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 (2), wherein the housing (2) has two opposite bores (20) in which the ground electrode (5) is arranged, and that the ground electrode (5) has a recess (50) on its side (51), wherein the ground electrode (5) is arranged such that the recess (50) is axially opposite the center electrode (4).

Description

Prior ArtThe present invention relates to a spark plug.Recently, the use of hydrogen as a gasoline fuel substitute has been increasingly advanced. With the change of fuel to hydrogen, new challenges arise for the components in the internal combustion engine, and also for the spark plug.When the spark plug is used in a hydrogen environment, undesirable chemical reactions occur between the spark plug materials which could be used without problems in a gasoline environment, such as the carbon steel. The carbon steel reacts with the hydrogen. Methane formation occurs, as a result of which the steel is decarbonized and hydrogen corrosion occurs.Furthermore, hydrogen is very reactive and can self-ignite at lower temperatures than gasoline. It is therefore necessary to use a spark plug which is as cold as possible.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 in the hydrogen environment.Advantage of the invention / disclosure of the inventionThis object is achieved by the spark plug according to the invention.The spark plug according to the invention is for a hydrogen-operated internal combustion engine and has a longitudinal axis X. The spark plug has:• a housing,• an insulator arranged inside the housing,• a center electrode arranged inside the insulator,• a ground electrode,• a spark gap formed between the ground electrode and the center electrode inside the housing.According to the invention, the housing has two opposing bores in which the ground electrode is arranged, so that the ground electrode extends from an inner side of the housing to the opposing inner side of the housing. The ground electrode has a recess on its side, the ground electrode being arranged such that the recess is axially opposite to the center electrode. In particular, an axial ignition gap is formed between the ground electrode or the depression thereof and the center electrode.The spark plug according to the invention has the advantage that the spark gap is formed within the housing and therefore the electrodes do not protrude as far into the combustion chamber and thus absorb less heat from the combustion chamber. Because the ground electrode is arranged at both of its ends in the bores of the housing, the ground electrode is thermally well connected to the housing and can well dissipate the absorbed heat into the housing. The shape according to the invention of the ground electrode with the depression results in the advantage that the ignition gap is arranged within the housing in a very defined manner.Advantageous further developments of the invention are the subject matter of the dependent claims.Advantageously, the ground electrode has a cylindrical shape with round end faces, since the ground electrode can then be inserted particularly easily into the bores in the housing. For example, at least one bore in the housing is a through bore, so that the ground electrode can be pushed from the outside through the through bore as far as the opposite bore. The ground electrode is, for example, pressed into the bores and / or welded to the housing.In an advantageous development, an ignition element is arranged in the depression on the side of the ground electrode. In particular, the center electrode also has an ignition element which, together with the ignition element, forms the axial ignition gap in the depression of the ground electrode.It has proven to be advantageous if the depression on the ground electrode has a width B of at least one diameter of the ignition element, in particular ignition element diameter+2 mm. Additionally or alternatively, it is also advantageous if the depression is as deep at least in the axial direction as the ignition element is high in the axial direction. Since the ignition element can then be arranged well in the depression.In an advantageous embodiment, the ground electrode has a notch on at least one end face, which notch marks the position of the depression on the ground electrode. As a result, it is easier when inserting the ground electrode to align the ground electrode in such a way that the depression is aligned to fit the center electrode.DRAWINGFIG. 1 shows an example of a spark plug having a ground electrode inserted into two bores FIG. 2 shows an example of inserting the ground electrode into the two bores FIG. 3 shows the combustion chamber end of the spark plug according to the invention in sectionDESCRIPTION OF THE EMBODIMENTFIG. 1 a) shows a spark plug 1. the spark plug 1 has a longitudinal axis X which extends from the end on the combustion chamber side to the end of the spark plug 1 facing away from the combustion chamber. The spark plug 1 has a housing 2 which 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, said outer seal sealing a transition between the housing 2 and the cylinder head.The insulator 3 is arranged and fastened inside the housing 2. In the insulator 3, starting from its end facing away from the combustion chamber, a connecting bolt 6, a resistance element and a center electrode 4 are arranged, which are electrically contacted with one another. The center electrode 4 typically protrudes from the insulator 3 at the combustion chamber-side end thereof and, in this example, into the interior of the housing 2.In this example, the ground electrode 5 is inserted into two bores 20 formed in the housing wall. The bores 20 are, for example, through-bores, which each extend from the outside to the inside of the housing 2. The ground electrode 5 is rod-shaped, i.e. the ground electrode 5 has a cylindrical shape with round base surfaces. The ground electrode 5 forms the axial spark gap together with the center electrode 4.In FIG. 1 b), the ground electrode 5 according to the invention is again shown separately for better illustration. The ground electrode 5 is rod-shaped with a depression 50 on the side 51. At the end face 52, the rod-shaped ground electrode 5 has a notch 53 which serves to indicate the position of the depression 50 on the side 51 of the ground electrode 5 in order that the ground electrode 5 can be aligned in a fitting manner with respect to the center electrode 4.FIG. 2 shows how the ground electrode 5 is introduced from the outside through one of the bores 20 (FIG. 2 a) and is pushed through the bore 20 (FIG. 2 b) until the ground electrode 5 reaches the opposite bore 20 and is inserted therein (FIG. 2 c).The arrow indicates the direction of movement of the ground electrode 5. In this case, the notch 53 on the end face 52 of the ground electrode 5 helps to align the electrode correctly with respect to the center electrode 4.FIG. 3 shows the combustion chamber-side end of the spark plug 1 in a sectional illustration. It can be seen how the ground electrode 5 spans the interior of the housing 2 like a bridge and thus also the center electrode 4. Accordingly, an axial spark gap is formed between the center electrode 4 and the ground electrode 5. It can also be seen easily in FIG. 3 that the ground electrode 5 is inserted with both ends in the housing 2 and thereby has a good thermal connection to the housing 2.The recess 50 on the side 51 of the ground electrode 5 has a width B of diameter of the igniting element 55 plus 2 mm.

Claims

Spark plug (1) for a hydrogen-operated internal combustion engine having a longitudinal axis X, having • 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 which is formed between the ground electrode (5) and the central electrode (4) within the housing (2), characterized in that the housing (2) has two opposing bores (20) in which the ground electrode (5) is arranged, and in that the ground electrode (5) has a depression (50) on its side (51), wherein the ground electrode (5) is arranged such that the depression (50) is axially opposite the central electrode (4).Spark plug (1) according to Claim 1, characterized in that the ground electrode (5) has a cylindrical shape with round end faces (52).Spark plug (1) according to one of the preceding claims, characterized in that an ignition element (55) is arranged in the depression (50) on the side (51) of the ground electrode (5).Spark plug (1) according to Claim 3, characterized in that the depression (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.Spark plug (1) according to either of the preceding Claims 3 and 4, characterized in that the depression (50) is as deep as the ignition element (55) is as high in the axial direction, at least in the axial direction.Spark plug (1) according to one of the preceding claims, characterized in that the ground electrode (5) has, on at least one end face (52), a notch (53) which indicates the position of the depression (50) on the ground electrode (5).

Images