 60 mass% platinum, 40 to 65 mass% nickel and 0.5 to 5 mass% iridium.

[0019] The above-disclosed inventive spark plug electrode precious metal pin can also be used for the second spark plug electrode. However, due to the complete alloying of the spark plug electrode precious metal pin into the nickel base electrode body, the composition of the spark plug electrode precious metal pin changes in all areas of the previously arranged spark plug electrode precious metal pin. This is due to the composition of the nickel base electrode body, which comprises more than 50 mass% and in particular more than 80 mass% nickel (based on the total mass of the nickel base electrode body).In other words, the second spark plug electrode can be obtained by using a spark plug electrode precious metal pin made of an alloy containing more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium, and by completely alloying the spark plug electrode precious metal pin into a nickel base electrode body. The use of the spark plug electrode precious metal pin also facilitates alloying into the nickel base electrode body, and the resulting bond between the spark plug electrode precious metal pin and the nickel base electrode body is permanently stable, ensuring consistently high service life of the second spark plug electrode without misfires. This also provides excellent protection against spark erosion wear for the second spark plug electrode.

[0020] A particularly good connection formation between the spark plug electrode precious metal pin and the nickel base electrode body in the second spark plug electrode is obtained when the alloy of the spark plug electrode precious metal pin consists essentially of 30 to 60 mass% platinum, in particular 40 to 50 mass% platinum, 40 to 65 mass% nickel, in particular 50 to 60 mass% nickel and 0.5 to 5 mass% iridium and in particular 0.8 to 2 mass% iridium.

[0021] Furthermore, the invention also describes a spark plug comprising the first spark plug electrode and / or the second spark plug electrode. The spark plug according to the invention is characterized by very good spark erosion behavior and thus by a low wear rate due to spark erosion. Furthermore, incorrect sparking caused by improperly processed precious metal spark plug electrode pins connected to a spark plug electrode base body is prevented, so that the spark plug has a consistently high service life, particularly in modern engines with high power density.

[0022] Furthermore, the invention also discloses a first method for producing a spark plug electrode, which comprises a step of welding, in particular back-welding, a spark plug electrode precious metal pin to a nickel base electrode body. The spark plug electrode precious metal pin used for the welding process consists of an alloy with more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. Due to the composition of the spark plug electrode precious metal pin, the welding, which is carried out in particular by back-welding, forms a homogeneous and thus permanently stable weld seam between the spark plug electrode precious metal pin and the nickel base electrode body, so that slipping or breakage of the spark plug electrode precious metal pin is permanently prevented.The first method produces a spark plug electrode, namely a first spark plug electrode according to the invention, which is characterized by high mileage with low spark erosion wear. The surface of the precious metal spark plug electrode pin used for spark generation during intended use of the spark plug produced by the first method consists of an alloy containing more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium.

[0023] According to the invention, a second method for producing a spark plug electrode is also disclosed, which comprises a step of completely alloying a spark plug electrode precious metal pin into a nickel base electrode body. In the second method, the spark plug electrode precious metal pin used also consists of an alloy containing more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. By completely alloying the spark plug electrode precious metal pin into the nickel base electrode body, 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 is in the form of a second spark plug electrode, is essentially as follows:

[0024] 30 to 60 mass% platinum, in particular 40 to 50 mass% platinum, 40 to 65 mass% nickel, in particular 50 to 60 mass% nickel and 0.5 to 5 mass% iridium, in particular 0.8 to 2 mass% iridium.

[0025] The second method also produces a spark plug electrode, namely a second spark plug electrode according to the invention, which is characterized by very high service life with low spark erosion wear. To further simplify the above methods by lowering the melting range of the spark plug electrode precious metal pin used for the method, the alloy of the spark plug electrode precious metal pin used for welding consists essentially of more than 80 mass% platinum, in particular more than 90 mass% platinum, 1 to 10 mass% nickel, in particular 3 to 7 mass% nickel, and 1 to less than 10 mass% iridium, and in particular 1 to 3 mass% iridium.

[0026] Short description of the drawing

[0027] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0028] Figure 1 is a partially sectioned view of a spark plug according to a first embodiment,

[0029] Figure 2 is a schematic partial section of a spark plug according to a second embodiment in section,

[0030] Figure 3 is a schematic partial section of a spark plug according to a third embodiment in section and

[0031] Figure 4 is a schematic partial section of a spark plug according to a fourth embodiment in section.

[0032] Embodiments of the invention

[0033] The figures show only the essential components of the present invention; all other components have been omitted for clarity. Furthermore, identical reference numerals refer to identical parts / components.

[0034] As can be seen from Figure 1, the spark plug 1 according to the invention comprises a ground electrode 2, a center electrode 3, and an insulator 4. A housing 5 at least partially surrounds the insulator 4. A thread 6 is arranged on the housing 5, which is designed for fastening the spark plug 1 in a cylinder head 10. In particular, the ground electrode 2, but alternatively or additionally also the center electrode 3, can be designed as a first spark plug electrode 8 or as a second spark plug electrode 9, as disclosed above.

[0035] Figure 2 schematically shows a section of a first spark plug electrode 8, which is shown here as an example as a center electrode. It comprises a spark plug electrode base body, which is a nickel base electrode base body 12 and comprises nickel with more than 50 mass%, based on the total mass of the nickel base electrode base body 12. The nickel base electrode base body 12 is connected to a spark plug electrode precious metal pin 7 by a weld seam 11.

[0036] The spark plug electrode precious metal pin 7 has an ignition spark surface 13 that serves to generate the ignition spark when the first spark plug electrode 8 is used as intended and consists of an alloy containing more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. Preferably, the alloy consists essentially of more than 80 mass% platinum, in particular more than 90 mass% platinum, 1 to 10 mass% nickel, in particular 3 to 7 mass% nickel, and 1 to less than 10 mass% iridium, and in particular 1 to 3 mass% iridium.

[0037] Welding of the spark plug electrode precious metal pin 7 to the nickel base electrode body 12 can be carried out using a conventional welding process, whereby the spark plug electrode precious metal pin 7 essentially retains its composition, particularly at the ignition spark surface 13. The weld seam 11 is characterized by very good stability and homogeneity, which is attributable to the fact that the above-mentioned composition of the spark plug electrode precious metal pin 7 comprises nickel at 1 to 10 mass%, thereby reducing the melting range of the spark plug electrode precious metal pin 7 and facilitating processability by welding. Furthermore, due to the high precious metal content, the spark plug electrode precious metal pin 7 is characterized by high spark erosion wear, so that the first spark plug electrode 8 has a long service life.Figure 3 shows a schematic section of a further first spark plug electrode 8, which is shown here as an example as a ground electrode. The first spark plug electrode 8 comprises a spark plug electrode base body, which in turn is a nickel base electrode base body 12 and comprises nickel with more than 50 mass%, based on the total mass of the nickel base electrode base body 12. In contrast to the first spark plug electrode 8 from Figure 2, the first spark plug electrode 8 from Figure 3 is produced by back-side welding. This results in the composition of the spark plug electrode precious metal pin 7 changing in the welded area (see weld seam 11), at least on the surface that serves to form the connection with the nickel base electrode base body 12, and consisting of a mixed alloy of the alloy of the nickel base electrode base body 12 and the alloy of the spark plug electrode precious metal pin 7.However, the composition of the spark plug electrode precious metal pin 7 in the region of the ignition spark surface 13 still has the composition of the spark plug electrode precious metal pin 7 as before the back-side welding, namely, it consists of an alloy with more than 80 mass% platinum, 1 to 10 mass% nickel, and 1 to less than 10 mass% iridium. Preferably, the alloy consists essentially of more than 80 mass% platinum, in particular more than 90 mass% platinum, 1 to 10 mass% nickel, in particular 3 to 7 mass% nickel, and 1 to less than 10 mass% iridium, and in particular 1 to 3 mass% iridium.

[0038] Figure 4 shows a schematic section of a second spark plug electrode 9, which is also shown here as a ground electrode by way of example. The second spark plug electrode 9 comprises a spark plug electrode base body, which is a nickel base electrode base body 12 and comprises nickel with more than 50 mass%, based on the total mass of the nickel base electrode base body 12.

[0039] A spark plug electrode precious metal pin 7 is fully alloyed into the nickel base electrode body 12. Thus, there is no weld seam. The spark plug electrode precious metal pin 7 also has an ignition spark surface 13 and consists of an alloy containing 30 to 60 mass% platinum, 40 to 65 mass% nickel, and 0.5 to 5 mass% iridium.

[0040] In particular, the alloy forming the spark plug electrode precious metal pin 7 consists essentially of 30 to 60 mass% platinum, in particular 40 to 50 mass% platinum, 40 to 65 mass% nickel, in particular 50 to 60 mass% nickel and 0.5 to 5 mass% iridium, in particular 0.8 to 2 mass% iridium.

[0041] By completely alloying the spark plug electrode precious metal pin 7 into the nickel base electrode body 12, a particularly stable connection is formed between the spark plug electrode precious metal pin 7 and the nickel base electrode body 12, so that slipping or falling out of the spark plug electrode precious metal pin 7 is effectively prevented even during continuous, intended use of the second spark plug electrode 9 and yet very low spark erosion wear rates are maintained, so that the service life of the second spark plug electrode 9 is permanently high.

Claims

Claims 1. Spark plug electrode precious metal pin consisting of an alloy with: more than 80% platinum by mass, 1 to 10% by mass nickel and 1 to less than 10% iridium by mass.

2. Spark plug electrode precious metal pin according to claim 1, wherein the alloy essentially consists of: more than 80% platinum by mass, in particular more than 90% platinum by mass, 1 to 10% by mass nickel, in particular 3 to 7% by mass nickel and 1 to less than 10 mass% iridium, in particular 1 to 3 mass% iridium.

3. Spark plug electrode comprising a spark plug electrode precious metal pin (7) consisting of an alloy with: more than 80 wt% platinum, 1 to 10% by mass nickel and 1 to less than 10% iridium by mass.

4. Spark plug electrode according to claim 3, wherein the spark plug electrode precious metal pin (7) is connected to a nickel-based electrode base body (12) by a weld (11).

5. Spark plug electrode according to claim 3 or 4, wherein the alloy essentially consists of: more than 80% platinum by mass, in particular more than 90% platinum by mass, 1 to 10% by mass nickel, in particular 3 to 7% by mass nickel and 1 to less than 10% iridium by mass, in particular 1 to 3% iridium by mass consists of 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 in a nickel-based electrode body (12), wherein the spark plug electrode precious metal pin (7) is made of an alloy with: 30 to 60% platinum by mass, 40 to 65% by mass nickel and 0.5 to 5 wt% iridium. Spark plug electrode according to claim 6, wherein the alloy essentially consists of: 30 to 60% platinum by mass, especially 40 to 50% platinum by mass, 40 to 65 wt% nickel, in particular 50 to 60 wt% nickel, and 0.5 to 5 wt% iridium, in particular 0.8 to 2 wt% iridium. Spark plug comprising a spark plug electrode (8, 9) according to any one of claims 3 to 7. Method for manufacturing a spark plug electrode (8) comprising a step of welding a spark plug electrode precious metal pin (7) consisting of an alloy with: more than 80 wt% platinum 1 to 10% by mass nickel and 1 to less than 10 wt% iridium on a nickel-based electrode core (12). Method for manufacturing a spark plug electrode (9) comprising a step of completely alloying a spark plug electrode precious metal pin (7) consisting of an alloy with: more than 80 wt% platinum 1 to 10% by mass nickel and 1 to less than 10 mass% iridium in a nickel-based electrode body (12). A method according to claim 9 or 10, wherein the alloy consists essentially of: more than 80% platinum by mass, in particular more than 90% platinum by mass, - 1 to 10% nickel by mass, in particular 3 to 7% nickel by mass and 1 to less than 10 mass% iridium, in particular 1 to 3 mass% iridium.

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