Fire suppression device

Abstract

The present invention relates to a fire suppression device (8) for suppressing a fire in a battery pack, such as a lithium-ion battery pack (7), comprising the battery pack (7) and a thermal management system (5) including a liquid circuit (13) for circulating liquid to control the temperature of the battery pack (7). The liquid circuit (13) includes at least one opening (25) closed by a sealing member (35) including a fusible portion (43) 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 increase near the opening (25).

Description

Technical Field

[0001] The present invention relates to a fire suppression device for suppressing a fire in a battery pack such as a lithium-ion battery pack. The device includes a battery pack and a thermal management system including a liquid circuit for circulating a liquid to control the temperature of the battery pack.

Background Art

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

[0003] Although such a thermal management system is provided for the battery pack, there is a risk of thermal runaway and fire. To address this, safety measures in the charging system and the battery pack can 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] An object of the present invention is to provide an improvement in a fire suppression device for suppressing a fire in a battery pack.

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

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

[0008] The thermal management system may comprise a liquid pump and a heat exchange unit, arranged to circulate liquid through a liquid circuit. During normal operation of the battery pack, the liquid circulating in the liquid circuit regulates the temperature to remain within a desired range for optimal performance and lifespan of the battery pack. The circulating liquid also reduces the 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, internal overpressure is usually present in the liquid circuit. Under normal conditions, the fusible portion of the sealing member acts as a stopper, preventing liquid from being discharged from the opening where the fusible portion of the sealing member is located, as long as the temperature inside the battery pack is below the 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 is then discharged from the opening. In this way, when the fusible portion melts, the opening forms a drain hole through which the liquid from the thermal management system is discharged, for example, by the internal pressure in the liquid circuit.

[0009] The fire suppression device provides a system that combines cooling / heating with fire suppression. Therefore, it can achieve a highly space- and cost-effective solution. Furthermore, such a combined solution is easy to install and can be easily retrofitted to vehicles such as electric buses.

[0010] Furthermore, since liquids such as coolants can be discharged where they are most needed, a highly efficient suppression device is provided. In addition, a very robust system is achieved because a separate detection system is not required.

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

[0012] According to one embodiment, the liquid circuit has 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. Thus, a battery pack fire can be suppressed very early. When the temperature at any location near a sealed opening reaches the activation temperature, the fusible portion of the sealing member placed in that opening melts and ceases to function as a stopper. The liquid can then be discharged from the opening. Since each opening is activated independently when it reaches the activation temperature, the number of operating openings is limited to those near the fire, thereby maximizing the available discharge pressure in the area of ​​the fire source. The number of openings depends on the location and size of the fire. Therefore, since each opening opens due to the heat generated by the fire, several openings may open simultaneously or successively. Preferably, each of the sealing members is equipped with a mist spraying nozzle, preferably a nozzle capable of spraying a mist in the form of a liquid atomizer.

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

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

[0015] According to one embodiment, the predetermined activation temperature is 100°C, more preferably 120°C, and 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 accommodate 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. Multiple 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, so that pressurized liquid from the pressure vessel can be distributed to openings (one or more) and / or nozzles (one or more).

[0021] According to one embodiment, the valve assembly comprises a discharge 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 the claims and the embodiments described below, and will be elucidated by reference thereto.

[0024] Next, the present invention will be described in more detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] An electric bus provided with a fire suppression device according to an embodiment of the present disclosure is shown. [Figure 2] The battery pack and the liquid circuit of the fire suppression device shown in FIG. 1 are illustrated. [Figure 3] A part of the liquid circuit of the fire suppression device shown in FIG. 1 is illustrated. [Figure 4A] It is for illustrating the function of the fire suppression device shown in FIG. 1. [Figure 4B] It is for illustrating the function of the fire suppression device shown in FIG. 1. [Figure 4C] It is for illustrating the function of the fire suppression device shown in FIG. 1. [Figure 5] A fire suppression device according to a second embodiment of the present disclosure is illustrated.

Modes for Carrying Out the Invention

[0026] FIG. 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 includes three identical battery packs in the form of lithium-ion battery packs, and the first battery pack 7 thereof is visible in FIG. 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 part of FIG. 1, the first battery pack 7 includes several battery modules 9, and the battery modules 9 are located within the first housing 11.

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

[0029] The liquid circuit 13 is a pipe that extends in a zigzag pattern across the entire housing 11, as illustrated in Figure 2.

[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 controls the temperature of the battery packs 7 of the battery pack assembly 3. Thus, the thermal management system 5, which forms a liquid cooling / heating system, is configured to maintain each battery pack 7 at a specific temperature range, for example, 25-35°C. Between the first liquid circuit 13 and the first battery pack 7, a perforated support plate 23 is positioned to support the battery module 9 of the first battery pack 7 and protect the liquid circuit pipes 13 from damage.

[0031] The first liquid circuit 13 includes several openings 25 uniformly distributed along the entire length of the liquid circuit 13. Each such opening 25 is sealed with a sealing member having 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] Next, referring to Figure 2, the first liquid circuit 13 has a liquid inlet 27 to which the supply pipe 29 of the supply pipe system 18 is connected, and a liquid outlet 31 to which the return pipe 33 of the return pipe system 19 is connected.

[0033] Each opening 25 is sealed with a sealing member having 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 placed in each of the openings 25 of the liquid circuit 13. The nozzle 35 is screwed into, for example, 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 is 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 fire and / or preventing thermal runaway of the battery pack 7.

[0034] Referring next to Figure 3, each nozzle 35 has a fluid passage 37 having a tapered portion 39 when viewed from the fluid direction of the nozzle 35, and a discharge 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 discharge 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 to 145°C.

[0035] Referring to Figures 4A to 4C, the function of the fire suppression device 8 is described below.

[0036] Figure 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, the liquid circulates within 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. Heat can then be removed from the battery pack 7 via the heat exchange unit of the thermal management system 5.

[0037] Figure 4B illustrates a fire in a battery cell 47 of one of the battery modules 9 of the battery pack 7, illustrated by 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, as illustrated in Figure 4C, and this opens the discharge opening 41 of the nozzle 35. Then, as illustrated by the arrows in Figure 4C, the 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, cooling its battery cells 47. Thus, a fluid passage from the liquid circuit 13 of the thermal management system 5 to the area where the fire is present is established due to the heat generated by the fire in the battery cells 47. The liquid is discharged from the nozzle 35 as a mist 49 in the form of a fine liquid atom, as illustrated in the upper part of Figure 4C. The mist cools the battery cells 47 of the battery module 9 very efficiently and suppresses the fire.

[0039] The fire suppression device 108 according to the 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 similar reference numerals identify the same 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 includes a pressure vessel 51. The pressure vessel 51 is arranged to pressurize the liquid circuit of the fire suppression device 108 and supply additional liquid to the liquid circuit in the form of pressurized liquid in the event of a fire. For this purpose, the pressure vessel 51 is filled with liquid, such as water or other fire extinguishing fluid, and can drive the gas up to about 100 bar. In this embodiment, the pipes of several parts of the thermal management system 5, such as the supply pipe system, the liquid circuit, and the return pipe system, are reinforced to withstand pressures of at least 100 bar.

[0041] As schematically illustrated in Figure 5, the pressure vessel 51 is provided with a release valve 55, and the pressure vessel 51 is connected to the liquid circuit by a pipe coupling 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. Thus, the pressure vessel 51 is positioned 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 coupling. However, it is understood that the pressure vessel may be directly connected to the liquid circuit by a valve assembly, for example, by a release valve or a one-way valve.

[0042] It will be understood that numerous variations of the above-described embodiments are possible within the scope of the attached claims. The invention described in the original claims of this application is listed below. [1] In a fire suppression device (8) for suppressing fires in battery packs such as lithium-ion battery packs (7), the fire suppression device (8) is: The aforementioned battery pack (7), A thermal management system (5) is provided with a liquid circuit (13) for circulating liquid to control the temperature of the battery pack (7), Equipped with, The liquid circuit (13) has at least one opening (25) that is closed by a sealing member (35) having a fusible portion (43), The fusible portion (43) is configured to melt when exposed to a temperature above a predetermined activation temperature, thereby enabling the 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) characterized by the following: [2] The fire suppression device (8) according to [1], wherein the sealing member comprises a mist spray nozzle (35), and the fluid passages (37, 39, 41) of the mist spray nozzle are sealed by the fusible portion (43). [3] The fire suppression device (8) according to [1] or [2], wherein the liquid circuit (13) comprises several openings (25), each of which openings is sealed by a sealing member (35) having a fusible portion (43). [4] Each of the sealing members is provided with a mist spray nozzle, the fire suppression device (8) according to [3]. [5] The fire suppression device (8) according to any one of [1] to [4], wherein the predetermined activation temperature is 100°C, more preferably 120°C, and most preferably 135°C. [6] The fire suppression device (8) according to any one of [1] to [5], wherein the fusible portion comprises bismuth and / or indium. [7] The fire suppression device (8) according to any one of [1] to [6], further comprising a housing (11) configured to house the battery pack (7) and the liquid circuit (13). [8] The liquid circuit forms an integral part of the housing (11) and is the fire suppression device (8) described in [7]. [9] A fire suppression device (108) according to any one of [1] to [8], further comprising a pressure vessel (51) which is fluidly connected to the thermal management system by a valve assembly (55).

Claims

1. In a fire suppression device (8) for suppressing fire in a battery pack (7), the fire suppression device (8) is: The aforementioned battery pack (7), A thermal management system (5) is provided with a liquid circuit (13) for circulating liquid to control the temperature of the battery pack (7), Equipped with, The liquid circuit (13) is provided with several openings (25), each of which is sealed with a sealing member (35) having a fusible portion (43). The fusible portion (43) is configured to melt when exposed to a temperature exceeding a predetermined activation temperature, thereby enabling the liquid to be discharged from the liquid circuit (13) through the opening (25) to cool a portion of the battery pack (7) when an abnormal temperature rise occurs near the opening (25). Each of the sealing members is equipped with a mist spray nozzle (35), and the fluid passages (37, 39, 41) of the mist spray nozzle are sealed by the fusible portion (43). A fire suppression device (8) characterized by the following.

2. The fire suppression device (8) according to claim 1, wherein the predetermined activation temperature is 100°C.

3. The fire suppression device (8) according to claim 1 or 2, wherein the fusible portion comprises bismuth and / or indium.

4. The fire suppression device (8) according to any one of claims 1 to 3, further comprising a housing (11) configured to house the battery pack (7) and the liquid circuit (13).

5. The fire suppression device (8) according to claim 4, wherein the liquid circuit forms an integral part of the housing (11).

6. A fire suppression device (108) according to any one of claims 1 to 5, further comprising a pressure vessel (51) fluidly connected to the thermal management system by a valve assembly (55).

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