Spark plug for a hydrogen internal combustion engine

Abstract

The invention relates to a spark plug (1) for a hydrogen internal combustion engine having a longitudinal axis X, comprising * a housing (2), * an insulator (3) arranged within the housing (2), * a centre electrode (4) arranged within the insulator (3), * a ground electrode (5), * an ignition gap which is formed between the ground electrode (5) and the centre electrode (4) within the housing (2), wherein the housing (2) comprises two opposite bores (20) in which the ground electrode (5) is arranged, and wherein the ground electrode (5) has a recess (50) on one side (51), wherein the ground electrode (5) is arranged such that the recess (50) is axially opposite the centre electrode (4).

Description

[0001] Description

[0002] title

[0003] Spark plug for a hydrogen-powered

[0004] State of the art

[0005] The invention relates to a spark plug.

[0006] The use of hydrogen as a fuel replacement for gasoline has been increasingly promoted for some time. The fuel shift to hydrogen presents new challenges for components in combustion engines, including spark plugs.

[0007] When using a spark plug in a hydrogen environment, undesirable chemical reactions occur between spark plug materials that could be used without problems in a gasoline environment, such as carbon steel. The carbon steel reacts with the hydrogen, resulting in methane formation, which decarbonizes the steel and causes hydrogen corrosion.

[0008] Furthermore, hydrogen is highly reactive and can ignite spontaneously at lower temperatures than gasoline. Therefore, it is necessary to use a spark plug that is as cold as possible.

[0009] The object of the present invention is to provide a spark plug for a hydrogen-powered internal combustion engine that can withstand the demands of the hydrogen environment. Advantage of the invention / Disclosure of the invention

[0010] This task is solved by the spark plug according to the invention

[0011] The spark plug according to the invention is for a hydrogen-powered internal combustion engine and has a longitudinal axis X. The spark plug has:

[0012] • a housing,

[0013] • an insulator arranged inside the housing,

[0014] • a central electrode arranged within the insulator,

[0015] • a ground electrode,

[0016] • an ignition gap formed between the ground electrode and the center electrode within the housing.

[0017] According to the invention, the housing has two opposing bores in which the ground electrode is arranged, so that the ground electrode extends from one inner side of the housing to the opposite inner side of the housing. The ground electrode has a recess on its side, wherein the ground electrode is arranged such that the recess is axially opposite the center electrode. In particular, an axial ignition gap forms between the ground electrode or its recess and the center electrode.

[0018] The spark plug according to the invention has the advantage that the ignition gap is formed within the housing, thus reducing the electrodes' protrusion into the combustion chamber and absorbing less heat from the combustion chamber. Because the ground electrode is located at both ends in the bores of the housing, the ground electrode is thermally well connected to the housing and can effectively dissipate the absorbed heat into the housing. The inventive shape of the ground electrode with the recess offers the advantage that the ignition gap is positioned very precisely within the housing.

[0019] Advantageous further developments of the invention are the subject of the subclaims.

[0020] Advantageously, the ground electrode has a cylindrical shape with rounded end faces, as this allows the ground electrode to be inserted particularly easily into the holes in the housing. For example, at least one hole in the housing is a through-hole, allowing the ground electrode to be pushed from the outside through the through-hole to the opposite hole. The ground electrode is, for example, pressed into the holes and / or welded to the housing.

[0021] In an advantageous further development, an ignition element is arranged in the recess on the side of the ground electrode. In particular, the center electrode also has an ignition element, which, together with the ignition element in the recess of the ground electrode, forms the axial ignition gap.

[0022] It has proven advantageous if the recess on the ground electrode has a width B of at least one diameter of the ignition element, in particular the ignition element diameter + 2 mm. Additionally or alternatively, it is also advantageous if the recess is at least as deep in the axial direction as the ignition element is tall in the axial direction. This allows the ignition element to be easily positioned in the recess.

[0023] In an advantageous embodiment, the ground electrode has a notch on at least one end face that marks the position of the recess on the ground electrode. This makes it easier to align the ground electrode when inserting it so that the recess is aligned with the center electrode.

[0024] drawing

[0025] Figure 1 shows an example of a spark plug with a ground electrode inserted into two holes

[0026] Figure 2 shows an example of inserting the ground electrode into the two holes

[0027] Figure 3 shows the combustion chamber end of the spark plug according to the invention in section

[0028] Description of the exemplary embodiment Figure 1a) shows a spark plug 1. The spark plug 1 has a longitudinal axis X that extends from the end closest to the combustion chamber to the end of the spark plug 1 remote from the combustion chamber. The spark plug 1 has a housing 2 that has a longitudinal bore parallel to the longitudinal axis X of the spark plug 1. On its outer side, the housing 2 typically has a thread 22 with which the spark plug 1 can be screwed into a cylinder head. Typically, an outer seal 7 is arranged on the outer side of the housing 2 and seals a transition between the housing 2 and the cylinder head.

[0029] The insulator s is arranged and secured within the housing 2. Arranged within the insulator 3, starting from its end facing away from the combustion chamber, are a connecting bolt 6, a resistance element, and a center electrode 4, which are electrically connected to one another. The center electrode 4 typically protrudes from the insulator 3 at the combustion chamber end and, in this example, into the interior of the housing 2.

[0030] In this example, the ground electrode 5 is inserted into two holes 20 formed in the housing wall. The holes 20 are, for example, through holes, each extending from the outside to the inside of the housing 2. The ground electrode 5 is rod-shaped, meaning the ground electrode 5 has a cylindrical shape with rounded base surfaces. The ground electrode 5, together with the center electrode 4, forms the axial ignition gap.

[0031] In Figure 1 b), the ground electrode 5 according to the invention is shown separately again for clarity. The ground electrode 5 is rod-shaped with a recess 50 on side 51. An ignition element 55 is arranged in the recess 50. On the end face 52, the rod-shaped ground electrode 5 has a notch 53, which serves to indicate the position of the recess 50 on side 51 of the ground electrode 5 so that the ground electrode 5 can be aligned with the center electrode 4.

[0032] Figure 2 shows how the ground electrode 5 is inserted from the outside through one of the holes 20 (Figure 2a) and pushed through the hole 20 (Figure 2b) until the ground electrode 5 reaches the opposite hole 20 and is inserted therein (Figure 2c). The arrow indicates the direction of movement of the ground electrode 5. The notch 53 on the end face 52 of the ground electrode 5 helps to correctly align the electrode with respect to the center electrode 4. Figure 3 shows the combustion chamber end of the spark plug 1 in a sectioned view.

[0033] Illustration. It can be seen how the ground electrode 5 spans the interior of the housing 2 and thus also the center electrode 4 like a bridge. Accordingly, an axial ignition gap forms between the center electrode 4 and the ground electrode 5. Figure 3 also clearly shows that the ground electrode 5 is inserted into the housing 2 at both ends, thus providing a good thermal connection to the housing 2.

[0034] The recess 50 on the side 51 of the ground electrode 5 has a width B of the diameter of the ignition element 55 plus 2 mm.

Claims

Claims 1 . Spark plug (1) for a hydrogen-powered internal combustion engine with a longitudinal axis X, comprising • a housing (2), • an insulator (3) arranged within the housing (2) • a central electrode (4) arranged within the insulator (3), • a ground electrode (5), • an ignition gap formed between the ground electrode (5) and the center electrode (4) within the housing (2), characterized in that the housing (2) has two opposite bores (20) in which the ground electrode (5) is arranged, and in that the ground electrode (5) has a recess (50) on its side (51), the ground electrode (5) being arranged such that the recess (50) is axially opposite the center electrode (4).

2. Spark plug (1) according to claim 1, characterized in that the ground electrode (5) has a cylindrical shape with round end faces (52).

3. Spark plug (1) according to one of the preceding claims, characterized in that an ignition element (55) is arranged in the recess (50) on the side (51) of the ground electrode (5).

4. Spark plug (1) according to claim 3, characterized in that the recess (51) on the ground electrode (5) has a width B of at least one diameter of the ignition element (55), in particular ignition element diameter + 2 mm.

5. Spark plug (1) according to one of the preceding claims 3 or 4, characterized in that the recess (50) is at least as deep in the axial direction as the ignition element (55) is high in the axial direction.

6. Spark plug (1) according to one of the preceding claims, characterized in that the ground electrode (5) has a notch (53) on at least one end face (52) which indicates the position of the recess (50) on the ground electrode (5).

Images