FR3066014A1 - HEAT EXCHANGER WITH PROTECTION DEVICE AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

The present invention relates to a heat exchanger (1) comprising a bundle of flat tubes (2), said bundle of flat tubes (2) comprising: a multitude of flat tubes (2) arranged parallel to one another and in a row, said flat tubes (2) having two large planar and parallel sides (21) and two short sides connecting the ends of said long sides (21), said small sides forming the slices (22) of the flat tubes (2), a plurality of spacers (6) arranged and brazed between the long sides (21) of the flat tubes (2), the spacers (6) having a corrugated profile and protruding from at least one of the slices (22) over the width (N) of the flat tubes (2), the corrugations (60) comprising: • a first central profile at the long sides (21) of the flat tubes (2), and • a second peripheral profile at at least one of the slices (22). ) flat tubes (2) at least partially covering said slice (22) on r the height (H) of the flat tubes (2).

Description

The invention relates to the field of heat exchangers and more particularly the heat exchangers placed on the front face of a motor vehicle. The invention also relates to the process for manufacturing such a heat exchanger.

In the automotive field, the heat exchangers placed on the front face generally comprise flat tubes, inside which circulates a heat transfer fluid, and spacers disposed and brazed between the flat tubes. These heat exchangers can undergo projections of debris or stones which can damage or even pierce the flat tubes.

In order to protect these heat exchangers and in particular the flat tubes, it is known to place a protective device in front of the latter which can absorb these shocks. However, fixing these protective devices generally requires a dedicated step during the manufacture of these heat exchangers, which increases production times and costs.

In order to limit the costs and not to increase the manufacturing time, a known solution is to have spacers between the flat tubes of width greater than the width of the flat tubes so that the spacers protrude from the flat tubes. So if debris or stones arrive at the heat exchanger, the spacers are affected and the flat tubes are preserved. It is also known that the spacers also cover at least partially the side of the flat tube to reinforce the protection.

However, in order to form such spacers, they are deformed and at this deformation, the thickness of the interlayer is reduced which can lead to brittleness and potential cracks.

Thus, one of the aims of the invention is to at least partially remedy the drawbacks of the prior art and to propose an improved heat exchanger and its manufacturing process.

The present invention therefore relates to a heat exchanger comprising a bundle of flat tubes, said bundle of flat tubes comprising: ° a multitude of flat tubes in which a first heat transfer fluid is intended to circulate and arranged parallel to each other and in a row, said flat tubes comprising two long flat and parallel sides and two short sides connecting the ends of said long sides, said short sides forming the edges of the flat tubes, ° a plurality of tabs arranged and brazed between the long sides of the flat tubes and between which a second heat transfer fluid is intended to circulate, the spacers having a corrugated profile and projecting at least one of the edges over the width of the flat tubes, the corrugations comprising: • a first central profile at the long sides of the flat tubes in which the top of the corrugations has a flat surface in longitudinal section coming into contact with said long sides, and • a second peripheral profile at the level of at least one of the sections of the flat tubes in which the tops of the corrugations have in longitudinal section a curvature at least partially covering said section on the height of the flat tubes.

According to another aspect of the invention, the development of the spacers between the first central profile, the second peripheral profile and the transition zone between said profiles has a difference in elongation of between 0 and 5%, preferably less than 1% .

According to another aspect of the invention, over the width of the flat tubes, the spacers follow the shape of said flat tubes and their edges.

According to another aspect of the invention, the edges of the flat tubes have a rounded shape.

According to another aspect of the invention, only the tops of the corrugations having a flat surface are brazed on the flat tubes.

According to another aspect of the invention, the thickness of the spacers is between 50 μm and 120 μm.

According to another aspect of the invention, the difference between two curved vertices of two spacers covering a slice is between 0.1 mm and 1 mm.

According to another aspect of the invention, the distance from which the inserts pass beyond the edges of the flat tubes is between 1 mm and 5 mm.

According to another aspect of the invention, the edges of the flat tubes on one and the same side of the bundle are covered.

According to another aspect of the invention, the edges of the flat tubes on both sides of the bundle are covered.

According to another aspect of the invention, the tubes have a wall thickness greater than or equal to 230 μm, for example greater than or equal to 250 μm, for example still greater than or equal to 270 μm.

The present invention also relates to a method of manufacturing a heat exchanger comprising a bundle of flat tubes, said bundle of flat tubes comprising: ° a multitude of flat tubes in which a first heat transfer fluid is intended to circulate and arranged in parallel to the others and in a row, said flat tubes comprising two large flat and parallel sides and two short sides connecting the ends of said long sides, said short sides forming the edges of the flat tubes, ° a plurality of spacers disposed and brazed between the large sides flat tubes between which a second heat transfer fluid is intended to circulate, the spacers having a corrugated profile and projecting at least one of the edges of the flat tubes, the method comprising a step of manufacturing the corrugated spacers and whose width is greater than the width of the flat tubes so as to protrude at least ins one side of said flat tubes once mounted, said spacers comprising two profiles distinct from the tops of their undulations: ° a first central profile in which the top of the undulations has in longitudinal section a flat surface intended to come against the long side of the flat tube , and ° a second peripheral profile in which the top of the corrugations has in longitudinal section a curved profile intended to cover at least partially a wafer over the height of the flat tube.

According to one aspect of the method according to the invention, the manufacture of the spacers is carried out by passing metal strips between at least two shaping wheels which deform said strips according to the desired pattern.

According to another aspect of the method according to the invention, said method comprises a brazing step carried out only at the level of the first central profile, between the vertices having a flat surface and the flat tubes.

The present invention also relates to a heat exchanger comprising a bundle of flat tubes, said bundle of flat tubes comprising: a multitude of flat tubes in which a first heat transfer fluid is intended to circulate and arranged parallel to one another and in row, said flat tubes comprising two long flat and parallel sides and two short sides connecting the ends of said long sides, said short sides forming the edges of the flat tubes, ° a plurality of tabs arranged and brazed between the long sides of the flat tubes and between which a second heat transfer fluid is intended to circulate, the spacers having a corrugated profile and protruding at least one of the sections over the width of the flat tubes, the corrugations comprising: a first central profile in longitudinal section at the long sides of the flat tubes , and a second peripheral profile in longitudinal section e at the level of at least one of the sections of the flat tubes covering at least partially said section over the height of the flat tubes, the development of the spacers between the first central profile, the second peripheral profile and the transition zone between said profiles having a difference in elongation between 0 and 5%, preferably less than 1%.

The present invention also relates to a method of manufacturing a heat exchanger comprising a bundle of flat tubes, said bundle of flat tubes comprising: ° a multitude of flat tubes in which a first heat transfer fluid is intended to circulate and arranged in parallel to the others and in a row, said flat tubes comprising two large flat and parallel sides and two short sides connecting the ends of said long sides, said short sides forming the edges of the flat tubes, ° a plurality of spacers disposed and brazed between the large sides tubes between which a second heat transfer fluid is intended to circulate, the spacers having a corrugated profile and protruding by at least one of the sections of the flat tubes, the method comprises a step of manufacturing the corrugated spacers and whose width is greater than the width of the flat tubes so as to exceed at least one c removed from said flat tubes once mounted, said spacers comprising two profiles distinct from the tops of their undulations: a first central profile in longitudinal section at the long sides of the flat tubes, and a second peripheral profile in longitudinal section at at least one of the edges of the flat tubes covering at least partially said edge over the height of the flat tubes, the developed spacers between the first central profile, the second peripheral profile and the transition zone between said profiles having a difference in elongation between 0 and 5%, preferably less than 1%. 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 shows a schematic perspective representation of 'a heat exchanger, • Figure 2 shows a schematic sectional representation of a flat tube, • Figure 3 shows a schematic representation in side view of the connection between spacers and a flat tube, • Figure 4 shows a schematic representation of the connection between spacers and a flat tube of Figure 2 along the section plane II.

In the various figures, identical elements have the same reference numbers.

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 only to a single embodiment. Simple features of different embodiments can also be combined and / 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 even first criterion and second criterion etc. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are similar but not identical. This indexing does not imply a priority of an element, parameter or criterion 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 for example to assess this or that criterion.

FIG. 1 shows a heat exchanger 1, generally of rectangular shape, comprising a bundle formed by a multitude of flat tubes 2 inside which a first heat transfer fluid can circulate between the two ends of the flat tubes 2. The flat tubes 2 are arranged parallel to each other and in a row.

Between the tubes 2, are placed spacers 6 which act as a disturbance and increase the heat exchange surface with a second heat transfer fluid passing between the tubes 2.

The tubes 2 and the spacers 6 are made of metal, for example aluminum or aluminum alloy, and brazed to each other. The spacers 6 are for example strips or corrugated plates and placed between the tubes 2 and fixed to said tubes 2 by brazing.

In the context of a heat exchanger 1 arranged on the front face of a motor vehicle, the first heat transfer fluid may for example be glycol water for a radiator of an engine cooling circuit or else a refrigerant fluid for a air conditioning circuit condenser. The second heat transfer fluid can be outside air. The heat exchanger 1 also comprises two collectors 3 or water boxes, a collector 3 being disposed at each end of the tubes 2. These collectors 3 each comprise a collecting plate 4 and a cover 8 which covers the collecting plate 4 and close the collector 3. These collectors 3 allow the collection and / or distribution of the first heat transfer fluid so that it circulates in the tubes 2.

The collector plate 4 makes a sealed connection between the manifold 3 and the bundle of tubes 2. In addition, the collector plate 4 can be of generally rectangular shape. The collecting plate 4 also includes a multitude of orifices (not shown) having a shape corresponding to the shape of the section of the tubes 2 and suitable for receiving the ends of the tubes 2. The tubes 2 are fixed to the collecting plate 4 so waterproof.

As shown in FIG. 2, the flat tubes 2 are of oblong section and include two long sides 21 planes and parallel and two short sides connecting the ends of said long sides 21. The short sides of the flat tubes form the edges 22 of flat tubes 2. The edges 22 can in particular be rounded as illustrated in FIG. 2, however it is entirely possible to imagine other edge profiles 22 such as, for example, flat or tapered. In the present description, the height H of the flat tubes 2 is understood to mean the distance between the external surfaces of their two large ribs 21. The width N of the flat tubes 2 corresponds to the distance between the external surfaces of the two sections 22 flat tubes 2. The length L of the flat tubes 2 (visible in FIG. 1) corresponds to the distance between the two ends of the flat tubes 2.

In the present description, it will then be possible to speak of a longitudinal axis or of a longitudinal section as a function of the axis of the length L of the flat tubes 2.

As illustrated in FIG. 3, the spacers 6 have periodic undulations 60 along the longitudinal axis of the flat tubes. These corrugations 60 have for example a half-period P of between 1 and 1.5 mm. The spacers 6 are more particularly plates or bands folded in an accordion fashion in order to form corrugations 60 and placed so that the vertices 61, 62 of the corrugations 60 are arranged against a long side 21 of a flat tube 2. The corrugations 60 comprise more particularly vertices 61,62 and flanks 63 connecting the vertices 61,62. The inserts 6 may also have on their sides 63 edges or openings 64 (visible in FIG. 3), perpendicular or oblique with respect to the direction of circulation of the second heat transfer fluid within the inserts 6. These edges or openings 64 are in particular suitable deflecting and disturbing the circulation of the second heat transfer fluid in order to promote heat transfer between the second heat transfer fluid passing through the spacers and the first heat transfer fluid passing through the flat tubes 2.

In order to protect the sections 22 of the tubes 2 for projecting debris or stones, in particular in the context of front face heat exchangers 1, the spacers 6 protrude from said sections 22 over the width N of the flat tubes 2, as illustrated in Figure 4. The distance D of the spacers 6 beyond the edges 22 of the flat tubes 2 may in particular be between 1 mm and 5 mm.

In addition, the spacers 6 at least partially cover one of the sections 22 of the flat tubes 2 over their height H. This makes it possible to increase the protection of the tubes 2 against debris and stones which may reach them.

The inserts 6 may protrude from the flat tubes 2 over their width N and at least partially cover the edges 22 of the said flat tubes 2 over their height H on both sides of the bundle. Thus, the spacers 6 are symmetrical and easy to install between the flat tubes 2. Here, the side of the bundle is understood to mean the sides by which the second heat transfer fluid enters and leaves. Conversely, the spacers 6 can protrude from the flat tubes 2 over their width N and at least partially cover the edges 22 of the said flat tubes 2 over their height H with one and the same side of the bundle, more particularly on the side of the bundle and of the heat exchanger 1 most likely to receive debris and stones. Thus the spacers 6 are asymmetrical and the increases in material and weight of the heat exchanger 1 are limited.

The spacers 6 more particularly comprise two distinct profiles of their corrugations 60 depending on whether they face the long sides 21 or the edges 22 of the flat tubes 2.

A first so-called central profile is disposed at the long sides 21 of the flat tubes 2. For this first central profile, the apex 61 of the corrugations 60 has in longitudinal section a flat surface coming against a large side 21 of the flat tube 2. This surface flat allows good brazing between the interlayer 6 and the flat tube 2. In addition, this increases the contact surface and therefore the heat transfer between the flat tube 2 and the interlayer 6.

A second so-called peripheral profile is disposed at the level of the covered sections 22. For this second peripheral profile, the apex 62 of the corrugations 60 has in longitudinal section a curved profile covering at least partially said edge 22.

By longitudinal section is meant here that the profiles of the vertices 61, 62 of the undulations 60 are observed perpendicular to the longitudinal axis of the beam, as shown in FIG. 3.

More specifically, the development of the dividers 6 between the first central profile, the second peripheral profile and the transition zone between said profiles has an elongation difference of between 0 and 5%, preferably less than 1%.

By developed (or developed length) is meant the length of the strip with the neutral fiber (generally at mid-material thickness). Having an identical or close development between these three zones consists in not creating different elongations or with a very small difference in elongation for these zones.

The fact of presenting these two distinct profiles of vertices at the level of the long sides 21 and of the overlapped sections 22, makes it possible to avoid stretching and too great a thinning of the interlayer 6 at the level of the transition between its two profiles. Thus the tab 6 keeps a relatively constant thickness, for example between 50 μm and 120 μm, and reduces the risks of embrittlement or of formation of cracks at this transition.

The spacers 6 can thus follow the shape of the flat tubes 2 and their edges 22, as illustrated in FIG. 4, in order to facilitate mounting as well as brazing.

The brazing between the spacers 6 and the flat tubes 2 can, for example, be carried out only at the level of the vertices 61 having a flat surface. This allows in particular in the event of a shock a deformation of the tab 6 without the deformation forces being transmitted to the edge 22 and to the flat tube 2.

According to another embodiment, the brazing between the spacers 6 and the flat tubes 2 can be carried out at the vertices 61 having a flat surface as well as at the curved vertices 62. The spacers 6 are then brazed on the long sides 21 as well as on the edges 22 of the flat tubes. This allows in particular a good fixing of the spacers 6 but also increases the contact and heat exchange surface.

As shown in FIG. 3, the difference E between two curved vertices 62 of two inserts 6 covering a slice 22 can be between 0.1mm and 1mm. The vertices 61, 62 of the undulations 60 of the spacers located on either side of a flat tube 2 can face each other, as illustrated in FIG. 2. However, it is entirely possible to imagine that the vertices 61 , 62 of the corrugations 60 of the spacers located on either side of a flat tube 2 are offset with respect to each other.

The present invention also relates to the method for manufacturing the heat exchanger 1 as described above. This manufacturing process includes in particular a step of manufacturing corrugated dividers 6 whose width is greater than the width N of the flat tubes 2 so as to protrude at least one side of said flat tubes 2 once mounted. These inserts 6 comprise two distinct profiles of the vertices 61, 62 of their corrugations 60: • a first central profile in which the vertex 61 of the corrugations 60 has a flat surface intended to come against the long side 21 of the flat tube 2, and • a second peripheral profile in which the apex 62 of the corrugations 60 has a curved profile intended to at least partially cover a slice 22 over the height H of the flat tube 2.

During this step of manufacturing the spacers 6, the development between the first central profile, the second peripheral profile and the transition zone between said profiles has an elongation difference of between 0 and 5%, preferably less than 1%.

These undulations 60 and these two distinct profiles are produced in particular by passing a strip between at least two shaping wheels which deform the strip according to the desired pattern.

The fact of creating these two distinct profiles directly during the manufacture of interlayer 6 and by means of shaping wheels makes it possible to avoid stretching and too great thinning of interlayer 6 at the transition between its two profiles. The deformation forces when passing between the shaping wheels are identical for the two separate profiles. Thus, the thickness of the interlayer 6 is as constant as possible.

The inserts 6 can have a second profile on each side so that, once mounted on the flat tubes 2, said inserts 6 protrude and cover the two sections 22 of said flat tubes 2. Conversely, inserts 6 can have a second profile on one side only so that, once mounted on the flat tubes 2, said spacers 6 protrude and cover a single edge 22 of said flat tubes 2. In this case, the spacers 6 are arranged on the flat tubes so that the edges 22 of the covered flat tubes 2 are on the same side of the heat exchanger 1.

The manufacturing process also includes a step of brazing the spacers 6 on the flat tubes 2. This brazing step can be carried out only at the level of the first central profile or else at the level of the first and second profile.

Thus, it can be seen that because of their conformation as well as their manufacturing process, the spacers 6 can keep a constant thickness both at the level of the first profiles in contact with the long sides 21 of the flat tubes 2 as well as of the second profiles at contact of the edges 22 of the flat tubes 2.

Claims (15)

1. Heat exchanger (1) comprising a bundle of flat tubes (2), said bundle of flat tubes (2) comprising: ° a multitude of flat tubes (2) in which a first heat transfer fluid is intended to circulate and arranged in parallel to each other and in a row, said flat tubes (2) comprising two long sides (21) planes and parallel and two short sides connecting the ends of said long sides (21), said short sides forming the edges (22) of the flat tubes (2), ° a plurality of spacers (6) arranged and brazed between the long sides (21) of the flat tubes (2) and between which a second heat transfer fluid is intended to circulate, the spacers (6) having a corrugated profile and protruding by at least one of the sections (22) over the width (N) of the flat tubes (2), characterized in that the corrugations (60) comprise: • a first central profile at the level of the long sides (21) of the flat tubes (2) in which the top and (61) corrugations (60) has in longitudinal section a flat surface coming into contact with said long sides (21), and • a second peripheral profile at the level of at least one of the edges (22) of the flat tubes (2) wherein the tops (62) of the corrugations (60) have in longitudinal section a curvature at least partially covering said edge (22) over the height (H) of the flat tubes (2). 2. Heat exchanger (1) according to the preceding claim, characterized in that the development of the spacers (6) between the first central profile, the second peripheral profile and the transition zone between said profiles has a difference in elongation between 0 and 5%, preferably less than 1%. 3. Heat exchanger (1) according to one of the preceding claims, characterized in that over the width (N) of the flat tubes (2), the spacers (6) follow the shape of said flat tubes (2) and their slices (22). 4. Heat exchanger (1) according to one of the preceding claims, characterized in that the edges (22) of the flat tubes (2) have a rounded shape. 5. Heat exchanger (1) according to one of the preceding claims, characterized in that only the vertices (61) of the corrugations (60) having a flat surface are brazed on the flat tubes (2). 6. Heat exchanger (1) according to one of the preceding claims, characterized in that the thickness of the spacers (6) is between 50 pm and 120 pm. 7. Heat exchanger (1) according to one of the preceding claims, characterized in that the difference (E) between two vertices (62) curves of two spacers (6) covering a wafer (22) is between 0, 1 mm and 1 mm. 8. Heat exchanger (1) according to one of the preceding claims, characterized in that the distance (D) of protrusion of the spacers (6) relative to the edges (22) of the flat tubes (2) is between 1 mm and 5 mm. 9. Heat exchanger (1) according to one of the preceding claims, characterized in that the edges (22) of the flat tubes (2) on one and the same side of the bundle are covered. 10. Heat exchanger (1) according to one of claims 1 to 8, characterized in that the edges (22) of the flat tubes (2) on both sides of the bundle are covered. 11. A method of manufacturing a heat exchanger (1) comprising a bundle of flat tubes (2), said bundle of flat tubes (2) comprising: ° a multitude of flat tubes (2) in which a first heat transfer fluid is intended to circulate and arranged parallel to one another and in a row, said flat tubes (2) having two long sides (21) planes and parallel and two short sides connecting the ends of said long sides (21), said short sides forming the edges (22) flat tubes (2), ° a plurality of spacers (6) disposed and brazed between the long sides (21) of the tubes between which a second heat transfer fluid is intended to circulate, the spacers (6) having a profile corrugated and projecting from at least one of the sections (22) of the flat tubes (2), characterized in that the method comprises a step of manufacturing the corrugated spacers (6) whose width is greater than the width (N) of theflat tubes (2) so as to project at least one side of said flat tubes (2) once mounted, said spacers (6) comprising two distinct profiles of the tops (61,62) of their undulations (60): ° a first central profile in which the top (61) of the corrugations (60) has in longitudinal section a flat surface intended to come against the long side (21) of the flat tube (2), and ° a second peripheral profile in which the top ( 62) corrugations (60) has in longitudinal section a curved profile intended to cover at least partially a wafer (22) over the height (H) of the flat tube (2). 12. The manufacturing method according to claim 11, characterized in that the manufacturing of the spacers (6) is carried out by passing metal strips between at least two shaping wheels which deform said strips according to the desired pattern. 13. The manufacturing method according to one of claims 11 or 12, characterized in that it comprises a brazing step carried out only at the level of the first central profile, between the vertices (61) having a flat surface and the flat tubes ( 2). 14. Heat exchanger (1) comprising a bundle of flat tubes (2), said bundle of flat tubes (2) comprising: ° a multitude of flat tubes (2) in which a first heat transfer fluid is intended to circulate and arranged in parallel to each other and in a row, said flat tubes (2) comprising two long sides (21) planes and parallel and two short sides connecting the ends of said long sides (21), said short sides forming the edges (22) of the flat tubes (2), ° a plurality of spacers (6) arranged and brazed between the long sides (21) of the flat tubes (2) and between which a second heat transfer fluid is intended to circulate, the spacers (6) having a corrugated profile and projecting from at least one of the sections (22) over the width (N) of the flat tubes (2), characterized in that the corrugations (60) comprise: a first central profile in longitudinal section at the level of the long sides (21 ) flat tubes ( 2), and a second peripheral profile in longitudinal section at at least one of the edges (22) of the flat tubes (2) at least partially covering said edge (22) over the height (H) of the flat tubes (2) , the developed spacers (6) between the first central profile, the second peripheral profile and the transition zone between said profiles having a difference in elongation between 0 and 5%, preferably less than 1%. 15. Method for manufacturing a heat exchanger (1) comprising a bundle of flat tubes (2), said bundle of flat tubes (2) comprising: ° a multitude of flat tubes (2) in which a first heat transfer fluid is intended to circulate and arranged parallel to one another and in a row, said flat tubes (2) having two long sides (21) planes and parallel and two short sides connecting the ends of said long sides (21), said short sides forming the edges (22) flat tubes (2), ° a plurality of spacers (6) disposed and brazed between the long sides (21) of the tubes between which a second heat transfer fluid is intended to circulate, the spacers (6) having a profile corrugated and projecting from at least one of the sections (22) of the flat tubes (2), characterized in that the method comprises a step of manufacturing the corrugated spacers (6) whose width is greater than the width (N) of theflat tubes (2) so as to protrude at least one side of said flat tubes (2) once mounted, said spacers (6) comprising two distinct profiles of the tops (61,62) of their corrugations (60): a first central profile in longitudinal section at the long sides (21) of the flat tubes (2), and a second peripheral profile in longitudinal section at the level of at least one of the edges (22) of the flat tubes (2) covering at least partially said edge (22) over the height (H) of the flat tubes (2), the developed spacers (6) between the first central profile, the second peripheral profile and the transition zone between said profiles having a difference in elongation included between 0 and 5%, preferably less than 1%.