Spark plug for a hydrogen-powered combustion engine

Abstract

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, the housing having two opposite bores in which the ground electrode is arranged.

Description

State of the art

[0001] The invention relates to a spark plug.

[0002] 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 internal combustion engine components, including spark plugs.

[0003] 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. Methane is formed, which decarbonizes the steel, and hydrogen corrosion occurs. The steel becomes brittle and loses its stability.

[0004] 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.

[0005] It is the object of the present invention to provide a spark plug for a hydrogen-powered internal combustion engine that can withstand the requirements of the hydrogen environment. Advantage of the invention / disclosure of the invention

[0006] This problem is solved by the spark plug according to the invention.

[0007] 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: • a housing, • an insulator arranged inside the housing, • a central electrode arranged within the insulator, • a ground electrode, • an ignition gap formed between the ground electrode and the center electrode within the housing.

[0008] 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 bores are formed in the housing wall in the end region of the housing closest to the combustion chamber. In particular, an axial ignition gap is formed between the ground electrode and the center electrode.

[0009] The spark plug according to the invention has the advantage that the ignition gap is formed within the housing, thus reducing the electrodes' penetration 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.

[0010] Advantageous further developments of the invention are the subject of the subclaims.

[0011] It has proven advantageous for the ground electrode to have a cylindrical shape with a rounded base, 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.

[0012] Furthermore, the cylindrical shape of the ground electrode also influences the flow around the ground electrode. Fuel can flow more easily around the cylindrical ground electrode than with a ground electrode with a square cross-section.

[0013] Advantageously, the material used for the ground electrode and / or the center electrode is a material comprising iron, chromium, molybdenum, and nickel. Optionally, the material may also comprise carbon, vanadium, and / or titanium. Preferably, the material for the electrodes contains: - 14% to 23% chromium, - 12% to 28% nickel, - 0.5% to 2.0% molybdenum. - up to 0.2% carbon, - up to 0.2% vanadium, - up to 0.7% titanium and - Iron as residue.

[0014] This material has the advantage of being more resistant to hydrogen corrosion than other materials, so the life of the spark plug is extended.

[0015] With further development, an ignition element containing precious metal on the electrodes can be dispensed with. drawing Fig. 1 shows an example of a spark plug with a ground electrode inserted into two holes Fig. 2 shows an example of inserting the ground electrode into the two holes Fig. 3 shows the combustion chamber end of the spark plug according to the invention in section from a first perspective Fig. 4 shows the combustion chamber end of the spark plug according to the invention in section from a second perspective Description of the embodiment

[0016] Fig. 1 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.

[0017] The insulator 3 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.

[0018] 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 a round base. The ground electrode 5, together with the center electrode 4, forms the axial ignition gap.

[0019] Fig. 2 shows how the ground electrode 5 is inserted from the outside through one of the holes 20 ( Fig. 2a). The ground electrode 5 is pushed through the hole 20 ( Fig. 2b) until the ground electrode 5 reaches the opposite hole 20 and is inserted into it ( Fig. 2c). The arrow indicates the direction of movement of the ground electrode 5.

[0020] Fig. 3 and Fig. 4 show the combustion chamber end of the spark plug 1 in a sectional view from two perspectives offset by 90°. In Fig. 3 shows 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. In Fig. 3 it is also clearly visible that the ground electrode 5 is plugged into the housing 2 at both ends and therefore has a good thermal connection to the housing 2.

[0021] In Fig. 4 shows the flow of the ignited fuel around the ground electrode 5.

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 by that the housing (2) has two opposite bores (20) in which the ground electrode (5) is arranged. [2] Spark plug (1) according to claim 1, characterized by that the ground electrode (5) has a cylindrical shape with round base surfaces. [3] Spark plug (1) according to one of the preceding claims, characterized by that the ground electrode (5) and / or the center electrode (4) has / have no ignition element. [4] Spark plug (1) according to one of the preceding claims, characterized bythat the ground electrode (5) and / or the center electrode (4) consists of a material containing iron, chromium, molybdenum and nickel. [5] Spark plug (1) according to claim 4, characterized by that the material contains 14% to 23% chromium, 12% to 28% nickel, 0.5% to 2.0% molybdenum and iron as the remainder. [6] Spark plug according to claim 4 or 5, characterized by that the material contains carbon up to 0.2%, vanadium up to 0.2% and / or titanium up to 0.7%.

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