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DE-102024210900-A1 - Spark plug housing with captive outer seal, spark plug and method for mounting the outer seal on the housing

DE102024210900A1DE 102024210900 A1DE102024210900 A1DE 102024210900A1DE-102024210900-A1

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 DT and a shoulder (25) with an outer diameter ADA are formed, wherein the housing (2) has a non-threaded section (26) with an outer diameter DU between the thread (22) and the shoulder (25).

Inventors

  • Thomas Steidten
  • Anatolij Odegov

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (12)

  1. Spark plug housing (2) with an outer seal (3), wherein the housing (2) has a longitudinal axis X and a longitudinal bore, giving the housing (2) an inner side (20) and an outer side (21), wherein a thread (22) with an outer diameter DT and a shoulder (25) with an outer diameter DA are formed on the outer side (21) of the housing (2), wherein the housing (2) has a non-threaded section (26) with an outer diameter DU between the thread (22) and the shoulder (25), and the outer seal (3) has an inner diameter RD and is arranged between the shoulder (25) and the thread (22) on the non-threaded section (26), characterized in 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 non-threaded section (26) which is configured to ensure that the outer seal (3) is securely attached to the housing (2). is.
  2. Housing (2) after 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) after Claim 1 , characterized in that the projection (24) is formed on a partial area of the threadless section (26) on the outside (21) of the housing (2) or that several projections (24) are formed on the threadless section (26) on the outside (21) of the housing (2), which are formed section by section along a circumference of the threadless section (26).
  4. Housing (2) according to one of the preceding claims, characterized in that the housing (2) has an outer diameter D H at the projection (24), wherein D H is larger than D U and D R and D T.
  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 D A of the housing (2) at the shoulder (25).
  6. comprising a spark plug, • a housing (2) with an external seal (3) after one of the Claims 1 until 5 , • an insulator arranged inside the housing (2) • a center 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 external seal (3) to a spark plug housing (2) according to one of the Claims 1 until 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 DT is formed on the outside of the housing (2), • Providing an outer seal (3) with a chamfer (31) on its inner side, wherein the outer seal (3) has an inner diameter of RD and RD is larger than DT , • Placing the outer seal (3) on the outside of the housing (2) on a threadless section (26) arranged between the thread (22) and a shoulder (25) of the housing (2), characterized in that, prior to placing the outer seal (3) on the outside of the housing (21), a projection (24) is formed on the threadless 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 threadless section (26) (26) a projection (24) is formed which is designed to hold the outer seal (3) securely on the housing (2).
  8. Procedure according to Claim 7 , characterized in that the projection (24) is formed after the outer seal (3) has been placed, wherein the projection (24) is formed at least in a partial area of the threadless section (26) in which a part of the housing material on the threadless section (26) is reshaped.
  9. Procedure according to Claim 7 , characterized in that , prior to the placement of the outer seal (3), the threadless section (26) of the housing (2) has a projection (24) or several projections (24), wherein the housing (2) at the projection (24) has an outer diameter D H and D H is smaller than the outer diameter D R1 of the outer seal (3) from the placement of the outer seal (3).
  10. Procedure according to Claim 9 , characterized in that after the outer seal (3) is placed, the outer seal (3) is reshaped on its inner side (3b) at least in one section, so that the inner diameter D R of the outer seal (3) is reduced in this section and the new inner diameter D R2 of the outer seal (3) in this section is smaller than the outer diameter D H of the housing (2) at the projection (24), so that the projection (24) holds the outer seal (3) securely.
  11. Procedure according to Claim 9 , characterized in 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, whereby the outer seal (3) has at least two different inner diameters D R1 , D R2 , wherein one inner diameter D R1 is smaller than the second inner diameter D R2 and wherein D R1 is smaller than D H , so that the projection (24) holds the outer seal (3) securely.
  12. Procedure 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) at the projection (24) has an outer diameter D H and D H is larger than the inner diameter D Rt1 of the outer seal (3), and in that, for the placement of the outer seal (3), it is heated so that the inner diameter D Rt2 of the outer seal (3) increases and the outer seal (3) can be pushed over the projection (24), wherein, after the placement of the outer seal (3), it cools down again so that the inner diameter D Rt1 of the outer seal (3) is 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).

Description

State of the art The present invention relates to a spark plug housing with an outer seal which is arranged to prevent loss on the housing, as well as a spark plug with the housing and the outer seal arranged to prevent loss, and a mounting method for the outer seal on the housing. Spark plugs have a housing and an outer seal on its exterior. The main function of the outer seal is to seal the surface 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 in a captive manner, 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 manufacturing process is described in the... DE 10 2012 207319 A1 The process is revealed. First, the outer seal is positioned on 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, so the thread prevents the outer seal from being lost. However, the outer seal can become misaligned with one thread turn, which could damage the thread. 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. 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. Regarding the spark plug and its manufacturing process according to the DE 10 2012 207319 A1 This is not possible. 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 This problem is solved by the spark plug housing according to the invention and the claimed assembly method. 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 RD 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. 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. 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. 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, which ensures that The outer seal has a shorter length on its inner side than its maximum length measured parallel to the longitudinal axis of the housing. The inner surface of the outer gasket is framed by the unthreaded section and its projection. The projection extends into the volume not filled by the outer gasket 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 gasket such that when the outer gasket rests against the sealing surface of the shoulder, the proj