Intermittent spray type fire extinguishing apparatus having pressure relief structure, and method

Abstract

Disclosed in the present invention are an intermittent spray type fire extinguishing apparatus having a pressure relief structure, and a method. The fire extinguishing apparatus comprises a housing and a gas-producing fire extinguishing agent arranged in the housing. A front cover is arranged on the front side of the housing. A plurality of nozzles is formed in the surface of the front cover. The end face of the gas-producing fire extinguishing agent is connected to one end of an activation part. A piston in sliding fit with the housing is arranged inside the housing. The piston is connected to the bottom of the front cover by means of a screw of a ball screw mechanism. The top of the screw is fixedly connected to the center of a rotating cover. A liquid fire extinguishing agent is arranged between the piston and the front cover. Spray holes are formed on the surface of the rotating cover. When the rotating cover rotates, the spray holes and the nozzles periodically overlap and intersect. A pressure relief diaphragm is arranged on the surface of some of the nozzles of the front cover surface. The piston comprises an outer ring piston located outside, and an inner piston located inside. The screw is arranged in the inner piston in a penetrating mode. By means of the present solution, an intermittent spray process can be continuously carried out, and the risk of re-combustion is prevented. In addition, pressure relief is achieved, and the safety of the fire extinguishing apparatus in the fire extinguishing process is ensured.

Description

An intermittent spraying fire extinguishing device and method with a pressure relief structure Technical Field

[0001] The present invention relates to the technical field of new energy battery fire extinguishing, and in particular to an intermittent spraying fire extinguishing device and method with a pressure relief structure. Background Art

[0002] When new energy batteries experience thermal runaway, they often continue to produce flammable gases. Traditional aerosol fire extinguishing devices are difficult to extinguish the flames instantly. Pulse fire extinguishing devices can extinguish the flames instantly but cannot achieve the effect of continuous suppression. When the pulse fire extinguishing device is used in combination with the traditional aerosol fire extinguishing device, the pulse fire extinguishing device can extinguish the flames instantly generated by the battery thermal runaway, and the traditional aerosol fire extinguishing device can suppress the flames to a certain extent after the pulse fire extinguishing device is sprayed. Theoretically, the combination of the two overcomes each other's shortcomings and can extinguish the flames instantly and achieve the effect of continuous suppression; however, the following problems still exist. Taking the battery compartment where the battery is located as an example, when the battery experiences thermal runaway, a large amount of flammable gas escapes from the battery and enters the battery box. At this time, after the fire extinguishing device is activated, due to the gas production of the traditional aerosol fire extinguishing device The amount is large, and the aerosol fire extinguishing agent will quickly fill the entire battery box (that is, the battery compartment where the battery is located). In this process, only part of the flammable gas is pushed out of the battery compartment. More flammable gas is often pressed inside the battery and cannot be completely discharged because the positive pressure in the battery compartment is too large when the aerosol fire extinguishing device is sprayed. Therefore, when the aerosol fire extinguishing device is completed, the pressure in the battery compartment drops, and a large amount of flammable gas escapes from the inside of the battery again, and there is still a risk of re-ignition; in addition, the fire extinguishing device currently used needs to consider the situation of abnormal pressure increase during the fire extinguishing process, so it needs to have a pressure relief function; therefore, it is necessary to improve the traditional aerosol fire extinguishing device and design a fire extinguishing device that can be continuously and intermittently sprayed, so that the pressure of the battery box increases and decreases periodically, and has a pressure relief function, thereby solving the above problems.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide an intermittent spraying fire extinguishing device and method with a pressure relief structure, which can continuously perform an intermittent spraying process so that the pressure of the battery box increases and decreases periodically, which is beneficial to the complete discharge of the combustible gas inside the battery in the battery box, preventing the risk of re-ignition, and can also have a pressure relief function.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: an intermittent spraying fire extinguishing device with a pressure relief structure, comprising a shell and a gas-generating fire extinguishing agent arranged in the shell, a front cover is provided on the front side of the shell, a plurality of nozzles are opened on the surface of the front cover, the end face of the gas-generating fire extinguishing agent is connected to one end of the starting component, a piston is provided in the shell and slidingly matched with the piston, the piston is connected to the bottom of the front cover through a screw of a ball screw mechanism, the top of the screw is fixedly connected to the center of the rotating cover, liquid fire extinguishing agent is provided between the piston and the front cover, a spray hole is opened on the surface of the rotating cover, and when the rotating cover rotates, the spray hole and the nozzle periodically overlap and intersect; a pressure relief diaphragm is provided on the surface of some nozzles on the front cover surface, the piston comprises an outer ring piston located on the outside and an inner piston located on the inside, and a screw is passed through the inside of the inner piston.

[0006] Preferably, the ball screw mechanism includes a nut fixed inside the inner piston, the spiral groove area where the nut contacts the screw is filled with balls, and the top side of the screw is rotatably connected to the center of the front cover through a bearing.

[0007] Preferably, the rotating cover is located on the upper side of the front cover, and the connection strength between one side of the pressure relief diaphragm and one side of the nozzle is smaller than the connection strength between the other side of the pressure relief diaphragm and the other side of the nozzle.

[0008] Preferably, the central area of ​​the outer ring piston is interference fit with the outer side of the inner piston.

[0009] Preferably, the gas-generating fire extinguishing agent is a columnar structure formed by pressing aerosol generating agent powder, and the liquid fire extinguishing agent is perfluorohexanone fire extinguishing agent.

[0010] Preferably, the starting component is an electric ignition head or a thermal wire structure.

[0011] Preferably, the outer edge of the front cover is threadedly connected to the top of the shell, and the bottom of the shell is threadedly connected to the outer edge of the rear cover.

[0012] Preferably, the gas-generating fire extinguishing agent is located in the area where the back cover is located, and a silica gel layer is provided between the outer surface of the gas-generating fire extinguishing agent and the inner surface of the back cover.

[0013] Preferably, a guide rail is vertically provided on the inner side of the shell, and a guide groove is provided on the outer side of the outer ring piston, and the guide groove is in sliding fit with the guide rail.

[0014] In addition, the present invention also discloses a fire extinguishing method of the intermittent spraying type fire extinguishing device with a pressure relief structure, which comprises the following steps:

[0015] S1: When thermal runaway occurs in the battery box, the starting component ignites the gas-generating fire extinguishing agent, which generates gas;

[0016] S2: The outer ring piston of the airflow moves to the position of the front cover, and the ball screw mechanism causes the screw to rotate;

[0017] S3: When the screw rotates, the rotating cover is driven to rotate, so that the spray holes on the surface of the rotating cover and the spray holes on the surface of the front cover periodically overlap and intersect;

[0018] S4: When the nozzle hole and the nozzle outlet coincide, the liquid fire extinguishing agent is ejected from the nozzle. Under the action of the high temperature inside the battery box, it is converted into gas to extinguish the fire inside the battery box. When the nozzle hole and the nozzle outlet intersect, the shell is sealed and the pressure is held back. Finally, the above process is repeated periodically to achieve an intermittent spraying process, causing the pressure inside the battery box to increase and decrease periodically.

[0019] S5: When the pressure inside the battery box increases, the combustible gas diluted by the fire extinguishing material is pressed out from the gaps in the battery box. When the pressure inside the battery box decreases, the combustible gas inside the battery escapes and enters the battery box, and the above process is repeated in a cycle.

[0020] S6: When the spraying pressure of the liquid fire extinguishing agent in the shell increases abnormally, and the nozzle of the pressure relief diaphragm on the front cover is aligned with the spray hole on the surface of the rotating cover, one side of the pressure relief diaphragm flips outward from the spray hole, thereby blocking the rotating cover through the spray hole and stopping its rotation. At this time, high-pressure liquid fire extinguishing agent is continuously sprayed from the nozzle and the spray hole, and the first pressure relief process is carried out;

[0021] S7: When the rotating cover is stuck and stops rotating, the screw stops rotating, causing the piston to stop moving toward the position of the front cover. At this time, the pressure on the side of the piston close to the liquid fire extinguishing agent gradually decreases, while the pressure on the side close to the gas-generating fire extinguishing agent gradually increases due to continuous gas production. When the pressure increases to exceed the maximum static friction between the outer ring piston and the inner piston, the outer ring piston separates from the inner piston and moves upward. On the one hand, it can continue to push the remaining liquid fire extinguishing agent to be discharged from the nozzle and nozzle. On the other hand, the high-pressure gas generated by the gas-generating fire extinguishing agent also passes upward from the through hole exposed in the center area of ​​the outer ring piston and is ejected from the nozzle and nozzle for a second pressure relief process.

[0022] Beneficial effects of the present invention:

[0023] In the present invention, the airflow outer ring piston moves toward the position of the front cover, and the ball screw mechanism causes the screw to rotate; when the screw rotates, it drives the rotating cover to rotate, so that the spray holes on the surface of the rotating cover and the nozzles on the surface of the front cover periodically overlap and intersect, so that the liquid fire extinguishing agent can continue to perform an intermittent spraying process, so that the pressure of the battery box increases and decreases periodically, which is beneficial to the complete discharge of combustible gases inside the batteries in the battery box and prevents the risk of re-ignition; in addition, the present invention can realize primary and secondary pressure relief processes through the cooperation process between the pressure relief diaphragm, the outer ring piston and the inner piston, realize the pressure relief function, and ensure the safety of the fire extinguishing device during the fire extinguishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic diagram of the internal structure of an intermittent spraying fire extinguishing device with a pressure relief structure;

[0025] FIG2 is a schematic diagram of the three-dimensional structure of FIG1 ;

[0026] FIG3 is a schematic diagram of the top structure of the front cover in FIG1 ;

[0027] FIG4 is a schematic diagram of the cross-sectional structure of the piston in FIG1 cooperating with the inner wall of the housing. DETAILED DESCRIPTION

[0028] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0029] As shown in Figures 1 to 4, an intermittent spraying fire extinguishing device with a pressure relief structure includes a shell 1 and a gas-generating fire extinguishing agent 2 arranged in the shell 1. A front cover 3 is provided on the front side of the shell 1, and a plurality of nozzles 4 are opened on the surface of the front cover 3. The end face of the gas-generating fire extinguishing agent 2 is connected to one end of the starting component 5. A piston 7 is provided in the shell 1 and is slidably matched with the piston 7. The piston 7 is connected to the bottom of the front cover 3 through a screw 6.1 of a ball screw mechanism 6. The top of the screw 6.1 is fixedly connected to the center of a rotating cover 8. Liquid fire extinguishing agent 12 is provided between the piston 7 and the front cover 3. A spray hole 9 is opened on the surface of the rotating cover 8. When the rotating cover 8 rotates, the spray hole 9 and the nozzle 4 periodically overlap and intersect; a pressure relief diaphragm 15 is provided on the surface of some of the nozzles 4 on the surface of the front cover 3. The piston 7 includes an outer ring piston 7.1 located on the outside and an inner piston 7.2 located on the inside, and a screw 6.1 is passed through the inside of the inner piston 7.2.

[0030] Preferably, the ball screw mechanism 6 includes a nut 6.2 fixedly mounted within the inner piston 7.2. The spiral groove area where the nut 6.2 contacts the screw 6.1 is filled with balls. The top side of the screw 6.1 is rotatably connected to the center of the front cover 3 via a bearing. The ball screw mechanism 6 is a commonly used component in the mechanical field and includes a nut 6.2, a screw 6.1, a ball return pipe, balls, a dust cover, a deflector, and other components. Since the balls roll along the spiral groove area formed by the screw and nut during operation, the movement resistance is extremely small. Therefore, when the inner piston 7.2 is pressurized and moves upward, it drives the nut 6.2 upward, causing the screw 6.1 to rotate, thereby driving the rotating cover 8 to rotate. In addition, in the present invention, the bearing can effectively limit the screw 6.1, making its rotation process stable and reliable, while preventing the screw 6.1 from axial movement.

[0031] Preferably, the rotating cover 8 is located on the upper side of the front cover 3, and the connection strength between one side of the pressure relief diaphragm 15 and one side of the nozzle 4 is less than the connection strength between the other side of the pressure relief diaphragm 15 and the other side of the nozzle 4. With this design, when the nozzle 4 with the pressure relief diaphragm 15 provided on the surface of the front cover 3 is aligned with the nozzle 9 on the surface of the rotating cover 8, after being impacted by pressure, one side of the pressure relief diaphragm 15 will separate from the side of the nozzle 4, and then flip outward from the nozzle 9, thereby clamping the rotating cover 8 through the nozzle 9 and stopping its rotation. In addition, the surface of the rotating cover 8 can also be covered with a protective film to prevent moisture in the air from entering the shell 1 through the nozzle 9 and the nozzle 4, and to prevent the liquid fire extinguishing agent inside the shell 1 from leaking out; since the protective film itself is relatively thin, it is only used in the storage and transportation stages of the fire extinguishing device. When a fire occurs, the fire extinguishing agent can easily break through the protective film without affecting its normal spraying process.

[0032] Preferably, the center region of the outer ring piston 7.1 is interference-fitted with the outer side of the inner piston 7.2. In this embodiment, both the outer ring piston 7.1 and the inner piston 7.2 are made of rubber. A through hole is formed in the center region of the outer ring piston 7.1, into which the outer side of the inner piston 7.2 is squeezed to form an interference fit. The interior of the inner piston 7.2 is fixedly connected to the nut 6.2. Since the compression ratio of gas is greater than that of liquid, relative slippage between the outer ring piston 7.1 and the inner piston 7.2 is unlikely to occur during the normal spraying phase (i.e., the process in which the entire piston 7 moves upward to push the liquid fire extinguishing agent 12 out of the nozzle 4). Furthermore, static friction exists between the two, making slippage unlikely. Therefore, the outer ring piston 7.1 and the inner piston 7.2 move as a whole. In addition, a slot and boss connection can be further adopted between the interior of the inner piston 7.2 and the nut 6.2, which is less likely to cause relative slippage.

[0033] Preferably, the gas-generating fire extinguishing agent 2 is a cylindrical structure formed by pressing aerosol generating agent powder, and the liquid fire extinguishing agent 12 is perfluorohexanone fire extinguishing agent. The aerosol generating agent produces a large amount of gas when it burns, thereby moving the outer ring piston 7. Perfluorohexanone fire extinguishing agent, selected as liquid fire extinguishing agent 12, has a boiling point of 49°C and easily vaporizes due to the high temperature when a fire occurs, thereby changing the air pressure in the release area. Furthermore, this aerosol generating agent pressed into a cylindrical structure burns more slowly than a powdered aerosol generating agent, ensuring the continuous release of the fire extinguishing agent.

[0034] The aerosol generator is a prior art, for example, the invention patent with Chinese patent publication number CN101745195B discloses an "aging-resistant aerosol generator and its preparation process", which discloses that the aerosol generator is composed of an oxidant, a reducing agent, and a binder, wherein the oxidant is potassium nitrate, the binder is phenolic resin, and the reducing agent is melamine, and the mass percentages thereof are: potassium nitrate 74% to 80%, phenolic resin 8% to 15%, and the balance is melamine.

[0035] Its preparation method is:

[0036] Step 1: dissolving phenolic resin in ethanol to prepare a phenolic resin solution with a mass percentage concentration of 40% to 55%;

[0037] Step 2: Grind the oxidizing agent and reducing agent to a fineness of 80-200 standard mesh, mix them according to the required proportion, and sieve them through 80-200 mesh three times to make them evenly mixed;

[0038] Step 3: Then add the phenolic resin solution to the mixed powder, stir for 10 minutes, and then use a 40-mesh screen to force granulate. Then dry the agent in an environment with a temperature of 40°C and a relative humidity of less than 20% until the volatile components are less than 1%;

[0039] Step 4: Press the dried medicine under a pressure of 10 MPa to form an aerosol generating agent column structure.

[0040] Preferably, the starting component 5 is an electric ignition head or a thermal wire structure. When the starting component 5 is an electric ignition head structure, it can be connected to a fire detection device, which is a temperature sensor and / or a smoke sensor. When a fire, overheating, or the like occurs, the fire detection device detects the high temperature environment generated in the battery compartment due to the fire and sends a signal to the microprocessor, which controls the starting component 5 to ignite the gas-generating fire extinguishing agent 2. When the starting component 5 is a thermal wire structure, the thermal wire structure can be directly ignited when a fire occurs, and then the thermal wire directly ignites the gas-generating fire extinguishing agent 2, without the need for additional fire detection devices and other external equipment, which is simpler and less costly.

[0041] Preferably, the outer edge of the front cover 3 is threadedly connected to the top of the housing 1, and the bottom of the housing 1 is threadedly connected to the outer edge of the rear cover 10. Through this threaded connection method, the convenience of installation of the entire fire extinguishing device can be improved and the production process is convenient.

[0042] Preferably, the gas-generating fire extinguishing agent 2 is located in the area where the back cover 10 is located, and a silicone layer 11 is provided between the outer surface of the gas-generating fire extinguishing agent 2 and the inner surface of the back cover 10. The silicone layer 11 can effectively isolate the heat generated by the combustion of the gas-generating fire extinguishing agent 2, preventing the surface temperature of the back cover 10 and the housing 1 from being too high.

[0043] Preferably, a guide rail 13 is vertically provided on the inner side of the housing 1, and a guide groove 14 is provided on the outer side of the outer ring piston 7.1, and the guide groove 14 slides in cooperation with the guide rail 13. The sliding cooperation between the guide groove 14 and the guide rail 13 ensures the stability of the movement of the piston 7 and prevents the piston 7 from rotating radially.

[0044] Furthermore, in order to ensure that the contact area between the piston 7 and the screw 6.1 does not cause the perfluorohexanone liquid fire extinguishing agent to leak from the gap during the storage and transportation stage, a sealing ring can be added to the contact area between the lower end of the piston 7 and the screw 6.1 to effectively prevent the above-mentioned leakage.

[0045] In addition, the present invention also discloses a fire extinguishing method of the intermittent spraying type fire extinguishing device with a pressure relief structure, which comprises the following steps:

[0046] S1: When a battery in the battery box experiences thermal runaway, the starting component 5 ignites the gas-generating fire extinguishing agent 2, and the gas-generating fire extinguishing agent 2 generates gas;

[0047] S2: The airflow outer ring piston 7 moves to the position of the front cover 3, and the ball screw mechanism 6 causes the screw 6.1 to rotate;

[0048] S3: When the screw 6.1 rotates, it drives the rotating cover 8 to rotate, so that the spray holes 9 on the surface of the rotating cover 8 and the nozzles 4 on the surface of the front cover 3 periodically overlap and intersect;

[0049] S4: When the spray hole 9 and the nozzle 4 coincide with each other, the liquid fire extinguishing agent 12 is sprayed out from the nozzle 4, and is converted into gaseous state by the high temperature in the battery box to extinguish the fire in the battery box. When the spray hole 9 and the nozzle 4 are staggered, the shell 1 is sealed and a pressure-holding process is performed. Finally, the above process is repeated periodically to realize an intermittent spraying process, so that the pressure in the battery box increases and decreases periodically. In this step, when the fire extinguishing material is sprayed from the nozzle to extinguish the fire in the battery box, the gas inside the battery box increases, causing the pressure to increase. When the shell is sealed and a pressure-holding process is performed, the internal pressure of the battery box is released from the gap of the battery box itself, and the pressure decreases. Therefore, the pressure in the battery box increases and decreases periodically.

[0050] S5: When the pressure inside the battery box increases, the flammable gas diluted by the fire extinguishing substance is pressed out from the gaps in the battery box. When the pressure inside the battery box decreases, the flammable gas inside the battery escapes and enters the battery box, and the above process is repeated. Through this low-pressure and high-pressure reciprocating cycle, the flammable gas generated in the battery can eventually be diluted by the fire extinguishing substance and continuously discharged from the battery compartment, completing the entire fire extinguishing process and effectively preventing the risk of re-ignition.

[0051] S6: When the spraying pressure of the liquid fire extinguishing agent 12 in the housing 1 increases abnormally, and the nozzle 4 of the pressure relief diaphragm 15 provided on the surface of the front cover 3 is aligned with the nozzle hole 9 on the surface of the rotating cover 8, one side of the pressure relief diaphragm 15 is flipped outward from the nozzle hole 9, thereby blocking the rotating cover 8 through the nozzle hole 9 and stopping its rotation. At this time, the high-pressure liquid fire extinguishing agent 12 is continuously sprayed from the nozzle 4 and the nozzle hole 9, and the first pressure relief process is carried out;

[0052] S7: When the rotating cover 8 is stuck and stops rotating, the screw 6.1 stops rotating, causing the piston 7 to stop moving toward the position of the front cover 3. At this time, the pressure on the side of the piston close to the liquid fire extinguishing agent 12 gradually decreases, while the pressure on the side close to the gas-generating fire extinguishing agent 2 gradually increases due to continuous gas production. When the pressure increases to exceed the maximum static friction between the outer ring piston 7.1 and the inner piston 7.2, the outer ring piston 7.1 separates from the inner piston 7.2 and moves upward. On the one hand, it can continue to push the remaining liquid fire extinguishing agent 12 to be discharged from the nozzle 4 and the nozzle hole 9. On the other hand, the high-pressure gas generated by the gas-generating fire extinguishing agent 2 also passes upward from the through hole exposed in the central area of ​​the outer ring piston 7.1 and is ejected from the nozzle 4 and the nozzle hole 9 to perform a second pressure relief process.

[0053] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The embodiments and features in the embodiments of this application may be arbitrarily combined with each other unless they conflict. The scope of protection of the present invention shall be the technical solutions described in the claims, including equivalent alternatives to the technical features of the technical solutions described in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. An intermittent spraying type fire extinguishing device with a pressure relief structure, comprising a housing (1) and a gas-generating fire extinguishing agent (2) arranged in the housing (1), a front cover (3) being arranged on the front side of the housing (1), a plurality of nozzles (4) being arranged on the surface of the front cover (3), an end surface of the gas-generating fire extinguishing agent (2) being connected to one end of a starting component (5), characterized in that: A piston (7) is provided in the housing (1) and is slidably matched with the housing (1). The piston (7) is connected to the bottom of the front cover (3) through a screw (6.1) of a ball screw mechanism (6). The top of the screw (6.1) is fixedly connected to the center of a rotating cover (8). A liquid fire extinguishing agent (12) is provided between the piston (7) and the front cover (3). A spray hole (9) is provided on the surface of the rotating cover (8). When the rotating cover (8) rotates, the spray hole (9) and the nozzle (4) overlap and intersect periodically. A pressure relief diaphragm (15) is provided on the surface of some nozzles (4) on the surface of the front cover (3). The piston (7) comprises an outer ring piston (7.1) located outside and an inner piston (7.2) located inside. The screw (6.1) is passed through the inner piston (7.2).

2. An intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The ball screw mechanism (6) comprises a nut (6.2) fixed inside the inner piston (7.2), the spiral groove area where the nut (6.2) contacts the screw rod (6.1) is filled with balls, and the top side of the screw rod (6.1) is rotatably connected to the center of the front cover (3) via a bearing.

3. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The rotating cover (8) is located on the upper side of the front cover (3), and the connection strength between one side of the pressure relief diaphragm (15) and one side of the nozzle (4) is smaller than the connection strength between the other side of the pressure relief diaphragm (15) and the other side of the nozzle (4).

4. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The central area of ​​the outer ring piston (7.1) is interference fit with the outer side of the inner piston (7.2).

5. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The gas-generating fire extinguishing agent (2) is a columnar structure formed by pressing aerosol generating agent powder, and the liquid fire extinguishing agent (12) is a perfluorohexanone fire extinguishing agent.

6. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The starting component (5) is an electric ignition head or a thermal wire structure.

7. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: The outer edge of the front cover (3) is threadedly connected to the top of the shell (1), and the bottom of the shell (1) is threadedly connected to the outer edge of the rear cover (10).

8. An intermittent spraying fire extinguishing device with a pressure relief structure according to claim 7, characterized in that: The gas-generating fire extinguishing agent (2) is located in the area where the rear cover (10) is located, and a silica gel layer (11) is provided between the outer surface of the gas-generating fire extinguishing agent (2) and the inner surface of the rear cover (10).

9. The intermittent spraying fire extinguishing device with a pressure relief structure according to claim 1, characterized in that: A guide rail (13) is also vertically arranged on the inner side of the housing (1), and a guide groove (14) is provided on the outer side of the outer ring piston (7.1), wherein the guide groove (14) is in sliding cooperation with the guide rail (13).

10. A fire extinguishing method using the intermittent spraying type fire extinguishing device with a pressure relief structure according to any one of claims 1 to 9, characterized in that: It includes the following steps: S1: When a battery in the battery box experiences thermal runaway, the starting component (5) ignites the gas-generating fire extinguishing agent (2), and the gas-generating fire extinguishing agent (2) generates gas; S2: The airflow outer ring piston (7) moves toward the position of the front cover (3), and the ball screw mechanism (6) causes the screw (6.1) to rotate. S3: When the screw (6.1) rotates, it drives the rotating cover (8) to rotate, so that the spray holes (9) on the surface of the rotating cover (8) and the spray ports (4) on the surface of the front cover (3) periodically overlap and intersect; S4: When the spray hole (9) and the nozzle (4) overlap, the liquid fire extinguishing agent (12) is sprayed out from the nozzle (4) and, under the action of the high temperature in the battery box, is converted into a gaseous state to extinguish the fire in the battery box. When the spray hole (9) and the nozzle (4) intersect, the housing (1) is sealed and a pressure holding process is performed. Finally, the above process is repeated periodically to realize an intermittent spraying process, so that the pressure in the battery box increases and decreases periodically. S5: When the pressure in the battery box increases, the combustible gas diluted by the fire extinguishing material is pressed out from the gap of the battery box. When the pressure in the battery box decreases, the combustible gas inside the battery escapes and enters the battery box, and the above process is repeated in a cycle. S6: When the spraying pressure of the liquid fire extinguishing agent (12) in the housing (1) increases abnormally, and the nozzle (4) of the pressure relief diaphragm (15) provided on the surface of the front cover (3) is aligned with the spray hole (9) on the surface of the rotating cover (8), one side of the pressure relief diaphragm (15) is turned over to the outside of the spray hole (9), thereby blocking the rotating cover (8) through the spray hole (9) to stop its rotation. At this time, the high-pressure liquid fire extinguishing agent (12) is continuously sprayed from the nozzle (4) and the spray hole (9), and the first pressure relief process is carried out; S7: When the rotating cover (8) is stuck and stops rotating, the screw (6.1) stops rotating, causing the piston (7) to stop moving toward the position of the front cover (3). At this time, the pressure on the side of the piston close to the liquid fire extinguishing agent (12) gradually decreases, while the pressure on the side close to the gas-generating fire extinguishing agent (2) gradually increases due to the continuous gas production. When the pressure increases to exceed the maximum static friction between the outer ring piston (7.1) and the inner piston (7.2), the outer ring piston (7.1) separates from the inner piston (7.2) and moves upward, which can continue to push the remaining liquid fire extinguishing agent (12) from the nozzle (4) and the nozzle (5). On the other hand, the high-pressure gas generated by the gas-generating fire extinguishing agent (2) also passes upward from the through hole exposed in the central area of ​​the outer ring piston (7.1) and is ejected from the nozzle (4) and the nozzle hole (9) to perform a second pressure relief process.

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