Spark plug with improved sealing properties
Patent Information
- Application Number
- EP2023745467
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-26
- Filing Date
- 2023-07-20
- Publication Date
- 2025-07-02
AI Technical Summary
Existing spark plugs fail to provide an effective seal between the outer housing and the cylinder head, allowing gases from the combustion chamber to escape, as conventional washer-like sealing rings do not adequately prevent gas leakage.
A metallic sealing ring with a first region perpendicular to the central axis and a second region at an acute angle is integrated into the spark plug housing, creating additional sealing areas and increasing the overall sealing surface, which is captured within a recess in the housing for easy installation.
The design significantly enhances the seal between the spark plug and the cylinder head, preventing gas leakage while simplifying the installation process and improving heat transfer.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] title
[0003] Spark plug with improved sealing properties
[0004] State of the art
[0005] The present invention relates to a spark plug with improved sealing properties on an outer housing of the spark plug when the spark plug is screwed onto, for example, a cylinder head or the like.
[0006] Spark plugs are known in various designs from the prior art. One problem with spark plugs is that the spark plug, which is arranged in a spark plug bore in a cylinder head, must also provide a seal on the outer circumference of the spark plug between the spark plug and the cylinder head. A washer-like sealing ring made of metal is typically used for this purpose. For example, DE102016 110 880 A1 shows a spark plug with a sealing ring in the shape of a washer, which is pushed onto a housing and shrunk in a subsequent post-forming step to be held captively on the spark plug over a threaded section of the housing.
[0007] Disclosure of the invention
[0008] The spark plug according to the invention with the features of claim 1 has the advantage that a seal between the spark plug and a cylinder head is significantly improved by means of a metallic sealing ring. This reliably prevents gases from the combustion chamber from escaping to the outside via the gap between the cylinder head and the spark plug. This is achieved according to the invention in that the spark plug has a center electrode and a ground electrode, between which an ignition gap is formed. Furthermore, the spark plug comprises an insulator and a metallic housing as well as a metallic sealing ring arranged on the outside of the housing. The sealing ring is designed to seal between the cylinder head and the spark plug. The metallic sealing ring has a first ring region and a second ring region.The first ring region is aligned perpendicular to a central axis XX of the spark plug and the second ring region is aligned at an acute angle a to the central axis XX of the spark plug. The first ring region, which is aligned perpendicular to the central axis, is aligned parallel to a shoulder on the housing. The second ring region is arranged on the inner circumference of the first ring region. The first and second ring regions of the metallic sealing ring thus ensure that not only is there a seal in a plane perpendicular to the central axis of the spark plug, as with a washer, but that two different sealing regions are provided on the metallic sealing ring. A first sealing region on the first ring region of the sealing ring is perpendicular to the central axis of the spark plug and is therefore provided as in the prior art when a washer is used as a sealing ring.The second ring area is arranged at an acute angle a to the central axis, creating an additional second sealing area in a different plane. The second sealing area on the second ring area is conical. This also allows the overall sealing surface between the metal sealing ring and the spark plug or cylinder head to be enlarged.
[0009] The subclaims show preferred developments of the invention.
[0010] Preferably, the housing has a recess in which the sealing ring is completely arranged. This allows the metal sealing ring to be securely mounted on the spark plug housing, which significantly simplifies spark plug installation. The metal sealing ring is thus integrated into the housing by the recess in the housing.
[0011] Preferably, adjacent to the recess in the housing in the combustion chamber side of the spark plug, a thread for screwing the spark plug into the cylinder head is formed.
[0012] More preferably, the recess formed in the housing is designed as a circumferential groove with a first and second wall and a base with three base regions. The first wall is preferably aligned parallel to the central axis of the spark plug. The second wall is preferably angled or aligned at a right angle to the central axis of the spark plug. The three base regions are preferably arranged such that the base has a first region perpendicular to the central axis, a second region parallel to the central axis, and a third region arranged at an angle to the central axis and connecting the first and second regions.
[0013] According to a particularly preferred embodiment of the invention, the surface roughness of the metallic sealing ring is greater than the surface roughness of the housing and / or the cylinder head. The different surface roughnesses result in improved sealing during spark plug assembly, since the higher surface roughness enlarges the sealing surface between the housing and the metallic sealing ring, as well as between the metallic sealing ring and the cylinder head.
[0014] Further preferably, the structure of the metallic sealing ring is such that a first leg length L1 of the first ring region is greater than or equal to a second leg length L2 of the second ring region.
[0015] Further preferably, the first and second ring regions of the metallic sealing ring have the same thickness and / or the same mass.
[0016] The angle a between the second ring region and the central axis is preferably in a range of 40° to 50° and is particularly preferably 45°.
[0017] The spark plug is preferably a hook-type spark plug, a pre-chamber spark plug, or a spark plug with an ignition gap within the housing. The housing of the spark plug is preferably made of a metallic material, with the housing preferably having a greater hardness than the metallic sealing ring.
[0018] Brief Description of the Drawing A preferred embodiment of the invention is described in detail below with reference to the accompanying drawing. In the drawing:
[0019] Figure 1 is a schematic, partially sectioned view of a
[0020] Spark plug according to a preferred embodiment of the invention,
[0021] Figure 2 is a schematic sectional view of a mounted spark plug in a cylinder head, where for clarity only the cylinder head, the housing and the sealing ring are shown and
[0022] Figure 3 is a schematic sectional view of the metallic sealing ring of Figures 1 and 2.
[0023] Preferred embodiment of the invention
[0024] A spark plug 1 according to a preferred embodiment of the invention will be described in detail below with reference to Figures 1 to 3.
[0025] As can be seen from Figure 1, the spark plug 1 is a hook spark plug with an insulator 2, preferably made of a ceramic material, and a metallic housing 3. The spark plug 1 further comprises a center electrode 4 and a ground electrode 5, which are connected to the housing 3.
[0026] An ignition gap is formed between the center electrode 4 and the ground electrode 5 in a known manner.
[0027] The spark plug 1 further comprises a metallic sealing ring 6, which is arranged on an outer side of the housing 3. The metallic sealing ring 6 is designed to seal against a cylinder head 8.
[0028] Sealing by means of the metallic sealing ring 6 is necessary to prevent gases from the combustion chamber from escaping to the environment via the gap between the spark plug 1 and the cylinder head 8. The metallic sealing ring 6 is shown in detail in Figures 2 and 3. The sealing ring 6 comprises a first ring region 61 and a second ring region 62 and is formed as a single-piece component. The second ring region 62 is arranged on the inner circumference of the first ring region 61.
[0029] The first ring region 61 and the second ring region 62 are arranged such that the first ring region 61 is arranged perpendicular to a central axis XX, and the second ring region 62 is arranged at an acute angle a of 45° to the central axis XX. As can be seen from Figure 3, a first leg length L1 of the first ring region 61 is equal to a second leg length L2 of the second ring region 62.
[0030] The metallic sealing ring 6 with first and second ring regions 61, 62 can be produced, for example, by a forming process.
[0031] As can be seen in particular from Figures 1 and 2, a recess 30 is formed in the housing 3 for receiving the metallic sealing ring 6. The recess 30 on the housing 3 is arranged in a transition region between a shoulder 34 of the housing 3 and a fixing region 35, in particular a threaded region, of the housing 3 for fixing the spark plug to the cylinder head 8.
[0032] The recess 30 comprises a first wall 31, which is aligned parallel to the central axis XX of the spark plug, a second wall 32, which is aligned perpendicularly or angled, in particular at 45°, to the central axis XX, and a bottom 33. The bottom 33 connects the first wall 31 to the second wall 32.
[0033] The base 33 comprises a first region 33a perpendicular to the central axis XX, a second region 33b parallel to the central axis XX, and a third region 33c at an acute angle to the central axis XX, with the third region 33c connecting the first region to the second region. The angle corresponds to the angle α on the metallic sealing ring between the first and second ring regions 61, 62.
[0034] As can be seen particularly in Figure 2, the metallic sealing ring 6 is completely accommodated in the recess 30. As a result, the metallic sealing ring 6 is securely positioned on the housing 3. This facilitates the installation of the spark plug in the cylinder head 8.
[0035] As can further be seen from Figure 2, in the assembled state of the metallic sealing ring 6, an empty receiving area 7 is formed in the recess 30. The receiving area 7 is essentially formed on the second area 30b of the recess 30 and serves as a free area to receive material which is displaced by deformation of the metallic sealing ring 6 during assembly of the spark plug in the cylinder head 8.
[0036] As can be seen from Figure 2, in the assembled state of the spark plug 1 in the cylinder head 8, a first sealing area 11 is created between the first ring area 61 and a sealing shoulder 81 on the cylinder head 8, as well as a second sealing area 12 between a chamfer 82 on the cylinder head and the second ring area 62. Thus, a sealing surface between the sealing ring 6 and the cylinder head 8 can be enlarged.
[0037] Furthermore, a surface roughness of the sealing ring 6 is greater than a surface roughness of the cylinder head 8. This further increases the tightness between the sealing ring and the cylinder head.
[0038] The surface roughness of the sealing ring 6 is also preferably greater than a surface roughness of the housing 3, whereby the seal between the housing and the sealing ring 6 is also improved.
[0039] Furthermore, the inventive design of the sealing ring 6 enables improved heat transfer between the spark plug and the cylinder head.
[0040] The receiving area 7 in the recess 30 further enables a defined deformation of the sealing ring 6 during assembly, thus ensuring a secure seal between the spark plug and the cylinder head. Installation of the sealing ring 6 in the recess is also very easy. Furthermore, by positioning the sealing ring 6 in the recess 30, no further steps, such as shrinking or the like, are required to securely mount the sealing ring 6 on the spark plug.
Claims
Claims 1. Spark plug, comprising: - a center electrode (4) and a ground electrode (5), - an insulator (2), - a metallic housing (3) and - a metallic sealing ring (6) arranged on an outer side of the housing (3), designed for sealing against a cylinder head (8), - wherein the sealing ring (6) has a first annular region (61) oriented perpendicular to a central axis XX of the spark plug and a second annular region (62) oriented at an acute angle a to the central axis XX of the spark plug, wherein the first annular region (61) is parallel to a shoulder (34) on the housing (3) and the second annular region (62) is arranged on the inner circumference of the first annular region (61).
2. Spark plug according to claim 1, wherein the housing (3) has a recess (30) in which the metallic sealing ring (6) is completely arranged.
3. Spark plug according to claim 2, wherein the recess (30) in the housing (3) is a circumferential groove with a first wall (31), a second wall (32) and a bottom (33) with three bottom regions.
4. Spark plug according to claim 2 or 3, wherein the base (33) has a first region (33a) perpendicular to the central axis XX, a second region (33b) parallel to the central axis XX and a third region (33c) at an acute angle to the central axis XX, the third region (33c) connecting the first to the second region (33a, 33b).
5. Spark plug according to claim 4, wherein the recess (30) has a receiving area (7) not filled by the sealing ring (6), which is designed as a material receiving area in order to accommodate a material which is formed during assembly of the Spark plug on the cylinder head to accommodate deformed material of the sealing ring (6). Spark plug according to one of the preceding claims, wherein a surface roughness of the sealing ring (6) is greater than a surface roughness of the housing (3) and / or a surface roughness of the cylinder head (8). Spark plug according to one of the preceding claims, wherein a first leg length L1 of the first ring region (61) is greater than or equal to a second leg length L2 of the second ring region (62). Spark plug according to one of the preceding claims, wherein the first ring region (61) and the second ring region (62) have the same thickness and / or wherein the first ring region (61) and the second ring region (62) have the same mass. Spark plug according to one of the preceding claims, wherein the acute angle α between the first and second ring regions (61, 62) is 45°.