SCREW CONNECTION

Abstract

In order to prevent gap corrosion at a freely accessible face of a threaded connection (1) in particular when used in sea water the threaded connection (1) is encapsulated in a circumferential tight annular chamber (3) in order to prevent a penetration of sea water to the threaded connection (1) and thus prevent the gap corrosion between the two threads (2, b) of the threaded connection (1) meshing with each other. This is achieved by a particularly pressure tight and long service life primary seal (6) and advantageously a supplemental secondary seal (16), in particular for a threaded connection (1) which seals a cable pass through (15) of a housing (22).

Claims

1. An encapsulated threaded connection (1), comprising: at least two annular components (A, B) to be threaded into each other and made from metal or synthetic material, wherein a respective thread of two threads (2a, b) of the threaded connection (1) is respectively arranged at each of the components, characterized in that the threads (2a, b) are received in an annular chamber (3) that is sealed tight in an outward direction towards the ambient (100), the walls (4a-d) of the chamber (3) are at least partially formed by the components (A, B), and the adjacent walls (4a, b) of the chamber (3) formed by the components (A, B) are sealed relative to each other by at least one respective annular primary seal (6).

2. The threaded connection (1) according to claim 1, characterized in that the primary seal (6), is either arranged in the axial direction (10), the threading direction (10) between the two adjacent walls (4a, b) formed in particular by the components (A, B) and is made from an elastic seal material, in particular an elastic seal element (7), or is made from a sealing compound (8) either formed in the seal gap (9) between the adjacent walls (4a, b) formed in particular by the components (A, B) or from a sealing compound (8) covering the outer seal gap (9), or is made from a welt seam (18) or a glued seam.

3. The threaded connection (1) according to claim 1, characterized in that the adjacent walls (4a, b) that are formed in particular by the components (A, B) are sealed relative to each other in addition to the first primary seal (6) by an additional primary seal (6) or by an annular secondary seal (16).

4. The threaded connection (1) according to claim 3, characterized in that the secondary seal (16) is made from an elastic seal material, a seal element (7) that is pressure loaded in one or in all transversal directions (11, 12) when the threaded connection (1) is closed.

5. The threaded connection (1) according to claim 3, characterized in that the secondary seal (16) is made from a radial circumferential O-ring seal (13) which is arranged between two components (A, B) that are movable relative to each other in the axial direction (10) and wherein the secondary seal is only compressed radially.

6. The threaded connection (1) according to claim 1, characterized in that one of the components (A) is a threaded sleeve (20), having a screw top (21).

7. The threaded connection (1) according to claim 1, characterized in that the threaded connection (1) includes a cable pass through (15) and a cable section (5′) of the cable (5) that is run through the cable pass through (15) is sealed relative to one of the walls (4a-d) of the chamber (3).

8. The threaded connection (1) according to claim 7, characterized in that the cable pass through (15) includes two pass through openings (15a, b) for the cable (5) that are aligned with each other in the axial direction, wherein at least one pass through opening, in particular both pass through openings are arranged in a wall (4a, b) defining the chamber (3).

9. The threaded connection (1) according to claim 1, characterized in that one respective wall of the walls (4c, d) of the chamber (3) is formed by one of the primary seals (6), in particular a seal element (7).

10. The threaded connection (1) according to claim 9, characterized in that the seal element (7) is a seal sleeve (7′) in which a pass through opening (15a) for the cable (5) is arranged.

11. The threaded connection (1) according to claim 10, characterized in that the seal sleeve (7′) has a cross section whose outer contour tapers cone shaped in at least one of the axial directions (10) towards the face end, and the contact surface for the seal sleeve (7′) is accordingly configured at one of the components (A, B).

12. The threaded connection (1) according to claim 1, characterized in that at least one secondary seal (16), being an additional primary seal (6) arranged between the threaded connection (1) and the face side primary seal (6).

13. The threaded connection (1) according to claim 1, characterized in that the threaded connection (1) is made from plural pairs of meshing threads (2a, b, 2′a, b) arranged behind one another in the axial direction (10).

14. The threaded connection (1) according to claim 1, characterized in that the pairs of threads (2a, b, 2, b) between the same two components (A, B) are respectively arranged in a separate chamber (3, 3″) sealed relative to each other by a secondary seal (16), or by a primary seal (6).

Description

c) Embodiments

[0035] Embodiments of the invention are subsequently described in more detail with drawing figures, wherein:

[0036] FIG. 1a, b illustrates a threaded connection according to the invention in an axial sectional view and in a cross sectional view;

[0037] FIG. 2a, b illustrates an electronic housing, in particular a sensor housing with a threaded connection according to the invention in an exploded view;

[0038] FIG. 2b illustrates the housing of FIG. 2a in an assembled condition in top view;

[0039] FIG. 3a, b illustrates the cable inlet into the housing of FIG. 2a, b with the threaded connection cut in an axial direction of the cable inlet in different blown up scales;

[0040] FIG. 3c illustrates another engineering application of the O-ring seal;

[0041] FIG. 4 illustrates a threaded connection according to the invention with two threads arranged in axial sequence in an axial sectional view.

[0042] FIG. 1a illustrates the typical situation of 2 components A, B of a threaded connection 1 that are to be threaded together in this case of a housing 22 with an inner cavity configured as component A which includes a threaded spout 2′ that protrudes in an outward direction, advantageously rotation symmetrical. This threaded spout 22′ includes an inner pass through opening extending in an axial direction of the threaded spout 22′, wherein the pass through opening establishes a connection from the interior space of the housing to the outer ambient 100 wherein the connection shall be close able using a screw cap 21 forming the component B that is, wherein the screw cap is threaded onto an outer circumference of the threaded spout 22′ that shall be closeable tight.

[0043] When the outer ambient 100 about the housing 22 is made from an aggressive medium like sea water it is important for a long service life of the threaded connection and thus of the components typically electronic components arranged in the interior of the housing 22 that the medium of the ambient 100 cannot get to the threaded connection 1 even over long time periods and cannot cause any gap corrosion at this location wherein the gap corrosion can damage the threaded connection 1 over a short time period and can also destroy it completely.

[0044] For this purpose the typically annular threaded connection 1 is received in a chamber 3 that is also configured annular in a threaded condition of the two components A, B in an outward direction wherein the chamber 3 is in particular tight towards the ambient 100.

[0045] The annular, in particular rotation symmetrical configuration of the threaded connection 1 and at least in the portion of the threaded connection 1 of the components A, B threaded together, herein of the threaded spout 22′ and of the screw cap 21 can be derived from the cross sectional representation of FIG. 1b, in particular the meshing threads 2a, b of the threaded connection 1.

[0046] The walls of the annular chamber 3 are partially formed by the components A, B, themselves partially by other components.

[0047] The radially inner circumferential surface of the chamber 3 is formed in this case by the outer surface of the threaded spout 22, the radially outer circumferential surface of the chamber 3 from the inner circumferential surface of the screw cap 21.

[0048] The right annular face surface in FIG. 1a is formed by one of the two primary seals 6 of the threaded connection 1 which is made in this case from a form stable seal element 7 made from elastic material, thus provided as a seal plug 7′″. The seal plug 7′″ has an approximately conical or convex cambered cross section of an outer circumference and protrudes with a portion of its greatest diameter radially outward into the axial gap between the free face of the housing spout 22′ and the base of the screw cap 21.

[0049] When tightening the threaded connection 1 the seal plug 7′″ is compressed there between in the axial direction. Due to the conical cross section of the outer circumference and/or a corresponding conical inner circumference of the housing spout 22′ at its free front end into which the sealing plug 7′″ protrudes the sealing plug 7′″ is compressed by axial force loading, not only in the axial direction, but also by the conical shaped of the inner circumference of the housing spout 22′ as well as of the outer circumference of the seal plug 7′″ also causes a radial compression.

[0050] Since advantageously also the transition from the base to the inner circumferential walls of the screw cap 21 is slanted towards the axial direction or rounded, also this bevel or round shape compresses the threaded plug 7′″ in radial direction when threading the threaded cap 21 axially forward.

[0051] This way the seal plug 7′″ made from elastic material is preloaded in the radial direction and also in the axial direction and maintains its sealing properties also e.g. under temperature induced size variations of the screw cap 21 as well as of the threaded spout 22′ so that a face side ring wall 4c of the chamber 3 is reliably provided.

[0052] The other face side ring surface 4d of the chamber 3 is formed in that the free face of the dust cap 21 is directly or indirectly sealed against a radially extending outer surface of the housing 22 and this location has to be permanently sealed by a second primary seal 6 with increasing threading of the threaded connection 1, thus of the screw cap 21 against the housing 22, the screw cap 21 after the primary seal 6 configured as a sealing plug 7′″ is already sufficiently preloaded and sized accordingly. Thus the radially extending outer surface of the housing 22 extends from a transition of the base of the housing spout 22′ with respect to the radial direction of the screw connection 1 radially further outward.

[0053] For this function plural options are available.

[0054] As illustrated in FIG. 1a in the lower half the primary seal 6 can be configured as a seal ring 7′ which is inserted between both surfaces before the dust cap 21 is threaded on and which is axially compressed further when the threaded connection 1 is tightened.

[0055] Instead of a form stable seal element 7 this can also be a curable or partially curable sealing compound 8 which is introduced into the seal gap 9 before the threaded cap 21 is screwed down.

[0056] This sealing compound 8 can also be a glue.

[0057] As evident from the upper half of the figure the screw cap 21 configured as component B can be moved with its face until it directly contacts the outer surface of the housing 2, the component A either contacting or with a small distance and then the two components A, B, thus the free face of the screw cap 21 can be welded with the outer surface of the housing 22. This certainly leads to a permanent closure of the housing 22 which cannot be open anymore without destroying the components.

[0058] If the option to open shall continue to exist which is preferred for a threaded connection since otherwise the threaded connection would also be redundant. The sealing gap 9 can be circumferentially sealed tight in a radially upward direction by a sealing compound 8 not matter whether in closed condition of the screw connection 1 the face of the screw cap 21 still is arranged at a distance from the housing 22 or contacts the housing 22

[0059] It is appreciated that the sealing compound 8 has to resist the medium of the environment 100, e.g. salt water.

[0060] It is appreciated that by the same token that the tightness of an externally applied sealing compound 8 of this type is a function of the tightness of the adhesion of the sealing compound 8 of the components A, B which accordingly have to be brought into an optimum adhesion capable condition of their surfaces in this portion before applying the sealing compound in particular by degreasing, grinding or plasma beam treating or similar.

[0061] Between the one gasket, thus the left primary gasket 6 and the screw connection 1 additionally a supplemental second seal 16, e.g. the O-ring seal 13 illustrated herein can be arranged where the O-ring 13 is inserted into a seal groove machined into the circumferential surface which provides emergency sealing in case the adjacent primary seal 6 starts to leak.

[0062] FIGS. 2a, b, 3a, b illustrate the application of the principle according to the invention upon a sensor housing as illustrated in FIG. 2a, in an exploded view, wherein an only indicated electronic circuit 19 which according to FIG. 2a is arranged in the interior of the housing 22 with plural support elements and a sensor and wherein the housing shall be completely sealed relative to the ambient in spite of a cable 5 run out of the sensor housing 22 and wherein the screw connection 1 that is used for sealing the cable outlet is configured as described supra.

[0063] In this context the exploded view of FIG. 2a and the sectional view of FIG. 3a which axially extends through the cable pass through show that the housing 22 is made from a top shaped housing 22a and a cover 22b screw tight onto its open side as illustrated in particular in the top view of FIG. 2 in completely assembled condition, wherein the screwed on cover 22b is sealed relative to the pot shaped housing element 22a by two O-rings 13 that are arranged concentric with each other.

[0064] FIG. 3a, left half indicates that the housing can also be made from two half shells that are placed against each other with their open sides wherein the half shells are welded together by a weld 18 which can certainly only be done after the respective components are arranged in the housing, in particular the electronic circuit 19.

[0065] Since the sensor housing 22 however shall be open able again thereafter and thus not only at the cable pass through 15, but also for an access into the an interior of the housing 22 so that the electronics 19 arranged therein can be replaced or can be retrieved at least for test purposes primarily the variant illustrated in FIG. 3a on the right can be used, thus according to FIG. 2a together with a cable pass through 15 sealed by the threaded connection 1 according to the invention.

[0066] As illustrated in FIG. 2a the pot shaped housing component 22a has a circular outer circumference viewed from the open side wherein the circular outer circumference is flattened at one circumferential location and in the portion of this flat spot an pass through opening 24 is visible extending through the wall of the pot shaped housing element 22a into the interior through which the cable 5 can be run out by a threaded connection 1 as evident from the sectional view of FIG. 3a, b axially extending along the pass through opening 24.

[0067] On a one hand side it is visible that the housing spout 22′ protruding outward in FIG. 1a which is integrally configured at this location together with the housing 22 in the solution of FIGS. 2a, b, 3a, b is a separate threaded sleeve 22″ which is screwed into the pass through opening 24 of the housing 22 which certainly requires additional sealing between the housing 22 and the threaded sleeve 22″.

[0068] This screw connection 1′ also has to be sealed in outward direction which is done in this case with O-rings 13 arranged in the axial direction 10 of the pass through opening 24 and thus of the threaded sleeve 22 behind one another in an outer circumference of the threaded sleeve 22″ which are radially compressed when inserting and threading the threaded sleeve 22″ into the pass through opening 24 of the housing 22.

[0069] Thus, the threaded connection 1, according to the invention in analogy to the solution of FIG. 1a is thus provided between the outer circumference of the threaded sleeve 22″ as a component A and the component B threaded onto its outer circumference, the latter is thus provided as a threaded sleeve 20 with an axial pass through opening 15a for the cable 5 to be inserted instead of a face closed screw cap 21 as visible in FIG. 1a and a wrench contact surface 25 for applying an open end wrench at the threaded sleeve 20 as evident from FIG. 2a.

[0070] Sealing the cable pass through relative to the ambient 100 is provided in that the primary seal 6 configured as a seal element is not provided or not configured as a seal sleeve 7′ through whose axial pass through opening the cable 5 can be run when the seal sleeve 7 is not loaded.

[0071] However as soon as the seal sleeve 7 is axially compressed between the free face of the component A, thus the threaded sleeve 20′ and the component B of the threaded sleeve 20. The seal sleeve 7′ with its inner circumference based on the configuration of the seal element described in FIG. 1a presses on one side and of the components A, B on the other side in an entire circumference radially inward against the outer circumference of the cable 5 and seals relative thereto.

[0072] For the primary seal 6 at the other end, thus the left end in FIG. 3a, b of the annular chamber 3 there are the same options as described based on FIG. 1a, but not all the variants are drawn in FIG. 3a, b.

[0073] FIG. 3b in the upper half shows that in analogy to sealing the right face ring surface of the chamber 3 the O-ring 13 is pressed also in the axial direction between a shoulder of the component B and an opposite shoulder of the component A when tightening the threads 2a, b on the thread paths 2a, b.

[0074] This however requires a good sizing of another primary seal 6, in particular relative to the first primary seal 6 axially compressed due to the same threaded connection at a right end of the chamber 3. In the embodiment of FIG. 3b, top two axially offset primary seals 6 are used on one of the two sides of the thread 22a, b of the threaded connection 1, which thread is to be protected and this can also be performed on both sides in the axial direction of the engaging threads 22a, b of the threaded connection 1.

[0075] According to FIG. 3c it is an alternative to arranged the O-ring between an annular circumferential shoulder which forms an inner corner in the longitudinal sectional view of the first component and a annular circumferential edge of the second component which forms an outer edge in the longitudinal sectional view, which however is beveled, thus in the annular free space with triangular cross section between the two components.

[0076] This minimizes cross sectional variation of the O-ring 13 during compression and increases its service life.

[0077] FIG. 4 illustrates another solution how the risk of the threaded connection not being tight and thus the risk of destroying the threaded connection 1 can be minimized.

[0078] This solution is illustrated based on the threaded cap 20, thus a threaded sleeve with a closed face in analogy to FIG. 1a however can also be used in the same way for a threaded sleeve 21 and thus for a cable pass through or for any other threaded connection.

[0079] As evident from FIG. 4 two meshing threaded pairs 2a, b, 2′ a, b are arranged axially behind each other in the axial direction 10 wherein the threaded pairs respectively connect identical components A, B with one another in that two respective threads 2a, 2′a, 2b, 2′b are arranged behind one another at each of the components A, B.

[0080] Each thread pair 2a, b, 2′a, b is arranged in a separate tight chamber 3, 3′ in assembled condition which is also sealed relative to the other chamber so that in case one of the chambers 3, 3′ is not tight and thus the threads 2a, b or 2′a, b the other chamber 3′, 3 is still tight and the thread 2′a, b or 2a, b is not in contact with the ambient and can still perform its function.

[0081] As apparent the chambers 3, 3′ are also arranged axially offset from each other and between them there is [0082] at least one secondary seal 16 configured as a radially compressed O-ring seal as illustrated in the upper half of FIG. 4, [0083] Advantageously however also a primary seal 6 configured e.g. as an axially compressed O-ring seal as illustrated in the lower half of FIG. 4.

[0084] Thus, each of the chambers 3, 3′ on both sides of the respective screw connection 1 can include a secondary seal 16 or an additional primary seal 6 between the primary seal 6 and the screw connection 1.

[0085] Thus, the optimum safety will be provided in that the two chambers 3, 3′ between each other include at least two primary seals 6 and are sealed on their side that is axially oriented away from the other chamber 3′, 3 are sealed on their face side by respectively not only one but two primary seals 6.

REFERENCE NUMERALS AND DESIGNATIONS

[0086] 1 threaded connection

[0087] 2a, b thread

[0088] 3, 3′ chamber

[0089] 4a, b, c wall

[0090] 5 cable

[0091] 5′ cable section

[0092] 6 primary seal

[0093] 7 seal element

[0094] 7′ seal sleeve

[0095] 7″ seal ring

[0096] 7′″ seal plug

[0097] 8 sealing compound

[0098] 9 sealing gap

[0099] 10 axial direction

[0100] 11 first transversal direction

[0101] 12 second transversal direction

[0102] 13 O-ring sleeve

[0103] 14 support element

[0104] 15 cable pass through

[0105] 15a, b pass through opening

[0106] 16 secondary seal

[0107] 17 open wrench contact surface

[0108] 18 weld seam

[0109] 19 electronic circuit

[0110] 20 threaded sleeve

[0111] 21 screw cap

[0112] 22 housing

[0113] 22a, pot shaped housing element

[0114] 22b cover

[0115] 22′ housing spout

[0116] 22″ threaded sleeve

[0117] 23 flat surface

[0118] 24 pass through opening

[0119] 25 wrench contact surface

[0120] 100 ambient, sea water

[0121] A, B component