AU2013307584A1

AU2013307584A1 - Fitting, system comprising such a fitting, and sealed connection with such a fitting

Info

Publication number: AU2013307584A1
Application number: AU2013307584A
Authority: AU
Inventors: Andreas Huette; Bernd Koschig; Kai-Michael Meissner; Sudi Sinoplu
Original assignee: Viega GmbH and Co KG
Current assignee: Viega Technology GmbH and Co KG
Priority date: 2012-09-03
Filing date: 2013-08-05
Publication date: 2015-03-12
Anticipated expiration: 2033-08-05
Also published as: EP2893241B1; WO2014032911A1; AU2013307584B2; EP2703707B1; DK2703707T3; ES2604013T3; BR112015004610B1; HRP20161554T1; RU2589974C1; EP2703707A1; SI2893241T1; HUE032239T2; EP2893241A1; LT2893241T; MX356018B; BR112015004610A2; DE102012108146B4; DE102012108146A1; MX2015002733A; PL2893241T3

Abstract

Disclosed is a fitting to be sealingly connected to a tubular end (18), in particular of a tube, comprising an outer tubular fitting body (6) and an inner tubular fitting body (12), the outer fitting body (6) having an outer support section (8) which is made at least partially of plastic and which is to be inserted into the tubular end (18), the inner fitting body (12) having an inner support section (14) which is made at least partially of metal and which is to be inserted into the tubular end (18), the inner support section (14) being arranged at least partially within the outer support section (8), the inner peripheral surface (20) of the outer support section (8) and the outer peripheral surface (22) of the inner support section (14) being sealed off from each other in at least some regions (24a, 24b, 24c), and at least one cavity (28a, 28b) being formed between the inner peripheral surface (20) of the outer support section (8) and the outer peripheral surface (22) of the inner support section (14).

Description

Fitting, System Comprising such a Fitting and Sealed Connection with such a Fitting The invention relates to a fitting for sealed connection to a tubular end, in particular of a 5 tube. Furthermore, the invention also relates to a system having such a fitting and having an outer sleeve. Lastly, the invention relates to a sealed connection having such a fitting and a tubular end. In the prior art, it is known to connect tubular ends with the aid of fittings. In this case, 10 the tubular ends may be either those of a tube or those of other components, for example mountings. By means of the fittings, for example, it is possible either to connect tubes to one another or to connect tubes to other components, for example faucets, valve pieces or the like. Furthermore, the fitting may, for example, also already be configured as a T-piece. [5 In order to produce sealed connections also in the field of gas pipes or liquid pipes, for example water pipes and in particular drinking water pipes, fittings are preferably used. In this case, however, strict requirements for the connection must be satisfied in order to ensure a permanently sealed connection. If the medium carried in the pipes is a gas, 20 the connection must withstand a pressure of up to 10 bar under temperature variations of from -20 to +60'C over several days. If the medium carried is water, the connection must withstand temperature variations of from room temperature or cold water up to 95'C, and must also be as corrosion-resistant as possible. 25 Whereas metal was for a long time used as material for the tubes and the components to be connected, these are now also regularly made at least partially of plastic. In particular, tubes comprising plastic are often used in the form of composite tubes or multilayer composite tubes. This, however, gives rise to problems in connection of the tubular ends, likewise comprising plastic, to fittings still made of metal. 30 -2 The plastic used for the tubular ends usually has a higher elasticity than the fitting made of metal. Thus, for example, if deformation takes place the plastic can return again to its original state, whereas the metal cannot make the deformation or may be irreversibly deformed thereby. For this reason, with a metal fitting, owing to the elasticity of the 5 tubular end comprising plastic, it is not readily possible to produce a permanently sealed connection between the fitting and the tubular end. This problem has been solved in the prior art by using so-called sealing elements, for example 0-rings. To this end, a sealing element is positioned between the outer 10 circumferential surface of the fitting and the inner circumferential surface of the tubular end (internally sealing) or between the inner circumferential surface of the fitting and the outer circumferential surface of the tubular end (externally sealing). The elasticity of the sealing element can compensate for the lack of elasticity of the metal fitting. 15 Problematic in this respect is, however, on the one hand that extra care is necessary during installation or mounting owing to the sealing element additionally to be provided, so that the sealing element does not for example slip. Inadvertent leaks can occur when using such sealing elements. 20 On the other hand, for use of the fitting for components carrying gas on the one hand, and for components carrying water on the other hand, owing to the different effects of the medium on the elastic sealing elements it is respectively necessary to provide different sealing elements or even different fittings. This leads to further disadvantages such as more elaborate production or great care required during mounting because of 25 the need for different sealing elements or fittings, depending on the medium carried. It is likewise known from the prior art, in the case of internally sealing fittings, first to widen the tubular end comprising plastic and then to connect the fitting to the fitting by sliding it on. By a restoring force of the tubular end acting radially inwards, sufficient 30 sealing to the fitting can be achieved in this way. A disadvantage with this is, however, that on the one hand an additional installation step is required with the widening of the -3 tubular end, and on the other hand the material of the tubular end is greatly stressed by the widening process, which can lead to separation of layers particularly in the case of composite or multilayer composite tubes. 5 It is likewise conceivable to dispense with a fitting made of metal and instead to use a fitting made entirely of plastic. However, the acceptance of such fittings on the market is not sufficient in order to be able to replace metal fittings. Furthermore, metal fittings can impart increased stability to the connection. 10 On the basis of this, the technical object of the present invention is to provide a fitting which allows sufficient sealing to a tubular end, while at the same time avoiding the aforementioned problems. In addition, a system and a sealed connection having such a fitting are furthermore to be provided. 15 According to a first teaching of the present invention, the object is achieved by a fitting for sealed connection to a tubular end, in particular of a tube, having an outer tubular fitting body and having an inner tubular fitting body, wherein the outer fitting body comprises an outer support section, consisting at least partially of plastic, for insertion into the tubular end, wherein the inner fitting body comprises an inner support section, 20 consisting at least partially of metal for insertion into the tubular end, wherein the inner support section is at least partially arranged inside the outer support section, wherein the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section are sealed against one another in sections, and wherein at least one cavity is formed between the inner circumferential 25 surface of the outer support section and the outer circumferential section surface of the inner support section. A support section is in this case intended to mean the section of the respective fitting body which can be inserted into the tubular end, and which can therefore support the 30 tubular end from the inside. To this extent, the support section represents an internal support section or internal support body. The fitting body may, however, in particular -4 comprise further sections which adjoin the support sections, for example transition or base sections, or even further support sections which are used for connection to further components. 5 The effect achieved according to the invention is that a support section consisting at least partially of plastic overlaps at least locally, as seen in the radial direction, with a support section consisting at least partially of metal, since the internal support section is arranged at least partially inside the outer support section. These support sections can then be inserted into the tubular end. Preferably, the internal support section is in this 10 case arranged essentially coaxially inside the outer support section. The fact that the inner circumferential surface of the outer support section and the outer circumferential surface of the internal support section are sealed against one another in sections prevents the medium being carried, i.e. in particular both gas and water, from 15 being able to emerge between the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section. The sealing of the fitting against the tubular end can then take place between the inner circumferential surface of the tubular end and the outer circumferential surface of the 20 outer support section. The effect achieved by at least one cavity being formed between the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section is that, despite the use of a fitting body made of 25 metal, a sealed connection to a tubular end can be achieved, even if the tubular end consists at least partially of a material that has an elasticity or resilience, which has not previously been readily possible to seal with a metal fitting. Since the at least one cavity provides space radially inwards for the outer support section to yield, the elasticity of the outer support section, consisting at least partially of plastic, is modified in such a 30 way that it can compensate for possible resiliences of the tubular end, so that the sealing between the inner circumferential surface of the tubular end and the outer -5 circumferential surface of the outer support section is preserved. The elasticity of the outer support section may in this case, in particular, be achieved by bending forces on the one hand and by the hoop stress of the plastic of the outer support section on the other hand. 5 In other words, the outer support section is thus given the opportunity to bend radially inwards and provide a restoring force radially outwards which is sufficient for the sealing. In this way, a fitting having a fitting body consisting at least partially of a metal can be used, but at the same time the sealing behaviour of a fitting made entirely of 10 plastic can be replicated. As a result, it is thus possible to provide a fitting accepted by the market, which consists at least partially of metal and is suitable both for gas conduits and for water conduits, since in particular it is not necessary to provide a sealing element and it is furthermore 15 not necessary to carry out widening of the tubular end, so that simple installation is possible. Such a fitting is therefore suitable, in particular, for sealed connection to a tube comprising plastic or a composite or multilayer composite tube, preferably to a 20 composite or multilayer composite tube comprising plastic. According to one configuration of the fitting according to the invention, at least one radially outward elevation is provided on the outer circumferential surface of the outer support section, particularly in the form of a profiling, which is arranged at least 25 partially in the region of the at least one cavity. It has been found that, by the at least one radially outward elevation, for example in the form of a radially outwardly directed local thickening of the outer support section, particularly effective sealing can be achieved in sections between the inner 30 circumferential surface of the tubular end and the outer circumferential surface of the outer support section. The at least one radially outward elevation may, in particular, be -6 configured circumferentially on the outer circumferential surface of the outer support section and/or in the form of a serration, which is preferably configured in the shape of a barb. In this way, it is additionally possible to reduce the risk of that the tubular end will inadvertently slip off or slip down from the outer support section. 5 In order to obtain particularly effective sealing, the at least one radially outward elevation is preferably provided only in the sections on the outer circumferential surface of the outer support section in which the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support are not sealed 10 against one another in sections. The at least one radially outward elevation on the outer circumferential surface of the outer support section is thus, in particular, to be provided in the regions of the cavities. In this way, particularly advantageous elasticity properties for sealing against the inner circumferential surface of the tubular end are imparted to the fitting. This is because the bending forces and the hoop stresses of the plastic of the 15 outer support section can thus be used particularly effectively for sealing against the inner circumferential surface of the tubular end by means of the at least one radially outward elevation provided. In principle, it is possible that the cavity can be filled with different fillers or media, for 20 example gases or fibres. It has, however, been found particularly advantageous for at least one cavity between the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section to be an air-filled, preferably annularly circumferential cavity. In other words, an air chamber is thus produced, into which the outer support section can bend. It has been found that an air 25 filled cavity imparts advantageous properties in relation to elasticity and restoring forces to the outer support section of the outer fitting body of the fitting, so that effective sealing can be achieved, in particular of tubular ends of tubes comprising plastic. The at least one cavity is preferably a cavity sealed from the medium and/or from the 30 environment. This can be achieved by corresponding arrangement of the sections in -7 which the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section are sealed against one another. If, according to another configuration, at least one cavity between the inner 5 circumferential surface of the outer support section and the outer circumferential surface of the inner support section is formed by at least one recess on the outer circumferential surface of the inner support section and/or the inner circumferential surface of the outer support section, the formation of the at least one cavity can be carried out particularly simply. The recesses may, for example, be provided by 10 reductions in cross-section of the inner support section of the inner fitting body. In principle, the local sealing of the inner circumferential surface of the outer support section against the outer circumferential surface of the inner support section may be carried out differently, for example by means of adhesive bonding, screwing or latching. 15 Particularly advantageously, however, according to another configuration of the fitting according to the invention, the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section are sealed against one another in sections by means of a force-fit connection, in particular a press fit. Owing to the force-fit connection, it is readily possible to provide a reliably sealed connection 20 between the inner circumferential surface of the outer support section and the outer circumferential surface of the inner support section. If a press fit is provided in sections, in these sections the outer circumferential surface of the inner support section has an oversize in comparison with the inner circumferential surface of the outer support section. Such a press fit can be produced by widening the outer fitting body at least in 25 the regions of the outer support section and sliding it onto the inner fitting body. An effective press fit or oversize fit can then be produced by the radial contraction of the outer fitting body in the widened region, caused by the memory effect. Particularly preferably, the fitting according to the invention is configured without a 30 sealing ring, in particular without a sealing element. It has been found that a permanently sealed connection can be produced even without additional sealing rings -8 or sealing elements. In this way, in particular, it is also not necessary to provide different sealing elements and fittings, depending on the medium carried. According to a next configuration of the fitting according to the invention, the end of the 5 outer support section facing towards the tubular end extends beyond the end of the inner support section facing towards the tubular end in the axial direction. In this case, the ends of the support sections facing towards the tubular end are understood as the ends of the support sections which are inserted into the tubular end. In this way, in particular, a region freely bending inwards can be provided on the end of the outer 10 support section facing towards the tubular end. In this region, in particular, an increased wall thickness of the outer support section may be provided, so that in this region the outer support section practically corresponds to a support section of a fitting made entirely of plastic. Advantageous sealing properties of a support section made entirely of plastic can in this way be combined with the fitting according to the invention. Likewise, 15 in this way, an inner support section, or support section, which is shorter as seen in the axial direction may in this way be provided, or this support section does not need to be inserted so far into the outer support section. If the end of the inner fitting body facing away from the tubular end extends beyond the 20 end of the outer fitting body facing away from the tubular end in the axial direction, further components, such as fittings, tubes or valves, can be connected to the inner fitting body. Since the inner fitting body may in particular be made entirely of metal, in this case further components may be connected by means of methods known from the prior art, for example by crimping. It is likewise conceivable to provide the end of the 25 inner fitting body facing away from the tubular end likewise with an inner support section, and to use it for a fitting according to the invention. Preferably, the inner fitting body, in particular the inner support section, consists at least partially of copper, brass, aluminium and/or steel, in particular ferritic or 30 austenitic stainless steel. An alloy or combination thereof may also be provided. It is particularly preferred, however, for the inner fitting body to be made of copper or a -9 copper alloy. In this way, advantageous migration behaviour, good corrosion resistance, good strength and good processability, in particular good machinability, as well as advantageous casting properties, can be combined. 5 Preferably, the outer fitting body, in particular the outer support section, consists at least partially of polyphenyl sulfone (PPSU), polyvinylidene fluoride (PVDF), non crosslinked polyethylene (PE-RT), crosslinked polyethylene (PE-Xa, PE-Xb, PE-Xc), polybutene and/or polypropylene. It is particularly preferred, however, for the fitting body to be made of polyphenyl sulfone (PPSU). The use of such a plastic material has the 10 advantage that the fitting is also suitable for pipelines in which drinking water is carried. The object mentioned in the introduction is furthermore achieved, according to a further teaching of the invention, by a system having a fitting according to the invention and having an outer sleeve, wherein an annularly circumferential recess for the tubular end 15 to be connected is formed between the inner circumferential surface of the outer sleeve and the outer circumferential surface of the outer support section. By providing an outer sleeve in the system according to the invention, a radially inward force can be exerted on the tubular end in the region of the inner or outer support 20 section. In this way, it is readily possible to achieve a particularly durably sealed connection with the system according to the invention. The outer sleeve may, for example, be essentially cylindrical and arranged essentially coaxially with the inner or outer fitting body. 25 The outer sleeve may, for example, be formed in multiple parts, for example two parts. For example, the outer sleeve and may comprise a union nut and a clamping body. Here, the outer sleeve may also have one or more radially inward projections on its 30 inner circumferential surface, in order to achieve fixing relative to the tubular end to be - 10 inserted. The sleeve may also comprise one or more recesses, in order to be able to check correct positioning, in particular of the inserted tubular end. Furthermore, the inner or outer fitting body may comprise a stop, for example in the 5 form of a flange, for axial positioning of the outer sleeve. Such a stop may also be formed as a separate part which is connected, for example latched, to the inner or outer fitting body. One configuration of the system according to the invention is characterised in that the 10 outer sleeve is connected directly or indirectly to the inner and/or the outer fitting body, in particular to a base section adjoining the outer support section of the outer fitting body. The outer sleeve may be connected directly to the inner or outer fitting body by the 15 outer sleeve being connected to the outer circumferential surface of the inner or outer fitting body with a force fit, form fit or material fit, for example latched, adhesively bonded on or screwed. Corresponding connection means may, in particular, be provided on the outer circumferential surface of the base section or flange section of the outer fitting body. 20 According to a further teaching of the connection according to the invention, the object is also achieved by a sealed connection, having a fitting according to the invention and having a tubular end, wherein the tubular end is positioned on the outer support section of the outer fitting body. 25 In this way, the inner circumferential surface of the outer tube may be sealed at least locally by the outer circumferential surface of the outer support section of the fitting according to the invention, in particular by at least one radially outward elevation on the outer circumferential surface of the outer support section. 30 - 11 In particular, the tubular end does not need to be widened before it is slid onto the outer support section of the outer fitting body, since sufficient sealing can be achieved by the fitting according to the invention without the restoring forces, for example of a previously widened tubular end comprising plastic, being necessary. 5 In particular, thick connections are therefore possible, the tubular end being the end of a connecting tube, in particular of a composite or multilayer composite connecting tube, preferably a composite or multilayer composite tube comprising plastic. In particular, the latter comprises a plastic as the inner layer. [0 The composite or multilayer composite tube may, in particular, comprise one or more layers of plastic and metal. The following plastics may be used in this case: crosslinked polyethylene (PE-Xa, PE-Xb, PE-Xc), polyvinylidene fluoride (PVDF), non-crosslinked polyethylene (PE-RT), polybutene and/or polypropylene. Crosslinked polyethylene (PE 15 Xa, PE-Xb, PE-Xc) is preferably used as the inner layer in this case. The composite or multilayer composite tube may, however, also comprise one or more inner-lying layers of metal, in particular copper, brass, aluminium and/or steel, in particular ferritic or austenitic stainless steel, or an alloy or combination thereof. 20 There are now a plurality of possibilities for configuration and refinement of the invention. In this regard, on the one hand, reference is made to the patent claims dependent on the independent patent claims, and in addition the invention will be explained in more detail with the aid of the following exemplary embodiments. 25 Reference is made to the appended drawing. In the drawing: Fig. 1 shows a first exemplary embodiment of a system according to the invention 30 having a first exemplary embodiment of a fitting according to the invention and an outer sleeve, in longitudinal section; - 12 Fig. 2 shows a second exemplary embodiment of a system according to the invention having a second exemplary embodiment of a fitting according to the invention and an outer sleeve, in combination with a further fitting system, in longitudinal section; 5 Fig. 3 shows a third exemplary embodiment of a system according to the invention having a third exemplary embodiment of a fitting according to the invention and an outer sleeve comprising a union nut, in longitudinal section. 10 Fig. 1 shows a first exemplary embodiment of a system 1 according to the invention having a first exemplary embodiment of a fitting 2 according to the invention and an outer sleeve 4, in longitudinal section. The fitting 2 comprises an outer tubular fitting body 6, which has an outer support section 8 and a base section 10. The fitting 2 furthermore comprises an inner tubular fitting body 12, which has an inner support 15 section 14 and a base section 16. The outer fitting body 6 in this case consists entirely of PPSU, although other plastics may also be used. The inner fitting body 12 consists in this case entirely of copper, although other metals may also be used here. The fitting bodies 6, 12 can be inserted into the tubular end with their ends 6a, 12a that 20 face towards the tubular end 18. In this case, in contrast to the base bodies 10, 16, only the support sections 8, 14 can be inserted into the tubular end 18. The tubular end is in this example that of a multilayer composite tube having three layers 18a, 18b, 18c. In particular, the inner layer 18c is made of crosslinked polyethylene (PE-Xa, PE-Xb, PE Xc), the middle layer 18b is made of aluminium and the outer layer 18a is made of 25 conventional polyethylene (PE) as a protective layer. The inner fitting body 12 is arranged essentially coaxially inside the outer fitting body 6, so that the inner support section 14 is also arranged essentially coaxially inside the outer support section 6 along the common longitudinal axis A. The inner fitting body 12 30 is in this case inserted partially with oversize into the outer fitting body 6. Particularly in the region of the regions 24a and 24b, this locally leads to a force-fit connection in the - 13 form of a press fit between the inner circumferential surface 20 of the outer support section 6 and the outer circumferential surface 22 of the inner support section 12. As a result, the inner circumferential surface 20 of the outer support section 6 and the outer circumferential surface 22 of the inner support section 12 are sealed against one 5 another in sections, in the present case in the sections 24a and 24b. Between the sections 24a and 24b sealed in this way between the inner and outer fitting bodies 6, 12, a cavity 28a is formed between the inner circumferential surface 20 of the outer support section 6 and the outer circumferential surface 22 of the inner support 10 section 12. The cavity 28a, which in this case is annularly circumferential, is formed by a likewise annularly circumferential recess in the inner circumferential surface 20 of the outer support section 8. The cavity 28a is filled with air, and has a longitudinal extent in the longitudinal axial direction. As a result of the sealed sections 24a and 24b, the cavity 28a lying between them is sealed from the environment and from the interior of the 15 conduit. In the region of the cavity 28a, a radially outward elevation in the form of a serration 32a is provided on the outer circumferential surface 30 of the outer support section 8. The serration 32a is configured in the shape of a barb, so that the tubular end 18 is 20 prevented from sliding out. The serration leads to effective sealing with the inner circumferential surface of the inserted tubular end 18. Owing to the fact that the radially outward elevation 32a is provided in the region of the cavity 28a, the outer support section 8 can bend into the cavity 28a in this region. As a result of the hoop forces and the bending forces, the serration 32 can be sealed against the tubular end 18 after the 25 tubular end 18 has been slid onto the outer support section 8 and onto the serration 32a. The outer support section 8 can also participate in possible resiliences of the tubular end 18 owing to the cavity 28a. The outer circumferential surface 30 of the outer support section 8 has a further radially 30 outward elevation in the form of a serration 32b in the region of the end 6a of the fitting body 6 facing towards the tubular end 18. The serration 32b is formed essentially like - 14 the serration 32a, although different configurations may also be selected. Since the end 6a of the outer support section 8 facing towards the tubular end 18 extends beyond the end 12a of the inner support section 14 facing towards the tubular end 18 in the axial direction, the outer support section 8 and the inner support section 14 do not in this 5 case overlap in the radial direction, so that a region freely bending inwards is formed in the region of the further serration 32b on the end 6a of the outer support section 8 facing towards the tubular end 18. In this region, the outer support section 8 can seal the tubular end 18 like a fitting made entirely of plastic. The wall thickness of the outer support section 8 is at least partially increased in this region relative to that of the rest 10 of the outer support section 8. In this way, a stop 34 for the inner fitting body 12 in the axial direction is furthermore formed on the inner circumferential surface of the outer support section. The outer fitting body 6 has a flange section 36 extending radially outwards on its base 15 section 10. This is used as a stop in the axial direction for the outer sleeve 4. Furthermore, the flange section 36 can facilitate handleablility during mounting, particularly when the tubular end 18 is being slid on. The outer sleeve 4 is essentially configured cylindrically and is arranged essentially 20 coaxially with the fitting bodies 6, 12, or the axis A. The outer sleeve consists of metal in this exemplary embodiment, although other materials such as plastic may also be used as an alternative. An annularly circumferential recess 40 is formed between the inner circumferential surface 38 of the outer sleeve 4 and the outer circumferential surface 30 of the outer support section 6. The tubular end 18 is inserted into the recess 40 in order 25 to produce a sealed connection. In order to facilitate the insertion of the tubular end 18, the outer sleeve 4 is curved radially outwards at its end facing towards the tubular end 18. Conversely, the outer sleeve is curved radially inwards at its end facing away from the tubular end 18, in order to provide a contact surface with the flange section 36. The outer sleeve 4 furthermore has recesses 42 in order to check the positioning of the 30 tubular end 18. By providing the outer sleeve 4, a radially inward force can be exerted - 15 on the tubular end 18 in the region of the inner or outer support section 8, 14 in the inserted state. The end of the inner fitting body 12 facing away from the tubular end 18 extends beyond 5 the end of the outer fitting body 6 facing away from the tubular end in the axial direction. The base section 16 adjacent to the inner support section 14 of the inner fitting body 12 may in this case continue essentially cylindrically. Nevertheless, any desired configuration may be provided on the end of the inner fitting body 12 facing away from the tubular end 18. In particular, the inner fitting body 12 may be configured 10 in such a way that further components, such as fitting bodies or fittings, can be connected thereto. As can be seen in Fig. 1, no sealing ring or sealing element is required for sealed connection of the tubular end of the multilayer composite tube comprising PEX. 15 Nevertheless, the tubular end 18 can be slid onto the fitting 2 comprising an inner fitting body 12 made of metal, without being widened, and a sealed connection can thus be produced in the sections 32a and 32b. The fitting can therefore be used in particular both for gas and for water or drinking water conduits. 20 Fig. 2 shows a second exemplary embodiment of a system 1 according to the invention having a second exemplary embodiment of a fitting 2 according to the invention and an outer sleeve 4 in combination with a further fitting system 1', in longitudinal section. Since the system 1 in Fig. 2 is similar to that of Fig. 1, corresponding parts of the second 25 exemplary embodiment of the system 1 are provided with the same numerals. Fig. 2 furthermore represents the way in which the fitting 2 is connected on the left hand side to a further fitting system 1', not configured according to the invention described above. This is likewise constructed similarly to the system 1. In this case, 30 corresponding parts are provided with dashed numerals.

- 16 In contrast to the fitting 2 represented in Fig. 1, the fitting 2 represented in Fig. 2 has an inner support section 14 extending longer in the axial direction. The inner support section 14 and the outer support section 18 therefore still overlap in the region of the further radially outward elevation in the form of the serration 32b. In order to allow a 5 similar elasticity in the region of the serration 32b compared with the region freely bending inwards on the end 6a of the outer support section 8 facing towards the tubular end 18, as shown in Fig. 1, a cavity 28b is also provided in the region of the serration 32b, as in the region of the serration 32a. In contrast to the fitting represented in Fig. 1, the cavities 28a, 28b are produced by providing recesses on the outer circumferential 10 surface 22 of the inner support section 14. In this exemplary embodiment, however, the end 6a of the outer support section 8 facing towards the tubular end 18 extends beyond the end 12a of the inner support section 14 facing towards the tubular end 18 in the axial direction. This gives a total of 3 sections 24a, 24b, 24c in which the outer support section 8 is sealed against the inner support section 14 by means of a press fit. The 15 cavities 28a, 28b lie between the sections 24a, 24b, 24c. It is, however, also possible to select a different arrangement of this region. In particular, a different number of cavities 28a, 28b and sections 24a, 24b, 24c may be selected. A further difference is that the flange section 36 is provided as a separate part from the 20 base section 10 of the outer fitting body. The flange section 36 consists of the same material as the outer fitting body 6, although other materials may also be used. The flange section 36 has a latch projection 44, while the base section 10 has a corresponding latch indentation 46 on the outer circumferential surface, in order to achieve axial fixing of the flange section 36 relative to the outer fitting body 6. The flange 25 section 36 furthermore has a recess 48 to receive the end of the outer sleeve 4 facing away from the tubular end 18. In contrast to the outer sleeve represented in Fig. 1, the outer sleeve 4 shown in Fig. 2 furthermore has a fixing projection 50 for fixing the tubular end 18. Naturally, a plurality 30 of such projections may also be provided.

- 17 The base section 16 of the inner fitting body 12 is followed, as shown on the left-hand side in Fig. 2, by a further inner base section 16' of the inner fitting body 12. In the inner base section 16', the inner fitting body 12 experiences two reductions in cross-section, so that an outer fitting body 6' with an outer sleeve 4' having a smaller diameter in 5 comparison with the fitting body 6 and the outer sleeve 4 can be connected. Thus, a tubular end having a smaller cross section can be connected on the left-hand side. A symmetrical configuration is also possible, however, so that the fitting system 1' may also be configured according to the invention. 10 In the present case, although the system 1' is constructed similarly to the system 1 of Fig. 1 or 2, there is however only one outer support section 8'. There is no overlap in the radial direction of the outer support section 8' with an inner support section. The inner support section 8' serves here as a support section made entirely of plastic. Correspondingly, the wall thickness of the inner support section 8' is also selected to be 15 thicker than that of the support section 8. The sealed connection between the base section 16' and the base section 10' of the outer fitting body 6' is again produced by a press fit. Fig. 3 shows a third exemplary embodiment of a system 1 according to the invention 20 having a third exemplary embodiment of a fitting 2 according to the invention and an outer sleeve 4, in longitudinal section. The tubular end 18 is not shown. The fitting 2 is very similar to that of Fig. 2. In Fig. 3, however, the flange region 36 of the base section 10 of the outer support body 6 differs from that shown in Fig. 2. The flange region 38 has means 52 for connection to the outer sleeve 4, which in this exemplary embodiment is 25 formed in two parts and comprises the union nut 4a and the clamping body 4b. The union nut 4a and the flange region are connected here by means of a screw thread 52. The screw thread 52 is undercut with the recess 36a in the flange section 36. When the union nut 4a is screwed onto the screw thread 52 of the flange region, the clamping body 4b is therefore pressed essentially radially inwards against the outer 30 circumferential surface of a tubular end 18 inserted into the annularly circumferential recess 40 owing to the inner circumferential surface 38a of the union nut 4a configured - 18 obliquely with respect to the axial direction A and the outer circumferential surface, adapted thereto, of the clamping body 4b. The inner circumferential surface 38b of the clamping body 4b in this case has a profiling in form of the fixing projections 50. 5 The tubular end 18 inserted into the recess 40 therefore cannot slip down from the fitting 2 and be pressed against the outer circumferential surface 30 of the outer support body, or against radially outward elevations 32a, 32b which are provided, in order to produce a particularly reliable and sealed connection.

Claims

1. Fitting for sealed connection to a tubular end (18), in particular of a tube, - having an outer tubular fitting body (6) and - having an inner tubular fitting body (12), 5 - wherein the outer fitting body (6) comprises an outer support section (8), consisting at least partially of plastic, for insertion into the tubular end (18), - wherein the inner fitting body (12) comprises an inner support section (14), consisting at least partially of metal, for insertion into the tubular end (18), - wherein the inner support section (12) is at least partially arranged inside the t0 outer support section (6), - wherein the inner circumferential surface (20) of the outer support section (6) and the outer circumferential surface (22) of the inner support section (12) are sealed against one another in sections (24a, 24b, 24c), and - wherein at least one cavity (28a, 28b) is formed between the inner i5 circumferential surface (20) of the outer support section (6) and the outer circumferential section surface (22) of the inner support section (12).

2. Fitting according to Claim 1, characterised in that 20 at least one radially outward elevation (32a, 32b) is provided on the outer circumferential surface (30) of the outer support section (6), particularly in the form of a profiling, which is arranged at least partially in the region of the at least one cavity (28a, 28b). 25

3. Fitting according to Claim 1 or 2, characterised in that at least one cavity (28a, 28b) between the inner circumferential surface (20) of the outer support section (6) and the outer circumferential surface (22) of the - 20 inner support section (12) is an air-filled, preferably annularly circumferential cavity (28a, 28b).

4. Fitting according to any one of Claims 1 to 3, 5 characterised in that at least one cavity (28, 28b) between the inner circumferential surface (20) of the outer support section (6) and the outer circumferential surface (22) of the inner support section (12) is formed by at least one recess on the outer circumferential surface (22) of the inner support section (12) and/or the inner circumferential [0 surface (20) of the outer support section (6).

5. Fitting according to any one of Claims 1 to 4, characterised in that the inner circumferential surface (20) of the outer support section (6) and the [5 outer circumferential surface (22) of the inner support section (12) are sealed against one another in sections by means of a force-fit connection, in particular a press fit.

6. Fitting according to any one of Claims 1 to 5, 20 characterised in that the fitting (2) is configured without a sealing ring, in particular without a sealing element.

7. Fitting according to any one of Claims 1 to 6, 25 characterised in that the end (6) of the outer support section (6a) facing towards the tubular end (18) extends beyond the end (12a) of the inner support section (12) facing towards the tubular end (18) in the axial direction. 30 - 21

8. Fitting according to any one of Claims 1 to 7, characterised in that the end of the inner fitting body (12) facing away from the tubular end (12) extends beyond the end of the outer fitting body (6) facing away from the tubular 5 end (18) in the axial direction.

9. Fitting according to any one of Claims 1 to 8, characterised in that the inner fitting body (12), in particular the inner support section (14), consists [0 at least partially of copper, brass, aluminium and/or steel, in particular ferritic or austenitic stainless steel, or an alloy or combination thereof.

10. Fitting according to any one of Claims 1 to 9, characterised in that [5 the outer fitting body (6), in particular the outer support section (8), consists at least partially of polyphenyl sulfone (PPSU), polyvinylidene fluoride (PVDF), non crosslinked polyethylene (PE-RT), crosslinked polyethylene (PE-Xa, PE-Xb, PE Xc), polybutene and/or polypropylene. 20

11. System - having a fitting (2) according to any one of Claims 1 to 10, and - having an outer sleeve (4), - wherein an annularly circumferential recess (40) for the tubular end (18) to be connected is formed between the inner circumferential surface (38) of the outer 25 sleeve (4) and the outer circumferential surface (30) of the outer support section (6). - 22

12. System according to Claim 11, characterised in that the outer sleeve (4) is connected directly or indirectly to the inner and/or the outer fitting body (6), in particular to a base section (10) adjoining the outer 5 support section (8) of the outer fitting body (6).

13. Sealed connection, - having a fitting (2) according to any one of Claims 1 to 10, and - having a tubular end (18), t0 - wherein the tubular end (18) is positioned on the outer support section (8) of the outer fitting body (6).

14. Sealed connection according to Claim 13, characterised in that the tubular end (18) is the end of a composite tube, in [5 particular of a multilayer composite tube.