Fire suppression device

Abstract

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

Description

Technical Field

[0001] The present invention relates to a fire suppression device for suppressing fire in a battery pack, such as a lithium-ion battery pack. The device comprises a battery pack and a thermal management system comprising a fluid circuit for circulating a fluid 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 power one or more electric motors. As 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, the battery temperature is typically controlled by a thermal management system that maintains the temperature in the individual battery cells within a specific temperature range. The typical temperature range is 25°C to 35°C, using a variety of different coolants and cooling methods.

[0003] Even though the battery pack is equipped with such a thermal management system, there is still a risk of thermal runaway and fire. To address this issue, safety measures can be used in the charging system and the battery pack. One such measure is to install an automatic fire suppression system near the battery pack.

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

[0005] It is an object of the present invention to provide an improved fire suppression device for suppressing a fire in a battery pack.

[0006] This and other objects which will 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, there is provided a fire suppression device for suppressing fire in a battery pack such as a lithium-ion battery pack, the device comprising a battery pack and a thermal management system, the thermal management system comprising a liquid circuit for circulating a liquid to control the temperature of the battery pack. The liquid circuit comprises at least one opening, the opening being closed by a sealing member comprising a fusible portion, wherein 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 through the opening to cool the battery pack when an abnormal temperature increase occurs near the opening.

[0008] The thermal management system may include a liquid pump arranged to circulate the liquid through the liquid circuit and the heat exchange unit. During normal operation of the battery pack, the liquid circulating in the liquid circuit is used to regulate the temperature to keep the temperature within the desired range to achieve optimal performance and life of the battery pack. Moreover, the circulating liquid is also used to reduce the uneven distribution of temperature throughout the battery pack. In addition, during normal operation of the thermal management system, that is, when cooling or heating the battery pack, there is usually an internal overpressure in the liquid circuit. During normal conditions, the fusible portion of the sealing member acts as a closing plug, which prevents the liquid from being discharged from the opening in which the closing plug is arranged as long as the temperature in the battery pack is below the activation temperature. If the temperature at the opening reaches the activation temperature, the fusible portion of the sealing member melts, which opens the opening. Then, the liquid is discharged through the opening. When the fusible portion melts, the opening thus forms a discharge hole, through which the liquid of the thermal management system is discharged, for example, by the internal pressure in the liquid circuit.

[0009] The fire suppression device provides a combined cooling / heating and fire suppression system. Thus a very space-saving and cost-saving solution can be achieved. Furthermore, such a combined solution also provides a solution that is easy to install and can be retrofitted in vehicles such as electric buses in an easy way.

[0010] Furthermore, a very effective suppression device is provided, since the liquid, such as coolant, can be drained where it is most needed. Furthermore, a very robust system is achieved, since no separate detection system is required.

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

[0012] According to one embodiment, the liquid circuit includes a plurality of openings, each of which is sealed by a sealing member including a fusible portion. Since the openings can be distributed so that an abnormal temperature rise in any battery cell of the battery pack is detected, this embodiment provides a more effective arrangement. Therefore, a fire in the battery pack can be suppressed at a very early stage. If the temperature at any position near the sealed opening reaches the activation temperature, the fusible portion of the sealing member arranged in the opening melts and stops acting as a plug. Then, the liquid is allowed to discharge through the opening. Since each opening is activated independently when the activation temperature is reached, the number of openings that work is limited to those near the fire, which maximizes the discharge pressure available in the fire source area. The number of openings to be opened depends on the location and size of the fire. Therefore, since each opening is opened due to the heat generated by the fire, multiple openings can be opened simultaneously or one by one. Preferably, each of the sealing components includes a spray nozzle, and preferably a nozzle that can spray a spray 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 evenly distributed along the entire length of the liquid circuit.

[0014] According to one embodiment, the predetermined activation temperature is in the range of 100°C to 160°C, more preferably in the range of 120°C to 150°C and most preferably in the range of 130°C 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 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 of aluminum. According to one embodiment, the fire suppression device further comprises a pressure vessel, which is fluidly connected to the thermal management system via a valve assembly. In this embodiment, the pressure vessel is therefore arranged to pressurize the liquid circuit and, preferably, to provide additional liquid such as water to the liquid circuit after the fusible part has melted. In this embodiment, the liquid circuit and other components of the thermal management system are preferably reinforced. The components of the thermal management system can, for example, be configured to withstand a pressure of at least 70 bar, more preferably at least 90 bar and most preferably at least 100 bar, so as to be able to distribute the pressurized liquid from the pressure vessel to the (multiple) openings and / or (multiple) nozzles.

[0020] According to one embodiment, the valve assembly comprises a release valve.

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

[0022] These and other aspects of the invention will be apparent from and elucidated with reference to the claims and examples described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0024] Figure 1 An electric bus equipped with a fire suppression device according to an embodiment of the present disclosure is shown.

[0025] Figure 2 Shown Figure 1 Battery and fire suppression device fluid circuit shown.

[0026] Figure 3 Shown Figure 1 A portion of the liquid circuit of a fire suppression device is shown.

[0027] Figures 4A to 4C For display Figure 1 Function of the fire suppression device shown.

[0028] Figure 5 A fire suppression device according to a second embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0029] Figure 1 An electric bus 1 is shown which is equipped with a battery pack assembly 3 and a thermal management system 5. The battery pack assembly 3 and the thermal management system 5 are each mounted on the roof of the electric bus 1.

[0030] The battery pack assembly 3 comprises three identical battery packs in the form of lithium-ion battery packs, Figure 1One of the first battery packs 7 can be seen in FIG. Each battery pack 7 is connected to a motor (not shown) of the electric bus 1. Figure 1 As shown in the exploded part of FIG. 1 , the first battery pack 7 includes a plurality of battery modules 9 , which are located in a first housing 11 .

[0031] The thermal management system 5 includes a first liquid circuit 13, a second liquid circuit (not shown), and a third liquid circuit (not shown). The first liquid circuit is arranged below the first battery group 7 in the first shell 11, the second liquid circuit is arranged below the second battery group in the second shell 15, and the third liquid circuit is arranged below the third battery group in the third shell 17.

[0032] The liquid circuit 13 is a pipe extending back and forth through the housing 11 in a zigzag manner. Figure 2 As displayed.

[0033] The thermal management system 5 further comprises a feed piping system 18, a return piping system 19, a heat exchange unit 21 and a liquid pump (not shown) arranged to circulate liquid throughout each liquid loop 13. The thermal management system 5 is used to control the temperature of the battery packs 7 of the battery pack assembly 3. The thermal management system 5 forming a liquid cooling / heating system is therefore configured to maintain the temperature of each battery pack 7 within a specific temperature range, for example 25° C. to 35° C. A perforated support plate 23 is arranged between the first liquid loop 13 and the first battery pack 7, which supports the battery modules 9 of the first battery pack 7 and protects the liquid loop piping 13 from damage.

[0034] The first liquid circuit 13 includes a plurality of openings 25 evenly distributed along the entire length of the liquid circuit 13. Each such opening 25 is sealed by a sealing member including a fusible portion. According to an embodiment of the present disclosure, the first battery pack 7 and the thermal management system 5 together form a fire suppression device 8.

[0035] Reference now Figure 2 The first liquid circuit 13 has a liquid inlet 27 to which a feed pipe 29 of the feed pipe system 18 is connected, and a liquid outlet 31 to which a return pipe 33 of the return pipe system 19 is connected.

[0036] Each opening 25 is sealed by a sealing member including a fusible portion. In this embodiment, each opening 25 is sealed by a sealing member in the form of a nozzle 35. Therefore, a nozzle 35 is arranged in each opening 25 of the liquid circuit 13. The nozzle 35 is, for example, screwed into the liquid circuit pipe 13. In this embodiment, these openings 25 are therefore sealed by a sealing member including a nozzle 35. However, it should be understood that (multiple) openings 25 can be sealed by 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 in the battery pack 7 and / or preventing thermal runaway therein.

[0037] Reference now Figure 3 , each nozzle 35 has a fluid channel 37 with a tapered portion 39 (viewed from the fluid direction of the nozzle 35) and a discharge opening 41. The tapered portion 39 enables the liquid to be discharged in the form of a spray, 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 containing bismuth and having a melting point of about 140°C. Preferably, the predetermined activation temperature is in the range of 135°C to 145°C.

[0038] The following will refer to Figures 4A to 4C The function of the fire suppression device 8 will be described.

[0039] Figure 4A The state in which the first battery pack 7 operates at a temperature within the desired temperature range is shown. Typically, the temperature in the battery pack 7 is then in the range of 25° C. to 35° C. Then, the liquid circulates in the liquid circuit 13, as shown by the arrows. The liquid is thus fed from the inlet 27 and passes through the liquid circuit pipe 13, and proceeds in a zigzag manner to the outlet 31 of the liquid circuit 13. Then, heat can be removed from the battery pack 7 by the heat exchange unit of the thermal management system 5.

[0040] Figure 4B There is shown a fire exhibited by flames in a battery cell 47 of one of the battery modules 9 of the battery pack 7. Then, the fusible portions 43 of the two nozzles 35 are subjected to an abnormal temperature rise.

[0041] When the temperature at the nozzle 35 exceeds a predetermined activation temperature (140° C. in this case), the fusible portion 43 in the nozzle 35 melts, such as Figure 4CAs shown, this opens the discharge opening 41 of the nozzle 35. Then, as shown by the arrow in FIG. 4c, the liquid from the liquid circuit 13 is discharged through the discharge opening 41 of the nozzle 35 to the space where the battery module 9 is located to cool its battery cells 47. Due to the heat generated by the fire in the battery cells 47, a fluid passage is established from the liquid circuit 13 of the thermal management system 5 to the fire area. The liquid is discharged through the nozzle 35 as a spray 49 in the form of atomized liquid, as shown in FIG. Figure 4C The spray cools the battery cells 47 of the battery module 9 in a very effective manner, which suppresses the fire.

[0042] The following will refer to Figure 5 The fire suppression device 108 according to the second embodiment will be described. Many of the features disclosed in the first embodiment also exist in the second embodiment, and the second embodiment uses similar reference numerals to indicate similar or identical features. Having mentioned this, the description will focus on explaining the different features of the second embodiment.

[0043] 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 and to provide additional liquid in the form of pressurized liquid to the liquid circuit in the event of a fire. To this end, the pressure vessel 51 may be filled with a liquid, such as water or other fire extinguishing liquid, and a driving gas of up to about 100 bar. In this embodiment, components of the thermal management system 5, such as the pipes of the feed pipe system, the liquid circuit and the return pipe system, are reinforced to withstand a pressure of at least 100 bar.

[0044] The pressure vessel 51 is equipped with a release valve 55 and connected to a liquid circuit via a pipe connection assembly 53, such as Figure 5 Schematically illustrated. 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 an independent 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 of the liquid circuit of the thermal management system 5 in the event of a fire in the battery pack 7. In this embodiment, the pressure vessel equipped with the release valve is thus connected to the liquid circuit via a pipe connection. However, it should be understood that the pressure vessel may be directly connected to the liquid circuit via a valve assembly, for example via a release valve or a non-return valve.

[0045] It will be appreciated that many variations of the embodiments described above are possible within the scope of the appended claims.

Claims

1. A fire suppression device (8) for suppressing a fire in a battery pack (7), the device (8) comprising the battery pack (7), and a thermal management system (5) comprising a liquid circuit (13) for circulating a liquid to control the temperature of the battery pack (7), It is characterized in that a perforated support plate (23) arranged between the liquid circuit (13) and the battery pack (7), wherein at least one sealing member (35) including a fusible portion (43) is arranged on the perforated support plate by being inserted into at least one hole of the perforated support plate, The liquid circuit (13) has a tube wall comprising at least one opening (25) corresponding to at least one hole of the perforated support plate (23), the opening being closed by a sealing member (35) comprising a fusible portion (43) by inserting the sealing member (35) into the opening via the hole, wherein 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) when an abnormal temperature increase occurs near the opening (25).

2. The fire suppression device according to claim 1, wherein: The sealing member includes a spray nozzle whose fluid passage is sealed by the fusible portion (43).

3. A fire suppression device (8) according to any one of the preceding claims, wherein: The liquid circuit (13) comprises a plurality of openings (25), each of which is sealed by a sealing member (35) comprising a fusible portion (43).

4. The fire suppression device according to claim 3, wherein: Each of the sealing members includes a spray nozzle.

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

6. The fire suppression device (8) according to claim 1 or 2, wherein: The fusible portion includes bismuth and / or indium.

7. The fire suppression device according to claim 1 or 2, wherein: The fire suppression device further comprises a housing (11) configured to accommodate the battery pack (7) and the liquid circuit (13).

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

9. The fire suppression device according to claim 1 or 2, wherein: The fire suppression device further comprises a pressure vessel (51) which is fluidly connected to the thermal management system via a valve assembly (55).

10. The fire suppression device according to claim 1, wherein: The battery pack is a lithium-ion battery pack.

11. The fire suppression device (8) according to claim 1 or 2, wherein: The predetermined activation temperature is 120°C.

12. The fire suppression device (8) according to claim 1 or 2, wherein: The predetermined activation temperature is 135°C.

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