DE29513129U1 - High pressure connection system - Google Patents

Description

Kohler Schmid + Partner
Patent attorneys
Ruppmannstrasse 27

D-70565 Stuttgart

High pressure verb indunas sys t em

The invention relates to a connection system for extremely pressure-resistant pipe fittings with a standardized receiving body with a 24° connection, a union nut that is also standardized for producing a pressure-resistant connection, a pipe or a connecting pin for connecting other system components, a two-part ring in which the first ring is designed as a cutting or clamping ring which grips onto the outer wall of the pipe or connecting pin after the connection system has been installed, while the second ring is designed as a sealing ring that is sealed against the receiving body and against the pipe by means of an elastomer high-pressure seal, and which has an end face that is directly adjacent to an end face of the receiving body.

Such a connection system is known from DE 40 38 539 Cl.

To produce pressure-resistant connections, especially for fluids in high-pressure lines, mainly purely metallic sealing two-edge cutting rings are used in pipe fittings according to DIN 2353, which differ only slightly from one another in technical terms. The two-edge cutting rings fulfill both a sealing and a holding function for the corresponding connection system. However, increased user requirements have recently led to an increasing demand for additional elastomer seals. Simple sealing aids for cutting rings, such as those described in DE 41 03 266 Al or DE 80 17 944.8 Ul as well as in DE 42 29 502 Al, have not yet been able to establish themselves on the market because either the handling or the pipe preparation for the systems in question is too complex.

The latest state of the art was achieved by connecting systems with a two-part ring in conjunction with a DIN receiving body and a DIN union nut, as described, for example, in DE 40 38 539 Cl cited at the beginning. This known system advantageously separates the holding function on the one hand from the sealing function on the other. As is already known from older publications (see, for example, DE 27 12 614 Al) and as has been proven above all in practical applications, a two-part ring has considerable advantages over a one-part ring with a double function due to the double clamping and spring effect. In principle, the system according to DE 27 12 614 Al differs from the connecting system according to the above-cited

DE 40 38 539 Cl only because the former system did not use a DIN nozzle, which is why it was not able to establish itself on the market.

Even older is the pipe coupling system known from DT 15 25 666 C3, which is used in particular for gases, and which could not achieve a better sealing effect with an additional elastomer seal, since the purely metallic seal described there already guarantees the best leak tightness rates even in helium leak tests of the correspondingly coupled pipes.

The connection system according to DE 40 38 539 Cl has therefore in principle adopted the partial solutions already known from earlier publications (for the sealing element, e.g. DE 90 03 29 9.3 Ul; for the cutting ring and the cutting ring-side part of the sealing element, e.g. DE 27 12 614 Al or DT 15 25 666 C3) and implemented them in a DIN-compliant form. Nevertheless, the known system still has serious disadvantages:

All known cutting rings which are mounted on a block, i.e. where a front stop surface is flush with the front of the receiving body for a play-free fit, lose flexibility due to the rigid force connection, so that premature pipe breaks on the union nut side and even leaks can occur at the screw threads of the receiving body. The connection system known from DE 40 38 53 9 Cl is also mounted on a block in this way.

During assembly, there is generally the problem that the supposed end of assembly becomes visible when the over-

union nut is loosened again, but it is not possible to see when the cutting ring started cutting into the pipe and whether the effective cutting path is sufficient to ensure the full holding force. The known connection system does not offer any possibility of carrying out any further cutting that may be necessary, for example if the pipe was not quite at the pipe stop when cutting began, or if the pipe wall has deviated inwards.

In both cases, the pre-tensioning force on the thread would be reduced during rework and the union nut would come loose, so that the elastomer seal would no longer be chambered and would be pressed outwards through the resulting gap, which is why the sealing function would no longer be guaranteed when the seal is subsequently tightened. Accordingly, the only option left for a fitter is to tighten the union nut further, but this would most likely lead to excessive constriction of the pipe at the 90° cone of the union nut, so that premature pipe breakage due to notch effect would be the almost inevitable consequence.

Replacing the soft sealing element would also make no sense, because this would not fundamentally change the problem described above. If the sealing assembly were to loosen, a gap would again appear between the receiving body and the sealing ring, which is already present to a certain extent anyway due to the DIN tolerances between the sealing ring and the pipe. The only sealing element used in the known connection system, the elastomer high-pressure seal, would again be drawn into the gap and could then, according to the

other sides no longer or only incompletely fulfil its sealing function.

The object of the present invention is, in contrast, to create a connection system with the features of the type described at the outset, which combines the advantages of a system with a two-part ring with the improved sealing behavior of less rigid systems with as few technical changes as possible, whereby a subsequent exchangeability of damaged sealing elements should be made possible.

According to the invention, this object is achieved in that the elastomer high-pressure seal comprises a first elastomer sealing element arranged between the end face of the receiving body and the sealing ring and a second sealing element arranged between a surface of the sealing ring facing the pipe or connection pin and the outer wall of the pipe or connection pin.

Instead of using a single elastomeric sealing element, which is chambered between the conical surface of the holding body, the outer wall of the pipe and the radial ring surface also located in the conical area, according to the invention, two spatially separated sealing zones are created, namely by the first elastomeric sealing element between the sealing ring and the receiving body and by the second elastomeric sealing element between the sealing ring and the pipe. On the one hand, this retains the advantages of a specialized sealing ring, which no longer has to take on a holding function, but only ensures the sealing function by means of an elastomeric sealing element, on the other hand, the sealing behavior is achieved by the spatial separation of the two sealing points, the advantages of which can be seen on

already known from DE 42 29 502 Al, have been considerably improved.

There is also the further advantage that the elastomer seal, viewed in the direction of the fluid to be sealed to the outside, is located in front of the metal cutting seal through the cutting ring, so that the cutting seal acts as a kind of second safety device in the event of failure of the elastomer seal between the sealing ring and pipe, whereby compared to the known connection system according to DE 42 29 502 Al, the arrangement of the second elastomer seal immediately after the cutting ring means that the material build-up on the outside of the pipe caused by the cutting ring significantly improves the sealing properties of the second elastomer seal.

If the elastomer high-pressure seal subsequently becomes damaged, the connection system according to the invention can be released by unscrewing the union nut, whereby the cutting ring remains essentially fixed in place in the pipe. The sealing ring with the elastomer sealing elements can then be easily replaced with a replacement sealing ring. Alternatively, the elastomer sealing elements can also be replaced on their own without having to fear the negative effect of elastomer material being drawn into a gap described above. Another simple subsequent repair option for an elastomer seal that has become leaky in the connection system according to the invention is to insert a conventional O-ring into the cone area of the receiving body, which creates at least one sealing connection, as is known per se from DE 40 38 53 9 Cl cited at the beginning.

Advantageously, the sealing ring with the elastomer sealing elements according to the connection system according to the invention can also be used to replace a defective conventional sealing ring in an already installed known system according to the state of the art if a leak should occur there. Due to the boundary conditions when using a standardized receiving body and a DIN union nut in the connection system according to the invention, there is geometric compatibility of the two-part ring, so that it only has to be ensured that the sealing ring of the connection system according to the invention fits with the latter on its side facing the cutting or clamping ring.

In an advantageous embodiment of the connection system according to the invention, at least the first elastomeric sealing element, and preferably also the second elastomeric sealing element, is accommodated in a recess in the sealing ring. This guarantees essentially complete chambering of the elastomeric sealing material.

The first and/or second elastomeric sealing element can be present in embodiments as a separate part in the form of an O-ring, a flat sealing element or the like. Alternatively, the elastomeric sealing element can also be firmly connected to the sealing ring, in particular vulcanized or glued on. The advantage of the first embodiment is that a damaged sealing element can be replaced separately without the entire sealing ring having to be replaced. The advantage of the second alternative is that the elastomeric sealing elements firmly connected to the sealing ring are easier to handle because only a single component is used and

must be positioned.

In a particularly advantageous embodiment of the connection system according to the invention, the front surface of the sealing ring limits the section of the sealing ring that projects furthest axially in the direction of the receiving body, so that no parts of the sealing ring protrude into the conical 24° recess of the receiving body. Such embodiments can be used in particular in conjunction with special sockets without a cone, which replace the conventional standardized receiving body according to DIN and can, for example, have a reduced pipe insertion depth. Such special sockets can have significantly greater mechanical stability than the standardized receiving body and are therefore particularly suitable for use in the event of extreme load changes in the high-pressure fluid system to be connected or at pressures far above the limit values prescribed by DIN. This opens up completely new areas of application for the connection system according to the invention.

The above-mentioned embodiment has advantages even when using a DIN mounting body: it is particularly easy to manufacture due to the continuous front surface and can therefore be offered at low cost. In addition, significantly less sealing material is required, since no large chamber has to be filled as in the prior art, but the sealing material only has to be present between the opposite sealing surfaces of the mounting body and the sealing ring.

In a particularly preferred development of this embodiment, the first and second elastomeric sealing

element are connected in one piece and are therefore much easier and cheaper to manufacture than two separate sealing elements. In particular, only a single work step is required when vulcanizing the elastomer material onto the sealing ring.

The above-mentioned embodiment can be further developed in such a way that the elastomer sealing material of the elastomer high-pressure seal is arranged in an approximately L-shape around the radial inner edge of the sealing ring facing the pipe or connection pin.

Alternatively, in other embodiments, it can be provided that the sealing ring has an approximately conical recess on the radial inside of its end face facing the receiving body, opening towards the receiving body, and that a sealing element with an approximately triangular cross-section is provided adjacent to the conical recess, one outer surface of which rests on the pipe or connecting pin, and the other outer surface of which rests at least partially on the end face of the receiving body. This embodiment has the advantage over the above-mentioned one of being easier to manufacture the conical recess on the sealing ring, while the alternative embodiment ensures a better hold of the sealing element on the sealing ring due to its geometric design.

It is advantageous for both embodiments if the outer edge of the L-shaped or triangular sealing element, which is arranged radially inward and faces the receiving body, is bevelled or rounded. This saves unnecessary sealing material, which does not contribute to the seal anyway.

As an alternative to the above-mentioned embodiments, however, the connection system according to the invention can also have a circumferential shoulder on the inside of the sealing ring, which protrudes into the conical opening of the receiving body when the connection system is assembled. This ensures particularly good chambering of the first sealing element, because the 24° cone of the receiving body also partially acts as a chamber wall. In addition, this creates an enlarged sealing surface between the sealing element and the receiving body.

In an advantageous development of this embodiment, it is provided that the first and second elastomeric sealing elements are formed from a layer of elastomeric material that is pulled over the circumferential shoulder of the sealing ring, is integrally connected and is preferably vulcanized onto the sealing ring. Such a connected layer is particularly simple and inexpensive to produce.

In order to save material and weight, in a further development the layer of elastomer material can have a small thickness of preferably approximately 1/2 mm or less, which is usually completely sufficient.

A particularly preferred embodiment of the connection system according to the invention is one in which the circumferential shoulder is essentially cylindrical and has an axial length such that it does not come into contact with the 24° cone of the receiving body when the connection system is assembled. This makes the connection system according to the invention even more mechanically flexible because there is no need for another rigidly guided force-locking connection. The screw-in thread of the

This relieves the load on the receiving body and the requirements for the dimensional accuracy of the pipe, for example in a bent fluid line system, are lower without any loss of safety.

In an alternative embodiment, the circumferential shoulder is designed to taper towards the receiving body, preferably at an angle of approximately 24°. The conical part of the sealing element then takes on a mechanical guiding function. In addition, considerably less sealing material is required on the first elastomeric sealing element.

Particularly preferred is an embodiment of the connection system according to the invention in which external thread segments made of elastomer material that match the internal thread of the union nut are vulcanized or glued to the outer circumference of the sealing ring, preferably distributed symmetrically around the circumference. In this case, parts that are pre-assembled in the delivery state can be held in the union nut and can be easily separated from one another by simply turning them without the use of tools.

In a further particularly preferred embodiment of the connection system according to the invention, it is provided that the cutting or clamping ring has a protruding, circumferential shoulder which, when the connection system is assembled, projects into a conical recess of the sealing ring facing the cutting or clamping ring and arranged radially inward, and which, starting from an approximately cylindrical extension piece, has a conical slope sloping towards the sealing ring, the slope angle of which is greater than the slope angle of the corresponding conical recess.

removal of the sealing ring. In the overtightening area, this design results in a constriction and clamping in the middle area of the cutting ring relative to the sealing ring and the pipe. This prevents or at least reduces a damaging notch effect of the cutting ring on the pipe due to the free end of the cutting ring being tilted relative to the pipe, so that a higher pressure safety level can be achieved with the connection system.

Further advantages of the invention emerge from the description and the drawing. Likewise, the features mentioned above and those listed below can be used individually or in combination in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for the description of the invention.

Show it:

Fig. 1 shows a half longitudinal section through a connection system according to the invention for extremely pressure-resistant pipe fittings;

Fig. 2a in the left half a side view of a two-part ring of an embodiment of the connection system according to the invention and in the right half a schematic longitudinal section of the same;

Fig. 2b is a frontal plan view of the two-part ring according to Fig. 2a;

■ ·

Fig. 3 shows a schematic half longitudinal section through a two-part ring and a receiving body of an embodiment of the connection system according to the invention with a sealing ring without a shoulder;

Fig. 4a is a longitudinal section as in Fig. 3, but with a one-piece elastomeric sealing element in L-shape;

Fig. 4b a longitudinal section as in Fig. 4a, but with cutting ring, sealing ring and receiving body in the prescribed final position, fully assembled without overtightening;

Fig. 5 is a longitudinal section as in Fig. 3, but with a triangular, one-piece sealing element; and

Fig. 6 is a longitudinal section as in Fig. 3, wherein the sealing ring has a circumferential shoulder protruding into the 24° cone of the receiving body.

In the embodiment of a connection system according to the invention for extremely pressure-resistant pipe fittings shown in Fig. 1, the upper half of the screw connection assembly in relation to an axis of symmetry a can be seen in a half longitudinal section in the tightened state. A pipe 7, which could also be designed as a connecting pin, for example, is connected in a high-pressure sealing manner to a standardized receiving body 1, which has a 24° inner cone 19, by means of a standardized union nut 2, a cutting ring 3, which can be designed as a one- or two-edge cutting ring or as a clamping or wedge ring for holding the pipe, and a sealing ring 4. In the embodiment shown, the thread tightening of the union nut 2 against the receiving body 1

the cutting ring 3 has been deformed in such a way that it has cut into the outer surface of the tube 7 and thus ensures that the assembly is firmly seated. The sealing ring 4 has a first elastomeric sealing element 5, which abuts against an end face 8 of the receiving body 1, and a second elastomeric sealing element 6, which is pressed against the outer surface of the tube 7, which abuts against a tube stop surface 18 of the receiving body 1 on the end face.

Instead of a standardized receiving body 1 with a 24° cone, a special socket (not shown in the drawing) for extremely high pressures with a smaller pipe insertion depth and without a receiving cone could also be used in the connection system according to the invention. The first elastic sealing element 5 would then still take over the sealing function against the corresponding end face of the socket.

In addition, additional soft seals can be used in the event of repairs, for example O-rings or flat sealing rings made of elastomer material, which then take over the sealing function of a possibly damaged first or second sealing element. Such additional soft seals could then again be chambered in the 24° cone of the receiving body, as is the case with the state of the art.

In Fig. 2a, a side view of the cutting ring 3 shown in Fig. 1 and the sealing ring 4 is shown on the left side. The right side of Fig. 2a shows a schematic longitudinal section through the two-part ring 3, 4, while Fig. 2b shows a top view of the sealing ring 4 according to Fig. 2a. On the outer circumference of the sealing ring 4, external thread segments 20 made of

elastomeric material, which can be vulcanized or glued to the sealing ring 4. This makes it possible to create a bayonet-type screw connection between the sealing ring 4 and the union nut 2, which acts as a pre-assembly holder for the union nut 2, cutting ring 3 and sealing ring 4 and can be easily removed for the purpose of final assembly.

Fig. 3 shows an enlarged sectional view of elements of the connection system according to Fig. 1, namely the receiving body 1, the sealing ring 4 and the cutting ring 3 in the non-tightened, pre-assembled state. The sealing ring 4 abuts with its end face 9 against the end face 8 of the receiving body 1, whereby the first elastomeric sealing element 5, which is chambered in a recess 25 in the end face 8 of the sealing ring 4, is pressed against the end face 9 of the receiving body 1, which acts as a sealing surface. The second elastomeric sealing element 6 lies sealingly against the outer surface of the pipe, not shown in Fig. 3.

Fig. 4a shows an embodiment of the sealing element 4', in which the two elastomeric sealing elements are connected to one another and form a one-piece sealing element 21, which in the embodiment shown is arranged approximately L-shaped around the radial inner edge 22 of the sealing ring 4'.

In Fig. 4b, the sealing assembly is shown in the tightened state. The union nut (not shown in the figure) presses on the conical surface 10 of the cutting ring 3, causing the cutting ring 3 to slide with its front section 11 under the inner conical surface 12 of the sealing ring 4'. This causes the front section 11 to be pushed inwards towards the pipe 7.

deflected and its lower edge grips the outer surface of the pipe 7. At the same time, the front section 11 forms a chamber wall for the pressure-resistant chambering of the elastomer sealing element 21. As in the prior art, the end surface 14 of the cutting ring 3 no longer serves as a stop for the cutting ring-side front surface 13 of the sealing ring 4', which would only come into contact with the front surface 13 in the event of extreme overtightening, but rather the conical surface 15 on the cutting ring 3, against which the inner edge 18 of the rear front surface 13 runs.

Due to the "possible assembly errors described at the beginning of such a high-pressure connection system, it is advantageous if the cutting ring 3 can be tightened. In doing so, a further axial cutting path is covered in the system according to the invention. At the same time, not only is there a further increase in the pipe clamping force in the area of the conical surface 10 of the cutting ring 3, but also a compression and reduction of the axial length of the cutting ring 3 in its middle area 16, which leads to a tight grip on the pipe 7. Such a geometry of the cutting ring 3 ensures that when the overtightening area is reached during the assembly process, the fitter feels a clearly recognizable force signal as a result of a disproportionately large increase in force as soon as the inner edge 18 of the sealing ring 4' hits the conical surface 15 of the cutting ring 3. Even if overtightening is possibly necessary, with the existing geometry of the cutting ring 3, no harmful notch effect occurs due to Pipe constriction, but rather a uniform distribution of force is achieved over the area spanned between the central region 16 and the ring outlet 17 of the cutting ring 3, which is also used for pipe support.

A further embodiment of the connection system according to the invention is shown in Fig. 5, where the sealing ring carries a one-piece, substantially triangular-shaped elastomeric sealing element 23 which has a bevel 24 on its radially inner outer edge.

Finally, Fig. 6 shows a further embodiment, in which a sealing ring 4''' has a circumferential shoulder 27 radially on the inside, which protrudes into the conical opening 19 of the receiving body 1 when the connection system is assembled. The axial length of the shoulder 27 is selected such that it does not hit the conical surface 19 of the receiving body 1 even when the connection system is tightened. The circumferential shoulder 27 creates an almost completely closed chamber 26 for the first elastomeric sealing element 5'.'

Alternatively, in an embodiment not shown in the drawing, the circumferential shoulder can be designed to be essentially conical, preferably tapering towards the receiving body 1 at an angle of approximately 24°. As a result, when the connection system is tightened, the conical surface 19 of the receiving body 1 comes into contact, with the conical shoulder of the sealing ring sliding over the conical surface 19 as a guide surface.

Overall, the sealing system according to the invention offers a better pipe support for absorbing vibrations and alternating bending loads and, in particular, allows the compensation of greater inaccuracies in the pipe axis than before thanks to the front-side elastomer seal on the support body, whereas the state of the art requires precise guidance

of the sealing ring between the pipe outer diameter and the 24° conical surface of the receiving body was an absolute prerequisite for the tightness of the known system. With the connection system according to the invention, even a limited overtightening is possible even with thin-walled pipes, with which a further cutting is effected in order to compensate for tolerances between the pipe outer diameter and the inner diameter of the two-part ring.

Claims (16)

Protection claims 1. Connection system for extremely pressure-resistant pipe fittings with a standardized receiving body (1) with a 24° connection, a union nut (2) that is also standardized for creating a pressure-resistant connection, a pipe (7) or a connecting pin for connecting other system components, a two-part ring in which the first ring is designed as a cutting or clamping ring (3) which, after assembly of the connection system, grips onto the outer wall of the pipe (7) or connecting pin, while the second ring is designed as a sealing ring (4) which is sealed against the receiving body (1) and against the pipe (7) by means of an elastomer high-pressure seal and which has an end face (9) which is directly adjacent to an end face (8) of the receiving body (1), characterized in that the elastomer high-pressure seal comprises a first elastomer sealing element (5; 5') arranged between the end face (8) of the receiving body (1) and the sealing ring (4; 4 ¹ ; 4''; 4 ¹ '') and a second sealing element (6) arranged between a surface of the sealing ring facing the pipe (7) or connection pin and the outer wall of the pipe or connection pin. 2. Connection system according to claim 1, characterized in that at least the first elastomeric sealing element (5; 5'), preferably also the second elastomeric sealing element (6) is accommodated in a recess (25; 26) of the sealing ring (4; 4'''). 3. Connection system according to claim 1 or 2, characterized in that the first and/or the second elastomeric sealing element (5, 6; 5 ¹ ) is present as a separate part in the form of an O-ring, a flat sealing element or the like. 4. Connection system according to one of the preceding claims, characterized in that the first and/or the second elastomeric sealing element (5, 6; 5 ^! ) is firmly connected to the sealing ring, in particular vulcanized or glued thereto. 5. Connection system according to one of the preceding claims, characterized in that the end face (9) of the sealing ring (4; 4'; 4 ¹¹ ) delimits the section of the sealing ring (4; 4';4' ¹ ) which projects furthest axially in the direction of the receiving body (1) on the end face. 6. Connection system according to claim 5, characterized in that the first and the second elastomeric sealing element are integrally connected to one another. 7. Connection system according to claim 6, characterized in that the elastomeric sealing material (21) of the elastomeric high-pressure seal is arranged approximately L-shaped around the radial inner edge (22) of the sealing ring (4') facing the pipe (7) or connection pin. 8. Connection system according to claim 6, characterized in that the sealing ring (4 ^1! ) has on its end face facing the receiving body (1) a roughly conical recess radially inwardly, opening towards the receiving body (1), and that a sealing element (23) of roughly triangular cross-section is provided adjacent to the conical recess, one outer surface of which rests on the pipe (1) or connecting pin, and the other outer surface of which rests at least partially on the end face (8) of the receiving body (1). 9. Connection system according to claim 7 or 8, characterized in that the radially inwardly arranged outer edge of the L-shaped or triangular sealing element (21 or 23) facing the receiving body (1) is bevelled or rounded. 10. Connection system according to one of claims 1 to 4, characterized in that a circumferential shoulder (27) is provided radially on the inside of the sealing ring (4'''), which in the assembled state of the connection system projects into the conical opening of the receiving body (1). 11. Connection system according to claim 10, characterized in that the first and second elastomeric sealing elements are formed from a layer of elastomeric material which is pulled over the circumferential shoulder of the sealing ring and is integrally connected and preferably vulcanized onto the sealing ring. 12. Connection system according to claim 11, characterized in that the layer of elastomer material has a small thickness of preferably approximately 1/2 mm or less. 13. Connection system according to one of claims 10 to 12, characterized in that the circumferential shoulder (27) is essentially cylindrical and has an axial length such that it does not abut the 24° cone of the receiving body (1) in the assembled state of the connection system. 14. Connection system according to one of claims 10 to 12, characterized in that the circumferential shoulder is designed to taper conically towards the receiving body (1), preferably at an angle of approximately 24°. 15. Connection system according to one of the preceding claims, characterized in that external thread segments (20) made of elastomer material, which are vulcanized or glued to the outer circumference of the sealing ring (4; 4'; 4 ¹¹ ; 4' ¹¹ ) and match the internal thread of the union nut (2), are arranged, preferably distributed symmetrically around the circumference. * ·♦ • · 16. Connection system according to one of the preceding claims, characterized in that the cutting or clamping ring (3) has a protruding, circumferential shoulder (11) which, in the assembled state of the connection system, is inserted into a cutting or clamping ring (3) facing, radially inwardly arranged conical recess (12) of the sealing ring (4 ¹ ) and which, starting from an approximately cylindrical extension piece, has a conical slope sloping towards the sealing ring (15) whose pitch angle is greater than the pitch angle of the corresponding conical recess (12) of the sealing ring. ~-