Application of cooling pipe for electric vehicle

Abstract

The invention relates to the use of a pipe (1) as a pipe section in a cooling circuit of a coolant, the cooling circuit being a component of a battery cooling system of an electric vehicle, the pipe (1) being a multi-layer pipe having an innermost layer (2) in contact with the coolant, the innermost layer (2) has a conductive additive for increasing electrical conductivity.

Description

Technical Field

[0001] The present invention relates to the application of a pipe as a pipe segment in a cooling circulation loop of a coolant, wherein the cooling circulation loop is a component of the battery cooling system of an electric vehicle, wherein the pipe is a multilayer pipe, wherein the pipe has an innermost layer in contact with the coolant. Background Technology

[0002] The use of multi-layered tubes to guide cooling oil for cooling components within motor vehicles with internal combustion engines is known from US 2013 / 0037154 A1. However, a disadvantage is that such devices are only conditionally suitable for cooling the drive batteries of electrically driven motor vehicles (“electric vehicles”), particularly due to the limited cooling applicability of the disclosed tubes. Summary of the Invention

[0003] Therefore, the objective of this invention is to provide a tube that is more suitable for electric vehicles, particularly for cooling electric vehicles—especially the battery or drive battery of an electric vehicle—or is capable of achieving greater cooling power.

[0004] This task is solved by using a pipe as a pipe segment in a cooling circulation loop of a coolant, wherein the cooling circulation loop is a component of the battery cooling system of an electric vehicle, wherein the pipe is a multilayer pipe, wherein the pipe has an innermost layer in contact with the coolant, characterized in that the innermost layer has a conductive additive for improving conductivity.

[0005] This invention is based on the understanding that conventional fluid conduits—such as those disclosed in US 2013 / 0037154 A1—cannot provide the required cooling power. Electric vehicle batteries, or drive batteries, weigh hundreds of kilograms and become very hot, especially during fast charging, thus requiring considerable cooling power. This is particularly relevant when the vehicle is stationary during charging and therefore cannot utilize running air for auxiliary cooling.

[0006] This invention is also based on the understanding that high cooling power primarily depends on a large volumetric flow rate of the coolant. A large volumetric flow rate can be achieved by increasing the pump power while keeping the pipe inner diameter constant, or by increasing the pipe inner diameter while keeping the pump power constant—or a combination of both. This invention is particularly based on the understanding that a larger pipe inner diameter is more economically advantageous when considering the entire vehicle and not just the fluid piping.

[0007] It has been found that large volumetric flow rates or large inner diameters, and the resulting relatively large frictional area between the coolant and the innermost layer, can lead to relatively large electrostatic charging. This charging is particularly critical when cooling batteries or drive batteries, thus exposing battery cooling systems to a relatively high risk of fire or ignition. For electric vehicles, there is the additional problem of fires being difficult to extinguish.

[0008] The continuous electrostatic charging that occurs during fluid or coolant flow is counteracted by continuous electrostatic discharge through conductive additives in the innermost layer. This makes skipped discharges or electric shocks significantly less likely or completely avoidable. This effect is particularly advantageous when combined with immersion cooling, allowing for continuous and targeted discharge from the coolant and from the battery. Consequently, the probability of fire in electric vehicles with large-diameter cooling pipes is significantly reduced.

[0009] The present invention is also based on the understanding that the added conductive additive according to the invention does not dissolve in the inner layer, but forms a phase in the form of fine particles in the innermost layer. These particles, or the interfaces of these particles, are ultimately sites with a high probability of crack formation, thereby weakening the innermost layer to some extent.

[0010] However, it has been found that the higher crack formation probability of the innermost layer is preferable at the cost of increased conductivity. Thus, the outermost tube layers can compensate for the weakness of the innermost layer and also act as a barrier relative to the coolant. The result is a cooling tube that improves cooling power without simultaneously increasing the risk of fire, thereby solving the aforementioned problem.

[0011] The term "electric vehicle" preferably refers to a vehicle that is purely electric or partially electric driven, wherein at least one electric motor is used for propulsion. Particularly preferred is that the electric vehicle is a battery electric vehicle, which obtains part or all of its energy for the electric drive motor from a battery or drive battery. The term "battery" particularly preferably refers to a drive battery used in or within an electric vehicle. The drive battery of an electric vehicle preferably comprises a housing. Advantageously, the drive battery has a large number of electrically interconnected individual cells. This large number of individual cells is suitably surrounded by the housing. The large number of individual cells can be divided into multiple battery blocks, wherein each battery block can have multiple individual cells. The individual cells can be grouped into battery blocks electrically and / or mechanically (positioning, arrangement).

[0012] The battery cooling system suitably includes a cooling circulation loop and / or electrical and / or electronic and / or software components. This cooling circulation loop is preferably an integral part of a refrigeration unit. The cooling circulation loop preferably includes fluid guiding components (e.g., heat exchangers, compressors, throttling devices) and / or fluid conduits for the refrigeration unit. This refrigeration unit is particularly a compression refrigeration unit. The cooling circulation loop of a compression refrigeration unit suitably includes multiple fluid guiding components, particularly a compressor or air compressor and / or a heat exchanger or evaporator on the heat source side and / or a heat exchanger or condenser or compressor on the heat sink side and / or a throttling device. Suitably, the heat exchanger or evaporator on the heat source side exchanges heat with the battery or drive battery. Advantageously, the heat exchanger / condenser / compressor on the heat sink side is cooled by air cooling. This air cooling may include, for example, a fan and a metal heat-conducting element.

[0013] The pipe is preferably formed in a pipe section between two or more fluid guiding components in a cooling circulation loop. The pipe suitably has a central axis or longitudinal axis. This central axis or longitudinal axis suitably defines the axial, radial, and circumferential directions. Preferably, the pipe is constructed rotationally symmetrically with respect to the central axis or longitudinal axis in at least one axial segment.

[0014] Preferably, the conductive additive comprises carbon, such as graphite or conductive carbon black. Advantageously, the innermost layer comprises a plastic in which the conductive additive for improving conductivity is incorporated. Very preferably, the conductive additive is mixed beneath the plastic of the innermost layer. The conductive additive is preferably not plastic. Very preferably, the material of the innermost layer has a resistivity of up to 100, 50, 20, 10, or 5 Ωm. This ensures a sufficiently strong discharge tendency, allowing the innermost layer to be designed to be relatively thin.

[0015] Very particularly preferred is that the battery cooling system is an immersion cooling system. The term "immersion cooling system" preferably refers to a cooling system in which the individual cells and / or individual battery blocks of the drive battery are in direct contact with and flushed by a coolant. Preferably, the drive battery includes an inlet for the coolant to enter the interior of the drive battery housing. Suitably, the housing includes an outlet for the coolant. Immersion cooling is particularly distinguished from battery cooling systems that mount plate heat exchangers on the inner or outer side of the housing to the drive battery wall, because in this case, the individual cells or battery blocks are not in direct contact with the coolant. Preferably, the electrical components and / or the inner side of the housing of a drive battery with immersion cooling are designed to be in contact with the coolant. Compared to conventional battery cooling systems that have, for example, cooling plates as heat exchanger elements of the drive battery, immersion cooling systems enable very rapid heat dissipation, especially the dissipation of heat generated during charging. However, because the flushed surface is much larger, a significantly larger volumetric flow rate is also required, thus necessitating pipes with a larger inner diameter within the cooling circulation loop.

[0016] Preferably, the coolant is electrically insulating or dielectric. Preferably, the coolant comprises at least one oil, wherein the content of the at least one oil or multiple oils is 50, 70, 90, or 95% by weight or more of the coolant.

[0017] Preferably, the tube comprises at least one type of plastic. Advantageously, the tube comprises at least 30, 50, 70, 90, or 95% by weight of plastic. This makes it possible to manufacture the tube economically by extrusion.

[0018] According to a very particularly preferred embodiment, the tube comprises at least one carrier layer, wherein the at least one carrier layer preferably comprises a plastic. The plastic of the at least one carrier layer is preferably a polyamide—particularly PA6—and / or a fluoropolymer, particularly ethylene tetrafluoroethylene (ETFE). Both PA6 and ETFE provide good barrier properties against coolant or cooling oil. This relates to the increased probability of cracking in the innermost layer. ETFE is superior to other fluoropolymers due to its properties as a thermoplastic. Polyamides are superior to fluoropolymers in the carrier layer because they are mechanically stronger. Preferably, the carrier layer surrounds the innermost layer. Advantageously, the carrier layer adheres to the innermost layer. The at least one carrier layer or these carrier layers advantageously have a layer thickness or total layer thickness of at least 0.4, 0.6, or 0.7 mm. Very preferably, the carrier layer comprises the same plastic as the innermost layer. When the carrier layer has the same plastic as the innermost layer, the carrier layer adheres very well to the innermost layer. The at least one carrier layer or these carrier layers advantageously have a layer thickness or total layer thickness of up to 2.0, 1.7, or 1.5 mm. The carrier layer or these carrier layers preferably do not contain additives for improving conductivity.

[0019] Particularly advantageous is that the innermost layer of the tube is made of polyamide or fluoropolymer. This allows the conductive additive in the innermost layer to bond well in both the polyamide and fluoropolymer. As a result, the probability of leaching and cracking are minimized. For polyamide, the amide groups generate dipoles, forming hydrogen bonds with the conductive additive, thereby effectively binding the additive particles into the polyamide matrix. Fluoropolymers are very stable materials, thus inherently protecting the conductive additive from leaching. The polyamide of the innermost layer is preferably PA6 or PA9T. The fluoropolymer of the innermost layer is preferably ETFE.

[0020] Advantageously, the tube includes an outer layer. This ensures excellent external mechanical protection as well as good chemical protection against external weather effects and other influences from the vehicle's interior. In particular, the outer layer ensures that the carrier layer no longer needs to perform the function of external shielding, thus allowing the carrier layer to be limited to mechanical support and barrier functions. This outer layer can be the outermost layer of the tube. According to one embodiment, the outer layer can be surrounded by another layer. According to a preferred embodiment, the outer layer comprises polyamide, preferably PA12 and / or PA6.12. Advantageously, the thickness of the outer layer is at least 0.10, 0.15, or 0.20 mm. Suitably, the thickness of the outer layer is at most 0.9, 0.7, 0.5, or 0.4 mm.

[0021] Preferably, the tube has an adhesive layer. This adhesive layer advantageously surrounds the carrier layer and preferably abuts against it. Suitably, an outer layer surrounds the adhesive layer. Preferably, the outer layer abuts against the adhesive layer. The adhesive layer may have a thickness of up to 0.3, 0.25, 0.20, or 0.15 mm. The adhesive layer preferably comprises a plastic. The plastic of the adhesive layer may be a blend. The blend may have a carrier layer of plastic and an outer layer of plastic. The adhesive layer may include an adhesion modifier for improving the adhesion of the plastic to the adhesive layer, such as maleic anhydride.

[0022] According to a preferred embodiment, the innermost layer has a thickness of up to 0.5, 0.4, or 0.3 mm. This ensures that only the smallest possible portion of the tube wall is loaded or weakened by the additive particles, thereby achieving relatively high overall tube stability. The thickness of the innermost layer is advantageously at least 0.05, 0.06, 0.07, or 0.08 mm. This, considering the additive particles, allows for sufficient continuous wetting of the inside of the tube with the innermost layer.

[0023] Advantageously, the pipe wall thickness is at least 0.5, 0.7, or 0.9 mm. This ensures sufficient stability of the pipe or pipe wall even in the event of an accident, despite the relatively large inner diameter of the pipe due to the large volumetric flow rate. This offsets the instability disadvantages of large pipes or large inner diameter pipes. The pipe wall thickness is preferably up to 3.0, 2.5, or 2.0 mm.

[0024] Advantageously, the pipe has an inner diameter of at least 10, 12, 13, or 14 mm. This ensures sufficient volumetric flow rate without requiring a larger pump or compressor. Suitably, the inner diameter, or net inner diameter, of the pipe is at most 50, 40, 35, or 30 mm. The term "inner diameter" preferably refers to the net inner diameter. For bellows, the inner diameter refers to the inner diameter formed by passing through half a circumference of a corrugation (= net inner diameter).

[0025] According to one embodiment, the pipe—suitably in the axial direction—comprises at least one corrugated section. This makes the pipe more flexible overall, and thus—particularly in the event of an accident—significantly more resistant. Providing a corrugated section in this way offsets the greater instability or risk of breakage and cracking that would result from a relatively large inner diameter. The term "corrugated section" preferably refers to a varying inner and / or outer diameter or a varying inner and / or outer profile observed in a longitudinal section along at least one axial segment of the pipe, wherein preferably, this variation in the inner and / or outer diameter or inner and / or outer profile forms a repeating pattern or repeating design. Suitably, the profile of the repeating pattern is serrated, rectangular wavy, and / or wavy. Very particularly preferred is that the inner and / or outer wall profiles of the troughs are constructed to be curved. The inner and / or outer wall profiles of the crests may be constructed parallel to the longitudinal axis of the pipe.

[0026] Viewed in longitudinal section, the repeating pattern preferably has an axial length (wavelength) of up to 50, 20, or 10 mm. The wavelength of the repeating pattern is advantageously at least 1.0, 1.5, or 2.0 mm. Preferably, the corrugated section comprises multiple repeating pattern cycles. The corrugated section may have a length of at least 50, 75, or 100 mm. According to a highly preferred embodiment, the corrugated section corresponds to at least 30%, 50%, 70%, 90%, 95%, or 97% of the axial length of the pipe. The amplitude of the repeating pattern is preferably at least 0.5, 0.7, or 0.8 mm. The amplitude of the repeating pattern is preferably up to 3.0, 2.0, or 1.5 mm. According to one embodiment, the repeating pattern forms a closed loop in one revolution. According to one embodiment, the repeating pattern is generated by a helical orientation such that the repeating pattern does not form a closed loop in a complete revolution.

[0027] According to one embodiment, the pipe is a smooth pipe along its entire length, or the pipe has no corrugated sections along its entire length. The term "smooth pipe" preferably refers to a pipe with a constant inner diameter and / or a constant outer diameter along its entire length.

[0028] Advantageously, the pipe is a component of a fluid conduit, wherein the fluid conduit has at least one pipe connector, which is preferably constructed as a connecting sleeve. This shifts the complexity of fluid technology from the fluid guiding components to be connected to the fluid conduit. As a result, suppliers can offer simpler connections to complete sets of fittings, thereby ensuring better division of labor and economy overall. Attached Figure Description

[0029] An embodiment of the present invention will now be described in more detail with the aid of two schematic diagrams. The diagrams show:

[0030] Figure 1 A cross-section of the tube according to the invention is shown; and

[0031] Figure 2 Show Figure 1 Longitudinal section of the central tube. Detailed Implementation

[0032] exist Figure 1 An embodiment of a pipe 1 according to the invention is disclosed. This pipe 1, according to the invention, is used as a pipe section in the cooling circulation loop of a cooling system for an electric vehicle. This cooling system preferably cools the drive battery of the electric vehicle. Preferably, the cooling system or battery cooling system is configured as an immersion cooling system or submerged cooling system. The cooling circulation loop of this embodiment suitably includes a plurality of fluid guiding components. As the coolant for the immersion cooling system, a dielectric coolant is preferred, and cooling oil is particularly preferred.

[0033] The fluid guiding components preferably include a compressor, evaporator, condenser, and / or throttling device. Suitably, the evaporator exchanges heat with a battery or drive battery. Advantageously, the condenser is cooled by air cooling. This air cooling may include, for example, a fan and a metal heat-conducting element. The pipe is preferably a section of pipe arranged in a fluid-technical manner between at least two fluid guiding components. Due to T-pipe connectors, pipe 1 may also be located in a fluid-technical manner between three or more fluid guiding components.

[0034] The battery cooling system or immersion cooling system is preferably a component of the fast charging system for the electric vehicle. Suitably, the charging curve of the fast charging system is configured such that the charging power at a 25% charge state is not less than 10 kW, 15 kW, 20 kW, 30 kW, or 40 kW. The term "charging curve" preferably refers to the maximum possible charging power plotted with respect to the charge state under ideal charging conditions (temperature, electrical infrastructure, etc.).

[0035] In this embodiment, pipe 1 comprises a total of four layers: 2, 3, 4, and 5. (See attached diagram.) Figure 1 The innermost layer 2 preferably comprises PA6 as the main component (relative maximum weight percentage) and may have a layer thickness of 0.15 mm. The innermost layer 2 particularly preferably has a conductive additive for improving conductivity. This conductive additive preferably comprises conductive carbon black. The material of the innermost layer 2 advantageously has a resistivity of 1 Ωm.

[0036] According to a preferred aspect of the invention, the tube 1 has a carrier layer 3. The carrier layer 3 advantageously comprises the same plastic as the innermost layer 2, thus in this embodiment, the carrier layer 3 preferably comprises PA6 as the main component. Preferably, the carrier layer 3 does not contain additives for improving conductivity. This achieves good adhesion of the carrier layer 3 to the innermost layer 2, while the absence of conductive carbon black and preferably no particles in the carrier layer 3 ensures particularly high tensile strength. In this embodiment, the thickness of the carrier layer 3 is 0.95 mm.

[0037] In this embodiment, the tube 1 advantageously has an outer layer 5. The outer layer 5 preferably comprises a plastic, more preferably a polyamide, and particularly preferably PA12 or PA6.12. The thickness of the outer layer 5 can be, for example, 0.3 mm. Preferably, the tube 1 includes an adhesive layer 4 between the carrier layer 3 and the outer layer 5. The adhesive layer 4 can have a thickness of 0.1 mm. In this embodiment, the adhesive layer 4 preferably comprises a PA6 / 12 copolymer, thus adhering very well to the PA6 carrier layer 3 and the outer layer 5.

[0038] In this embodiment, the carrier layer 3 surrounds the innermost layer 2, wherein the carrier layer 3 preferably abuts against the innermost layer 2. Advantageously, the adhesive layer 4 surrounds the carrier layer 3, wherein the adhesive layer 4 preferably abuts against the carrier layer 3. Preferably, the outer layer 5 surrounds the adhesive layer 4, wherein the outer layer 5 preferably abuts against the adhesive layer 4.

[0039] Figure 2 The dashed line in the diagram represents the axis (central axis or longitudinal axis) of pipe 1. For simplicity, Figure 2 Not shown in the middle Figure 1 The four layers 2, 3, 4, and 5 are described. Pipe 1 preferably includes a corrugated section, wherein in this embodiment, the corrugated section occupies 90% of the axial length of pipe 1. This corrugated section preferably has multiple troughs 6 and crests 7.

[0040] The trough 6 defines the (net) inner diameter ID. The outer side of the crest 7 determines the outer diameter AD. The axial spacing between two crests 7 or two troughs 6 appropriately defines the wavelength WL. A trough 6 and a crest 7 preferably together form a repeating pattern with wavelength WL. Figure 2 The amplitude A preferably corresponds to half of the radial distance between the peaks 7 and troughs 6 on the outer side of the tube 1.

[0041] In this embodiment, the inner diameter ID of tube 1 can be approximately 16 mm. Preferably, the tube wall thickness—preferably measured at the trough 6—is 1.5 mm. In this embodiment, the amplitude A of the wave in the tube wall is 1 mm. As a result, the outer diameter AD of this embodiment is 23 mm. The wavelength WL of the repeating pattern can be 4 mm. Tube 1 of this original embodiment combines high flexibility with a relatively thick and therefore correspondingly robust tube wall, thereby ensuring a particularly high level of safety for tube 1 in the event of an accident. Due to the use of polyamide 6 in the innermost layer 2 and the carrier layer 3, good chemical resistance to coolants, especially cooling oil, is ensured. By adding conductive carbon black, static electricity is reliably and controlledly discharged through the innermost layer 2, thereby protecting the drive battery, in particular, from spontaneous discharge.

[0042] While the outer layer 5 ensures good protection against external influences—especially in the event of an accident—the adhesive layer 4 provides a good bond between the outer layer 5 and the carrier layer 3. The carrier layer 3, in turn, bonds very well to the innermost layer 2 due to its main component being of the same PA6 form, thus forming a very robust and durable laminate. This very robust laminate allows for a correspondingly large inner diameter ID while maintaining high flexibility, thereby enabling high cooling power.

[0043] List of reference numerals in the attached diagram:

[0044] 1 tube

[0045] 2 Innermost layer

[0046] 3 carrier layers

[0047] 4 adhesive layers

[0048] 5 outer layers

[0049] 6 troughs

[0050] 7 peaks

[0051] WL wavelength

[0052] Amplitude

[0053] ID inner diameter

[0054] AD outer diameter.

Claims

1. The application of pipe (1) as a pipe section in the cooling circulation loop of coolant, wherein, The cooling circulation loop is a component of the battery cooling system of an electric vehicle, wherein the tube (1) is a multilayer tube having an innermost layer (2) in contact with the coolant, characterized in that the innermost layer (2) has a conductive additive for improving conductivity.

2. The application according to claim 1, wherein, The battery cooling system is an immersion cooling system.

3. The application according to claim 1 or 2, wherein, The tube (1) includes at least one carrier layer (3), wherein the at least one carrier layer (3) preferably has polyamide and / or fluoropolymer.

4. The application according to any one of claims 1 to 3, wherein, The innermost layer (2) of the tube (1) has polyamide and / or fluoropolymer.

5. The application according to any one of claims 1 to 4, wherein, The tube (1) includes an outer layer (5), wherein the outer layer (5) preferably has polyamide.

6. The application according to any one of claims 1 to 5, wherein, The innermost layer (2) has a maximum thickness of 0.5 mm, 0.4 mm, or 0.3 mm.

7. The application according to any one of claims 1 to 6, wherein, The wall thickness of the tube (1) is at least 0.5 mm, 0.7 mm, or 0.9 mm.

8. The application according to any one of claims 1 to 7, wherein, The tube (1) has an inner diameter (ID) of at least 12 mm, 13 mm or 14 mm.

9. The application according to any one of claims 1 to 8, wherein, The pipe (1) includes at least one corrugated pipe section.

10. The application according to any one of claims 1 to 9, wherein, The pipe is a component of a fluid conduit, wherein the fluid conduit has at least one pipe connector, wherein the pipe connector is preferably configured as a connecting sleeve.

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