Extinguishing system and an electric vehicle incorporating this system and method for distributing a fluid in a battery arrangement

Abstract

In various embodiments, a fire suppression system for distributing a fluid in a battery assembly (8) of an electric vehicle (F) is described, comprising: a fluid distribution system (2) arranged outside the battery assembly (8) in the vehicle body; at least one first access port (5) arranged between the fluid distribution system (2) and the battery assembly (8) of the electric vehicle (F); and at least one outlet (7) arranged on the battery assembly (8) and configured to discharge the fluid introduced into the battery assembly (8). Furthermore, an electric vehicle equipped with such a fire suppression system and a method for distributing a fluid in a battery assembly (8) of an electric vehicle (F) in the event of a fire are described.

Description

[0001] The present invention relates to an extinguishing system and a method for distributing a fluid in a battery assembly of an electric vehicle, and to an electric vehicle having the same. Furthermore, an electric vehicle having the extinguishing system is provided.

[0002] A clear global trend toward electric passenger transport is evident. While 5% of vehicles sold were electric in 2020, this share rose to 9% in 2021 and already reached 14% in 2022. This trend is equally evident in all major markets, with the Chinese market accounting for the largest share of this development so far.

[0003] In partially and fully electric vehicles, which currently include vehicles in the mHEV (mild hybrid electric vehicle), sHEV (series hybrid electric vehicle), PHEV (plug-in hybrid electric vehicle), E-REV (extended range electric vehicle) and BEV (battery electric vehicle) classes, a rechargeable battery is used to store electrical energy. The term electric vehicle is used below, but this is intended to refer to any of the aforementioned classes. The batteries used in electric vehicles usually consist of a combination of several high-energy individual rechargeable battery cells. These battery cells can be designed as cylindrical cells, flat pouch cells or prismatic cells. In battery-electric vehicles in particular, the battery is usually positioned as low as possible in order to achieve a low center of gravity for the overall vehicle despite its high weight.The battery is usually positioned in the vehicle floor between the axles.

[0004] While at the beginning of electric vehicle development, the battery was not designed as a load-bearing, structural component, the transition is now taking place to structural battery modules, which are designed to support the body's load. Accordingly, the battery enclosure is designed as a structural, significantly more stable component.

[0005] Due to the cell chemistry used, combined with relatively high energy capacities in the range of 100 kWh, these vehicles are difficult to extinguish in the event of a fire and pose significant challenges for fire departments around the world. While the frequency of fires in electric vehicles is not significantly different from those in vehicles with combustion engines, the danger potential in the event of a fire is significantly higher.

[0006] The process of a battery cell fire, known as "thermal runaway," can be considered a worst-case scenario and is very difficult to extinguish, especially if the fire spreads from the affected battery cell to neighboring battery cells. When a battery cell catches fire, the chemically stored energy is released through an exothermic chemical reaction. The increase in both the energy density of the cells and the capacity of the entire battery or the associated battery modules leads to more powerful chemical reactions. While the energy density of lithium-ion batteries was around 0.9 kW / l in 2010, modern lithium-ion batteries can now achieve nine times higher energy densities, in the range of 4.5 kW / l and more. The higher power levels lead to a very large release of energy in the event of a thermal runaway.Even after the extinguishing process has been completed, the defective battery must be monitored for a long period of time, as it may reignite.

[0007] Thermal failure of batteries can be triggered by several mechanisms. Regardless of the cause, a thermal runway occurs when the oxide decomposes, releasing oxygen, which reacts chemically with cell components. This process leads to a self-reinforcing, unstoppable, exothermic reaction that can result in the complete thermal destruction of the battery. This generally applies to all known cathode materials. The cathode materials differ in the onset temperature at which the thermal reaction begins and the energy released.

[0008] While vehicles with conventional combustion engines can be effectively extinguished with water, CO2, or firefighting foam in the event of a fire, the options for battery-equipped vehicles are limited due to the chemical reactions involved. Since the fire cannot be reliably extinguished by spraying with water, deoxygenating with CO2, or by fire blankets, these methods are only partially effective.

[0009] Since small amounts of water can actually worsen the progression of a fire, fire departments have resorted to submerging burning vehicles in fire extinguishing containers for several hours, if possible. This allows the resulting temperatures to be controlled and re-ignition to be prevented. However, these water containers must first be transported to the scene of the fire and filled, and are not available at every fire station. In addition, the fire extinguishing containers are tied to the scene for at least 24 hours while the vehicle being extinguished is submerged.

[0010] In response to these complex requirements and in the absence of better alternatives, fire departments have resorted to cooling vehicle batteries with water as best as possible. To do this, burning vehicles without access to a water container are temporarily jacked up and the underbody is sprayed with water. This method is ineffective and results in high water consumption. Since the extinguishing water can only cool the battery externally, the cooling effect on the battery cells is minimal. Thermal runaway of the battery cannot be reliably prevented.

[0011] In tests on batteries in a thermal runway condition, the Swedish Civil Contingencies Agency was able to show that directly injecting water into a battery is a more effective extinguishing method that can also prevent reignition. For the test, various tools were tested to penetrate the battery enclosure. During the tests, a high-pressure lance was used to shoot through the vehicle floor. This made it possible to reach the interior of the battery and thus the continuous battery cells with extinguishing water. However, this requires the person carrying out this process to remain in the immediate vicinity of the burning vehicle for an extended period of time. Furthermore, the reliability of this method is questionable because, depending on the vehicle and the penetration point, an undefined number of layers of various materials have to be penetrated.Reliable fire fighting with extinguishing water across all vehicle models cannot be guaranteed using this method.

[0012] A major problem with extinguishing batteries in electric vehicles is their central installation within the vehicle. This prevents the extinguishing agent from reaching the burning components. When water is used as the extinguishing agent, the installation and enclosure of the battery or battery modules prevent the extinguishing water from effectively cooling the reacting battery cells. Consequently, the only extinguishing solutions left are submerging the entire vehicle in a water container or the ineffective spraying of the underbody.

[0013] From document DE 102020131108 A1, a battery for a motor vehicle is known, which has a flooding device with at least one supply connection for flooding the battery. The battery is designed to introduce a cooling medium supplied to the at least one supply connection into the battery housing. The flooding device has a housing structure that encloses the battery, leaving a flow-through space surrounding the battery housing on all sides. The flooding device is designed to supply a cooling medium supplied to the at least one supply connection to the space.

[0014] Against this background, the object of the present invention can be seen in providing a possibility with which a vehicle, in particular its battery, can be extinguished effectively and reliably in the event of a fire.

[0015] This object is achieved by means of the subject matter of the independent patent claims. Further preferred embodiments can be found in the dependent patent claims.

[0016] The present invention is based on the basic idea of ​​directing water, for example, as a cooling or extinguishing fluid, directly to the location of the fire in order to effectively cool the battery cells and thus extinguish the fire. Water not only acts as an inert medium to extinguish a fire, but also as a coolant to cool the cells below the critical onset temperature.

[0017] The invention is characterized by a systematic approach to connecting the vehicle's bodyshell structure to the battery through a channel system, enabling complete circulation of an extinguishing fluid within the battery and its drainage in the event of a fire. The extinguishing process can be initiated by injecting water, for example, into the vehicle body using an extinguishing lance. This enables a quick and efficient way to cool the battery cells with water.

[0018] According to the invention, various embodiments provide an extinguishing system for distributing a fluid in a battery assembly of an electric vehicle. The fluid can be a gas or a liquid that can be used to cool and / or extinguish a battery fire. The battery assembly can have a housing in which battery modules containing battery cells are arranged. Alternatively, the battery modules can be provided without a central battery housing. The battery assembly can, in particular, be an HV battery of an electric vehicle.

[0019] The extinguishing system according to the invention has a fluid distribution system arranged outside the battery arrangement in the vehicle body. The fluid distribution system can, in particular, be a piping system designed to introduce and distribute the fluid. For this purpose, at least one first access port is provided, which is arranged between the fluid distribution system and the battery arrangement of the electric vehicle. The fluid flowing through the fluid distribution system is introduced into the battery arrangement through the at least one first access port, and the battery arrangement is filled with the fluid. Depending on the embodiment of the battery arrangement, the fluid can be introduced into a housing enclosing the battery modules or into the battery module housings.

[0020] Additionally, at least one outlet is provided, which is arranged on the battery assembly and serves to drain / remove the fluid introduced into the battery assembly. When the outlet is released (open), a fluid flow can be established through the battery assembly.

[0021] According to further embodiments of the extinguishing system, at least part of the fluid distribution system can be integrated into the chassis of the electric vehicle, in the case of vehicles with a self-supporting body, into the floor pan. The chassis represents a stable, load-bearing part of the vehicle and stabilizes it against external forces. Integrating the fluid distribution system into the chassis can increase the likelihood that it will remain intact even in the event of an accident and can be used for an extinguishing operation.

[0022] According to further embodiments of the extinguishing system, at least part of the fluid distribution system can run in at least one of the sills of the electric vehicle. Access to the body's fluid distribution system can be possible via the entire vehicle sill, in which case—unless a separate access is used—the body material must be penetrated, for example, with an extinguishing lance. Existing cavities in at least one of the two sills can preferably be connected to one another by openings, creating well-protected flow paths for the fluid that do not require additional installation space.

[0023] According to further embodiments of the extinguishing system, the at least one first access port can be closed with a closure element configured to release the at least one first access port in a pressure-dependent manner. The closure element can be a rupture disc or a valve that ruptures or opens at a predetermined pressure of the introduced fluid, thus releasing the at least one first access port.

[0024] According to further embodiments of the extinguishing system, the at least one outlet can be closed with a closure element configured to release the at least one outlet depending on pressure. The closure element of the outlet can generally be designed in the same way as the closure element of the at least one access port. The predetermined pressure at which the outlet closure element is released or opens can be higher than the predetermined pressure at which the access port closure element opens. Thus, the pressure at which the fluid is introduced into the fluid distribution system can be used to control whether the battery arrangement should merely be filled with the fluid or whether a flow of the fluid should be established through the battery arrangement.

[0025] According to further embodiments of the extinguishing system, it can further comprise at least one second access port, which is arranged on the vehicle body and fluidly coupled to the fluid distribution system. The at least one second access port can be arranged, for example, in the area of ​​the sill. For safety reasons, second access ports can be mounted anywhere on the vehicle body and fluidly coupled to the fluid distribution system by means of lines, which are preferably arranged in load-bearing parts of the body. This practically guarantees that, in the event of an accident in which the vehicle has rolled over or collided sideways with another vehicle, a second access port is always accessible, regardless of the vehicle's position.

[0026] According to further embodiments of the extinguishing system, the battery assembly can comprise a number of battery modules, each of which has an array of battery cells. Each of the battery modules is designed such that a fluid introduced into the battery assembly by the fluid distribution system can come into contact with the battery cells. For this purpose, at least one fluid inlet and at least one fluid outlet can be provided on each of the battery modules.

[0027] According to further embodiments of the extinguishing system, the battery assembly can have at least one hollow chamber, which is fluidly connected to the fluid distribution system via the first access port and surrounds battery modules and / or battery cells of the battery assembly. The extinguishing fluid can be distributed around the battery modules via the at least one hollow chamber surrounding the battery assembly. The hollow chamber can, in particular, correspond to the battery housing in which the battery modules are arranged.

[0028] According to the invention, an electric vehicle is further provided which has an extinguishing system according to one of the embodiments described above.

[0029] According to the invention, a method for distributing a fluid in a battery assembly of an electric vehicle in the event of a fire is further provided, wherein the method comprises introducing a fluid into a fluid distribution system arranged in the vehicle body in order to flow the fluid through the battery assembly. Here, at least one first access port is arranged between the fluid distribution system and the battery assembly of the electric vehicle, and furthermore, at least one outlet is arranged on the battery assembly, which is configured to drain the fluid introduced into the battery assembly. The fluid distribution system can in particular be the fluid distribution system according to one of the previously described embodiments.

[0030] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0031] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Fig. 1 shows a typical damage progression in a battery fire. Fig. 2 shows a schematic representation of an extinguishing system according to various embodiments in the inactivated state. Fig. 3 shows a schematic representation of an extinguishing system according to various embodiments in the activated state. Fig. 4 shows a common structure of a lower part of a vehicle body. Fig. 5 shows another embodiment of the extinguishing system in the active state. Fig. 6 shows an electric vehicle with an extinguishing system according to the present invention.

[0032] In Fig. Figure 1 outlines the damage progression of a battery, specifically a battery in an electric vehicle. Thermal failure of batteries can be triggered by several mechanisms. First, in a first phase P1, cell failure is caused by excessive temperature. Depending on the oxide, temperatures as low as 180°C can lead to a thermal runaway event and the triggering of the thermal chain reaction, which corresponds to the second phase P2. Another mechanism is mechanical damage to the insulator. If the insulation, also called the separator, is damaged in a cell in the battery assembly, a brief discharge occurs, which leads to the cell overheating. The energy chemically stored in the cell is suddenly released.This thermal reaction then leads to a chain reaction in a third phase (P3) involving the surrounding cells and, in the worst case, can spread to all battery cells. This process is also known as thermal runaway.

[0033] To counteract thermal runaway, the extinguishing system according to the invention can be used, which is Fig. 2 is shown schematically. It shows a chassis 1 of a vehicle, here an electric vehicle, which has front longitudinal members 3 and rear longitudinal members 4. The extinguishing system is arranged between the longitudinal members 3, 4 and has a fluid distribution system 2, which is arranged outside the battery assembly 8 in the vehicle body. In the exemplary embodiment shown, the fluid distribution system 2 extends within the two side sills S and into the cross members connecting them. In principle, the body of the vehicle, which surrounds the battery assembly 8, is provided for the fluid line.

[0034] The fluid distribution system 2 is fluidically coupled to the battery assembly 8 of the electric vehicle via a plurality of first access ports 5. In Fig. 1, however, the extinguishing system is shown in an inactive state, in which the first access ports 5 are closed with closure elements 51. Furthermore, an outlet 7 is provided, also closed with a corresponding closure element, which is arranged on the battery assembly 8 and is designed to drain the fluid introduced into the battery assembly 8. A second access port 6 is provided for introducing a fluid into the fluid distribution system 2, which is closed with an associated closure element 61. Here, the access port is attached to the side sill S.

[0035] In Fig. 3 is the extinguishing system Fig. 2 is shown in an activated state, in which an extinguishing medium, here water 9, has first been introduced into the fluid distribution system 2 through the second access port 6, and then introduced into the battery arrangement 8 via existing cavities (e.g., in the sills S) and additionally introduced channels / lines. At a defined extinguishing water pressure in the battery 8, the water drains via the outlet 7 to enable effective extinguishing water circulation.

[0036] Fig. Figure 4 shows a typical vehicle body structure in the area of ​​the sill S. Within the sill S, which is part of the chassis, there are cavities H1, H2 separated by partition walls T. The battery assembly 8 is located centrally in the chassis, in which the individual battery modules 10 are arranged in a battery housing 11. The battery housing 11 is mechanically and stably connected to the sills S.

[0037] In Fig. Figure 5 shows an embodiment of the extinguishing system in the inactive state. Here, the partition wall T in the sill was first penetrated to connect the two cavities H1, H2 – these function as lines of the fluid line system 2. Furthermore, a first access port 5 (shown here in the open state) is arranged between the sill S and the battery assembly 8, through which the fluid can flow from the sill S into the interior of the battery assembly 8, so that the battery modules 10 are surrounded by the cooling / extinguishing water 9. The first access port 5 only opens when subjected to a defined extinguishing water pressure.Channels present in the battery arrangement 8, for example in the form of air gaps and / or incorporated channels 9, allow for a controlled introduction of cooling water 9, thereby creating an efficient way to reduce the temperatures of the burning battery cells (not explicitly shown) within the battery modules 10 and extinguish a fire. For this purpose, corresponding ports can be provided in the housings of the battery modules 10, allowing the extinguishing fluid to flow in and out.

[0038] In Fig.6 shows an electric vehicle F with an electric drive train and an extinguishing system according to the present invention integrated therein. In the event of a fire, extinguishing water can be introduced into the battery assembly in a controlled manner via the body shell of the vehicle F via the second access port 6 provided on the sill S. The cooling water then flows, indicated by the arrows, through channels of the fluid distribution system into usually separate areas of the battery assembly 8. The closure elements of the access ports 5, 6 open at a defined extinguishing water pressure, thus allowing access to the normally closed areas within the battery assembly.

[0039] As previously mentioned, the second access port 6 is useful, but optional. Alternatively or additionally, the body material in the area of ​​the sill S can be penetrated, for example, using an extinguishing lance, to provide access to the fluid distribution system at any point on the sill S. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102020131108 A1

[0013]

Claims

[1] Extinguishing system for distributing a fluid in a battery arrangement (8) of an electric vehicle (F), comprising: a fluid distribution system (2) arranged outside the battery arrangement (8) in the vehicle body; at least one first access port (5) arranged between the fluid distribution system (2) and the battery arrangement (8) of the electric vehicle (F); at least one outlet (7) which is arranged on the battery arrangement (8) and is designed to drain the fluid introduced into the battery arrangement (8). [2] Extinguishing system according to claim 1, wherein at least part of the fluid distribution system (2) is integrated into the chassis of the electric vehicle. [3] Extinguishing system according to claim 1 or 2, wherein at least a part of the fluid distribution system (2) runs in at least one of the sills (S) of the electric vehicle (F). [4] Extinguishing system according to one of claims 1 to 3, wherein the at least one first access port (5) is closed with a closure element (51) which is designed to release the first access port (5) in a pressure-dependent manner. [5] Extinguishing system according to one of claims 1 to 4, wherein the at least one outlet (7) is closed with a closure element which is designed to release the outlet (7) in a pressure-dependent manner. [6] Extinguishing system according to one of claims 1 to 5, further comprising: at least one second access port (6) which is arranged on the vehicle body and is fluidly coupled to the fluid distribution system. [7] Extinguishing system according to one of claims 1 to 6, wherein the battery arrangement (8) comprises a number of battery modules (10), each of which comprises an arrangement of battery cells, wherein each of the battery modules (10) is designed such that a fluid flowing into the battery arrangement (8) through the fluid distribution system (2) can come into contact with the battery cells. [8] Extinguishing system according to one of claims 1 to 7, wherein the battery arrangement (8) has at least one hollow chamber which is fluidly connected to the fluid distribution system (2) via the first access port (5) and surrounds battery modules (10) and / or battery cells of the battery arrangement (8). [9] Electric vehicle (F) comprising an extinguishing system according to one of the preceding claims. [10] Method for distributing a fluid in a battery arrangement (8) of an electric vehicle (F) in the event of a fire, comprising: Introducing a fluid into a fluid distribution system (2) which is arranged in the vehicle body outside the battery arrangement (8) in order to flow through the battery arrangement (8) with the fluid; wherein at least one first access port (5) is arranged between the fluid distribution system (2) and the battery arrangement (8) of the electric vehicle (F) and furthermore, at least one outlet (7) is arranged on the battery arrangement (8), which is designed to drain the fluid introduced into the battery arrangement (8).

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