FR3139190A1 - Fluid connection system for a heat exchanger - Google Patents

Abstract

Fluid connection system for a heat exchanger The present invention relates to a connection system (20) for a heat exchanger, the connection system comprising: - a metallic structure comprising a fluid inlet or outlet orifice, - a tubing (34) mounted watertight on the metal structure, forming a connection with the fluid inlet or outlet orifice, the system being characterized in that the tubing (34) comprises a base portion (346) proximal to the metal structure, and a connection portion (348) connected to the base portion (346), the connection portion (348) being of smaller section than that of the base portion (346). (figure 5)

Description

Fluid connection system for a heat exchanger

The present invention relates to the field of cooling circuits in particular for motor vehicles and relates more precisely to a fluid inlet or outlet connection system making it possible to connect a heat exchanger to such a circuit.

The heat exchangers fitted to the air conditioning loops of vehicles are arranged to allow the adjacent circulation in two separate spaces of two different fluids, so as to carry out a heat exchange between these fluids, without mixing them. Within the heat exchangers and the thermodynamic circuits to which they are attached, the fluids circulate under pressure.

Such an exchanger 2 is shown on the . It is made up of a bundle of heat exchange plates and fluidic connections 8, 10 connecting this bundle to the circuits with which the exchanger is connected. While the harness is standard for use in many vehicles, the fluid connections are specific to each cooling system design intended for a particular vehicle model.

Currently, the fluidic connections 8 intended for the refrigerant fluid circulating in such an exchanger form an aluminum connection block brazed on a cheek 6 of the exchanger 2, this cheek being an external metal plate of the exchanger 2 bordering the bundle of plates , itself arranged in an aluminum casing 4. On the , the fluid connections 8 are cylindrical orifices in the connection block, into which hoses with an aluminum end piece fitted with a seal are inserted. This connection block can be adapted to a specific cooling circuit of a vehicle, in particular the arrangement of the orifices in the connection block can be different.

A disadvantage of the exchanger described above lies in a problem of homogeneity of distribution of the refrigerant fluid between the channels, delimited by the plates, which are directly adjacent to the connection block compared to the channels which are distant from the connection block.

Furthermore, the current manufacture of the connection blocks of such heat exchangers requires heavy and complex brazing tools, in particular for brazing together the bundles of such heat exchangers with their connection blocks, due to the size of the brazing furnace. necessary, brazing supports which must be adapted to the different locations and connection blocks to allow their assembly on the beams. The number of plates in the bundle is then limited to allow flat brazing of the device.

These different constraints degrade the homogeneity of the thermal performance of such a heat exchanger.

There is therefore a need for a simple and easy to implement technical solution, a refrigerant fluid connection block on a heat exchanger, which allows the channels immediately adjacent to the connection block to be correctly supplied. Such a block also facilitates the adaptation of the orifices of the connection block to the different orifices of the heat exchanger collectors and to the specificities of the cooling circuits of different vehicle models.

The present invention at least partly remedies the drawbacks of the prior art, by providing a connection system for a heat exchanger, and a heat exchanger, which allow great freedom of design of the fluidic connections of the heat exchanger. while improving thermal homogeneity within this heat exchanger.

To this end, the invention proposes a connection system for a heat exchanger, the connection system comprising:
- a metal structure comprising a fluid inlet or outlet orifice,
- a tube mounted watertight on the metal structure, forming a connection with the fluid inlet or outlet port,
the system being characterized in that the tubing comprises a base portion proximal to the metal structure, and a connection portion connected to the base portion, the connection portion being of smaller section than that of the base portion.

By “proximal” we mean here that the base portion is closer to the metal structure than the connection portion, which is intended to receive a hose tip.

Thanks to the invention, a pre-chamber is formed in the tubing, which can be easily machined when the tubing is made of synthetic material, because although the base portion and the connection portion are of different internal sections, these internal sections can be each of constant or substantially constant shape until their junction, in other words the shape of the internal section of the tubing does not evolve continuously along the tubing. By “substantially” we mean that the internal section of the base portion or the connection portion only varies by one or two millimeters at most around its shape at the entrance to the portion concerned.

This prechamber is advantageous in the case where the orifice of the collector opposite the tubing has a larger section than that of the connection portion.

Such a prechamber allows distribution of the refrigerant fluid sufficiently upstream of the first channels, so that they are supplied in the same way as the channels furthest from the connection block.

Without this pre-chamber, the sudden widening of the section of the refrigerant circuit at the level of the cheek of the heat exchanger generates poor distribution of the refrigerant fluid at the level of the first plates of the bundle of plates of the heat exchanger . By shifting this widening to the level of the prechamber, the distribution of the refrigerant fluid in the heat exchanger is improved.

The invention applies both to the fluidic connections of the heat exchanger intended for the heat transfer liquid of the heat exchanger and to the fluidic connections of the heat exchanger intended for the refrigerant fluid, although the invention is more specifically intended for the latter option.

According to an advantageous characteristic of the invention, the base portion has an internal contour substantially identical to the contour of the fluid inlet or outlet orifice. This characteristic makes it possible to limit pressure losses. By “substantially” we mean that the internal contour of the base portion overlaps the fluid inlet or outlet orifice to within one or two millimeters.

Preferably, the base portion extends over a height of between 2.5 and 13 millimeters, which optimizes the circulation of the fluid in the heat exchanger. It is for example of triangular or rectangular section. The connection portion is for example of circular section. This facilitates its connection to a hose.

In an exemplary embodiment, the base portion comprises at least one groove receiving a sealing member, for example a seal.

According to an alternative embodiment, this groove is replaced by an overmolding of elastomeric material, acting as a sealing member.

According to an advantageous characteristic of the invention, the tubing of the connection system according to the invention comprises at least one ear, and the connection system according to the invention comprises a device for maintaining the tubing in compression against the metal structure, the device for maintaining compression comprising at least one stud passing through the ear and secured to the metal structure, and at least one element for blocking the ear along the stud, the stud comprising at least one housing in which the at least a blocking element is mounted.

Thanks to this characteristic, the heat exchanger is firstly brazed or welded with the metallic structure and the pad(s) of the device maintaining compression, these pads being preferably metallic, then in a second step the tubing is compressed along the pad(s). This allows assembly and disassembly of the tubing elsewhere than on the brazing or welding station and therefore provides flexibility for conditioning the heat exchanger.

In addition, the invention makes it possible to optimize the diameters of the inlet and outlet orifices of the exchanger when these are positioned in the corners of the external metal plate, compared to the solutions of the prior art. In fact, when the tubes are made of synthetic material, they do not need to be brazed onto a side of the heat exchanger, and can be of very diverse shapes.

The connection system according to the invention of course preferably comprises both an inlet pipe and an outlet pipe each associated with a fluid inlet or outlet orifice, and a compression maintenance device associated with each pipe. .

In an exemplary embodiment of the invention, the housing of the stud of the device for maintaining compression of the connection system according to the invention comprises a threaded hole, the blocking element comprising a screw capable of being screwed into the threaded hole passing through an excrescence of a tube intended to be mounted watertight on the tubing. In fact, the tubing is intended to receive an aluminum end piece of a hose. In this example embodiment of the invention, the hose includes a protrusion, for example an ear, in which a screw presses the protrusion against the ear of the tubing by screwing into the threaded hole. The ear of the tubing thus compresses the tubing against the metal structure, ensuring the tightness of the connection system.

Preferably, the stud comprises a circular groove forming the housing, the blocking element being in the form of a clip, the clip comprising two arms, and the ear comprising two through orifices each receiving one of the two arms of the clip , the two arms enclosing the stud while being housed in the circular groove. This embodiment of the invention does not require specific assembly with the hose, but is compatible with the previous embodiment insofar as the device for maintaining compression possibly has several blocking elements housed in several housings of the stud.

Still preferably, the tubing includes another ear, the metal structure comprising another stud secured to the metal structure and passing through the other ear. The device for maintaining compression preferably comprises an element for blocking the other ear along the other stud, the other stud comprising a housing in which the blocking element is housed.

The blocking element is for example a clip or a screw as mentioned above. The other pad is also preferably a metal pad brazed or welded to the metal structure.

In an exemplary embodiment of the invention, the metal structure comprises a side of the heat exchanger and a complementary plate welded or brazed against the side of the heat exchanger, the stud being integral with the complementary plate. This additional plate provides more space for fixing the tubing to the inlet and outlet ports of the collector of the heat exchanger plate bundle. The other stud is for example positioned on a surface of the complementary plate extending beyond the cheek.

Advantageously, the metal structure includes a device for indexing the complementary plate on the cheek and/or the stud on the cheek. This indexing device makes it possible to correctly position the orifices of the complementary plate on those of the heat exchanger cheek, and the tubes on the orifices of the heat exchanger collector.

The indexing device comprises for example at least one collar capable of inserting into a corresponding opening of the complementary plate and/or of receiving the stud.

In one embodiment, the connection system according to the invention comprises an overmolded seal fixed on the cheek of the heat exchanger, on the contour of the fluid inlet or outlet port, this seal molded seal being able to envelop at least partly the base portion of the tubing.

The invention also relates to a heat exchanger comprising at least one bundle of plates and at least one connection system according to the invention.

A method of assembling a connection system according to the invention comprises the steps of:

- securing the stud to the metal structure,
- insertion of the ear of the tubing on the stud,
- compression of the ear along the stud and blocking of the ear via the blocking element.

Other characteristics and advantages of the invention will appear further through the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which :

already commented on in relation to the prior art, illustrates a heat exchanger of the prior art,

represents in perspective a face of a metallic structure of a connection system according to the invention, according to a first embodiment of the invention,

represents in perspective an opposite face of the metal structure of the , in the first embodiment of the invention,

represents in perspective a connection system according to the invention in the first embodiment of the invention,

represents in perspective a tubing of a connection system according to the invention, in the first embodiment of the invention,

represents in perspective a connection system according to the invention in a second embodiment of the invention,

represents in perspective a metallic structure of the connection system of the , And

represents in perspective a tubing of the connection system of the .

According to a first embodiment of the invention represented on the , a connection system 20 according to the invention for a heat exchanger, comprises a metal structure consisting of the cheek 22 of the heat exchanger, closing a bundle of metal plates of the heat exchanger, and a plate complementary 24 welded or brazed on the cheek 22 of the heat exchanger. The cheek 22 and the complementary plate 24 are therefore metallic, for example made of aluminum.

The cheek 22 and the complementary plate 24 have two orifices 30 and 32 intended to overlap the fluid inlet and outlet orifices of the heat exchanger. For example, port 30 is a refrigerant inlet port, and port 32 is a refrigerant outlet port. The orifices 30 and 32 are therefore of identical or substantially identical section to those of the heat exchanger collector. By substantially identical, we mean that the orifices 30, 32 overlap with those of the heat collector to within one or two millimeters.

In order to facilitate the correct superposition of the complementary plate 24 on the cheek 22, particularly at the level of the orifices 30 and 32, an indexing device for the cheek 22 helps to position the complementary plate 24 on the cheek 22. In this first embodiment of the invention, this indexing device comprises two collars 222 and 224 on the cheek 22, being inserted into corresponding orifices of the complementary plate 24. These collars 222 and 224 also serve to position each a metal stud on the complementary plate 24. In this example embodiment, the collar 224 serves to position a stud 28, metallic and secured by brazing or welding, in the collar 224. Another stud 26, metallic, is positioned on the complementary plate 24 thanks to an orifice 25 (visible ) of the complementary plate 24, into which the stud 26 is screwed. Alternatively, the stud 26 is welded or brazed to the complementary plate 24, the orifice 25 only serving to receive an excrescence of the stud 26. In another variant , the studs 26 and 28 come from the material with the complementary plate 24.

In yet another variant, the indexing device comprises for example pins on the cheek 22, which are inserted into corresponding orifices of the complementary plate 24, and the complementary plate 24 comprises a device for positioning the metal stud 28, for example a pawn or a collar.

The studs 26 and 28 serve to position a tube 34 of the connection system 20 according to the invention, shown on the , on the complementary plate 24. For this the tubing 34 has two ears 342 and 344 in which the stud 28 and the stud 26 are inserted respectively. The tubing 34 is preferably made of synthetic material, that is to say from polymers (plastic material). Alternatively, the tubing 34 is made of aluminum or another metal.

In this first embodiment of the invention, a tube such as the tube 34 is mounted in a sealed manner against each fluid inlet or outlet orifice 30, 32. There are therefore in fact four metal studs on the complementary plate 24 to position these two pipes, only the studs 26, 28 and the pipe 34 being represented in Figures 2 to 4. It clearly appears that the two pipes have too much space. important to be mounted together only on the cheek 22 of the heat exchanger, hence the presence of the complementary plate 24 making it possible to receive at least one ear and a stud corresponding to a tube. Thus, the ear 344 and the stud 26 are positioned on a surface of the complementary plate 24 which extends beyond the cheek 22.

It follows that in the case where the fluid inlet and outlet orifices of the heat exchanger make it possible to mount tubing in a sealed manner on these orifices without overflowing from the flat surface of the cheek 22, the plate Additional 24 is not necessary. In this configuration, illustrated in a second embodiment of the invention described below, the metal studs allowing the tubing to be positioned are therefore directly brazed or welded to the cheek 22.

In addition to the ears 342 and 344, the tube 34 includes a base portion 346, as shown in the , and a connection portion 348 extending axially the base portion 346. By axially, we mean in a direction parallel to the longitudinal direction of the pads 26, 28, that is to say to the direction of flow of the refrigerant fluid in the tubing 34.

The base portion 346 is pressed against the complementary plate 24 via a sealing member (not shown), in particular a seal mounted in a groove 345 dug in the contact surface of the base portion 346 with the complementary plate 24. Alternatively, the sealing member is an overmolding made on this contact surface.

The internal section of the base portion 346, along a plane orthogonal to this axial direction, is identical or substantially identical to the shape of the orifice 32, that is to say that the internal section of the base portion 346 and orifice 32 overlap exactly, or within one or two millimeters. This internal section extends over a height, that is to say in the axial direction, of 2.5 to 13 millimeters from the external surface of the base portion 346 on which the sealing member is mounted, up to the connection portion 348.

At the junction between the base portion 346 and the connection portion 348, there is a sudden variation in the internal section of the tubing 34, the internal section of the connection portion 348 being less than the internal section of the base portion 346. In this first embodiment of the invention, the internal section of the base portion 346 is triangular, while the internal section of the connection portion 348 is circular. These internal sections of the connection portion 348 and the base portion 346 are connected by a wall substantially orthogonal to the axial direction, so as to form a prechamber inside the base portion 346. By substantially orthogonal we mean orthogonal with a tolerance of plus or minus five degrees of deviation with a strictly orthogonal direction. This pre-chamber makes it possible to improve the distribution of the refrigerant fluid in the plate bundle of the heat exchanger.

Of course as a variant, the internal section of the base portion 346 is of a different shape, for example rectangular or circular. The connection portion 348 being intended to receive a hose, the end of which is made of aluminum and has a seal, the shape of the section of the connection portion 348 is preferably circular.

In order to ensure sealing between the complementary plate 24 and the tubing 34, the connection system 20 according to the invention comprises a device 40 for maintaining the tubing 34 in compression against the complementary plate 24, as shown in the figure. . This device for maintaining compression 40 comprises, in this first embodiment of the invention, two clips 36 and 38. The arms of each of these clips 36, 38 are housed both in each of the respective ears 344 and 342, and in respective circular grooves 282 and 262 of the studs 28 and 26, these circular grooves being visible on the . To do this, the two arms of each clip 36, 38 are mounted by sliding in two through holes 3442 (visible ) of each of the ears 344 and 342, once these are mounted on the studs 26, 28. Then the free ends of the arms of the clips 36, 38 are folded, as visible on the , which makes it possible to lock the compression support of the tubing 34 on the complementary plate 24.

In addition to this maintenance in compression of the tubing 34 by the clips 36, 38, the device for maintaining compression 40 includes a threaded hole 284 on the stud 28. In fact, the hose connecting to the tubing 34 has a protrusion , for example an ear, which a screw (not shown) of the compression maintaining device 40 passes through by screwing into the threaded hole 284. This screw therefore makes it possible to hold the hose against the tubing 34 which maintains it in compression against the complementary plate 24. In particular, this screw presses the protrusion of the hose against a surface 3422 of the ear 342. The ear 342 extends axially up to the complementary plate 24 to allow this compression of the hose against the ear 342, to compress the ear 342 against the complementary plate 24. An orifice 347 in the ear 342 of the tubing 34 makes it possible to position the protrusion of the hose on the ear 342 angularly to allow this screwing, the protrusion of the hose comprising a positioning pin complementary to this orifice 347.

Of course, the other tubing of the connection system 20, forming a fluid connection with the orifice 30, includes a compression maintaining device similar to the compression maintaining device 40.

Alternatively, the compression holding device 40 comprises only one of the clips 36, 38, or only the threaded hole 284 and the screw for holding the hose against the ear 342, or a threaded hole in each of the studs 26 , 28, these threaded holes each cooperating with a protrusion and a screw holding the hose against the ear 342, or a combination of these possibilities.

We now describe a method of assembling the connection system 20 according to the invention, relative to the first embodiment of the invention, on a bundle of plates of a heat exchanger, relative to the tubing 34 only for simplicity. This process includes the following steps:

The first step is the positioning of the complementary plate 24 on the cheek 22 of the heat exchanger using the collars 222 and 224.

The next step is the positioning of the studs 28, 26 in the collars 222 and 224.

The next step is the brazing of the heat exchanger equipped with the cheek 22 on which the complementary plate 24 and the studs 26, 28 are positioned. For this, the assembly cheek 22, complementary plate 24 and studs 26, 28 is positioned on the heat exchanger plate bundle.

The next step is the positioning of the tubing 34 on the orifice 32 by inserting the studs 28, 26 into the respective ears 344, 342.

The next step is the compression of the ears 344, 342 along the studs 28, 26 and the blocking along these studs 28, 26, of these ears held in compression, by mounting the respective clips 38, 36 in the through holes 3442 of the ears 344 and 342 and in the circular grooves 282 and 262.

The next step is locking this compression support by folding the free ends of the clips 28, 36.

Finally, the last step is possibly a check of the tightness of the connection system 20.

In a variant where there is no complementary plate 24, the first steps are of course the positioning of the studs in the collars 222, 224, then the brazing of the heat exchanger equipped with the cheek 22 and the studs 26 , 28.

Likewise in the variant where the studs 26, 28 are made integrally with the complementary plate 24, we go directly from the step of positioning the complementary plate 24 on the cheek 22 to the brazing step. It is the same if the studs 26, 28 are screwed onto the complementary plate 24 before the latter is positioned on the cheek 22.

According to a second embodiment shown in Figures 6, 7 and 8, a connection system 50 for a heat exchanger comprises a metal structure consisting of the cheek 52 of the heat exchanger, closing a bundle of metal plates of the 'heat exchanger. The connection system 50 also includes a tube 64 mounted on the cheek 52, and forming a watertight connection with an orifice 62 (referenced ) fluid inlet or outlet arranged on the cheek 52.

On the , only one pipe 64 is shown, but the heat exchanger of course preferably comprises at least two pipes, a fluid inlet pipe and a fluid outlet pipe, conforming to the connection system 50 according to the invention.

As in the first embodiment of the invention, the tubing 64 comprises a base portion 646, and a connection portion 648 extending axially the base portion 646, that is to say parallel to the flow direction of the refrigerant fluid at the outlet of the cheek 52. The structural characteristics of the base portion 646 and the connection portion 648 are similar to those of the tubing 34 of the first embodiment of the invention and are therefore not further explained. detailed here.

Unlike the first embodiment, in this second embodiment of the invention, the positioning of the tubing 64 on the cheek 52 is achieved by nesting at least part of the base portion 646 of the tubing 64 in a joint overmolded seal 54 fixed on the contour of the orifice 62 of the cheek 32. This overmolded seal 54 extends axially the contour of the orifice 62 by flaring slightly to closely surround the base portion 646 of the tubing 64 on at least part of it in the axial direction. The overmolded seal 54 therefore has a section, orthogonal to the axial direction, of shape complementary to the section of the base portion 646, here a triangular section.

The base portion 646 is pressed against an internal surface of this overmolded seal 54, in particular against a groove 644 (visible ) dug into the contact surface of the base portion 646 with the overmolded seal 54.

Furthermore, in this second embodiment of the invention, the connection system 50 comprises a stud 58 brazed on the cheek 52 and extending orthogonally to the main extension dimension of the cheek 52, that is to say i.e. axially, towards the outside of the cheek 52. A collar 522 arranged on the cheek 52 makes it possible to position the stud 58 before brazing it onto the cheek 52. When positioning the tubing 64 in the overmolded seal 54 , the stud 58 is inserted in an ear 642 of the tubing 64. The stud 58 also includes a threaded hole 584 intended to receive a screw (not shown) passing through a protrusion of a hose connecting to the tubing 64. This screw maintains the protrusion in compression against a surface 6422 of the ear 642, which compresses the ear 642 and therefore the tubing 64 against the cheek 52.

An orifice 647 in the ear 642 of the tubing 64 makes it possible to position the protrusion of the hose angularly on the ear 642 to allow this screwing, the protrusion of the hose comprising a positioning pin complementary to this orifice 647.

The stud 58 and the screw therefore constitute, in the connection system 50 according to the invention, a device for maintaining the tubing 64 in compression against the cheek 52.

In this second embodiment, only one stud 58 per tube 64 of the connection system 50 according to the invention is necessary, and the device for maintaining compression only uses the screw associated with the hose connecting to the tube 64 .

In this second embodiment of the invention, a method of assembling the connection system according to the invention on a bundle of plates of a heat exchanger, relative to the tubing 64 comprises the following steps:

The first step is the positioning of the stud 58 in the collar 522.

The next step is the brazing of the heat exchanger equipped with the cheek 52 on which the stud 58 is positioned. For this, the cheek assembly 52 and stud 58 is positioned on the bundle of plates of the heat exchanger .

The next step is the positioning of the overmolded seal 54 on the cheek 52.

The next step is the positioning of the tubing 64 against the orifice 62 by fitting the tubing 64 into the overmolded seal 54 and inserting the stud 58 into the ear 642.

The next step is the compression of the ear 642 along the stud 58 and the blocking along this stud 58 of the ear 642 held in compression, by screwing a screw held in an excrescence of a hose in the hole threaded 584 of the stud 58 and connecting the hose into the tubing 64.

Finally, the last step is possibly a check of the tightness of the connection system 50.

Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

Claims (10)

Connection system (20) for a heat exchanger, the connection system (20) comprising:
- a metal structure (22, 24) comprising a fluid inlet or outlet orifice (32),
- a tube (34) mounted watertight on the metal structure (22, 24), forming a connection with the fluid inlet or outlet orifice (32),
the system being characterized in that the tubing (34) comprises a base portion (346) proximal to the metal structure (22, 24), and a connection portion (348) connected to the base portion (346), the connection portion (348) being of smaller section than that of the base portion (346). Connection system (20) according to claim 1, in which the base portion (346) has an internal contour substantially identical to the contour of the fluid inlet or outlet orifice (32). Connection system (20) according to claim 1 or 2, in which the base portion (346) extends over a height of between 2.5 and 13 millimeters. Connection system (20) according to any one of the preceding claims, in which the base portion (346) is of triangular or rectangular section. Connection system (20) according to any one of the preceding claims, in which the connection portion (348) is of circular section. Connection system (20) according to any one of the preceding claims, in which the base portion (346) comprises at least one groove (345) receiving a sealing member. Connection system (20) according to any one of the preceding claims, in which the tubing (34) comprises at least one ear (342, 344), and the connection system (20) comprises a compression maintaining device (40). ) of the tubing (34) against the metal structure (22, 24), the compression holding device (40) comprising at least one stud (28, 26) passing through the ear (342, 344) and secured to the structure metal (22, 24), and at least one blocking element (38, 36) of the ear (342, 344) along the stud (28, 26), the stud (28, 26) comprising at least one housing (284, 282, 262) in which the at least one blocking element (38, 36) is mounted. Connection system (20) according to the preceding claim, in which the housing (284) comprises a threaded hole, the blocking element comprising a screw capable of being screwed into the threaded hole passing through a protrusion of a tube intended to be mounted watertight on the tubing (34). Connection system (20) according to claim 7 or 8, in which the stud (28, 26) comprises a circular groove (282, 262) forming the housing (282, 262), the blocking element (38, 36) being in the form of a clip (38, 36), the clip (38, 36) comprising two arms, and the ear (342, 344) comprising two through orifices (3442) each receiving one of the two arms of the clip (38, 36), the two arms enclosing the stud (28, 26) while being housed in the circular groove (282, 262). Heat exchanger comprising at least one bundle of plates and at least one connection system (20) according to any one of the preceding claims.