Method for manufacturing a spark plug electrode system and a spark plug, spark plug electrode system, and spark plug

Abstract

A method for manufacturing a spark plug electrode system including a ground electrode and a center electrode, which are connected to each other by a joining area, formed from a one-piece spark plug electrode base body made up of spark plug electrode material.

Claims

1. A method for manufacturing a spark plug electrode system including a ground electrode and a center electrode, which are connected to each other by a joining area, the method comprising: forming the ground electrode, the center electrode, and the joining area together from a one-piece spark plug electrode base body made up of spark plug electrode material; wherein the spark plug electrode material is a nickel-chromium alloy or a nickel-yttrium alloy.

2. The method as recited in claim 1, wherein the formation of the ground electrode, the center electrode, and the joining area includes removing spark plug electrode material from the spark plug electrode base body.

3. The method as recited in claim 2, further comprising: forming an ignition spark gap between the ground electrode and the center electrode by removing spark plug electrode material from the spark plug electrode base body, the ground electrode and the center electrode remaining connected to each other by the joining area made up of the spark plug electrode material.

4. The method as recited in claim 2, wherein the removal of the spark plug electrode material from the spark plug electrode base body is carried out via punching or material removal or eroding or lasering.

5. The method as recited in claim 1, further comprising: deep drawing at least one area of the spark plug electrode base body.

6. The method as recited in claim 1, further comprising: building up spark plug electrode material in such a way that the ground electrode, the center electrode, and the joining area connecting the ground electrode and the center electrode, are formed as one piece.

7. The method as recited in claim 6, wherein the build-up of spark plug electrode material takes place in such a way that an ignition spark gap is formed between the ground electrode and the center electrode, the ground electrode and the center electrode remaining connected to each other by the joining area made up of the spark plug electrode material.

8. The method as recited in claim 6, wherein the build-up of the spark plug electrode material is carried out by 3D printing.

9. The method as recited in claim 1, wherein the ground electrode encompasses the center electrode at least in sections.

10. The method as recited in claim 1, wherein the joining area is in the form of at least one web, which connects the ground electrode and the center electrode to each other.

11. The method as recited in claim 10, wherein the joining area includes two to four webs, which connect the ground electrode and the center electrode to each other.

12. The method as recited in claim 1, further comprising: situating at least one first noble metal at the ground electrode and/or at least one second noble metal at the center electrode, the first noble metal and/or the second noble metal being situated in such a way that they are situated in an area forming a spark gap between the ground electrode and the center electrode.

13. The method as recited in claim 1, further comprising: providing openings in the ground electrode and/or in the center electrode.

14. The method as recited in claim 1, wherein the ground electrode is a cylindrical ring, the center electrode is a cylinder, and the joining area includes a plurality of webs which each connect the ground electrode to the center electrode, the plurality of webs being separated from one another by free areas which are free from all materials.

15. A method for manufacturing a spark plug including a spark plug electrode system including a ground electrode and a center electrode, which are connected to each other by a joining area, formed from a one-piece spark plug electrode base body made up of spark plug electrode material, the method comprising: connecting the spark plug electrode system to a spark plug base body; wherein the spark plug electrode material is a nickel-chromium alloy or a nickel-yttrium alloy.

16. The method as recited in claim 15, wherein the ground electrode is connected to a housing of the spark plug and/or the center electrode is connected to an electrical terminal for the center electrode.

17. The method as recited in claim 15, wherein the connection is carried out using laser welding, or using resistance welding, or using brazing.

18. The method as recited in 15, further comprising: removing the joining area between the ground electrode and the center electrode.

19. The method as recited claim 15, further comprising: providing openings in the ground electrode and/or in the center electrode.

20. The method as recited in claim 15, wherein the ground electrode is a cylindrical ring, the center electrode is a cylinder, and the joining area includes a plurality of webs which each connect the ground electrode to the center electrode, the plurality of webs being separated from one another by free areas which are free from all materials.

21. The method as recited in claim 20, further comprising: after connecting the spark plug electrode system to the spark plug base body, removing the joining area including the plurality of webs between the ground electrode and the center electrode.

22. A spark plug electrode system, comprising: a ground electrode and a center electrode connected to each other by a joining area, the spark plug electrode system being formed as one piece from a spark plug electrode material; wherein the spark plug electrode material is a nickel-chromium alloy or a nickel-yttrium alloy.

23. The spark plug electrode system as recited in claim 22, wherein the center electrode is cylindrically designed and/or the ground electrode is designed in the form of a cylindrical ring and/or the joining area is formed from at least one web.

24. The spark plug electrode system as recited in claim 22, wherein the ground electrode is a cylindrical ring, the center electrode is a cylinder, and the joining area includes a plurality of webs which each connect the ground electrode to the center electrode, the plurality of webs being separated from one another by free areas which are free from all materials.

25. The spark plug electrode system as recited in claim 24, wherein areas for the ground electrode between the webs include a first noble metal, areas of the center electrode between the webs include a second noble metal, and the webs are free of the first noble metal and the second noble metal.

26. A spark plug, comprising: a spark plug electrode system including a ground electrode and a center electrode, which are connected to each other by a joining area, formed from a one-piece spark plug electrode base body made up of spark plug electrode material; and a spark plug base body to which the spark plug electrode system is connected; wherein the spark plug electrode material is a nickel-chromium alloy or a nickel-yttrium alloy.

27. A spark plug, comprising: a ground electrode and a center electrode, which, between each other, define a spark gap, the ground electrode encompassing the center electrode, wherein the ground electrode and the center electrode are formed from a one-piece spark plug electrode base body made up of spark plug electrode material, and wherein the spark plug electrode material is a nickel-chromium alloy or a nickel-yttrium alloy; wherein: (i) a first noble metal is situated at the ground electrode, in an area forming the spark gap between the ground electrode and the center electrode, and the first noble metal includes at least one section, which is free of the first noble metal, and/or (ii) a second noble metal is situated at the center electrode, in the area forming the spark gap between the ground electrode and the center electrode, and the second noble metal includes at least one section, which is free of the second noble metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are described in detail below with reference to the figures.

(2) FIG. 1 shows a partial sectional view of a spark plug according to a first specific embodiment of the present invention.

(3) FIG. 2 shows a cut view of a spark plug according to a second specific embodiment of the present invention.

(4) FIG. 3 shows a cross section of a spark plug electrode system according to a third specific embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(5) Only the details of main features of the present invention are represented in the figures. All other details have been omitted for the sake of clarity. In addition, identical reference numerals relate to identical components.

(6) As is shown in FIG. 1, spark plug 1 encompasses a ground electrode 2, a center electrode 3, and an insulator 4. A housing 5 at least partially encompasses insulator 4. A thread 6, which is designed for fastening spark plug 1 in a cylinder head 7, is situated at housing 5. Center electrode 3 is connected to an electrical terminal 8 in order to generate an ignition spark.

(7) In spark plug 1 from FIG. 1, ground electrode 2 and center electrode 3 are formed from the same material, namely in such a way that ground electrode 2 and center electrode 3, initially connected to each other by a joining area, are formed from a one-piece spark plug electrode base body made up of spark plug electrode material, for example, by deep drawing the spark plug electrode base body.

(8) A first noble metal 12 is then situated on ground electrode 2 and a second noble metal 13 is situated on center electrode 3, a spark gap F being formed between first noble metal 12 and second noble metal 13.

(9) In one further step, the spark plug electrode base body is connected to a spark plug base body 9, which, as shown here, includes housing 5, insulator 4, and electrical terminal 8.

(10) As shown here, ground electrode 2 is connected to housing 5 preferably by a first welded joint S1 and center electrode 3 is advantageously connected to electrical terminal 8 by a second welded joint S2. The joining area, which was initially formed between ground electrode 2 and center electrode 3, has been removed in order to start up spark plug 1.

(11) Due to the fact that ground electrode 2 and center electrode 3 as well as noble metals 12, 13 respectively situated thereon are manufactured in that a joining area is formed between ground electrode 2 and center electrode 3, the electrode spacing between first noble metal 12 of ground electrode 2 and second noble metal 13 of center electrode 3 in spark plug 1 represented in FIG. 1 is permanently stable and highly precisely set to a predetermined distance. Consequently, spark plug 1 is distinguished by a high power density and a low spark-erosive wear.

(12) FIG. 2 shows a partial section of a spark plug 1 according to a second specific embodiment. Ground electrode 2 is designed in the form of a roof electrode and projects over center electrode 3. At the combustion chamber-side end of center electrode 3, center electrode 3 includes a second noble metal 13, which is designed in the form of a box-shaped or cylindrical small plate. Diametrically opposed thereto, a first noble metal 12, likewise in the form of a box-shaped or cylindrical small plate, is situated at ground electrode 2. Spark gap F is formed between first noble metal 12 and second noble metal 13. The ignition spark is generated here. First noble metal 12 includes a noble metal-free section 14 and second noble metal 13 includes a noble metal-free section 20.

(13) Noble metal-free sections 14, 20 result from the manufacture of spark plug 1. For the manufacture of spark plug 1 according to the second specific embodiment, a spark plug electrode system, which includes a ground electrode 2, a center electrode 3, and a joining area 11, designed as one piece, is connected to a spark plug base body. The spark plug electrode system is formed from a one-piece spark plug electrode base body made up of spark plug electrode material. Joining area 11 is indicated by dashed lines in FIG. 2.

(14) A spark plug electrode base body 15 to be utilized for this purpose may be designed to be, for example, box-shaped or fully cylindrical. One possible contour of a spark plug electrode base body 15 of this type is represented in FIG. 2 by dashed lines. The spark plug electrode material preferably includes nickel as the main element and is made up, in particular, of a nickel-chromium alloy or a nickel-yttrium alloy.

(15) Ground electrode 2, center electrode 3, and a joining area 11 connecting ground electrode 2 and center electrode 3 may be formed from spark plug electrode base body 15, for example, by removing spark plug electrode material. The removal of spark plug electrode material may be carried out particularly well with the aid of a material-removing process, via eroding, via treatment with the aid of a laser, or by punching. In addition, as a result, spark gap F as well as further free areas 16 may be formed between ground electrode 2 and center electrode 3. Joining area 11 is formed between the combustion chamber-side end of center electrode 3 and the area of ground electrode 2 diametrically opposed to the combustion chamber-side end of center electrode 3.

(16) Ground electrode 2, center electrode 3, and joining area 11 are therefore formed as one piece from the same material. In one further method step, first noble metal 12 is applied onto ground electrode 2 and second noble metal 13 is applied onto center electrode 3, so that first noble metal 12 and second noble metal 13 are positioned opposite one another in the area of the spark gap. Joining area 11 between ground electrode 2 and center electrode 3 is only removed in a step downstream from this method step. As a result, a noble metal-free section 20 remains at center electrode 3 and a noble metal-free section 14 remains at ground electrode 2. Noble metal-free sections 14, 20 may contain spark plug electrode material, provided that the spark plug electrode material of the former joining area has not also been removed in these areas.

(17) FIG. 3 shows a spark plug electrode system 10 according to a third specific embodiment of the present invention. Spark plug electrode system 10 includes a center electrode 3, which is encompassed by a ground electrode 2 in the manner of a cylindrical ring. Center electrode 3 and ground electrode 2 are connected to each other by a joining area 11. Spark plug electrode system 10 is manufactured from a one-piece spark plug electrode base body, so that ground electrode 2, center electrode 3, and joining area 11 are also formed as one piece in spark plug electrode system 10, i.e., also from the same material without ledges or joining seams.

(18) One exemplary method for manufacturing ground electrode 2, center electrode 3, and joining area 11 includes a step of removing spark plug electrode material from the spark plug electrode base body. In the specific embodiment shown in FIG. 3, the spark plug electrode base body may have, for example, a fully cylindrical shape having a diameter A. Diameter A is preferably maximally as great as the inner diameter of the housing of the spark plug, in which spark plug electrode system 10 is to be installed, so that an accurate fastening of spark plug electrode system 10 is easily possible.

(19) By removing spark plug electrode material, four free areas 16 result, which are to be allocated to spark gap F.

(20) Alternatively to the above-described method, ground electrode 2, center electrode 3, and joining area 11 may also be formed as one piece by building up spark plug electrode material, for example, by utilizing a 3D printing method.

(21) In the present specific embodiment, joining area 11 is made up of four webs 11a, which are situated at a 90° angle with respect to one another.

(22) A first noble metal 12 is situated on inner surface 17 of ground electrode 2 facing center electrode 3. A second noble metal 13 is situated on outer surface 18 of center electrode 3 facing ground electrode 2. First noble metal 12 and second noble metal 13 are not situated in joining area 11.

(23) Spark gap F results between first noble metal 12 and second noble metal 13.

(24) In order to manufacture a spark plug by utilizing spark plug electrode system 10 shown here, joining area 11 made up of four webs 11a is removed. For example, sections 19 of the webs may be removed, so that ground electrode 2 and center electrode 3 are no longer electrically connected to each other. Sections 19 are situated between first noble metal 12 and second noble metal 13 in open area 16. By removing sections 19, sections 14 remain at ground electrode 2, which are noble metal-free but contain spark plug electrode material and sections 20 remain at center electrode 3, which are noble metal-free but contain spark plug electrode material. These therefore extend through first noble metal 12 and second noble metal 13.

(25) Preferably, the removal of joining area 11 takes place in such a way that joining area 11 situated between first noble metal 12 and second noble metal 13 is also at least partially removed. Therefore, a section 21 is removed, as represented in FIG. 3. This results in the formation of open areas between first noble metal 12 on the one side and second noble metal 13 on the other side and, moreover, to exposed corners 22 of first noble metal 12 and exposed corners 23 of second noble metal 13, at which field enhancements in the electric field are present, so that the ignition voltage demand for the ignition spark formation may be reduced.

(26) After the removal of joining area 11, center electrode 3 has a fully cylindrical shape and ground electrode 2 has the shape of a cylindrical ring.

(27) By providing joining area 11 and the one-piece design of ground electrode 2, center electrode 3, and joining area 11, a fixed and precisely predeterminable electrode spacing results, due to the geometric configuration of spark plug electrode system 10, from which a precisely formed spark gap F also results after the application of first noble metal 12 and second noble metal 13. A spark plug manufactured by utilizing spark plug electrode system 10 according to the present invention is distinguished by a high power density and a low spark-erosive wear.