Spark plug with improved ground electrode

Abstract

The invention relates to a spark plug comprising a center electrode (4), a ground electrode (5) and a housing (2), wherein the housing (2) has a receiving opening (20) provided for receiving the ground electrode (5), wherein a force-locking connection (11) is formed between the ground electrode (5) and the receiving opening (20) in the housing (2), wherein the ground electrode (5) has a cross section deviating from a circular shape, and wherein the cross section of the receiving opening differs from the cross section of the ground electrode (5) such that a free area (9) is formed between the ground electrode (5) and the receiving opening (20).

Description

Technical Field

[0001] The present invention relates to a spark plug, particularly a pre-combustion chamber spark plug, having an improved ground electrode and simplified manufacturability. Background Technology

[0002] Spark plugs with different design schemes are known from the prior art. A series of problems with spark plugs are particularly related to the securing of the ground electrode to the spark plug housing. Currently, the ground electrode is a cylindrical pin, which is fixed in a hole in the housing by press-fit. As an alternative or additional solution, the ground electrode can also be welded. However, the pressing process of the ground electrode into the spark plug housing requires a high force, which can lead to damage to the housing and / or the ground electrode itself, especially if the ground electrode is improperly positioned. In particular, when the housing thickness is relatively thin, deformation can occur in the housing area due to the pressing of the ground electrode. A defined gap must also be set between the ground electrode and the center electrode, which is difficult to achieve to some extent due to the pressing and / or welding processes. A spark plug is known from DE 10 2020 211583 A1, in which a blind hole is provided in the housing, and the ground electrode is pressed into the blind hole. The blind hole should ensure a precise ignition gap between the ground electrode and the center electrode. However, what is desired is a simplified and feasible solution for securing the ground electrode to the spark plug housing. Summary of the Invention

[0003] In contrast, the spark plug according to the invention, having the features of claim 1, has the advantage of enabling significantly easier assembly of the ground electrode into the spark plug housing. In particular, the invention avoids damage to the spark plug's ground electrode or housing. It also reduces the force required to introduce the ground electrode into the receiving opening in the spark plug housing. Furthermore, it is particularly advantageous that, during the fixing process, misaligned ground electrodes, for example due to tilting, can be immediately identified, allowing for rapid correction during the fixing process. This significantly reduces the spark plug defect rate.

[0004] According to the present invention, this is achieved by the following method: the spark plug includes a center electrode, a ground electrode, and a housing with a receiving opening. The receiving opening is provided for receiving the ground electrode. Here, a force-transmitting locking connection is formed between the ground electrode and the receiving opening in the housing. Furthermore, the ground electrode has a cross-section that is not circular. Furthermore, the cross-section of the receiving opening is different from the cross-section of the ground electrode. Therefore, a force-transmitting locking connection is formed between the ground electrode and the center electrode, wherein the cross-sectional shape of the ground electrode and the cross-sectional shape of the receiving opening are different. Therefore, in the assembled state, a free area is created between the ground electrode and the receiving opening.

[0005] The dependent claims indicate preferred improvements of the invention.

[0006] Preferably, the receiving opening in the housing is a through opening. That is, the receiving opening extends from the outer region of the housing to the inner region of the housing. This allows the ground electrode to be assembled starting from the outside of the spark plug.

[0007] The receiving opening is preferably a column and therefore has a circular cross-section.

[0008] Preferably, a plurality of free regions are formed between the grounding electrode and the receiving opening. Particularly preferably, all free regions are configured with the same cross-section. This is preferably achieved in such a way that the receiving opening is columnar and the outer periphery of the grounding electrode has a uniform shape that deviates from a circle.

[0009] Preferably, the grounding electrode has a cross-section with a substantially corrugated circumferential edge. Thus, a perimeter with crests and troughs is formed in the cross-section based on the radius of the circles at the troughs of the corrugated circumferential edge. Preferably, six crests and six troughs are provided.

[0010] More preferably, the grounding electrode has a star-shaped cross-section with multiple teeth, particularly triangular teeth. Here, the teeth are preferably constructed such that linear contact areas are created between the grounding electrode and the receiving opening, respectively, between the tips of the teeth and the inner peripheral region of the receiving opening.

[0011] The teeth of the grounding electrode are preferably formed such that the cross-sectional area of ​​the free region corresponds exactly to the cross-sectional area of ​​the teeth.

[0012] More preferably, the grounding electrode has a cross-section constructed as a constant-width curve (Gleichdick). Here, the constant-width curve structure is a cross-section with the same spacing from its center point to each edge region of the grounding electrode. Preferably, the constant-width curve structure is a Reuleaux triangle.

[0013] According to another preferred embodiment of the invention, the grounding electrode has a cross-section with multiple flattened portions. Edges are created through the flattened portions of the grounding electrode, wherein a force-transmitting locking connection between the grounding electrode and the receiving opening is formed at said edge. The flattened portions preferably have the same width.

[0014] Specifically, the grounding electrode is constructed with a quadrilateral cross-section, or an octagonal cross-section, or three flat sections and three circular arcs.

[0015] More preferably, the spark plug is a pre-combustion chamber spark plug.

[0016] More preferably, the spark plug has multiple ground electrodes, all of which are constructed identically. Attached Figure Description

[0017] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings: Figure 1 A schematic partial cross-sectional view of a spark plug according to a first embodiment is shown. Figure 2 The grounding electrode is shown to be fixed at Figure 1 A schematic diagram of the spark plug housing. Figure 3 It shows that it is fixed in Figure 1 A schematic cross-section of the ground electrode in the receiving opening of the spark plug housing. Figure 4 It shows Figure 1 A schematic three-dimensional diagram of the grounding electrode, and Figures 5 to 11 A schematic cross-sectional view of another preferred embodiment of the grounding electrode in its assembled state within a housing is shown. Detailed Implementation

[0018] The following is for reference. Figures 1 to 4 The spark plug 1 according to a preferred embodiment of the present invention will be described in detail below.

[0019] like Figure 1 As shown, spark plug 1 is a pre-combustion chamber spark plug having a metal housing 2 and an insulator 3. Furthermore, the spark plug includes a center electrode 4 located on the central axis XX of the spark plug and at least one laterally mounted ground electrode 5.

[0020] An external thread 21 is formed at the housing 2 for screwing the spark plug into the cylinder head of the internal combustion engine. Furthermore, the spark plug 1, configured as a pre-combustion chamber spark plug, includes a cover 6, which, together with a portion of the housing, defines the pre-combustion chamber 16 of the spark plug. Here, the center electrode 4 and the ground electrode 5 are arranged in the pre-combustion chamber 16.

[0021] The cover 6 has multiple overflow openings 7 and 8. The overflow openings 7 and 8 enable fluid connection between the pre-combustion chamber 16 and the combustion chamber 10 of the internal combustion engine.

[0022] Especially from Figure 2 As can be seen, housing 2 has a receiving opening 20 for grounding electrode 5.

[0023] Here, a force-transmitting locking connection 11 is constructed between the grounding electrode 5 and the receiving opening 20. In particular, as from... Figure 3As can be seen, the grounding electrode 5 has a non-circular cross-section. Here, the cross-section of the receiving opening 20 deviates from the cross-section of the grounding electrode 5. The receiving opening 20 has a cylindrical cross-section.

[0024] Therefore, as Figure 3 As shown in the assembled state, there is a free region 9 between the grounding electrode 5 and the receiving opening 20. The grounding electrode 5 of the first embodiment has a constant-width curve structure, which has the same spacing from the center point M relative to each circumferential point of the grounding electrode. Therefore, the grounding electrode 5 of the first embodiment has three edge-shaped contact areas 50. Here, arc-shaped free surfaces 51 are respectively provided between the contact areas 50.

[0025] As from Figure 2 As can be seen, the receiving opening 20 is constructed as a through opening in the housing 2. Due to the cylindrical cross-section of the receiving opening 20, which deviates from the cross-section of the grounding electrode 5, a significantly reduced assembly force F is required when the grounding electrode 5 is assembled into the receiving opening 20 (see...). Figure 2 Because the free area 9 is immediately visible in the top view once the grounding electrode 5 is introduced into the receiving opening 20 during assembly, any misalignment of the grounding electrode 5 during assembly can be immediately identified based on the different cross-sections of the free area 9. This can also be achieved before applying the force F for assembly by simply placing the grounding electrode 5 in the receiving opening 20 and inspecting the free area 9. Therefore, rapid intervention in case of misalignment during assembly is possible, thereby significantly reducing the defect rate due to misaligned grounding electrodes.

[0026] Furthermore, the reduced assembly force F prevents damage, such as preventing the housing 2 from bending during assembly, during the assembly of the grounding electrode 5 into the receiving opening 20, because the assembly force F is significantly less than the assembly force in the prior art, in which the cylindrical grounding electrode is forcefully and lockingly introduced into the cylindrical receiving opening.

[0027] Therefore, according to the present invention, the area of ​​the force-transmitting locking connection between the grounding electrode 5 and the receiving opening 20 can be significantly reduced, wherein, despite this, a sufficiently strong connection is still achieved between the grounding electrode 5 and the receiving opening 20.

[0028] Figures 5 to 11 A further preferred embodiment of the ground electrode 5 for a spark plug according to the invention is shown. Identical or functionally equivalent components are provided with the same reference numerals.

[0029] Figure 5A spark plug with a ground electrode 5 according to a second embodiment of the invention is shown. The ground electrode 5 of the second embodiment has a corrugated circumferential edge with alternating crests and troughs. In the trough region, a free region 9 is provided between the ground electrode 5 and the housing 2. Here, the crests and troughs are arranged such that the cross-section of the free region 9 is of the same size.

[0030] exist Figure 6 In the third embodiment shown, the grounding electrode 5 has a star-shaped cross-section with a plurality of triangular teeth 52. Here, the tip regions of the teeth form contact areas. Therefore, in the assembled state, a linear force-transmitting locking connection is formed at each end of the teeth. Figure 6 In the embodiment shown, the cross-section of the free region 9 is the same size as the cross-section of the tooth 52.

[0031] Figure 7 and Figure 8 The third and fourth embodiments of the present invention are shown, which substantially correspond to the third embodiment. Figure 7 In the embodiment shown, the number of teeth 52 is relative to Figure 6 A significant increase. Figure 8 An embodiment with a greater number of teeth 52 is shown.

[0032] Figure 9 A sixth embodiment of the invention is shown, wherein the grounding electrode 5 has a truncated portion 53. Figure 9 In this configuration, the grounding electrode 5 has eight truncated portions 53. This creates eight linear contact areas 50. Here, a free area 9 is formed between the truncated portions 53 and the receiving opening 20 (see [reference]). Figure 9 ).

[0033] Figure 10 A seventh embodiment of the invention with four flat sections 53 is shown. Here, the flat sections are chosen such that the contact area 50, which is fixed in the receiving opening 20 in a force-locking manner, is constructed in an arc shape. It should be noted that instead of an arc-shaped contact area 50, a flat section can also be formed at the contact area, so that each contact area produces two edge-shaped force-locking connection portions.

[0034] Figure 11 The eighth embodiment of the invention is shown, having three flat sections 53 and three arcuate regions 54. The arcuate regions 54 are configured to engage with the force-transmitting locking connection 11 of the receiving opening 20.

[0035] Compared to existing technologies, all described embodiments offer the advantage of reduced assembly force, thereby preventing damage to the grounding electrode and / or housing during assembly. Furthermore, by identifying the free region 9, incorrect assembly can also be directly identified during the assembly process.

Claims

1. A spark plug, comprising: - Central electrode (4). - Grounding electrode (5), and - Housing (2), wherein the housing (2) has a receiving opening (20) provided for receiving the grounding electrode (5). - Wherein, a force-transmitting locking connection (11) is formed between the grounding electrode (5) and the receiving opening (20) in the housing (2). - Wherein, the grounding electrode (5) has a cross-section that deviates from a circle, and - Wherein, the cross-section of the receiving opening (20) is different from the cross-section of the grounding electrode (5), such that a free region (9) is formed between the grounding electrode (5) and the receiving opening (20).

2. The spark plug according to claim 1, wherein, The receiving opening (20) in the housing is a through opening.

3. The spark plug according to any one of the preceding claims, wherein, The receiving opening (20) has a circular cross-section.

4. The spark plug according to any one of the preceding claims, wherein, Multiple free regions (9) are formed between the grounding electrode (5) and the receiving opening (20).

5. The spark plug according to any one of the preceding claims, wherein, The grounding electrode has a cross-section with a corrugated circumferential edge.

6. The spark plug according to any one of claims 1 to 4, wherein, The grounding electrode (5) has a star-shaped cross-section with multiple teeth (52).

7. The spark plug according to claim 6, wherein, The cross-sectional area of ​​the teeth of the grounding electrode is the same as the cross-sectional area of ​​the free region (9).

8. The spark plug according to any one of claims 1 to 4, wherein, The cross-section of the grounding electrode (5) is a constant width curve structure.

9. The spark plug according to any one of claims 1 to 4, wherein, The cross-section of the grounding electrode (5) has multiple flat sections (53).

10. The spark plug according to claim 9, wherein, The cross-section of the grounding electrode (5) has four flat sections, or eight flat sections, or three flat sections and three arc-shaped contact areas.

11. The spark plug according to any one of the preceding claims, wherein, The spark plug is a pre-combustion chamber spark plug.

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