Fire suppression arrangement

Abstract

To provide a fire suppression arrangement for suppressing a fire in a battery pack.SOLUTION: A fire suppression arrangement 8 comprises a lithium-ion battery pack 7, and a thermal management system 5 comprising a liquid circuit 13 for circulating a liquid to control the temperature of the lithium-ion battery pack 7. The liquid circuit 13 comprises at least one opening 25 which is closed by a sealing member comprising a fusible portion. The fusible portion is configured to melt when exposed to a temperature above a predetermined activation temperature, thereby allowing liquid to be discharged from the liquid circuit 13 through the opening 25 to cool a portion of the lithium-ion battery pack 7 in the event of an abnormal temperature rise near the opening 25.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire suppression apparatus for suppressing a fire in a battery pack, such as a lithium-ion battery pack, comprising a battery pack and a thermal management system including a fluid circuit for circulating a fluid to control the temperature of the battery pack. [Background technology]

[0002] Rechargeable battery packs, such as lithium-ion battery packs, are widely used in electric vehicles to power one or more electric motors. When such battery packs are charged and discharged, heat is generated within the battery cells of the battery pack. To ensure proper battery performance and avoid thermal runaway, battery temperature is typically controlled by a thermal management system that keeps the temperature within the individual battery cells within a specific temperature range. A typical temperature range is 25-35°C, and various coolants and cooling methods are used.

[0003] Although battery packs are provided with such thermal management systems, there is a risk of thermal runaway and fire. To address this, safety measures in the charging system and battery pack may be used. One such measure is an automatic fire suppression system installed near the battery pack.

[0004] However, known systems are considered to be bulky and / or complex. Summary of the Invention

[0005] SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved fire suppression system for suppressing battery pack fires.

[0006] This and other objects which will become apparent from the following summary and description are achieved by a fire suppression system according to the appended claims.

[0007] According to one aspect of the present disclosure, a fire suppression device for suppressing a fire in a battery pack, such as a lithium-ion battery pack, is provided, the device including: a battery pack; and a thermal management system including a liquid circuit for circulating a liquid to control a temperature of the battery pack. The liquid circuit includes at least one opening closed by a sealing member including a fusible portion configured to melt when exposed to a temperature above a predetermined activation temperature, thereby allowing liquid to be discharged from the liquid circuit through the opening to cool the battery pack in the event of an abnormal temperature increase near the opening.

[0008] The thermal management system may include a liquid pump and a heat exchange unit arranged to circulate liquid through the liquid circuit. During normal operation of the battery pack, the liquid circulating through the liquid circuit serves to regulate the temperature so that it remains within a desired range for optimal performance and lifespan of the battery pack. The circulating liquid also serves to reduce uneven temperature distribution throughout the battery pack. Furthermore, during normal operation of the thermal management system, i.e., when cooling or heating the battery pack, an internal overpressure typically exists within the liquid circuit. Under normal conditions, the fusible portion of the sealing member acts as a stopcock that prevents liquid from escaping through the opening in which the fusible portion of the sealing member is located, as long as the temperature within the battery pack is below an activation temperature. When the temperature of the opening reaches the activation temperature, the fusible portion of the sealing member melts, thereby opening the opening. Liquid then escaping through the opening. In this manner, when the fusible portion melts, the opening forms a drain hole through which the liquid of the thermal management system can be escaping, for example, due to internal pressure within the liquid circuit.

[0009] The fire suppression device provides a combined cooling / heating and fire suppression system, thus achieving a very space and cost efficient solution. Furthermore, such a combined solution is easy to install and provides a solution that can be easily retrofitted to vehicles such as electric buses.

[0010] Furthermore, a highly efficient suppression device is provided since the liquid, such as coolant, can be discharged where it is needed most. Furthermore, a very robust system is achieved since a separate detection system is not required.

[0011] According to one embodiment, the sealing member comprises a mist spray nozzle, the fluid passage and / or the discharge opening of which is sealed by the fusible portion, which has the advantage that more efficient fire suppression is achieved.

[0012] According to one embodiment, the liquid circuit includes several openings, each sealed with a sealing member having a fusible portion. This embodiment provides a more efficient device because the openings can be distributed so that an abnormal temperature rise in any of the battery cells of the battery pack can be detected. This allows for very early suppression of a fire in the battery pack. If the temperature at any location near the sealed opening reaches an activation temperature, the fusible portion of the sealing member located at that opening melts and ceases to function as a plug. Liquid can then be discharged through the opening. Since each opening is activated independently when the activation temperature is reached, the number of openings that operate is limited to only those near the fire, thereby maximizing the available discharge pressure in the area of ​​the fire. The number of openings that open depends on the location and size of the fire. Therefore, since each opening opens due to the heat generated by the fire, several openings can open simultaneously or one after another. Preferably, each sealing member includes a mist spray nozzle, preferably a nozzle capable of spraying mist in the form of an atomized liquid.

[0013] According to one embodiment, the openings are distributed along the entire length of the liquid circuit. Preferably, the openings are uniformly distributed along the entire length of the liquid circuit.

[0014] According to one embodiment, the predetermined activation temperature is in the range of 100-160°C, more preferably 120-150°C, and most preferably 130-150°C.

[0015] According to one embodiment, the predetermined activation temperature is 100°C, more preferably 120°C, most preferably 135°C.

[0016] According to one embodiment, the fusible portion comprises bismuth and / or indium.

[0017] According to one embodiment, the fire suppression device further comprises a housing configured to house the battery pack and the liquid circuit.

[0018] According to one embodiment, the liquid circuit forms an integral part of the housing, preferably the liquid circuit forms an integral part of the bottom of the housing.

[0019] According to one embodiment, the housing is formed from aluminum.

[0020] According to one embodiment, the fire suppression device further comprises a pressure vessel fluidly connected to the thermal management system by a valve assembly. Thus, in this embodiment, the pressure vessel is arranged to pressurize the liquid circuit and preferably supply additional liquid, such as water, to the liquid circuit when the fusible portion melts. In this embodiment, the liquid circuit and other parts of the thermal management system are preferably reinforced. Parts of the thermal management system may be configured to withstand pressures of, for example, at least 70 bar, more preferably at least 90 bar, and most preferably at least 100 bar, to allow pressurized liquid from the pressure vessel to be distributed to the opening(s) and / or nozzle(s).

[0021] According to one embodiment, the valve assembly comprises a release valve.

[0022] According to one embodiment, the valve assembly comprises a one-way valve.

[0023] These and other aspects of the invention will become apparent from and be elucidated with reference to the claims and the embodiments described hereinafter.

[0024] The invention will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 illustrates an electric bus equipped with a fire suppression device according to one embodiment of the present disclosure. [Figure 2] 2 illustrates a battery pack and a liquid circuit of the fire suppression device shown in FIG. 1. [Figure 3] 2 illustrates a portion of the liquid circuit of the fire suppression device shown in FIG. 1. [Figure 4A] This is to illustrate the function of the fire suppression device shown in Figure 1. [Figure 4B] This is to illustrate the function of the fire suppression device shown in Figure 1. [Figure 4C] This is to illustrate the function of the fire suppression device shown in Figure 1. [Figure 5] 10 illustrates a fire suppression device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0026] 1 shows an electric bus 1 provided with a battery pack assembly 3 and a thermal management system 5. Each of the battery pack assembly 3 and the thermal management system 5 is mounted on the roof of the electric bus 1.

[0027] The battery pack assembly 3 comprises three identical battery packs in the form of lithium-ion battery packs, of which a first battery pack 7 is visible in Figure 1. Each of the battery packs 7 is connected to an electric motor (not shown) of the electric bus 1. As illustrated in the exploded portion of Figure 1, the first battery pack 7 comprises several battery modules 9, which are located within a first housing 11.

[0028] The thermal management system 5 comprises a first liquid circuit 13 arranged below the first battery pack 7 in the first housing 11, a second liquid circuit (not shown) arranged below the second battery pack located in the second housing 15, and a third liquid circuit (not shown) arranged below the third battery pack located in the third housing 17.

[0029] As shown in FIG. 2, the liquid circuit 13 is a pipe that extends back and forth across the entire housing 11 in a zigzag pattern.

[0030] The thermal management system 5 further comprises a supply pipe system 18, a return pipe system 19, a heat exchange unit 21, and a liquid pump (not shown) arranged to circulate liquid through each of the liquid circuits 13. The thermal management system 5 serves to control the temperature of the battery packs 7 of the battery pack assembly 3. The thermal management system 5 thus forms a liquid cooling / heating system and is configured to maintain each battery pack 7 at a specific temperature range, for example, between 25 and 35°C. A perforated support plate 23 is arranged between the first liquid circuit 13 and the first battery pack 7, which supports the battery modules 9 of the first battery pack 7 and protects the liquid circuit pipes 13 from damage.

[0031] The first liquid circuit 13 includes a number of openings 25 evenly distributed along the entire length of the liquid circuit 13. Each such opening 25 is sealed with a sealing member comprising a fusible portion. The first battery pack 7 and the thermal management system 5 together form a fire suppression device 8 according to one embodiment of the present disclosure.

[0032] Referring now to Figure 2, the first liquid circuit 13 has a liquid inlet 27 to which a supply pipe 29 of the supply pipe system 18 is connected, and a liquid outlet 31 to which a return pipe 33 of the return pipe system 19 is connected.

[0033] Each opening 25 is sealed with a sealing member comprising a fusible portion. In this embodiment, each opening 25 is sealed with a sealing member in the form of a nozzle 35. Thus, a nozzle 35 is arranged at each of the openings 25 of the liquid circuit 13. The nozzle 35 is, for example, screwed into the pipe 13 of the liquid circuit. Thus, in this embodiment, the openings 25 are sealed with a sealing member comprising a nozzle 35. However, it will be understood that the opening(s) 25 may be sealed with another type of sealing member, such as a fusible plug or a fusible composition. The suppression device 8 formed by the first battery pack 7 and the thermal management system 5 is capable of suppressing a fire and / or preventing thermal runaway of the battery pack 7.

[0034] 3, each nozzle 35 has a fluid passageway 37 with a tapered portion 39 as viewed in the flow direction of the nozzle 35, and an outlet opening 41. The tapered portion 39 allows the liquid to be discharged in the form of a mist, for example, in the form of atomized water. The outlet opening 41 of each nozzle is sealed by a fusible portion 43. In this embodiment, the fusible portion 43 is an alloy comprising bismuth and having a melting point of about 140°C. Preferably, the predetermined activation temperature is in the range of 135-145°C.

[0035] The function of the fire suppression device 8 will now be described with reference to Figures 4A to 4C.

[0036] 4A illustrates a state in which the first battery pack 7 operates at a temperature within a desired temperature range. In this case, the temperature of the battery pack 7 is typically in the range of 25 to 35°C. Then, as illustrated by the arrows, liquid circulates through the liquid circuit 13. Thus, the liquid is supplied from the inlet 27 throughout the liquid circuit pipe 13 and moves in a zigzag pattern to the outlet 31 of the liquid circuit 13. Then, heat can be removed from the battery pack 7 through the heat exchange unit of the thermal management system 5.

[0037] 4B illustrates a fire in a battery cell 47 of one of the battery modules 9 of the battery pack 7, as illustrated by the flames. In this case, the fusible portions 43 of the two nozzles 35 experience an abnormal temperature rise.

[0038] When the temperature of the nozzle 35 exceeds a predetermined activation temperature, in this case 140°C, the fusible portion 43 of the nozzle 35 melts, thereby opening the discharge opening 41 of the nozzle 35, as illustrated in FIG. 4C . Then, as illustrated by the arrows in FIG. 4C , liquid from the liquid circuit 13 is discharged from the discharge opening 41 of the nozzle 35 into the space where the battery module 9 is located to cool its battery cells 47. Thus, a fluid path is established from the liquid circuit 13 of the thermal management system 5 to the area where the fire exists due to the heat generated by the fire in the battery cells 47. The liquid is discharged from the nozzle 35 as mist 49 in the form of an atomized liquid, as illustrated in the upper part of FIG. 4C . The mist very efficiently cools the battery cells 47 of the battery module 9 and suppresses the fire.

[0039] A fire suppression device 108 according to a second embodiment will now be described with reference to Figure 5. Many of the features disclosed in the first embodiment are also present in the second embodiment, and like reference numerals identify similar or identical features. Therefore, this specification will focus on the different features of the second embodiment.

[0040] The second embodiment differs from the first embodiment in that the fire suppression device 108 comprises a pressure vessel 51. The pressure vessel 51 is arranged to pressurize the liquid circuit of the fire suppression device 108 in the event of a fire and to supply additional liquid in the form of pressurized liquid to the liquid circuit. For this purpose, the pressure vessel 51 is filled with a liquid, for example water or another fire-extinguishing liquid, and is capable of driving gas up to approximately 100 bar. In this embodiment, parts of the thermal management system 5, for example the pipes of the supply pipe system, the liquid circuit, and the return pipe system, are reinforced so that they can withstand a pressure of at least 100 bar.

[0041] As illustrated schematically in FIG. 5 , the pressure vessel 51 is provided with a release valve 55 and is connected to the liquid circuit by a pipe connection assembly 53. The release valve 55 may be configured to open in response to a pressure drop in the liquid circuit of the fire suppression device 108 and / or by a separate sensing system. The pressure vessel 51 is thus arranged to distribute pressurized liquid from the pressure vessel 51 to one or more openings and / or nozzles in the liquid circuit of the thermal management system 5 in the event of a fire in the battery pack 7. Thus, in this embodiment, the pressure vessel provided with the release valve is connected to the liquid circuit via a pipe connection. However, it will be understood that the pressure vessel may also be directly connected to the liquid circuit by a valve assembly, such as a release valve or a one-way valve.

[0042] It will be appreciated that many variations of the above-described embodiments are possible within the scope of the appended claims.

Claims

1. A fire suppression device (8) for suppressing a fire in a battery pack such as a lithium-ion battery pack (7), the fire suppression device (8) comprising: The battery pack (7), a thermal management system (5) comprising a liquid circuit (13) for circulating a liquid to control the temperature of the battery pack (7); Equipped with the liquid circuit (13) comprises at least one opening (25) closed by a sealing member (35) comprising a fusible portion (43); The fusible portion (43) is configured to melt when exposed to a temperature above a predetermined activation temperature, thereby allowing liquid to be discharged from the liquid circuit (13) through the opening (25) to cool a portion of the battery pack (7) in the event of an abnormal temperature rise near the opening (25). A fire suppression device (8).

2. 2. The fire suppression device (8) of claim 1, wherein the sealing member comprises a mist spray nozzle (35), the fluid passageway (37, 39, 41) of the mist spray nozzle being sealed by the fusible portion (43).

3. 3. A fire suppression device (8) according to claim 1 or 2, wherein the liquid circuit (13) comprises several openings (25), each of the openings being sealed with a sealing member (35) comprising a fusible portion (43).

4. 4. The fire suppression device (8) of claim 3, wherein each of the sealing members comprises a mist spray nozzle.

5. A fire suppression device (8) according to any one of claims 1 to 4, wherein the predetermined activation temperature is 100°C, more preferably 120°C, most preferably 135°C.

6. A fire suppression device (8) according to any one of claims 1 to 5, wherein the fusible portion comprises bismuth and / or indium.

7. The fire suppression device (8) of any one of claims 1 to 6, further comprising a housing (11) configured to house the battery pack (7) and the liquid circuit (13).

8. 8. The fire suppression device (8) of claim 7, wherein the liquid circuit forms an integral part of the housing (11).

9. The fire suppression system (108) of any one of claims 1 to 8, further comprising a pressure vessel (51) fluidly connected to the thermal management system by a valve assembly (55).

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