Improved contact surface for a spark plug boot

Abstract

The invention relates to a spark plug jacket, for example for large or high-performance internal combustion engines, and to a corresponding method for manufacturing a spark plug jacket, in particular providing an improved sealing of a coolant chamber. Accordingly, a spark plug jacket (10) is proposed comprising a contact surface (12) for contacting a support surface of a cylinder head of an internal combustion engine, wherein in a first state, when a spark plug is not mounted in the spark plug jacket (10), at least a portion of the contact surface (12) of the spark plug jacket (10) defines a first angular offset with respect to a contact surface direction defined by the support surface of the cylinder head, and in a second state, when the spark plug is mounted to the spark plug jacket (10), said portion defines a second angular offset, wherein the first angular offset is greater than the second angular offset.

Description

Technical Field

[0001] The present invention relates to a spark plug sleeve, for example for a large or high-performance internal combustion engine, and a corresponding method for manufacturing the spark plug sleeve, particularly providing an improved seal for the coolant chamber. Background Technology

[0002] In internal combustion engines, the cylinder head is typically configured to receive spark plugs to ignite the combustible mixture within the combustion chamber. The heat generated by the operation of the spark plugs and the corresponding combustion causes a localized rise in temperature of the spark plugs and surrounding components, which can be harmful. Therefore, the temperature needs to be maintained within a predetermined range and thus cooled. This cooling is provided by a coolant, which may circulate in a coolant circuit and reside in one or more chambers adjacent to the spark plugs.

[0003] Direct contact between the coolant and the spark plug necessitates draining or replacing the coolant each time the spark plug is replaced or overhauled. To avoid this draining, which can be laborious and expensive, and may require waiting time to allow the coolant to reach an acceptable temperature range, a spark plug sleeve is installed in the cylinder head. This sleeve is configured to screw into the corresponding threads of the cylinder head and also includes threads to receive the spark plug within the sleeve. Therefore, the spark plug sleeve seals the coolant chamber and remains in place during spark plug replacement, facilitating the process.

[0004] However, when the spark plug is installed into the spark plug bushing after the spark plug bushing has been installed into the cylinder head, this can cause a reduction in pressure or bolt force between the spark plug bushing and the cylinder head. Due to the limited available clamping length, this reduction in pressure or bolt force can lead to leakage toward the coolant chamber, allowing combustion gases to permeate the coolant through the spark plug bushing.

[0005] Therefore, it is necessary to improve the sealing of the spark plug sheath toward the cylinder head and at least partially eliminate the aforementioned adverse conditions. Summary of the Invention

[0006] Based on existing technology, the object of this invention is to provide a novel and inventive spark plug sleeve for internal combustion engines. In particular, its object is to improve the sealing properties of the spark plug sleeve and / or prevent leakage, even after spark plug replacement.

[0007] This objective is achieved by a spark plug having the features of claim 1 and a method of manufacturing a spark plug having the features of claim 10. Preferred embodiments are set forth in this specification, the accompanying drawings, and the dependent claims.

[0008] Therefore, a spark plug sleeve is proposed, comprising a contact surface for contacting a support surface of a cylinder head of an internal combustion engine, wherein in a first state, when the spark plug is not installed in the spark plug sleeve, at least a portion of the contact surface of the spark plug sleeve defines a first angular offset relative to a contact surface direction defined by the support surface of the cylinder head. In a second state, when the spark plug is installed in the spark plug sleeve, said portion defines a second angular offset, wherein the first angular offset is greater than the second angular offset.

[0009] In addition, a method for manufacturing spark plug sheaths is proposed, which includes the following steps:

[0010] - Install spark plug sleeves that limit the longitudinal direction;

[0011] - Screw the biasing element into the threads of the spark plug sleeve, which are configured to accommodate the spark plug's threads; and

[0012] - In the installation state of the bias element, modify at least a portion of the contact surface of the spark plug sheath to contact the support surface of the cylinder head of the internal combustion engine. Attached Figure Description

[0013] The invention will be more readily understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0014] Figure 1 The longitudinal section of the lower region of the spark plug sheath is shown in the uninstalled and spark plug-free states.

[0015] Figure 2 The diagram shows the mounting of the bias element according to... Figure 1 Spark plug sleeve;

[0016] Figure 3 The diagram illustrates the modification of the contact surface in the mounting state of the bias element, based on... Figure 2 Spark plug sheaths; and

[0017] Figure 4 The following is shown after removing the bias element. Figure 3 Spark plug sheath. Detailed Implementation

[0018] The invention will be explained in more detail below with reference to the accompanying drawings. In the drawings, the same elements are indicated by the same reference numerals, and repeated descriptions may be omitted to avoid redundancy.

[0019] exist Figure 1In the diagram, a longitudinal section of the lower region of the spark plug sleeve 10 is schematically shown in both an uninstalled state and a spark plug-free state. This region corresponds to the combustion zone of the cylinder head in the installed state of the spark plug sleeve 10 facing the cylinder head. The spark plug sleeve 10 includes a contact surface 12 for contacting a support surface of the internal combustion engine cylinder head. The contact surface 12 extends from an inner diameter 14 to an outer diameter 16 defined by the contact surface, wherein a selectable curvature is provided at the inner diameter 14 connecting the end section of the spark plug sleeve 10 extending longitudinally. A chamfer or bevel is provided at the outer diameter 16, which connects the contact surface 12 to the upper portion of the spark plug sleeve 10 extending away from the combustion zone. An external thread 18 is used to install the spark plug sleeve into the cylinder head, and an internal thread 20 is used for threaded engagement with the spark plug.

[0020] The contact surface 12 is described as a substantially flat and / or planar surface extending in the radial direction, i.e., perpendicular to the longitudinal axis of the spark plug sleeve 10. When the spark plug sleeve 10 is installed, in its original, unmodified state, the entire contact surface 12 will contact the support surface of the cylinder head. After the spark plug sleeve 10 is installed, the installation of the spark plug therein can provide undesirable deformation of the spark plug sleeve 10, which can impair the spark plug installation and also cause undesirable pressure distribution between the spark plug sleeve 10 and the cylinder head, potentially leading to leakage between the spark plug sleeve 10 and the cylinder head.

[0021] To improve pressure distribution and prevent this leakage, such as Figure 2 As shown, the biasing element 22 is mounted in the spark plug sleeve 10 and engages its internal thread 20. In this mounted state of the biasing element 22, the contact surface 12 is deformed and a portion of the contact surface 12 at the inner diameter 14 protrudes longitudinally toward the bottom end of the spark plug sleeve 10. Therefore, a longitudinal offset 24 is provided between the inner diameter 14 and the outer diameter 16, as indicated by the dashed line and the corresponding double arrow.

[0022] The biasing element 22 is formed as a dummy spark plug, which may not have the corresponding function of a spark plug, but may have substantially the same shape and size, and may be formed, for example, of a solid material (e.g., steel) to withstand greater torque without compromising the structural integrity of the dummy spark plug. According to this non-limiting embodiment, an installation torque of approximately 200 Nm has been applied to the dummy spark plug. Therefore, the protrusion of the contact surface 12 in the longitudinal direction at the inner diameter 14 may not exactly correspond to the protrusion obtained when installing a normally used spark plug, which can be installed at, for example, 30 Nm to 50 Nm. However, as... Figure 3 and 4 As shown, the additional torque and corresponding longitudinal offset 24 may be advantageous for modification, since it can be ensured that this condition can be effectively avoided by modifying the contact surface 12.

[0023] Therefore, as Figure 3 As shown, the material has been removed; that is, in the installed state of the bias element 22, the material of the protruding portion has been removed. Therefore, the contact surface 12 has been flattened and extends substantially radially from the inner diameter 14 to the outer diameter 16. By providing this flattening, an optimal contact interface is ensured between the spark plug sleeve 10 and the cylinder head without compromising the installation of the spark plug sleeve 10 and the spark plug, and with improved pressure distribution.

[0024] Furthermore, if a lower torque is applied during spark plug installation compared to the installation torque of the bias element 22, an angular offset can be provided relative to the radial direction and / or support surface of the cylinder head in the installed state of the spark plug sleeve 10. That is, a (slight) inclination of the contact surface 12 can be provided in a radially inward direction starting from the outer diameter 16 or at a point radially inward from the outer diameter 16, while maintaining contact between the portion of the contact surface 12 at the outer diameter 16 and the support surface of the cylinder head.

[0025] Furthermore, the modification of the contact surface 12, namely the removal of material from a portion of the contact surface 12, results in an angular offset of the contact surface 12 relative to the radial or extending direction of the spark plug sleeve 10 and / or the extending direction of the cylinder head support surface (i.e., as seen in the intended installation state) in the uninstalled or loose state of the spark plug sleeve 10, i.e., where no spark plug is installed in the spark plug sleeve 10. As shown, the modification of the contact surface 12 under pressure, i.e., using the installed biasing element, can thus provide a contact surface 12 formed as a generally (asymmetrical) conical shape, wherein the apex points generally downward in the longitudinal direction, which can correspond to the position of the cylinder head support surface in the installation state.

[0026] Furthermore, the conical shape is radially offset towards the outer diameter 16. This circumferential contact at this end is particularly advantageous for providing a more flexible connection and a more favorable pressure distribution. When installing the spark plug and applying the appropriate installation torque, the contact surface 12 can again be oriented towards… Figure 3 The state shown is partially deformed. As a result, the angular offset set in the spark plug sleeve 10 when no spark plug is installed can be reduced again when the spark plug is installed, so that the contact interface can be expanded in the radially inward direction according to the applied installation torque.

[0027] according to Figure 4 The modified longitudinal offset 24 of the spark plug sleeve 10 can advantageously correspond to the following: Figure 2 The longitudinal offset of the unmodified spark plug sleeve 10 is biased. When the spark plug is subsequently installed into the spark plug sleeve 10, the longitudinal offset 10 can be reduced again in response to the reduced angular offset and the applied installation torque.

[0028] It will be apparent to those skilled in the art that these embodiments and items merely describe examples with a wide range of possibilities. Therefore, the embodiments shown herein should not be construed as limiting these features and configurations. Any possible combination and configuration of the features can be selected according to the scope of the invention.

[0029] This is particularly relevant to the case of the following optional features, which can be combined with some or all of the previously mentioned embodiments, items and / or features in any technically feasible combination.

[0030] A spark plug sheath is provided.

[0031] Such a spark plug sleeve may include a contact surface for contacting a support surface of a cylinder head of an internal combustion engine, wherein in a first state, when the spark plug is not installed in the spark plug sleeve, at least a portion of the contact surface of the spark plug sleeve defines a first angular offset relative to the contact surface direction defined by the support surface of the cylinder head, and in a second state, when the spark plug is installed in the spark plug sleeve, said portion defines a second angular offset, wherein the first angular offset is greater than the second angular offset.

[0032] The advantage of a larger angular offset of the spark plug in the uninstalled state is that the contact surface can contact a predetermined area of ​​the cylinder head's support surface before the installation torque of the spark plug, housed within the spark plug sleeve, is applied. For example, an initial (circumferential) line contact can be provided, which can extend, i.e., expand, in the direction of the main contact surface defined by the cylinder head's support surface when the predetermined installation torque is applied.

[0033] In other words, when installing the spark plug into the spark plug bushing, the contact area or interface between the spark plug bushing and the cylinder head can be increased, so that the initial longitudinal distance or angle between the contact surface and the support surface gradually decreases when a predetermined torque is applied. This provides a more flexible connection, which is advantageous for pressure distribution between the spark plug bushing and the cylinder head. In particular, it can effectively counteract losses of bolt load and / or pressure caused, for example, by surface roughness reduction and / or by temperature deformation during spark plug bushing installation, and thus prevent leakage between the spark plug bushing and the cylinder head.

[0034] This flexible connection also facilitates the insertion and installation of the spark plug bushing because, before and after applying the predetermined installation torque, a gradually increasing contact interface can be provided between the spark plug bushing (its contact surface) and the cylinder head, rather than a substantially fixed and parallel contact interface. In other words, the flexible connection makes the contact surface more suitable for support during spark plug bushing installation. Therefore, improved spark plug bushing installation and corresponding bolt force can be provided to effectively prevent leakage between the spark plug bushing and the cylinder head. This bolt force can be further increased when the spark plug is installed into the spark plug bushing after the spark plug bushing has been installed into the cylinder head, as this further improves the connection between the spark plug bushing and the cylinder head through a correspondingly modified angular offset of the contact surface of the spark plug bushing.

[0035] The contact surfaces, particularly the first and / or second angular offsets, can be adapted to the application, i.e., the intended support surfaces of the cylinder head. Therefore, the contact surfaces of the spark plug bushing can be configured according to various first and second angular offsets. For example, for an axially symmetrical spark plug bushing, the radial direction of the spark plug bushing can substantially correspond to the direction defined by the support surfaces of the cylinder head, such that the first and second angular offsets can correspond to corresponding offsets in the radial direction of the spark plug bushing. However, the geometry and dimensions of the support surfaces of the cylinder head can vary between different types of cylinder heads, such that the radial direction and principal direction defined by the support surfaces do not necessarily need to correspond.

[0036] Preferably, the radial extension of the spark plug sheath substantially corresponds to the main lateral direction of the cylinder head or the main extension direction of the support surface of the cylinder head. In this way, the first and second angular offsets can correspond to corresponding offsets with respect to the radial extension of the spark plug sheath, i.e., in the uninstalled and installed states of the spark plug within the spark plug sheath.

[0037] To provide a (further) gradual increase in the contact interface and thus a more uniform pressure distribution during the application of the spark plug installation torque, essentially the entire contact surface can include an angular offset relative to the radial direction of the spark plug sheath in the uninstalled state. Therefore, the contact surface can include, for example, one or more angular offsets for different portions to form a predetermined geometry and / or one or more edges.

[0038] Preferably, the angular offset across the entire contact surface is continuous and corresponds to a first angular offset across the entire contact surface. Therefore, the contact surface can be provided by a substantially straight surface that can be inclined or angled relative to the radial direction of the cylinder head support surface and / or the spark plug sheath, i.e., forming an (imaginary) intersection line with it. Considering the pressure distribution during the application of the installation torque for the spark plug and the flexibility to provide further improved connection, continuous angular offset can also be further advantageous when installing the spark plug sheath.

[0039] This portion of the contact surface may define an outer diameter and an inner diameter, wherein the contact surface includes a longitudinal offset between the inner and outer diameters. Preferably, the entire contact surface defines or extends between the inner and outer diameters. Thus, the longitudinal offset can provide a longitudinal extension of the contact surface, such that, for example, in the installed state of a spark plug sheath, the end of the contact surface at the outer diameter is closer to the end of the spark plug sheath adjacent to the combustion zone of the cylinder head.

[0040] Although this configuration can also be reversed, with the end of the contact surface at the inner diameter closer to the combustion zone in the installed state of the spark plug sheath, the longitudinal extension at the outer diameter has the advantage that, depending on the configuration of the cylinder head and its supporting surfaces, the initial contact interface between the spark plug sheath and the cylinder head can be set at the outer diameter, thereby providing improved connection flexibility that is favorable to the (subsequent) pressure distribution.

[0041] Preferably, the longitudinal offset is between 1 and 30 micrometers, more preferably between 5 and 15 micrometers, and particularly between 8 and 12 micrometers. This offset can, for example, selectively achieve a predetermined linear pressure, which can be advantageously provided by a first angular offset. It has been found that a longitudinal offset between 8 and 12 micrometers is particularly advantageous in order to provide sufficient linear pressure without potentially adversely affecting the sealing function.

[0042] To further enhance this linear pressure, the portion of the contact surface preferably comprises a conical shape, preferably in the longitudinal direction defined by the spark plug sheath.

[0043] The portion of the contact surface having a first angular offset may, for example, form a lateral extension or "leg" in the shape of a cone, and the end of said portion may include a bevel or chamfer forming a second adjacent lateral extension or "leg," such that an edge is formed that can provide initial contact with the support surface of the cylinder head.

[0044] Furthermore, the conical shape is preferably asymmetrical, particularly in the radial direction of the spark plug sleeve. The conical shape can be configured to face the combustion zone of the cylinder head in the installed state of the spark plug sleeve.

[0045] For example, the entire contact surface may extend from the inner diameter toward the outer diameter defined by the contact surface, and may include a bevel or chamfer at the end of the contact surface at the outer diameter. The contact surface preferably includes a greater radial extension than the radial extension of the bevel or chamfer, to form an asymmetrical conical shape, wherein the tip or apex of the cone shape faces the outer diameter and is offset toward the end of the spark plug sheath facing the combustion zone in the installed state of the spark plug sheath. The bevel or chamfer may also include a longitudinal offset relative to the outer wall of the spark plug sheath, which may correspond to a longitudinal offset between the inner and outer diameters of the contact surface.

[0046] Although the apex of the cone shape can advantageously be oriented parallel to the axis of symmetry of the spark plug sheath, the apex can also be set at an angle to it, which is advantageous for a particular embodiment of the cylinder head and the corresponding support surface, and this can, for example, depend on the corresponding application of the spark plug sheath.

[0047] In addition, a method for manufacturing spark plug sheaths is provided.

[0048] This method may include the following steps:

[0049] - Install spark plug sleeves that limit the longitudinal direction;

[0050] - Screw the biasing element into the threads of the spark plug sleeve, which are configured to accommodate the spark plug's threads; and

[0051] - In the installation state of the bias element, modify at least a portion of the contact surface of the spark plug sheath to contact the support surface of the cylinder head of the internal combustion engine.

[0052] By mounting a biasing element within the spark plug sleeve, the configuration of the contact surface can be altered in the biased state of the spark plug sleeve. This significantly facilitates partial modification of the contact surface by enabling direct modification of a portion of the contact surface or removal of excess portions of the contact surface in the biased state. In particular, modifications within a specific range, such as those in the range of 5 to 50 micrometers, can be performed in this manner (potentially manually) much faster than modifications, such as those controlled by computer numerical control, which might otherwise require considerable time to achieve the desired level of accuracy.

[0053] By modifying the bias state of the spark plug sheath, the contact surface can be adapted to a desired state in the state where the spark plug sheath receives and accommodates the corresponding element. For example, the bias state can be similar to the state and / or shape of the spark plug sheath in the cylinder head in the installed state, and have a spark plug installed therein. Therefore, the ideal state of the contact surface can be directly obtained by appropriately modifying at least a portion of the contact surface in the bias state.

[0054] For example, the biasing element can be installed with an installation torque of at least 30 Nm or at least 50 Nm, which may correspond to the installation torque of commonly used spark plugs. However, the biasing element is preferably installed with a predetermined installation torque that may not be compatible with commonly used spark plugs, for example, at least 100 Nm or between 150 Nm and 250 Nm, such as approximately 200 Nm. This ensures that optimal conditions are not fully achieved when the biasing element is subsequently removed, the spark plug bushing is installed in the cylinder head, and the spark plug is installed in the spark plug bushing. In other words, this provides predetermined tolerances or clearances and ensures that the application of the installation torque and the complete retention of the spark plug are not offset by increased torque resistance due to the shape of the contact surfaces.

[0055] In order to apply a larger torque, such as 100 Nm or 200 Nm, the biasing element can be formed as a dummy spark plug. The dummy spark plug may not have the corresponding functionality, but may have substantially the same shape and size, and may be formed, for example, from a solid material so as to withstand the larger torque without compromising the structural integrity of the dummy spark plug.

[0056] Preferably, the modification step includes removing a portion of the material from the contact surface to flatten the contact surface in the mounted state of the biasing element, preferably obtaining a substantially planar portion extending in a substantially radial direction in the mounted state of the biasing element.

[0057] Furthermore, the portion of the contact surface from which material is removed preferably corresponds to a portion of the contact surface that, in the mounted state of the biasing element, has an angular offset relative to the spark plug sheath in the radial direction and / or extends in the longitudinal direction. In other words, a portion of the contact surface may be removed, protruding from the radial and / or planar surface in the longitudinal direction.

[0058] Thus, the specific predetermined shape of the spark plug sheath can be achieved when the biasing element is subsequently removed. For example, such specific removal or flattening of a portion of the contact surface can allow a portion or the entire contact surface to include an angular offset relative to the radial direction of the spark plug sheath in the off-mounted state of the biasing element. This angular offset can be substantially continuous from the inner diameter toward the outer diameter defined by the contact surface, wherein a bevel or chamfer can be provided, for example, at the end of the outer diameter of the contact surface. A longitudinal offset can be provided between the inner and outer diameters to form a substantially conical shape that can be offset radially toward the outer diameter and can include a apex at the end of the spark plug sheath facing the adjacent combustion zone in the mounted state of the spark plug sheath in the cylinder head.

[0059] Therefore, this method can provide a circumferential apex or edge on the outer diameter of the contact surface. As mentioned above, this is particularly advantageous when installing spark plug sheaths into the cylinder head, providing circumferential contact with the cylinder head's support surface at the outer diameter of both the support and contact surfaces, i.e., providing a more flexible connection.

[0060] The modification steps may include removing material from the portion by machining or milling under stress.

[0061] Alternatively, the modification step may include removing the material from the portion by insert turning. Preferably, material removal is provided by compression, preferably using the entire width of the cutting edge. This can provide a more uniform modification. More preferably, a predetermined compressive force may be applied continuously, wherein the compressive force is preferably monitored and / or controlled to avoid Brinell indentations or chatter marks.

[0062] Various spark plug sleeves can be manufactured according to the above method. Preferably, the method for manufacturing spark plug sleeves can be performed to manufacture spark plug sleeves according to the invention. Therefore, the corresponding features and technical advantages described in consideration of spark plug sleeves are equally applicable to the method according to the invention, and vice versa where applicable, and thus reference is made to the above to avoid redundancy.

[0063] Although the term "threaded connection" has been used above, it should be understood that more general fastening methods may be used where applicable, such as securing or mounting a biasing element in a spark plug sleeve. Preferably, the term "screw-in" indicates rotational or rotary motion that provides longitudinal displacement, for example, by applying torque.

[0064] Industrial applicability

[0065] Referring to the accompanying drawings, a spark plug sleeve for an internal combustion engine cylinder head and a method for manufacturing the spark plug sleeve are presented. The aforementioned spark plug sleeve can be applied to various engines, such as (large) gas turbine engines, which require an ignition system and its cooling, and in which spark plugs may need to be replaced. The spark plug sleeve and its corresponding contact surface improve the bolt force of the spark plug sleeve, thereby preventing combustion gases from leaking into the coolant chamber even after repeated spark plug replacements. Furthermore, the spark plug sleeve can be applied as part of a replacement or modification, wherein the spark plug sleeve can be replaced, for example, during maintenance or before engine use and operation.

Claims

1. A spark plug sleeve (10) including a contact surface (12) for contacting a support surface of a cylinder head of an internal combustion engine, wherein in a first state, when a spark plug is not installed in the spark plug sleeve (10), at least a portion of the contact surface (12) of the spark plug sleeve (10) defines a first angular offset relative to a contact surface direction defined by the support surface of the cylinder head, and in a second state, when the spark plug is installed on the spark plug sleeve (10), the portion defines a second angular offset relative to the contact surface direction defined by the support surface of the cylinder head, wherein the first angular offset is greater than the second angular offset.

2. The spark plug sleeve (10) according to claim 1, wherein in the uninstalled state, substantially the entire contact surface (12) has an angular offset relative to the radial direction of the spark plug sleeve (10).

3. The spark plug sheath (10) according to claim 2, wherein the angular offset is continuous and corresponds to the first angular offset of the entire contact surface (12).

4. The spark plug sheath (10) according to any one of claims 1 to 3, wherein the portion of the contact surface (12) defines an outer diameter (16) and an inner diameter (14), and wherein the contact surface (12) includes a longitudinal offset (24) between the inner diameter (14) and the outer diameter (16).

5. The spark plug sheath (10) according to claim 4, wherein the longitudinal offset (24) is between 1 and 30 micrometers.

6. The spark plug sheath (10) according to claim 5, wherein the longitudinal offset (24) is between 5 and 15 micrometers.

7. The spark plug sheath (10) according to claim 5, wherein the longitudinal offset (24) is between 8 and 12 micrometers.

8. The spark plug sleeve (10) according to any one of claims 1 to 3, wherein the portion comprises a conical shape in the longitudinal direction defined by the spark plug sleeve (10).

9. The spark plug sleeve (10) according to claim 8, wherein the conical shape is asymmetrical in the radial direction of the spark plug sleeve (10).

10. The spark plug sleeve (10) according to claim 8, wherein the conical shape is configured to face the combustion zone of the cylinder head in the installed state of the spark plug sleeve (10).

11. The spark plug sleeve (10) according to any one of claims 1 to 3, wherein the radial extension of the spark plug sleeve (10) substantially corresponds to the main lateral direction of the cylinder head.

12. A method for manufacturing a spark plug sheath (10), comprising the following steps: - Set the spark plug sleeve (10) to limit the longitudinal direction; - Screw the biasing element (22) into the threads (20) of the spark plug sleeve (10) configured to accommodate the spark plug; as well as - In the installed state of the biasing element (22), at least a portion of the contact surface (12) of the spark plug sleeve (10), the contact surface being used to contact the support surface of the cylinder head of the internal combustion engine, is modified. The modification steps include removing a portion of the material from the contact surface (12) so that the contact surface (12) is flattened in the mounting state of the biasing element (22).

13. The method of claim 12, wherein the modification step obtains a substantially planar portion of the contact surface (12) extending in a substantially radial direction in the mounting state of the biasing element (22).

14. The method according to claim 12, wherein the portion of the contact surface (12) from which material is removed corresponds to the portion of the contact surface (12) in the mounting state of the biasing element (22) that has an angular offset from the radial direction of the spark plug sheath (10) and / or extends along the longitudinal direction.

15. The method according to any one of claims 12 to 14, wherein the modification step comprises removing material from the portion by machining or milling under stress.

16. The method according to any one of claims 12 to 14, wherein the modification step includes removing material from the portion by insert turning.

17. The method of claim 16, wherein material removal is provided by compression using the entire width of the cutting edge.

18. The method of claim 17, wherein a predetermined compressive force is continuously applied, and the compressive force is monitored and / or controlled.

19. The method according to any one of claims 12 to 14, wherein the method is used to manufacture the spark plug sheath (10) according to any one of claims 1 to 11.

Images