FR3066015B1 - HEAT EXCHANGER TUBE AND THERMAL HEAT EXCHANGER - Google Patents

Abstract

The heat exchanger tube (5) (1) is produced from a strip of material (11), the strip of material (11) having two end portions connected so as 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 portions of strip (13a, 13b) in continuity of material. At least one 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 an impact from an element external to the tube (5), and is produced in an intermediate part (11b) of the strip of material (11).

Description

The invention relates to a heat exchanger tube, particularly 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, especially 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 face, also called front panel, is a structural element capable of integrating various equipment of the vehicle, such as projectors, turn signals, buzzer, heat exchangers, fan motor unit or cooling module. The heat exchanger is for example used for cooling the engine or for the air conditioning of the passenger compartment. Generally, the heat exchangers conventionally comprise a bundle of tubes and collector boxes into which the ends of the bundle tubes open, so as to allow the circulation of a fluid, especially a cooling fluid, in the tubes of the bundle.

The tubes of such exchangers can be made for example by extrusion. However, this type of manufacturing generates a significant cost, especially because of the need for specific channels for each type of tubes.

Alternatively, the tubes are made from a web of material, for example, by folding the web of material.

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

To protect these heat exchangers, a grid, usually plastic, can be integrated on the front to stop the chippings. However, the integration of such a grid at the front face generates a certain cost.

It is useful to ensure sufficient material resistance at the tube, to avoid any risk of fluid leakage from the heat exchanger for example in case of impact with a grit on the road.

A known solution is to allow the tube to withstand such an impact by locally increasing the thickness of the tube wall 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 folding.

In a first known tube made from a strip of material, the end portions 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 chippings.

Thus, an object of the invention is to propose a solution for a pipe made from a strip of material, providing the tube with improved resistance to external stresses in a simple manner, by at least partially solving the aforementioned drawbacks of the prior art. To this end, the subject of the invention is a heat exchanger tube made from a strip of material, the strip of material having two end portions connected 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 strip portions in continuity of material, such that at least one band portion of the fold: - Is a protective strip portion of the tube in case of impact of an element outside the tube, and - is performed in an intermediate portion of the material strip.

The two portions of strips of said at least one fold can be made in the intermediate portion of the web of material.

In other words, the intermediate portion of the web of material is by definition distinct, i.e., does not include, the lateral ends of the web of material.

The end portions of the web of material each include a lateral end of the web of material.

For example, it is possible to define the intermediate portion of the material strip as the central portion corresponding to 80% of the width of the strip of material, the end portions corresponding for example to the parts having a width of 10% on each side of the strip of material. the intermediate part.

However this value of 80% is purely indicative. What matters is that the intermediate portion does not include the lateral ends of the material web.

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

Thus, advantageously in places of strong stress, especially external to the tube, one creates with the aid of this or these folds, one or more reinforcing zones of the tube for absorbing energy in case of impact of an element. from the outside environment, such as a gravel.

The ply or plies are not made at a connection area or overlapping 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, also achieved for example by soldering or electrofusion, would remain assured. The invention thus has the advantage of protecting the junction between the end portions of the strip of material, and therefore the tightness of the tube.

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

Preferably, the intermediate portion does not include a junction area between the two end portions to seal the tube. In other words, the intermediate portion is devoid of such a junction area.

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 facing an inlet of an external air flow on the front face of a motor vehicle.

According to an exemplary embodiment, the tube has two long 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 more are brazed together so as to increase the mechanical strength of the tube.

The band portions of said at least one fold may be leaned or not to each other.

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

Such an outgrowth is the first surface of the tube with which, for example, a grit comes into contact in the event of impact. The outgrowth 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 made in a simple manner without requiring several manufacturing steps. The protrusion may have a thickness of at least twice the material thickness of the material web.

For example, the protrusion 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 protrusion may extend over a width equal to at least two times and at most ten times the material thickness of the material web.

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 allowance is obtained, advantageously provided at the tube nose, to ensure the mechanical strength and thus protect the tube in case of impacts from the external environment, without risk of leakage of fluid.

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

According to one or the other embodiment, the tube is a folded tube. The tube may have a substantially "B" cross section, defining two parallel channels of fluid circulation delimited by a partition.

The tube may be an electrowelded tube. The invention also relates to a heat exchanger, particularly for a motor vehicle, characterized in that it comprises a bundle of tubes as defined above. Other features and advantages of the invention will emerge more clearly on reading the following description, given by way of illustrative and non-limiting example, and the appended drawings in which: FIG. 1 partially and schematically represents a FIG. 2 is a cross-sectional view partially showing a first example of a tube of the exchanger of FIG. 1; FIG. 3 is a cross-sectional view of a second example of a tube of the exchanger; FIG. FIG. 4 is a cross-sectional view of a third example of a tube of the exchanger of FIG. 1, and FIG. 5 is a cross-sectional view of a fourth example of a tube of FIG. the exchanger of FIG.

In these figures, the identical elements 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 to a single embodiment. Simple features of different embodiments may 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 close but not identical elements. This indexing does not imply a priority of one element 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 an order in time either.

FIG. 1 shows diagrammatically an example of heat exchanger 1 according to the invention. This 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 so-called low-temperature radiators for example for auxiliary cooling circuits in the motor vehicle. It may also be for example a condenser of an air conditioning loop. The heat exchanger 1, such as a cooling radiator, placed on the front 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 radiator grille of the motor vehicle, or 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 front / rear terms are designated with reference to the forward direction of the motor vehicle to be equipped with a heat exchanger 1 as described. Similarly, the terms vertical / horizontal are designated with reference to the arrangement of the elements in Figures 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. When mounted in the motor vehicle, the heat exchanger 1 can be arranged to allow for example a transverse flow of fluid in the tubes 5 which extend transversely to the motor vehicle. However, there are configurations in which the circulation is vertical 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 brazed by passing through a brazing furnace, to ensure the joining of all components. Note that other plastic elements in particular are typically reported on after soldering, such as water boxes.

The tubes 5 (FIGS. 2 to 5) may extend longitudinally along a length l-5 diagrammatically in FIG. 1. The ends of these tubes 5 open into the collecting boxes 7, for example by means of collecting plates (not shown). which can be arranged transversely with respect to the tubes 5.

Each tube 5 delimits 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 inner interlayer, for example corrugated, can be inserted into the or each circulation channel 9. This inner interlayer has for example a thickness of the order of 80pm to 140pm. The invention relates more specifically 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 made from a strip of material 11. It is in particular a metal strip 11. The metal strip is preferably aluminum or 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 thereafter material thickness. This material thickness e is constant. By way of example, the material thickness e can be of the order of 180 μm to 270 μm, in particular of the order of 200 μm to 270 μm.

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

In particular, the material strip 11 has end portions 11a, visible in the example of Figure 4, which are connected to form the tube 5, in particular for sealing the tube 5. These end portions 11a comprise the lateral ends or lateral edges of the material strip 11. The sealing can be provided by soldering at the junction of the end portions 11a. Alternatively, it may be an electrowelded tube.

The material web 11 also has an intermediate portion 11b. This intermediate portion 11b does not include the lateral ends of the material web 11. The intermediate portion 11b is distinct from the end portions 11a. By way of nonlimiting example, the end portions 11a of the strip of material 11 can 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. material band 11.

The intermediate portion 11b in turn forms a central portion extending for example over a width of about 80% of the total width of the strip of material 11.

Moreover, the end portions 11a and the intermediate portion 11b each have a longitudinal extension corresponding to the longitudinal extension of the tube 5.

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

Alternatively, the tube 5 may be bent or shaped to define or at least two circulation channels 9 (Figure 4). The tube 5 may have a cross section called "B".

The "B" cross section of the illustrated tube 5 has two parallel fluid circulation channels juxtaposed 9 and separated by a spacer wall. For this purpose, the metal strip is folded so as to form the envelope of these parallel circulation channels 9 juxtaposed. The partition is made jointly by the opposite end portions 11a folded 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, circled in dotted line on the Figure 4, the two end portions 11a to form the partition.

A "B" folded tube has been described here. Of course, any other type of folding can be provided.

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

According to one or other of the variants shown in Figures 2 to 5, the tube 5 has two long sides 5a, in particular of flat surface, connected by two small sides 5b lateral height h, which defines the height h of the tube 5. These small sides 5b can be rounded, and are also called spokes 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 tube 5 is for example of the order of 1.2 mm to 3 mm.

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

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 before A of the heat exchanger 1. The side 5b of the tube 5 having one or more plies 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.

Moreover, the or each fold 13 is formed by two strip portions 13a, 13b in continuity of material via a return 13c. The term "continuity of material" means that the fold 13 is not formed by two disjoint walls secured to each other.

Each fold 13 thus produces a double strip thickness. In the example of Figures 2 to 4, only one fold 13 is shown. In the example of Figure 5, two folds 13 are shown and share a common band portion 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 protective strip portion, that is to say ensuring the protection of the tube 5, in particular in the event of impact of an element of the external environment with the tube 5.

At least the portion of the 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 band portion 13a and / or 13b of protection is made in an intermediate portion 11b of the strip of material 11. The two strip portions 13a and 13b forming a fold 13 can be made in this intermediate portion 11b of the strip 11. As previously mentioned, the intermediate portion 11b of the material web 11 does not include the lateral ends of the material web 11 and does not include a zone of junction Z of the end portions 11a ( see Figure 4) for the connection of the material web 11. The fold 13 of protection is not made at the end portions 11a, or more precisely at the lateral ends.

The strip portions 13a, 13b of each fold 13 may be leaning against each other or not.

It can be provided to braze these strip portions 13a, 13b together at each fold 13, so as to increase the strength of the tube 5. The or folds 13 being made in continuity of material, such a soldering 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 material strip 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 belt portions 13a, 13b of the fold or folds 13. In this case the strip portions 13a, 13b of each fold 13 can be backed and are advantageously brazed one to the other. Of course, more than one fold 13 can be provided.

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

In addition, the protrusion 15 may 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.

Moreover, the orientation of the fold or folds 13 forming the protrusion 15 may 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 protrusion 15, and therefore the band 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 thus folded one or more times on itself horizontally (in the figure) at least at the small lateral side 5b or nose of the tube 5 increasing the dimension of the tube 5, in the direction 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 protrusion 15 provide the protection function in case of impact of an external element such as a grit.

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

Alternatively, the protrusion 15 may 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 on a second exemplary embodiment of a tube 5 of FIG. 3 and on a third embodiment of a tube 5 of FIG. 4. In other words, the protrusion 15 can form an angle α. Nil with the large faces 5a of the tube 5.

In particular, the angle α may be of the order of or less than 45 °. In 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 band portion 13a forming the fold 13, which is the outermost tube 5, is intended to be the first surface in contact with an outer member impacting the tube 5, and ensures at least the protection function.

Second solution

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

According to this second solution, the tube 5 thus 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 protrusion inclined at an angle of 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 areas, that is to say zones having a greater thickness, obtained by folding on itself of the material strip 11. These reinforced zones correspond to the zones of the tube 5 which are the most stressed, in particular, the nose of the tube 5.

Similarly to the first solution, at least one of the strip portions 13a, 13b of the folds 13 forming the extra thickness E 'ensures the protective function of the tube 5 in case of impact of an external element such as a grit. Indeed, this extra thickness E 'also allows to absorb the energy of the gravel in case of impact.

In the example shown in Figure 5, only two folds 13 with a common band portion 13b are shown. Of course, there is no limitation on the number of plies 13. It is possible to provide several plies 13, in particular with an odd total number of strip portions 13a, 13b.

Furthermore, the folds 13 are made along the entire height of the tube 5. At least the strip portions 13a, 13b of the folds 13 must extend over a height corresponding to the height of the circulation channel 9, c ' that is, the height h of tube 5 minus twice the material thickness e.

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

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

Alternatively, the folding of the strip of material 11 at the level of at least one intermediate portion 11b to form one or more plies 13 can be done before or after electrofusion to form the tube 5.

It is therefore understood that with the (s) fold (s) 13 formed (s) at least at the nose of the tube 5 according to one or other of the previously described embodiments, sufficient material is guaranteed to strategic levels so as to withstand forces, including external forces, soliciting the tube 5.

Of course, other arrangements of the tube 5 to withstand internal stresses, including fluid, can be combined with these various embodiments described above.

Such tubes 5 may be provided in any type of heat exchanger 1, in particular brazed, such as an engine cooling radiator or 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 (4)

1. Tube (5) of heat exchanger (1) made from a strip of material (11), the strip of material (11) having two end portions (11a) connected 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 that 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 external to the tube (5), and - is made in an intermediate portion (11b) of the strip of material (11) devoid of a junction zone (Z) between the two end portions (11a) for closing the tube (5) sealingly. 2. Tube (5) according to the preceding claim, wherein said at least one fold (13) is formed along at least one lateral side of the tube (5). A tube (5) as claimed in any one of the preceding claims, wherein the strip of material (11) is folded to form an outgrowth (15) extending from the tube (5) to the outside of the tube (5). 4. Tube (5) according to the preceding claim, wherein the protrusion (15) has a thickness (E) at least equal to twice the material thickness (e) of the material web (11). 5. Tube (5) according to one of claims 3 or 4, wherein the protrusion (15) forms with the general plane of extension of the tube (5) an angle (a) non-zero, especially lower or order of 45 °, preferably of the order of 30 °. 6. Tube (5) according to one of claims 3 to 5, wherein 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 web (11). 7. Tube (5) according to any one of claims 1 and 2, wherein the strip of material (11) is folded in the direction of the height (h) of the tube (5), so as to form an extra thickness ( E ') of matter. 8. Tube (5) according to the preceding claim, wherein the height of the strip portions (13a, 13b) of said at least one fold (13) is of the order of the height (/?) Of the tube (5). 9. Heat exchanger, especially for a motor vehicle, characterized in that it comprises a tube bundle (5) according to any one of the preceding claims.