Heat exchange plate with structural plate for battery pack

Abstract

The invention relates to a heat exchange plate (10) for thermal management of a battery pack (200), comprising a first plate (20) and a second plate (30), at least the first plate (20) comprising at least one channel (40), the first plate (20) and the second plate (30) being contiguous such that the channel (40) partially delimits at least one duct for a circuit for circulation of a heat transfer fluid, characterized in that the first plate (20) and the second plate (30) are connected to each other. The first plate (20) is made of a first material and the second plate (30) is made of a second material that is different from the first material and imparts a structural function to the second plate (30).

Description

Technical Field

[0001] The present invention relates to thermal regulation of batteries and more particularly to heat exchange plates for thermal management of battery packs, particularly in the automotive field. Background Art

[0002] Thermal regulation of cells and battery packs, particularly in the automotive sector and even more particularly in the sector of electric and hybrid vehicles, is a matter of importance since, if the cells are subjected to too cold temperatures, their autonomy can drop drastically, and if they are subjected to too high temperatures, there is a risk of thermal runaway which could even damage the cells.

[0003] In order to regulate the temperature of the battery, it is known to add devices for regulating the temperature of the battery module. These devices generally use a heat transfer fluid that circulates, for example by means of a pump, in a pipe loop that passes in particular under or inside the heat exchange plates that are in direct contact with the battery.

[0004] The heat transfer fluid can thus absorb the heat dissipated by one or more batteries in order to cool them and discharge this heat at one or more heat exchangers (such as radiators or refrigerants). If necessary, the heat transfer fluid can also supply heat to heat the battery, for example if the battery is connected to a resistor or a positive temperature coefficient (PTC) heater.

[0005] The heat transfer fluid commonly used is ambient air or a liquid, such as water. Since liquids are better conductors of heat than gases, this is an advantageous solution as it is more efficient.

[0006] Typically, a heat exchange plate in direct contact with the battery cells is placed below the battery, which thus rests on it. The heat exchange plate is typically made of metal and consists of two metal plates pressed against and brazed against each other so as to form one or more circuits of ducts for the circulation of a heat transfer fluid between a fluid inlet and an outlet.

[0007] In order to allow the mechanical strength of the battery pack, the battery pack provided with a battery cooler exchanger must be connected to structural elements and must be protected from external elements. This function, called "structure", is currently ensured by an assembly of beams, cross members and protectors (structural panels positioned below the heat exchange plates). This structural assembly allows resistance to crash tests and impacts, but also to the loads of the battery modules on the battery cooler. The elements constituting the structural function are manufactured in a known manner from materials that provide very excellent mechanical properties, such as elastic limit (Rp0.2) and breaking strength (Rm).

[0008] However, the manufacture of the structural panel supports and the elements required to fasten the battery pack to the beams represents an additional cost to the motor vehicle manufacturer, and their use increases the weight of the vehicle and therefore increases CO2 emissions. Summary of the invention

[0009] One of the objects of the present invention is to propose a heat exchange plate that at least partially remedies the disadvantages of the prior art and to propose a structural heat exchange plate while respecting the objectives of recyclability and seeking carbon neutrality.

[0010] Therefore, the present invention relates to a heat exchange plate for thermal management of a battery pack, the heat exchange plate having a first plate and a second plate, at least the first plate having at least one channel (the first plate includes a protrusion that forms at least one channel when combined with the second plate), the first plate and the second plate being adjacent to each other so that the channel partially defines at least one conduit of a circuit for circulation of a heat transfer fluid, and wherein the first plate is made of a first material and the second plate is made of a second material, the second material being different from the first material and imparting structural functionality to the second plate.

[0011] Such a structural heat exchange plate makes it possible to reduce the number of transverse members and elements (casings, attachment points, reinforcements, beams, etc.) required for assembling the battery modules and for the mechanical strength of the battery pack.

[0012] The structural heat exchange plate according to the invention therefore makes it possible to achieve cost savings, mass savings and a reduction in CO 2 emissions for motor vehicle manufacturers.

[0013] Further optional features taken individually or in combination depending on the hot plate:

[0014] The first material has a lower elastic limit than the second material, making it possible to avoid brazing steps that lead to deformations of the thermoplate and thus making it possible to adhere to the desired dimensions of the thermoplate.

[0015] The second material has an elastic limit (Rp0.2) greater than 190 MPa, preferably greater than 200 MPa.

[0016] The second material has a breaking strength (Rm) greater than 220 MPa, preferably greater than 240 MPa.

[0017] - The second material has an elongation at break (A %) greater than 22%.

[0018] - The first material and the second material are metallic materials.

[0019] - The first material and the second material are aluminum alloys, thereby allowing the first plate and the second plate to be Assembled by brazing process.

[0020] The second material consists essentially, preferably at least 95%, of an aluminium alloy of the 6000 series.

[0021] The first material consists essentially, preferably at least 95%, of an aluminium alloy of the 3000 series.

[0022] At least one of the faces of at least one of the plates has an anti-corrosion layer.

[0023] - The anti-corrosion layer is made of aluminum alloy of 1000 series, 3000+Zn series or 7000 series.

[0024] - When the anti-corrosion layer is made of an aluminum alloy of the 3000+Zn series, the Zn concentration is between 0.5% and 1.8%.

[0025] At least one of the faces of the second plate has a magnesium barrier layer.

[0026] - The barrier layer is made of aluminum alloy of the 1000 series, 3000+Zn series or 7000 series.

[0027] At least one of the faces of the second plate has a magnesium barrier layer, preferably made of an aluminium alloy of the 1000 series, 3000+Zn series or 7000 series.

[0028] - When the barrier layer is made of an aluminum alloy of the 3000+Zn series, the Zn concentration is between 0.5% and 1.8%.

[0029] At least one of the inner faces of at least one of the plates has a brazing layer.

[0030] The brazing layer is made of an aluminum alloy of the 4000 series, preferably a 4343 or 4045 aluminum alloy.

[0031] The second plate ( 30 ) has on each of its faces a layer made of an aluminium alloy of the 7000 series (preferably 7072) or 3000+Zn series (preferably 3003+Zn series).

[0032] When each of the faces of the second plate ( 30 ) has a layer made of an aluminium alloy of the 3000+Zn series, the Zn concentration is between 0.5% and 1.8%.

[0033] The invention also relates to a method for manufacturing a heat exchange plate as described above, the method involving the following steps:

[0034] i- producing a first plate using a first material and producing a second plate using a second material;

[0035] ii- forming at least one channel on at least one of the first plate and the second plate, preferably by pressing;

[0036] iii- assembling the two plates in a sealed manner; and

[0037] iv- Applying at least one treatment, such as artificial aging of the assembled components by heat treatment, in order to improve the structural properties.

[0038] According to further optional features of the method taken individually or in combination:

[0039] - Step ii) is performed by a stamping process.

[0040] - Step iii) by means of a brazing process, preferably Brazing execution.

[0041] - Step iv) involves heat treatment of the hot plate.

[0042] - The heat treatment involved a step of heating on a hot plate at 225°C for 45 minutes.

[0043] - Using a second material mainly comprising an aluminum alloy of the 6000 series.

[0044] - Step i) involves a step of covering at least one of the faces of at least one of the plates with at least one functional layer, this at least one functional layer being of the anti-corrosion, magnesium barrier and / or brazing type. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other characteristics and advantages of the invention will become more clearly apparent from a reading of the following description, given by way of illustrative and non-limiting examples, and of the accompanying drawings, in which:

[0046] Figure 1 shows a schematic perspective view of a heat exchange plate according to the invention,

[0047] Figure 2 yes Figure 1 Detail showing part of the channels of the heat exchange plate,

[0048] Figure 3 shows a schematic exploded perspective view of a heat exchange plate according to an embodiment,

[0049] Figure 4 is a set of pictures ( Figure 4 A to Figure 4 C), showing an exemplary superposition of (corrosion protection and brazing) layers around the core of a first plate,

[0050] Figure 5 is a set of pictures ( Figure 5 A to Figure 5 C), showing an exemplary superposition of (corrosion protection and barrier) layers around the core of the second plate,

[0051] Figure 6 is a diagram illustrating the various steps of an exemplary method for manufacturing a thermal plate according to the present invention.

[0052] In the various figures, identical elements are provided with identical reference numerals. DETAILED DESCRIPTION

[0053] like Figure 1 and Figure 2 As shown, a heat exchange plate 10 for thermal management of a battery pack 200 has a first plate 20 (“channel plate”) and a second plate 30 (“base plate”).

[0054] At least one of the first plate 20 and the second plate 30 has a channel 40. Figure 1 In the example of , the first plate 20 is then intended to be in contact with the battery pack 200 .

[0055] According to an exemplary embodiment, the plates 20 and 30 of the thermoplate 10 have a substantially rectangular shape, with a length of 1700 mm and a width of 1300 mm. Each plate has a thickness between 0.5 mm and 2 mm.

[0056] The first plate 20 and the second plate 30 are adjacent to each other so that the channel 40 defines a duct of a circuit for the circulation of a heat transfer fluid. Preferably, the duct is U-shaped and extends between a heat transfer fluid inlet and an outlet, each formed by a connecting pipe.

[0057] The heat exchange plate 10 may also have retaining elements (not shown) allowing said exchange plate to be fastened to a battery pack or a battery. The heat exchange plate 10 may also have a seal 50 placed between the first plate 20 and the second plate 30 in order to ensure a seal therebetween.

[0058] The battery pack 200 should be understood to mean a group of battery cells that are electrically connected to each other and form the battery pack 200 , or a large-sized single battery.

[0059] According to the invention, the first plate 20 is made of a first material, and the second plate 30 is made of a second material which is different from the first material and which imparts a structural function to the second plate 30 .

[0060] In order to obtain this structural function, a second material is used whose elastic limit (Rp0.2) is greater than 190 MPa, preferably greater than 200 MPa.

[0061] This elastic limit (Rp0.2) is measured according to the standardized ISO:6892-1 method.

[0062] Preferably, the second material also has a breaking strength (Rm) greater than 220 MPa, preferably greater than 240 MPa.

[0063] This breaking strength (Rm) is measured according to the standardized ISO:6892-1 method.

[0064] Preferably, the second material also has an elongation at break (A%) greater than 22%.

[0065] This elongation at break (Rm) is measured according to the standardized ISO:6892-1 method.

[0066] As regards the first material, it is selected from a material having a lower elastic limit than the second material. The value of the elastic limit is selected so as to relieve at least some of the stresses caused by the second plate 30 having a structural function.

[0067] Preferably, materials are used that are compatible with the current process for forming the plates (i.e. pressing) and the current process for manufacturing the heat exchange plates (i.e. brazing). Thus, the first material and the second material are selected from metals. Preferably, the first material and the second material are selected to allow for The brazing process assembles the two plates 20 and 30 .

[0068] According to a preferred embodiment, the second material mainly comprises, preferably at least 95% (particularly for recycling reasons), an aluminum alloy of the 6000 series, the alloying elements of which are magnesium and silicon. In particular, this alloy provides mechanical properties superior to the aluminum alloys of the 3000 series conventionally used to manufacture the two plates of the heat exchanger plate.

[0069] By virtue of its excellent mechanical properties, and in particular its stiffness, the 6000 type of aluminium confers structural functionality to the hot plate 1. However, since aluminium alloys of the 6000 series do not deform during mechanical strength tests, the use of such material for the second plate 30 may, depending on the design of the hot plate 1, lead to a significant increase in local forces and therefore to failures or even fractures in mechanical strength tests (pressure cycles, vibrations, burst strength, etc.). This is because, in particular during fatigue tests, it is known that the stress values ​​of a "harder" material with a low level of elongation at break (A%) will increase locally, since it is less easily deformed and allows less "bulging" of the part, and is therefore less resistant to fatigue tests.

[0070] Therefore, according to this preferred embodiment, the first material of the first plate 20 is a 3000 series aluminum alloy, so that at least some of the stresses caused by the second plate 30 having a structural function can be relieved.

[0071] According to certain embodiments, additional layers are applied to panels 20 and 30. These embodiments are Figure 4 and Figure 5 and described below.

[0072] Anti-corrosion layer 80

[0073] according to Figure 4 and Figure 5 In one embodiment shown, each plate 20 , 30 is covered with an anti-corrosion layer 80 on at least one of the two faces, preferably on both faces, so that the core 60 , 70 of the plate made of the first material and the second material can be protected.

[0074] Figure 4 A shows the superposition of the layers forming the first plate 20 when the core 60 made of the first material is covered with a single anti-corrosion layer 80 .

[0075] Figure 4 B shows the superposition of the layers forming the first plate 20 when the core 60 made of the first material is covered on both faces thereof with the anti-corrosion layer 80 .

[0076] Figure 5 A shows the superposition of layers forming the second plate 30 when a core 70 made of the second material is covered with a single anti-corrosion layer 80 .

[0077] Figure 5 B shows the superposition of layers forming the second plate 30 when the core 70 made of the second material is covered with the anti-corrosion layer 80 on both faces thereof.

[0078] According to an exemplary embodiment, the anti-corrosion layer 80 is made of an aluminum alloy of the 1000 series, 3000+Zn series or 7000 series. This layer acts as a sacrificial layer for resisting internal and / or external corrosion. The advantage of the layer of the 3000+Zn series is that it maintains the mechanical properties provided by the core alloy.

[0079] The thickness of the anti-corrosion layer 80 is between 2.5% and 10% of the plate thickness.

[0080] Layer 90 forming a magnesium diffusion barrier (second plate)

[0081] When the second material is rich in magnesium, it is important that the magnesium remains in the core 70 made of the second material in order to maintain the structural properties of the material. However, during the brazing step necessary to assemble the two plates 20 and 30, magnesium has a tendency to escape and migrate from the core 70 made of the second material.

[0082] Therefore, according to Figure 5In one embodiment shown in C, the second plate 30 is covered on at least one of its two faces, preferably on both faces, with a barrier layer 90, which acts as a magnesium diffusion barrier during the brazing process. The magnesium is thus retained in the core of the second layer made of the second material and thus retains its structural properties.

[0083] According to an exemplary embodiment, the barrier layer 90 , like the anti-corrosion layer 80 , is made of an aluminum alloy of the 1000 series, 3000+Zn series, or 7000 series.

[0084] The thickness of the barrier layer 90 is between 2.5% and 10% of the thickness of the plate.

[0085] Solder layer 100 (first plate)

[0086] according to Figure 4 In one embodiment shown in FIG. 3C , at least one of the first plate 20 and the second plate 30 is covered with a brazing layer 100 on one face thereof (the face being positioned to face the other plate), so that the brazing process can be optimized.

[0087] According to an exemplary embodiment, the brazing layer 100 is made of an aluminum alloy of the 4000 series (preferably 4343 or 4045).

[0088] The thickness of the solder layer 100 is between 2.5% and 10% of the plate thickness.

[0089] Figure 4 C shows the superposition of layers forming the first plate 20 when the core 60 made of the first material is covered with the anticorrosion layer 80 on both faces thereof and with the brazing layer 100 .

[0090] Exemplary Embodiments

[0091] Example 1

[0092] The anti-corrosion layer 80 is an aluminum alloy of the 7000 series, preferably 7072. The anti-corrosion layer 80 is applied to the outer face of the first plate 20 (not facing the plate 30) and the outer face of the second plate 30 (not facing the plate 20).

[0093] The inner face of the plate 20 is covered with a brazing layer made of an aluminium alloy of the 4000 series, preferably 4343 or 4045.

[0094] The core of the first plate is made of a 3000 series aluminum alloy.

[0095] The core of the second plate is made of a 6000 series aluminum alloy.

[0096] Example 2

[0097] The first plate 20 is a plate according to example 1, but the second plate 30 is covered on both faces with a layer made of an aluminium alloy of the 1000 series, 3000+Zn series or 7000 series, which layer is both a barrier layer and an anti-corrosion layer.

[0098] Example 3

[0099] The second plate 30 has a core made of 6060 aluminum alloy covered with a barrier layer made of 1050 aluminum alloy.

[0100] Example 4

[0101] In certain embodiments, the second plate 30 has a core made of a 6000 series aluminum alloy covered with a layer of 7072 aluminum alloy that acts as a barrier layer and corrosion protection layer.

[0102] Advantageously, this layer of 7072 aluminum alloy acts as a barrier layer so as to form a barrier to magnesium migration during the brazing process.

[0103] Advantageously, this layer of 7072 aluminum alloy acts as a sacrificial layer to meet corrosion requirements.

[0104] Finally, advantageously, a combination of an aluminum alloy of the 6000 series with a 7072 aluminum alloy is preferred, since it is particularly advantageous in terms of recyclability.

[0105] Use of a 3000+Zn layer may be beneficial for corrosion protection and maintaining mechanical properties, especially for reduced thicknesses.

[0106] Manufacturing method

[0107] The present invention also relates to a method for manufacturing a heat exchange plate 1 for thermal management of a battery pack 200 according to the present invention. Figure 6 As shown, the method involves the following steps:

[0108] i- producing a first plate 20 using a first material and producing a second plate 30 using a second material;

[0109] ii- forming at least one channel 30 on at least one of the first plate 20 and the second plate 30, for example by means of a stamping process;

[0110] iii- For example by means of a brazing process, preferably Brazing assembles the two plates in a sealed manner;

[0111] iv- Applying at least one treatment, such as artificial aging of the assembled components by heat treatment, in order to improve the structural properties.

[0112] According to one example, the heat treatment (step iv) comprises heating the hot plate 1 at 225° C. for 45 minutes.

[0113] According to a preferred embodiment, a second material mainly (preferably at least 95%) of an aluminum alloy of the 6000 series is used. Specifically, this alloy can be solidified by aging and can therefore be solidified by the brazing process (step iv) for assembling the two plates 20 and 30. Brazing serves as a solution heat treatment. In addition, the mechanical strength of the second plate 30 is improved and more excellent due to the artificial aging treatment (step v).

[0114] Advantageously, the method involves, in step i), covering the panels 20 and / or 30 with a functional layer:

[0115] - covering at least one of the faces of at least one of the plates 20 and 30 with an anti-corrosion layer 80; and / or

[0116] - covering at least one of the faces of the second plate 30 with a magnesium barrier layer 90; and / or

[0117] The inner face of at least one of the plates 20 and 30 (ie the face facing the other plate) is covered with a brazing layer 100 .

[0118] By applying this treatment to the hot plate 1 of Example 3 (the second plate 30 having a core 70 made of 6060 aluminum alloy covered with a barrier layer made of 1050 aluminum alloy), the following mechanical properties are obtained for a plate 30 with a thickness of 2 mm:

[0119] -Rp0.2: 196MPa

[0120] -Rm: 227MPa

[0121] -A50%:9.8

[0122] List of Reference Numerals

[0123] 10: Heat exchange plate for thermal management of battery packs

[0124] 20: The first plate of the heat exchange plate 10 ("channel plate")

[0125] 30: The second plate ("base plate") of the heat exchange plate 10

[0126] 40: Channel of heat exchange plate 10

[0127] 50: Sealing member of heat exchange plate 10

[0128] 60: a core made of the first material of the first plate 20

[0129] 70: a core made of the second material of the second plate 30

[0130] 80: Anti-corrosion layer

[0131] 90: Magnesium diffusion barrier

[0132] 100: Brazing layer

[0133] 200: Battery Pack

Claims

1. A heat exchange plate (10) for thermal management of a battery pack (200), the heat exchange plate having a first plate (20) and a second plate (30), at least the first plate (20) having at least one channel (40), the first plate (20) and the second plate (30) being adjacent to each other so that the channel (40) partially defines at least one conduit of a circuit for circulation of a heat transfer fluid, characterized in that The first plate (20) is made of a first material, and the second plate (30) is made of a second material, which is different from the first material and imparts a structural function to the second plate (30).

2. A heat exchange plate (10) according to the preceding claim, wherein The first material has a lower elastic limit than the second material.

3. A heat exchange plate (10) according to any one of the preceding claims, wherein: The second material has an elastic limit (Rp0.2) greater than 190 MPa, preferably greater than 200 MPa.

4. A heat exchange plate (10) according to any one of the preceding claims, wherein: The second material has a breaking strength (Rm) greater than 220 MPa, preferably greater than 240 MPa.

5. A heat exchange plate (10) according to any one of the preceding claims, wherein: The second material has an elongation at break (A%) greater than 22%.

6. A heat exchange plate (10) according to any one of the preceding claims, wherein The first material and the second material are aluminum alloys, thereby allowing the first plate (20) and the second plate (30) to be Assembled by brazing process.

7. A heat exchange plate (10) according to any one of the preceding claims, wherein The second material consists essentially, preferably at least 95%, of a 6000 series aluminum alloy.

8. A heat exchange plate (10) according to any one of the preceding claims, wherein: The first material consists essentially, preferably at least 95%, of a 3000 series aluminum alloy.

9. A heat exchange plate (10) according to any one of the preceding claims, wherein: At least one of the faces of at least one of the plates (20, 30) has an anti-corrosion layer (80), which is preferably made of an aluminum alloy of the 1000 series, 3000+Zn series or 7000 series.

10. A heat exchange plate (10) according to any one of the preceding claims, wherein At least one of the faces of the second plate (30) has a magnesium barrier layer (90), preferably made of an aluminum alloy of the 1000 series, 3000 series or 7000 series.

11. A heat exchange plate (10) according to any one of the preceding claims, wherein At least one of the internal faces of at least one of the plates (20, 30) has a brazing layer (100), preferably made of an aluminum alloy of the 4000 series, even more preferably of a 4343 or 4045 aluminum alloy.

12. A heat exchange plate (10) according to any one of the preceding claims, wherein: The second plate (30) has on each of its faces a layer made of an aluminum alloy of the 7000 series, preferably a 7072 aluminum alloy, or of an alloy of the 3000+Zn series.

13. A method for manufacturing a heat exchange plate (10) according to any one of the preceding claims, said method involving the following steps: i- producing said first plate (20) from said first material and producing said second plate (30) from said second material, said second material preferably mainly comprising an aluminium alloy of the 6000 series; ii- forming at least one channel (30) on at least one of said first plate (20) and said second plate (30), preferably by pressing; iii-preferably by brazing, even more preferably by Brazing assembles the two plates in a sealed manner; and iv- Applying at least one treatment, such as artificial aging of the assembled components by heat treatment, in order to improve the structural properties.

14. The method according to the preceding claim, wherein: Step i) involves the step of covering at least one of the faces of at least one of the plates (20, 30) with at least one functional layer of the anti-corrosion (80), magnesium barrier (90) and / or brazing (100) type.

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