Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
CONNECTION ASSEMBLY FOR TUBULAR ELEMENTS, IN PARTICULAR FOR HEAT EXCHANGERS, BUSHING INCLUDED IN SAID ASSEMBLY AND HEAT EXCHANGER INCLUDING SAID BUSHING
Document Type and Number:
WIPO Patent Application WO/2014/199359
Kind Code:
A2
Abstract:
The present invention relates to a connection assembly (1) for reversibly connecting in a sealing manner a first female tubular element (10) made of a first metallic material to a second male tubular element (12) made of a second metallic material different from the first material, comprising: a) at least one flange (10b) radially extending from the first (10) and/or from the second (12) tubular element; b) a coupling element (30) made of plastic of the tubular elements (10, 12) comprising a fork-shaped body (30a) configured to axially cooperate with the end portions of the tubular elements (10, 12) at the flange (10b) so as to prevent a reciprocal axial sliding of the tubular elements (10, 12); c) a bushing (20) made of plastic reversibly coupled in a sliding manner within the end portion of the first female tubular element (10) and comprising a substantially cylindrical body (21) associated to a radially inner wall of the end portion of the first female tubular element (10) and configured so as to receive in a sliding manner and with substantial shape coupling a free end portion of the second male tubular element (12); d) at least a first radial sealing element (22, 24) associated to a radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) and configured so as to cooperate in a sealing manner with a radially inner wall (10a) of the end portion of the first female tubular element (10); and e) at least a second radial sealing element (14) arranged between an end portion of the second male tubular element (12) and a radially inner wall (21b) of the substantially cylindrical body (21) of the bushing (20). The present invention also relates to the bushing (20) included in such a connection assembly (1) and to a heat exchanger (5) provided with a tubular joining element (10) including such a bushing (20).

Inventors:
GERMINIASI, Massimo (VIa Luna 24, Marudo LO, I-26866, IT)
Application Number:
IB2014/062269
Publication Date:
December 18, 2014
Filing Date:
June 16, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
CONDEVO S.P.A. (Via Giacomo Leopardi 20, Milano, I-20123, IT)
International Classes:
F16L25/00; F16L25/02; F16L37/12; F16L37/14
Foreign References:
JP2012107683A2012-06-07
JP2010151305A2010-07-08
US4524995A1985-06-25
JP2008240984A2008-10-09
Attorney, Agent or Firm:
BOTTERO, Claudio et al. (Via Trebbia 20, Milano, I-20135, IT)
Download PDF:
Claims:
CLAIMS

1. Connection assembly (1) for reversibly connecting in a sealing manner a first female tubular element (10) made of a first metallic material to a second male tubular element (12) made of a second metallic material different from said first material, wherein the connection assembly (1) comprises: a) at least one flange (10b) radially extending from a respective end portion of at least one of said first (10) and second (12) tubular element; b) a coupling element (30) made of plastic material of said first (10) and second (12) tubular element, said coupling element (30) comprising a fork-shaped body (30a) configured so as to axially cooperate with the end portions of said first (10) and of said second (12) tubular element at said at least one flange (10b) so as to prevent a reciprocal axial sliding of the first (10) and of the second (12) tubular element; and c) a bushing (20) made of plastic comprising a substantially cylindrical body (21) associated to a radially inner wall (10a) of the end portion of the first female tubular element (10), said substantially cylindrical body (21) being configured so as to slidably receive with substantial shape coupling a free end portion of the second male tubular element (12); characterised in that said bushing (20) is reversibly coupled in a sliding manner within the end portion of the first female tubular element (10) and in that the connection assembly (1) further comprises: d) at least a first radial sealing element (22, 24) associated to a radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) and configured so as to cooperate in a sealing manner with a radially inner wall (10a) of said end portion of the first female tubular element (10); and e) at least a second radial sealing element (14) arranged between an end portion of the second male tubular element (12) and a radially inner wall (21b) of the substantially cylindrical body (21) of the bushing (20).

2. Connection assembly (1) according to claim 1, wherein said bushing (20) comprises a flange (20c) outwardly radially extending from a free end of said substantially cylindrical body (21) facing the second male tubular element (12).

3. Connection assembly (1) according to claim 2, wherein said flange (20c) of the bushing (20) abuts against said at least one flange (10b) radially extending from a respective end portion of at least one of said first (10) and second (12) tubular element.

4. Connection assembly (1) according to claim 3, wherein said flange (20c) of the bushing (20) abuts against a flange (10b) radially extending from a free end of the first female tubular element (10). 5. Connection assembly (1) according to claim 1, wherein said bushing (20) comprises a pair of first radial sealing elements (22, 24) axially spaced apart from one another and associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20).

6. Connection assembly (1) according to claim 5, wherein one of said first radial sealing elements (22, 24) is associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) at a free end of said body (21) that is arranged axially more inwardly with respect to the end portion of the first tubular element (10).

7. Connection assembly (1) according to claims 5 or 6, wherein one of said first radial sealing elements (22, 24) is associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) at a free end of said body that is arranged axially more outwardly with respect to the end portion of the first tubular element (10).

8. Connection assembly (1) according to any one of claims 1-7, wherein said at least a first radial sealing element (22, 24) is comoulded or overmoulded on the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20).

9. Connection assembly (1) according to any one of claims 1-8, wherein the substantially cylindrical body (21) of the bushing (20) is provided with a respective housing seat of said at least a first radial sealing element (22, 24).

10. Connection assembly (1) according to claim 9, wherein the housing seat of said at least a first radial sealing element (22, 24) is provided with an annular projection (21e) configured to cooperate with said at least a first radial sealing element (22, 24).

11. Connection assembly (1) according to claims 5 and 8, wherein the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) comprises a plurality of substantially axial grooves (2 If). 12. Connection assembly (1) according to claim 1, wherein said at least a second radial sealing element (14) is associated to a radially outer wall (12a) of the second male tubular element (12).

13. Connection assembly (1) according to claim 12, wherein said at least a second radial sealing element (14) is removably received in a respective housing seat (12d) formed at an end portion of the second male tubular element (12).

14. Connection assembly (1) according to claim 1, wherein said bushing (20) is internally provided with a stop element (15) configured to cooperate in abutment relationship with a free end of the second male tubular element (12).

15. Connection assembly (1) according to any one of claims 1-11, wherein the fork- shaped body (30a) of said coupling element (30) comprises a pair of opposite shaped arms (30b) each provided with: - at least one substantially arc-shaped central portion configured to receive with substantial shape coupling the respective end portions of said first and of said second tubular element, and with

- a central slot (30g) extending in the substantially arc-shaped central portion of each shaped arm (30b) and configured to receive said at least one flange (10b) radially extending from at least one of said first (10) and second (12) tubular element and, if present, from said flange (20c) of the bushing (20).

16. Connection assembly (1) according to claim 15, wherein the central portion of each of said shaped arms (30b) comprises a pair of half-portions (30c; 30d) extending at axially opposite sides of said central slot (30g), each of said half-portions (30c; 30d) being configured to: i) receive with substantial shape coupling a respective end portion of said first (10) and of said second (12) tubular element, respectively; and ii) radially cooperate with said respective end portion so as to grip the same; at least one of said half-portions (30c; 30d) being further provided with a slot-side edge (30e; 30f) configured so as to axially cooperate with said at least one flange (10b) radially extending from at least one of said first (10) and second (12) tubular element, said edge (30e; 30f) forming a stop element against the reciprocal axial sliding of said first (10) and second (12) tubular element.

17. Connection assembly (1) according to claim 15, wherein: the end portion of the second male tubular element (12) comprises at least one annular projection (12e), said annular projection (12e) having an outer diameter substantially equal to the inner diameter of the substantially cylindrical body (21) of the bushing (20); and wherein the substantially arc-shaped central portion of each of the shaped arms (30b) of the fork- shaped body (30a) of the coupling element (30) comprises: a) a first half-portion (30c) provided with a slot-side edge (3 Of) configured so as to axially cooperate with a flange (10b) radially extending from the free end of said first female tubular element (10), and b) a second half-portion (30d) provided with a slot-side edge (30e) configured so as to axially cooperate with said annular projection (12e) of the second male tubular element (12), said slot-side edges (30e; 30f) of the first (30c) and second (30d) half-portion of the shaped amis (30b) of the fork-shaped body (30a) forming said stop element against the reciprocal axial sliding of said first (10) and second (12) tubular element.

18. Connection assembly (1) according to any one of claims 15-17, wherein the central slot (30g) extending in the central portion of each shaped arm (30b) has a width substantially equal to the axial thickness of said at least one flange (10b) radially extending from a respective end portion of at least one of said first (10) and second (12) tubular element or to the axial thicloiess of said at least one flange (10b) and of the flange (20c) of the bushing (20), if present. 19. Connection assembly (1) according to any one of claims 15-18, wherein the shaped arms (30b) of the fork- shaped body (30a) of the coupling element (30) comprise a free end portion (30i) outwardly inclined with respect to said substantially arc-shaped central portion.

20. Connection assembly (1) according to any one of the preceding claims, wherein said first female tubular element (10) comprises a tubular joining element of a duct of a heat exchanger (5).

21. Connection assembly (1) according to claim 20, wherein said at least one tubular joining element comprises a socket joint.

22. Connection assembly (1) according to any one of the preceding claims, wherein said first metallic material is aluminium or alloys thereof.

23. Connection assembly (1) according to any one of the preceding claims, wherein said second male tubular element (12) comprises an end portion of a pipe of a hydraulic circuit of a water-heating apparatus or of an air-conditioning apparatus.

24. Connection assembly (1) according to any one of the preceding claims, wherein said second metallic material is copper or alloys thereof. 25. Heat exchanger (5) comprising at least one heat exchange section (7) and at least one pair of fluid inlet/outlet ducts (9) from said section, at least one of said ducts (9) being provided with a tubular joining element (10) made of a first metallic material and configured so as to receive an end portion of a pipe (12) of an external hydraulic circuit made of a second metallic material different from said first metallic material, characterised in that it comprises at least one bushing (20) made of plastic comprising a substantially cylindrical body (21) associated to a radially inner wall (10a) of an end portion of said tubular joining element (10) of said at least one duct (9) of the heat exchanger (5), said substantially cylindrical body (21) being configured so as to receive in a sliding manner and with substantial shape coupling a free end portion of said pipe (12) of the external hydraulic circuit, and in that said bushing (20) is reversibly coupled in a sliding manner within the end portion of said tubular joining element (10) and comprises at least a radial sealing element (22, 24) associated to a radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) and configured so as to cooperate in a sealing manner with said radially inner wall (10a) of the end portion of the tubular joining element (10).

26. Heat exchanger (5) according to claim 25, wherein said tubular joining element (10) comprises a flange (10b) radially extending from a free end thereof.

27. Heat exchanger (5) according to claim 26, wherein said bushing (20) comprises a flange (20c) outwardly radially extending from a free end of said substantially cylindrical body (21) and configured to abut against said flange (10b) of said tubular joining element (10) of the exchanger (5).

28. Heat exchanger (5) according to claim 25, wherein said bushing (20) comprises a pair of radial sealing elements (22, 24) axially spaced apart from one another and associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20).

29. Heat exchanger (5) according to claim 28, wherein one of said radial sealing elements (22, 24) is associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) at a free end of said body (21) that is arranged axially more inwardly with respect to the end portion of the tubular joining element (10) of the heat exchanger (5).

30. Heat exchanger (5) according to claims 28 or 29, wherein one of said radial sealing elements (22, 24) is associated to the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) at a free end of said body that is arranged axially more outwardly with respect to the end portion of the tubular joining element (10) of the heat exchanger (5).

31. Heat exchanger (5) according to any one of claims 25-30, wherein said at least one radial sealing element (22, 24) is comoulded or overmoulded on the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20).

32. Heat exchanger (5) according to any one of claims 25-31, wherein the substantially cylindrical body (21) of the bushing (20) is provided with a respective housing seat of said at least a radial sealing element (22, 24).

33. Heat exchanger (5) according to claim 32, wherein the housing seat of said at least a radial sealing element (22, 24) is provided with an annular projection (21e) configured to cooperate with the radial sealing element (22, 24).

34. Heat exchanger (5) according to claims 28 and 31, wherein the radially outer wall (21a) of the substantially cylindrical body (21) of the bushing (20) comprises a plurality of substantially axial grooves (2 If). 35. Heat exchanger (5) according to any one of claims 25-34, wherein said bushing (20) is internally provided with a stop element (15) configured to cooperate in abutment relationship with a free end of the second male tubular element (12).

36. Heat exchanger (5) according to any one of claims 25-35, wherein said tubular joining element (10) comprises a socket joint. 37. Heat exchanger (5) according to any one of claims 25-36, wherein said first metallic material is aluminium or alloys thereof.

38. Bushing (20) made of plastic for use in a connection assembly (1) configured so as to reversibly comiect in a sealing manner a first female tubular element (10) made of a first metallic material to a second male tubular element (12) made of a second metallic material different from said first metallic material, said bushing (20) comprising: a) a substantially cylindrical body (21) configured so as to: i) cooperate in a sliding manner and with shape coupling with a radially inner wall (10a) of an end portion of said first female tubular element (10), and ii) receive in a sliding manner and with substantial shape coupling a free end portion of the second male tubular element (12), and b) at least a radial sealing element (22, 24) associated to a radially outer wall (21a) of said substantially cylindrical body (21) and configured so as to cooperate in a sealing manner with a radially inner wall (10a) of said end portion of the first female tubular element (10).

39. Bushing (20) according to claim 38, further comprising a flange (20c) outwardly radially extending from a free end of said substantially cylindrical body (21).

40. Bushing (20) according to claim 38, comprising a pair of radial sealing elements (22, 24) axially spaced apart from one another and associated to the radially outer wall (21a) of said substantially cylindrical body (21).

41. Bushing (20) according to claim 38 or 40, wherein one of said radial sealing elements (22, 24) is associated to the radially outer wall (21a) of said substantially cylindrical body (21) at a first free end of said body (21).

42. Bushing (20) according to any one of claims 38-41, wherein one of said radial sealing elements (22, 24) is associated to the radially outer wall (21a) of said substantially cylindrical body (21) of the bushing (20) at a second free end of said body (21).

43. Bushing (20) according to any one of claims 38-42, wherein said at least one radial sealing element (22, 24) is comoulded or overmoulded on the radially outer wall (21a) of said substantially cylindrical body (21).

44. Bushing (20) according to any one of claims 38-43, wherein said substantially cylindrical body (21) is provided with a respective housing seat of said at least one radial sealing element (22, 24).

45. Bushing (20) according to claim 44, wherein the housing seat of said at least a radial sealing element (22, 24) is provided with an annular projection (21e) configured to cooperate with the radial sealing element (22, 24). 46. Bushing (20) according to claim 43 when dependent on claim 40, wherein the radially outer wall (21a) of said substantially cylindrical body (21) comprises a plurality of substantially axial grooves (2 If).

47. Bushing (20) according to any one of claims 38-46, wherein the bushing (20) is internally provided with a stop element (15) configured to cooperate in abutment relationship with a free end of the second male tubular element (12).

Description:
CONNECTION ASSEMBLY FOR TUBULAR ELEMENTS, IN PARTICULAR FOR HEAT EXCHANGERS, BUSHING INCLUDED IN SAID ASSEMBLY AND HEAT EXCHANGER INCLUDING SAID BUSHING

DESCRIPTION Field of the invention

The present invention concerns in general the field of hydraulic connections and, more specifically, it relates to a connection assembly for reversibly connecting in a sealing manner a first female tubular element made of a first metallic material to a second male tubular element made of a second metallic material different from said first material. The present invention also relates to a bushing made of plastic included in such a connection assembly and to a heat exchanger comprising at least one heat exchange section and at least one pair of fluid inlet/outlet ducts from said section, at least one of said ducts being provided with a tubular joining element made of a first metallic material and including the aforementioned bushing made of plastic. Related art

In the field of hydraulic connections between pipes, it has been observed that when they are made of different metallic materials phenomena of galvanic corrosion at the surfaces in mutual contact (related to the difference in electrochemical potential between the two metallic materials in contact) may arise, which phenomena reduce the reliability of the connection itself with the consequent need of arranging a periodic maintenance.

A field in which these galvanic corrosion phenomena are particularly unwanted is that of water-heating apparatuses or air-conditioning apparatuses incorporating at least one heat exchanger whenever the latter is made of a material different from that of the external hydraulic circuit which the heat exchanger is connected to. Nowadays, this circumstance increasingly often occurs in light of the market tendency to make the aforementioned heat exchangers of aluminium or alloys thereof, a material which has the advantageous feature of having a good heat conductivity coupled to a relatively low cost, instead of making the heat exchangers of copper as is traditionally the case. The Applicant has found that in these cases phenomena of galvanic corrosion occur due to the difference in electrochemical potential between aluminium and copper at the coupling between a tubular joining element of the heat exchanger and the pipe of the external hydraulic circuit, which corrosion phenomena may possibly lead in time to leakages.

The latter require an unplanned maintenance intervention that the manufacturers of water-heating or air-conditioning apparatuses aim for obvious reasons to greatly reduce if not entirely eliminate.

In order to cany out a connection between a first female tubular element and a second male tubular element, joining devices or assemblies are known in the art which comprise at least a pair of flanges radially extending from respective end portions of the tubular elements and a coupling element comprising a fork-shaped body configured to axially cooperate with the flanges of the tubular elements so as to prevent a reciprocal axial sliding of the latter.

Thus, document JP 2012/107683 discloses a cylindrical coupling element made of a synthetic resin that is interposed between a male tubular element, made of a metallic material, and a female tubular element. The cylindrical coupling element is irreversibly associated by moulding to a radially outer wall of the male tubular element which is suitably equipped with anchoring projections radially extending from an end portion of such an element. The male tubular element is then coupled to the female tubular element by partially inserting the cylindrical coupling element into the latter. Thereafter, the connection between the tubular elements is completed by arranging a fork-shaped coupling element, made of metallic material, astride a flange of the female tubular element and a flange-forming portion of the cylindrical coupling element (which is not inserted into the female tubular element), so as to prevent the reciprocal axial sliding between the tubular elements.

Document JP 2010/151305 discloses a coupling between a female tubular element and a male tubular element having a composite structure with three layers comprising an inner layer of synthetic resin, having a major thickness, externally coated by a thin layer of aluminium, which is in turn externally coated by an additional layer of synthetic resin. A flange in two pieces is externally associated to the male tubular element at a predetermined distance from the free end portion of such a male tubular element that is thus outside of the flange itself, making an anchoring groove intended to receive and hold a semi-circular projection formed at a free end of each piece of the flange. In this way, the body of the assembled flange is configured to lock the flange on the male tubular element preventing any relative sliding movement between the flange and the male tubular element. A metallic reinforcement sleeve is inserted in the free end portion of the male tubular element to reinforce said element at the aforementioned groove. Also in this case, the connection between the tubular elements is completed by arranging a fork-shaped coupling element astride the flange associated to the male tubular element and a flange of the female tubular element so as to prevent the reciprocal axial sliding between the tubular elements. US patent 4,524,995 discloses a swivelable quick-connect assembly for use with tubular conduits, comprising a housing having an axial bore to receive an end of a duct, an elastomeric annular gasket disposed in the bore to provide a fluid-tight seal between confronting portions of the conduit and the housing, an annular bushing disposed in the bore for positioning the gasket and for guiding an end of the duct into nesting relationship with the bore, and a retainer removably secured to the housing and adapted to cooperate with an annular projection on the conduit for securing the conduit in its operative position within the bore. The retainer is in turn provided with resilient defomiable portions which are adapted to snap over the locking wall upon insertion of the conduit into the housing bore. Document JP 2008-240984 discloses a pipe connection structure comprising a female tubular element provided with a flange, a male tubular element inserted in the end part of the female tubular element and having a sleeve externally associated at a predetermined distance from the free end portion of such a male tubular element, and a stopper having two supporting pieces axially cooperating with the flange of the female tubular element and the sleeve of the male tubular element so as to prevent a reciprocal axial sliding between the tubular elements.

Summary of the invention

The Applicant has found that the joining devices disclosed in documents JP 2012/107683, JP 2010/151305 and JP 2008-240984 possess the drawback of requiring a specific preparation of the male tubular element before coupling with onerous processing in terms of costs and time. In fact, in the case of JP 2012/107683 it is necessary to provide suitable anchoring projections on the male tubular element and carry out suitable moulding processing of the cylindrical coupling element irreversibly associated to such a tubular element, whereas in the case of JP 2010/151305 it is necessary to separately manufacture two additional elements, i.e. the flange associated to the male tubular element and the metallic reinforcing sleeve of such a tubular element and, also, to cany out a specific processing of its end portion to form a suitable groove necessary for accomplishing a coupling with the aforementioned flange.

Similar considerations apply for the pipe connection structure described by JP 2008- 240984 for which it is necessary to separately manufacture an additional element, i.e. the sleeve externally associated to the male tubular element and, also, to cany out a specific processing of its end portion to form a suitable projection necessary for accomplishing a coupling with the aforementioned sleeve.

The Applicant has also found that the coupling device described in document JP 2010/151305 involves high costs and substantial constructive complication since it presupposes - in order to ensure the desired absence of contact between different kinds of metallic materials in the connection area with the female tubular element - the use of a male tubular element having a composite three-layer structure having a relatively high cost, in association with the aforementioned reinforcing sleeve of the tubular element (an additional element which further increases the costs).

The Applicant has also found that by using the coupling devices disclosed in the aforementioned prior art documents undesired fluid leakages may occur after a certain time, in particular between the cylindrical coupling element, flange, annular bushing or sleeve inserted in the end portion of the female tubular element and the inner wall of the female tubular element and/or the outer wall of the male tubular element.

The Applicant has in particular found that the way of irreversibly connecting the substantially cylindrical body of the annular bushing to the radially inner wall of the end portion of the female tubular element envisaged by the connection assembly disclosed by US 4,524,995, irreversible connection which is generally obtained by gluing or moulding, can present in time the drawback of being subject to fluid leakages, especially in the case of hot fluids, due to the formation of ageing cracks in the layer of adhesive or at the interface between the plastic of the bushing and the metallic material of the female tubular element.

Equally, the Applicant has found that the way of irreversibly connecting by moulding of a synthetic resin of the cylindrical coupling element disclosed by JP 2012/107683 on the end portion of the male tubular element involve similar leaking problems upon ageing at the interface between the synthetic resin of the cylindrical coupling element and the metallic material of the male tubular element.

The problem underlying the invention is therefore that of overcoming the aforementioned drawbacks, in particular by providing a connection assembly configured so as to reversibly connect in a sealing manner a first female tubular element made of a first metallic material to a second male tubular element made of a second metallic material different from said first metallic material, which allows to accomplish a connection which does not trigger in time undesired corrosion problems linked to the formation of galvanic couples, which has at the same time characteristics of a simple manufacture, easy and reversible assembling and disassembling in case of maintenance, and low cost and which allows to avoid fluid leakages in a simple, reliable and long- lasting manner.

The present invention therefore relates, in a first aspect thereof, to a connection assembly for reversibly connecting in a sealing manner a first female tubular element made of a first metallic material to a second male tubular element made of a second metallic material different from said first material, wherein the connection assembly comprises: a) at least one flange radially extending from a respective end portion of at least one of said first and second tubular element; b) a coupling element made of plastic of said first and second tubular element, said coupling element comprising a fork-shaped body configured so as to axially cooperate with the end portions of said first and of said second tubular element at said at least one flange so as to prevent a reciprocal axial sliding of the first and of the second tubular element; c) a bushing made of plastic comprising a substantially cylindrical body associated to a radially inner wall of the end portion of the first female tubular element, said substantially cylindrical body being configured so as to slidably receive with substantial shape coupling a free end portion of the second male tubular element; which is characterised in that the bushing is reversibly coupled in a sliding manner within the end portion of the first female tubular element and in that the connection assembly further comprises: d) at least a first radial sealing element associated to a radially outer wall of the substantially cylindrical body of the bushing and configured so as to cooperate in a sealing manner with a radially inner wall of said end portion of the first female tubular element; and e) at least a second radial sealing element arranged between an end portion of the second male tubular element and a radially inner wall of the substantially cylindrical body of the bushing. In the following description and in the subsequent claims, the terms "axial" and "axially", are used to indicate the longitudinal direction of the tubular elements, in other words, the direction extending along the flow direction of the fluid flowing inside the tubular elements. According to an aspect of the invention, the bushing made of plastic of the connection assembly is structurally independent from the male and female tubular elements reversibly connected to each other in a sealing manner thanks to the configuration of the connection assembly. Advantageously, the connection assembly of the invention prevents the onset of galvanic corrosion phenomena between the two tubular elements made of different materials, in an extremely simple way and at low cost essentially thanks to two elements made of plastic which may be manufactured by moulding on a large scale and at low cost, in other words the coupling element and the bushing. More specifically, in the connection configuration the bushing made of plastic is interposed between the two tubular elements acting as an insulation element and preventing any direct contact between the tubular elements, whereas the coupling element made of plastic connects the two tubular elements preventing any appreciable reciprocal sliding thereof along the axial direction without allowing any transport of electrical charges and, therefore, preventing the formation of a galvanic couple.

Advantageously, the connection assembly according to the invention allows to make a connection between the male and female tubular elements in a very simple, quick and precise manner, in particular without the need to prepare specifically and in a manner different from what is normally done, both the end portion of the female tubular element, and the end portion of the male tubular element limiting as much as possible or avoiding additional operations required on the latter.

In addition, the connection assembly according to the invention advantageously allows to make a connection between male tubular elements of the conventional type and generally used in the field of water-heating or air-conditioning apparatuses without any need to use expensive and dedicated multi-layer structures as foreseen for example by document JP 2010/151305.

Advantageously, the connection assembly according to the invention allows to accomplish a removable connection between the male and female tubular elements which allows an easy and quick disconnection of the tubular elements in the case of replacement of one of its elements or in the case of other requirements related, for example, to the disassembling of a heat exchanger from the hydraulic circuit of a water- heating or air-conditioning apparatus. In particular, the sliding connection which is accomplished between the free end portion of the second male tubular element and the bushing allows an easy removal of the male tubular element simplifying the maintenance operations. Advantageously, moreover, the connection assembly according to the invention may be easily and reversibly assembled and disassembled in case of maintenance since the bushing made of plastic interposed between the end portions of the female tubular element and of the male tubular element is slidably reversibly coupled in a sealing manner to said tubular elements thanks to the aforementioned at least a first and at least a second radial sealing element.

Thanks to the reversible and sliding coupling between the bushing and the tubular elements it is thus possible to carry out all the required maintenance interventions, such as for example disassembling a damaged bushing and assembling another one or replacing the aforementioned first and second radial sealing elements, in an extremely quick and simple manner.

Additional preferred features of the connection assembly according to the invention are defined in the attached claims 2-24, the content of which is herein integrally incorporated by reference. In a preferred embodiment, the aforementioned bushing comprises a flange outwardly radially extending from a free end of its substantially cylindrical body facing the second male tubular element in a connection configuration of the tubular elements.

In this way, it is advantageously possible to facilitate both the assembling and disassembling operations of the bushing in the end portion of the first female tubular element.

Preferably, the flange of the bushing abuts against the aforementioned at least one flange radially extending from a respective end portion of at least one of said first and second tubular element.

In this way, the flange radially extending from the first and/or from the second tubular element forms an abutment element by means of which it is advantageously possible to position in a constant and repeatable manner the bushing within the end portion of the first female tubular element in the assembling operations.

Preferably, the flange of the bushing abuts against a flange radially extending from a free end of the first female tubular element. In this way, it is advantageously possible to exploit a single abutment flange formed just in the first female tubular element and avoid the need to form a special abutment flange with additional processing in the male tubular element in all those cases, such as for example in the connection between a heat exchanger and a pipe of an external hydraulic circuit, where the male tubular element is not normally provided with an abutment flange configured to cooperate with a corresponding flange formed in the female tubular element (the joining element of the heat exchanger).

Preferably, the aforementioned at least a first and at least a second radial sealing element are made of a suitable material capable to ensure a fluid-tight seal. Preferred suitable materials are for example those of the elastomeric type, preferably vulcanized elastomeric materials, such as for example NBR, HNBR and EPDM rubbers, thermoplastic elastomers (TPE) such as for example vulcanized thermoplastic elastomers (TPV) and polyurethane thermoplastic elastomers (TPU). In a preferred embodiment, the bushing comprises a plurality, and still more preferably, a pair of first radial sealing elements axially spaced apart from one another and associated to the radially outer wall of the substantially cylindrical body of the bushing.

In this way, it is advantageously possible to ensure a fluid-tight seal which is particularly reliable in time even in the case of breaking or ageing of one of the two radial sealing elements.

Preferably, one of said first radial sealing elements is associated to the radially outer wall of the substantially cylindrical body of the bushing at a free end of said body that is arranged axially more inwardly with respect to the end portion of the first tubular element in the assembled configuration of the bushing. In this way, it is advantageously possible - in particular in the case of heat exchangers for water-heating apparatuses - to ensure a particularly reliable fluid-tight seal since at least a first radial sealing element is arranged in the part of bushing (the free end of its body axially internal with respect to the first tubular element) most exposed to the pressurised fluid that flows in the tubular elements and pushes against the bushing itself and that generally has a temperature above 40-50°C.

Preferably, one of said first radial sealing elements is associated to the radially outer wall of the substantially cylindrical body of the bushing at a free end of said body that is arranged axially more outwardly with respect to the end portion of the first tubular element in the assembled configuration of the bushing. Within the framework of the preferred embodiment in which the bushing is provided with a flange, one of said first radial sealing elements is preferably associated to the radially outer wall of the substantially cylindrical body of the bushing close to the flange of the bushing in the assembled configuration of the bushing. In this way, it is advantageously possible to ensure a particularly reliable fluid-tight seal since at least a first radial sealing element is arranged in the part of the bushing most exposed to the action of environmental agents present outside of the tubular elements and which may compromise the seal (dust, dirt, temperature variations, etc.). Preferably, the aforementioned at least a first radial sealing element is comoulded or overmoulded on the radially outer wall of the substantially cylindrical body of the bushing.

In the following description and in the subsequent claims, the terms "comoulded" and "overmoulded" are used to indicate elements obtained by means of comoulding and, respectively, overmoulding operations, preferably by injection, of plastic material.

In the following description and in the subsequent claims, the term "comoulding" indicates a moulding operation, preferably by injection, wherein the materials forming the body of the bushing and, respectively, of the aforementioned at least one radial sealing element, are simultaneously fed to a suitable forming mould so as to form a bushing provided with at least one sealing element by means of a single moulding operation.

In the following description and in the subsequent claims, the term "overmoulding" indicates a moulding operation, preferably by injection, wherein the body of the bushing is made first and then the material of the first radial sealing element is applied in sequence thereon, preferably in suitable cavities as illustrated hereinafter, so as to form the first radial sealing element.

In this case, the injection sequence of the materials can be reversed.

Preferably, the overmoulding of the material of the first radial sealing element can be carried out in the same injection overmoulding apparatus (in which case the operation is also called double injection moulding), or in two different apparatuses, one dedicated to the moulding operation of the substantially cylindrical body of the bushing and one dedicated to the overmoulding operation of the first radial sealing element on the body of the bushing.

In this way, it is advantageously possible to manufacture at low cost and on a large scale a bushing already provided with the first radial sealing element(s) by means of a moulding process having a high productivity and which also allows to obtain high- quality bushings in a repeatable manner.

Moreover and depending upon the type of plastic used to form the substantially cylindrical body of the bushing and the first radial sealing element, it is advantageously possible to manufacture a bushing in which the first radial sealing element has a more or less strong adhesion degree to the body of the bushing, thereby obtaining a first radial sealing element that can be associated to the body in a reversible or substantially irreversible manner.

Preferably, the substantially cylindrical body of the bushing is provided with a respective housing seat of the aforementioned at least a first radial sealing element.

Advantageously, such a seat allows to hold the aforementioned at least a first radial sealing element in a secure, reliable and precise manner on the body of the bushing. Preferably, the aforementioned housing seat of said at least a first radial sealing element is provided with an annular projection configured to cooperate with the aforementioned at least a first radial sealing element.

In this way, it is advantageously possible to hold the aforementioned at least a first radial sealing element in an even more secure, reliable and precise manner on the body of the bushing.

In a preferred embodiment, the bushing comprises a pair of first radial sealing elements axially spaced apart from one another and the aforementioned annular projection is formed in the housing seat of the radial sealing element arranged axially inwardly with respect to the end portion of the first female tubular element in the assembled configuration of the bushing.

In the preferred embodiment in which the bushing comprises a pair of first radial sealing elements axially spaced apart from one another, the radially outer wall of the substantially cylindrical body of the bushing preferably comprises a plurality of substantially axial grooves. Advantageously, these grooves allow the comoulding or overmoulding operations of the two first radial sealing elements.

Furthermore, in this way it is possible to obtain a coiTesponding plurality of seams of material housed in the grooves and which advantageously contribute to hold the first radial sealing elements in position and connected to each other. Preferably, the aforementioned at least a second radial sealing element arranged between the end portion of the second male tubular element and the radially inner wall of the substantially cylindrical body of the bushing is associated to a radially outer wall of the second male tubular element.

In a preferred embodiment of the invention, the end portion of the second male tubular element comprises at least one annular projection, said annular projection preferably having an outer diameter substantially equal to the inner diameter of the cylindrical body of the bushing.

Preferably, the aforementioned at least one annular projection is integrally fomied by bending by means of plastic deformation the end portion of the second male tubular element.

In this way, it is advantageously possible to have a particularly simple and cheap connection assembly for all those connections wherein the male tubular element is already provided per se with an annular projection, such as for example in the case of an external hydraulic circuit of a water-heating or air-conditioning apparatus.

In a particularly preferred embodiment, the aforementioned at least a second radial sealing element is removably received in a respective housing seat formed at an end portion of the second male tubular element.

In a preferred embodiment, such a housing seat of the aforementioned at least a second radial sealing element is made by means of conventional plastic deformation operations of the second male tubular element which are normally carried out on the ducts in the field of hydraulic circuitry for water-heating or air-conditioning apparatuses to form the annular projection described above.

The housing seat of the aforementioned at least a second radial sealing element is in particular preferably defined by forming a pair of annular projections suitably axially spaced apart from one another by means of the aforementioned conventional and usual plastic deformation operations of the male tubular element. In this case, therefore, the connection assembly of the invention is capable to exploit the conventional configuration of the end portion of the second tubular element, for example of the end portion of a pipe of a hydraulic circuit of a water-heating or air- conditioning apparatus, without the need of any additional processing on such a tubular element or of any application of additional elements to the male tubular element and/or to the female tubular element as required by the prior art cited above.

The connection assembly of the invention can thus be made in a simple and cost- effective manner by exploiting the conventional configuration of the end portion of the first and of the second tubular element and by using just two elements made of plastic which may be manufactured on a large scale and at low cost: the bushing reversibly internally associated in a sliding manner within the first tubular element (for example a tubular joining element of a heat exchanger) and the coupling element that is reversibly applied outside the two tubular elements at the aforementioned at least one flange. In a preferred embodiment, the free end portion of the second male tubular element is completely received within the bushing in the connection configuration between the male tubular element and the female tubular element accomplished by the connection assembly.

In this way and since the bushing is made of plastic, it is advantageously possible to avoid an accidental contact between the tubular elements made of different metallic materials, a contact which is on the other hand possible using the joining devices described in the aforementioned documents US 4,524,995 and JP 2008-240984, thereby preventing phenomena of galvanic corrosion.

Within the framework of this preferred embodiment, the bushing is preferably internally provided with a stop element configured to cooperate in abutment relationship with a free end of the second male tubular element.

In this way, it is advantageously possible to avoid an accidental contact between the tubular elements considerably simplifying the assembling operations of the connection assembly. Preferably, the aforementioned stop element comprises an annular shoulder which, in turn, is preferably internally formed within the bushing at an end portion of its substantially cylindrical body arranged axially inwardly with respect to the end portion of the first female tubular element in the assembled configuration of the bushing.

Preferably, such an annular shoulder cooperates in abutment relationship with an annular projection formed at the free end of the second male tubular element.

Preferably, the bushing is made of a plastic material suitable for the purpose. Preferred materials are thermoplastic polymers such as for example acetal resins.

In a preferred embodiment, the fork-shaped body of the coupling element comprises a pair of opposite shaped arms each provided with: - at least one substantially arc-shaped central portion configured to receive with substantial shape coupling the respective end portions of said first and of said second tubular element, and with - a central slot extending in the substantially arc-shaped central portion of each shaped arm and configured to receive said at least one flange radially extending from at least one of said first and second tubular element and, if present, from said flange of the bushing. Advantageously, the substantially arc-shaped central portion of the shaped arms of the coupling element couples to the respective end portions of the first and of the second tubular element applying a radially clamping pressing action thereon, whereas the central slot receives the flange of the first and/or of the second tubular element and, if present, the flange of the bushing, allowing the shaped arms to exert an abutment action adapted to prevent an axial sliding of the first and/or of the second tubular element.

Within the framework of this preferred embodiment, the substantially arc-shaped central portion of the aforementioned shaped arms is preferably shaped according to a curvature radius substantially equal to the radius of the first and/or of the second tubular element. Preferably, the central portion of each of said shaped arms comprises a pair of half- portions extending at axially opposite sides of said central slot, each of said half- portions being configured to: i) receive with substantial shape coupling a respective end portion of said first and of said second tubular element, respectively; and ii) radially cooperate with said respective end portion so as to grip the same; at least one of said half-portions being further provided with a slot-side edge configured so as to axially cooperate with said at least one flange radially extending from at least one of said first and second tubular element, said edge forming a stop element against the reciprocal axial sliding of said first and second tubular element. Advantageously, this configuration of the coupling element allows to effectively exert both a radial clamping action, preferably of the elastic or "spring" type, on the tubular elements, and an abutment action capable to prevent an axial sliding of the first and/or of the second tubular element, axial sliding which is substantially prevented or at most limited to the clearances present in the assembled condition of the connection assembly. Within the framework of this preferred embodiment, each half-portion of the substantially arc-shaped central portion of the aforementioned shaped arms is preferably shaped according to a curvature radius substantially equal to the radius of the first and, respectively, of the second tubular element. In a preferred embodiment of the invention, the end portion of the second male tubular element comprises at least one annular projection, said annular projection having an outer diameter substantially equal to the inner diameter of the cylindrical body of the bushing. Moreover, the substantially arc-shaped central portion of each of the shaped amis of the fork- shaped body of the coupling element comprises: a) a first half-portion provided with a slot-side edge configured so as to axially cooperate with a flange radially extending from the free end of said first female tubular element, and b) a second half-portion provided with a slot-side edge configured so as to axially cooperate with said annular projection of the second tubular element, said slot-side edges of the first and second half-portion of the shaped arms of the fork- shaped body forming said stop element against the reciprocal axial sliding of said first and second tubular element.

Preferably, the central slot extending in the central portion of each shaped arm has a width substantially equal to the axial thiclcness of said at least one flange radially extending from a respective end portion of at least one of said first and second tubular element or to the axial thickness of said at least one flange and of the flange of the bushing, if present.

In this way, it is advantageously possible to have a connection assembly which is particularly effective in the connection of the tubular elements even in the absence of onerous processing or additional elements on the second male tubular element, since any appreciable movement of reciprocal axial sliding, limited at most to the clearances present in the assembled condition of the connection assembly, is prevented even in the case in which pressurised fluids flow in the tubular elements. Preferably, the shaped arms of the fork-shaped body of the coupling element comprise a free end portion outwardly inclined with respect to the substantially arc-shaped central portion.

Advantageously, the outwardly inclined free end portions facilitate the assembling and disassembling operations of the coupling element. Preferably, the coupling element is made of a plastic material suitable for the purpose. Preferred suitable materials are thermoplastic polymers such as for example polyamide, optionally charged with a suitable reinforcing material, such as for example glass fibres. In a preferred embodiment, the aforementioned first female tubular element comprises a tubular joining element of a duct of a heat exchanger.

Preferably, the aforementioned at least one tubular joining element comprises a socket joint. Preferably, moreover, the aforementioned first metallic material is aluminium or alloys thereof.

In a preferred embodiment, the aforementioned second male tubular element comprises an end portion of a pipe of a hydraulic circuit of a water-heating apparatus or of an air- conditioning apparatus. Preferably, said second metallic material is copper or alloys thereof.

In a second aspect thereof, the invention relates to a heat exchanger comprising at least one heat exchange section and at least one pair of fluid inlet/outlet ducts from said section, at least one of said ducts being provided with a respective tubular joining element made of a first metallic material and configured so as to receive an end portion of a respective pipe of an external hydraulic circuit made of a second metallic material different from said first metallic material, which is characterised in that it comprises at least one bushing made of plastic comprising a substantially cylindrical body associated to a radially inner wall of an end portion of said tubular joining element of said at least one duct of the heat exchanger, said substantially cylindrical body being configured so as to receive in a sliding manner and with substantial shape coupling a free end portion of said pipe of the external hydraulic circuit, and in that said bushing is reversibly coupled in a sliding manner within the end portion of said tubular joining element and comprises at least a radial sealing element associated to a radially outer wall of the substantially cylindrical body of the bushing and configured so as to cooperate in a sealing manner with said radially inner wall of the end portion of the tubular joining element.

The heat exchanger according to the invention comprises the bushing foreseen in the connection assembly according to the invention described above, and such a bushing preferably has, individually or in combination, all the structural and functional features discussed above with reference to the connection assembly of the invention. Therefore, the heat exchanger of the invention also possesses all the advantages described hereinabove.

Preferred features of the heat exchanger according to the invention are defined in the attached claims 26-37, the content of which is herein integrally incorporated by reference.

In a third aspect thereof, the invention relates to a bushing made of plastic for use in a connection assembly configured so as to reversibly connect in a sealing manner a first female tubular element made of a first metallic material to a second male tubular element made of a second metallic material different from said first metallic material, said bushing comprising: a) a substantially cylindrical body configured so as to: i) cooperate in a sliding manner and with shape coupling with a radially inner wall of an end portion of said first female tubular element, and ii) receive in a sliding manner and with substantial shape coupling a free end portion of the second male tubular element, and b) at least a radial sealing element associated to a radially outer wall of said substantially cylindrical body and configured so as to cooperate in a sealing manner with a radially inner wall of said end portion of the first female tubular element.

The bushing according to the invention preferably has, individually or in combination, all the structural and functional features discussed above with reference to the connection assembly of the invention. Therefore, the bushing of the invention also possesses all the advantages described hereinabove. Preferred features of the bushing according to the invention are defined in the attached claims 39-47, the content of which is herein integrally incorporated by reference.

Brief description of the drawings

Additional features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment thereof, made with reference to the attached drawings and given as a non-limiting example.

The different features of the single configurations of the preferred embodiments described hereinbelow can be combined with one another as desired according to the preceding description, whenever it is desired to achieve the advantages specifically resulting from a particular combination. In the drawings: figure 1 a is a schematic perspective view of a heat exchanger according to the invention connected to a pipe of an external hydraulic circuit by means of a connection assembly according to a first preferred embodiment of the invention; figure lb is a schematic perspective view of the connection assembly of figure 1 (in particular, of the portion of figure 1 indicated with a dashed circle), in an enlarged scale with respect to figure 1 and in partial cross-section, wherein said connection assembly includes a bushing and a coupling element according to a second preferred embodiment of the invention; figure 2 is a schematic top plan view of the bushing of figure lb; - figure 3 is a schematic longitudinal cross-section view of the bushing of figure 2, taken along to the diametral plane indicated by line III - III of figure 2; figure 4 is a schematic cross-section view of the bushing of figure 3, taken along the plane indicated by line IV - IV of figure 3; figure 5 is a schematic perspective view of the coupling element of figure 1 a; - figure 6 is a schematic top plan view of the coupling element of figure 5; figure 7 is a schematic lateral view of the coupling element of figure 6, taken from a right-side point of view of figure 6; figure 8 is a schematic lateral view of the coupling element of figure 6, taken from a top point of view of figure 6. Detailed description of a currently preferred embodiment of the invention

With initial reference to figures la and lb, a heat exchanger 5 is shown connected to a pipe 12 of an external hydraulic circuit (not illustrated in full), for example the hydraulic circuit of a water-heating apparatus, not shown, by means of a connection assembly 1 according to the invention. In the preferred embodiment illustrated, the heat exchanger 5 is entirely made of aluminium.

In a way known per se, the heat exchanger 5 comprises a heat exchange section 7 and a pair of fluid inlet/outlet ducts from said section 7 (in figure la just the fluid outlet duct 9 is shown). In the preferred embodiment illustrated, the end portion of the fluid inlet/outlet ducts forms a tubular joining element integrally made of the same material as the ducts, in this case aluminium.

In figure la only the fluid outlet duct 9 with the corresponding tubular joining element 10 is visible.

Preferably and as is known in the art, the tubular joining element 10 comprises a socket joint integrally formed at a free end thereof.

The tubular joining element 10 is connected to the pipe 12, which is made of a second metallic material different from the first metallic material, for example copper that is the material usually used in water-heating apparatuses to make the pipes of the hydraulic circuit.

In the preferred embodiment illustrated, the tubular joining element 10 constitutes a first female tubular element in which a second male tubular element, consisting in this case of the pipe 12, is inserted in a fluid-tight sealing manner, in a reversible manner and with a substantial shape coupling, as will be described in greater detail hereinbelow.

The reversible fluid-tight sealing connection between the tubular joining element 10 and the pipe 12 is accomplished by means of a connection assembly 1 according to a preferred embodiment of the invention.

The connection assembly 1 includes a bushing 20, shown in greater detail in figures 2-4, and a coupling element 30, shown in greater detail in figures 5-8.

Both the bushing 20 and the coupling element 30 are structurally independent both from the first female tubular element (the tubular joining element 10), and from the second male tubular element (the pipe 12) as will be described in greater detail hereinbelow.

Moreover, the bushing 20 is reversibly coupled in a sliding manner within the end portion of the first female tubular element (the tubular joining element 10) as will become more readily apparent hereinbelow.

The bushing 20 and the coupling element 30 are made of plastic preferably by moulding; preferably, furthermore, the plastic material used is thermoplastic.

In a preferred embodiment, the bushing 20 is made of acetal resin and the coupling element 30 is made of polyamide charged with glass fibres.

The bushing 20 comprises a substantially cylindrical body 21 provided with a radially outer wall 21a and with a radially inner wall 21b. In a connection configuration of the tubular joining element 10 to the pipe 12 (figures la and lb), the radially outer wall 21a of the body 21 is associated in a fluid-tight sealing and reversible manner to a radially inner wall 10a of an end portion of the tubular joining element 10, and the radially inner wall 21b of the body 21 is associated in a fluid-tight sealing manner, again in a reversible manner, to a radially outer wall 12a of a free end portion of the pipe 12.

Preferably, the free end portion of the tubular joining element 10 comprises a flange 10b, extending substantially radially outwards, preferably perpendicularly to the axis of the tubular joining element 10 itself. Preferably, the bushing 20 comprises as well, at a free end thereof, a respective flange 20c extending substantially radially outwards, preferably perpendicularly to the axis of the bushing 20 itself.

Preferably, the flange 20c abuts against the flange 10b of the tubular joining element 10 in the assembled configuration of the bushing 20 (figure lb). Preferably, the bushing 20 comprises at least a radial sealing element, still more preferably a pair of radial sealing elements 22, 24 axially spaced apart from one another, associated to the radially outer wall 21a of the body 21 of the bushing 20 and configured to cooperate in a sealing manner with the radially inner wall 10a of the free end portion of the tubular joining element 10. In the preferred embodiment illustrated, the radial sealing element 24 is associated to the radially outer wall 21a of the body 21 of the bushing 20 at a free end of the body 21 that is arranged axially more inwardly with respect to the end portion of the tubular joining element 10 in the assembled configuration of the bushing itself.

In this way, it is advantageously possible to ensure a particularly reliable fluid-tight seal since the radial sealing element 24 is arranged in the part of the bushing 20 most exposed to the pressurised fluid that flows in the tubular joining element 10 towards the pipe 12.

Preferably, the radial sealing element 24 is arranged between a mouth portion 21d of the body 21 of the bushing 20 located at the opposite end of the flange 20c and the radially inner wall 10a of the free end portion of the tubular joining element 10.

Preferably, the radial sealing element 24 is an o-ring, preferably made of elastomeric material for example a vulcanized elastomeric material, such as for example HNBR rubber or thermoplastic elastomer (TPE) or another elastomeric material suitable for the puipose.

In the preferred embodiment illustrated, the radial sealing element 22 is associated to the radially outer wall 21a of the body 21 of the bushing 20 at a free end of said body that is arranged axially more outwardly with respect to the end portion of the tubular joining element 10 in the assembled configuration of the bushing itself.

In this way, in addition to obtaining a particularly reliable fluid-tight seal related to the presence of two radial sealing elements, it is also advantageously possible to achieve a protecting action from the environmental agents present outside of the tubular elements 10 and 12 and that can compromise the seal of the connection (dust, dirt, temperature variations, etc.).

Preferably, the radial sealing element 22 is interposed between the radially outer wall 21a of the bushing 20 and the radially inner wall 10a of the free end portion of the tubular joining element 10. In the non-limiting example of figures lb and 3, the radial sealing element 22 is preferably located near the flange 20c of the bushing 20. Preferably, the radial sealing element 22 is an o-ring, preferably made of elastomeric material for example thermoplastic elastomer (TPE) or another elastomeric material suitable for the purpose.

In the preferred embodiment illustrated, the body 21 of the bushing 20 is provided with respective housing seats of the radial sealing elements 22 and 24. Preferably, the housing seat of the radial sealing element 22 is constituted by an annular groove 25 formed in the radially outer wall 21a of the bushing 20 near the flange 20c (see figure 3).

Preferably, the housing seat of the radial sealing element 24 is, on the other hand, constituted by the mouth portion 21d of the body 21, which has a smaller diameter with respect to the radially outer wall 21 a of the bushing 20.

In the non-limiting example of figure lb, the mouth portion 21 d preferably comprises an annular projection 21e, configured to cooperate with the sealing element 24, which performs an advantageous and effective holding function of the radial sealing element 24. In a preferred embodiment, one or both the radial sealing elements 22, 24 can be overmoulded on the body 21 of the bushing 20 in the same moulding apparatus by means of overmoulding operations known in the art. In order to allow the comoulding or overmoulding operations of the radial sealing elements 22, 24 and of the bushing 20, the radially outer wall 21a of the latter preferably comprises a plurality of substantially axial grooves 2 If. In the non-limiting example of figure 4, the radially outer wall 21a of the bushing 20 preferably comprises two axial grooves 21f arranged in diametrically opposite positions.

In the finished bushing 20 and after the comoulding or overmoulding operations, respective seams formed by the elastomeric material used to form the radial sealing elements 22, 24 are received in the axial grooves 21f (see figure 3).

According to the invention, the fluid-tight seal between the bushing 20 and the free end portion of the pipe 12 is accomplished thanks to at least a radial sealing element, for example an o-ring 14, preferably made of elastomeric material (for example HNBR rubber) and arranged between the end portion of the pipe 12 and the radially inner wall 21b of the substantially cylindrical body 21 of the bushing 20.

Preferably, the o-ring 14 is associated to the radially outer wall 12a of the pipe 12. More preferably, the o-ring 14 is removably received in a respective housing seat 12d formed at an end portion of the pipe 12.

To this end, in the preferred embodiment illustrated the free end portion of the pipe 12 comprises two annular projections 12b and 12c, axially offset from one another and defining such a seat 12d. The o-ring 14 is thus arranged between the radially outer wall 12a of the pipe 12 and the radially inner wall 21b of the body 21 of the bushing 20 so as to exert an adequate fluid-tight seal.

In the non-limiting preferred embodiment of figure lb, the annular projection 12b is preferably provided at the free end of the pipe 12, and the annular projection 12c is flanked by an additional annular projection 12e. Preferably, the aforementioned annular projections 12b, 12c and 12e have an outer diameter substantially equal to the inner diameter of the substantially cylindrical body 21 of the bushing 20.

Preferably, furthermore, the aforementioned annular projections 12b, 12c and 12e are obtained by means of conventional plastic deformation operations of the free end portion of the pipe 12 which are entirely common for pipes forming part of a hydraulic circuit of a water-heating apparatus.

In this way, it is advantageously possible to position the o-ring 14 sufficiently far from the end located at the axially outer side of the bushing 20 in a connection configuration of the tubular joining element 10 to the pipe 12, thus ensuring an effective fluid-tight seal between the inner wall 21b of the body 21 of the bushing 20 and the free end portion of the pipe 12.

The annular projection 12e also constitutes - as will be better apparent in the following - an abutment element for the coupling element 30 configured to prevent a reciprocal axial sliding of the tubular joining element 10 and of the pipe 12.

In the preferred embodiment illustrated, the free end portion of the pipe 12 is completely received within the bushing 20.

To this end, the bushing 20 is preferably internally provided with a stop element 15 configured to cooperate in abutment relationship with the free end of the pipe 12 so as to avoid a possible accidental contact between the pipe 12 and the tubular joining element 10 during the assembling operations of the connection assembly 1.

In the preferred embodiment illustrated, the stop element 15 comprises an annular shoulder formed at an end portion of the body 21 of the bushing 20 and arranged axially more inwardly with respect to the end portion of the tubular joining element 10 (see figures lb and 3).

Preferably, the annular shoulder 15 is internally defined within the bushing 20 by the mouth portion 21d of the body 21, which has a smaller diameter with respect to the radially outer wall 21a of the bushing 20, and which cooperates in abutment relationship with the annular projection 12b formed at the free end of the pipe 12.

In the connection assembly 1 and as outlined above, the coupling element 30 (figures 5- 8) acts to radially grip in a pliers-like manner respective end portions of the tubular joining element 10 and of the pipe 12, defining and at the same time fixing in a reversible manner the joining configuration of the tubular joining element 10 to the pipe 12 with a substantial absence of reciprocal axial sliding.

To this end, the coupling element 30 comprises a fork-shaped body 30a configured to axially cooperate with the end portions of the tubular joining element 10 and of the pipe 12 at the flange 10b so as to prevent a reciprocal axial sliding of the tubular joining element 10 and of the pipe 12. Preferably, the fork-shaped body 30a of the coupling element 30 comprises a pair of opposite shaped arms 30b that, in the connected configuration of the tubular joining element 10 to the pipe 12, grip respective end portions of the tubular joining element 10 and of the pipe 12 (figures la and lb) so as to radially cooperate with said end portions so as to press against the same.

Preferably, each of the opposite shaped arms 30b comprise a first half-portion 30c, defining a housing seat of the free end portion of the tubular joining element 10 and a second half-portion 30d defining a housing seat of the free end portion of the pipe 12. Preferably, the first and second half-portion 30c, 30d have a substantially curvilinear profile. More preferably, the first and second half-portion 30c, 30d have respective curvature radii, different from each other, substantially equal to those of the free end portion of the tubular joining element 10 and of the pipe 12 (as shown in the non- limiting example of figure lb). In other words, in this preferred embodiment the first and the second half-portion 30c, 30d of each shaped arm 30b form together a substantially arc-shaped central portion of each shaped ann 30b, which central portion is configured to receive with substantial shape coupling the respective end portions of the tubular joining element 10 and of the pipe 12. Preferably, each shaped arm 30b comprises a central slot 30g extending in the substantially arc-shaped central portion thereof and configured to receive the flanges 10b of the tubular joining element 10 and 20c of the bushing 20. In this preferred configuration, therefore, the half-portions 30c, 30d of each shaped arm 30b extend at axially opposite sides of the central slot 30g. In the preferred embodiment illustrated, the half-portions 30c, 30d of each shaped arm 30b comprise respective slot-side edges 3 Of and 30e defining respective axial abutment surfaces intended to cooperate in abutment relationship against: i) the flange 10b of the tubular joining element 10, at a side opposite with respect to the flange 20c of the bushing 20 which is in turn abutting against the flange 10b (in the case of the slot-side edge 3 Of of the half-portion 30c), and ii) an annular projection of the free end portion of the pipe 12, in this case the annular projection 12e of figure lb (in the case of the slot- side edge 30e of the half-portion 30d).

The slot-side edges 3 Of and 30e are therefore configured so as to axially cooperate with the flange 10b of the tubular joining element 10 and with the annular projection 12e of the pipe 12 and form respective stop elements against the reciprocal axial sliding of the tubular joining element 10 and of the pipe 12, which axial sliding is substantially prevented or limited at most to the clearances present in the assembled condition of the connection assembly 1 and related to the distance of the slot-side edge 30e from the annular projection 12e of the pipe 12.

In the non-limiting preferred example of figure lb, the axial distance between the slot- side edges 3 Of and 30e of the half-portions 30c, 30d which defines the axial extension of the central slot 30g in each of the arms 30b, is substantially equal to the sum of the axial thicknesses of the flange 10b of the tubular joining element 10 and of the flange 20c of the bushing 20.

In the preferred non-limiting example of figure lb, the annular projection 12e of the pipe 12 (where the slot-side edge 30e of the half-portion 30d is abutting) is located - in the connected configuration of the tubular joining element 10 to the pipe 12 - axially within the flange 20c of the bushing 20, substantially at the flange 20c itself, so that the slot-side edge 30e is arranged substantially flush with a transversal free end surface of the flange 20c.

Preferably, the fork-shaped body 30a further comprises a hinge element configured to facilitate the opening of the two arms 30b away from one another in the connection/disconnection operations of the coupling element 30.

In a first preferred embodiment, illustrated in figures 1 and 5-8, such a hinge element is constituted by a substantially C-shaped concave joining portion 3 Oh forming a sort of axial recess configured to connect the two arms 30b with each other. Preferably, the concave joining portion 3 Oh is arranged at the midpoint of the fork- shaped body 30a and has a substantially curvilinear profile, with a centre of curvature at an opposite side with respect to the arms 30b.

In a second preferred embodiment, illustrated in figure lb, such a hinge element is constituted by a convex joining portion 30m again substantially C-shaped and configured to connected the two arms 30b with each other.

Preferably, the convex joining portion 30m is arranged at the midpoint of the fork- shaped body 30a and has a substantially curvilinear profile, with centre of curvature at a same side as the arms 30b.

Preferably, the arms 30b also comprise a respective free end portion 30i which is outwardly inclined with respect to the substantially arc-shaped central portion, so as to facilitate the assembling/disassembling operations of the coupling element 30.

The assembling and working operations of the connection assembly 1 described above are as follows.

Firstly, it is necessary to mount the bushing 20 in the free end portion of the first female tubular element, in this case constituted by the tubular joining element 10 of the heat exchanger 5. As illustrated above, the bushing 20 is reversibly coupled in a sliding manner within the end portion of the female tubular element (the tubular joining element 10 of the heat exchanger 5).

The assembling of the bushing 20 is earned out by inserting the same in the tubular joining element 10 until the flange 20c of the bushing 20 abuts against the flange 10b of the tubular joining element 10 as illustrated in figure lb. Preferably, the bushing 20 is inserted within the tubular joining element 10 in a final production step of the heat exchanger 5 which is therefore advantageously supplied to the manufacturer of the water-heating or air-conditioning apparatus ready for connection with the hydraulic circuit of the apparatus.

Alternatively, the insertion of the bushing 20 within the free end portion of the first female tubular element, for example of the tubular joining element 10 of the heat exchanger 5, can be carried out when connecting together the female tubular element and the male tubular element in this preferred embodiment consisting of the pipe 12 of the hydraulic circuit of a water-heating or air-conditioning apparatus.

The radial sealing elements 22 and 24 ensure an effective fluid-tight seal at the interface between the bushing 20 and the tubular joining element 10, so as to stop fluid leakages (for example water in the case of a water-heating apparatus) during operation.

Although only one radial sealing element may be sufficient to ensure an adequate fluid- tight seal, the preferred embodiment illustrated provides for the use of the two radial sealing elements 22 and 24 so as to ensure such a seal even in the most demanding operating conditions.

The o-ring 14, on the other hand, is mounted in its housing seat 12d at the free end portion of the male tubular element (the pipe 12 of the external hydraulic circuit).

The free end portion of the male tubular element (the pipe 12) is thus reversibly connected in a sliding manner to the female tubular element (the tubular joining element 10 of the heat exchanger 5), by inserting the same in the bushing 20. In the embodiment illustrated, the free end portion of the male tubular element (the pipe 12) is preferably inserted until the additional annular projection 12e is located substantially flush with the flange 20c of the bushing 20. Advantageously, the bushing 20 of the connection assembly 1 is configured to prevent an undesired excessive axial insertion of the pipe 12 within the tubular joining element 10 thanks to the presence of the annular shoulder 15 which is configured to cooperate in abutment relationship with the projection 12b of the pipe 12. In this way, it is possible to ensure that the pipe 12 is completely received within the bushing 20 in the connection configuration of the pipe 12 with the tubular joining element 10 avoiding undesired accidental contacts between different metallic materials.

At this point, the assembling of the connection assembly 1 is completed by mounting the coupling element 30 configured so as to maintain the female tubular element (the tubular joining element 10) and the male tubular element (the pipe 12) in the correct connection position.

In particular, the opposite shaped arms 30b of the coupling element 30 grab the end portions of the female tubular element (the tubular joining element 10) and, respectively, of the male tubular element (the pipe 12), by elastically pressing along the radial direction with the respective first and second half-portion 30c and 30d.

Moreover, the slot-side edges 30e and 30f of the opposite shaped arms 30b abut against the annular projection 12e formed at the free end portion of the male tubular element (the pipe 12) and, respectively, against the flange 10b of the female tubular element (the tubular joining element 10). In the preferred embodiment according to which the heat exchanger 5 is a gas-water exchanger of a water-heating apparatus (for example a water heater or a boiler), the pressure of the fluid (water or other suitable heat earner liquid) circulating in the exchanger itself and in the hydraulic circuit of the apparatus tends to push the pipe 12 away from the tubular duct 10 along an axial direction and automatically positions the annular projection 12e in abutment against the slot-side edge 30e of the second half- portion 30d of the shaped arms 30b of the coupling element 30 during use.

When it is desired to disconnect the tubular joining element 10 from the pipe 12, for example for a maintenance intervention, it is sufficient to remove the coupling element 30 by pulling it out along the radial direction from the female and male tubular elements (the tubular joining element 10 and the pipe 12) and then by pulling out the male tubular element (the pipe 12) from the female tubular element (the tubular joining element 10).

Advantageously, the removal of the coupling element 30 is carried out extremely quickly and easily, by a mere manual operation. In fact, it is sufficient to manually pull apart the opposite arms 30b, so as to disengage the first and the second half-portion 30c and 30d from the free end portions of the female tubular element (the tubular joining element 10) and of the male tubular element (the pipe 12) until the coupling element 30 is removed by laterally moving the same along a radial direction. Advantageously, the opening of the fork-shaped body 30a, i.e. the movement of the two amis 30b away from each other, and the subsequent elastic return of the two arms 30b into the rest position (so as to allow a subsequent use of the same coupling element 30 for a subsequent connection between the male and female tubular elements), is facilitated by the hinge element constituted by the convex joining portion 30m (non- limiting example of figure lb) or by the concave joining portion 3 Oh (non-limiting example of figures 1 and 5-8).

In this way, it is advantageously possible to insert or remove the fork-shaped body 30a astride of the free end portions of the female tubular element (the tubular joining element 10) and of the male tubular element (the pipe 12) minimising the risk of breaks or damage even after repeated insertion/removal operations.

Once the pipe 12 has been disconnected from the tubular joining element 10, an operation that can be earned out very easily thanks to the sliding connection between the pipe 12 and the bushing 20, it is possible to remove in an equally easy manner the bushing 20 from the tubular joining element 10 if the bushing 20 and/or one or both of the radial sealing elements 22, 24 are damaged and should be replaced.

Clearly, in order to satisfy specific and contingent requirements, a person skilled in the art can bring numerous modifications and variants to the connection assembly, to the heat exchanger and to the bushing described above, all of which are in any case encompassed by the scope of protection of the present invention as defined by the following claims.