Sealed connection for a connector to a coaxial tubular heat exchanger

Abstract

A method for sealing a connector (12) to a coaxial tubular heat exchanger (14), particularly for a motor vehicle air conditioning circuit, characterized in that it comprises the following successive steps: a) a free end (14b1) of an external tube of the exchanger is mounted in or on the connector (12), b) the external tube (14b) is secured directly to the connector, c) an internal tube (14a) is inserted into the external tube (14b) until a free end (14a1) of the internal tube is mounted in or on the connector (12), this assembly ensuring a seal between the internal tube and the connector, and d) the internal (14a) and external (14b) tubes are secured directly to each other to prevent relative movement.

Description

[0001] The present invention relates in particular to a method for the sealed connection of a connector to a coaxial tubular heat exchanger, as well as a fluid connection device, in particular for a vehicle air conditioning circuit. Technical background

[0002] The technical background includes in particular documents WO-A1-2011 / 057594, WO-A1-2019 / 05058, EP-A1-0 276 521, EP-A1-2 199 721, GB-A-2 0285 574, US-A1-2009 / 260586 and WO-A1-2007 / 013439.

[0003] In some air conditioning circuits for motor vehicles, particularly those using carbon dioxide or R134a as refrigerant, it is necessary to carry out a heat exchange or transfer between the fluid in the high-pressure portion of the circuit that is to be cooled and the same fluid from the low-pressure portion of this circuit, which serves as a cold source and is heated in exchange, to improve the efficiency of the circuit. For this purpose, a so-called "internal" heat exchanger is used, since it does not seek an exchange with the air outside the vehicle or with the air in the passenger compartment.

[0004] In general, a heat exchanger is metallic and is connected to the corresponding pipes of the air conditioning circuit which include in particular flexible hoses, via connectors mounted at each end of the exchanger, which may for example be of the plate type, consisting of a stack of flat tubes and carrying out the heat exchange both by convection with the air outside the exchanger and by conduction, or of the multi-tube type which in its simplest version is of the coaxial counter-current tubular type, then carrying out the heat exchange without the aforementioned convection.

[0005] In the latter case, this coaxial exchanger generally defines at least one radially internal channel delimited by a sleeve and intended to convey the fluid from the high pressure portion of the circuit, and at least one radially external channel between the sleeve and the casing of the exchanger and intended to convey the fluid from the low pressure portion of the circuit. The sleeve and the casing are formed from a single piece and connected together by longitudinal fins distributed around the circumference of the exchanger.

[0006] It is known to use two female connectors for the relevant end of such a coaxial exchanger, which are welded or brazed axially separately to both the sleeve and the casing via three welding or brazing lines, so that these connectors respectively define passage conduits for the fluid communicating in a sealed manner with these internal and external channels. For example, document WO-A1-2007 / 1013439 can be cited for the description of these connectors.

[0007] A major drawback of these internal coaxial exchangers equipped with female connectors lies in the mutual proximity of the generated welding or brazing lines which, in particular for successive brazing operations, generate risks of reflow of the previous brazing, and also in the need to carry out these welds or brazing blindly with risks of non-sealing at the junction and / or penetration of the brazing into the corresponding internal or external channel which can therefore lead to pressure losses, pollution or even blockage of these channels.

[0008] It is also known to use a single connector at the connection end of a coaxial exchanger, as for example described in document EP-A1-1 762 806 where the connector is assembled to the external casing and to the internal sleeve by brazing via an intermediate connection, and in document EP-A1-1 128 120 (figures 10 and following) where the connector is brazed directly onto the casing and onto the sleeve of the exchanger via two brazing beads.

[0009] A major drawback of the coaxial internal exchangers presented in these last two documents is that their assembly to a connector requires at least two brazing operations to be carried out at the same time and at least one of which, relating to the junction to be made between the connector and the internal sleeve, is necessarily "blind" or in difficult conditions due to its location inside the connector. This results in significant risks of non-conformity of the connection and therefore leakage of the transferred fluid. In addition, these brazing operations involve a relatively high manufacturing cost and a relatively high scrap rate for the connection obtained.

[0010] The Applicant has proposed a solution in document EP-A1-2 199 721. This solution consists of assembling the connector to the casing by welding, and to the sleeve by at least one annular sealing gasket which is mounted on an axial extension of the sleeve relative to the casing. The axial distance between the gasket and the weld line is sufficiently large so that this gasket is not altered by welding. The exchanger being formed from a single piece, the sleeve and the casing are inseparable and are therefore mounted simultaneously in the connector.

[0011] Although this solution is effective, it is not entirely satisfactory because the axial extension of the sleeve results in significant bulk for the exchanger and the connector.

[0012] An aim of the present invention is to propose an alternative to this solution. Summary of the invention

[0013] The present invention provides a method for the sealed connection of a connector to a coaxial tubular type heat exchanger, in particular for a motor vehicle air conditioning circuit, this exchanger comprising two coaxial tubes, respectively internal and external, the external tube defining around the internal tube a first annular channel for circulation of a first fluid, and the internal tube defining a second internal channel for circulation of a second fluid, the tubes being independent and one of the tubes comprising projections resting on the other of the tubes to keep them at a distance from each other, the connector comprising a block of material comprising two cavities for the passage of fluids communicating respectively with the channels of the exchanger, characterized in that it comprises the following successive steps: a) a free end of the external tube is mounted in or on the connector, b) the external tube is secured directly to the connector, c) the internal tube is inserted into the external tube until a free end of the internal tube is mounted blindly in the connector,this assembly without welding ensuring a seal between the internal tube and the connector, and d) the internal and external tubes are secured directly to each other, by plastic deformation of at least one of the tubes, to avoid relative movements.

[0014] Contrary to the teaching of document EP-A1-2 199 721, the internal and external tubes of the exchanger are independent. They are thus mounted one after the other in or on the connector. In particular, the external tube is mounted in step a) and secured to the connector in step b). This securing can be achieved by welding or brazing if the external tube and the connector are metallic. Alternatively, in the case where the external tube and the connector are made of other materials, their securing could be ensured by gluing, by electron beam welding, etc. During this securing step b), the internal tube is not yet inserted into the external tube and therefore does not risk being altered by the securing operation, and for example by the heating induced by securing by welding. The internal tube is then inserted in step c) into the external tube, until the internal tube cooperates in a sealed manner with the connector.This is a blind assembly. There is no actual connection of the inner tube directly to the connector. They are simply engaged one inside the other or one on top of the other. The inner tube is connected indirectly to the connector, via the outer tube. This connection of the tubes is carried out in step d) and prevents any relative movement between the tubes during operation.

[0015] The method according to the invention may comprise one or more of the following steps or characteristics, taken in isolation from one another or in combination with one another: step d) is carried out by crimping the outer tube onto the inner tube, or by simultaneously bending the inner and outer tubes; the method comprises, between steps b) and c), a step of mounting at least one annular sealing gasket around the free end of the inner tube; during steps a) and c), the tubes are engaged by male-female interlocking respectively in two housings of the connector; during steps a) and c), the tubes are guided at the entrance to the housings by cooperation of their free ends with chamfers of the connector; before step c), the free end of the inner tube is plastically deformed or comprises a plastically deformed member, to produce at least one annular groove at its outer periphery, and preferably two annular grooves adjacent to its outer periphery;before step c), the free end of the inner tube is plastically deformed or comprises a plastically deformed member, to modify its external diameter, at at least one end; the inner and outer tubes are made of metallic materials. the inner and outer tubes are made of different materials; the inner tube is metallic and the outer tube is made of plastic or composite material; the connection of the outer tube to the connector is carried out by welding, brazing or gluing; the connector is metallic. ;

[0016] The present invention also relates to a fluid connection device comprising a connector and a coaxial tubular type heat exchanger, in particular for a motor vehicle air conditioning circuit, the connector comprising a block of material forming two fluid passage cavities communicating respectively with channels of the exchanger, the exchanger comprising two coaxial tubes, respectively internal and external, the external tube defining around the internal tube a first annular channel for circulation of a first fluid, and the internal tube defining a second internal channel for circulation of a second fluid, the tubes being independent and one of the tubes comprising projections bearing on the other of the tubes to keep them at a distance from each other, characterized in that it is obtained by a method as described above and in that: the external tube comprises a free end which is engaged in or on the connector, this external tube being secured directly to the connector, and the internal tube comprises a free end which is mounted blindly in the connector, this assembly without welding ensuring a seal between the internal tube and the connector,the internal and external tubes being directly secured to each other, by plastic deformation of at least one of the tubes, to avoid relative movements.

[0017] Advantageously, the joining of the internal and external tubes is achieved by crimping the external tube onto the internal tube, by simultaneously bending the internal and external tubes, or by welding the ends of the internal and external tubes opposite the connector. Brief description of the figures

[0018] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: [ Fig. 1 ] there Figure 1is a schematic perspective view of a fluid connection device according to the invention, comprising in particular a heat exchanger and a connector, this device being in a first position preceding a shaping operation, [ Fig. 2 ] there Figure 2 is a schematic perspective view of the device of the Figure 1 , this device being in a second position following a shaping operation, [ Fig. 3 ] there Figure 3 is a schematic perspective view of a coaxial tubular heat exchanger, [ Fig. 4 ] there Figure 4 is a larger-scale schematic view of a detail of the device of the Figures 1 and 2 , the connector and part of the exchanger being shown in axial section, [ Fig. 5 ] there Figure 5 is a schematic axial sectional view of the connector of the device of the figures 1 to 3 , [ Fig. 6 ] there Figure 6is a schematic axial sectional view of a free end of an internal tube of the exchanger of the device of the figures 1 to 3 , [ Fig. 7 ] there Figure 7 is a flowchart showing steps of a method according to the invention for the sealed connection of a connector to an exchanger, and [ Fig. 8 ] there figure 8 is a partial schematic perspective view of an alternative embodiment of the device according to the invention. Detailed description of the invention

[0019] THE figures 1 to 6 illustrate an embodiment of a fluid connection device 10 according to the invention, for an air conditioning circuit of a vehicle, in particular an automobile.

[0020] Device 10 visible in its entirety at Figures 1 and 2 comprises in the example shown a connector 12, here female, and a heat exchanger 14 of coaxial tubular type.

[0021] The exchanger 14 has a generally elongated shape and comprises two coaxial tubes extending one inside the other. The inner tube is referenced 14a and the outer tube is referenced 14b.

[0022] The outer tube 14b defines around the inner tube 14a an annular channel C1 for circulation of a first fluid, and the inner tube 14a defines a second internal channel C2 for circulation of a second fluid ( Figure 3 ). To ensure sufficient spacing between the tubes and the formation of the channel C1, one of the tubes generally has projections, such as fins, resting on the other of the tubes to keep them at a distance from each other. The fins may extend parallel to the longitudinal axis X of the exchanger 14 or in a helical manner around this axis. They may be continuous or discontinuous.

[0023] It is thus understood that the external tube 14b can comprise on its internal cylindrical surface surrounding the internal tube 14a internal fins 15 which bear on an external cylindrical surface of the internal tube 14a ( Figure 3 ). Alternatively, the inner tube 14a may comprise on its external cylindrical surface surrounded by the outer tube 14b external fins which bear on an internal cylindrical surface of the outer tube 14b.

[0024] The tubes 14a, 14b may be made of the same or different materials. They may be made of metal alloy(s) or plastic material(s) for example.

[0025] The connector 12 is located at a longitudinal end of the exchanger 14, the opposite longitudinal end of which is connected to another type of connector 16, which is not part of the invention.

[0026] In the Figure 1 , interchange 14 has a straight shape. In the Figure 2, the exchanger 14 has a shape presenting several bends. The exchanger 14 of the Figure 2 has undergone a forming or shaping or bending step, from the initial shape of the Figure 1 . As will be explained in the following, this shaping can make it possible to secure the tubes 14a, 14b together, in particular in the areas where the tubes are bent simultaneously and plastically deformed by being clamped against each other. The device 10 of the Figure 2 is ready to be installed in an air conditioning circuit and used. Figure 4 is a larger scale view of the connector 12 and its connection to one end of the exchanger 14. The connector 12 is shown alone in the Figure 5 .

[0027] As can be seen in the Figure 4, the external tube 14b has a straight cut end (in a plane perpendicular to the longitudinal axis X of the exchanger 14) forming a free end 14b1, this free end 14b1 being engaged in a housing 18 of the connector 12.

[0028] The inner tube 14a has a free end 14a1 which is preferably formed integrally with the rest of the tube but which may alternatively be formed by attaching and securing a tubular member 20 to one end 14a2 of the tube 14a.

[0029] This free end 14a1 or this organ 20 is represented alone in the Figure 6The end 14a or the member 20 has undergone a forming or shaping operation. Before this operation, it / she comprises internal and external cylindrical surfaces and constant internal and external diameters. After this operation and as illustrated, it / she has a flared portion 20a for connection to the rest of the internal tube 14a. In the case of the use of an added member 20, the edge-to-edge connection of the member 20 to the end 14b1 of the tube 14a, as illustrated in Figure 4 , can be produced by welding or brazing for example. This portion 20a has internal diameters D1 and external diameters D2 substantially identical to those of the internal tube 14a.

[0030] The remainder of the end 14a1 or of the member 20 has an external cylindrical surface 20c whose external diameter D3 is less than D2, and here greater than D1. At its end 20b opposite the portion 20a, the end 14a1 or the member 20 comprises at least one external annular groove 22 for receiving an annular sealing joint 24.

[0031] In the example shown, the end 14a1 or the member 20 comprises two adjacent grooves 22 and therefore carries two seals 24 ( Figure 4 ).

[0032] The seals 24 are preferably made of elastomer. Alternatively, they could be made of metal.

[0033] The end 14a1 or the member 20 is intended to be engaged in a housing 26 of the connector 12 and the seals 24 are intended to cooperate with a surface, here cylindrical, of this housing 26.

[0034] We now refer to the Figure 5 which illustrates connector 12.

[0035] The connector 12 is in the form of a block of material, for example metal or plastic.

[0036] The connector 12 has a generally parallelepiped shape and comprises an upper face 12a, a lower face 12b, and side faces 12c.

[0037] The connector 12 comprises three ports 28, 30 and 32. The port 28 is located on one of the faces 12c and opens into a bore 34 comprising the housings 18 and 26.

[0038] The ports 30, 32 are substantially parallel to each other and perpendicular to the port 28 and to the axis of the bore 34 which is intended to be merged with the axis X of the exchanger 14.

[0039] The ports 30 and 32 are located on the upper face 12a and are spaced apart from each other. They form, for example, female elements configured to cooperate with male elements of a pipe or a fitting for the purpose of fluid communication between this pipe or fitting and the connector 12. The port 30 is located on the side of the port 28 and opens into a cavity 36 of the bore 34, and the port 32 is located on the side opposite the port 28 and opens into another cavity 38 of the bore 34.

[0040] Furthermore, between the ports 30, 32, the face 12a of the connector 12 comprises a threaded orifice 40 for receiving a screw for fixing the connector 12 to an element or to another fluid connector of the vehicle.

[0041] In the example shown, the bore 34 is stepped and therefore comprises several successive stages of different diameters and formed in particular by the housings 18, 26 and the cavities 36, 38.

[0042] The bore 24 first comprises the housing 18 which is connected to the port 28 and to the face 12c by a first chamfer 42. This housing 18 has an external diameter D4.

[0043] The bore 24 then comprises the cavity 36 which extends between the housing 18 and a chamfer 44 connecting to the other housing 26. The cavity 36 has an external diameter D5 and the housing 26 has an external diameter D6, D5 being between D4 and D6.

[0044] The housing 18 is connected to the cavity 36 by a cylindrical bearing surface 46. The bore 34 finally comprises the cavity 38 which is connected to the housing 26 by another cylindrical bearing surface 48 and which ends in a blind hole 50 in the vicinity of the face 12c opposite the port 28.

[0045] Cavity 38 has an external diameter D7, less than D6.

[0046] D4 is substantially identical to or slightly greater than the external diameter Dext of the free end 14b1 of the external tube 14b ( Figure 4 ).

[0047] D6 is substantially identical to or slightly greater than the external diameter D3 of the end 20b of the member 20 or of the free end 14a1 of the internal tube 14a.

[0048] The connection of the exchanger 12 to the connector 14 will now be described with reference to the Figure 7 which illustrates steps in a connection process.

[0049] The method comprises a first step a) in which the free end 14b1 of the external tube 14b is engaged in the housing 18 of the connector 12. The insertion of the end 14b1 into the port 28 is facilitated by the chamfer 42, and continued until it stops on the bearing surface 46. The external tube 14b forms a male part engaged in the housing 18 forming a female part. The reverse is however possible, the free end 14b1 then forming a female part engaged on a male portion of the connector 12. This engagement can be carried out manually by an operator.

[0050] The method comprises a following step b) of directly securing the external tube 14b to the connector 12. In the case where these two elements are made of a metal alloy, this securing can be carried out by welding, for example of the TIG type, an annular weld bead 52 then being formed at the level of the port 28 and the chamfer 42, around the external tube 14b ( Figure 4 ). In the case where the joining is carried out by brazing, the brazing could be almost invisible to the naked eye and for example essentially located inside the housing 18.

[0051] In the case where the tube 14b and the connector 12 are made of plastic or composite material, their joining could be ensured by gluing, electron beam welding, etc.

[0052] At the end of step b), the external tube 14b is fixed to the connector 12 and the internal tube 14a is not yet present in the device 10. The channel C1 is then in fluid communication with the port 30 via the cavity 36.

[0053] The inner tube 14a is mounted in the next step c). The inner tube 14a is inserted into the outer tube 14b until the free end 14a1 of the inner tube engages in the housing 26 of the connector 12.

[0054] The insertion of the end 14a1 into the housing 26 is facilitated by the chamfer 44 and continued until it stops on the bearing surface 48. The internal tube 14a also forms a male part engaged in the housing 26 forming a female part. The reverse is however conceivable, the free end 14a1 then forming a female part engaged on a male portion of the connector 12. This engagement can be carried out manually by an operator. It is understood that, insofar as the tubes are relatively rigid, these tubes are preferably straight to facilitate step c).

[0055] The mounting of the inner tube 14a in the connector 12 is such that it alone ensures a seal between the inner tube and the connector. It is therefore not necessary to provide a direct connection between these elements.

[0056] This sealing can be ensured by a simple cooperation of shapes or a simple support of complementary cylindrical surfaces between the internal tube 14a and the connector 12.

[0057] In the example shown in the drawings, the sealing is ensured by seals 24, the number and material of which can be adapted, as mentioned above.

[0058] Channel C2 is then in fluid communication with port 32 via cavity 38.

[0059] In the case shown and as mentioned above, the method comprises two additional optional steps, between steps b) and c), which consist on the one hand in shaping the free end 14a1 of the internal tube 14a, or a member 20 which is then attached to the end of the tube, then in mounting the seals 24 in the grooves 22 of this free end 14a1.

[0060] The method finally comprises a step d) in which the tubes 14a, 14b are secured together to avoid relative movements between them.

[0061] This joining can be achieved by shaping the exchanger 14, and in particular bending it, as mentioned above in relation to the Figure 2 The tubes 14a, 14b are then plastically deformed and held tightly against each other, thus preventing any relative movement between them.

[0062] The joining can be achieved by plastic deformation of only one of the tubes, and for example the external tube 14b which is crimped onto the internal tube 14a in a specific location E (cf. figure 8 ). In the example shown, the crimping results in depressions 54 and localized plastic deformations of the external tube 14b to bear on the internal tube 14a.

[0063] This joining can also be carried out by welding together the ends of the tubes 14a, 14b, opposite the connector 12 and therefore located on the side of the other connector 16.

[0064] The invention makes it possible to produce a sealed fluid connection between the exchanger 14 and the connector 12, without blind welding while limiting the size of the device 10.

Claims

1. Method for a sealed connection of a connector (12) to a heat exchanger (14) of the coaxial tubular type, in particular for a motor vehicle air-conditioning circuit, this exchanger comprising two coaxial tubes, respectively internal (14a) and external (14b), the external tube defining around the internal tube, a first annular channel (C1) for the circulation of a first fluid, and the internal tube defining a second internal channel (C2) for the circulation of a second fluid, the tubes being independent from one another and one of the tubes comprising projections (15) in abutment on the other of the tubes to keep the tubes at a distance from one another, the connector comprising a material block comprising two cavities (36, 38) for the passage of the fluids communicating respectively with the channels (C1, C2) of the exchanger, characterised in that it comprises the following successive steps: a) a free end (14b1) of the external tube is mounted in or on the connector (12), b) the external tube (14b) is directly secured to the connector, c) the internal tube (14a) is inserted in the external tube (14b) until a free end (14a1) of the internal tube is mounted in a blind manner in the connector (12), this mounting without welding ensuring a sealing between the internal tube and the connector, and d) the internal (14a) and external (14b) tubes are directly secured against one another, by plastic deformation of at least one of the tubes (14a, 14b), to avoid relative displacements.

2. Method according to claim 1, wherein step d) is carried out by crimping of the external tube on the internal tube, or by simultaneous bending of the internal and external tubes.

3. Method according to claim 1 or 2, wherein it comprises, between steps b) and c), a step of mounting at least one annular seal (24) around the free end (14a1) of the internal tube (14a).

4. Method according to one of the preceding claims, wherein, during steps a) and c), the tubes (14a, 14b) are engaged by male-female interlocking, respectively in two housings (18, 26) of the connector.

5. Method according to claim 4, wherein, during steps a) and c), the tubes (14a, 14b) are guided at the inlet of the housings (18, 26) by engagement of their free ends (14a1, 14b1) with chamfers (42, 44) of the connector (12).

6. Method according to one of the preceding claims, wherein, before step c), the free end (14a1) of the internal tube (14) is plastically deformed or comprises a plastically deformed member (20), to achieve at least one annular recess (22) at its external periphery, and preferably two annular recesses (22) adjacent to its external periphery.

7. Method according to one of the preceding claims, wherein, before step c), the free end (14a1) of the internal tube (14) is plastically deformed or comprises a plastically deformed member (20), to modify its external diameter (D2, D3), at at least one end.

8. Method according to one of the preceding claims, wherein the internal (14a) and external (14b) tubes are made of metallic materials.

9. Method according to one of claims 1 to 7, wherein the internal (14a) and external (14b) tubes are made of different materials.

10. Method according to the preceding claim, wherein the internal tube (14a) is metallic and the external tube (14b) is made of plastic or composite material.

11. Method according to one of the preceding claims, wherein the securing of the external tube (14b) to the connector (12) is achieved by welding, brazing or gluing.

12. Method according to one of the preceding claims, wherein the connector (12) is metallic.

13. Fluidic connection device (10) comprising a connector (12) and a heat exchanger (14) of the coaxial tubular type, in particular for a motor vehicle air-conditioning circuit, the connector comprising a material block forming two cavities (18, 26) for the passage of fluids communicating respectively with channels (C1, C2) of the exchanger, the exchanger comprising two coaxial tubes, respectively internal (14a) and external (14b), the external tube defining around the internal tube, a first annular channel (C1) for the circulation of a first fluid, and the internal tube defining a second internal channel (C2) for the circulation of a second fluid, the tubes being independent and one of the tubes comprising projections (15) in abutment on the other of the tubes to keep the tubes at a distance from one another, characterised in that it is obtained by a method according to one of the preceding claims, and in that: the external tube (14b) comprises a free end (14b1) which is engaged in or on the connector (12), this external tube being directly secured with the connector, and the internal tube (14a) comprises a free end (14a1) which is mounted in a blind manner in the connector, this mounting without welding ensuring a sealing between the internal tube and the connector, the internal (14a) and external (14b) tubes being directly secured against one another, by plastic deformation of at least one of the tubes (14a, 14b), to avoid relative displacements.

14. Device (10) according to the preceding claim, wherein the securing of the internal (14a) and external (14b) tubes is obtained thanks to a crimping of the external tube on the internal tube, to the simultaneous bending of the internal and external tubes, or to the welding of the ends of the internal and external ends opposite the connector.

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