EP2334835A1

EP2334835A1 - Heat exchanger with reduced component thickness and method for making same

Info

Publication number: EP2334835A1
Application number: EP09783620A
Authority: EP
Inventors: Yann Pichenot; Alain Bauerheim; Sylvain Henry
Original assignee: Valeo Systemes Thermiques SAS; Alcan Rhenalu SAS
Current assignee: Valeo Systemes Thermiques SAS; Constellium Issoire SAS
Priority date: 2008-10-01
Filing date: 2009-10-01
Publication date: 2011-06-22
Also published as: WO2010037803A1; FR2936597A1

Abstract

The invention relates to a heat exchanger and to a method for making same. The exchanger comprises components essentially made of aluminium (Al). The components include a tube cluster, inserts disposed between and/or in the tubes of said cluster, and at least one collector plate. The method of the invention includes the steps of: selecting tubes made of an aluminium core alloy and comprising 0.3 and 3.0 wt % of magnesium (Mg) as well as other chemical elements; selecting the thickness of said tubes independently from the thickness of said spacers; coating at least one surface of at least some of said components with an aluminium filler alloy; and assembling said components by flux-free brazing in a controlled atmosphere at a temperature of between 580°C and 620°C.

Description

Heat exchanger with reduced component thickness and method of manufacture

The invention relates to a heat exchanger comprising substantially aluminum components, with a bundle of tubes, spacers and at least one collector plate, and to its manufacturing process.

Generally, the heat exchangers conventionally comprise a bundle of tubes and two collector plates which are traversed by the ends of the tubes of the bundle of tubes. Interlayers may be provided between the tubes of said bundle to improve heat exchange. In this case we refer to said spacers generally fins. Interlayers may also be provided in tubes to allow a turbulence generation of the fluid flowing inside said tube, in this case we refer to the spacers generally turbulence generators or "turbulators" or "disruptive".

When an exchanger is in operation, a first fluid circulates inside the tubes of the bundle of tubes, while a second fluid sweeps outside the bundle of tubes. The variations in temperature of the fluid flowing inside the tubes may cause temperature differences that cause thermal expansion between the inlet, outlet and the center of the exchanger. This results in mechanical stresses in the tubes as well as in the collector plates. Such stresses can cause breaks and / or cracks in the exchanger, resulting in risks of leakage of the fluid.

The spacers mentioned above and in particular their thickness must be substantially chosen according to the dimensions and thickness of the tubes so as not to participate actively in mechanical stresses and to support the risk of rupture and / or cracking. Indeed, as detailed below, the mechanical stresses are directly related to the triple synergy tube thickness - heat exchanger model - thickness of interlayer.

Moreover, to limit the manufacturing costs of heat exchangers, today tends more and more towards a relatively thin tube thickness. Consequently, the tubes are less and less resistant to the thermal shocks mentioned above and thus the risks of rupture / crack increase.

It is therefore necessary to reinforce mechanically and / or chemically the materials constituting the components of the heat exchangers.

SUBSTITUTE SHEET (RULE 26) Magnesium is known to strengthen the components of a heat exchanger. However, the use of magnesium deteriorates brazing quality when assembling heat exchanger components. In addition, the use of magnesium is incompatible with so-called flux soldering processes, because of the reactivity between magnesium and the fluorine still present in flux soldering processes.

The invention improves the situation.

The use of this method and of the aforementioned material makes it possible in this case to be able, on heat exchangers of the type of engine cooling radiators and air coolers supercharging, very significantly reduce the thickness of said tubes and said spacers.

For this purpose, the invention proposes a method for manufacturing a heat exchanger comprising essentially aluminum components, said components comprising a bundle of tubes, spacers between and / or in the tubes of said bundle and at least one collector plate . The method of the invention comprises the following steps: to choose tubes consisting of an alloy core based on aluminum and comprising magnesium (Mg) of between 0.3% and 3.0% by weight, and other chemical elements, choosing a thickness of said tubes independently of the thickness of said spacers, coating at least one side of at least some of said components of an aluminum-based filler alloy, and assembling said components by soldering without flux in a controlled atmosphere at a temperature comprised between 58O ⁰ C and 62O ⁰ C followed by cooling (rapid and optionally, a tempering at a temperature between 8O ⁰ C and 250 ⁰ C).

The method makes it possible to obtain a heat exchanger resistant to mechanical stresses. A high magnesium (Mg) content in the tubes gives them a high breaking strength. In addition, the supply of magnesium allows the use of reduced thickness tubes. According to one embodiment of the invention, the core alloy has a composition by weight:

SUBSTITUTE SHEET (RULE 26) Silicon (Si) between 0.5% and 0.7%; Iron (Fe) <1.0%; Copper (Cu) of between 0.3% and 1.0%; Manganese (Mn) from 0.3% to 2.0%; Zinc (Zn) <6.0%; Titanium (Ti) <0.1%; Zirconium (Zr) <0.3%; Crome (Cr) <0.3%; Nickel (Ni) <2.0%; Cobalt (Co) <2.0%; Bismuth (Bi) <0.5%; Yttrium (Y) <0.5%; Magnesium (Mg) in the range of 0.3% to 3.0%; other elements <0.05% each and 0.15 in total; Aluminum remains (Al), and the filler alloy has a composition by weight:

Silicon (Si) between 4.0% and 15.0%; at least one of Silver (Ag), Beryllium (Be), Bismuth (Bi), Cerium (Ce), Lanthanum (La), Lead (Pb), Palladium (Pd), Antimony (Sb), Yttrium ( Y) or mischmetal between 0.01% and 1.0%; Aluminum remains (Al).

According to one embodiment, the core alloy has a magnesium content (Mg) of 0.5%, a silicon (Si) of 0.5%, a copper content (Cu) of 0.5%, a Manganese content (Mn) of 1.65%, a titanium (Ti) content of 0.08% and a Bismuth content (Bi) of 0.15%. The heat exchanger can be of the radiator type with a tube thickness ≤200μm.

This is usually a gas / liquid type exchanger.

The heat exchanger can be of the charge air cooler type with a tube thickness ≤270μm. This is usually a gas / gas type exchanger.

The method may comprise a step of using spacers of thickness selected in a range from about 50μm to about 100μm.

The invention also relates to a heat exchanger of the radiator type and a heat exchanger of charge air cooler type. The heat exchanger comprising substantially aluminum (Al) components. The components comprising a bundle of tubes, spacers between the tubes of said bundle and at least one collector plate, said spacers and said collector plates being separated by a minimum deviation of stress. According to the invention, the thickness of the tubes is ≤200 μm for the heat exchanger of the radiator type and is ≤270 μm for the heat exchanger of the charge air cooler type.

According to one embodiment, the minimum distance of stress is ≤3mm. This increases the heat exchange surface and therefore increases the performance of the exchanger.

According to another embodiment, the heat exchanger comprises spacers of thickness chosen in a range from about 50 μm to about 100 μm.

SUBSTITUTE SHEET (RULE 26) The tubes of the exchanger may consist of a core alloy of composition by weight:

Silicon (Si) between 0.5% and 0.7%; Iron (Fe) <1.0%; Copper (Cu) of between 0.3% and 1.0%; Manganese (Mn) from 0.3% to 2.0%; Zinc (Zn) <6.0%; Titanium (Ti) <0.1%; Zirconium (Zr) <0.3%; Crome (Cr) <0.3%; Nickel (Ni) <2.0%; Cobalt (Co)

<2.0%; Bismuth (Bi) <0.5%; Yttrium (Y) <0.5%; Magnesium (Mg) in the range of 0.3% to 3.0%; other elements <0.05% each and 0.15 in total; Aluminum remains (Al).

At least one of the components may be coated on at least one side of a filler alloy composed essentially of aluminum of composition by weight: silicon (Si) of between 4.0% and 15.0%; at least one of the following Silver

(Ag), Beryllium (Be), Bismuth (Bi), Cerium (Ce), Lanthanum (La), Lead (Pb), Palladium (Pd), Antimony (Sb), Yttrium (Y) or mischmetal between 0, 01% and 1.0%; Aluminum remains (Al).

According to one embodiment, the core alloy has a magnesium (Mg) content of 0.5%. By way of example, the tubes consist of a metal foil, comprising said core alloy and said supply alloy, folded on itself so as to define at least one fluid circulation channel, for example two channels, at least two parts of said folded sheet, provided vis-a-vis, being brazed along the longitudinal axis of said tube to seal said channel or channels. Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings in which:

FIG. 1 represents a schematic front view of a conventional heat exchanger,

2 schematically represents the thickness of the tubes and spacers, FIG. 3 relates to the prior art and graphically represents the breaking strength and the brazing ratio as a function of the magnesium content of an alloy. lady,

FIG. 4 shows a flowchart of one embodiment of the method of the invention,

FIG. 5 relates to the invention and graphically represents the breaking strength and the brazing ratio as a function of the magnesium content of a core alloy,

SUBSTITUTE SHEET (RULE 26) FIG. 6 is relative to the prior art and represents a graph relating the minimum and maximum distance between fins and collector plates for different classes of heat exchanger,

- Figure 7 relates to the invention and shows a graph relating the minimum and maximum distance between fins and collector plates for different classes of heat exchanger.

The drawings and the description below contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the present invention, but also contribute to its definition, if any. Figure 1 shows a schematic front view of a conventional heat exchanger 1. It appears different components and in particular a bundle of tubes 2, spacers 3 between the tubes of said bundle and at least one manifold plate 4, said spacers 3 and said collector plates 4 being spaced a minimum deviation of stress d _cont . The minimum deviation of stress is intended to compensate for mechanical deformations in the vicinity of the collector plates. Indeed, the collector plates being particularly sensitive to mechanical deformations a minimum deviation of stress protects the tubes vis-à-vis cracks and / or breaks.

FIG. 1 distinguishes two types of spacers 3: fins-type spacers 31 located between the tubes 2 and whose main role is to increase the exchange surface between the fluids, and spacers of the same type. turbulence says

"Turbulators" 32 located inside the tubes 2 and whose main role is to homogenize the contact surface between the fluid flowing inside the tubes 2 and the tube walls. The fins 31 and the turbulators 32 optimize the performance of a heat exchanger. Figure 2 schematically shows what is meant in this description by the thickness of the tubes e _tub . and the thickness of the spacers e _int .. Figure 2 also shows what is meant here by Tube Height H _tUb and _Tubing Width Lg _tub .

We now return briefly to the brazing techniques. Soldering is the assembly of components using a filler alloy (also called plating). The filler alloy has a lower melting temperature than the components to be assembled. Generally, soldering is done in an air oven, under a controlled atmosphere or under vacuum.

SUBSTITUTE SHEET (RULE 26) In the past, brazing was very commonly done under vacuum. However, this is associated with a very high cost due to the maintenance of vacuum furnaces. A new controlled atmosphere soldering technology with a non-corrosive flow, commonly known as Nocolok® (registered trademark), has subsequently replaced vacuum solder brazing. Flow means a mixture of chemicals to ensure satisfactory wetting of the alloy on the components to be assembled. The good wetting is due in particular to the elimination of the oxides present on the components to be assembled, the protection of the components to assemble oxidation during the duration of a brazing operation and by lowering the surface tension of the alloy. bring.

Among the components described here, there is at least one component made of a so-called alloy core alloy. In particular, reference will be made to tubes made of a well-chosen core alloy (see below).

The Nocolok process however imposes strict constraints on the use of alloys. Indeed alloys comprising magnesium (Mg) are subject to problems when using flux soldering. In fact, magnesium reacts with other chemical elements involved in flux brazing and in particular with fluorine, resulting in ineffective flux brazing from a magnesium content of about 0.3% by weight. weight in the composition of the components to be assembled. Beyond 0.3% magnesium, a greater amount of flux would be necessary, which would make the soldering operation more expensive and more difficult to control.

The document WO 2005/061743 has come to introduce a process for assembling aluminum alloy sheet comprising solder without flux under a controlled atmosphere, in which at least one sheet consists of a core alloy of well composition. chosen and in which at least one of the sheets is coated on at least one side of a brazing aluminum alloy of a well-chosen composition.

The Applicant has discovered, not without surprise, that the use of a brazing process with precise temperature conditions and a choice in percentage of the chemical composition of the separate components of a heat exchanger made it possible to reduce considerably the thickness of said components and thus an innovative dimensional assembly of heat exchangers.

The resistance to mechanical stresses described above is directly related to the brazing rate. The brazing rate corresponds to the percentage of assembly between the components to be assembled during the soldering operation. For good resistance to

SUBSTITUTE SHEET (RULE 26) mechanical constraints, it is particularly important to have a good connection between spacers and tubes.

The lower the brazing rate, the higher the risk of mechanical deformations and cracking and / or rupture of the tubes when the heat exchanger is in operating condition. It therefore tends to a brazing rate ≥95% to ensure satisfactory resistance to said constraints.

FIG. 3 relates to the prior art and shows a graph relating, on the one hand, the breaking strength (Rm) as a function of the magnesium percentage (Mg) in a core alloy on the one hand and of on the other hand, the relationship between the brazing rate and the percentage of magnesium (Mg) in a core alloy when using a Nocolok® brazing process.

The breaking strength (Rm) corresponds to the tensile stress from which the core alloy breaks in two parts, it is expressed in Mpa. It appears in Figure 3 that the breaking strength of a core alloy increases proportionally with the magnesium content (Mg) of said core alloy. However, with this increase in magnesium content (Mg) in the core alloy, the brazing rate is decreased until a brazing rate of less than 95% is reached at a content of approximately 0.3% by weight. . This is not satisfactory to ensure sufficient resistance to mechanical stresses occurring when the heat exchanger is in operation. To compensate for this lack of resistance to mechanical stresses, one solution is to increase the thickness of the material forming the tubes. But this would directly increase the cost of the process because of the surplus material.

The method of manufacturing a heat exchanger according to the invention makes it possible to increase the magnesium content (Mg) in the components of the heat exchanger, without disturbing the soldering rate.

The flowchart of FIG. 4 shows an embodiment of the method of the invention. Operation 400 comprises the provision of components to form a heat exchanger, namely including tubes, spacers and collector plates. The tubes are substantially selected from a specific core alloy during a selection step 402 and whose magnesium content (Mg) is between 0.3% and

3.0% by weight.

The core alloy of the tubes may have the following composition by weight: Silicon (Si) = 0.5%; Iron (Fe) <1.0%; Copper (Cu) = 0.5%; Manganese (Mn) = 1.65%; Zinc (Zn)

SUBSTITUTE SHEET (RULE 26) 6.0%; Titanium (Ti) = 0.08%; Zirconium (Zr) <0.3%; Crome (Cr) <0.3%; Nickel (Ni) <2.0%; Cobalt (Co) <2.0%; Bismuth (Bi) <0.5%; Yttrium (Y) <0.5%; Magnesium (Mg) = 0.5%; other elements <0.05% each and 0.15 in total; Aluminum remains (Al). This alloy composition is known as the "fluxless alloy". In a subsequent thickness selection operation 404, the thickness of the tubes e _tub is chosen. In the case of radiator-type heat exchangers, the thickness e _tub is chosen between 170 μm and 230 μm, and preferably between 170 μm and 200 μm. In the case of heat exchangers of charge air cooler type, the thickness e _tUb is chosen between 270 μm and 400 μm, and preferably about 270 μm. Thickness selection operation 404 also includes the thickness _selection of tabs. The fins-type spacers are chosen between 50 .mu.m and 100 .mu.m, the interleaves of turbulators type are chosen between 70 .mu.m and 100 .mu.m.

A filler alloy deposition step 406 comprises depositing a filler alloy on at least one face of at least some of the components for solder assembly. The filler alloy may have the following composition by weight: Silicon (Si) of between 4.0% and 15.0%; at least one of Silver (Ag), Beryllium (Be), Bismuth (Bi), Cerium (Ce), Lanthanum (La), Lead (Pb), Palladium (Pd), Antimony (Sb), Yttrium ( Y) or mischmetal (alloy between metals and rare earths) between 0.01% and 1.0%; Aluminum remains (Al). The following assembly operation 408 comprises the mechanical positioning of the components of the heat exchanger for carrying out the final brazing operation 410.

FIG. 5 shows the relationship between fracture strength (Rm) and magnesium percentage (Mg) in a core alloy on the one hand and the relationship between the solder ratio and the solder ratio on the other hand. the percentage of magnesium (Mg) in a core alloy when implementing the method of the invention as described above. According to the embodiment described here, the method of the invention uses a core alloy whose magnesium content (Mg) can easily reach 0.5% by weight while maintaining a brazing rate greater than 95%. The breaking strength of the alloy is then around 220 MPa.

Figure 6 relates to the prior art and shows the minimum gap _∞nt d and the maximum deviation of a type of intermediate fin of different classes of heat exchangers, which will not be detailed herein. Note that the minimum distance between fins and collector plates is 3mm. As mentioned above, this is

SUBSTITUTE SHEET (RULE 26) a minimum safety distance to minimize the risk of cracking and / or breaking during mechanical deformation in the vicinity of the collector plate.

FIG. 7 relates to the invention and also shows the minimum distance d _{∞ nt} and the maximum gap of a fin type interlayer of different classes of heat exchangers when the heat exchanger is assembled by the method of the invention. It can be seen that the assembly of a heat exchanger with the method of the invention makes it possible to lower the minimum safety distance between the collector plates and the fins-type spacers. This makes it possible to increase the heat exchange surface and thus the performance of a heat exchanger. In the following, the invention will be described with the aid of an exemplary embodiment. Advantages of the invention will emerge clearly in the light of the nonlimiting exemplary embodiment described below.

Example

Mechanical tests were carried out on the one hand on heat exchangers of the radiator type and charge air cooler type, assembled by a conventional Nocolok brazing process and whose core alloy (in particular the tubes ) have a known composition of conventional type aluminum alloy type 3000 series modified, and secondly on radiator-type heat exchangers and charge air cooler type, assembled according to one embodiment of the method of the invention (see below) and whose core alloy (especially the tubes) is the fluxless alloy described above.

Description of the mechanical tests carried out:

1. Cycled pressure test: the exchangers are subjected to alternating internal cycled pressures in heated or unheated enclosure so as to show or not fatigue resistance problems and must meet a minimum number of cycles without rupture imposed by each client.

2. Thermal Shock Test: the exchangers are subjected to an internal fluid circulation at alternating temperatures for the purpose of highlighting the differential expansion phenomena between the different components of said exchanger. The number of cycles of alternating temperature without break is also imposed by the specifications of the customer.

Mechanical tests were carried out on different models of heat exchangers, namely for:

SUBSTITUTE SHEET (RULE 26) - heat exchangers radiator type the following models: 14mm; 18mm; 27mm and 34mm, and for

- charge air cooler type heat exchangers the following models: - 64mm; 80mm compact; 80mm mosaic and 100mm.

The models are mainly defined by the range of tubes used, in particular the width of the tubes Lg _n ^ and the structure of the bundle, that is to say a combination between the number of tubes / spacers, and the lengths of said tubes. .

In the embodiment of the example described here, it was used a standard 4000 type filler alloy and more precisely 4045 (10% silicon) with a content of

Bismuth (Bi) substantially equal to 0.15%. The filler alloy covers the core alloy and is about 10% of the total thickness of the core alloy / filler alloy assembly.

The core alloy / alloy alloy assembly of the embodiment described is first hot-rolled and then cold-treated, and then subjected to a heat-treatment treatment.

Approximately 10 h at 26O ⁰ C. A 10 min degreasing treatment at 240 ^° C. is applied to the solder alloy / solder alloy assembly. No other surface preparation is applied and in particular no Flux is deposited. Brazing is done in a double-walled glass furnace that actively tracks the progress of the assembly. The thermal cycle is composed of a temperature rise phase up to 600 ° C. with a speed of about 20 ^° C. to 30 ° C./min, of a hold of 2 minutes at 600 ° C., and of a descent to about 60 ° C / min. The process of the described embodiment is carried out under continuous nitrogen sweep.

It should be noted that the operating conditions for assembling by brazing the above conditions must be substantially respected in order to provide a satisfactory brazing rate.

(> 95%)

In a first series of mechanical tests, different thicknesses of interlayers _int were arranged on the heat exchangers.

For the first series of mechanical tests on heat exchangers radiator type, the thickness of the tubes e _tub is 270 .mu.m. Three different thicknesses of fins were used, namely:

SUBSTITUTE SHEET (RULE 26) - 50μm; 70μm and 100μm.

For the first series of mechanical tests on charge air cooler type heat exchangers, the thickness of the tubes is 400 μm. The fin thickness was chosen constant, namely: 70 μm. Two different thicknesses of turbulators have been used, namely:

- 70μm and 100μm.

The results of the first series of mechanical tests on radiator-type heat exchangers are shown in Table 1.

The results of the first series of mechanical tests on charge air cooler heat exchangers are shown in Table 2.

Table 1. "+": resistance to mechanical stress ensured; "-": resistance moderately to mechanical stresses; "0": non-resistance to mechanical stresses.

By mechanical strength is meant in these tables the fact that the product (in the given configuration) passes the mechanical tests mentioned above without any break observed.

SUBSTITUTE SHEET (RULE 26)

Table 2. "+": resistance to mechanical stress ensured; "-": resistance moderately to mechanical stresses; "0": non-resistance to mechanical stresses.

The results of the first series of mechanical tests on heat exchangers show that the method of the invention allows obtaining stable and robust exchangers heats while using a reduced thickness e of tube _tub, irrespective of the model heat exchanger. This is explained by the high magnesium content in the tubes. Therefore, as shown in Tables 1 and 2, the thickness e _ιnt spacers can be reduced to the exchangers models whose width Lg tubes _tub is large (about 27mm or 34mm).

In a second series of mechanical tests, different thicknesses of _tubular tubes were arranged on the heat exchangers. For the second series of mechanical tests on radiator-type heat exchangers, the thickness of the tab-type spacers is _{70 μm} . Three different thicknesses of tubes and _tUb were used, namely:

- 180μm; 200μm and 230μm.

For the second series of mechanical tests on charge air cooler heat exchangers, the thickness of the fin or turbulator type spacers is 70 .mu.m. Two different thicknesses of tubes have been used, namely:

270μm and 400μm.

SUBSTITUTE SHEET (RULE 26) The results of the second series of mechanical tests on radiator heat exchangers are shown in Table 3.

The results of the second series of mechanical tests on charge air cooler heat exchangers are shown in Table 4.

SUBSTITUTE SHEET (RULE 26)

Table 3. "+": resistance to mechanical stress ensured; "-": resistance moderately to mechanical stresses; "0": non-resistance to mechanical stresses.

Table 4. "+": resistance to mechanical stress ensured; "-": resistance moderately to mechanical stresses; "0": non-resistance to mechanical stresses. "? ": Untested.

SUBSTITUTE SHEET (RULE 26) The results of the second series of mechanical tests on the heat exchangers confirm that the process of the invention allows the use of reduced thickness tubes. As a result, construction equipment is saved, which is of great economic interest.

The invention applies mainly to heat exchangers for motor vehicles, in particular engine cooling radiators and charge air coolers.

SUBSTITUTE SHEET (RULE 26)

Claims

claims

A method of manufacturing a heat exchanger (1) comprising substantially aluminum (Al) components, said components comprising a bundle of tubes (2), spacers (3) between and / or in the tubes (2) said beam and at least one collecting plate (4), characterized in that the method comprises the following steps:

- choose tubes (2) made of an aluminum core alloy and comprising magnesium (Mg) of between 0.3% and 3.0% by weight and other chemical elements,

- choose a thickness of said tubes (e _tUb ) regardless of the thickness of said spacers (e _in t),

- coating at least one side of at least some of said components of an aluminum-based filler alloy, and - assembling said components by fluxless soldering under a controlled atmosphere at a temperature between 580 ^c C and 620 ⁰ C followed cooling.

2. Method according to claim 1, characterized in that the core alloy has a composition by weight: Si (Si) between 0.5% and 0.7%; Iron (Fe) <1.0%; Copper (Cu) between

0.3% and 1.0%; Manganese (Mn) from 0.3% to 2.0%; Zinc (Zn) <6.0%; Titanium

(Ti) <0.1%; Zirconium (Zr) <0.3%; Crome (Cr) <0.3%; Nickel (Ni) <2.0%; Cobalt (Co)

3. Method according to one of the preceding claims, characterized in that the filler alloy has a composition by weight:

Silicon (Si) between 4.0% and 15.0%; at least one of the following elements Silver (Ag), Beryllium (Be), Bismuth (Bi), Cerium (Ce), Lanthanum (La), Lead (Pb), Palladium

SUBSTITUTE SHEET (RULE 26) (Pd), Antimony (Sb) ₁ yttrium (Y) or mischmetal between 0.01% and 1.0%; Aluminum remains (Al).

4. Method according to one of claims 1 to 3, characterized in that the heat exchanger (1) is of the radiator type and in that the thickness of said tubes (2) is ≤200μm.

5. Method according to one of claims 1 to 3, characterized in that the heat exchanger (1) is of the charge air cooler type and in that the thickness of said tubes e _tUb is ≤270μm.

6. Method according to one of the preceding claims, characterized in that the thickness of said spacers (e _int ) is chosen in a range from about 50μm to about 100μm.

7. Method according to one of the preceding claims, characterized in that the magnesium content (Mg) of the core alloy is 0.5%.

8. Method according to one of the preceding claims, characterized in that the silicon content (Si) of the core alloy is 0.5%.

9. Method according to one of the preceding claims, characterized in that the copper content (Cu) of the core alloy is 0.5%.

10. Method according to one of the preceding claims, characterized in that the Manganese content (Mn) of the core alloy is 1.65%.

11. Method according to one of the preceding claims, characterized in that the titanium content (Ti) of the core alloy is 0.08%.

SUBSTITUTE SHEET (RULE 26)

12. Method according to one of the preceding claims, characterized in that the Bismuth (Bi) content of the filler alloy is 0.15%.

13. Heat exchanger (1) of the radiator type comprising components essentially made of aluminum (Al), said components comprising a bundle of tubes (2), spacers (3) between the tubes (2) of said bundle and at least one plate collector (4), said spacers (3) and said collector plates (4) being remote from a minimum deviation of stress characterized in that the thickness of said tubes (2) is ≤200μm.

14. Heat exchanger (1) of charge air cooler type comprising mainly aluminum components (Al), said components comprising a bundle of tubes (2), spacers (3) between the tubes (2) of said bundle and at least one collector plate (4), said spacers (3) and said collector plates (4) being spaced apart by a minimum deviation of stress (dco _n t). characterized in that the thickness of said tubes is <270μm.

15. Heat exchanger (1) according to claim 13 or 14, characterized in that the spacers (3) and the or the collector plates (4) are _spaced a minimum deviation of stress (d _∞nt ) ≤3mm.

16. Heat exchanger (1) according to one of claims 13 to 15, characterized in that the thickness of said spacers (e _int ) is chosen in a range from about 50μm to about 100μm.

17. Heat exchanger (1) according to one of claims 13 to 16, characterized in that the tubes (2) consist of a core alloy of composition by weight:

Silicon (Si) between 0.5% and 0.7%; Iron (Fe) <1.0%; Copper (Cu) of between 0.3% and 1.0%; Manganese (Mn) from 0.3% to 2.0%; Zinc (Zn) <6.0%; Titanium

SUBSTITUTE SHEET (RULE 26) (Ti) <0.1%; Zirconium (Zr) <0.3%; Crome (Cr) <0.3%; Nickel (Ni) <2.0%; Cobalt (Co) <2.0%; Bismuth (Bi) <0.5%; Yttrium (Y) <0.5%; Magnesium (Mg) in the range of 0.3% to 3.0%; other elements <0.05% each and 0.15 in total; Aluminum remains (Al), at least one of said components being coated on at least one side of a substantially aluminum alloy of composition by weight:

18. Heat exchanger (1) according to one of claims 13 to 17, characterized in that the magnesium content (Mg) of the core alloy is 0.5%.

SUBSTITUTE SHEET (RULE 26)