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

Abstract

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), wherein on the outer side (21) of the housing (2) a thread (22) with an outer diameter D T and a paragraph (25) with an outer diameter D A are designed wherein the housing (2) has a threadless section (26) with an outer diameter D between the thread (22) and the shoulder (25). U exhibits

Description

State of the art

[0001] 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.

[0002] 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 10 2012 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.

[0003] It is important that during the manufacture of the spark plug, and especially during the assembly of the outer seal on the spark plug, the outer seal does not interfere with the external thread of the spark plug that is formed on the housing and damage the thread.

[0004] 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.

[0005] 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. Advantage of the invention / Disclosure of the invention

[0006] This problem is solved by the spark plug housing according to the invention and the claimed assembly method.

[0007] The invention relates to a spark plug housing with an external seal. The housing has a longitudinal axis X and a longitudinal bore, giving the housing an inside and an outside. On the outside of the housing is a thread with an outer diameter D. T and a paragraph with an outer diameter D Adesigned wherein the housing has a threadless section with a diameter D between the thread and the shoulder U The housing features an external seal between the shoulder and the thread on the unthreaded section, which has an inner diameter D. R The outer seal has a chamfer on its inner side. The unthreaded section on the housing has a projection designed to ensure that the outer seal is securely attached to the housing.

[0008] 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 in place by the threads. The projection on the unthreaded section of the housing prevents interference between the outer seal and the threads during installation, transport, or similar situations. The projection acts like a hook or barb for the outer seal, preventing it from slipping or sliding off.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] Advantageous further developments of the invention are the subject of the dependent claims.

[0013] In an advantageous design of the spark plug, the projection is formed around the outside of the housing on the unthreaded section. This has the advantage that the outer seal is securely held along the circumference of the housing.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] In a further development of the spark plug, the housing at the protrusion has an outer diameter D H , where D H larger than the outer diameter D U of the threadless section without projection and wherein D H larger than the inner diameter D Rthe outer seal and D H larger than the outer diameter D T of the thread. This ensures that the projection, and not the thread, securely holds the outer seal in place. In particular, the inner diameter D R larger than the outer diameter D T of the thread, which ensures that the outer seal does not have to touch the thread during assembly. Furthermore, the inner diameter D R larger than the outer diameter D U of the unthreaded section at a point on the section without a protrusion. This allows the external seal to be easily positioned on the unthreaded section.

[0018] Furthermore, it is also advantageous if the outer diameter of the outer seal is greater than or equal to the outer diameter D. Athe housing is located 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.

[0019] 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.

[0020] 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.

[0021] The invention also includes a method for mounting an external seal on a spark plug housing, comprising the following steps: • Providing a spark plug housing without an external seal, wherein the thread on the outside of the housing has an outer diameter of D T is trained • Providing an outer seal with a chamfer on its inner side, wherein the outer seal has an inner diameter of D R has and D R greater than D T is, • Placing the outer seal on the outside of the housing on a threadless section located between the thread and a shoulder of the housing, 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, or alternatively, after placing the outer seal on the outside of the housing, a projection is formed on the unthreaded section which is designed to hold the outer seal securely on the housing.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] In a second embodiment of the method, the unthreaded section of the housing already has one or more projections before the outer seal is placed, with the housing having an outer diameter D at the projection. H has and D H smaller than the inner diameter D R1 the outer seal is from the placement of the outer seal.

[0027] 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 D R1 the outer seal at this section is reduced in size and the new inner diameter D R3 the outer seal at this section is smaller than the outer diameter D H The housing is positioned 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.

[0028] In a second 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 shape. This results in the outer seal having at least two different inner diameters, one of which has an inner diameter D. RA is smaller than the second inner diameter D R3 and where D RA smaller than D H , so that the projection securely holds the outer seal in place. In particular, D RA smaller than D R1 and D RB greater than D R1 and D H The deformation forces act, for example, laterally or radially on the ring with respect to the longitudinal axis of the housing and deform it.

[0029] 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.

[0030] In a third embodiment of the method, the unthreaded section already has one or more projections before the outer seal is placed, with the housing having an outer diameter D at the projection. H has and D H larger than the inner diameter D R the outer seal, and that for placing the outer seal it is heated so that the inner diameter D Rt1 The outer seal is enlarged and can be pushed over the projection, whereby after the outer seal is placed it cools down again, so that the inner diameter D Rt2 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.

[0031] This design has the advantage that it can be easily used even when changing the outer seal, so that the new outer seal is also securely placed on the spark plug housing. drawing Fig. Figure 1 shows an example of a spark plug housing according to the invention with a captive outer seal. Fig. 2 shows a partial section of Fig. 1 in cross-section Fig. Figure 3 shows a first example of an assembly method according to the invention for the outer seal on the housing. Fig. Figure 4 shows a second example of an assembly method according to the invention for the outer seal on the housing. Fig. Figure 5 shows a third example of an assembly method according to the invention for the outer seal on the housing. Fig. Figure 6 shows a fourth example of an assembly method according to the invention for the outer seal on the housing. Description of the exemplary embodiment

[0032] In the figures, identical or functionally equivalent components are named the same and provided with the same reference symbols.

[0033] Fig. Figure 1a shows a spark plug housing 2 according to the invention with a captive outer seal 3.

[0034] The spark plug housing 2 has a longitudinal bore parallel to the longitudinal axis X of the housing 2. Due to this longitudinal bore, the housing 2 has an inner surface 20 and an outer surface 21. A thread 22 is provided on the outer surface 21 of the housing 2, allowing the spark plug to be screwed into a cylinder block. Furthermore, a shoulder 25 and a polygonal section 29 are provided on the outer surface 21 of the housing 2. The polygonal section 29 allows a tool to be applied to the spark plug, enabling it to be screwed into and out of the cylinder block. The shoulder 25 serves as a sealing seat, which has a sealing surface 251 whose 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.

[0035] Fig. Figure 1b shows a partial section of the spark plug housing 2 according to the invention without an external seal.

[0036] 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. Fig. 1 a) The outer seal 3 is arranged on the threadless section 26, which is in Fig. 1 b) was omitted to better illustrate the unthreaded section 26. The unthreaded section 26 has an outer diameter of D. U At the combustion chamber end of the unthreaded section 26, a projection 24 is formed, corresponding to a hook serving as a captive. The unthreaded section 26 has an outer diameter D at the projection 24. H , which is larger than the outer diameter D Uof the unthreaded section 26 at a point without a projection 24. This results in an undercut between the end of the projection 24 facing away from the combustion chamber and the sealing surface 251 of the shoulder 25. The thread 22 has an outside diameter of D T , which is smaller than the outer diameter D H The lead 24. The paragraph 25 has an outer diameter D A , which is larger than the outer diameter D T , D H and D U from the thread 22, projection 24 and unthreaded section 26.

[0037] Fig. 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. Fig. Figure 1 in a sectional view. Here, the outer seal 3 can be seen on the unthreaded section 26. The outer seal 3 has an inner diameter D. RThe outer seal 3 has a chamfer 31 on its inner surface 3b. Instead of a combustion chamber-side inner corner, the outer seal 3 has a chamfer 31. The chamfer 31 extends from the inner surface 3b of the outer seal 3 to the combustion chamber-side surface 3a of the outer seal. The chamfer on the outer surface 3c of the outer seal 3 is optional. In this example, the outer 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 outer seal 3 is larger than the outer diameter D. A of paragraph 25, so that the outer seal 3 projects radially beyond paragraph 25.

[0038] 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 D G has a diameter smaller than the outer diameter D Tof the thread 22 and smaller than the outer diameter D U of the threadless section 26 with the projection 24, so that between the threadless section 26 with projection and the further threadless section there is a jump in the housing outer diameter and a corresponding surface 246.

[0039] 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.

[0040] 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.

[0041] Fig. 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 magnified view. 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 on each other, thus preventing any mutual mechanical stress in the material.

[0042] In Fig. Figure 3 shows various steps of a first method according to the invention for mounting the outer seal 3 on the housing 2. Fig. 3 a) The spark plug housing 2 with thread 22, unthreaded section 26 with projection 24 and shoulder 25 is provided. The outer seal 3 is pushed over the thread. The inner diameter D is R the outer seal 3 is larger than the outer diameter D T of the thread 22. On the unthreaded section 26, the projection 24 is already arranged, which has a larger outer diameter D H than the inner diameter D R the outer seal 3. 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 shown in Fig. 3 b) can be seen. The force F is applied parallel to the longitudinal axis X of the housing 2 and uniformly along its circumference to the outer seal 3. In one variant of this method, the outer seal 3 is heated before being pushed on, so that the inner diameter D Rt2The increased inner diameter D means that less force F is required to push the outer seal 3 over the projection 24. Rt2 is larger than the inner diameter D Rt1 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 D Rt2 is larger than the outer diameter D H of the projection 24. The housing 2 remains at room temperature. After the outer seal 3 has been 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 D Rt1 The temperature decreases again and then usually has the same temperature as housing 2. Fig. 3 c) shows the result of the assembly. The outer seal 3 is securely attached to the housing 2.

[0043] In Fig. Figure 4 shows the steps of an alternative assembly procedure for the outer seal 3 on the housing 2. As in Fig. 4 a) As shown, the projection 24 is already formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is pushed onto the housing 2 and over the projection 24. In this method, the inner diameter D R the outer seal 3 is larger than the outer diameter D H of the projection 24. The outer seal 3 can be pushed over the projection 24 without significant force and positioned on the unthreaded section 26. In Fig. Figure 4 b) 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 D. R1 , D R2For example, for the two cutting planes AA and BB in the Fig. 4 c) and d) the outer seal 3 with the different inner diameters D R1 . D R2 The inner diameter D is shown in the first section plane AA. R2 the outer seal 3 is smaller than the outer diameter D H of the lead 24 ( Fig. 4 c)). The outer seal 3 is thus securely attached to the unthreaded section 26. In the second section plane BB, the inner diameter D R1 the outer seal 3 is larger than the outer diameter D H of the lead 24 ( Fig. 4 d)).

[0044] In Fig. Figure 5 shows the steps of another alternative assembly procedure for the outer seal 3 on the housing 2. As in Fig. 5 a) As shown, the projection 24 is already formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is pushed onto the housing 2 and over the projection 24. In this method, the inner diameter D R The outer seal 3 is larger than the outer diameter DH of the projection 24. The outer seal 3 can be pushed over the projection 24 without significant force and positioned on the unthreaded section 26. Fig. Figure 5 b) shows how, after the outer seal 3 has been placed, 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 inwards 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. One or more notches 32 are created on the radially inner section of the outer seal 3 using a tool, for example, by punching. The notches 32 are, for example, distributed along the inner circumference of the outer seal 3 and spaced apart from each other. Due to the notches 32, the inner diameter D R1 The outer seal 3 is reduced in the area of ​​the notches 32, so that it is smaller than the outer diameter D. H the projection 24 and the outer seal 3 are arranged in a captive manner on the threadless section 26.

[0045] In Fig. Figure 5 c) 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.

[0046] In Fig. Figure 5 d) shows a top view of an outer seal 3 with notches 32. In this illustration, it is clearly visible how the inner diameter D R in areas with notch 32 is smaller than in areas 33 without notch.

[0047] 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.

[0048] In Fig. Figure 6 shows the steps of another alternative assembly method for the outer seal 3 on the housing 2. As in Fig. 6 a) As shown, no projection is formed on the unthreaded section 26 of the housing 2 when the outer seal 3 is pushed 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 Fig. 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, this 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 shown in Fig. 6 b) can be seen. 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. Due to the notches 27, the outer diameter of the unthreaded section 26 is increased so that it is larger than the inner diameter D. R the outer seal 3 and this is arranged in a captive manner on the threadless section 26.

[0049] In Fig. Figure 6 c) shows the result of this assembly procedure. Due to the notches 27, part of the unthreaded section 26 is bent outwards, resulting in the projections 24 in these areas.

[0050] 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. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2012 207319 A1 [0002, 0004]

Claims

[1] 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 inside (20) and an outside (21), wherein on the outside (21) of the housing (2) a thread (22) with an outside diameter D T and a paragraph (25) with an outer diameter D A are designed wherein the housing (2) has a threadless section (26) with an outer diameter D between the thread (22) and the shoulder (25). U exhibits • the outer seal (3) has an inner diameter D R has and is located between the shoulder (25) and the thread (22) on the unthreaded section (26), characterized by, 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 by , that the projection (24) is formed around the outside of the housing (2) on the threadless section (26). [3] Housing (2) according to claim 1, characterized by , 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 any one of the preceding claims, characterized by,-that the housing (2) has an outer diameter D at the projection (24). H has, whereby D H greater than D U and D R and D T is. [5] Housing (2) according to any one of the preceding claims, characterized by , that the outer diameter of the outer seal (3) is greater than or equal to the outer diameter D A of the housing (2) at the paragraph (25). [6] having a spark plug, • a housing (2) with an outer seal (3) according to one of claims 1 to 5, • an insulator arranged inside the housing (2) • a central electrode arranged inside the insulator, • a ground electrode, • an ignition gap formed between the ground electrode and the center electrode. [7] Method for fitting an outer seal (3) to a spark plug housing (2) according to any one of claims 1 to 5, comprising the following steps: • Providing a spark plug housing (2) without an outer seal (3), wherein the thread (22) with an outer diameter of D is provided on the outside of the housing (2). T is trained • Providing an outer seal (3) with a chamfer (31) on its inner side, wherein the outer seal (3) has an inner diameter of D R has and D R greater than D T is, • 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), characterized by, that before the outer seal (3) is placed 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 the outer seal (3) is placed 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 by , that the projection (24) is formed after the outer seal (3) is placed, wherein the projection (24) is formed at least in a partial area of ​​the unthreaded section (26) in which a part of the housing material on the unthreaded section (26) is reshaped. [9] Method according to claim 7, characterized by, that prior to the placement of 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 D at the projection (24). H has and D H smaller than the outer diameter D R1 the outer seal (3) from the placement of the outer seal (3). [10] Method according to claim 9, characterized by , that after the outer seal (3) is placed, the outer seal (3) is deformed on its inner side (3b) at least in one section, so that the inner diameter D R the outer seal (3) at this section is reduced in size and the new inner diameter D R2 the outer seal (3) at this section is smaller than the outer diameter D H of the housing (2) at the projection (24), so that the projection (24) securely holds the outer seal (3). [11] Method according to claim 9, characterized by, that after the outer seal (3) is placed, the outer seal (3) is reshaped so that the outer seal (3) has a non-round shape, giving the outer seal (3) at least two different inner diameters D R1 , D R2 has an inner diameter D R1 is smaller than the second inner diameter D R2 and where D R1 smaller than D H , so that the projection (24) securely holds the outer seal (3). [12] Method according to claim 7, characterized by , that before the outer seal (3) is placed, the unthreaded section (26) already has one or more projections (24), wherein the housing (2) has an outer diameter D at the projection (24). H has and D H larger than the inner diameter D Rt1 the outer seal (3), and that for the placement of the outer seal (3) it is heated so that the inner diameter D Rt2the 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 D Rt1 the outer seal (3) smaller than the outer diameter D H of the housing (2) at the projection (24) and the projection (24) securely holds the outer seal (3).

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