An automatic trigger PACK explosion-proof valve, battery pack and control method

Abstract

The application relates to the technical field of automobile batteries, and discloses an automatic trigger PACK explosion-proof valve, a battery pack and a control method, which comprise an explosion-proof valve body, a piston assembly is slidably installed on the explosion-proof valve body, a smoke detection piece is arranged on the side surface of the explosion-proof valve body, an initiating device is arranged in the valve body, the initiating device is arranged at the bottom of the piston assembly, the initiating device and the smoke detection piece are connected with a control unit, the control unit judges whether the initiating device is triggered according to a smoke signal detected by the smoke detection piece, and the piston cover is actively opened by the initiating device; the smoke detection piece is directly integrated on the side surface of the explosion-proof valve body, the initiating device is fixed at the bottom of the piston body, and an active trigger mechanism is formed. Compared with the mode that the conventional scheme depends on the passive rise of the pressure in the battery pack to the threshold value to open the explosion-proof valve, the active trigger mechanism greatly shortens the response time from the initial stage of thermal runaway to the start of pressure relief, and effectively blocks the further spread of thermal runaway to adjacent battery cells.

Description

Technical Field

[0001] This invention relates to the field of automotive battery technology, and in particular to an automatically triggered PACK explosion-proof valve, battery pack, and control method. Background Technology

[0002] The existing thermal runaway venting protection of battery packs adopts a "warning first, pressure relief later" mode. The BMS (Battery Management System) acts as the "monitoring brain," using multi-signal cross-verification to determine whether thermal runaway is about to occur and to issue an alarm to the entire vehicle as soon as possible.

[0003] However, existing spring-loaded explosion-proof valves rely on the passive accumulation of pressure inside the battery pack to a threshold before they can open. When thermal runaway occurs, the battery cell instantly generates a large amount of gas, and the internal pressure of the battery pack rises sharply. It usually takes several seconds to tens of seconds for the pressure to rise to the threshold from the initial stage of thermal runaway. This process of "first warning, then pressure increase, and finally pressure relief" has a time difference, which leads to the explosion-proof valve not opening in time and pressure relief being delayed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an automatic triggering PACK explosion-proof valve, battery pack, and control method. By integrating a smoke detection element and an initiation device into the explosion-proof valve, an independent "sensing-triggering" closed loop is formed, enabling rapid and active pressure relief of the PACK explosion-proof valve. This effectively solves the defects of spring-type explosion-proof valves, such as delayed pressure relief and low protection efficiency.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, an automatically triggered PACK explosion-proof valve includes an explosion-proof valve body, a piston assembly slidably mounted on the explosion-proof valve body, a smoke detection element provided on the side of the explosion-proof valve body, an initiation device provided inside the valve body, the initiation device being located at the bottom of the piston assembly, and both the initiation device and the smoke detection element being connected to a control unit. The control unit determines whether to trigger the initiation device based on the smoke signal detected by the smoke detection element, and actively opens the piston cover through the initiation device.

[0006] As a further implementation, the piston assembly includes a piston body, a piston cover on the top of the piston body, a piston cover mounting groove on the top of the explosion-proof valve body, a sealing ring at the piston cover mounting groove, and the piston cover is mounted at the piston cover mounting groove and in contact with the sealing ring.

[0007] As a further implementation, the valve body is provided with an internal channel, the piston body is slidably installed in the internal channel, and the detonation device is installed at the bottom of the internal channel, located between the piston body and the bottom of the internal channel. The detonation device is a TNT device.

[0008] As a further implementation, the side of the explosion-proof valve body is provided with mounting holes for mounting and fixing the smoke detection element; the smoke detection element is a semiconductor smoke sensor.

[0009] As a further implementation, the control unit establishes communication with the vehicle's BMS.

[0010] As a further implementation, the piston body is provided with a guide groove along the axial direction on its periphery, and a guide strip is provided in the internal channel of the explosion-proof valve body, with the guide strip slidingly engaging with the guide groove.

[0011] As a further implementation, the top of the piston cover is covered with an iron sheet, which is welded to the piston cover as a whole. The piston assembly has a pressure relief channel at its center, which extends through the piston cover and piston body. The detonation device uses the pressure relief channel to push open the iron sheet.

[0012] As a further implementation, a spring is provided between the piston body and the explosion-proof valve body.

[0013] Secondly, a battery pack having an automatically triggered explosion-proof valve as described in any of the above.

[0014] Thirdly, a control method for an automatically triggered PACK explosion-proof valve, employing any of the above-described automatically triggered PACK explosion-proof valves, includes the following steps: The smoke detector detects the corresponding smoke concentration inside the battery pack. The control unit receives the smoke concentration information and determines whether the trigger threshold of the detonation device has been reached. When the trigger threshold is reached, the control unit triggers the detonation device, which actively opens the piston cover.

[0015] The beneficial effects of the present invention are as follows: This invention integrates a smoke detector directly into the side of the explosion-proof valve body and fixes an initiation device to the bottom of the piston body, forming an active triggering mechanism of smoke sensing, control judgment, instantaneous initiation, and rapid opening. The smoke detector can sense the smoke signal at close range and in real time during the initial stage of thermal runaway of the battery cell. When the smoke concentration reaches a preset threshold, the control unit immediately triggers the initiation device. The initiation device uses TNT, which releases energy instantaneously to push the piston body upward, opening the piston cover and iron plate within milliseconds, quickly creating an unobstructed exhaust channel between the battery pack and the outside. Compared with the traditional solution that relies on the pressure inside the battery pack passively rising to a threshold before opening the explosion-proof valve, this active triggering mechanism significantly shortens the response time from the initial stage of thermal runaway to the start of pressure relief. It allows high-temperature and high-pressure gas to be rapidly discharged before the thermal runaway spreads, achieving a rapid reduction in the pressure inside the battery pack. This fundamentally avoids the risk of the casing exploding due to continuous pressure accumulation and effectively blocks the further spread of thermal runaway to adjacent battery cells.

[0016] The battery pack provided by this invention is equipped with an automatically triggered PACK explosion-proof valve, enabling the battery pack to have active thermal runaway protection capabilities. Compared with the traditional battery pack's protection mode that relies on BMS early warning and passive pressure relief, the battery pack of this invention, by integrating an autonomously triggered explosion-proof valve, can complete smoke detection, judgment, and active pressure relief in the early stages of thermal runaway. The response time is shortened from several seconds to tens of seconds in traditional solutions to 100ms to 200ms, significantly improving the battery pack's thermal runaway protection capabilities and safety, and providing a more reliable guarantee for the safe operation of new energy vehicles. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the structure of the automatically triggered PACK explosion-proof valve in an embodiment of the present invention.

[0019] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0020] The components include: 1. Explosion-proof valve body; 2. Piston cover; 3. Piston body; 4. Initiation device; 5. Control unit; 6. Smoke sensor; 21. Iron sheet; 22. Pressure relief channel; 31. Spring. Detailed Implementation It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] Example 1 In a typical embodiment of the present invention, an automatically triggered PACK explosion-proof valve includes an explosion-proof valve body 1, a piston cover 2, a piston body 3, an initiation device 4, a control unit 5, a smoke sensor 6, a sheet metal 21, a pressure relief channel 22, and a spring 31.

[0022] A piston assembly is slidably mounted on the valve body 1 of the explosion-proof valve. A smoke sensor 6 is provided on the side of the valve body 1. An initiation device 4 is provided inside the valve body. The initiation device 4 is located at the bottom of the piston assembly. Both the initiation device 4 and the smoke sensor 6 are connected to the control unit 5. The control unit 5 determines whether to trigger the initiation device 4 based on the smoke signal detected by the smoke sensor 6. The piston cover 2 is opened actively by the initiation device 4.

[0023] like Figure 1As shown, the automatic triggering PACK explosion-proof valve in this embodiment mainly consists of six core components: explosion-proof valve body 1, piston assembly (including piston cover 2 and piston body 3), detonation device 4, control unit 5, and smoke sensor 6. The piston cover 2 is covered with an iron sheet 21, the piston assembly has a pressure relief channel 22 in the center, and a spring 31 is provided between the piston body 3 and the explosion-proof valve body 1.

[0024] The explosion-proof valve body 1 serves as the overall framework, providing an installation reference and gas emission passage for other components. The piston assembly (piston cover 2 and piston body 3) constitutes the pressure relief actuator, maintaining a seal under normal operating conditions and rapidly opening the exhaust passage upon triggering. The detonation device 4, acting as an active triggering source, is fixed at the bottom of the internal channel of the valve body, located between the piston body 3 and the bottom of the internal channel, replacing the passive triggering of the traditional spring and achieving millisecond-level response. The smoke sensor 6 is integrated on the side of the explosion-proof valve body 1, sensing smoke signals at close range during the initial stage of thermal runaway. The control unit 5, acting as the local brain, completes signal processing, logical judgment, trigger command output, and communication with the vehicle's BMS.

[0025] The working principle of this explosion-proof valve follows a closed-loop four-stage process: sensing, judgment, triggering, and execution. Under normal operating conditions, the smoke sensor 6 continuously monitors the smoke concentration inside the battery pack. The control unit 5 determines that the triggering condition has not been met, and the explosion-proof valve remains closed. When thermal runaway occurs in the battery cell, the smoke generated in the initial stage of thermal runaway is captured by the smoke sensor 6, and the signal is transmitted to the control unit 5. The control unit 5 determines that the smoke concentration has reached a preset threshold and immediately triggers the detonation device 4. The detonation device 4 instantly releases energy, generating high-pressure gas in the sealed space between the bottom surface of the piston body 3 and the bottom of the internal channel. This gas pushes the piston body 3 upward, opening the piston cover 2 and creating an exhaust channel between the inside of the battery pack and the outside. The high-temperature, high-pressure gas is rapidly discharged, achieving a rapid reduction in the pressure inside the battery pack and effectively preventing the spread of thermal runaway.

[0026] Compared to traditional spring-loaded explosion-proof valves that rely on the passive accumulation of pressure within the battery pack to a threshold before opening, this invention, through an active triggering mechanism, reduces the response time from several to tens of seconds in traditional solutions to 100ms to 200ms, an improvement of more than an order of magnitude. Simultaneously, the smoke sensor 6 and control unit 5 are directly integrated into the explosion-proof valve body, forming an independent "sensing-triggering" closed loop. This allows the valve to open autonomously without relying on an external BMS system, significantly improving the reliability of thermal runaway suppression.

[0027] Under normal operating conditions, the smoke detector continuously monitors the smoke concentration inside the battery pack. Control unit 5 determines that the triggering conditions have not been met, and the explosion-proof valve remains closed. When thermal runaway occurs in a battery cell, the smoke generated in the initial stage of thermal runaway is captured by the smoke detector, and the signal is transmitted to control unit 5. Control unit 5 determines that the smoke concentration has reached a preset threshold and immediately triggers detonation device 4. Detonation device 4 instantly releases energy, pushing piston body 3 upwards, opening piston cover 2, and creating an exhaust channel between the battery pack and the outside environment. High-temperature, high-pressure gas is rapidly discharged, achieving a rapid reduction in pressure inside the battery pack and effectively preventing the spread of thermal runaway. When detonation device 4 explodes, it will also break open the iron plate at the top of the pressure relief channel, simultaneously releasing pressure.

[0028] Compared to traditional spring-loaded explosion-proof valves that rely on the passive accumulation of pressure within the battery pack to a threshold before opening, this invention, through an active triggering mechanism, reduces the response time from several to tens of seconds in traditional solutions to 100ms to 200ms, an improvement of more than an order of magnitude. Simultaneously, the smoke detection component and control unit 5 are directly integrated into the explosion-proof valve body, forming an independent sensing and triggering closed loop. This allows the valve to open autonomously without relying on an external BMS system, significantly improving the reliability of thermal runaway suppression.

[0029] The explosion-proof valve body 1 is made of aluminum alloy, which has a tensile strength of over 310MPa and a yield strength of over 276MPa, while having a density of only 2.7g / cm³, balancing structural strength and lightweight requirements. Compared to traditional cast iron valve bodies, the weight is reduced by more than 40%, meeting the lightweight requirements of new energy vehicles. The overall outer diameter of the valve body is designed to be Φ80mm to Φ120mm according to the battery pack installation space, and the height is 50mm to 70mm.

[0030] The piston assembly includes a piston body 2, with a piston cap 3 on top. A piston cap mounting groove is located on the top of the explosion-proof valve body 1, and a sealing ring is installed in the piston cap mounting groove. The piston cap is mounted in the piston cap mounting groove and contacts the sealing ring. Specifically, the piston cap mounting groove is 5mm deep and its diameter matches that of the piston cap 2. An annular sealing groove, 2mm wide and 1mm deep, is formed at the bottom of the mounting groove, housing a fluororubber O-ring. The O-ring is made of FKM material, with a temperature resistance range of -20℃ to 200℃. When the piston cap 2 is assembled, the O-ring is compressed by 0.3mm to 0.5mm, achieving an initial seal between the battery pack's interior and the external environment. The sealing pressure can reach over 1MPa, meeting the airtightness requirements of the battery pack under normal operating conditions.

[0031] The valve body has an internal channel. The explosion-proof valve body 1 has a three-layer cavity structure: the top layer is the piston cover assembly groove, the middle layer is the piston body movement cavity, and the bottom layer is the exhaust channel, that is, the bottom of the internal channel is open to form the exhaust channel.

[0032] The diameter of the moving cavity of the middle piston body is Φ30mm to Φ40mm, the height is 30mm, and the inner wall roughness is controlled at Ra≤0.8μm to ensure smooth sliding of the piston body 3.

[0033] The bottom of the internal channel has a mounting position for the detonator, which uses an M20×1.5 threaded connection to fix the detonator 4. After installation, the top surface of the detonator 4 is in contact with the bottom surface of the piston body 3 or has a gap of 0.5mm to 1mm to ensure that the high-pressure gas generated by the detonator 4 can effectively push the piston body 3 upward. The detonator is a TNT device.

[0034] The explosion-proof valve body 1 has mounting holes on its side for mounting and fixing the smoke sensor 6. Specifically, two M5 threaded mounting holes are provided on the side of the valve body for fixing the smoke sensor 6. The mounting holes are located close to the piston body's movement cavity, so that the detection end of the smoke sensor 6 faces directly into the battery pack, enabling it to detect smoke generated by thermal runaway immediately. The mounting holes use a threaded connection, and a 1mm thick polytetrafluoroethylene (PTFE) gasket is placed between the smoke sensor 6 and the valve body to prevent gas leakage from the mounting gap.

[0035] The explosion-proof valve body 1 has guide strips corresponding to its internal channel. Specifically, two guide strips are arranged axially on the inner wall of the cavity. The guide strips are 2mm wide and 1mm high. They cooperate with the guide groove on the outside of the piston body 3 to form radial and rotational constraints on the piston body 3, ensuring that the piston body 3 can only move linearly along the axial direction and does not undergo radial offset or rotation.

[0036] The bottom exhaust channel adopts a conical expansion design with an inlet diameter of Φ40mm, an outlet diameter of Φ60mm, and a channel length of 20mm. The conical design gradually increases the gas flow cross-sectional area, reducing flow resistance and improving exhaust efficiency. The inner wall of the channel is polished, with a surface roughness Ra≤0.4μm, further reducing gas flow friction resistance.

[0037] The piston cover mounting groove is 5mm deep and its diameter matches that of piston cover 2. An annular sealing groove, 2mm wide and 1mm deep, is formed at the bottom of the mounting groove, housing a fluororubber O-ring. The O-ring is made of FKM material, with a temperature resistance range of -20℃ to 200℃. After piston cover 2 is assembled, the O-ring is compressed by 0.3mm to 0.5mm, achieving an initial seal between the battery pack's interior and the external environment. The sealing pressure can reach over 1MPa, meeting the airtightness requirements of the battery pack under normal operating conditions.

[0038] The explosion-proof valve body 1 has mounting holes on its side for installing and fixing a smoke detection element; the smoke detection element is a semiconductor smoke sensor. Specifically, two M5 threaded mounting holes are provided on the side of the valve body for fixing the smoke detection element. The mounting holes are located close to the piston body's movement cavity, allowing the detection end of the smoke detection element to directly face the inside of the battery pack, enabling immediate detection of smoke generated by thermal runaway. The mounting holes use a threaded connection, and a 1mm thick PTFE sealing gasket is placed between the smoke detection element and the valve body to prevent gas leakage from the installation gap.

[0039] The piston assembly is slidably installed in the internal channel of the explosion-proof valve body 1 to realize the pressure relief function. The piston assembly consists of two main parts: piston body 3 and piston cover 2. The piston cover 2 and piston body 3 are mechanically connected to form an integral whole. A pressure relief channel 22 is provided in the center. A spring 31 is provided between piston body 3 and explosion-proof valve body 1 to provide preload force.

[0040] The detonation device 4 is a TNT device, installed at the bottom of the internal channel, between the piston body 3 and the bottom of the internal channel. As the active triggering source of this invention, the detonation device 4 replaces the passive triggering of the traditional spring, achieving a millisecond-level response of receiving a signal, instantly releasing energy, and driving the piston body.

[0041] The detonation device 4 consists of a miniature TNT charge, an igniter, a safety mechanism, and electrodes. The miniature TNT charge uses military-grade TNT explosive with a purity greater than 99.5%, and the amount of explosive is controlled between 0.5g and 1.0g.

[0042] The charge design takes into account two factors: firstly, it needs to provide sufficient energy to drive the piston 3 to move rapidly, overcoming its own weight, frictional resistance, and the pre-tightening force of the sealing ring, and also needs to break open the iron plate through the pressure relief channel 22; secondly, it needs to avoid excessive energy that could damage the valve body structure or cause excessive impact. A charge of 0.5g to 1.0g ensures that the released energy drives the piston 3 to complete a stroke of 30mm to 40mm within 5ms to 10ms, with a movement speed of 6m / s to 10m / s, while the impact force generated by the explosion is controlled within a reasonable range and will not cause destructive damage to the valve body.

[0043] The igniter uses a bridge wire igniter with a bridge wire resistance of 1.0Ω to 1.5Ω. The bridge wire is made of nickel-chromium alloy, with a diameter of 0.05mm and a length of 2mm. When the control unit 5 outputs a drive current, the current passes through the bridge wire, which rapidly heats up due to resistance heating. The ignition current is designed to be 1A to 2A. Under this current, the bridge wire temperature rises to above 800℃ within 1ms, igniting the TNT charge in contact with it. The ignition time is less than 1ms, ensuring rapid trigger response.

[0044] The safety mechanism employs a mechanical safety pin design. The safety pin is made of stainless steel, pin-shaped, 2mm in diameter and 10mm in length. Before the detonator 4 is installed, the safety pin is inserted between the igniter and the TNT charge, physically blocking their contact. Even if the igniter is powered on and the bridge wire heats up, the TNT charge cannot be ignited, thus preventing accidental triggering during transportation, storage, or assembly. After assembly, the safety pin is removed using a special tool, and the detonator 4 enters the working state. The safety pin is designed for single use and cannot be reset after removal, ensuring that the explosion-proof valve is in a ready-to-trigger state after assembly.

[0045] The electrode uses gold-plated copper needles, 1mm in diameter and 15mm in length, with a gold plating thickness of 3μm to 5μm. The gold plating enhances the electrode surface conductivity and oxidation resistance, ensuring reliable electrical contact during long-term use. One end of the electrode is soldered to the igniter bridge wire, and the other end is connected to the trigger drive circuit of control unit 5 via a pin-type electrical connector. The electrical connector features a vibration-resistant design with a contact resistance of less than 10mΩ, ensuring stable transmission of the drive current.

[0046] The detonation device 4 is fixed at the bottom of the internal channel of the valve body, located between the piston body 3 and the bottom of the internal channel. After installation, the top surface of the detonation device 4 is in contact with the bottom surface of the piston body 3 or has a gap of 0.5mm to 1mm.

[0047] The bottom of the internal passage of the valve body is provided with an opening, which allows gas to enter the internal passage through the opening and then push open the iron plate through the pressure relief passage to achieve pressure relief.

[0048] When the control unit 5 determines that the smoke concentration has reached the threshold, it triggers the MOSFET in the drive circuit to conduct. The 12V power supply voltage is applied to both ends of the igniter bridge wire through the MOSFET and electrodes, and a drive current of 1A to 2A flows through the bridge wire. The bridge wire heats up to over 800°C within 1ms, igniting the TNT charge. After ignition, the TNT charge completes combustion within 1ms to 5ms. During combustion, TNT molecules decompose and release a large amount of gaseous products, including nitrogen, carbon monoxide, carbon dioxide, and water vapor, with the gas temperature reaching over 2000°C. The gas expands rapidly in the confined space, and the pressure instantly rises to several megapascals. The high-pressure gas generates an upward thrust on the bottom of the piston body 3, with a peak thrust exceeding 5000N. Driven by high-pressure gas, piston 3 overcomes its own weight, frictional resistance and sealing ring preload. At the same time, the elastic force of spring 31 and the thrust of high-pressure gas are superimposed, and piston 3 begins to accelerate upward. It completes an upward stroke of 30mm to 40mm within 5ms to 10ms, with an average speed of 6m / s to 10m / s.

[0049] The smoke sensor 6 employs a semiconductor smoke sensor, specifically the SGX-MPX4115A or a similar high-precision sensor. This sensor exhibits a response time of less than or equal to 100ms for characteristic smoke gases in the early stages of thermal runaway (CO concentration ≥ 50ppm, H2 concentration ≥ 100ppm), a detection accuracy error of less than or equal to 5%, and an operating temperature range of -40℃ to 125℃, making it fully suitable for the harsh environment within the battery pack. Compared to traditional optical sensors, semiconductor sensors are smaller (3mm × 3mm × 2mm) and easier to integrate into explosion-proof valves.

[0050] The smoke sensor chip is coated with tin oxide as a sensitive material. Tin oxide is an N-type semiconductor material. In the air, it adsorbs oxygen molecules on its surface. These oxygen molecules capture electrons to form oxygen ions, resulting in a decrease in the electron concentration and conductivity of the tin oxide surface. When reducing gases such as CO and H2 are present in the environment, the reducing gases react with the adsorbed oxygen ions in a redox reaction. The oxygen ions release electrons and return to the tin oxide, increasing the surface electron concentration and conductivity, and consequently increasing the sensor's output voltage signal.

[0051] The sensor chip measures 3mm × 3mm × 2mm and operates within a temperature range of -40℃ to 125℃. The sensor responds to smoke with CO concentrations greater than 50ppm and H2 concentrations greater than 100ppm in less than 100ms, with a detection accuracy error of less than 5%, exhibiting higher sensitivity than traditional optical sensors.

[0052] The smoke sensor 6 consists of a smoke sensor chip, a signal amplification circuit, a filter circuit, and a metal casing. The signal amplification circuit uses an operational amplifier to amplify the weak signal output from the sensor chip to a standard voltage range of 0V to 5V, with a magnification factor of 10. The amplified signal then enters the filter circuit, which uses an RC low-pass filter with a cutoff frequency of 1kHz to remove high-frequency noise and improve the signal-to-noise ratio.

[0053] The smoke sensor 6 is fixed to the mounting hole on the side of the explosion-proof valve body 1 via an M5 threaded connection. A 1mm thick PTFE gasket with a compression of 0.2mm to 0.3mm is placed between the housing and the valve body to prevent gas leakage from the mounting gap. The smoke sensor 6 is positioned so that its detection end faces directly into the battery pack, at a distance of 50mm to 200mm from the battery cell, enabling it to detect smoke signals immediately in the early stages of thermal runaway. The signal output of the smoke sensor 6 is connected to the signal input of the control unit 5 via two AWG26 high-temperature resistant wires. The wires are 200℃ resistant and wrapped with a fiberglass sheath to improve their anti-aging properties and mechanical strength. The wires are relatively short, typically less than 100mm, to reduce signal transmission delay and electromagnetic interference, ensuring accurate and timely transmission of smoke signals to the control unit 5.

[0054] The control unit 5, serving as the local brain of this invention, undertakes four main functions: signal processing, logical judgment, trigger instruction output, and status feedback. The control unit 5 uses a microcontroller as its core processor, possessing powerful computing capabilities, low power consumption, and high anti-interference performance.

[0055] The microcontroller used is the STM32L4 series, model STM32L431RCT6, based on the ARM Cortex-M4 core with a main frequency of 80MHz. This chip integrates a 12-bit ADC module with a sampling rate greater than 1MHz, enabling high-precision, high-speed acquisition of the analog signal output from the smoke sensor 6. The chip operates at a voltage of 3.0V to 3.6V and has a sleep current of less than 1μA, meeting low power consumption requirements. The chip features ESD protection of ±8kV contact discharge, excellent anti-interference performance, and is suitable for the strong electromagnetic interference environment within the battery pack.

[0056] The control unit 5 circuit is divided into four functional modules: signal acquisition circuit, logic control circuit, trigger drive circuit, and communication circuit. The signal acquisition circuit processes the analog signal output from the smoke sensor 6. The analog signal voltage range is 0V to 5V. It first passes through an RC low-pass filter circuit to filter out high-frequency noise, with a cutoff frequency of 1kHz. The filtered signal then enters the microcontroller's ADC module. The ADC has a 12-bit resolution and a sampling rate set to 100kHz, converting the analog signal into a digital signal. The digital signal range is 0 to 4095, corresponding to an analog signal of 0V to 5V.

[0057] The threshold setting is based on the correspondence between smoke concentration and sensor output voltage, typically set to the digital signal values ​​corresponding to a CO concentration of 50 ppm and an H2 concentration of 100 ppm. The microcontroller compares the digital signals acquired by the ADC in real time. If the digital signal is less than the threshold, it is determined that the smoke concentration has not reached the trigger condition, and monitoring continues. If the digital signal reaches or exceeds the threshold, it is determined that the smoke concentration has reached the trigger condition, and the logic control circuit immediately outputs a trigger command. To avoid false triggering, the logic control circuit has a continuous judgment mechanism, that is, the trigger command is only output after three consecutive sampling digital signals reach or exceed the threshold.

[0058] After receiving the trigger command from the logic control circuit, the trigger drive circuit provides drive current to the igniter of the detonation device 4. The trigger drive circuit uses a MOSFET as the switching element, model IRF740, with a maximum drain-source voltage of 400V, a maximum drain-source current of 10A, and an on-resistance of less than 0.5Ω. The gate of the MOSFET is connected to the GPIO pin of the microcontroller. When the microcontroller outputs a high-level trigger signal, the MOSFET turns on, and the 12V power supply voltage is applied to the two ends of the bridge wire of the igniter of the detonation device 4 through the MOSFET and electrodes. A drive current of 1A to 2A flows through the bridge wire, triggering detonation.

[0059] Control unit 5 establishes communication with the vehicle's BMS. The communication circuit uses the CAN bus protocol to communicate with the vehicle's BMS, conforming to the ISO 11898-2 standard. The communication circuit uses a CAN transceiver, model TJA1050, supporting a maximum communication rate of 1Mbps. In this application, it is set to 500kbps to ensure real-time signal transmission. The communication circuit performs three main functions: periodically uploading smoke concentration data, trigger status feedback, and receiving external forced trigger commands.

[0060] Control unit 5 sends the current smoke concentration data to the vehicle BMS via the CAN bus every 100ms. The data format is a standard CAN frame, containing the smoke concentration value and a timestamp. After receiving the data, the BMS can monitor the smoke status of the battery pack in real time, serving as an auxiliary basis for thermal runaway warning.

[0061] When control unit 5 triggers detonation device 4, it immediately sends a triggered status signal to BMS via the CAN bus, with a signal transmission delay of less than 50ms. Upon receiving the trigger signal, BMS can promptly take subsequent safety measures, such as disconnecting the high-voltage power supply via the high-voltage relay, activating the fire extinguishing device, and issuing an alarm to the driver. In special circumstances, if BMS determines through other sensors that the risk of thermal runaway is extremely high, it can send a forced trigger command to control unit 5 via the CAN bus. Upon receiving the forced trigger command, control unit 5 immediately triggers detonation device 4, enabling remote opening of the explosion-proof valve. This function provides dual trigger protection for the explosion-proof valve, allowing it to be triggered autonomously or by receiving external commands.

[0062] The low-voltage wiring harness is a high-temperature resistant harness with a rated voltage of 12V and a temperature resistance of 125℃. It connects the smoke sensor 6 to the control unit 5 and the trigger drive circuit. The low-voltage wiring harness adopts a shielded design with an outer aluminum foil shielding layer, achieving a shielding efficiency of over 90% and reducing electromagnetic interference. The low-voltage wiring harness connects to the smoke sensor 6 and the detonation device 4 via a waterproof connector. The connector has an IP67 protection rating, ensuring reliable connection even in humid environments with the battery pack.

[0063] After the explosion-proof valve is installed in the battery pack, the control unit 5 is in operation, and the smoke sensor 6 continuously monitors the smoke concentration inside the battery pack. Under normal operating conditions, the smoke concentration inside the battery pack is extremely low, and the output signal of the smoke sensor 6 is less than the threshold. The control unit 5 determines that the triggering condition has not been met, the explosion-proof valve remains closed, the piston cover 2 is sealed to the valve body, and the inside of the battery pack is isolated from the outside.

[0064] When a battery cell experiences thermal runaway due to internal short circuits, external impacts, overcharging, or over-discharging, the internal temperature of the cell rises sharply, causing the electrolyte and positive and negative electrode materials to decompose and generate a large amount of high-temperature, high-pressure gas and smoke. The smoke mainly consists of CO, H2, carbon particles, and organic vapors. After being ejected from the safety valve or a ruptured part of the thermally runaway battery cell, the smoke rapidly diffuses within the battery pack. Reaching the vicinity of the smoke sensor 6 on the explosion-proof valve, the smoke enters the casing through the vents on the side of the metal casing and comes into contact with the tin oxide sensitive material on the surface of the smoke sensor chip. The reducing gases such as CO and H2 in the smoke react with adsorbed oxygen ions in a redox reaction, increasing the electron concentration and conductivity on the tin oxide surface, thus increasing the sensor's output voltage signal. This process has a response time of less than 100 ms.

[0065] The analog signal output by the sensor is amplified 10 times by a signal amplification circuit, then filtered to remove noise before being transmitted to the signal acquisition circuit of control unit 5. The ADC module of the signal acquisition circuit converts the analog signal into a 12-bit digital signal at a sampling rate of 100kHz. This process takes approximately 10μs. The logic control circuit performs real-time judgment on the digital signal. When the digital signal reaches or exceeds a preset threshold, the logic control circuit determines that the smoke concentration has reached the trigger condition and immediately outputs a trigger command. From the moment the smoke contacts the sensor to the output of the trigger command, the entire signal processing process takes approximately 100ms to 150ms.

[0066] After receiving the trigger command, the gate voltage of the MOSFET increases, and the MOSFET turns on. A 12V power supply is applied through the MOSFET and electrodes to the igniter bridge wire of the detonator 4, driving a current of 1A to 2A through the bridge wire. The bridge wire rapidly heats up under resistance heating, reaching over 800°C within 1ms, igniting the TNT charge in contact with it. After ignition, the TNT charge completes combustion within 1ms to 5ms, releasing a large amount of high-temperature, high-pressure gas. This gas rapidly expands in the sealed space between the bottom surface of the piston body 3 and the bottom of the internal channel, instantly increasing the pressure to several megapascals, generating an upward thrust on the bottom of the piston body 3, with a peak thrust exceeding 5000N.

[0067] Driven by high-pressure gas, piston 3 overcomes its own weight, frictional resistance, and spring force, accelerating upwards while the spring is compressed. The outer guide groove of piston 3 engages with the inner guide strip of the valve body to ensure linear axial movement without radial offset or rotation. Within 5ms to 10ms, piston 3 completes an upward stroke of 30mm to 40mm, reaching a speed of 6m / s to 10m / s. The upward movement of piston 3 drives piston cover 2 upwards, which overcomes the O-ring preload and its own weight, lifting along the edge of the mounting groove. Due to the chamfered edge design of the piston cover, it smoothly detaches from the mounting groove. Simultaneously, the gas generated by the explosion passes through the pressure relief channel, moves upwards, and forces open the metal plate, achieving pressure relief. Subsequent pressure relief gas can be discharged through the opening at the bottom of the internal channel and the pressure relief channel.

[0068] After the piston cover 2 is opened, the venting channel between the battery pack and the outside is opened. Simultaneously, the pressure relief channel 22 at the center of the piston assembly continues to provide venting. As gas continues to escape, the internal pressure of the battery pack rapidly decreases. Assuming the internal pressure of the battery pack rises to 0.5 MPa to 1.0 MPa in the initial stage of thermal runaway, after the venting channel opens, the internal pressure of the battery pack drops to below 0.1 MPa within 1 to 3 seconds. This pressure reduction allows the high-temperature gas generated by thermal runaway to be rapidly expelled, the temperature inside the battery pack decreases, and the heat transfer from thermal runaway to adjacent cells is blocked, effectively preventing the spread of thermal runaway.

[0069] After triggering the detonation device 4, control unit 5 immediately sends a triggered status signal to the vehicle's BMS via the CAN bus, with a signal transmission delay of less than 50ms. Upon receiving the signal, the BMS disconnects the high-voltage power supply via the high-voltage relay, activates the fire extinguishing device to spray extinguishing agent onto the battery pack, and prompts the driver to stop the vehicle immediately and leave via the instrument panel and voice prompts, minimizing the harm of thermal runaway accidents. From the time the smoke sensor 6 detects the smoke signal reaching the threshold to the piston cover 2 being opened and pressure relief beginning, the entire response time is approximately 100ms to 200ms. Compared to the traditional spring-loaded explosion-proof valve, which relies on the passive accumulation of pressure within the battery pack to reach the threshold before opening, the response time of traditional solutions is typically several seconds to tens of seconds. This invention improves the response speed by more than an order of magnitude, significantly shortening the time window from the initial stage of thermal runaway to the start of pressure relief, effectively preventing the spread of thermal runaway, and significantly improving the safety protection capability of the battery pack.

[0070] Example 2 In another embodiment of the present invention, a battery pack is provided, on which an automatically triggered PACK explosion-proof valve as described above is installed.

[0071] The battery pack consists of a battery pack housing, cell arrays, a BMS system, a thermal management system, a high-voltage power distribution system, and an automatically triggered explosion-proof valve. The battery pack housing is made of aluminum alloy and is rectangular in shape, providing mechanical support and protection for the cell arrays and various systems. Multiple mounting brackets are located on the top of the housing for securing components such as the explosion-proof valve, BMS system, and high-voltage power distribution system. The sides of the housing feature high-voltage interfaces, communication interfaces, and coolant interfaces.

[0072] An automatically triggered explosion-proof valve is installed at a pre-set position on the top of the battery pack housing, serving as the last physical barrier against thermal runaway. The installation location of the explosion-proof valve takes into account factors such as monitoring coverage, avoidance of critical components, and ease of exhaust channel layout. The installation position should allow the smoke sensor 6 to cover the main areas inside the battery pack, especially near the cell modules with a high risk of thermal runaway. The smoke sensor 6 is positioned 50mm to 200mm away from the cells, enabling it to detect smoke signals at the earliest stage of thermal runaway. The installation position should avoid critical components such as the BMS main control unit, high-voltage relays, and high-voltage connectors to prevent damage to these components from the high-temperature gas emitted when the explosion-proof valve opens. It should also avoid coolant lines and high-voltage wiring harnesses to prevent gas impacts that could lead to leaks or short circuits. The explosion-proof valve is bolted to a mounting base on the top of the battery pack housing. The mounting base is made of aluminum alloy and welded integrally with the housing, providing sufficient mechanical strength.

[0073] Example 3 In another embodiment of the present invention, a control method for automatically triggering a PACK explosion-proof valve is provided. The method employs the automatically triggering PACK explosion-proof valve as described above and includes the following steps: the smoke sensor 6 detects the corresponding smoke concentration inside the battery pack; the control unit 5 receives the smoke concentration information and determines whether the trigger threshold of the detonation device 4 has been reached; when the trigger threshold is reached, the control unit 5 triggers the detonation device 4, which actively opens the piston cover 2; simultaneously, the gas generated after detonation opens the iron plate through the pressure relief channel, thereby connecting the pressure relief channel with the outside environment for convenient pressure relief.

[0074] The control method comprises four core steps: smoke concentration detection, smoke concentration judgment, triggering the detonation device, and opening the piston cover and sheet metal. This achieves a complete control process from initial smoke signal detection in the early stages of thermal runaway to rapid pressure relief. The core difference between this control method and traditional solutions lies in the following: Traditional solutions rely on a BMS (Battery Management System) to detect thermal runaway signals through separate smoke and pressure sensors. After judgment, the BMS sends an opening command to the explosion-proof valve via a signal line. The explosion-proof valve passively opens when the pressure inside the battery pack rises to a threshold. This process suffers from drawbacks such as multi-stage signal transmission delays, BMS failure risks, and long pressure accumulation times. This control method integrates the smoke sensor 6 and control unit 5 into the explosion-proof valve body, forming an independent sensing-judgment-trigger closed loop. It can autonomously complete the valve opening action without relying on an external BMS, and uses a TNT detonation device for active triggering, eliminating the need to wait for pressure accumulation. The response speed is reduced from several to tens of seconds in traditional solutions to 100ms to 200ms.

[0075] An explosion-proof valve is installed after the battery pack, and smoke sensor 6 continuously monitors the smoke concentration inside the battery pack. When the smoke sensor chip of smoke sensor 6 is operational, the tin oxide sensitive material on the chip surface adsorbs oxygen molecules from the air. These oxygen molecules capture electrons to form oxygen ions, reducing the electron concentration on the tin oxide surface and decreasing its conductivity. The sensor then outputs a reference voltage signal. Under normal operating conditions, the smoke concentration inside the battery pack is extremely low, with CO concentration less than 10 ppm and H2 concentration less than 20 ppm. The sensor output voltage signal is approximately 0.5V to 1.0V.

[0076] The signal acquisition circuit of control unit 5 acquires and converts the signal. The ADC module converts the analog signal into a digital signal. The digital signal value is about 400 to 800, which is far below the preset threshold. The logic control circuit determines that the triggering condition has not been met, and the explosion-proof valve remains closed.

[0077] When a battery cell experiences thermal runaway, the internal temperature rises rapidly, causing the electrolyte and positive and negative electrode materials to decompose and generate large amounts of high-temperature, high-pressure gases and fumes. The electrolyte's main components are carbonate solvents, such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate, which decompose to produce gases like CO, CO2, CH4, and C2H4. The negative electrode graphite material reacts with the electrolyte at high temperatures to produce H2. The positive electrode material, such as ternary cathode materials, decomposes at high temperatures to release O2, which reacts with the electrolyte to produce CO. The fumes, ejected from the safety valve or ruptured casing of the thermally runaway cell, rapidly diffuse within the battery pack. The diffusion rate is affected by factors such as the internal structure of the battery pack and airflow channels; typically, within seconds, the fumes concentration rises to over 50 ppm for CO and over 100 ppm for H2.

[0078] Smoke diffuses to the vicinity of the smoke sensor 6 on the explosion-proof valve, entering the interior of the metal housing through the vent on the side of the sensor's casing and coming into contact with the tin oxide sensitive material on the surface of the smoke sensor chip. Reducing gases such as CO and H2 in the smoke undergo a redox reaction with oxygen ions adsorbed on the tin oxide surface. Electrons released in the reaction return to the tin oxide, increasing the surface electron concentration and conductivity, thus increasing the sensor's output voltage signal. When the CO concentration reaches 50 ppm and the H2 concentration reaches 100 ppm, the sensor's output voltage signal rises to 3.0V to 4.0V. This response process takes less than 100 ms.

[0079] After receiving the analog signal output from the smoke sensor 6, the signal acquisition circuit of control unit 5 processes the signal. The analog signal first passes through an RC low-pass filter circuit to remove high-frequency noise, with a cutoff frequency of 1kHz. The filtered signal then enters the microcontroller's ADC module. The ADC module converts the analog signal into a 12-bit digital signal with a resolution of 4096 levels, corresponding to an analog signal value of 0V to 5V. When the smoke concentration increases, causing the analog signal to rise to 3.0V to 4.0V, the digital signal value becomes 2400 to 3200. The ADC sampling rate is set to 100kHz, and the sampling period is 10μs to ensure a fast response to the smoke signal.

[0080] The logic control circuit compares the digital signal acquired by the ADC with a preset threshold in real time. The threshold is set based on the correspondence between smoke concentration and sensor output voltage, typically set to the digital signal value corresponding to a CO concentration of 50 ppm and an H2 concentration of 100 ppm, approximately 2500. The logic control circuit checks the digital signal every 1 ms to ensure timely detection of smoke concentration reaching the trigger condition. If the digital signal is less than the threshold 2500, the logic control circuit determines that the smoke concentration has not reached the trigger condition, continues monitoring, and does not output a trigger command. The control unit 5 remains in standby mode, while the smoke sensor 6 continuously monitors the smoke concentration in the battery pack, forming a continuous monitoring cycle. If the digital signal reaches or exceeds the threshold 2500, the logic control circuit determines that the smoke concentration has reached the trigger condition and immediately outputs a trigger command. To avoid false triggering, the logic control circuit can be set with a continuous judgment mechanism, i.e., the trigger command is only output after the digital signal reaches or exceeds the threshold for three consecutive samples (taking 3 ms). The entire signal processing process, from smoke contact with the sensor to the output of the trigger command, takes approximately 100 ms to 150 ms.

[0081] After the logic control circuit outputs the trigger command, the trigger command signal is output from the microcontroller's GPIO pin, with a high level of 3.3V. This signal is applied to the gate of the MOSFET in the trigger drive circuit. The MOSFET is an IRF740, an N-channel enhancement-mode MOSFET with a gate threshold voltage of 2V to 4V. When the gate voltage reaches 3.3V, the MOSFET turns on, forming a low-resistance path between the drain and source, with an on-resistance of less than 0.5Ω. The MOSFET source is grounded, and the drain is connected to the positive terminal of the 12V power supply. A current-limiting resistor with a resistance of 8Ω is connected in series between the drain and the positive terminal of the ignition bridge wire of the detonator, limiting the drive current to 1.5A.

[0082] After the MOSFET is turned on, the 12V power supply voltage is applied to the ignition bridge wire of the detonator 4 through the MOSFET, current-limiting resistor, and electrodes. The bridge wire resistance is 1.2Ω, and the driving current is 1.5A. The bridge wire heats up rapidly under the resistance heating effect, with a temperature rise rate of approximately 800℃ / ms. Within 1ms, the temperature rises from room temperature (25℃) to 825℃, reaching the ignition temperature of the TNT charge. The high temperature of the bridge wire ignites the TNT charge in contact with it. TNT is a solid explosive, and after ignition, it undergoes a rapid combustion reaction, releasing a large amount of heat, approximately 4000kJ / kg. 0.5g to 1.0g of TNT charge releases 2kJ to 4kJ of heat. The TNT combustion process is completed within 1ms to 5ms. The gaseous products of combustion include nitrogen, water vapor, carbon monoxide, and solid carbon particles, with gas temperatures exceeding 2000℃. The gas expands rapidly in the space between the bottom surface of the piston body 3 and the bottom of the internal channel, and the pressure instantly rises to several megapascals. The high-pressure gas generates an upward thrust on the bottom of the piston body 3, with a peak thrust exceeding 5000N.

[0083] Piston 3, propelled by the high-pressure gas generated by detonation device 4, withstands an upward thrust of over 5000N. Piston 3 is made of 45# steel, with a density of 7.85g / cm³, a volume of approximately 40cm³, a mass of approximately 314g, and a self-weight of approximately 3.1N.

[0084] The piston 3 accelerates upward from rest, while the spring 31 is compressed by the valve body and piston body under the thrust of high-pressure gas. The spring 31 is pre-compressed by 3mm to 5mm. When the piston 3 moves upward, the spring 31 is further compressed, and the elastic force increases.

[0085] During the movement of piston body 3, the outer guide groove and the inner guide strip of valve body slide together. The guide strip forms radial and rotational constraints on the guide groove, ensuring that piston body 3 can only move in a straight line along the axial direction and does not undergo radial offset or rotation. The upward movement of piston body 3 drives piston cover 2 to move upward. After being subjected to force, piston cover 2 overcomes the O-ring preload force of 30N and its own weight of about 1N, and moves away from the edge of the assembly groove.

[0086] After the piston cover 2 is opened, the venting channel between the battery pack and the outside is opened. At the same time, the iron plate at the top of the pressure relief channel 22 in the center of the piston assembly is blasted open to continue providing a venting channel. The pressure relief channel 22 has a diameter of Φ2mm to Φ3mm, and the rapid discharge of gas causes the internal pressure of the battery pack to drop rapidly.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatically triggered PACK explosion-proof valve, characterized in that, The device includes an explosion-proof valve body, a piston assembly that is slidably mounted on the explosion-proof valve body, a smoke detection element on the side of the explosion-proof valve body, and an initiation device inside the valve body. The initiation device is located at the bottom of the piston assembly. Both the initiation device and the smoke detection element are connected to a control unit. The control unit determines whether to trigger the initiation device based on the smoke signal detected by the smoke detection element, and the piston cover is opened actively by the initiation device.

2. The automatic triggering PACK explosion-proof valve according to claim 1, characterized in that, The piston assembly includes a piston body, a piston cap on the top of the piston body, a piston cap assembly groove on the top of the explosion-proof valve body, a sealing ring at the piston cap assembly groove, and the piston cap is assembled at the piston cap assembly groove and contacts the sealing ring.

3. The automatic triggering PACK explosion-proof valve according to claim 1, characterized in that, The valve body is provided with an internal channel, the piston body is slidably installed in the internal channel, and the detonation device is installed at the bottom of the internal channel, located between the piston body and the bottom of the internal channel. The detonation device is a TNT device.

4. The automatic triggering PACK explosion-proof valve according to claim 1, characterized in that, The explosion-proof valve body has mounting holes on its side for mounting and fixing the smoke detection element; the smoke detection element is a semiconductor smoke sensor.

5. An automatically triggered PACK explosion-proof valve according to claim 4, characterized in that, The control unit establishes communication with the vehicle's BMS.

6. The automatic triggering PACK explosion-proof valve according to claim 2, characterized in that, The piston body is provided with a guide groove along the axial direction on its periphery, and the explosion-proof valve body is provided with a guide bar in the internal channel, with the guide bar slidingly engaging with the guide groove.

7. An automatically triggered PACK explosion-proof valve according to claim 2, characterized in that, The top of the piston cover is covered with an iron sheet, which is welded to the piston cover as a whole; The piston assembly has a pressure relief channel at its center, which extends through the piston cover and piston body. The detonation device uses the pressure relief channel to push open the iron sheet.

8. An automatically triggered PACK explosion-proof valve according to claim 7, characterized in that, A spring is provided between the piston body and the explosion-proof valve body.

9. A battery pack, characterized in that, The battery pack is equipped with an automatically triggered PACK explosion-proof valve as described in any one of claims 1-8.

10. A control method for automatically triggering a PACK explosion-proof valve, characterized in that, The automatic triggering PACK explosion-proof valve as described in any one of claims 1-8 includes the following steps: The smoke detector detects the corresponding smoke concentration inside the battery pack. The control unit receives the smoke concentration information and determines whether the trigger threshold of the detonation device has been reached. When the trigger threshold is reached, the control unit triggers the detonation device, which actively opens the piston cover.

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