Multi-layer pipeline, immersion type cooling loop and electric vehicle

Abstract

The utility model relates to a multi-layer pipeline, an immersion type cooling loop and an electric automobile. The utility model relates to a multilayer duct (1) for the flow of a dielectric fluid through at least one interior (15) of the multilayer duct (1), in particular in an immersion cooling circuit (2) of at least one immersion-cooled battery (20) or electrical component, characterized in that the multilayer duct (1) comprises at least one duct wall (10), the pipe wall (10) has at least one inner layer (11), at least one intermediate layer (12) and at least one outer layer (13), the at least one inner layer (11) being made of at least one electrically conductive doped polyamide, the at least one intermediate layer (12) being made of at least one polyolefin-based maleic anhydride (MAH)-doped adhesion promoter, and the at least one outer layer (13) being made of at least one polyolefin-based maleic anhydride (MAH)-doped adhesion promoter. And at least one outer layer (13) is made of a mass-balanced polypropylene or of a polypropylene fresh material with a polypropylene return in a proportion greater than 40%.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of multilayer pipe, for making dielectric fluid flow through at least one inner cavity of the multilayer pipe, especially in at least one application of immersion cooling circuit of battery or electrical element of immersion cooling, in addition, it is also related to the immersion cooling circuit of battery with at least one immersion cooling and the electric vehicle with at least one immersion cooling battery. BACKGROUND

[0002] Electric vehicles and hybrid vehicles include batteries or traction batteries for providing power, which provide electrical energy for the electric motors of electric vehicles and hybrid vehicles, which will be converted into mechanical kinetic energy for driving electric vehicles and hybrid vehicles. During the operation of the battery, it is necessary to regulate its temperature so that it is not damaged and reaches the best operating state. It is known to use aluminum cooling plates for such temperature regulation, on which a water / glycol mixture flows. The batteries or traction batteries of electric vehicles have a high energy density, wherein the performance decreases significantly with a slowing down of the chemical reaction at temperatures below 0°C. At temperatures above 30°C, the degree of aging of the battery or its battery modules and battery cells increases significantly, wherein the battery modules are composed of battery cells, and at temperatures above 40°C, the individual battery cells can be damaged. Therefore, in order to achieve the longest possible service life and efficiency of the battery, it is very meaningful to operate the battery within a certain temperature spectrum. In racing cars and supercars, high discharge currents, so-called C-rates, are required because the vehicle has to accelerate. At this time, the indirect cooling of the battery by means of the known aluminum cooling plates is no longer sufficient to dissipate the generated heat. Therefore, it is also known to provide these batteries with so-called immersion cooling.

[0003] In this case, the battery cells are cooled in direct contact with an electrically non-conducting fluid, i.e. a dielectric coolant. One advantage of the immersion cooling of such batteries is that very high charging rates can be achieved, thus shortening the charging time of the battery. In this case, the battery heats up to such an extent that indirect cooling is no longer sufficient. At present, dielectric cooling media are mainly provided in the form of synthetic oils. However, it has been shown that polyolefins such as polypropylene (PP) exhibit an intensified swelling behavior when in direct contact with oil, so that the use in contact with synthetic oils as dielectric coolants is not recommended. Therefore, the suppliers of such dielectric cooling media recommend the use of thermoplastic plastics such as polyamide (PA), polyketone (PK) or polyoxymethylene (POM) for direct media contact.

[0004] In order to counter the increasing cost pressure, especially in the automotive industry, it is necessary to use increasingly cost-effective materials. This affects, inter alia, a pipe, the material costs of which represent a relatively high proportion of the overall pipe length. Polyolefins in the form of, for example, polypropylene are such low-cost thermoplastics, although they have the aforementioned disadvantages when in contact with oil-based dielectric cooling media.

[0005] A further problem is that, in order to avoid the risk of short circuits, the dielectric cooling medium used to flow through the battery cooling plate must never exceed a critical conductivity value. It is therefore necessary to minimize the diffusion of moisture from the environment through the walls of the pipe carrying or flowing through the dielectric cooling medium. Furthermore, the increasing environmental requirements of automobile manufacturers increasingly require the use of sustainable plastics or plastic recyclates. Accordingly, the use of such plastic recyclates is also required when manufacturing the pipe through which the dielectric cooling medium flows.

[0006] When a dielectric fluid, in particular a dielectric cooling medium, flows through an electrically non-conductive pipe or its inner cavity, charge separation occurs, which causes the pipe wall to become negatively charged due to electrostatic charging. When connected to an earth point, such as an earthed vehicle component, a tool or even a person performing maintenance or repair work on the vehicle, a discharge can occur, which can result in damage to the vehicle component or even in an electric shock to the person performing the maintenance or repair work. In order to avoid this, it makes sense to make the inner layer of the pipe or its wall electrically conductive in systems with immersion cooling, such as immersion-cooled batteries of electric vehicles. It is known that thermoplastics used for the pipe wall can be doped with electrically conductive carbon black or carbon nanotubes (CNT). However, there is also the problem that electrically conductively doped plastics are significantly more expensive than standard thermoplastics and also have poorer mechanical properties. In order to solve this problem, multilayer pipes (MLT) with a thin electrically conductive inner layer are used for pipe applications in systems with immersion cooling, such as immersion-cooled batteries. The layer thickness is typically 0.2 to 0.4 mm. Long-chain polyamides, such as PA11 or PA6.12, can be used as the base material for the inner layer.

[0007] It is also known to use PA11 or PA12 as the outer layer of such a multilayer pipe, taking into account the compatibility with the inner layer and the resistance to external media, in particular to zinc chloride, which is produced by the contact of road salt with metal components of the vehicle. The disadvantage of these materials is the relatively high hygroscopicity, so that there is a risk of moisture from the environment being transported into the dielectric medium or fluid, thereby increasing its electrical conductivity. The resulting disadvantage of electrostatic charging has already been mentioned above. A further disadvantage of these materials is the relatively high raw material costs, and the lack of sustainability of these polyamide materials in the case of the use of PA12 or PA6.12. The structure of such a multilayer pipe therefore does not meet the requirements mentioned above. Invention content

[0008] The object of the present application is therefore to provide a multilayer pipe for flowing a dielectric fluid through the inner cavity of the multilayer pipe, which can be used in particular in an immersion cooling circuit of at least one immersion-cooled battery or electrical component, in which case the above-mentioned disadvantages of the prior art are avoided, in which case, in particular, the resistance to external media in the outer layer region of the multilayer pipe, such as in particular zinc chloride, the electrical conductivity of the inner layer, the maximum electrical resistance per meter of pipe length, including the joint, of less than 1 MOhm, and the diffusion of moisture from the environment into the dielectric fluid flowing through the multilayer pipe, such as a dielectric cooling medium, is achieved in the case of at least partial use of sustainable raw materials.

[0009] For the multilayer pipe according to the first aspect of the application, the object of the application is achieved in that the multilayer pipe comprises at least one pipe wall, which has at least one inner layer, at least one intermediate layer and at least one outer layer, wherein the at least one inner layer is made of at least one electrically conductive doped polyamide, the at least one intermediate layer is made of at least one polyolefin-based adhesion promoter doped with maleic anhydride (MAH), and the at least one outer layer is made of polypropylene in mass balance or of polypropylene virgin material with a proportion of more than 40% of polypropylene recyclate. For the immersion cooling circuit of at least one immersion-cooled battery, the object is achieved in that the immersion cooling circuit comprises at least one such multilayer pipe. For the electric vehicle with at least one immersion-cooled battery, the object is achieved in that the electric vehicle comprises at least one immersion cooling circuit for at least one immersion-cooled battery, wherein the at least one immersion cooling circuit comprises at least one such multilayer pipe. Further embodiments of the application are defined in the dependent claims.

[0010] This results in a multilayer pipe suitable for passing a dielectric fluid, such as a dielectric cooling medium, through the pipe, wherein at least one inner layer is made of at least one electrically conductively doped polyamide, the maximum electrical resistance of the pipe length, including the joints, being < 1 M / m. The electrically conductively doped polyamide inner layer of the pipe wall of the multilayer pipe can be used to prevent the dielectric fluid, such as a dielectric cooling medium, flowing through the inner cavity of the multilayer pipe from electrostatically charging the pipe wall. Preferably, PA 11, PA 6.10, PA 4.10, PA 5.10, PA 5.15, PA 5.16 or PA 10.10 is used as the electrically conductively doped polyamide. The respective maximum electrical resistance of all these electrically conductively doped polyamides is < 1 M / m pipe length. It is further advantageous if the electrically conductively doped polyamide of at least one inner layer of the pipe wall of the multilayer pipe is at least partially biobased. This allows for a broad use of sustainable plastics, here referred to as biobased plastics. In particular, at least one of the electrically conductively doped polyamides PA 11, PA 6.10, PA 4.10, PA 5.10, PA 5.15, PA 5.16 or PA 10.10 of at least one inner layer of the pipe wall of the multilayer pipe is at least partially biobased.

[0011] The at least one outer layer of the multilayer pipe is made of a mass-balanced polypropylene or a polypropylene virgin material with more than 40% of the polypropylene regrind. In particular, the mass-balanced polypropylene can contain a proportion of 100% sustainably used raw materials. Alternatively, the polypropylene of the at least one outer layer of the multilayer pipe can use only partially polypropylene regrind and the remainder is produced from polypropylene virgin material, i.e. a mixture of polypropylene regrind and polypropylene virgin material is used. Here, polypropylene virgin material refers to the first production of polypropylene, while polypropylene regrind refers to the reprocessing of polypropylene. The proportion of such polypropylene regrind in the virgin and regrind mixture is more than 40% of the total proportion of polypropylene of the outer layer of the multilayer pipe. This means that at least one outer layer of the pipe wall of the multilayer pipe can consist, for example, of 50% polypropylene virgin material and 50% polypropylene regrind, or only of 40% polypropylene virgin material and 60% polypropylene regrind. The polypropylene as outer layer of the multilayer pipe has excellent resistance to external media, in particular zinc chloride. In addition, the moisture absorption of polypropylene is very low compared to most thermoplastics. The raw material costs of the mass-balanced polypropylene and the mixture made of polypropylene virgin material with more than 40% of the polypropylene regrind are also relatively low. The mechanical properties of the mass-balanced polypropylene are identical to the mechanical properties of the polypropylene virgin material, so that the same mechanical properties as when using a non-mass-balanced polypropylene virgin material for the entire outer layer are obtained without the need for increased layer thicknesses or other compensatory measures.

[0012] By providing at least one intermediate layer made of at least one polyolefin, doped with a maleic anhydride (MAH) adhesion promoter, a very good adhesion of the polypropylene of at least one outer layer of the pipe wall of the multilayer pipe to the electrically conductive doped polyamide of at least one inner layer can be achieved.

[0013] This structure of the pipe wall of the multilayer pipe fulfils both the requirements of the electrically conductive nature of at least one inner layer of the multilayer pipe and the requirements of cost efficiency of the pipe production, low moisture diffusion in the area of the outer layer of the multilayer pipe and the use of sustainable plastics as material of the multilayer pipe.

[0014] The layer thickness of the at least one inner layer of the pipe wall of the multilayer pipe is preferably 0.1 to 0.5 mm, in particular 0.2 to 0.4 mm. This allows to minimize the thickness of the otherwise expensive electrically conductive inner layer material while maintaining the required electrical conductivity of the inner layer for the dissipation of electrical charges. The thickness of the at least one intermediate layer is preferably 0.08 to 0.12 mm, in particular 0.1 mm. Such a layer thickness is sufficient to firmly bond the inner layer to the outer layer. The thickness of the at least one outer layer is preferably also at least 1 mm. This provides the multilayer pipe with sufficient mechanical stability to withstand the pressure and temperature requirements of the multilayer pipe in operation in an electric vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A cross-sectional view of one embodiment of a multilayer pipe according to the present utility model is shown, having an inner layer, an intermediate layer and an outer layer.

[0016] Figure 2 A simplified view of an immersion cooling circuit is shown, comprising several batteries, a multilayer pipe, a heat exchanger for heat exchange with the vehicle coolant circuit, a pump and a filter.

[0017] Figure 3 A top view of an electric or battery electric vehicle according to the present utility model with an immersion cooling circuit according to Figure 2 is shown. DETAILED DESCRIPTION

[0018] In order to explain the present utility model in more detail, one embodiment of the present utility model will be described in more detail below with reference to the drawings.

[0019] Figure 1A three-layer multi-layer pipe 1 with a pipe wall 10 is shown, which has an inner layer 11, an intermediate layer 12 and an outer layer 13. The multi-layer pipe 1 has an inner cavity 15 for the flow of a medium, in particular a dielectric fluid. The outer layer 13 is the thickest layer and is made of mass-balanced polypropylene, in particular polypropylene made using 100% sustainable raw materials, i.e. polypropylene made from 100% sustainable raw materials. In addition, the outer layer 13 can also be made of only polypropylene regrind in a proportion of at least 40% and polypropylene virgin material in a proportion of at most 60%. For example, the layer thickness d 13 of the outer layer 13 can be 1 mm or more. This is sufficient to ensure that the multi-layer pipe 1 has sufficient pressure and temperature stability.

[0020] The inner layer 11 of the pipe wall 10 of the multi-layer pipe 1 is made of an electrically doped polyamide, in particular PA11, PA6.10, PA4.10, PA5.10, PA5.15, PA5.16 or PA10.10. These electrically doped polyamides can be implemented as only partially or completely biobased, i.e. made from renewable raw materials. For example, an electrically conductively doped at least partially biobased PA11 or PA6.10 is used for the inner layer 11. In comparison to the layer thickness d 13 of the outer layer 13, the layer thickness d 11 of the inner layer 11 is very thin, for example can be d 11 = 0.2 to 0.4 mm.

[0021] The intermediate layer 12 of the pipe wall 10 is made of a polyolefin-based adhesion promoter with maleic anhydride (MAH) doping. As a so-called coupling agent or compatibilizer, the maleic anhydride (MAH) can form a very good and stable adhesion between the polypropylene outer layer 13 and the electrically doped polyamide inner layer 11. Without the adhesion promoter, they hardly or cannot adhere to each other, i.e. without the adhesion promoter, the polypropylene of the outer layer 13 and the electrically doped polyamide of the inner layer 11 do not adhere to each other.

[0022] For example, the layer thickness d 12 of the intermediate layer 12 is approximately 0.1 mm. Such a layer thickness is sufficient to achieve a safe adhesion of the outer layer 13 to the inner layer 11.

[0023] As Figure 3 shown, the multi-layer pipe 1 is particularly suitable for the transport of dielectric fluids, which are used, for example, for battery cooling of a battery 20 or traction battery of an electric vehicle 100 or hybrid vehicle. Such a battery 20 consists of a plurality of battery modules 21 which are immersed in the cooling. For this purpose, the battery modules 21 are cooled or temperature-regulated by means of an immersion cooling circuit 2. These are, for example, as Figure 2The three battery modules 21, 21a, 21n are shown here, for example, in which n stands for the number n of battery modules, i.e. for any number of battery modules. The battery modules 21, 21a, 21n or their battery cells are surrounded by a non-conductive, i.e. dielectric fluid, that is in direct contact therewith. The dielectric fluid is supplied to the battery modules 21, 21a, 21n by the multilayer pipe 1 connected to the battery modules 21, 21a, 21n and flows out of the battery modules 21, 21a, 21n again.

[0024] The temperature regulation is carried out by the immersion cooling circuit 2, i.e. not only for cooling the battery 20 or its battery modules 21, 21a, 21n, but also for heating. For the transport of the dielectric fluid in the immersion cooling circuit 2, a pump 22 is provided. Upstream of the pump 22, a filter 23 is connected, for filtering possible suspended matter from the dielectric fluid after it has passed through the battery modules 21, 21a, 21n. For the purpose of an optimized temperature regulation of the battery modules 21, 21a, 21n of the battery 20, the immersion circuit 2 is coupled to the cooling circuit 3 of the electric vehicle 100 or hybrid vehicle or battery electric vehicle (BEV) by means of a heat exchanger 24. The cooling circuit 3 is a subcircuit of the temperature regulation circuit of the thermal management system of the electric vehicle 100. The cooling circuit 3 is coupled to the thermal management module 105 of the thermal management system of the electric vehicle 100 with its flow and return, as Figure 3 is derived. Figure 3 The electric vehicle 100, which is shown in a simplified manner, has a vehicle front region 101, a vehicle rear region 102, a vehicle interior 103, which can accommodate occupants of the electric vehicle 100, and four vehicle wheels 110, 111, 112, 113. As Figure 3 is shown, the main heat transfer 104 can exchange heat with the ambient air and can be arranged in the vehicle front region 101. The main heat transfer 104 serves to absorb heat from the ambient air and to release heat to the ambient air, or to transfer heat from the ambient air to the temperature regulating medium flowing in the cooling circuit 3 and to release heat from the temperature regulating medium to the ambient air. The main heat transfer 104 is a cooling water heat transfer, also referred to as radiator.

[0025] For example, a water-glycol mixture can flow in the cooling circuit 3 of an electric car 100 or a hybrid car. In particular, synthetic oil can flow as dielectric fluid in the immersion cooling circuit 2. Since only the inner layer 11 of the pipe wall 10 of the multilayer pipe 1 made of electrically conductive doped polyamide is in contact with it, and the polyolefin of the outer layer 13, either in the form of mass-balanced polypropylene or in the form of polypropylene made from polypropylene virgin material with a proportion of more than 40% of polypropylene regrind, is not in contact with it, the usual problem of an intensification of the swelling behavior of polypropylene after contact with oil does not occur again. Rather, by providing the outer layer 13 made of mass-balanced polypropylene or polypropylene virgin material with a proportion of more than 40% of polypropylene regrind in combination with the intermediate layer 12 made of a polyolefin-based adhesion promoter doped with maleic anhydride (MAH), at least to a large extent, the transport of moisture from the environment of the multilayer pipe 1, for example in the region of the battery module 21, 21a, 21n, into the dielectric fluid flowing through the multilayer pipe 1 is suppressed. Thus, the risk of an increase in the conductivity of the dielectric fluid can be significantly reduced. Since the maximum electrical resistance of the electrically conductive inner layer 11 is less than 1 M / m pipe length, the connectors (not shown in the figure) connected to the ends of the multilayer pipe 1 are also taken into account, it is also possible to safely dissipate charges through the pipe wall 10 in order to avoid charging of the dielectric fluid flowing through the pipe wall 10 or even electrostatic charging of the pipe wall 10. Figure 2

[0026] In addition to the embodiments described above and shown in the figures for a multilayer pipe for a dielectric fluid, in particular for or used in an immersion cooling circuit for at least one immersion-cooled battery or other electrical component, a number of other embodiments can be provided, including any combination of the features described above, in which the multilayer pipe comprises at least one inner layer consisting of at least one electrically conductive doped polyamide, at least one intermediate layer made of at least one polyolefin-based adhesion promoter doped with maleic anhydride (MAH), and at least one outer layer made of mass-balanced polypropylene or polypropylene virgin material with a proportion of more than 40% of polypropylene regrind.

[0027] Legend of the figures

[0028] 1 multilayer pipe

[0029] 2 immersion cooling circuit

[0030] 3 cooling circuit

[0031] 10 pipe wall

[0032] 11 inner layer

[0033] 12 intermediate layer

[0034] 13 outer layer​

[0035] 15 lumen

[0036] 20 battery / traction battery

[0037] 21 battery module

[0038] 21a battery module

[0039] 21n battery module

[0040] 22 pump

[0041] 23 filter

[0042] 24 heat exchanger

[0043] 100 electric vehicle

[0044] 101 vehicle front region

[0045] 102 vehicle rear

[0046] 103 vehicle interior space

[0047] 104 main heat transferer

[0048] 105 thermal management module

[0049] 110 wheel

[0050] 111 wheel

[0051] 112 wheel

[0052] 113 wheel

[0053] d 11 inner layer 11 layer thickness

[0054] d 12 middle layer 12 layer thickness

[0055] d 13 outer layer 13 layer thickness.

Claims

1. Multilayer pipe (1) for flowing a dielectric fluid through at least one inner lumen (15) of the multilayer pipe (1), characterized in that the multilayer pipe (1) comprises at least one pipe wall (10) having at least one inner layer (11), at least one intermediate layer (12) and at least one outer layer (13), wherein the at least one inner layer (11) is made of at least one electrically conductively doped polyamide, the at least one intermediate layer (12) is made of at least one polyolefin-based, maleic anhydride (MAH) doped adhesion promoter, and the at least one outer layer (13) is made of mass-balanced polypropylene or of polypropylene virgin material with a proportion of polypropylene regrind of more than 40%.

2. Multilayer pipe (1) according to claim 1, characterized in that the multilayer pipe (1) is used in at least one immersion-cooled battery (20) or immersion-cooled circuit (2) of an electrical component.

3. Multilayer pipe (1) according to claim 1, characterized in that the electrically conductively doped polyamide of the at least one inner layer (11) is at least one of polyamide PA11, PA6.10, PA4.10, PA5.10, PA5.15, PA5.16 or PA10.

10.

4. Multilayer pipe (1) according to any one of claims 1 to 3, characterized in that the electrically conductively doped polyamide (11) in the at least one inner layer (11) is at least partially biobased.

5. Multilayer pipe (1) according to any one of claims 1 to 3, characterized in that the layer thickness (d11) of the at least one inner layer (11) is 0.1 to 0.5 mm.

6. Multilayer pipe (1) according to claim 5, characterized in that the layer thickness (d11) of the at least one inner layer (11) is 0.2 to 0.4 mm.

7. The multilayer pipe (1) according to any one of claims 1 to 3, characterized in that the layer thickness (d12) of the at least one intermediate layer (12) is 0.08 to 0.12 mm.

8. Multilayer pipe (1) according to claim 7, characterized in that the layer thickness (d12) of the at least one intermediate layer (12) is 0.1 mm.

9. The multilayer pipe (1) according to any one of claims 1 to 3, characterized in that the layer thickness (d13) of the at least one outer layer (13) is at least 1 mm.

10. Immersion-cooled circuit (2) for at least one immersion-cooled battery (20), characterized in that the at least one immersion-cooled circuit (2) comprises at least one multilayer pipe (1) according to any one of claims 1 to 9.

11. Electric vehicle (100) with at least one immersion-cooled battery (20), characterized in that the electric vehicle (100) comprises at least one immersion-cooled circuit (2) for at least one immersion-cooled battery (20) according to claim 10, wherein the at least one immersion-cooled circuit (2) comprises at least one multilayer pipe (1) according to any one of claims 1 to 9.

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