Explosion-proof valve system for battery pack and control method thereof

Abstract

The application discloses a kind of explosion-proof valve system and its control method for battery pack, explosion-proof valve system includes explosion-proof valve body, exhaust fan and controller, explosion-proof valve body is set to the air outlet of battery pack;Exhaust fan is set to the outside of explosion-proof valve body, exhaust fan is connected with explosion-proof valve body by limiting component and hinge component;Wherein, limiting component is equipped with weak area, in extreme situation such as exhaust fan itself failure influence exhaust, weak area is adapted to fracture under the action of air pressure, and makes exhaust fan overturn relative to explosion-proof valve body;Controller is used to control exhaust fan operation according to the monitoring data of battery pack management system.The application can actively intervene in early heat runaway, reduce the risk of heat spread;Through multi-dimensional signal coupling early warning strategy, reduce the risk of false alarm, improve the reliability of system response;It can realize automatic regulation and control under multiple scenes, multiple working conditions, intelligently grade protection for thermal safety, and also consider the electrical safety protection in package.

Description

Technical Field

[0001] This application relates to the field of thermal runaway protection technology for power batteries, and in particular to an explosion-proof valve system for battery packs and its control method. Background Technology

[0002] As a critical pressure relief component in battery systems during thermal runaway, the performance of explosion-proof valves directly determines the effectiveness of thermal propagation prevention.

[0003] Currently, the mainstream explosion-proof valves include piston-spring type and pin-type explosion-proof valves. Both types are passive explosion-proof valves. When thermal runaway occurs, the gas pressure inside the battery pack reaches a set threshold, the burst structure opens, and the pressure relief channel is fully opened, achieving passive pressure relief. However, this type of passive pressure relief valve has inherent defects such as trigger lag and low venting efficiency, making it impossible to intervene in the early stages of thermal runaway. To improve venting efficiency, some explosion-proof valves have added flow channels, expanded pressure relief channels, and reduced burst pressure, but they are still essentially passively triggered and fail to effectively solve the problem of early venting lag in thermal runaway. Furthermore, reducing the burst pressure increases the risk of battery pack sealing failure.

[0004] In related technologies, some explosion-proof valves integrate a thermoplastic trigger element. When the temperature reaches a threshold, the thermoplastic element melts, opening the valve cover to achieve early pressure relief. However, this type of explosion-proof valve is highly susceptible to leakage triggering. Moreover, under high temperature and humidity conditions or during gradual aging, the thermoplastic element itself is prone to deformation or changes in its physical properties, leading to a reduction or loss of the effectiveness of the triggering mechanism, which in turn hinders timely pressure relief in the event of thermal runaway. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. Therefore, the purpose of this application is to propose an explosion-proof valve system and its control method for battery packs, aiming to solve the problems of delayed pressure relief protection and low triggering reliability of explosion-proof valves.

[0006] In a first aspect, this application proposes an explosion-proof valve system for a battery pack. The explosion-proof valve system includes an explosion-proof valve body, an exhaust fan, and a controller. The explosion-proof valve body is disposed at the air outlet of the battery pack. The exhaust fan is disposed on the outside of the explosion-proof valve body and is coaxially arranged with the explosion-proof valve body. The exhaust fan and the explosion-proof valve body are connected by a limiting component and a hinge component. The limiting component and the hinge component are spaced apart circumferentially. The limiting component has a weak area, which is suitable for breaking under the action of air pressure inside the battery pack, causing the exhaust fan to flip relative to the explosion-proof valve body. The controller is connected to the battery pack management system and the exhaust fan, and is used to control the operation of the exhaust fan according to the monitoring data of the battery pack management system.

[0007] The explosion-proof valve system of this application achieves active pressure relief through exhaust fan extraction, enabling proactive intervention in the early stages of thermal runaway. This dissipates heat before it accumulates significantly, reducing the risk of thermal propagation within the battery pack and resolving the issue of delayed pressure relief protection. A multi-dimensional signal coupling early warning strategy allows for cross-verification of the battery pack's internal state, avoiding misjudgments and missed detections of thermal runaway conditions. This addresses the limitations of application scenarios and operating conditions, high risks of false alarms and missed detections, and low reliability. Furthermore, the integrated design of the exhaust fan and explosion-proof valve body improves adaptability and compatibility, allowing compatibility with existing explosion-proof valve assembly interfaces and resolving issues of large modifications, space occupation, and increased installation and maintenance costs. The connection structure between the exhaust fan and the explosion-proof valve body incorporates a weak point, preventing the exhaust fan from blocking the valve's exhaust passage and enhancing safety redundancy.

[0008] According to some embodiments of this application, the outer diameter of the exhaust fan is larger than the outer diameter of the explosion-proof valve body, so as to form an annular overflow gap between the exhaust fan and the explosion-proof valve body.

[0009] According to some embodiments of this application, the battery pack management system includes a temperature monitoring module, a humidity monitoring module, an air pressure monitoring module, a smoke concentration monitoring module, and a voltage monitoring module, for monitoring the temperature, humidity, air pressure, and smoke concentration inside the battery pack, as well as the voltage of the battery pack, respectively.

[0010] According to some embodiments of this application, a protective member is provided on the outside of the exhaust fan, and the flow area of ​​the protective member is greater than or equal to 80% of the cross-sectional area.

[0011] According to some embodiments of this application, the limiting component includes a connecting pin and an actuator, wherein the connecting pin connects the exhaust fan and the explosion-proof valve body and has a weak area; the actuator is connected to the connecting pin and is used to force the weak area to break.

[0012] According to some embodiments of this application, the explosion-proof valve body is provided with a shape memory alloy valve core, which is used to adjust the flow area of ​​the pressure relief channel according to the temperature.

[0013] According to some embodiments of this application, the pressure relief channel outlet of the explosion-proof valve body is provided with an ejector nozzle.

[0014] Secondly, this application proposes a control method based on the above-mentioned explosion-proof valve system for battery packs, comprising: Obtain the safety parameters of the battery pack. Determine the thermal conditions of the battery pack based on safety parameters; Control the operation of the exhaust fan based on thermal conditions and safety parameters.

[0015] The control method for the explosion-proof valve system of the battery pack according to this application utilizes a multi-dimensional signal coupling strategy to cross-verify and determine the true state inside the battery pack, avoiding misjudgments and omissions in thermal runaway states, thus improving the accuracy of thermal runaway prediction and providing a more comprehensive and reliable reflection of the true internal state of the battery pack. Through graded identification of thermal conditions, refined risk management of the battery pack is achieved, accurately distinguishing the severity of risks and avoiding over- or delayed responses. By controlling the exhaust fan in stages and dynamically adapting, both energy saving and protective effects are balanced. Early intervention and active protection are achieved through auxiliary exhaust cooling during the weak thermal runaway stage, reducing the hazards of thermal runaway.

[0016] According to some embodiments of this application, safety parameters include the internal temperature, humidity, air pressure, smoke concentration, and voltage of the battery pack. Thermal operating conditions include non-thermal runaway operating conditions, weak thermal runaway operating conditions, and strong thermal runaway operating conditions. Determining the thermal operating condition of the battery pack based on the safety parameters includes: determining the battery pack's operating condition as a non-thermal runaway operating condition in response to the temperature, air pressure, smoke concentration, and voltage all meeting preset safety conditions; determining the battery pack's operating condition as a weak thermal runaway operating condition in response to at least two of the temperature, air pressure, smoke concentration, and voltage meeting a first preset thermal runaway condition; and determining the battery pack's operating condition as a strong thermal runaway operating condition in response to at least one of the temperature, air pressure, smoke concentration, and voltage meeting a second preset thermal runaway condition.

[0017] According to some embodiments of this application, controlling the operation of an exhaust fan based on thermal conditions includes: controlling the exhaust fan to operate at a first speed based on air pressure and humidity in response to the battery pack being in a non-thermal runaway condition; controlling the exhaust fan to operate at a second speed based on safety parameters in response to the battery pack being in a weak thermal runaway condition; and controlling the exhaust fan to operate at maximum power in response to the battery pack being in a strong thermal runaway condition.

[0018] The explosion-proof valve system and control method for the battery pack according to this application have the following technical advantages compared with the prior art: (1) The exhaust fan and the explosion-proof valve body are integrated into a coaxial unit. The active air extraction by the exhaust fan can improve the exhaust pressure relief efficiency, making the exhaust pressure relief and heat dissipation efficiency more than twice as high, and delaying the spread of heat. At the same time, the pressure relief is safer. The negative pressure environment formed by the exhaust fan can prevent the backflow of external oxygen and reduce the intensity of thermal runaway combustion by more than 30%. In addition, the integrated structure can be directly installed on the existing battery pack interface, with strong compatibility and adaptability, solving the problems of large modification, large space occupation, and increased installation and maintenance costs.

[0019] (2) A three-in-one design of “structural integration-functional coordination-intelligent control” has been formed. By integrating the judgment logic of the BMS system, a multi-dimensional signal coupling early warning strategy is adopted to fully identify the actual state inside the battery pack, thereby differentiating the operation of the exhaust fan, avoiding the risk of missed triggering and false triggering, and solving the problems of limited application scenarios and working conditions, high risk of missed and false alarms, and low reliability.

[0020] (3) Based on multi-dimensional signal control of exhaust fan operation, it covers ventilation and dehumidification under non-thermal runaway conditions, and quickly balances the pressure difference inside and outside the battery pack; it realizes active intervention in weak thermal runaway conditions or early stage of thermal runaway (i.e., the early stage when pressure and temperature have not reached the thermal runaway threshold), actively pumping air to dissipate heat, avoiding heat accumulation inside the battery pack, reducing the probability of later thermal spread by more than 35%, and effectively delaying thermal spread; it realizes enhanced air pumping to prevent backflow when rapid pressure relief is required under strong thermal runaway conditions; this application realizes the intelligent upgrade of the explosion-proof valve system from threshold-triggered passive response to early active identification and early prevention, the control threshold and exhaust fan power can be flexibly configured in stages by software, and can be adapted to cell systems and battery pack systems with different energy densities and thermal runaway intensities without adjusting the mechanical structure, and can cope with different scenarios and working conditions, with stronger applicability.

[0021] (4) By setting a weak area in the limiting components between the exhaust fan and the explosion-proof valve body, the safety and reliability of the system under extreme working conditions can be improved. Even if the exhaust fan itself fails, the pressure relief channel can still be kept open, thus improving the safety protection performance.

[0022] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0023] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is an assembly diagram of the explosion-proof valve system and battery pack according to some embodiments of this application; Figure 2 This is a schematic diagram of the structure of an explosion-proof valve system according to some embodiments of this application; Figure 3 This is a schematic diagram of the structure of an explosion-proof valve system according to other embodiments of this application; Figure 4 This is a flowchart illustrating the control method of an explosion-proof valve system according to some embodiments of this application.

[0024] Figure label: Battery pack 1; Explosion-proof valve body 2; Exhaust fan 3; Limiting component 4; hinge component 5; battery pack management system 6; protective component 7. Detailed Implementation

[0025] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0026] The following is for reference. Figures 1-3 This application describes an explosion-proof valve system according to an embodiment of the present application.

[0027] In a first aspect, this application proposes an explosion-proof valve system for a battery pack. The explosion-proof valve system includes an explosion-proof valve body 2, an exhaust fan 3, and a controller. The explosion-proof valve body 2 is disposed at the air outlet of the battery pack 1. The exhaust fan 3 is disposed on the outside of the explosion-proof valve body 2 and is coaxially disposed with the explosion-proof valve body 2. The exhaust fan 3 and the explosion-proof valve body 2 are connected by a limiting component 4 and a hinge component 5. The limiting component 4 and the hinge component 5 are spaced apart circumferentially. The limiting component 4 has a weak area, which is suitable for breaking under the action of air pressure inside the battery pack 1, causing the exhaust fan 3 to flip relative to the explosion-proof valve body 2. The controller is connected to the battery pack management system 6 and the exhaust fan 3, and is used to control the operation of the exhaust fan 3 according to the monitoring data of the battery pack management system 6.

[0028] The explosion-proof valve body 2 is located at the air outlet of the battery pack 1. During normal operation, it provides ventilation and heat dissipation. In the event of thermal runaway causing internal pressure to reach a threshold, it bursts open the pressure relief channel for efficient pressure relief and heat dissipation. The exhaust fan 3 is coaxially mounted with the explosion-proof valve body 2, utilizing negative pressure suction to enhance ventilation and heat dissipation. The cooling efficiency of the explosion-proof valve system can be adjusted by controlling the speed of the exhaust fan 3. Specifically, when the battery pack 1 is at a low temperature and there is no risk of thermal runaway, the exhaust fan 3 can operate at a low speed to actively balance the pressure difference between the inside and outside of the battery pack 1 and promptly remove moisture, preventing condensation inside the battery pack 1 and avoiding safety risks to the insulation of electrical components. When the battery pack 1 is at a high temperature and there is a risk of thermal runaway, the speed of the exhaust fan 3 can be increased to proactively extract high-temperature flue gas in the early stages, accelerating heat dissipation, reducing the temperature and flammable gas concentration inside the battery pack 1, and inhibiting heat spread.

[0029] Furthermore, such as Figure 1 , Figure 2As shown, the exhaust fan 3 and the explosion-proof valve body 2 adopt a coaxial nested integrated design, which can reduce airflow loss caused by pipeline connections and simplify the structure. The exhaust fan 3 is located on the outside of the explosion-proof valve body 2, without requiring any changes to the structure of the battery pack 1 enclosure. This design offers high adaptability, low installation difficulty and cost, and improves the space utilization of the battery pack 1. The integrated structure of the exhaust fan 3 and the explosion-proof valve body 2, with the entire assembly installed on the outside of the battery pack 1, allows for maintenance and replacement without disassembling the battery pack 1, greatly reducing maintenance, adaptation, and deployment costs.

[0030] Furthermore, the exhaust fan 3 is connected to the explosion-proof valve body 2 via a limiting assembly 4 and a hinge assembly 5. The hinge assembly 5 connects the exhaust fan 3 and the explosion-proof valve body 2, allowing the exhaust fan 3 to rotate relative to the explosion-proof valve body 2. The limiting assembly 4 locks the exhaust fan 3 and the explosion-proof valve body 2, restricting the exhaust fan 3's rotational freedom relative to the explosion-proof valve body 2. The limiting assembly 4 and the hinge assembly 5 are spaced apart circumferentially, allowing the exhaust fan 3 to be stably mounted on the outside of the explosion-proof valve body 2 under normal operating conditions, thus serving the function of exhausting and dissipating heat.

[0031] Furthermore, in the event of thermal runaway of battery pack 1, the exhaust fan 3 is located at the end of the exhaust channel. A malfunction in this fan could affect or obstruct exhaust pressure relief. To address this, the limiting component 4 of this application has a weak point, which is an automatic avoidance structure and is prone to breakage. Its fracture strength threshold can be set according to the pressure relief requirements under extreme conditions such as thermal runaway or exhaust fan 3 malfunction. Under extreme conditions such as thermal runaway or exhaust fan 3 malfunction affecting exhaust, as the thermal runaway pressure of battery pack 1 accumulates, the pressure difference between the inside and outside of battery pack 1 gradually increases. When the thrust acting on the surface of exhaust fan 3 reaches the fracture strength threshold of the weak point, the weak point breaks, allowing exhaust fan 3 to rotate relative to the explosion-proof valve body 2, thereby automatically avoiding the pressure relief channel and achieving rapid pressure relief. In this way, exhaust fan 3 will not block the exhaust channel and will not affect the pressure relief effect of the explosion-proof valve body 2 itself. By setting a weak point, an effective preventative measure is provided against exhaust fan 3 malfunction. When insufficient airflow and accumulated internal and external pressure difference occur due to reasons such as exhaust fan 3 malfunction, the exhaust fan 3 can be bypassed from the pressure relief channel by breaking the weak area. After the limit component 4 breaks, the exhaust fan 3 rotates relative to the explosion-proof valve body 2, and the hinge component 5 can still keep the exhaust fan 3 connected to the explosion-proof valve body 2, preventing it from falling off or splashing, and ensuring system safety.

[0032] The controller connects the battery pack management system (BMS) 6 and the exhaust fan 3. The BMS can collect real-time data on the voltage of the battery pack 1, as well as the internal temperature, humidity, air pressure, and smoke concentration. This monitoring data characterizes the operating status of the battery pack 1, thereby determining whether there is a risk of thermal runaway. Based on the BMS monitoring data, the controller controls the operation of the exhaust fan 3 and adjusts its speed to achieve effective heat dissipation and proactively prevent thermal runaway of the battery pack 1.

[0033] According to the explosion-proof valve system of this application, active pressure relief can be achieved by evacuating air through an exhaust fan, allowing for proactive intervention in the early stages of thermal runaway. This dissipates heat before it has a chance to accumulate significantly, reducing the risk of thermal propagation in battery pack 1 and solving the problem of delayed pressure relief protection. Through a multi-dimensional signal coupling early warning strategy, the true state within battery pack 1 can be determined through cross-verification of multi-dimensional signals, avoiding misjudgments and missed detections of thermal runaway states. This solves the problems of limited application scenarios and operating conditions, high risk of false and missed alarms, and low reliability. Simultaneously, the integrated design of the exhaust fan 3 and the explosion-proof valve body 2 improves adaptability and compatibility, allowing compatibility with existing explosion-proof valve assembly interfaces and solving the problems of large modifications, space occupation, and increased installation and maintenance costs. The connection structure between the exhaust fan 3 and the explosion-proof valve body 2 is designed with a weak point, which can solve the problem of the exhaust fan 3 blocking the exhaust passage of the explosion-proof valve body 2, improving safety redundancy performance.

[0034] In some embodiments, the exhaust fan 3 integrates an intelligent electronic control unit, which is connected to the BMS within the battery pack 1, enabling communication and interaction. This embodiment as a whole constitutes an integrated intelligent electronic explosion-proof valve system, offering greater adaptability to various scenarios and operating conditions.

[0035] According to some embodiments of this application, the outer diameter of the exhaust fan 3 is larger than the outer diameter of the explosion-proof valve body 2, so as to form an annular overflow gap between the exhaust fan 3 and the explosion-proof valve body 2. In this embodiment, as... Figure 1 As shown, the outer diameter of the exhaust fan 3 is larger than the outer diameter of the explosion-proof valve body 2, which avoids the exhaust fan 3's housing from obstructing the pressure relief channel, allowing the flow surface of the exhaust fan 3 to cover the pressure relief channel. An annular overflow gap is formed between the inner peripheral wall of the exhaust fan 3's housing and the outer peripheral wall of the explosion-proof valve body 2, increasing the flow area. This embodiment, by enlarging the diameter of the exhaust fan 3, increases the redundancy of the exhaust flow in the entire integrated system, ensuring that the total exhaust flow of the explosion-proof valve system is not less than the exhaust flow of the explosion-proof valve body 2. Even if the exhaust fan 3 is stuck, sufficient exhaust flow can still be guaranteed through the annular overflow gap formed by the enlarged diameter.

[0036] According to some embodiments of this application, the battery pack management system 6 includes a temperature monitoring module, a humidity monitoring module, an air pressure monitoring module, a smoke concentration monitoring module, and a voltage monitoring module, for monitoring the temperature, humidity, air pressure, and smoke concentration inside the battery pack 1, as well as the voltage of the battery pack 1. In this embodiment, the temperature monitoring module is used to monitor the temperature inside the battery pack 1; the humidity monitoring module is used to monitor the humidity inside the battery pack 1; the air pressure monitoring module is used to monitor the air pressure inside the battery pack 1; the smoke concentration monitoring module is used to monitor the smoke concentration inside the battery pack 1; and the voltage monitoring module is used to monitor the voltage of the battery pack 1. By monitoring the temperature, humidity, air pressure, and smoke concentration inside the battery pack 1, as well as the voltage of the battery pack 1, the BMS can establish a control basis for the operation of the exhaust fan 3. Through multi-dimensional signal coupling, it controls the operation of the exhaust fan 3 to achieve proactive prevention and accelerated heat dissipation.

[0037] According to some embodiments of this application, a protective member 7 is provided on the outer side of the exhaust fan 3, and the flow area of ​​the protective member 7 is greater than or equal to 80% of the cross-sectional area. In this embodiment, such as Figure 3 As shown, by setting up the protective component 7, external sand, dust, and other foreign objects can be prevented from intruding and causing the exhaust fan 3 to become stuck. The flow area of ​​the protective component 7 is greater than or equal to 80% of its cross-sectional area. This larger flow area effectively reduces the obstruction of airflow by the protective component 7, ensuring that the exhaust fan 3 can discharge sufficient air to remove the heat generated by the battery pack 1 during operation and prevent thermal runaway due to overheating. The protective component 7 can adopt a protective grille, honeycomb mesh, or other protective structure to achieve both ventilation and prevention of external foreign object intrusion.

[0038] According to some embodiments of this application, the limiting component 4 includes a connecting pin and an actuator. The connecting pin connects the exhaust fan 3 and the explosion-proof valve body 2 and has a weak point. The actuator connects to the connecting pin and forces the weak point to break. In this embodiment, the connecting pin connects the exhaust fan 3 and the explosion-proof valve body 2, limiting the rotation of the exhaust fan 3 relative to the explosion-proof valve body 2, so that the exhaust fan 3 remains coaxial with the explosion-proof valve body 2 under normal operating conditions to achieve air extraction and heat dissipation. The connecting pin has the aforementioned weak point, which is a fragile structure, and automatically avoids active breakage. The fracture strength threshold of the weak point can be set according to the pressure relief requirements under extreme conditions such as severe thermal runaway or exhaust fan 3 failure. The actuator connects to the connecting pin and forces the weak point to break, thereby allowing the exhaust fan 3 to rotate relative to the explosion-proof valve body 2, thereby avoiding the pressure relief channel and preventing blockage or obstruction. This embodiment achieves active avoidance of the exhaust fan 3 by setting a connecting pin and an actuator. In the event of exhaust fan 3 failure or extreme thermal runaway, the connecting pin can be disconnected in a timely manner, allowing the exhaust fan 3 to rotate relative to the explosion-proof valve body 2 and actively avoid the pressure relief channel, so as to ensure that the explosion-proof valve body 2 can relieve pressure efficiently and safely.

[0039] In some embodiments, one end of the connecting pin is connected to the outer peripheral wall of the exhaust fan 3, and the other end is connected to the existing mounting hole of the explosion-proof valve body 2 housing.

[0040] In some embodiments, the intelligent electronic control unit of the exhaust fan 3 has a built-in current detection unit, speed detection unit and pressure detection unit, which can realize triple fault monitoring of current sampling, speed feedback and differential pressure verification. It can accurately identify software and hardware faults. In extreme cases such as excessive differential pressure or abnormal speed, it can immediately cut off the power supply to the fan and at the same time control the actuator to disconnect the connecting pin to prevent the exhaust fan 3 from affecting the exhaust pressure relief.

[0041] In this application, the exhaust fan 3 is integrated with the aforementioned hinge assembly 5 and limiting assembly 4. Compared to a separate active exhaust solution, this application is compatible with existing explosion-proof valve mounting holes, allowing for direct installation and replacement without modifying the battery pack 1 structure; it can reduce more than two additional sealing points, reducing the risk of leakage from the battery pack 1 casing by 50% and lowering the implementation cost by more than 40%. This application adopts an integrated design, eliminating the need for additional external gas pipelines and avoiding the problem of decreased pressure relief efficiency caused by component aging and increased air resistance. Furthermore, the controllable flip design avoids the risk of the exhaust fan 3 malfunctioning and blocking the exhaust pressure relief channel under extreme conditions. This application can reduce the installation and maintenance costs of the system throughout its entire lifecycle by more than 30%.

[0042] In some embodiments, the explosion-proof valve body 2 of this application may be driven and triggered by an intelligent electronic control unit, and its valve core may be made of aluminum alloy; or it may be triggered by a passive phase change, and its valve core may be made of phase change material.

[0043] According to some embodiments of this application, the explosion-proof valve body 2 is provided with a shape memory alloy valve core, which is used to adjust the flow area of ​​the pressure relief channel according to the temperature. In this embodiment, the shape memory alloy valve core is a passive phase change triggered valve core, which can reversibly change its shape in response to temperature changes, thereby controlling the opening and closing of the pressure relief channel. The triggering of the shape memory alloy valve core in this embodiment can be directly achieved by the ambient temperature of the abnormally heated battery pack 1, enabling the valve to achieve precise and rapid temperature control response to thermal runaway. Moreover, the shape memory alloy valve core can achieve active pre-pressure relief through a mechanical structure, which can also reduce costs. At the same time, this embodiment, combined with the exhaust fan 3, can further improve the exhaust heat dissipation efficiency.

[0044] According to some embodiments of this application, the outlet of the pressure relief channel of the explosion-proof valve body 2 is provided with an ejector nozzle. In this embodiment, the ejector nozzle is integrated on the outside of the exhaust channel, which can utilize the kinetic energy of the pre-released high-pressure airflow to create a negative pressure effect and increase the exhaust speed.

[0045] In some embodiments, the ejector nozzle is a passive jet ejector nozzle, which can increase the exhaust speed by 1.5 times, achieving the air extraction effect of the exhaust fan 3, and does not require an external power supply.

[0046] In other embodiments, the ejector nozzle is a high-pressure ejector nozzle, connected to the existing high-pressure air source of the vehicle or energy storage system via a thin-diameter pipe, eliminating the need for an additional power unit. Only a solenoid valve and control unit are installed on the air source side. When active venting is required, the BMS controls the solenoid valve to open, allowing high-pressure airflow to pass through the ejector nozzle and create negative pressure, extracting gas from inside the battery pack 1. The extraction efficiency can be flexibly controlled by adjusting the air source pressure. Opening the solenoid valve under depressurization conditions enhances venting and prevents backflow of air. Furthermore, the flow area of ​​the ejector nozzle is completely identical to the original depressurization channel, ensuring that even if the solenoid valve fails, the passive depressurization function of the explosion-proof valve body 2 will not be affected.

[0047] Below, please refer to the appendix. Figure 4 This application describes the control method for the explosion-proof valve.

[0048] Secondly, this application proposes a control method based on the above-mentioned explosion-proof valve system for battery packs, comprising: S1. Obtain the safety parameters of the battery pack.

[0049] The safety parameters include the internal temperature, humidity, air pressure, smoke concentration, and voltage of the battery pack. The battery pack's electronic management system (BMS) can collect the battery pack's voltage, internal temperature, humidity, air pressure, and smoke concentration in real time; these safety parameters characterize the battery pack's operating status.

[0050] In some embodiments, the battery pack includes a temperature monitoring module, a humidity monitoring module, an air pressure monitoring module, a smoke concentration monitoring module, and a voltage monitoring module. The temperature monitoring module monitors the temperature inside the battery pack; the humidity monitoring module monitors the humidity inside the battery pack; the air pressure monitoring module monitors the air pressure inside the battery pack; the smoke concentration monitoring module monitors the smoke concentration inside the battery pack; and the voltage monitoring module monitors the voltage of the battery pack. The BMS is connected to the temperature monitoring module, humidity monitoring module, air pressure monitoring module, smoke concentration monitoring module, and voltage monitoring module to collect real-time data on the temperature, humidity, air pressure, smoke concentration, and voltage of the battery pack, as well as other safety parameters.

[0051] S2. Determine the thermal conditions of the battery pack based on safety parameters.

[0052] According to some embodiments of this application, safety parameters include the internal temperature, humidity, air pressure, smoke concentration, and voltage of the battery pack. Thermal operating conditions include non-thermal runaway operating conditions, weak thermal runaway operating conditions, and strong thermal runaway operating conditions. Determining the thermal operating conditions of the battery pack based on the safety parameters includes: Since the temperature, air pressure, smoke concentration and voltage all meet the preset safety conditions, the battery pack is determined to be in a non-thermal runaway condition. In response to at least two of temperature, air pressure, smoke concentration and voltage satisfying the first preset thermal runaway condition, the battery pack is determined to be in a weak thermal runaway condition. In response to at least one of temperature, air pressure, smoke concentration and voltage satisfying a second preset thermal runaway condition, the battery pack is determined to be in a severe thermal runaway condition.

[0053] The non-thermal runaway condition refers to the battery pack being in normal operating condition, where all thermal behaviors are within a safe and controllable range. Under this condition, the battery pack may experience pressure fluctuations and excessive humidity. In this case, the air pressure can be regulated and moisture can be removed in a timely manner by using an exhaust fan.

[0054] Mild thermal runaway refers to the early or limited stage of thermal runaway in a battery pack. At this time, abnormal heat has been generated inside the battery, but the reaction rate and intensity are relatively low. The gas pressure increases, but does not reach the explosion threshold (i.e., opening threshold) of the explosion-proof valve body. Active prevention is required by accelerating the exhaust fan to dissipate heat and prevent the spread of heat.

[0055] A severe thermal runaway condition refers to a situation where the internal reaction of the battery is completely out of control, the temperature rises rapidly, and a large amount of flammable gas and smoke are ejected. The thermal runaway instantly reaches the opening threshold of the explosion-proof valve body. At this time, it is necessary to accelerate the exhaust fan to dissipate heat.

[0056] Furthermore, the preset safety conditions refer to: temperature below a first temperature threshold, air pressure below a first air pressure threshold, smoke concentration below a first smoke concentration threshold, and voltage below a first voltage threshold. The first preset thermal runaway condition refers to: temperature above a second temperature threshold and below a third temperature threshold, air pressure above a second air pressure threshold and below a third air pressure threshold, smoke concentration above a second smoke concentration threshold and below a third smoke concentration threshold, and voltage above a second voltage threshold and below a third voltage threshold. The second preset thermal runaway condition refers to: temperature above a third temperature threshold, air pressure above a third air pressure threshold, smoke concentration above a third smoke concentration threshold, and voltage above a third voltage threshold.

[0057] When temperature, air pressure, smoke concentration, and voltage all meet preset safety conditions, the battery pack's operating condition is determined to be a non-thermal runaway condition. When at least two of the temperature, air pressure, smoke concentration, and voltage meet the first preset thermal runaway condition, the battery pack's operating condition is determined to be a weak thermal runaway condition. When at least one of the temperature, air pressure, smoke concentration, and voltage meets the second preset thermal runaway condition, the battery pack's operating condition is determined to be a strong thermal runaway condition. The temperature threshold, smoke concentration threshold, voltage threshold, and air pressure threshold can be predetermined based on the battery pack's performance characteristics or calibration experiments, or dynamically adjusted during battery pack operation based on its thermal behavior.

[0058] S3. Control the operation of the exhaust fan according to thermal conditions and safety parameters.

[0059] According to some embodiments of this application, controlling the operation of an exhaust fan based on thermal conditions includes: controlling the exhaust fan to operate at a first speed based on air pressure and humidity in response to the battery pack being in a non-thermal runaway condition; controlling the exhaust fan to operate at a second speed based on safety parameters in response to the battery pack being in a weak thermal runaway condition; and controlling the exhaust fan to operate at maximum power in response to the battery pack being in a strong thermal runaway condition.

[0060] In non-thermal runaway conditions, the battery pack may experience pressure fluctuations and excessive humidity. In such cases, the exhaust fan is controlled to run at the highest speed to actively balance the pressure difference between the inside and outside of the battery pack, remove moisture in a timely manner, avoid condensation inside the battery pack, and avoid safety risks to the insulation of electrical components.

[0061] Under mild thermal runaway conditions, the exhaust fan is controlled to operate at a second speed based on safety parameters to accelerate air extraction and heat dissipation. This proactively extracts high-temperature, high-heat flue gas in the early stages of thermal runaway, accelerating heat dissipation, reducing the temperature and flammable gas concentration within the battery pack, inhibiting heat spread, and suppressing the escalation of the situation. The safety parameters used to control the exhaust fan are primarily those that meet the first preset thermal runaway conditions, such as temperature and air pressure, while also considering other safety parameters (such as humidity and smoke concentration) to comprehensively determine the second speed, effectively and efficiently suppressing the development of thermal runaway.

[0062] Under conditions of severe thermal runaway, the exhaust fan is controlled to operate at maximum power to pump air at maximum power, thereby accelerating the overall depressurization and heat dissipation rate. At the same time, a negative pressure environment can be formed at the outlet of the depressurization channel of the explosion-proof valve body to prevent external oxygen and other combustible gases from flowing back into the battery pack and accelerating the spread of heat.

[0063] The first speed is less than the second speed. The first and second speeds can be determined based on experimental calibration, the power level of the exhaust fan, or dynamically adjusted based on the thermal behavior of the battery pack.

[0064] In some embodiments, determining the thermal operating condition of the battery pack further includes: in response to the energy density of the battery pack being lower than an energy density threshold, determining the battery pack's operating condition as a weak thermal runaway condition when at least two of temperature, air pressure, smoke concentration, and voltage meet a first preset thermal runaway condition, and determining the battery pack's operating condition as a strong thermal runaway condition when at least one of temperature, air pressure, smoke concentration, and voltage meets a second preset thermal runaway condition; and in response to the energy density of the battery pack being higher than an energy density threshold, determining the battery pack's operating condition as a strong thermal runaway condition when at least one of temperature, air pressure, smoke concentration, and voltage meets either the first preset thermal runaway condition or the second preset thermal runaway condition.

[0065] The energy density threshold is determined based on experimental calibration or the technical standards of the battery pack. Increasing the energy density of the battery pack increases the risk of thermal runaway, leading to a more severe thermal runaway response with greater heat release, higher temperatures, faster heat propagation, and shorter system response time. In this embodiment, determining the battery pack's operating conditions based on its energy density enables tiered early warning and precise response, improving exhaust and heat dissipation efficiency, and enhancing safety and reliability.

[0066] The control method for the explosion-proof valve system of the battery pack according to this application utilizes a multi-dimensional signal coupling strategy to cross-verify and determine the true state inside the battery pack, avoiding misjudgments and omissions in thermal runaway states, thus improving the accuracy of thermal runaway prediction and providing a more comprehensive and reliable reflection of the true internal state of the battery pack. Through graded identification of thermal conditions, refined risk management of the battery pack is achieved, accurately distinguishing the severity of risks and avoiding over- or delayed responses. By controlling the exhaust fan in stages and dynamically adapting, both energy saving and protective effects are balanced. Early intervention and active protection are achieved through auxiliary exhaust cooling during the weak thermal runaway stage, reducing the hazards of thermal runaway.

[0067] The explosion-proof valve system and control method for the battery pack according to this application have the following technical advantages compared with the prior art: (1) The exhaust fan and the explosion-proof valve body are integrated into a coaxial unit. The active air extraction by the exhaust fan can improve the exhaust pressure relief efficiency, making the exhaust pressure relief and heat dissipation efficiency more than twice as high, and delaying the spread of heat. At the same time, the pressure relief is safer. The negative pressure environment formed by the exhaust fan can prevent the backflow of external oxygen and reduce the intensity of thermal runaway combustion by more than 30%. In addition, the integrated structure can be directly installed on the existing battery pack interface, with strong compatibility and adaptability, solving the problems of large modification, large space occupation, and increased installation and maintenance costs.

[0068] (2) A three-in-one design of “structural integration-functional coordination-intelligent control” has been formed. By integrating the judgment logic of the BMS system, a multi-dimensional signal coupling early warning strategy is adopted to fully identify the actual state inside the battery pack, thereby differentiating the operation of the exhaust fan, avoiding the risk of missed triggering and false triggering, and solving the problems of limited application scenarios and working conditions, high risk of missed and false alarms, and low reliability.

[0069] (3) Based on multi-dimensional signal control of exhaust fan operation, it covers ventilation and dehumidification under non-thermal runaway conditions, and quickly balances the pressure difference inside and outside the battery pack; it realizes active intervention in weak thermal runaway conditions or early stage of thermal runaway (i.e., the early stage when pressure and temperature have not reached the thermal runaway threshold), actively pumping air to dissipate heat, avoiding heat accumulation inside the battery pack, reducing the probability of later thermal spread by more than 35%, and effectively delaying thermal spread; it realizes enhanced air pumping to prevent backflow when rapid pressure relief is required under strong thermal runaway conditions; this application realizes the intelligent upgrade of the explosion-proof valve system from threshold-triggered passive response to early active identification and early prevention, the control threshold and exhaust fan power can be flexibly configured in stages by software, and can be adapted to cell systems and battery pack systems with different energy densities and thermal runaway intensities without adjusting the mechanical structure, and can cope with different scenarios and working conditions, with stronger applicability.

[0070] (4) By setting a weak area in the limiting components between the exhaust fan and the explosion-proof valve body, the safety and reliability of the system under extreme working conditions can be improved. Even if the exhaust fan itself fails, the pressure relief channel can still be kept open, thus improving the safety protection performance.

[0071] This application can simultaneously achieve automatic control under multiple scenarios and operating conditions, provide intelligent graded protection for thermal safety, and also take into account the electrical safety protection within the battery pack.

[0072] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0073] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0074] In the description of this application, "multiple" means two or more.

[0075] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0076] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0078] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An explosion-proof valve system for a battery pack, characterized in that, include: An explosion-proof valve body is disposed at the vent of the battery pack. An exhaust fan is disposed on the outside of the explosion-proof valve body and coaxially disposed with the explosion-proof valve body. The exhaust fan is connected to the explosion-proof valve body through a limiting component and a hinge component. The limiting component and the hinge component are spaced apart circumferentially. The limiting component has a weak area, which is adapted to break under the action of air pressure in the battery pack, thereby causing the exhaust fan to flip relative to the explosion-proof valve body. A controller, which is connected to the battery pack management system and the exhaust fan, is used to control the operation of the exhaust fan based on monitoring data from the battery pack management system.

2. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The outer diameter of the exhaust fan is larger than the outer diameter of the explosion-proof valve body, so as to form an annular overflow gap between the exhaust fan and the explosion-proof valve body.

3. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The battery pack management system includes a temperature monitoring module, a humidity monitoring module, an air pressure monitoring module, a smoke concentration monitoring module, and a voltage monitoring module, which are used to monitor the temperature, humidity, air pressure, and smoke concentration inside the battery pack, as well as the voltage of the battery pack.

4. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The exhaust fan is provided with a protective component on its outer side, and the flow area of ​​the protective component is greater than or equal to 80% of the cross-sectional area.

5. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The limiting component includes a connecting pin and an actuator, wherein the connecting pin connects the exhaust fan and the explosion-proof valve body and has the weak area; the actuator is connected to the connecting pin and is used to force the weak area to break.

6. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The explosion-proof valve body is equipped with a shape memory alloy valve core, which is used to adjust the flow area of ​​the pressure relief channel according to the temperature.

7. The explosion-proof valve system for a battery pack according to claim 1, characterized in that, The pressure relief channel outlet of the explosion-proof valve body is equipped with an ejector nozzle.

8. A control method for an explosion-proof valve system for a battery pack based on any one of claims 1-7, characterized in that, include: Obtain the safety parameters of the battery pack. The thermal conditions of the battery pack are determined based on the safety parameters. The exhaust fan is controlled to operate based on the thermal conditions and safety parameters.

9. The control method for an explosion-proof valve system for a battery pack according to claim 8, characterized in that, The safety parameters include the internal temperature, humidity, air pressure, smoke concentration, and voltage of the battery pack. The thermal operating conditions include non-thermal runaway, weak thermal runaway, and strong thermal runaway. Determining the thermal operating conditions of the battery pack based on the safety parameters includes: In response to the fact that the temperature, air pressure, smoke concentration and voltage all meet the preset safety conditions, the operating condition of the battery pack is determined to be the non-thermal runaway operating condition; In response to at least two of the temperature, air pressure, smoke concentration and voltage satisfying a first preset thermal runaway condition, the operating condition of the battery pack is determined to be the weak thermal runaway condition; In response to at least one of the temperature, the air pressure, the smoke concentration, and the voltage satisfying a second preset thermal runaway condition, the operating condition of the battery pack is determined to be the severe thermal runaway condition.

10. The control method for an explosion-proof valve system for a battery pack according to claim 9, characterized in that, The step of controlling the operation of the exhaust fan according to the thermal conditions includes: In response to the battery pack being in the non-thermal runaway condition, the exhaust fan is controlled to operate at a first speed based on the air pressure and the humidity. In response to the battery pack being in the weak thermal runaway condition, the exhaust fan is controlled to operate at a second speed according to the safety parameters; In response to the battery pack being in the severe thermal runaway condition, the exhaust fan is controlled to operate at maximum power.

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