FR3066015A1 - HEAT EXCHANGER TUBE AND THERMAL HEAT EXCHANGER - Google Patents

Abstract

The heat exchanger tube (5) is made from a web of material (11), the web of material (11) having two end portions connected to form the tube (5). The strip of material (11) forming the tube (5) is folded on itself, so as to define at least one fold (13) formed by two strip portions (13a, 13b) in continuity of material. At least one band portion (13a, 13b) of the fold (13) is a protective band portion (13a, 13b) of the tube (5) in case of impact of an element outside the tube (5), and is made in an intermediate portion (11b) of the material web (11).

Description

Tube for heat exchanger and corresponding heat exchanger The invention relates to a tube for heat exchanger, in particular for motor vehicles. The invention also relates to a heat exchanger comprising a bundle of such tubes. The invention relates to the field of heat exchangers, in particular for motor vehicles.

The present invention relates in particular to heat exchangers intended to be arranged on the front face of a motor vehicle. A front panel, also called the front panel, is a structural element capable of integrating various vehicle equipment, such as headlights, turn signals, horn, heat exchangers, motor-fan unit or cooling module. The heat exchanger is for example used for cooling the engine or for air conditioning the passenger compartment. Generally, heat exchangers conventionally comprise a bundle of tubes and manifolds into which open the ends of the bundle tubes, so as to allow the circulation of a fluid, in particular a cooling fluid, in the bundle tubes.

The tubes of such exchangers can be produced for example by extrusion. However, this type of manufacturing generates a significant cost, in particular because of the need for specific dies for each type of tube.

As a variant, the tubes are produced from a strip of material, for example, by folding the strip of material.

However, heat exchanger tubes can be subjected to many stresses such as high speed impact with an object (for example, gravel) from the outside environment. The heat exchanger tubes are therefore subjected to external stresses. Since the fluid does not have to escape from the tubes of the heat exchangers, at the risk of compromising the operation of these heat exchangers, it is necessary to maintain the sealing of the tubes between the exterior and the fluid.

In order to protect these heat exchangers, a grid, generally made of plastic, can be integrated on the front face to stop the gravel. However, the integration of such a grid at the front face generates a certain cost.

It is useful to guarantee sufficient material resistance at the tube level, in order to avoid any risk of leakage of the heat exchanger fluid, for example in the event of an impact with a gravel on the road.

A known solution is to allow the tube to resist such an impact by locally increasing the thickness of the wall of the tube when it is an extruded tube. However, such tubes are expensive to manufacture. In addition, it has been found that these tubes are less resistant to corrosion compared to tubes made from a strip of material, in particular by bending.

In a first known tube made from a strip of material, the end parts of the tube are folded and joined together by brazing, at one side or nose of the tube. Such brazed folds at the end portions require complicated manufacturing.

In addition, such tubes may not be sufficiently resistant to impact with gravel.

Thus, an objective of the invention is to propose a solution for a tube produced from a strip of material, offering the tube an improved resistance to external stresses in a simple manner, by at least partially solving the drawbacks mentioned above of the prior art. To this end, the subject of the invention is a heat exchanger tube produced from a strip of material, the strip of material having two end parts connected so as to form the tube. According to the invention, the strip of material forming the tube is folded on itself, so as to define at least one fold formed by two portions of strip in continuity of material, such as at least one portion of strip of the fold: - is a portion of the protective strip of the tube in the event of an impact from an element external to the tube, and - is produced in an intermediate part of the strip of material.

The two portions of strips of said at least one ply can be produced in the intermediate part of the strip of material.

In other words, the intermediate part of the strip of material is by definition distinct, that is to say does not include, the lateral ends of the strip of material.

The end portions of the material strip, each include a lateral end of the material strip.

One can for example define the intermediate part of the strip of material as the central part corresponding to 80% of the width of the strip of material, the end parts corresponding for example to the parts having a width of 10% on each side of the middle part.

However, this 80% value is purely indicative. What is important is that the intermediate part does not include the lateral ends of the strip of material.

Furthermore, the intermediate part has a longitudinal extension corresponding to the longitudinal extension of the tube.

Thus, advantageously at places of strong stresses, in particular external to the tube, one or more folds of the tube are created using this or these folds, making it possible to absorb energy in the event of an impact of an element. from the outside environment, such as gravel.

The fold or folds are not produced at the level of a zone of connection or overlapping of the walls of the strip of material requiring sealing, but the wall is folded on itself in continuity of material. Thus, even if the folds would deform, unfold, the sealing of the tube, otherwise carried out for example by brazing or electrofusion, would remain assured. The invention thus has the advantage of protecting the junction between the end parts of the strip of material, and therefore the sealing of the tube.

Said tube may further include one or more of the following characteristics, taken separately or in combination.

Preferably, the intermediate part does not include a junction zone between the two end parts to close the tube tightly. In other words, the intermediate part is devoid of such a junction zone.

According to one aspect of the invention, said at least one fold is formed along at least one lateral side of the tube. This side is configured to be arranged on the front side of a heat exchanger opposite an inlet of an external air flow on the front face of a motor vehicle.

According to an exemplary embodiment, the tube has two large sides connected by two small lateral sides. Said at least one fold is formed on a small lateral side.

According to another aspect of the invention, the strip portions of said at least one plus are brazed together so as to increase the mechanical strength of the tube.

The strip portions of said at least one ply may or may not be leaned against each other.

According to a first embodiment, the strip of material is folded so as to form a protrusion extending from the tube towards the outside of the tube.

Such a protrusion is the first surface of the tube with which a gravel, for example, comes into contact in the event of an impact. The growth can bend and / or deform, under the effect of the impact and thus absorb the energy of the gravel.

Finally, such a tube can be produced in a simple manner without requiring several manufacturing steps. The protuberance may have a thickness at least equal to twice the material thickness of the strip of material.

For example, the protuberance forms with the horizontal a non-zero angle, in particular less than or of the order of 45 °, preferably of the order of 30 °. The protuberance can extend over a width equal to at least twice and at most ten times the material thickness of the strip of material.

According to a second embodiment, the strip of material is folded in the direction of the height of the tube, so as to form an extra thickness of material.

Sufficient extra thickness is obtained, advantageously provided at the level of the tube nose, to guarantee mechanical strength and thus protect the tube in the event of impacts from the external environment, without risk of fluid leakage.

The height of the strip portions of said at least one ply is for example of the order of the height of the tube.

In one or the other embodiment, the tube is a bent tube. The tube may have a cross section substantially at "B", defining two parallel fluid circulation channels, delimited by a partition.

The tube can be an electro-welded tube. The invention also relates to a heat exchanger, in particular for a motor vehicle, characterized in that it comprises a bundle of tubes as defined above. Other characteristics and advantages of the invention will appear more clearly on reading the following description, given by way of illustrative and nonlimiting example, and of the appended drawings among which: - Figure 1 partially and schematically shows a heat exchanger, - Figure 2 is a cross-sectional view partially showing a first example of the exchanger tube of Figure 1, - Figure 3 is a cross-sectional view of a second example of the exchanger tube of Figure 1, - Figure 4 is a cross-sectional view of a third example of the exchanger tube of Figure 1, and - Figure 5 is a cross-section of a fourth example of tube the exchanger of figure 1.

In these figures, identical elements have the same references.

The following embodiments 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 characteristics apply to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments.

In the description, it is possible to index certain elements, such as for example first element or second element. In this case, it is a simple indexing to differentiate and name similar but not identical elements. This indexing does not imply a priority of one element over another and one can easily interchange such names without departing from the scope of this description. This indexing does not imply an order in time either.

FIG. 1 shows schematically an example of a heat exchanger 1 according to the invention. It is in particular a heat exchanger 1 intended to be arranged on the front face of a motor vehicle.

Examples include engine cooling radiators or even so-called low temperature radiators for example for auxiliary cooling circuits in the motor vehicle. It can also be for example a condenser of an air conditioning loop. The heat exchanger 1, such as a cooling radiator, placed on the front face of the vehicle can be reached by a first fluid, such as an external air flow, coming from outside the vehicle. A second fluid, such as a cooling fluid, circulates inside the heat exchanger 1 so as to exchange heat with this external air flow. The heat exchanger 1 has a front side A, that is to say intended to be arranged on the side of the grille of the motor vehicle, or else facing an inlet of the external air flow intended to pass through the heat exchanger 1. The heat exchanger 1 also has a rear side B, or engine side, which is opposite to the front side A.

In the present description, the terms front / rear are designated with reference to the direction of progression in forward gear of the motor vehicle intended to be equipped with a heat exchanger 1 as described. Likewise, the terms vertical / horizontal are designated with reference to the arrangement of the elements in FIGS. 2 to 5, which corresponds to the arrangement of the elements in the mounted state in the motor vehicle.

As is partially illustrated in FIG. 1, the heat exchanger 1 conventionally comprises a bundle 3 (shown very schematically in FIG. 1) of tubes 5.

Examples of tubes 5 are partially shown in Figures 2 to 5. These tubes 5 are mounted between two distribution boxes or manifolds 7, also called water boxes, (also referring to Figure 1) of the second fluid. In the mounted state in the motor vehicle, the heat exchanger 1 can be arranged so as to allow for example a transverse circulation of fluid in the tubes 5 which extend transversely to the motor vehicle. However, there are configurations in which the circulation takes place vertically in vertical tubes.

Advantageously, the heat exchanger 1 is a so-called brazed exchanger. In this case, the various constituents of the body of such a heat exchanger 1 are metallic and can be assembled and then brazed by passing through a brazing furnace, in order to ensure the joining of all the constituents. Note that other plastic elements in particular are typically attached to it after brazing, such as for example water boxes.

The tubes 5 (FIGS. 2 to 5) can extend longitudinally along a length l_5 shown diagrammatically in FIG. 1. The ends of these tubes 5 open into the manifolds 7, for example by means of collector plates (not shown) which can be arranged transversely to the tubes 5.

Each tube 5 defines one or more circulation channels 9 (see FIGS. 2 to 5) for the second fluid.

The tubes 5 can be separated from each other by spacers (not shown), for example corrugated, traversed by the first fluid, such as the external air flow, for a heat exchange with the second fluid, such as the fluid cooling circulating in the tubes 5.

According to an alternative embodiment, not shown, an internal spacer, for example corrugated, can be inserted in the or each circulation channel 9. This internal spacer has for example a thickness of the order of 80 pm to 140 pm. The invention relates more precisely to a tube 5 for such a heat exchanger 1, examples of which are shown diagrammatically in FIGS. 2 to 5.

The tube 5 is produced from a strip of material 11. It is in particular a strip 11 of metal. The metal strip is preferably made of aluminum or an aluminum alloy. The strip of material 11 is for example of generally rectangular shape.

This strip of material 11 has a thickness e, also called hereinafter material thickness. This material thickness e is constant. For example, the material thickness e can be of the order of 180 pm to 270 pm, in particular of the order of 200 pm to 270 pm.

In particular, the tube 5 can be obtained from a coil of metal foil which, as a result of its unwinding in a strip, is gradually shaped to the desired cross section by specific tools, for example bending or the like, then cut to the desired length, in sections corresponding to several final tubes 5.

In particular, the strip of material 11 has end portions 11a, visible in the example of FIG. 4, which are connected to form the tube 5, in particular for sealing the tube 5. These end parts 11a comprise the lateral ends or lateral edges of the strip of material 11. The seal can be ensured by brazing at the junction of the end parts 11a. Alternatively, it may be an electro-welded tube 5.

The strip of material 11 also has an intermediate portion 11b. This intermediate part 11b does not include the lateral ends of the strip of material 11. The intermediate part 11b is separate from the end parts 11a. By way of nonlimiting example, the end portions 11a of the strip of material 11 may extend on each side of the strip of material 11 over a width of the order of 10% each of the total width of the strip of material 11.

The intermediate part 11b forms a central part extending for example over a width of the order of 80% of the total width of the strip of material 11.

Furthermore, the end parts 11a and the intermediate part 11b each have a longitudinal extension corresponding to the longitudinal extension of the tube 5.

The tube 5 can be bent or shaped so as to define a single fluid circulation channel 9 (FIG. 3). By way of nonlimiting example, the tube 5 may have a generally oblong cross section. The strip of material 11 then forms an envelope of this circulation channel 9.

Alternatively, the tube 5 can be folded or shaped so as to define or at least two circulation channels 9 (Figure 4). The tube 5 may have a so-called “B” cross section.

The cross-section at "B" of the tube 5 illustrated, has two parallel fluid circulation channels juxtaposed 9 and separated by a partition forming a spacer. To this end, the metal strip is folded back so as to form the envelope of these juxtaposed parallel circulation channels 9. The partition is produced jointly by the opposite folded end portions 11a of the strip of material 11. In this example, the intermediate portion 11b of the strip of material 11 does not include the junction zone Z, surrounded by dotted lines on the Figure 4, two end portions 11a to form the partition.

Here we have described a tube bent at "B". Of course, any other type of folding can be provided.

The end portions 11a of the strip of material 11, only visible in the example of FIG. 4, can be leaned or superimposed one against the other. In particular, in the example of FIG. 4, the end parts 11a can be folded, for example substantially at right angles, and leaned against each other.

According to one or other of the variants represented in FIGS. 2 to 5, the tube 5 has two long sides 5a, in particular of planar surface, connected by two short lateral sides 5b of height h, which defines the height h of the tube 5. These short sides 5b can be rounded, and are also called radii of the tube 5.

The height h of the tube 5 also corresponds to the overall thickness of the tube 5. This height h of the tube 5 is for example of the order of 1.2mm to 3mm.

In addition, during the process of manufacturing the tube 5, the strip of material 11 forming the tube 5 is folded on itself, so as to define at least one fold 13 in material continuity.

This strip of material 11 is folded on itself at least at one side of the tube 5, also called the nose of the tube 5. It is a small lateral side 5b of the tube 5 intended to be arranged on the side front A of the heat exchanger 1. The side 5b of the tube 5 having one or more folds 13 is configured to extend along a transverse axis, in the width direction, of a motor vehicle equipped with a heat exchanger 1 comprising such a tube 5.

Furthermore, the or each ply 13 is formed by two strip portions 13a, 13b in continuity of material via a return 13c. By "in continuity of material" is meant the fact that the fold 13 is not formed by two disjointed walls secured to each other.

Each fold 13 thus achieves a double strip thickness. In the example of Figures 2 to 4, only a fold 13 is shown. In the example of FIG. 5, two folds 13 are shown and share a portion of common strip 13b. Of course, the invention is not limited to one or two folds 13.

In addition, at least one of the strip portions 13a or 13b of the fold 13 is a portion of protective strip, that is to say ensuring the protection of the tube 5, in particular in the event of an impact of an element of the outdoor environment with tube 5.

At least the portion of protective strip 13a and / or 13b of the fold 13 is formed along the nose or side 5b of the tube 5.

At least the portion of protective strip 13a and / or 13b is produced in an intermediate part 11b of the strip of material 11. The two strip portions 13a and 13b forming a fold 13 can be produced in this intermediate portion 11b of the strip of material 11. As said previously, the intermediate part 11b of the strip of material 11 does not include the lateral ends of the strip of material 11 and neither does it include a junction zone Z of the end portions 11a ( see Figure 4) for the connection of the strip of material 11. The protective fold 13 is therefore not produced at the end parts 11a, or more precisely at the lateral ends.

The strip portions 13a, 13b of each ply 13 can be attached to one another or not.

Provision may be made to braze these strip portions 13a, 13b together at each ply 13, so as to increase the mechanical resistance of the tube 5. The ply (s) 13 being produced in continuity of material, such a brazing step n does not have the effect of sealing the tube 5.

First solution

According to a first solution, various embodiments of which are illustrated diagrammatically in FIGS. 2 to 4, the strip of material 11 is folded so as to form a protuberance 15 or spur. This protrusion 15 extends from the tube 5, more precisely from the side or nose of the tube 5, towards the outside of the tube 5. In other words, this protrusion 15 extends towards the opposite of the circulation channel 9 of the fluid refrigerant delimited by the tube 5.

In other words, the protrusion 15 is formed by the strip portions 13a, 13b of the ply (s) 13. In this case the strip portions 13a, 13b of each ply 13 can be backed up and are advantageously brazed one by one. the other. Of course, more than one fold 13 can be provided.

This protuberance 15 formed from at least two portions of strip 13a, 13b of a fold 13 therefore has a thickness E equal to at least twice the thickness of material of the strip of material 11 forming the tube 5.

In addition, the protuberance 15 can extend over a width L15 (referenced in FIG. 2), advantageously between two and ten times the material thickness of the strip of material 11 forming the tube 5.

Furthermore, the orientation of the pleat (s) 13 forming the protuberance 15 can be adapted as required, as illustrated in the examples of FIGS. 2 to 4.

Referring now to Figure 2 which shows a sectional view of such a tube 5 according to a first embodiment. According to this first example, the fold 13 is formed horizontally in the figure. In this case, the protuberance 15, and therefore the strip portions 13a, 13b forming it, extend parallel to the long sides 5a of the tube 5. This protrusion 15 extends in the transverse direction of the tube 5.

The strip of material 11 forming the tube 5 is therefore folded one or more times on itself horizontally (in the figure) at least at the level of the small lateral side 5b or nose of the tube 5 increasing the dimension of the tube 5, in the direction of the width or transverse of the tube 5.

In this first example, the two strip portions 13a and 13b of the fold 13 forming the protuberance 15 provide the protective function in the event of an impact from an external element such as a gravel.

In the first example of FIG. 2, the tube 5 is only partially shown, of course, the cross section of this tube 5 can be oblong or for example at "B" as described above.

As an alternative, the protuberance 15 can form, with the general plane of extension of the tube 5, corresponding in the figures to a horizontal plane, a non-zero angle. Such an alternative is illustrated in a second exemplary embodiment of a tube 5 in FIG. 3 and in a third exemplary embodiment of a tube 5 in FIG. 4. In other words, the protrusion 15 can form an angle a non null with the large faces 5a of the tube 5.

In particular, the angle a can be of the order of or less than 45 °. According to a particular example, the angle a is of the order of 30 °.

The third embodiment of Figure 4 differs from the second embodiment of Figure 3 by the cross section of the tube 5 at "B" instead of the oblong section.

In these examples, at least the first portion of strip 13a forming the fold 13, which is the most external to the tube 5, is intended to be the first surface in contact with an external element impacting the tube 5, and ensures at least the protective function.

Second solution

According to a second solution illustrated schematically in Figure 5, the strip of material 11 is folded in the direction of the height h of the tube 5. Only the differences from the examples of the first solution are described below.

According to this second solution, the tube 5 therefore has one or more vertical folds 13 which form an extra thickness E ’of material at least at the nose of the tube 5 or small lateral side 5b. The vertical folds 13 of the second solution are similar to the folds 13 according to the second and third examples of the first solution forming a protuberance 15 inclined at an angle on the order of 90 ° with the horizontal.

The tube 5 thus formed then has a variable thickness. In other words, the tube 5 has one or more reinforced zones, that is to say having a greater thickness, obtained by folding over itself the strip of material 11. These reinforced zones correspond to the zones of the tube 5 which are the most requested, in particular, the nose of the tube 5.

Similarly to the first solution, at least one of the portions of strips 13a, 13b of the folds 13 forming the additional thickness E ’ensures the protective function of the tube 5 in the event of an impact from an external element such as a gravel. Indeed, this extra thickness E ’also makes it possible to absorb the energy of the gravel in the event of impact.

In the example illustrated in FIG. 5, only two folds 13 with a portion of common strip 13b are shown. Of course, there is no limitation on the number of plies 13. Several pleats 13 can be provided, in particular with an odd total number of strip portions 13a, 13b.

Furthermore, the folds 13 are produced along the entire height b of the tube 5. At a minimum, the portions of strips 13a, 13b of the folds 13 must extend over a height corresponding to the height of the circulation channel 9, that is to say ie the height h of tube 5 minus twice the material thickness e.

Thus, during the process for obtaining such a tube 5, the strip of material 11 can be folded at the level of at least one intermediate part 11b, as described according to one or other of the variants with reference to FIGS. 2 to 5, so as to form in continuity of material at least one fold 13 formed by two portions of strip 13a, 13b and of which at least one portion of strip 13a and / or 13b forms the protection of the tube 5.

This folding at the level of at least one intermediate portion 11b of the strip of material 11 can be done before the folding of the strip of material 11 in order to obtain a bent tube of oblong cross section or in "B", or any other form . We can then secure the assembly during brazing of the heat exchanger 1.

As a variant, the strip of material 11 is folded back at at least one intermediate portion 11b to form one or more folds 13 can be done before or after electrofusion to form the tube 5.

It is therefore understood that with the fold (s) 13 formed at least at the level of the nose of the tube 5 according to one or other of the embodiments described above, sufficient material is guaranteed to strategic levels so as to withstand forces, in particular from outside, stressing the tube 5.

Of course, other arrangements of the tube 5 making it possible to withstand internal stresses, in particular of the fluid, can be combined with these various embodiments previously described.

Such tubes 5 can be provided in any type of heat exchanger 1, in particular brazed, such as an engine cooling radiator or even a low temperature radiator, or a condenser of an air conditioning loop. The invention can also be applied to a front face or front face module integrating one or more thermals comprising such tubes 5.

Claims (10)

1. Tube (5) of heat exchanger (1) produced from a strip of material (11), the strip of material (11) having two end portions (11a) connected so as to form the tube ( 5), characterized in that the strip of material (11) forming the tube (5) is folded on itself, so as to define at least one fold (13) formed by two portions of strip (13a, 13b) in continuity of material, such as at least a portion of strip (13a, 13b) of the fold (13): - is a portion of protective strip (13a, 13b) of the tube (5) in the event of impact from a element external to the tube (5), and - is produced in an intermediate part (11b) of the strip of material (11). 2. Tube (5) according to the preceding claim, in which the intermediate part (11b) is devoid of a junction zone (Z) between the two end parts (11a) to close the tube (5) in a leaktight manner. . 3. Tube (5) according to one of the preceding claims, wherein said at least one fold (13) is formed along at least one lateral side of the tube (5). 4. Tube (5) according to any one of claims 1 to 3, wherein the strip of material (11) is folded so as to form a projection (15) extending from the tube (5) outward of the tube (5). 5. Tube (5) according to the preceding claim, wherein the projection (15) has a thickness (E) at least equal to twice the material thickness (e) of the material strip (11). 6. Tube (5) according to one of claims 4 or 5, wherein the protrusion (15) forms with the general plane of extension of the tube (5) a non-zero angle (a), in particular less than or 'around 45 °, preferably around 30 °. 7. Tube (5) according to one of claims 4 to 6, in which the protrusion (15) extends over a width (L15) equal to at least twice and at most ten times the material thickness (e ) of the material strip (11). 8. Tube (5) according to any one of claims 1 to 3, in which the strip of material (11) is folded in the height direction (h) of the tube (5), so as to form an additional thickness ( E ') of matter. 9. Tube (5) according to the preceding claim, wherein the height of the strip portions (13a, 13b) of said at least one ply (13) is of the order of the height (h) of the tube (5). 10. Heat exchanger, in particular for a motor vehicle, characterized in that it comprises a bundle of tubes (5) according to any one of the preceding claims.