Spark plug housing with a captively arranged outer seal, spark plug having same, and method for mounting the outer seal on the housing

Abstract

A spark plug housing (2) with an outer seal (3), wherein the housing (2) has a longitudinal axis X and a longitudinal bore, whereby the housing (2) has an inner side (20) and an outer side (21), a thread (22) with an outside diameter DT and a projection (25) with an outside diameter DA being formed on the outer side (21) of the housing (2), wherein the housing (2) has a thread-free portion (26) with the outside diameter Du between the thread (22) and the projection (25).

Description

[0001] R. 401488

[0002] - 1 -

[0003] Description

[0004] title

[0005] Spark plug housing with captive outer seal, spark plug and method for mounting the outer seal on the housing

[0006] State of the art

[0007] The present invention relates to a spark plug housing with an outer seal which is arranged on the housing in a captive manner, as well as a spark plug with the housing and the captive outer seal and a mounting method for the outer seal on the housing.

[0008] Spark plugs have a housing and an outer seal on its exterior. The primary function of this seal is to seal the area between the spark plug housing and the cylinder block in which the spark plug is mounted. For convenient installation and removal of the spark plug in the cylinder block, the outer seal is attached to the housing as a captive component, allowing it to be transported, installed, and removed along with the spark plug. An example of a spark plug with a captive outer seal and its manufacture is disclosed in DE 102012 207319 A1. In this design, the outer seal is first attached to the housing, and then the thread is formed on the outside of the housing. The inner radius of the outer seal is smaller than the outer diameter of the thread, thus preventing the outer seal from being lost.However, the outer seal can become misaligned with one thread, which can lead to damage to the thread.

[0009] It is important that during the manufacture of the spark plug, and especially during the installation of the outer seal on the spark plug, the outer seal does not interfere with the external thread of the spark plug formed on the housing and damage the thread. R. 401488

[0010] - 2 -

[0011] Furthermore, it has been shown that, in addition to ensuring the outer seal is securely attached to the spark plug housing, it may also be necessary to replace the outer seal after removing the spark plug from a cylinder head so that the spark plug can be reinstalled. Ideally, the new outer seal should then be securely attached to the spark plug without damaging the threads. This is not possible with the spark plug and its manufacturing process according to DE 10 2012 207319 A1.

[0012] The object of the present invention is to provide a spark plug housing with a captive outer seal in which the outer seal does not interfere with the thread and in addition the outer seal can also be replaced and the new outer seal can also be mounted in such a way that it is also captive on the housing, as well as a method for mounting the outer seal on the spark plug housing.

[0013] Advantage of the invention / Disclosure of the invention

[0014] This problem is solved by the spark plug housing according to the invention and the claimed assembly method.

[0015] The invention relates to a spark plug housing with an external seal. The housing has a longitudinal axis X and a longitudinal bore, giving it an inside and an outside. On the outside of the housing, a thread with an outside diameter DT and a shoulder with an outside diameter DA are formed, the housing having a threadless section with a diameter Du between the thread and the shoulder. An external seal with an inside diameter DR is arranged on the housing between the shoulder and the thread on the threadless section. The external seal has a chamfer on its inside. The threadless section on the housing has a projection designed to ensure that the external seal is securely attached to the housing.

[0016] The interaction of the chamfer on the inside of the outer seal and the projection on the unthreaded section ensures that the outer seal is securely attached to the housing and is no longer held by the thread. Interference between the outer seal and the thread is prevented in the case of R. 401488.

[0017] - 3 -

[0018] The projection on the unthreaded section of the housing prevents the outer seal from slipping or sliding off during assembly or subsequent transport or similar processes. The projection acts like a hook or barb for the outer seal and prevents it from slipping or sliding off.

[0019] The shoulder of the housing acts as a sealing seat, featuring a sealing surface whose surface normal is parallel to the longitudinal axis of the housing. When the spark plug housing is screwed into the cylinder block, the outer seal rests against the sealing surface of the shoulder.

[0020] The outer seal is located on the combustion chamber side of the housing shoulder and on the side of the thread facing away from the combustion chamber. The outer seal has an inner surface that is radial to the longitudinal axis of the housing and a combustion chamber-side end face. A chamfer is formed around the circumference between the combustion chamber-side end face and the inner surface of the outer seal, resulting in a shorter inner length for the outer seal than its maximum length measured parallel to the longitudinal axis of the housing.

[0021] The inner surface of the outer seal is framed by the unthreaded section and its projection. The projection extends into the volume not filled by the outer seal due to the chamfer. Specifically, the chamfer is designed with a length parallel to the longitudinal axis and an angle relative to the inner surface of the outer seal such that when the outer seal rests against the sealing surface of the shoulder, the projection of the unthreaded section does not contact the outer seal. The projection and the chamfer surface are not in contact with each other. When projected along the longitudinal axis of the housing, an overlap is observed between the projection and the outer seal.The interaction of the chamfer and the projection ensures that the outer seal is held securely on the unthreaded section of the housing and, together with the sealing surface of the shoulder, can seal the gap between the cylinder head and the housing when a spark plug is screwed into a cylinder head.

[0022] Advantageous embodiments of the invention are the subject of the dependent claims. R. 401488

[0023] - 4 -

[0024] In an advantageous design of the spark plug, the projection is formed around the outside of the housing on the unthreaded section.

[0025] This has the advantage that the outer seal is securely held along the circumference of the housing.

[0026] In a first alternative design of the spark plug, the projection is formed on a partial area of ​​the unthreaded section on the outside of the housing.

[0027] In a second alternative embodiment, several projections are formed on the unthreaded section on the outside of the housing, which are formed section by section along a circumference of the unthreaded section. In particular, areas with and without projections alternate along the circumference of the unthreaded section.

[0028] These two alternative designs have the advantage that less material needs to be formed into a projection or multiple projections on the unthreaded section, or that different manufacturing processes are available for forming the projection compared to a circumferential projection. In particular, if the outer seal is first fitted onto the housing and then the projection on the unthreaded section of the housing is formed by forming material from that section, it is advantageous to form the projection in a partial area or to create multiple projections, formed section by section, on the unthreaded section.

[0029] In a further development of the spark plug, the housing has an outer diameter DH at the projection, where DH is larger than the outer diameter Du of the unthreaded section without the projection, and where DH is larger than the inner diameter DR of the outer seal and DH is larger than the outer diameter DT of the thread. This ensures that the projection, and not the thread, securely holds the outer seal in place. Specifically, the inner diameter DR is larger than the outer diameter DT of the thread, ensuring that the outer seal does not have to contact the thread during assembly. Furthermore, the inner diameter DR is larger than the outer diameter Du of the unthreaded section at one point on the section without the projection. This allows the outer seal to be easily positioned on the unthreaded section. R. 401488

[0030] - 5 -

[0031] Furthermore, it is also advantageous if the outer diameter of the outer seal is greater than or equal to the outer diameter DA of the housing at the shoulder. This has the advantage that when the spark plug is screwed into the cylinder head, the housing does not touch the cylinder head wall.

[0032] Furthermore, it is also advantageous if the outer seal, measured parallel to the longitudinal axis of the spark plug, is longer than the unthreaded shoulder. This ensures sufficient outer sealing material so that the seal can deform when the spark plug housing is screwed into a cylinder head, thus achieving an adequate seal.

[0033] Furthermore, the invention also relates to a spark plug which has a housing according to the invention with an outer seal, an insulator arranged inside the housing, a center electrode arranged inside the insulator, a ground electrode and an ignition gap formed between the ground electrode and the center electrode.

[0034] The invention also includes a method for mounting an external seal on a spark plug housing, comprising the following steps:

[0035] • Providing a spark plug housing without an external seal, wherein the thread on the outside of the housing has an outer diameter of DT,

[0036] • Providing an outer seal with a chamfer on its inside, wherein the outer seal has an inner diameter of DR and D is greater than DT,

[0037] • Placing the outer seal on the outside of the housing on a threadless section located between the thread and a shoulder of the housing,

[0038] wherein either a projection is formed on the unthreaded section before the outer seal is placed on the outside of the housing, which is designed to hold the outer seal securely on the housing,

[0039] or alternatively, after the outer seal has been placed on the outside of the housing, a projection is formed on the unthreaded section, designed to hold the outer seal securely to the housing. R. 401488

[0040] - 6 -

[0041] The projection on the unthreaded section has the advantage that the outer seal is held securely on the unthreaded section, preventing it from interfering with the thread by tilting the outer seal on a thread turn.

[0042] By means of this method according to the invention, in particular the spark plug housing described above with a captive outer seal can be produced.

[0043] In a first embodiment of the method, the projection is formed after the outer seal has been placed, with the projection being formed at least in one section on the unthreaded shoulder by deforming part of the housing at the unthreaded section. For example, the projection is formed at several points on the unthreaded section by deforming the material using a punching operation. For example, a punching tool is guided parallel to the longitudinal axis of the housing so that the projections are created and the outer seal is securely mounted to the housing. This process creates, for example, several projections section by section along the circumference of the unthreaded section, with the projections being spaced apart from each other.

[0044] This design has the advantage that the outer seal can be easily and effortlessly slid over the housing and its threads to the unthreaded section. Furthermore, when replacing the outer seal, material remains available to form new protrusions that securely hold the new outer seal to the housing.

[0045] In a second embodiment of the method, the threadless section of the housing already has one or more projections before the outer seal is placed, wherein the housing has an outer diameter DH at the projection and DH is smaller than the inner diameter D of the outer seal at the point of placement of the outer seal.

[0046] In a first further development of the second embodiment of the method, after the outer seal has been placed, the outer seal is reshaped on its inner side at least in one section, so that the inner diameter DRI of the outer seal is reduced in this section and the new R. 401488

[0047] - 7 -

[0048] The inner diameter DR3 of the outer seal at this section is smaller than the outer diameter DH of the housing at the projection, so that the projection securely holds the outer seal in place. For example, a stamping tool is guided parallel to the longitudinal axis of the housing, creating projections at several points on the inside of the outer seal. This reduces the inner diameter of the outer seal at these points, ensuring that the outer seal is securely mounted to the housing.

[0049] In a further development of the second embodiment of the method, after the outer seal has been placed, it is reshaped so that it acquires a non-circular form. This results in the outer seal having at least two different inner diameters, where one inner diameter DRA is smaller than the other inner diameter DRB, and where DRA is smaller than DH, so that the projection securely holds the outer seal in place. Specifically, DRA is smaller than DRI and DRB is larger than both DRI and DH. The deformation forces act, for example, laterally or radially with respect to the longitudinal axis of the housing on the ring and deform it.

[0050] The procedures according to the two further developments of the second embodiment have the advantage that they can also be easily applied when changing the outer seal, so that the new outer seal is again securely placed on the spark plug housing.

[0051] In a third embodiment of the method, the unthreaded section already has one or more projections before the outer seal is placed, wherein the housing has an outer diameter DH at the projection, and DH is larger than the inner diameter DR of the outer seal, and that the outer seal is heated for placement, so that the inner diameter DRH of the outer seal increases and the outer seal can be slid over the projection, wherein after placement the outer seal cools down again, so that the inner diameter DR ( 2. The outer seal is smaller than the outer diameter DH of the housing at the projection, and the projection securely holds the outer seal in place.

[0052] This design has the advantage that it can be easily applied even when replacing the outer seal, ensuring that the new outer seal is securely attached to the spark plug housing. R. 401488

[0053] - 8 -

[0054] drawing

[0055] Figure 1 shows an example of a spark plug housing according to the invention with a captive outer seal.

[0056] Figure 2 shows a partial section of Figure 1 in cross-section.

[0057] Figure 3 shows a first example of an assembly method according to the invention for the outer seal on the housing.

[0058] Figure 4 shows a second example of an assembly method according to the invention for the outer seal on the housing.

[0059] Figure 5 shows a third example of an assembly method according to the invention for the outer seal on the housing.

[0060] Figure 6 shows a fourth example of an assembly method according to the invention for the outer seal on the housing.

[0061] Description of the exemplary embodiment

[0062] In the figures, identical or functionally equivalent components are named the same and provided with the same reference symbols.

[0063] Figure 1a shows a spark plug housing 2 according to the invention with a captive outer seal 3.

[0064] The spark plug housing 2 has a longitudinal bore parallel to the longitudinal axis X of the housing 2. Due to the longitudinal bore, the housing 2 has an inner surface 20 and an outer surface 21. A thread 22 is arranged on the outer surface 21 of the housing 2, with which the spark plug can be screwed into a cylinder block. Furthermore, a shoulder 25 and a polygonal section 29 are arranged on the outer surface 21 of the housing 2. The polygonal section 29 serves to allow a tool to be applied to the spark plug so that the spark plug can be screwed into and out of a cylinder block. The shoulder 25 serves as a sealing seat, which has a sealing surface 251, the R. 401488

[0065] - 9 -

[0066] The surface normal is parallel to the longitudinal axis X of the housing 2. When the spark plug housing 2 is screwed into the cylinder block, the outer seal 3 rests against the sealing surface 251 of the shoulder 25. The outer seal 3 is located on the combustion chamber side of the shoulder 25 and on the side of the thread 22 facing away from the combustion chamber.

[0067] Figure 1b shows a partial section of the spark plug housing 2 according to the invention without an external seal.

[0068] The partial view shows the end of the thread 22 facing away from the combustion chamber, a threadless section 26, and the shoulder 25 with its sealing surface 251. In Figure 1a), the external seal 3 is arranged on the threadless section 26, which has been omitted in Figure 1b) to better illustrate the threadless section 26. The threadless section 26 has an outer diameter of Du. At the combustion chamber-side end of the threadless section 26, a projection 24 is formed, corresponding to a hook serving as a retaining device. The threadless section 26 has an outer diameter DH at the projection 24, which is larger than the outer diameter Du of the threadless section 26 at a point without the projection 24. This results in an undercut between the combustion chamber-facing end of the projection 24 and the sealing surface 251 of the shoulder 25. The thread 22 has an outer diameter of DT, which is smaller than the outer diameter DH of the projection 24.The paragraph 25 has an outer diameter DA that is larger than the outer diameters DT, DH and Du of the thread 22, projection 24 and unthreaded section 26.

[0069] Figure 2 shows a partial section in 2a) and its enlargement in 2b) of the spark plug housing 2 with external seal 3 according to the invention from Figure 1 in a sectional view. Here, the external seal 3 can be seen at the unthreaded section 26. The external seal 3 has an inner diameter DR, with the external seal 3 having a chamfer 31 on its inner surface 3b. Instead of an inner corner facing the combustion chamber, the external seal 3 has a chamfer 31. The chamfer 31 extends from the inner surface 3b of the external seal 3 to the combustion chamber-side surface 3a of the external seal. The chamfer on the outer surface 3c of the external seal 3 is optional. In this example, the external seal 3 is parallel to the longitudinal axis X of the housing 2 and longer than the unthreaded section 26. Furthermore, the outer diameter of the external seal 3 is larger than the outer diameter DA of the shoulder 25, so that the external seal 3 projects radially beyond the shoulder 25. R. 401488

[0070] - 10 -

[0071] In this example, between the last thread of the thread 22 and the unthreaded section 26 with the projection 24, there is another unthreaded section where the housing 2 has an outer diameter DG that is smaller than the outer diameter DT of the thread 22 and smaller than the outer diameter Du of the unthreaded section 26 with the projection 24, so that between the unthreaded section 26 with projection and the further unthreaded section there is a jump in the housing outer diameter and a corresponding surface 246.

[0072] In this example, the projection 24 has a rounded contour facing the combustion chamber and an edge contour facing the shoulder 25. The interaction of these contours allows the outer seal 3 to be easily slid over the projection 24 from the combustion chamber side and is then prevented by the edge from sliding back off the housing 2 towards the combustion chamber. The projection 24 acts like a hook, specifically a barb. The outer seal 3 is securely held in place within the unthreaded section 26 of the housing 2. Instead of a rounded contour, the projection 24 can also have an angled contour.

[0073] The effect of the projection 24 as a hook is enhanced by the fact that the outer seal 3 has the chamfer 31 on its inner side. The projection 24 extends into the volume that is freed up by the chamfer 31 and is not occupied by the volume of the outer seal 3. Conversely, a portion of the outer seal 3 extends into the space of the undercut that results from the projection 24 on the unthreaded section 26.

[0074] Figure 2b shows the threadless section 26 with projection 24 and the inner surface 3b of the outer seal 3 with the chamfer 31 in magnification. This magnification clearly shows that the inner surface 3b of the outer seal 3 projects into the space of the undercut, and the projection 24 into the space created by the chamfer 31 on the inner surface of the outer seal 3. The projection 24 may contact the outer seal 3 at the chamfered surface, but this is not necessary. It is even desirable that the chamfer 31, in its length and development relative to the inner surface 3b of the outer seal 3, be designed such that the projection 24 and the outer seal 3 are non-contacting and exert no pressure R. 401488

[0075] - 11 -

[0076] exert pressure on each other and therefore do not cause any mechanical stress in the material.

[0077] Figure 3 illustrates various steps of a first method according to the invention for mounting the outer seal 3 on the housing 2. In Figure 3a), the spark plug housing 2 with thread 22, unthreaded section 26 with projection 24, and shoulder 25 is shown. The outer seal 3 is pushed over the thread. The inner diameter DR of the outer seal 3 is larger than the outer diameter DT of the thread 22. The projection 24, which has a larger outer diameter DH than the inner diameter D of the outer seal 3, is already positioned on the unthreaded section 26. Due to the combustion chamber-side rounded or chamfered contour of the projection 24, the outer seal 3 can be pushed over the projection 24 with a corresponding force F, as can be seen in Figure 3b). The force F is exerted on the outer seal 3 parallel to the longitudinal axis X of the housing 2 and uniformly along its circumference.In one variant of this method, the outer seal 3 is heated before being pushed on, so that the inner diameter DR. ( 2 increases in size, so that less force F is required to push the outer seal 3 over the projection 24. The increased inner diameter DR ( 2 is larger than the inner diameter DRU of the outer seal at room temperature. For assembly, the temperature of the outer seal 3 can also be chosen so high that the enlarged inner diameter DR (The outer diameter DH of the projection 24 is larger than the outer diameter DRH of the housing 2. The housing 2 remains at room temperature. After the outer seal 3 is slid over the projection 24 and positioned on the unthreaded section 26, the outer seal 3 cools back down to its previous temperature, for example, room temperature, and the inner diameter DRH decreases again, typically reaching the same temperature as the housing 2. Figure 3c shows the result of the assembly. The outer seal 3 is securely attached to the housing 2.

[0078] Figure 4 illustrates the steps of an alternative assembly method for the outer seal 3 on the housing 2. As shown in Figure 4a), the projection 24 is already formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is slid onto the housing 2 and over the projection 24. In this method, the inner diameter DR of the outer seal 3 is larger than the outer diameter DH of the projection 24. The outer seal 3 can be slid over the projection 24 without significant force. R. 401488

[0079] - 12 -

[0080] and are placed on the unthreaded section 26. Figure 4b) shows how, after the outer seal 3 is placed, a lateral force F is applied to it, causing the outer seal 3 to deform. For example, the outer seal 3 was originally round and becomes elliptical after deformation. After deformation, the outer seal 3 has different diameters DRI and DR2. For example, for the two section planes AA and BB in Figures 4c) and d), the outer seal 3 with the different inner diameters DRI and DR2 is shown. In the first section plane AA, the inner diameter DR2 of the outer seal 3 is smaller than the outer diameter DH of the projection 24 (Figure 4c)). The outer seal 3 is thus securely attached to the unthreaded section 26. In the second section plane BB, the inner diameter DRI of the outer seal 3 is larger than the outer diameter DH of the projection 24 (Figure 4d)).

[0081] Figure 5 illustrates the steps of another alternative assembly method for the outer seal 3 on the housing 2. As shown in Figure 5a), the projection 24 is already formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is slid onto the housing 2 and over the projection 24. In this method, the inner diameter DR of the outer seal 3 is larger than the outer diameter DH of the projection 24. The outer seal 3 can be slid over the projection 24 and positioned on the unthreaded section 26 without significant force. Figure 5b) shows how, after the outer seal 3 has been positioned, a force F acting parallel to the longitudinal axis X of the housing 2 is applied to it, causing the outer seal 3 to deform radially on its combustion chamber-facing side 3a, particularly in the area of ​​the chamfer 31 on the inner side 3b of the outer seal 3.Using a tool, one or more notches 32 are created on the radially inner section of the outer seal 3, for example by punching. The notches 32 are distributed along the inner circumference of the outer seal 3 and spaced apart from each other. Due to the notches 32, the inner diameter DRI of the outer seal 3 is reduced in the area of ​​the notches 32, so that it is smaller than the outer diameter DH of the projection 24 and the outer seal 3 is securely positioned on the unthreaded section 26.

[0082] Figure 5c) shows the result of this assembly procedure. Due to the notches 32, part of the outer seal 3 is bent inwards and protrudes into the undercut of the unthreaded section 26. R. 401488

[0083] - 13 -

[0084] Figure 5 d) shows a top view of an outer seal 3 with notches 32. This illustration clearly shows how the inner diameter DR is smaller in areas with notches 32 than in areas 33 without notches.

[0085] With all the methods presented, the outer seal 3 can be securely mounted to the housing 2 both during spark plug production and when replacing an old outer seal 3. This is also possible in principle with the next method, but not as reliably as with the previous methods.

[0086] Figure 6 illustrates the steps of another alternative assembly method for the outer seal 3 on the housing 2. As shown in Figure 6a), no projection is formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is slid onto the housing 2. In this method, the projection 24 is formed on the unthreaded section 26 after the outer seal 3 has been placed on it. Similar to the method according to Figure 5, a deformation takes place by means of a force F acting parallel to the longitudinal axis X of the housing 2. In this example, the deformation occurs on the unthreaded section 26 of the housing 2, so that the projection 24 or several projections 24 are formed and hold the outer seal 3 securely on the unthreaded section 26, as can be seen in Figure 6b). One or more notches 27 are created on the unthreaded section 26 using a tool, for example, by punching.The notches 27 are distributed along the outer circumference of the unthreaded section 26 and spaced apart from each other. Because of the notches 27, the outer diameter of the unthreaded section 26 is increased so that it is larger than the inner diameter D of the outer seal 3, and the seal is thus securely attached to the unthreaded section 26.

[0087] Figure 6c) shows the result of this assembly process. The notches 27 cause part of the unthreaded section 26 to be bent outwards, resulting in the projections 24 in these areas.

[0088] For example, to replace the outer seal 3, the old projections can be removed and new projections 24 can be formed in previously notch-free areas, so that these new projections 24 can again securely hold the new outer seal 3 in place.

Claims

1. R. 401488 2.- 14 - 3. Claims 1. Spark plug housing (2) with an outer seal (3), wherein 5. • the housing (2) has a longitudinal axis X and a longitudinal bore, whereby the housing (2) has an inside (20) and an outside (21), wherein on the outside (21) of the housing (2) a thread (22) with an outside diameter DT and a shoulder (25) with an outside diameter DA are formed, wherein the housing (2) has a non-threaded section (26) with an outside diameter Du between the thread (22) and the shoulder (25), 6.• the outer seal (3) has an inner diameter DR and is arranged between the shoulder (25) and the thread (22) on the unthreaded section (26), 7. characterized by this, 8. that the outer seal (3) has a chamfer (31) on its inner side (3b) and that the housing (2) has a projection (24) on the unthreaded section (26) which is designed to ensure that the outer seal (3) is securely attached to the housing (2).

2. Housing (2) according to claim 1 , characterized in that the projection (24) is formed circumferentially on the outside of the housing (2) on the threadless section (26).

3. Housing (2) according to claim 1, characterized in that the projection (24) is formed on a partial area of ​​the unthreaded section (26) on the outside (21) of the housing (2) or that several projections (24) are formed on the unthreaded section (26) on the outside (21) of the housing (2), which are formed section by section along a circumference of the unthreaded section (26).

4. Housing (2) according to one of the preceding claims, characterized in that the housing (2) has an outer diameter DH at the projection (24), wherein DH is larger than Du and D and DT. R. 401488 12.- 15 - 5. Housing (2) according to one of the preceding claims, characterized in that the outer diameter of the outer seal (3) is greater than or equal to the outer diameter DA of the housing (2) at the shoulder (25).

6. Spark plug present, 15. • a housing (2) with an outer seal (3) according to one of claims 1 to 5, 16. • an insulator arranged inside the housing (2) 17. • a central electrode arranged inside the insulator, 18. • a ground electrode, 19. • an ignition gap formed between the ground electrode and the center electrode.

7. Method for mounting an outer seal (3) on a spark plug housing (2) according to one of claims 1 to 5, comprising the following steps: 21.• Providing a spark plug housing (2) without an external seal (3), wherein the thread (22) with an outer diameter of DT is formed on the outside of the housing (2), 22.• Providing an outer seal (3) with a chamfer (31) on its inner side, wherein the outer seal (3) has an inner diameter of DR and D is greater than DT, 23.• Placing the outer seal (3) on the outside of the housing (2) on a threadless section (26) located between the thread (22) and a shoulder (25) of the housing (2), 24. characterized in that, prior to placing the outer seal (3) on the outside of the housing (21), a projection (24) is formed on the unthreaded section (26) which is designed to hold the outer seal (3) securely on the housing (2), or that, after placing the outer seal (3) on the outside of the housing (21), a projection (24) is formed on the unthreaded section (26) which is designed to hold the outer seal (3) securely on the housing (2).

8. Method according to claim 7, characterized in that the projection (24) is formed after the outer seal (3) has been placed, wherein R. 401488 26.- 16 - 27. at least in a partial area of ​​the unthreaded section (26) the projection (24) is formed in which part of the housing material is reshaped on the unthreaded section (26).

9. Method according to claim 7, characterized in that, prior to placing the outer seal (3), the unthreaded section (26) of the housing (2) has a projection (24) or several projections (24), wherein the housing (2) has an outer diameter DH at the projection (24) and DH is smaller than the outer diameter DRI of the outer seal (3) at the point of placement of the outer seal (3).

10. Method according to claim 9, characterized in that after placing the outer seal (3) the outer seal (3) is reshaped on its inner side (3b) at least in one section, so that the inner diameter DR of the outer seal (3) is reduced in this section and the new inner diameter D 2 of the outer seal (3) in this section is smaller than the outer diameter DH of the housing (2) at the projection (24), so that the projection (24) holds the outer seal (3) securely.

11. Method according to claim 9, characterized in that after placing the outer seal (3) the outer seal (3) is reshaped so that the outer seal (3) has a non-round shape, whereby the outer seal (3) has at least two different inner diameters DI, D 2, wherein one inner diameter DRI is smaller than the second inner diameter D 2 and wherein DRI is smaller than DH, SO that the projection (24) holds the outer seal (3) securely.

12. Method according to claim 7, characterized in that, prior to the placement of the outer seal (3), the threadless section (26) already has one or more projections (24), wherein the housing (2) has an outer diameter DH at the projection (24) and DH is larger than the inner diameter DRH of the outer seal (3), and that for the placement of the outer seal (3) it is heated so that the inner diameter DR (2 of the outer seal (3) is enlarged and the outer seal (3) can be pushed over the projection (24), whereby after the outer seal (3) is placed it cools down again, so that the inner diameter DRH of the outer seal (3) is smaller than the outer diameter DH of the housing (2) when R. 401488 32.- 17 - 33. Protrusion (24) is and the protrusion (24) holds the outer seal (3) securely.

Images