FR3067102B1 - PROCESS FOR PRODUCING A HEAT EXCHANGER - Google Patents

Abstract

The present invention relates to a method of manufacturing a heat exchanger (1) comprising: a beam (2) of tubes comprising a plurality of tubes (20) arranged parallel to each other and spacers (21) arranged between said tubes (20), ° a collecting plate (4) comprising holes (43) into which ends (22) of the tubes (20) are introduced, the collecting plate (4) comprising at least one seal (41) compressible first compressible collars (45), the first compressible collars (45) being inserted into the holes (43) and compressed between the wall of the holes (43) and the ends (22) of the tubes (20) to provide the sealing between said ends (22) of the tubes (20) and the collector plate (4), said manufacturing method comprising a quenching step applied at least on the ends (22) of the tubes (20).

Description

The invention relates to a method for manufacturing a heat exchanger, in particular a mechanical heat exchanger or mechano-brazed.

Heat exchangers generally comprise a multiplicity of tubes between which spacers, hereinafter called spacers, are inserted in order to form a bundle of tubes. The tubes are generally tubes of oval or oblong section, defined by a major axis and a minor axis, and having ends inserted into holes of a header plate. A first type of heat exchanger is represented by so-called brazed heat exchangers where the tubes and the spacers are fixed to each other by brazing in order to form the bundle of tubes and where the sealing between the ends of the tubes and the collector plate is also provided by brazing the tubes in the holes of said collector plate. A second type of heat exchanger is represented by so-called mechanical heat exchangers, where the tubes and the fins are mechanically fixed between them in order to form the bundle of tubes, for example by crimping, and where the sealing between the ends tubes and the header plate is also provided by a seal disposed in the holes of said header plate. There is also a third type of heat exchanger represented by the so-called mechanically-brazed heat exchangers, where the tubes and spacers are brazed together to form the bundle of tubes and where the seal between the ends of the tubes tubes and the header plate is also provided by a seal disposed in the holes of said header plate.

In the case of a brazed heat exchanger, the connection between the tubes and the collector plate is rigid and can not compensate for the expansion and retraction phenomena related to temperature variations during its use. Over time, these connections become fatigued and breaks or leaks can occur.

In the case of a mechanical or mechanically-brazed heat exchanger, the seal between the collector plate and the ends of the tubes is formed by a compressible seal. This same seal makes it possible to absorb the phenomena of expansion and shrinkage related to temperature variations during the use of the heat exchanger. However, the tubes must be able to withstand the pressure exerted by the seal and therefore said tubes must be sufficiently thick, which unfortunately can adversely affect the quality of heat exchange.

One of the aims of the present invention is therefore to at least partially overcome the disadvantages of the prior art and to provide an improved method of manufacturing a heat exchanger.

The present invention therefore relates to a method of manufacturing a heat exchanger comprising: a tube bundle comprising a plurality of tubes arranged parallel to each other and spacers arranged between said tubes, a collector plate comprising holes in which tube ends are introduced, the manifold plate having at least one compressible seal forming first compressible collars, the first compressible collars being inserted into the holes and compressed between the wall of the holes and the ends of the tubes to ensure the sealing between said ends of the tubes and the collector plate, said manufacturing method comprising a quenching step applied at least on the ends of the tubes.

This quenching step allows the tubes, and more precisely their ends, to withstand the pressure exerted by the compressible seal, especially during expansion and retraction phenomena.

According to one aspect of the process according to the invention, the quenching step is carried out after a brazing step of the tubes.

According to another aspect of the process according to the invention, the step of brazing the tubes is a brazing step of the tubes and spacers so as to form a bundle of brazed tubes.

According to another aspect of the method according to the invention, only the ends of the tubes undergo a quenching step and in that the height of the zone of said ends undergoing said quenching step is greater than the height of the zone of said ends which is intended to come into contact with the first compressible collars.

According to another aspect of the process according to the invention, the tubes are made of aluminum alloy of series 2000, 6000 or 7000.

According to another aspect of the process according to the invention, the quenching step comprises: a first substep of rapid cooling of at least the ends of the tubes while said ends have a temperature greater than 450 ° C., second substep of income at a temperature between 90 and 110 ° C for a period of 30 to 60min.

According to another aspect of the process according to the invention, the first rapid cooling sub-step is carried out by dipping in water. Other features and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and nonlimiting example, and the appended drawings among which: FIG. 1 shows a schematic representation in perspective of FIG. 2 shows a diagrammatic representation in perspective and in longitudinal section of the heat exchanger of FIG. 1; FIG. 3 shows a flowchart of the manufacturing process of the heat exchanger according to FIG. 'invention.

The identical elements in the different figures bear the same references.

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments may also be combined or interchanged to provide other embodiments.

In the present description, it is possible to index certain elements or parameters, such as for example first element or second element as well as first parameter and second parameter or else first criterion and second criterion, etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria close but not identical. This indexing does not imply a priority of one element, parameter or criterion with respect to another, and it is easy to interchange such denominations without departing from the scope of the present description. This indexing does not imply either an order in time for example to appreciate such or such criteria. The heat exchanger 1 shown in Figures 1 and 2, comprises a beam 2 formed of a plurality of tubes 20 inside which can circulate a first heat transfer fluid. The tubes 20 are arranged parallel to each other. Between the tubes 20 are placed tabs 21 which act as a disrupter and increase the heat exchange surface with a second heat transfer fluid passing between said tubes 20. As shown in FIGS. 1 and 2, the tubes 20 have a cross-section of oblong shape that can be defined along two axes of different lengths.

The tubes 20 and the spacers 21 are made of metal materials. The tubes 20 and the spacers 21 forming the beam 2 can be fixed together mechanically. In this case, the spacers 21 are called fins. The fins comprise plates placed perpendicularly to the tubes 20. Said fins comprise orifices in which the tubes 20 are inserted and fixed. The fixing of the tubes 20 is said to be mechanical, for example by widening said tubes 20 by means of a size olive. greater than that of the tubes 20 which is inserted into the tubes 20 to increase their size and then removed. This is called mechanical beam 2. On the other hand, the tubes 20 and the spacers 21 forming the bundle 2 can be fixed together by brazing. In this case and as illustrated in Figures 1 and 2, the spacers 21 may be what are called tabs. These spacers are for example corrugated or crenellated strips, placed between the tubes 20 and fixed to said tubes 20 by soldering. This is called a brazed beam 2.

The tubes 20 may also have within them a leg 26 of tube connecting the widest inner walls of the tubes 20. This leg 26 of tube allows good rigidity of said tubes 2O.Une such leg 26 may in particular be present in tubes 2 formed by a plate folded on itself and brazed so as to form the tube 2. The heat exchanger 1 also comprises two collectors or water boxes disposed at each end 22 of the tubes 20. These collectors comprise a collector plate 4 and a cover (not shown) covering said collector plate 4 and close the collector. These collectors allow the collection and / or distribution of the first coolant so that it circulates in the tubes 20. The manifold plate 4 makes the connection sealingly between the collector and the beam 2.

The header plate 4 comprises a core 40, which may be of generally rectangular shape, delimiting a multiplicity of holes, of section corresponding to the shape of the section of the tubes 20 and adapted to receive the ends 22 of the tubes.

According to an embodiment illustrated in Figures 1 and 2, each hole may be bordered by a collar 44, in particular directed towards the beam 2. The holes are similar in size to the openings of the collars 44. The collars 44 may advantageously come from material with the collector plate 4 and be formed, for example, at the same time as the holes 43 by stamping.

The holes 43 and the flanges 44 have a shape corresponding to that of the cross section of the tubes 20, or at least their ends 22, and since this shape is generally oblong, it is possible to characterize said holes 43 and said flanges 44 according to two axes of different lengths.

As shown in Figure 2, the core 40 may be extended by a peripheral groove 42 ending in a peripheral flange 46 forming foldable legs. The peripheral groove 42 is intended to receive the rims of the lid and the peripheral rim 46 can be folded and folded down in order to fix said lid on the collector plate 4.

The header plate 4 receives at least one compressible sealing gasket 41, in particular to allow sealing at the holes 43.

As shown in Figure 2, the header plate 4 may have only one compressible seal 41. This seal 41 comprises a core coming to apply to the core 40 of the header plate 4. This core of the seal 41 is connected to a multiplicity of first compressible collars 45 which are each introduced into a hole 43. At assembly of the bundle 2 with the header plate 4, the first compressible collars 45 are compressed between the wall of the holes 43 and the ends 22 in order to seal between said ends 22 of the tubes 20 and the header plate 4. Furthermore, the core of the seal 41 may form at its periphery a bead 47 disposed in the peripheral groove 42 and adapted to seal with the lid when the peripheral flange 46 is folded.

According to a variant not shown, the header plate 4 may comprise a plurality of compressible seals 41 which form first compressible collars 45 which are each introduced into a hole 43 to seal between the end 22 of a In this embodiment, the seal with the lid can be made by an independent compressible seal and placed in the peripheral groove 42. The use of a seal 41 single compressible or a plurality of compressible seals 41 to achieve the connection between the beam 2 and the collector plate 4, allows a certain flexibility of the connection that can absorb the expansions and shrinkage related to temperature changes. The connection between the beam 2 and the collector plate 4 is therefore more resistant to these temperature variations.

The first compressible collars 45 also have a shape corresponding to that of the cross section of the tubes 20, or at least their ends 22. It is therefore also possible to characterize said first compressible collars 45 along two axes of different lengths.

The ends 22 of the tubes 20 may also include at least one flaring 25, inside the collectors and box, which overcomes the compressible seal 41 as illustrated in FIGS. 1 and 2. This flaring 25 may in particular be realized on a limited portion of the ends 22 of the tubes 20. This flaring 25 allows in particular the locking and holding in place of the manifold plate 4 on the beam 2. In the example shown in Figures 1 and 2, the ends 22 of the tubes 20 each comprise two flares 25 made on a limited portion.

So that the tubes 20 and more precisely their ends 22 withstand the pressure exerted by the compressible seal 41, especially during the expansion and retraction phenomena, at least said ends 22 may undergo a curing heat treatment.

The manufacturing process of the heat exchanger 1, illustrated in FIG. 3, then comprises a quenching step 102 applied at least on the ends 22 of the tubes 20.

This quenching step 102 is in particular carried out after a step 101 of brazing the tubes 20 in order to take advantage of the fact that the tubes 20 are still hot and thus to avoid an additional step of heating the tubes 20.

According to a first embodiment of the manufacturing method, the brazing step 101 can in particular be a brazing step of the tubes 20 and the spacers 21 so as to form a bundle 2 of brazed tubes 20.

For this first embodiment, preferably only the ends 22 of the tubes 20 undergo a quenching step in order to avoid treating the entire brazed beam 2. As a result, the height of the zone of said ends 22 undergoing the quenching step is greater than the height of the zone of said ends 22 which is intended to come into contact with the first compressible collars 45.

According to a second embodiment of the manufacturing method, the brazing step 101 can be a soldering step for the formation of the tube 20 itself, for example the brazing of a folded metal sheet on itself and whose edges are brazed to form a tube 20.

For this second embodiment, the tube 20 in its entirety or only its ends 22 can undergo a quenching step.

The tubes 2 are preferably made of aluminum alloy series 2000, 6000 or 7000. These aluminum alloys have good thermal conductivity and also have the ability to harden by precipitation and therefore can undergo a quenching step in order to increase their mechanical resistance.

For these aluminum alloys, the quenching step 102 may in particular comprise: a first sub-step 102a for rapid cooling of at least the ends 22 of the tubes 20 whereas said ends 22 have a temperature greater than 450 ° C. , preferably greater than 500 ° C, a second substep 102b of income at a temperature between 90 and 110 ° C for a period of 30 to 60min.

The first sub-step 102a of rapid cooling can in particular be carried out by dipping in water, for example at a temperature of the order of 20 ° C. However, any means of rapid cooling can also be used during this first sub-step, for example a projection of water on the desired zone or zones, or a forced convection of ambient air, cooled air or a drizzle.

Thus, it can clearly be seen that the heat exchanger 1 according to the invention makes it possible to have tubes 20 whose walls are thin enough to have optimal heat exchange and this while being able to withstand the pressures exerted by a tightness between the tubes. 20 and the collector plate 4 made by means of a compressible seal 41.

Claims (7)

A method of manufacturing a heat exchanger (1) comprising: a bundle (2) of tubes having a multiplicity of tubes (20) arranged parallel to each other and spacers (21) disposed between said tubes (20); A collector plate (4) comprising holes (43) in which ends (22) of the tubes (20) are introduced, the collector plate (4) comprising at least one compressible seal (41) forming first compressible collars (45), the first compressible collars (45) being inserted into the holes (43) and compressed between the wall of the holes (43) and the ends (22) of the tubes (20) to seal between said ends (22) of the tubes (20) and the collector plate (4), said manufacturing method comprising a quenching step applied at least on the ends (22) of the tubes (20). 2. Manufacturing process according to claim 1, characterized in that the quenching step is performed after a brazing step of the tubes (20). 3. The manufacturing method according to claim 2, characterized in that the soldering step of the tubes (20) is a soldering step of the tubes (20) and spacers (21) so as to form a beam (2) of tubes (20) brazed. 4. Manufacturing method according to the preceding claim, characterized in that only the ends (22) of the tubes (20) undergo a quenching step and in that the height of the zone of said ends (22) undergoing said quenching step is greater than the height of the area of said ends (22) which is intended to come into contact with the first compressible collars (45). 5. Manufacturing process according to one of the preceding claims, characterized in that the tubes (2) are made of aluminum alloy series 2000, 6000 or 7000. 6. Manufacturing process according to the preceding claim, characterized in that the quenching step comprises: a first substep of rapid cooling of at least the ends (22) of the tubes (20) while said ends (22); ) have a temperature above 450 ° C, a second substep of tempering at a temperature between 90 and 110 ° C for a period of 30 to 60min. 7. Manufacturing process according to the preceding claim, characterized in that the first sub-stage of rapid cooling is carried out by dipping in water.