Cooling system for busbars
By coating the bus connection area with a gel-like thermally conductive medium and combining it with a passive or active cooling system, the problem of Joule heat dissipation difficulties in high-current applications of the bus is solved, achieving efficient heat transfer and battery module safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AUTO KABEL MANAGEMENT GMBH
- Filing Date
- 2021-03-29
- Publication Date
- 2026-06-19
AI Technical Summary
Busbars generate Joule heat due to ohmic losses in high-current applications, which prevents the heat from being dissipated effectively, especially in the tightly packed housing of batteries or battery modules, where heat dissipation problems exist.
A gel-like thermally conductive medium is coated in the connection area of the busbar and combined with a passive or active cooling system. The thermally conductive medium is in direct contact with the shell wall, and the thermal conductivity is improved by using metal materials. A ribbed cooling body or a cooling medium pipe is set on the outside of the shell for heat transfer.
It effectively dissipates the Joule heat generated by the busbar, protects the conductors from damage, and improves the durability and electrical safety of the busbar.
Smart Images
Figure CN115552695B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a cooling system for busbars, particularly for busbars used as cell connectors or module connectors for batteries, especially in automotive applications. Background Technology
[0002] Busbars are increasingly used in automotive applications. Busbars offer advantages such as good current-carrying capacity and excellent fit into existing structural spaces. They are particularly useful for conductors requiring high current-carrying capacity, typically exceeding 16mm². 2 Preferably up to 250 mm 2 This results in larger conductor cross-sections. Depending on the application, the busbar has a current-carrying capacity of 100A to multiple 100A, which leads to high ohmic losses even when the busbar conductivity is high.
[0003] Ohmic losses cause Joule heating, which needs to be forcibly dissipated to protect the conductor from damage. However, this is disadvantageous because, for necessary electrical safety, the busbar is usually surrounded by an electrical insulator that is also a thermal insulator.
[0004] If Joule heat is dissipated solely by convection, this is particularly problematic when a specific busbar is used within a compact enclosure such as a battery or battery module. Summary of the Invention
[0005] Therefore, the object of the present invention is to improve the durability of the bus when used in high current circuits.
[0006] This objective is achieved through a cooling system.
[0007] The bus according to the invention is formed, for example, of aluminum or an aluminum alloy, or of copper or a copper alloy. The bus typically has a conductor cross-section with angular edges, particularly a square or rectangular conductor cross-section. The bus can be formed as a flat piece and is, for example, cut or stamped from sheet or strip, or extruded from preformed material.
[0008] The application areas of the bus according to the invention are particularly in automotive applications. This is especially applicable for connecting batteries, whether drive batteries, auxiliary batteries, or other batteries in a vehicle. In the context of the invention, a battery can be interconnected battery cells. A single cell, such as a lithium-ion cell, is connected in parallel and / or in series with multiple other cells to form a battery module. Within a battery module, multiple cells are each encapsulated in a common housing. The individual cells can be interconnected via the bus according to the invention.
[0009] The battery according to the invention can also be a battery module. The bus according to the invention can be configured to connect battery modules to each other or to connect battery modules to electrical loads or connecting components. As already mentioned, multiple battery cells are combined into a battery module. Each individual module can be encapsulated in its own housing. Multiple modules can also be encapsulated in their own housings. These modules are interconnected in series and / or parallel. Connections between modules or to other components can be made using the bus according to the invention.
[0010] Furthermore, the bus according to the invention can also be used as a so-called "Energy Backbone®", particularly for the connection between the drive battery and the motor. Such a bus can also be guided, for example, in a housing, such as a cable channel. The cable channel can be specifically designed to improve electrical safety.
[0011] In all of the applications described, the busbar is subjected to high electrical loads during operation. Currents of 100A or greater flow through the busbar. These high currents result in high ohmic losses and, consequently, large Joule heats that must be dissipated.
[0012] According to the invention, the busbar is connected to at least one pole of a battery cell or battery module via a first connection region. In the case of a cell connector, the busbar is connected to a pole of a second battery cell via a second connection region. In the case of a module connector, the busbar is connected to a pole of a second battery module or to an electrical connection component via a second connection region. In this case, the busbar can act as an "energy backbone" and connect via its second connection region to electrical contact areas of, for example, electrical components, electric motors, comfort appliances, etc., in a vehicle.
[0013] The first and second connection areas of the busbar are preferably located at the distal end of the busbar. These connection areas are particularly located on a wide surface of the busbar, which is surrounded by an end edge and two opposing longitudinal edges of the busbar. The busbar is connected to the battery and / or contact area in a conventional manner and method via its connection areas. Here, spiral connections, clamping connections, brazing connections, fusion welding connections, especially ultrasonic welding, friction stir welding, resistance welding, or similar connections are used in particular.
[0014] Between the connection areas, the busbar is at least partially encased in an insulator. The insulator is preferably PE, PVC, or silicone.
[0015] To improve heat dissipation, particularly to enhance heat dissipation relative to pure air convection, a gel-like thermally conductive medium is proposed to be coated directly onto the surface of the busbar on the side facing away from the pole in at least one of the connection regions. "Gel-like" can also refer to an ointment-like substance in the context of this invention. The thermally conductive medium has a higher thermal conductivity than air, allowing Joule heat to dissipate from the busbar. Preferably, the thermally conductive medium is coated such that the received Joule heat can be released into the environment through a surface area larger than the surface area coated on the busbar.
[0016] According to one embodiment, the heat-conducting medium has a viscosity between 25 Pas and 130 Pas.
[0017] According to one embodiment, the heat-conducting medium has a thermal conductivity that is higher than that of air, at least two or three times that of air. Furthermore, a thermal conductivity between 2 W / mK and 12 W / mK is proposed. It has been found that a thermal conductivity of 6 W / mK is particularly advantageous for the application according to the invention, as this is sufficient to adequately dissipate the generated Joule heat.
[0018] Heat dissipation can be passive or active. In passive heat dissipation, the heat transfer medium is connected to the passive heat exchanger. According to one embodiment, the heat transfer medium is in direct contact with the passive heat exchanger. In particular, the heat transfer medium is sandwiched between the busbar and the heat exchanger. For example, it is possible that when assembling the housing, such as a module connector, onto the busbar, the heat transfer medium is coated and immediately followed by sealing the housing, wherein the heat exchanger is pressed into the heat transfer medium by the sealing.
[0019] According to one embodiment, the heat exchanger may be a housing wall or a portion thereof. The housing wall may also be a housing cover.
[0020] According to one embodiment, a battery cell or battery module is encapsulated in a common housing, and at least one housing wall is in direct contact with a heat-conducting medium. The housing or housing wall itself can be used as a passive heat exchanger. The invention proposes that at least one housing wall is in direct contact with the heat-conducting medium in the housing's mounted state. Therefore, it is possible for heat absorbed by the busbar to be output to the housing wall via the heat-conducting medium. The heat can then be released from the housing wall outwards into the environment.
[0021] To improve the thermal conductivity from the shell outwards, it is proposed that the shell be formed of a metallic material in the region where its wall is in direct contact with the heat-conducting medium. The heat-conducting medium itself can be an electrical insulator. The heat-conducting medium then establishes insulation between the busbar connection region and the shell. However, to transfer Joule heat to the outside of the shell, it has proven advantageous that at least one region of the shell in direct contact with the heat-conducting medium be formed of a metallic material. Metallic materials have good thermal conductivity, thus allowing for particularly good transfer of the induced heat energy to the outside of the shell.
[0022] To achieve good convection on the outer side of the shell, ribbed cooling elements are provided on the shell wall in direct contact with the heat transfer medium. Such cooling elements have a structure that has a particularly large surface area in a given volume, thereby allowing a particularly large amount of heat energy to be released into the air through this surface area.
[0023] According to one embodiment, a heat-conducting medium is guided to the outside of the housing through an opening in the housing. The housing may have a notch through which the heat-conducting medium can be guided from the inside to the outside. A large area on the outside of the housing may be coated with the heat-conducting medium, wherein this area is larger than the area where the heat-conducting medium rests against the busbar. In this way, the heat-conducting medium itself can function as a passive coolant. Because the heat-conducting medium is electrically insulating, it electrically seals the housing. Therefore, the heat-conducting medium itself forms a coolant on the outside of the housing.
[0024] According to one embodiment, an active cooling device is proposed. For this purpose, a conduit containing a liquid or gaseous cooling medium is introduced into the housing. Here, the introduction into the housing can be gas-tight and / or liquid-tight, thereby protecting the battery / battery cell installed in the housing from environmental influences. Inside the housing, the conduit passes directly alongside the heat-conducting medium. This means that the conduit, especially its outer circumferential surface, is in direct contact with the heat-conducting medium. The conduit can also be guided through the heat-conducting medium. The cooling medium flowing through the conduit absorbs heat energy from the heat-conducting medium and transports it to the outside of the housing. The cooling medium is circulated within the conduit and guided to an active heat exchanger outside the housing. Heat exchange occurs at the heat exchanger, allowing heat energy to be removed from the housing by means of the cooling medium.
[0025] As already explained, the busbar can be a battery module connector. In this case, the first pole can be a pole of a first battery module having multiple battery cells connected in parallel, and the second pole can be a pole of a second battery module having multiple battery cells connected in parallel.
[0026] It may be necessary to dissipate other heat energy along the busbar's path. For this reason, it is proposed that the busbar have a region between the two connection areas, serving as a connection area and / or a cooling area, in which insulation is removed and a thermally conductive medium is directly coated. The thermally conductive medium and its arrangement within, on, and outside the housing can correspond to the above-described embodiments.
[0027] For electrical insulation purposes, the thermally conductive medium has a temperature of less than 10. -8 Conductivity in S / m. Attached Figure Description
[0028] The invention will now be further described with reference to the accompanying drawings, which illustrate embodiments. The drawings show:
[0029] Figure 1 A bus according to one embodiment is shown;
[0030] Figure 2a b illustrates a cooling system according to one embodiment;
[0031] Figure 3 A top view of the battery casing is shown;
[0032] Figure 4 A cross-section of the battery casing cover according to one embodiment is shown;
[0033] Figure 5 A cross-section of the cover of a battery casing according to one embodiment is shown;
[0034] Figure 6 A schematic diagram of an active cooling system according to one embodiment is shown. Detailed Implementation
[0035] Figure 1 Busbar 2 is shown. Busbar 2 is formed as a flat conductor having a conductive conductor core 2a and an insulating portion 2b surrounding the core.
[0036] As can be seen, bus 2 has a rectangular conductor profile with two opposing wide surfaces, two opposing narrow surfaces, and two opposing end faces. These surfaces preferably extend parallel to each other, wherein the wide and narrow surfaces extend parallel to each other in the longitudinal direction, and the end faces may extend parallel to each other in the transverse direction to the longitudinal direction.
[0037] Bus 2 consists of a conductor core 2a without an insulating portion 2b and a portion of the conductor core 2a surrounded by an insulating portion 2b. The insulator 2b prevents heat dissipation due to convection on the surface of bus 2. This is particularly important when bus 2 is used in high-current applications. In this case, the conductor core 2a has the insulating portion 2b removed from its connection regions 4 and 6, which are located, for example, in the regions of the distal end face of bus 2, and are connected to the battery terminals as shown below.
[0038] Figure 2a A battery 8 with a housing 10 is shown. Inside the housing 10, battery cells 12 are arranged side by side. Each battery cell 12 has a corresponding electrode 14.
[0039] In a cooling system according to the invention, the busbar 2 is connected to one pole 14 of the battery cell 12 via its connection regions 4 and 6, respectively, particularly in a material-fitting manner. In addition to the connection regions 4 and 6, the busbar 2 may also have other regions where the insulator 2b has been removed, such as the central connection region 5 of the busbar 2.
[0040] When busbar 2 conducts current through battery cell 12, high current may occur, and busbar 2 may become hot. To dissipate the generated Joule heat, it is recommended to directly coat the busbar with a thermally conductive medium 16 in the corresponding connection areas 4, 5, and 6. The thermally conductive medium 16 can be in the form of a gel or ointment. At operating temperatures, for example between -10°C and +70°C, the thermally conductive medium 16 has a non-liquid viscosity and is therefore shape-stable.
[0041] The thermally conductive medium 16 is coated on the surfaces of the connecting regions 4, 5, and 6 of the conductor core 2a that are away from the corresponding poles 14. Joule heat can be transferred away from the busbar 2 via the thermally conductive medium 16, and in particular into or out of the housing 10.
[0042] Figure 2b Another embodiment of a battery 8 having a housing 10 is shown. Here, the battery 8 is formed by battery modules 20, each having at least one pole 14. It is also possible, however not shown, that only one pole 14 of the battery module 20 is provided and the bus 2 is led out from the housing 10 and connected, for example, to another electrical conductor.
[0043] The busbar 2 is connected to pole 14 via connection area 6 and also to pole 14 via connection area 4. Alternatively, connection area 4 may be connected to a connector of another electrical device, cable, etc.
[0044] On opposite sides of the conductor core 2a, a thermally conductive medium 16 is coated according to the present invention, on which the conductor core 2a is not connected to the electrode 14 or other electrical components. Figure 2bThe heat-conducting medium 16 is in direct contact with the conductor core 2a on one hand and with the inner wall of the housing 10 on the other. This enables heat transfer from the conductor core 2a to the housing 10.
[0045] Figure 3 A top view of the housing 10, particularly the housing cover, is shown. It can be seen that the housing wall of the housing 10 has different regions, some of which contain thermally conductive material. This thermally conductive material can be, for example, metallic. Specifically, the housing wall can be penetrated by a metal strip 22. The metal strip 22 can extend along the width and / or length of the housing wall of the housing 10. The metal strip 22 is in direct contact with the thermally conductive medium 16 on the inner side of the housing 10, and the thermally conductive medium is in direct contact with the connection areas 4 and 6 of the busbar 2 on the other side.
[0046] The thermally conductive medium 16 is non-conductive and forms an insulator between the electrode 14 and the metal strip 22. Good heat transfer from the inside of the housing 10 to the outside of the housing 10 is particularly possible via the metal strip 22.
[0047] like Figure 4 As shown, the busbar 2 can also be in direct contact with the heat-conducting medium 16 through its connection regions 4 and 6 inside the housing 10. The heat-conducting medium 16 is disposed on the side of the connection regions 4 and 6 away from the electrode 14. The heat-conducting medium 16 is guided through the housing wall of the housing 10, for example, through a notch, as shown in Figure 4 As shown in the diagram. Therefore, the heat-conducting medium 16 is guided from the inside of the housing 10 to the outside of the housing 10.
[0048] On the outer side of the housing 10, the heat-conducting medium 16 can be coated over a large area, particularly on a surface larger than the notch in the housing wall of the housing 10, through which the heat-conducting medium 16 is guided outward. Good heat transfer can be achieved through this enlarged surface.
[0049] Figure 5 Another embodiment is shown, in which the busbar 2 is in direct contact with the electrode 14 and the heat-conducting medium 16 inside the housing 10. A metal strip 22 in the housing wall of the housing 10 connects the heat-conducting medium 16 to the outside of the housing 10. A cooling element 24, such as a ribbed cooling element 24, can be directly mounted on the metal strip 22 on the outside of the housing 10, through which convection can be achieved.
[0050] Alternatively, a so-called "heat pipe" 26 may be guided inside the housing 10. The heat pipe 26 is hermetically guided into the interior of the housing 10. Coolant flows through the heat pipe 26 in a flow direction 28. The flow direction 28 may be influenced by an engine having a heat exchanger 30. At the engine / heat exchanger 30, heat is carried away from the coolant and released into the environment.
[0051] Inside the housing 10, a heat-conducting medium 16 is provided in the connection areas 4 and 6 at the busbar 2. A heat pipe 26 can be guided through the heat-conducting medium 16 or directly adjacent to it within the housing 10. Heat can be transferred from the inside of the housing 10 to the outside via the heat-conducting medium 16 through the coolant in the heat pipe 26, and there it is exchanged with the surrounding environment via the heat exchanger 30.
[0052] The solution shown can be used to efficiently remove Joule heat from a busbar used to connect a battery cell or battery module.
[0053] Explanation of reference numerals in the attached figures
[0054] 2 busbars
[0055] 2a conductor core
[0056] 2b Insulator
[0057] 4, 5, and 6 connecting areas
[0058] 8 batteries
[0059] 10 housing
[0060] 12 battery cells
[0061] 14 battery poles
[0062] 16 thermal conductive medium
[0063] 20 battery modules
[0064] 22 metal strips
[0065] 24 cooling body
[0066] 26 heat pipes
[0067] 28 Flow direction
[0068] 30 Engine / Heat Exchanger
Claims
1. A cooling system for a busbar, comprising: Bus, the bus having The first connection region for the pole of the first battery The second connection area is used for connecting electrical connectors. The insulating portion covering the busbar between the connection areas, wherein The busbar has no insulation in at least two connection areas. in, A gel-like thermally conductive medium is coated directly onto the surface of the busbar on the side of at least one of the connection regions facing away from the pole. Its features are, The heat-conducting medium is guided to the outside of the housing through the housing opening, and The busbar has a cooling zone between the two connection areas, wherein the insulation is removed in the cooling zone and the thermally conductive medium is directly coated onto the cooling zone.
2. The cooling system according to claim 1, Its features are, The heat-conducting medium has a viscosity between 1*10^6 mPas and 1*10^12 mPas.
3. The cooling system according to claim 1 or 2, Its features are, The thermally conductive medium has a thermal conductivity between 5 W / mK and 12 W / mK.
4. The cooling system according to claim 1, Its features are, The heat-conducting medium is in direct contact with the passive heat exchanger.
5. The cooling system according to claim 1, Its features are, The battery is encapsulated in a common housing and at least one housing wall is in direct contact with the thermally conductive medium.
6. The cooling system according to claim 5, Its features are, The housing is formed of a metallic material in the area where its walls are in direct contact with the heat-conducting medium.
7. The cooling system according to claim 5 or 6, Its features are, A ribbed cooling element is provided on the shell wall that is in direct contact with the heat transfer medium.
8. The cooling system according to claim 5, Its features are, A pipe containing a liquid or gaseous cooling medium is introduced into the housing, the pipe is guided directly through the heat transfer medium within the housing, and the pipe is guided outside the housing to an active heat exchanger.
9. The cooling system according to claim 1, Its features are, The first electrode is the electrode of a first battery module having multiple battery cells connected in parallel, and the second electrode is the electrode of a second battery module having multiple battery cells connected in parallel.
10. The cooling system according to claim 1, Its features are, The thermally conductive medium has an electrical conductivity of less than 10 -8 S / m.
11. The cooling system according to claim 1, Its features are, The busbar is a cell connector or a module connector for the battery.
12. The cooling system according to claim 4, Its features are, The heat-conducting medium is sandwiched between the manifold and the heat exchanger.