Integrated cooling element for battery modules

Abstract

The housing for at least one heat generating element (100), for example a battery element for an electric vehicle, comprises a housing wall (200), a holder (300) connected to the housing wall (200) for receiving the at least one heat generating element (100), and a cooling body (400) arranged on a side of the housing wall (200) opposite the holder (300) and connected to the housing wall (200). The housing wall (200), the holder (300), and the cooling body (400) are provided as a whole as an integral part, wherein the cooling body (400) has at least one flow path (500) for a coolant, and at least one partial region of the cooling body (400) consists of a first thermoplastic polymer composition having a thermal conductivity of at least 0.2 W / (m K) as determined in accordance with ASTM E-01.

Description

[Technical field]

[0001] The invention relates to an enclosure for at least one heat generating element, comprising an enclosure wall, a holder connected to the enclosure wall for accommodating at least one heat generating element, and a cooling body arranged on a side of the enclosure wall opposite the holder and connected to the enclosure wall. The heat generating element is preferably a store of electric energy. The invention also relates to a vehicle, preferably an electric vehicle, comprising such an enclosure. [Background technology]

[0002] During operation, battery modules, such as those used in electric vehicles, can heat up and therefore are cooled to extend their life and improve their efficiency.

[0003] In a battery module, the battery cells are placed and fixed in what are known as cell holders, which can be made of plastic, for example. Under the cells, cooling is usually achieved by plate-like heat exchangers, conventionally made of aluminum. Thus, there is usually an upper part, where the cells are fixed in the cell holder, and a lower part, where the cooling is achieved. The heat transfer area is finally plate-like. The individual parts are clamped and integrated into the battery housing.

[0004] In one variation, the cell holder and the housing are made as a single unit, and cooling is performed underneath using an aluminum plate heat exchanger as in the conventional method.

[0005] Patent Document 1 relates to a battery module having a number of electrically connected battery cells, the temperature of each of which is controlled by a heat transfer fluid. A flow path system through which the heat transfer fluid flows runs between the battery cells, and the flow path system is separated from the battery cells by a degassing system.

[0006] Patent Document 2 discloses an enclosure for housing a plurality of battery cells, particularly lithium-ion battery cells, in which the enclosure, particularly a plastic enclosure, includes a cooling device having inlet and outlet positions for an air flow for cooling the battery cells. The enclosure is constructed as an integral part with the cooling device integrated therein, which additionally includes spacers for arranging all the battery cells so that they are housed with air-conducting intermediate spaces between the battery cells. As a result, the air flow is provided by the air flow paths between the battery cells. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Application Publication No. 102014201165 [Patent Document 2] German Patent Application Publication No. 102014221684 Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a housing for a heating element that is easy to manufacture. [Means for solving the problem]

[0009] According to the invention, this object is achieved by means of a housing according to claim 1. The invention likewise provides a method according to claim 12 and a system according to claim 13. Advantageous further developments are given in the dependent claims. These can be combined with one another in any way, unless the context clearly indicates otherwise. The embodiments described in relation to the housing are also applicable to the method and the system.

[0010] The housing for at least one heat generating element comprises a housing wall, a holder that is joined to the housing wall and that houses at least one heat generating element, and a cooling body that is arranged on the side of the housing wall opposite the holder and is joined to the housing wall. The housing wall, the holder and the cooling body are present together as an integral part. The cooling body has at least one flow passage for a coolant. As a result, the cooling body has a structure molded on the housing wall. For the purposes of the present invention, "arranged on the opposite side of the housing wall" means that the holder is arranged inside the housing, while the cooling body is arranged outside the housing. At least the material of the cooling body comprises a first thermoplastic polymer having a thermal conductivity of 0.2 W / (m K) or more, determined according to ASTM E1461-01. When speaking of "thermal conductivity" in this application, we always mean through-plane thermal conductivity. For the purposes of the present invention, "polymer" is synonymous with "polymer composition". Thus, at least one subregion of the cooling body consists of a thermoplastic polymer composition having a thermal conductivity, determined according to ASTM E1461-01, of at least 0.2 W / (m K). Preferably, the entire cooling body consists of this first thermoplastic polymer composition.

[0011] Since the housing wall, the holder, and the cooling body are integrally present together, the housing can be easily manufactured by injection molding. The thermal conductivity of the first thermoplastic polymer composition is preferably in the range of 0.2 W / (m K) to 20 W / (m K), more preferably in the range of 0.3 W / (m K) to 16 W / (m K), and particularly preferably in the range of 0.4 W / (m K) to 8 W / (m K).

[0012] The integral housing elements can be made of the same material, but it is also possible to use different materials which are then bonded together by substance-to-substance bonding to obtain an integral housing.To remove heat, at least the material of the cooling body comprises the thermally conductive thermoplastic polymer composition described above.

[0013] The method for manufacturing the housing according to the invention comprises the steps of producing the housing wall, the holder and the cooling body as an integral part by an injection molding process, again using different materials or the same material overall (first thermoplastic polymer composition).

[0014] In terms of manufacturing, all relevant parts can preferably be manufactured from only two shots or even one shot, which simplifies assembly and manufacturing of the module.

[0015] A system comprises a housing according to the invention and a heating element housed in the holder of the housing, the heating element being preferably an electrochemical store of electrical energy or an electrochemical source of electrical energy, particularly suitable stores are supercapacitors / ultracapacitors or rechargeable batteries such as rechargeable lithium polymer batteries, particularly suitable electrochemical sources are fuel cells such as polymer electrolyte fuel cells and direct methanol fuel cells.

[0016] In one embodiment, the polymer of the first thermoplastic polymer composition is selected from polycarbonate, polyamide, acrylonitrile-butadiene-styrene copolymer, polyphenylene sulfide, polypropylene, or a mixture of at least two of these polymers.

[0017] All elements involved in the heat transfer are preferably made of polycarbonate-based materials. This allows a significant increase in the heat transfer surface to be achieved compared to conventional cooling. The use of similar materials is associated with similar thermal expansion coefficients at the joints. This allows a direct contact between the materials, which reduces the heat transfer resistance compared to the known prior art. With regard to long-term stability, the dimensional precision of polycarbonate is also advantageous.

[0018] Preferred polycarbonates are aromatic polycarbonates, polycarbonates with multiple structural units derived from aromatic alcohols, polyester carbonates, and blends containing these polycarbonates as the main component. The polycarbonates preferably have a weight average molecular weight Mw of 22000 g / mol to 29000 g / mol, where the Mw value is determined by gel permeation chromatography using dichloromethane as eluent and calibrated against bisphenol A polycarbonate standards. The polycarbonates are preferably prepared by reaction of bisphenol compounds with carbonate compounds, in particular phosgene, or by the melt transesterification process using diphenyl carbonate or dimethyl carbonate.

[0019] Particular preference is given here to homopolycarbonates based on bisphenol A and to copolycarbonates based on the monomers bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, for example Apec® from Covestro Deutschland AG.

[0020] Preferred polyamides are PA-6,1, PA-6,T, PA-6,6, PA-6,6 / 6T, PA-6,6 / 6,T / 6,1 copolyamide, PA-6,T / 2-MPMDT copolyamide, PA-9,T, PA-4,6, and mixtures or copolyamides thereof.

[0021] In a further embodiment, the first thermoplastic polymer composition has a melt volume rate (MVR) determined according to ISO 1133-1:2012-03 (300° C., 1.2 kg) of 8 cm 3 / (10 minutes)~20cm 3 / (10 min). This MVR is 15 cm 3 / (10 minutes)~20cm 3 / (10 min) is preferred.

[0022] In further embodiments, the first thermoplastic polymer composition contains a filler selected from the group consisting of aluminum oxide, boron nitride, silicon oxide, kaolin, talc, or a mixture of at least two of these fillers. Such fillers serve to increase the thermal conductivity of the polymer composition. Naturally, the first thermoplastic polymer composition can contain further additives such as stabilizers, flow improvers, mold release agents, UV absorbers, flame retardants, etc. Such polymers containing additives can also be considered as a whole as the "first thermoplastic polymer". That is, there is not necessarily an artificial distinction between the polymer and the additive, and "polymer" and "polymer composition" have the same meaning in this specification. Preferred combinations are polycarbonate and boron nitride, polycarbonate and kaolin, or polycarbonate and talc.

[0023] The boron nitride used may be in the form of cubic boron nitride, hexagonal boron nitride, amorphous boron nitride, partially crystalline boron nitride, turbostratic boron nitride, wurtzite boron nitride, rhombohedral boron nitride and / or further allotropic forms, but is preferably in the hexagonal form.

[0024] The agglomeration particle size (D(0.5) value) of the above-mentioned thermally conductive fillers, determined by laser light scattering, is preferably 1 μm to 100 μm, preferably 3 μm to 60 μm, particularly preferably 5 μm to 30 μm. In laser light scattering, the particle size distribution is determined by measuring the angular dependence of the intensity of the scattered light of a laser beam passing through a dispersed particle sample. In this specification, the particle size distribution is calculated using the Mie theory of light scattering. The D(0.5) value means that 50% by volume of all particles present in the material under examination are smaller than the indicated value.

[0025] If the housing according to the invention is to be damaged by external influences during use, for example as a housing for a rechargeable battery in an electric vehicle, a very low conductivity of the material increases safety. If the housing is broken or deformed, the conductive elements of the housing may short-circuit the rechargeable battery. Therefore, in a further embodiment, the first thermoplastic polymer composition does not contain a conductive filler. Fillers to be avoided are, in particular, carbon black, graphene, fullerenes, and carbon nanotubes.

[0026] In a further embodiment, the first thermoplastic polymer composition has an elastic modulus, determined according to ISO 527-1 / -2, of 2000 MPa to 3500 MPa (preferably 2500 MPa to 3000 MPa) and / or an Izod impact toughness, determined according to ISO 180 / A at 23° C., of 5 kJ / m 2 More than 60kJ / m 2 Less than 10 kJ / m 2 More than 50kJ / m 2 Less than or equal to 20 kJ / m 2 More than 40kJ / m 2 (see below). Polycarbonates with such mechanical properties are particularly advantageous under impact or shock stresses. When subjected to temporary stress peaks, the material does not suddenly degrade in a brittle manner, but rather plastically. This contributes to the structural integrity of the element after excessive stressing. In contrast to materials that behave brittle and degrade by fracture, tough polycarbonates simply deform.

[0027] The invention will now be further illustrated with the aid of the accompanying drawings, in which: [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 illustrates a system according to the present invention. [Diagram 2] FIG. 2 shows a further system according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Figure 1 shows a schematic representation of a system according to the invention with a housing according to the invention housing a heating element 100, for example a rechargeable battery, in a corresponding holder 300. In the lower part of Figure 1 the system is shown in plan view, in the upper part of Figure 1 a cross-section along the line DD drawn in the lower view.

[0030] The housing comprises a housing wall 200, a number of holders 300 and a cooling body 400 as an integral part. The holder 300 secures the heating element 100 in place by surrounding it at its upper and lower regions. The cooling body 400 is located on the side of the housing wall 200 opposite the holder 300, in this case on the underside of the housing. Due to the integral nature, it is equivalent to design the holder 300 to penetrate the housing wall 200 and the housing wall 200 to penetrate the cooling body 400 in selected regions.

[0031] The cooling body 400 has at least one coolant channel 500. a) At least one coolant channel 500 is preferably a channel open to the environment and the coolant is air. This is shown in FIG. 1. The side walls of the channel 500 can thus also be described as cooling fins. Alternatively, b) At least one channel 500 is a closed channel and the coolant is a liquid. For example, water cooling can be achieved in this way.

[0032] In a further embodiment shown in Fig. 2, the cooling body 400 is in two parts and has a sub-region made of a first thermoplastic composition and a sub-region made of a second thermoplastic composition, the sub-region made of the first thermoplastic composition having a flat side facing away from the holder 300, said flat side being joined by a material bond to the region made of the second thermoplastic composition 600.

[0033] In a further embodiment, the material of the housing comprises 90% by weight or more of said first thermoplastic polymer, based on the total weight of the housing. Fillers and other polymer additives that are or have been incorporated into the polymer formulation are included in this weight ratio of the polymer ("polymer composition"). This weight ratio is preferably 95% by weight or more, more preferably 99% by weight or more, based on the total weight of the housing. Thus, the housing can be characterized as a "one-component housing". The use of only one material allows for a reduction in manufacturing steps.

[0034] In a further embodiment, the material of the enclosure further comprises a second thermoplastic polymer composition different from the first thermoplastic polymer composition and present in areas of the enclosure where the first thermoplastic polymer composition is absent. What has been said with respect to the first polymer composition also applies in principle to the second thermoplastic polymer composition. The polymer of the second thermoplastic polymer composition is preferably the same as the polymer of the first thermoplastic polymer composition, but with a reduced amount of thermally conductive filler or without it. In such "two-component enclosures", the manufacturing requirements can usually be met by using thermoplastics that flow differently in the injection molding process in places on the enclosure where good thermal conductivity is less important. The first thermoplastic polymer composition and the second thermoplastic polymer composition form inter-material bonds together at their interface.

[0035] In a further embodiment, the polymer of the second thermoplastic polymer composition is chosen from among polycarbonate, polyamide, acrylonitrile-butadiene-styrene copolymer, polyphenylene sulfide, polypropylene, or a mixture of at least two of these polymers. To avoid repetition, reference may be made to what has been said above with respect to the first polymer composition.

[0036] In a further embodiment, the second thermoplastic polymer composition contains a flame retardant. Suitable flame retardants are in particular phosphates such as BDP (bisphenol A bis(diphenyl phosphate)). Further suitable flame retardants are phosphazenes such as cyclic and linear phosphazenes of formula (I) and formula (II): [ka] (In the formula, R 1 , R 2 are the same or different and each is alkyl, cycloalkyl, aryl, or alkylaryl; R 3 , R 4 are the same or different and each is alkyl, cycloalkyl, aryl, or alkylaryl; R 5 is -N=P(OR 3 ) 3 , -N=P(OR 4 ) 3 , -N=P(O)OR 3 , or -N=P(O)OR 4 and R 6 is -N=P(OR 3 ) 4 , -N=P(OR 4 ) 4 , -N=P(O)(OR 3 ) 2 , or -N=P(O)(OR 4 ) 2 where a is an integer ranging from 3 to 25, and b is an integer ranging from 3 to 10,000.

[0037] Among the cyclic phosphazenes of formula (I) used according to the present invention, it is preferred to use those in which a in formula (I) is an integer in the range of 3-8, particularly preferably an integer in the range of 3-5.

[0038] Among the chain phosphazenes of formula (II) used according to the present invention, it is preferred to use those in which b is an integer in the range of 3-1000, particularly preferably in the range of 3-100, and particularly preferably in the range of 3-25.

[0039] It is particularly preferred to use cyclic phenoxyphosphazenes such as those available from Fushimi Pharmaceutical Co., Ltd., Kagawa, Japan, under the trade name Rabitle™ FP110 (CAS number 1203646-63-2), or, when a is 3, 2,2,4,4,6,6-hexahydro-2,2,4,4,6,6-hexaphenoxytriazatriphosphorine (CAS number 1184-10-7).

Claims

1. An enclosure for at least one heating element (100), comprising: An enclosure wall (200); a holder (300) attached to the housing wall (200) and housing the at least one heating element (100); A cooling body (400) disposed on a side surface of the housing wall (200) and joined to the housing wall (200); Equipped with Here, the holder (300) is disposed inside the housing, while the cooling body (400) is disposed outside the housing; The enclosure wall (200), the holder (300) and the cooling body (400) are present together as an integral part, characterized in that the cooling body (400) has at least one flow channel (500) for a coolant, and at least a sub-area of ​​the cooling body (400) consists of a first thermoplastic polymer composition having a thermal conductivity, determined according to ASTM E1461-01, of 0.2 W / (m K) or more.

2. 2. The housing of claim 1, wherein the first thermoplastic polymer composition comprises a polymer selected from the group consisting of polycarbonate, polyamide, ABS, PPS, PP, or a mixture of at least two of these polymers.

3. The first thermoplastic polymer composition has a melt volume rate (MVR) of 8 cm as determined in accordance with ISO 1133-1:2012-03 (300° C., 1.2 kg). ３ / (10 minutes) ~ 20cm ３ 3. The housing of claim 2, comprising a polycarbonate having a viscosity of 100:

1.

4. 4. The housing according to claim 1, wherein the first thermoplastic polymer composition contains a filler selected from the group consisting of aluminum oxide, boron nitride, silicon oxide, kaolin, talc, or a mixture of at least two of these fillers.

5. The first thermoplastic polymer composition has an elastic modulus, determined according to ISO 527-1 / -2, of 2000 MPa to 3500 MPa and / or an Izod impact toughness, determined according to ISO 180 / A at 23° C., of 5 kJ / m ２ More than 60kJ / m ２ The housing according to any one of claims 1 to 4, wherein:

6. The housing according to any one of claims 1 to 5, wherein a) the at least one coolant flow path (500) is a flow path open to the environment and the coolant is air, or b) the at least one coolant flow path (500) is a closed flow path and the coolant is a liquid.

7. 7. The housing according to any one of claims 1 to 6, wherein the material of the housing additionally comprises a second thermoplastic polymer composition different from the first thermoplastic polymer composition and present in areas of the housing where the first thermoplastic polymer composition is not present.

8. 8. The housing of claim 7, wherein the second thermoplastic polymer composition comprises polycarbonate, polyamide, acrylonitrile-butadiene-styrene copolymer, polyphenylene sulfide, polypropylene, or a mixture of at least two of these polymers.

9. A method for manufacturing an enclosure according to any one of claims 1 to 8, comprising the step of producing the enclosure wall (200), the holder (300) and the cooling body (400) as an integral part by an injection molding process.

10. A system comprising an enclosure according to any one of claims 1 to 8 and a heating element housed in the holder (300) of the enclosure.

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