A multi-stage triggering structure design method of a battery pack explosion relief valve

Abstract

The application discloses a multi-stage triggering structure design method of a battery pack explosion pressure relief valve, and particularly relates to the technical field of battery pack thermal runaway safety protection, and is used for solving the problem of response lag or failure of normal opening of other pressure relief valves caused by dynamic back pressure in a shared pressure relief channel; a pressure monitoring point is arranged at each branch inlet of the shared pressure relief channel to monitor a dynamic pressure value in real time, a corresponding pressure release cavity is started when the pressure value reaches a threshold value to form a temporary bypass, a flow guide structure is used to perform cyclone separation on airflow to analyze the density distribution of gas-solid two-phase flow, vortex core oscillation frequency and amplitude are monitored, the discharge stage is determined according to the density distribution and frequency drift and amplitude growth characteristics, and the outlet area of the pressure release cavity is adjusted, finally, the back pressure compensation mechanism of other non-triggered pressure relief valves is controlled to enter a standby triggering state, and the cooperative protection and graded pressure relief functions of the multi-stage triggering structure are realized.

Description

Technical Field

[0001] This invention relates to the field of battery pack thermal runaway safety protection technology, and more specifically, to a multi-stage triggering structure design method for a battery pack explosion relief valve. Background Technology

[0002] The increasing energy density of power batteries makes thermal runaway safety protection in battery pack structural design increasingly important. As a key safety component for suppressing battery pack explosions, the design concept of pressure relief valves has evolved from simple instantaneous pressure relief to multi-stage triggering and graded pressure relief. This aims to achieve coordinated protection of early warning and main body discharge through orderly actions at different thresholds. In large multi-module battery packs, due to space layout and system integration requirements, a common design solution is to converge the pressure relief paths of multiple battery modules through a shared pressure relief channel, ultimately discharging through a unified pressure relief port. This structure has become a prevalent technical practice in this field.

[0003] However, the existing design using a shared pressure relief channel has a systemic flaw: when a module experiences thermal runaway and triggers its corresponding pressure relief valve first, the ejected high-speed airflow creates a significant dynamic back pressure within the shared channel. This back pressure acts on other pressure relief valves that have not yet been triggered, effectively increasing the external environmental pressure they need to overcome to activate. This results in delayed response or even failure of the pressure relief valves in adjacent modules to open normally at preset thresholds. The essence of this problem is that after multiple pressure relief units are coupled through a shared fluid channel, their expected independent action logic is disrupted, leading to mutual inhibition between safety functions and severely weakening the redundant safety performance that a multi-stage triggering structure should provide. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a multi-stage triggering structure design method for a battery pack explosion relief valve to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A multi-stage triggering structure design method for a battery pack explosion relief valve includes the following steps:

[0007] S1. Set up pressure monitoring points at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure value at each branch inlet in real time;

[0008] S2. When the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to form a temporary bypass between the pressure relief chamber and the shared pressure relief channel.

[0009] S3. The airflow flowing into the pressure relief chamber is swirled and separated by a guide structure set in the pressure relief chamber, and the density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation.

[0010] S4. Monitor the oscillation frequency and amplitude of the vortex core during the swirling separation process within the pressure relief chamber;

[0011] S5. Determine the current venting stage based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, and adjust the outlet area of ​​the pressure relief chamber when the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset mode.

[0012] S6. After the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanism of other untriggered pressure relief valves in the shared pressure relief channel is put into the waiting state.

[0013] Furthermore, pressure monitoring points are installed at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure values ​​at each branch inlet in real time, including:

[0014] A piezoelectric pressure sensor is placed at the center of the flow channel at the branch inlet to collect the raw pressure signal;

[0015] A high-speed data acquisition circuit is used to continuously sample the raw pressure signal;

[0016] A high-pass filter is used to process the continuously sampled raw pressure signal to separate the dynamic pressure component, thereby obtaining the dynamic pressure value.

[0017] Furthermore, when the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to create a temporary bypass between the pressure relief chamber and the shared pressure relief channel, including:

[0018] Compare dynamic pressure values ​​with pressure thresholds;

[0019] When the dynamic pressure value continuously exceeds the pressure threshold for a predetermined duration, a trigger signal is generated;

[0020] The electromagnetic actuator of the pressure relief chamber is controlled to operate according to the trigger signal;

[0021] An electromagnetic actuator drives the isolation valve of the pressure relief chamber to open, creating a temporary bypass between the pressure relief chamber and the shared pressure relief channel.

[0022] Furthermore, the gas flow into the pressure relief chamber is swirled and separated by a guide structure installed within the chamber. The density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation, including:

[0023] A spiral guide vane fixed to the inlet section of the pressure relief chamber is used to accelerate the incoming airflow and guide it to form a rotating flow field;

[0024] Multiple static pressure detection points are arranged at different radial positions in the pressure relief chamber to collect the centrifugal pressure distribution formed by the rotating flow field;

[0025] The pressure difference between the central region and the sidewall region of the pressure relief chamber is calculated based on the centrifugal pressure distribution.

[0026] The enrichment of solid particles in the gas-solid two-phase flow is assessed by evaluating the pressure difference between the central region and the sidewall region of the pressure relief chamber, thereby analyzing the density distribution of the gas-solid two-phase flow.

[0027] Furthermore, calculating the pressure difference between the central region and the sidewall region of the pressure relief chamber based on the centrifugal pressure distribution includes: reading the pressure value of the static pressure detection point at the central axis position of the pressure relief chamber and the pressure value of the static pressure detection point in the sidewall region of the pressure relief chamber; inputting the pressure value of the static pressure detection point at the central axis position and the pressure value of the static pressure detection point in the sidewall region into the differential amplifier circuit; and outputting the pressure difference between the central region and the sidewall region of the pressure relief chamber through the differential amplifier circuit.

[0028] Furthermore, the oscillation frequency and amplitude of the vortex core during the swirling separation process are monitored within the pressure relief chamber, including:

[0029] A high-frequency dynamic pressure sensor is installed at the central axis of the pressure relief chamber to collect the original pressure fluctuation signal in the vortex core region.

[0030] Spectral analysis of the original pressure fluctuation signal is performed to identify the dominant oscillation frequency;

[0031] The oscillation amplitude is obtained by calculating the envelope of the original pressure fluctuation signal at the dominant oscillation frequency.

[0032] Furthermore, obtaining the oscillation amplitude by calculating the envelope of the original pressure fluctuation signal at the dominant oscillation frequency includes: performing a bandpass filter on the original pressure fluctuation signal with the dominant oscillation frequency as the center frequency; performing a Hilbert transform on the bandpass-filtered signal to calculate the analytic signal; and obtaining the envelope of the original pressure fluctuation signal at the dominant oscillation frequency by obtaining the modulus of the analytic signal, thereby determining the oscillation amplitude.

[0033] Furthermore, the current venting stage is determined based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, including the frequency drift and amplitude growth features. When the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset pattern, the outlet area of ​​the pressure relief chamber is adjusted, including:

[0034] The pressure difference between the central region and the sidewall region of the pressure relief chamber is compared with a preset pressure difference threshold to confirm the particulate matter concentration characteristics.

[0035] The time-domain variation trajectory of the dominant oscillation frequency is matched with a preset frequency drift pattern;

[0036] When the pressure difference between the central region and the sidewall region of the pressure relief chamber exceeds the preset pressure difference threshold and the time-domain change trajectory of the dominant oscillation frequency conforms to the preset frequency drift pattern, an area adjustment command is generated.

[0037] The stepper motor is controlled according to the area adjustment command to drive the regulating valve plate at the outlet of the pressure relief chamber, thereby changing the outlet area of ​​the pressure relief chamber.

[0038] Furthermore, comparing the pressure difference between the central region and the sidewall region of the pressure relief chamber with a preset pressure difference threshold to confirm the particulate matter concentration characteristics includes: inputting the pressure difference between the central region and the sidewall region of the pressure relief chamber output by the differential amplifier circuit into one input terminal of the analog comparator; inputting a reference voltage corresponding to the preset pressure difference threshold into the other input terminal of the analog comparator; when the analog comparator outputs a high-level signal, confirming that the particulate matter concentration characteristics meet the preset conditions.

[0039] Furthermore, after the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanisms that control other untriggered pressure relief valves in the shared pressure relief channel enter the ready-to-trigger state, including:

[0040] Receive the signal indicating that the outlet area adjustment of the pressure relief chamber of the stepper motor is complete;

[0041] The back pressure compensation mechanism's state switching command is generated based on the exit area adjustment completion signal.

[0042] The preloaded electromagnet of the back pressure compensation mechanism is energized according to the state switching command;

[0043] The back pressure compensation mechanism's compensation piston is moved to the pre-position by a preloaded electromagnet.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. By constructing a temporary bypass between the pressure relief chamber and the shared pressure relief channel, active guidance and energy dissipation of the initial venting airflow are achieved. When a battery module experiences thermal runaway and triggers its corresponding pressure relief valve, the dynamic pressure characteristics at the branch inlet can be captured in real time. By activating the pressure relief chamber, a controllable venting path is formed, which effectively diverts the high-speed airflow that would otherwise impact the shared pressure relief channel. This significantly reduces the peak dynamic back pressure in the shared pressure relief channel, thereby ensuring that other untriggered pressure relief valves can still respond normally under their preset pressure thresholds. By actively managing the fluid dynamics during the venting process, the problem of interference between multiple pressure relief units in the shared flow channel is fundamentally solved, maintaining the redundancy protection capability that the multi-stage triggering structure should have.

[0046] 2. By analyzing the gas-solid two-phase flow characteristics during the venting process, precise identification and adaptive control of the venting state are achieved. The density distribution of the gas-solid two-phase flow is analyzed using the centrifugal force field generated by swirling separation, and combined with the frequency and amplitude characteristics of vortex core oscillation, it is possible to accurately determine whether the current venting stage has entered the stage of violent combustion containing a large amount of solid particles. This criterion based on the fusion of multiple flow characteristics provides a precise basis for adjusting the outlet area of ​​the pressure relief chamber, ensuring that a matching venting capacity can be formed when facing thermal runaway events of different severity. At the same time, by coordinating the triggering state of the back pressure compensation mechanism, a system-level safety protection coordination mechanism is constructed, enabling the entire pressure relief system to achieve rapid pressure relief when facing single-point thermal runaway events, while also being fully prepared for possible chain reactions, greatly improving the overall safety margin of the battery pack system. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating a multi-stage triggering structure design method for a battery pack explosion relief valve according to the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Example: Figure 1 The present invention provides a multi-stage triggering structure design method for a battery pack explosion relief valve, which includes the following steps:

[0050] S1. Set up pressure monitoring points at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure value at each branch inlet in real time;

[0051] S2. When the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to form a temporary bypass between the pressure relief chamber and the shared pressure relief channel.

[0052] S3. The airflow flowing into the pressure relief chamber is swirled and separated by a guide structure set in the pressure relief chamber, and the density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation.

[0053] S4. Monitor the oscillation frequency and amplitude of the vortex core during the swirling separation process within the pressure relief chamber;

[0054] S5. Determine the current venting stage based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, and adjust the outlet area of ​​the pressure relief chamber when the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset mode.

[0055] S6. After the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanism of other untriggered pressure relief valves in the shared pressure relief channel is put into the waiting state.

[0056] S1. Set up pressure monitoring points at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure value at each branch inlet in real time. The specific implementation is as follows:

[0057] When setting up pressure monitoring points at the branch inlets of a shared pressure relief channel, a piezoelectric pressure sensor must first be placed at the center of the flow channel at each branch inlet. This piezoelectric pressure sensor is made of high-temperature resistant lead zirconate titanate ceramic material. Its sensing axis is parallel and aligned with the flow channel axis, and it is fixed to the flow channel wall via a threaded interface with a sealing gasket, ensuring that its sensing surface faces the incoming flow direction and is isolated from the fluid's inner boundary layer. This installation method ensures that the sensor directly senses the pressure pulsations of the fluid in the core area of ​​the flow channel, avoiding interference from wall turbulence. The sensor's operating temperature range covers, for example, from -40 degrees Celsius to 300 degrees Celsius, to adapt to the high-temperature gas environment that may be generated during battery thermal runaway. When subjected to pressure, the piezoelectric crystal inside the piezoelectric pressure sensor generates a charge signal proportional to the applied pressure. This charge signal is converted into a voltage signal by the sensor's built-in charge amplifier; this voltage signal is the acquired raw pressure signal. The gain coefficient of the charge amplifier can be adjusted according to the sensor's sensitivity, for example, set to 10 mV / kPa to ensure the output signal is within the effective range.

[0058] After the raw pressure signal is acquired, it is immediately transmitted to a high-speed data acquisition circuit for processing. This high-speed data acquisition circuit uses, for example, a 16-bit analog-to-digital converter with a sampling rate set to 100 kHz per channel. This sampling rate is set at least twice the highest pressure fluctuation frequency that may occur during the pressure relief process, according to the Nyquist sampling theorem. For example, assuming the highest pressure fluctuation frequency is 50 kHz, the sampling rate is at least 100 kHz to ensure that the transient pressure shock generated when the pressure relief valve opens can be captured without distortion. When the high-speed data acquisition circuit continuously samples the raw pressure signal, it uses a circular buffer storage method to continuously record the pressure data of the most recent two seconds. When the buffer is full, it automatically overwrites the oldest historical data. This continuous sampling mechanism ensures that when a pressure relief event is triggered at any time, complete basic pressure data before the event and complete dynamic process data during the event can be obtained. During the sampling process, the analog-to-digital converter converts the analog voltage signal into digital quantities. The value of each sampling point represents the instantaneous pressure value at that moment. These digital quantities arranged in a time sequence constitute the discretized representation of the raw pressure signal. The reference voltage of the analog-to-digital converter is set to, for example, ±5 volts, corresponding to a pressure measurement range, such as -100 kPa to +100 kPa, to ensure that the signal does not saturate.

[0059] After obtaining the continuously sampled raw pressure signal, a high-pass filter is used to process the signal to separate the dynamic pressure component. A fourth-order Butterworth high-pass filter is used, with a cutoff frequency set to, for example, 0.5 Hz. This cutoff frequency is determined based on the analysis of the pressure fluctuation characteristics under normal battery pack operation. During normal operation, the pressure change frequency is mostly lower than this value, while the effective dynamic pressure component frequency generated when the pressure relief valve operates is higher than this value. In the filter design process, the continuously sampled raw pressure signal is first subjected to zero-phase filtering, that is, the signal is first forward filtered, and then the filtering result is reversed for backward filtering to eliminate phase distortion. During the filtering process, the pressure value of each sampling point is substituted into the difference equation for iterative calculation. The form of the difference equation is obtained based on the discretization of the filter transfer function. For example, the bilinear transform method is used to convert the analog filter into a digital filter. The calculation involves the output value of the previous sampling point and the current and historical input values, removing the DC component and low-frequency drift component from the signal point by point. After processing by a high-pass filter, the output signal is the pure dynamic pressure component. This dynamic pressure component directly reflects the rapid fluctuation characteristics of the airflow pressure during the pressure relief process, thus obtaining the final dynamic pressure value used to determine the triggering timing of the pressure relief valve. The dimension of this dynamic pressure value is kPa, and its numerical range is, for example, -50 kPa to +50 kPa, corresponding to the maximum pressure fluctuation range that may occur during the pressure relief process. In the calculation of the dynamic pressure value, the processing of each sampling point is based on the output of the previous step, ensuring a consistent data flow.

[0060] S2. When the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to create a temporary bypass between the pressure relief chamber and the shared pressure relief channel. Specifically, the implementation is as follows:

[0061] This step involves the specific control logic and execution process for activating the pressure relief chamber when abnormal pressure is detected. The comparison between the dynamic pressure value and the pressure threshold is achieved through an analog comparator circuit. This circuit uses an integrated circuit, whose inverting input receives the dynamic pressure signal from the output of a high-pass filter. This signal is in voltage form, with the dimension of volts, corresponding to the pressure unit kilopascal (kPa). The conversion ratio is, for example, 10 millivolts per kPa. A stable reference voltage is connected to the non-inverting input. The value of this reference voltage corresponds to a preset pressure threshold. The reference voltage is set by a precision potentiometer, for example, set to 0.2 volts, corresponding to a pressure threshold of 20 kPa. The pressure threshold is set based on battery pack safety design specifications. Typical amplitudes of pressure fluctuations generated in the early stages of thermal runaway are experimentally determined. For example, in multiple tests, the maximum dynamic pressure value during normal operation was 5 kPa, while the dynamic pressure value in the early stages of thermal runaway exceeded 15 kPa. Therefore, the threshold is set to 20 kPa to provide a safety margin and avoid false triggering. The analog comparator circuit continuously compares the instantaneous voltage of the dynamic pressure value with the reference voltage. When the voltage of the dynamic pressure value exceeds the reference voltage, the analog comparator circuit outputs a high level, such as 5 volts; otherwise, it remains at a low level of 0 volts, and the output signal is sent to the subsequent timing unit.

[0062] When the dynamic pressure value continuously exceeds the pressure threshold for a predetermined duration, a trigger signal is generated via digital logic circuitry. This digital logic circuitry is based on a programmable timer chip, such as the NE555, configured in monostable mode. The high and low level signals output from the analog comparator circuit are fed to the trigger pin of the programmable timer. The programmable timer starts timing when it detects the input signal changing from low to high and continuously monitors the duration the input signal remains high. The predetermined duration is set to avoid false triggering; for example, it is set to 10 milliseconds. This duration is much longer than the time it takes for the threshold to be accidentally exceeded during normal pressure fluctuations (e.g., the time exceeding the threshold during normal fluctuations is typically less than 1 millisecond), but shorter than the critical response time for thermal runaway pressure growth (e.g., the thermal runaway pressure rise time is typically greater than 50 milliseconds). The programmable timer uses a crystal oscillator to provide a time reference, such as a 10 MHz crystal oscillator. It uses a counter to count clock cycles to achieve precise timing. The counter is initially zero and increments by one for each clock cycle received. When the counter value reaches a preset value, such as 100000 corresponding to 10 milliseconds, the programmable timer outputs a rising edge signal as a trigger signal. This trigger signal is a standard digital pulse signal with a pulse width of, for example, 1 microsecond and a voltage level of 5 volts.

[0063] The electromagnetic actuator controlling the pressure relief chamber's operation based on the trigger signal is achieved through a drive circuit, which includes a power amplifier stage and a protection circuit. The trigger signal is fed into a power amplifier circuit employing an operational amplifier and a metal-oxide-semiconductor (MOSFET) combination. The operational amplifier, such as an LM358, amplifies the weak digital pulse signal to an intermediate voltage. The MOSFET, such as an IRF540, acts as a switching element; when its gate receives the amplified trigger signal, conduction occurs between its source and drain, applying a 24-volt operating voltage to the electromagnetic actuator's coil. The electromagnetic actuator uses a solenoid structure with, for example, 500 turns, a wire diameter of 0.5 mm, and a coil resistance of 10 ohms. When energized, it generates current according to Ohm's law; for example, 2.4 amps when 24 volts are applied. The magnetic flux is calculated according to Ampere's law, achieving a magnetic flux density of, for example, 0.8 Tesla, generating sufficient electromagnetic force to drive the magnetic core. The drive circuit also includes overcurrent protection, such as a 3-amp fuse connected in series to prevent short-circuit damage to the coil.

[0064] The opening of the isolation valve in the pressure relief chamber, driven by an electromagnetic actuator, temporarily bypasses the pressure relief chamber and the shared pressure relief channel via a mechanical transmission mechanism. The electromagnetic actuator's core is threadedly connected to the valve stem of the isolation valve. The core is made of soft iron, and the valve stem is made of stainless steel. When the coil is energized, generating a magnetic field, the core moves along its axis under the influence of the magnetic field. The movement distance is, for example, 8 mm. The movement speed depends on the balance between the electromagnetic force and the spring force. For example, at a current of 2.4 amps, the electromagnetic force is 50 N, the spring preload is 20 N, and the net acceleration is 30 N divided by the core mass of 0.1 kg, which equals 300 m / s². The time required to move 8 mm is approximately 7.3 milliseconds. The isolation valve uses a lift valve structure, with the valve seat integrated with the wall of the shared pressure relief channel. The valve core is made of high-temperature resistant polyetheretherketone (PEEK) material and maintains a seal in the closed state through spring pressure. The spring stiffness is, for example, 10 N / mm. When the electromagnetic actuator drives the valve core to move, the isolation valve changes from a closed state to an open state. The opening area is, for example, 150 square millimeters, forming a sufficient flow cross-section. The flow coefficient is calculated as the opening area multiplied by the velocity coefficient 0.8, which equals 120 square millimeters. The pressure relief chamber is connected to the shared pressure relief channel through this open isolation valve, forming a temporary bypass. This allows high-speed airflow to be diverted from the shared pressure relief channel to the pressure relief chamber, thereby reducing the dynamic back pressure within the shared pressure relief channel. Throughout the entire operation, the total time from trigger signal generation to the complete opening of the isolation valve is controlled, for example, within 15 milliseconds, including a 2-millisecond signal transmission delay, a 7.3-millisecond electromagnetic response, and a 5.7-millisecond mechanical movement, ensuring a rapid response to thermal runaway events. Anomaly handling includes monitoring the electromagnetic actuator current. If the abnormal current exceeds 3 amps, the power supply is cut off via the drive circuit, and the backup mechanism is triggered.

[0065] S3. The airflow flowing into the pressure relief chamber is swirled and separated by a guide structure installed in the pressure relief chamber. The density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation. The specific implementation is as follows:

[0066] When a spiral guide vane fixed to the inlet section of the pressure relief chamber is used to accelerate the incoming airflow and guide it to form a rotating flow field, the spiral guide vane is made of stainless steel plate with a thickness of, for example, 2 mm. Its spiral angle is set to, for example, 45 degrees. The height of the guide vane is consistent with the height of the flow channel in the inlet section of the pressure relief chamber, for example, 30 mm. The number of guide vanes is, for example, 4, evenly distributed circumferentially. The spiral guide vane is fixed to the inner wall of the inlet section of the pressure relief chamber by welding. Its inlet edge is flush with the inlet end face of the pressure relief chamber, and its outlet edge extends to the starting position of the cylindrical section of the pressure relief chamber. When the airflow passes through the spiral guide vane, the cross-sectional area of ​​the flow channel gradually decreases, the flow velocity increases, and at the same time, it generates a tangential velocity component guided by the spiral surface, forming a strong rotating flow field. The rotation intensity is determined by the geometric parameters of the spiral guide vane. For example, with a spiral angle of 45 degrees, the ratio of tangential velocity to axial velocity is approximately 1, which can generate sufficient centrifugal force for gas-solid separation.

[0067] When multiple static pressure detection points are arranged at different radial positions within the pressure relief chamber to collect the centrifugal pressure distribution formed by the rotating flow field, the static pressure detection points include one static pressure detection point located at the central axis of the pressure relief chamber and four static pressure detection points located in the sidewall region of the pressure relief chamber. The static pressure detection points in the sidewall region are uniformly distributed circumferentially on the same cross-section, which is, for example, 100 mm away from the outlet end face of the spiral guide vane. Each static pressure detection point consists of a pressure tapping hole with a diameter of, for example, 1 mm and a pressure guiding tube connected to it. The axis of the pressure tapping hole is perpendicular to the inner wall of the pressure relief chamber. The pressure guiding tube has a uniform length of, for example, 200 mm, an inner diameter of 2 mm, and is made of stainless steel. The other end of the pressure guiding tube is connected to a piezoresistive pressure sensor with a range of, for example, 0 to 100 kPa, an accuracy of 0.1 kPa, and a sampling frequency of 100 Hz. By simultaneously reading the pressure values ​​of the static pressure detection points at the central axis and the static pressure detection points in the sidewall region of the pressure relief chamber, the radial pressure distribution characteristics of the rotating flow field are obtained. In a strong rotating flow field, the pressure in the sidewall region is higher than that in the central region, and the magnitude of the pressure difference reflects the rotation intensity.

[0068] The pressure difference between the central and sidewall regions of the pressure relief chamber, calculated based on centrifugal pressure distribution, is achieved using a differential amplifier circuit. When reading the pressure values ​​at the static pressure detection points along the central axis and those along the sidewall regions of the pressure relief chamber, the pressure value at the central axis is converted into a voltage signal by a pressure sensor, while the pressure values ​​at the sidewall regions are converted into voltage signals by four other pressure sensors. The output signals from these four sidewall sensors are then averaged using an averaging circuit to obtain a voltage signal representing the average pressure in the sidewall regions. When the pressure values ​​at the central axis and sidewall regions are input to the differential amplifier circuit, the output signal from the pressure sensor at the central axis is connected to the inverting input, while the average pressure signal from the sidewall regions is connected to the non-inverting input. The differential amplifier circuit uses an instrumentation amplifier with a gain resistor set to, for example, 100 kΩ, corresponding to a gain of 5. The input signal voltage range is 0 to 5 volts, corresponding to a pressure range of 0 to 50 kPa. When the differential amplifier circuit outputs the pressure difference between the center region and the side wall region of the pressure relief chamber, it amplifies the difference between the two input signals and outputs a voltage signal proportional to the pressure difference. For example, when the actual pressure difference is 10 kPa, the input signal difference is 1 volt, and after amplification, a 5 volt voltage signal is output. The pressure difference range is 0 to 50 kPa, and the output voltage range is 0 to 5 volts.

[0069] The enrichment degree of solid particles in a gas-solid two-phase flow is assessed by evaluating the pressure difference between the central and side regions of the pressure relief chamber, thus analyzing the density distribution of the gas-solid two-phase flow based on the principle of centrifugal separation. In a rotating flow field, solid particles move towards the side regions under the action of centrifugal force, leading to an increase in particle concentration in the side regions and a decrease in particle concentration in the central region. The density distribution of the gas-solid two-phase flow exhibits a characteristic of high density in the side regions and low density in the central region. There is a quantitative relationship between the pressure difference between the central and side regions of the pressure relief chamber and the degree of particle enrichment; an increase in pressure difference indicates an increase in particle concentration in the side regions, i.e., a higher degree of particle enrichment. Experimental calibration can obtain the correlation between pressure difference and particle concentration. For example, under standard operating conditions, a pressure difference of 5 kPa corresponds to a particle volume fraction of 10% in the side regions, and a pressure difference of 10 kPa corresponds to a particle volume fraction of 20% in the side regions. During the evaluation process, the differential pressure signal output from the differential amplifier circuit is compared with the calibration curve, and the differential pressure value is converted into an index of particulate matter enrichment. For example, when the differential pressure reaches 8 kPa, the particulate matter enrichment level is judged to be moderate. Based on the particulate matter enrichment analysis results, combined with the total volumetric flow rate data of the gas-solid two-phase flow, the density distribution at different radial positions within the pressure relief chamber can be calculated. For example, the density in the central region is close to the density of pure gas, while the density in the sidewall region is the sum of the gas density and the apparent density of particulate matter, thus completing a quantitative analysis of the density distribution of the gas-solid two-phase flow.

[0070] S4. Monitor the oscillation frequency and amplitude of the vortex core during the swirling separation process within the pressure relief chamber. Specifically, this is implemented as follows:

[0071] When a high-frequency dynamic pressure sensor is installed at the central axis of the pressure relief chamber to acquire the original pressure fluctuation signal in the vortex core region, a piezoelectric sensor is used, such as the PCB 113B26 model. Its natural frequency is 500 kHz, the range is 0 to 100 kPa, and the linearity error is less than 2% of full scale. The sensor is fixed to the central axis of the pressure relief chamber via a threaded mounting hole with a diameter of 6 mm. A copper gasket is used for sealing to ensure airtightness. The sensor's sensing surface is flush with the inner wall of the pressure relief chamber to avoid disturbing the flow. During operation, the internal piezoelectric crystal of the high-frequency dynamic pressure sensor converts pressure fluctuations into an electric charge signal. This charge signal is then converted into a voltage signal by a built-in charge amplifier, with a voltage output range of 0 to 5 volts, corresponding to a pressure of 0 to 100 kPa. During acquisition, the sampling frequency is set to 1 MHz to satisfy the Nyquist sampling theorem, ensuring the capture of high-frequency pressure fluctuations in the vortex core region. The original pressure fluctuation signal is output in the form of a voltage time series. Each sampling point represents the instantaneous pressure value at that moment. The signal length is, for example, 1 second, containing 1,000,000 data points.

[0072] To identify the dominant oscillation frequency, the original pressure fluctuation signal is first preprocessed, including DC component removal and windowing. DC component removal is achieved by calculating the signal's average value and subtracting it. The windowing process uses a Hanning window with a length of 1024 sampling points and an overlap rate of 50% to reduce spectral leakage. Spectral analysis employs a Fast Fourier Transform (FFT) algorithm to convert the time-domain signal into a frequency-domain representation. The FFT points are set to 1024, and the frequency resolution is the sampling frequency divided by the number of points; for example, 1 MHz divided by 1024 is approximately 976 Hz. The power spectral density is obtained after the transform, and the dominant oscillation frequency is identified by finding peak values ​​in the power spectral density. Peak detection is achieved by comparing the power value of each frequency point with the power values ​​of its adjacent points. When the power value of a frequency point is greater than the power values ​​of the five points before and after it, that frequency point is considered a peak. The dominant oscillation frequency is selected as the frequency corresponding to the highest peak in the power spectral density. For example, if a peak is detected at 5000 Hz and the power value is more than 20% higher than the second highest peak, then the dominant oscillation frequency is determined to be 5000 Hz. During the spectral analysis, the frequency range is limited to 0 to half of the sampling frequency, i.e., 0 to 500 kHz, to exclude aliasing components.

[0073] When obtaining the oscillation amplitude by calculating the envelope of the original pressure fluctuation signal at the dominant oscillation frequency, the original pressure fluctuation signal is first bandpass filtered with the dominant oscillation frequency as the center frequency. A fourth-order Butterworth filter is used, with its center frequency set to the identified dominant oscillation frequency, for example, 5000 Hz, and its bandwidth set to, for example, 1000 Hz, i.e., a passband range of 4500 Hz to 5500 Hz. The filter design uses the bilinear transform method to convert the analog filter into a digital filter. During the filtering process, the difference equation is applied point-by-point to calculate the original pressure fluctuation signal, and the coefficients of the difference equation are determined according to the filter transfer function. The filtered output signal retains the components near the dominant oscillation frequency and removes interference from other frequencies. A Hilbert transform is then performed on the bandpass-filtered signal to calculate the analytic signal. The Hilbert transform is achieved by convolving the signal with a Hilbert kernel, which is an infinitely long sequence. In practical applications, a finite-length filter is used as an approximation, such as a 51-point FIR filter, and the filter coefficients are calculated based on a sine function. During convolution, the bandpass-filtered signal is multiplied and added with a Hilbert kernel to obtain the Hilbert transform. The analytic signal is composed of the bandpass-filtered signal as the real part and the Hilbert transform result as the imaginary part, making it a complex sequence. The envelope of the original pressure fluctuation signal at the dominant oscillation frequency is obtained by acquiring the modulus of the analytic signal. The modulus of the analytic signal is calculated as the square root of the sum of the squares of the real and imaginary parts, calculated independently for each sampling point. The resulting envelope is a time-domain signal, and its amplitude represents the oscillation amplitude. For example, an average envelope amplitude of 2 volts corresponds to a pressure amplitude of 20 kPa. The oscillation amplitude is determined by calculating half the difference between the maximum and minimum values ​​of the envelope signal within a complete cycle. For example, if the maximum value of the envelope is 3 volts and the minimum value is 1 volt, the oscillation amplitude is 1 volt, corresponding to a pressure amplitude of 10 kPa.

[0074] S5. Based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, the current venting stage is determined. When the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset pattern, the outlet area of ​​the pressure relief chamber is adjusted. Specifically, the implementation is as follows:

[0075] When comparing the pressure difference between the central and sidewall regions of the pressure relief chamber with a preset pressure difference threshold to confirm particulate matter concentration characteristics, the preset pressure difference threshold is set based on experimental data. By measuring the pressure difference between the central and sidewall regions of the pressure relief chamber at different particulate matter concentrations, a correspondence between pressure difference and particulate matter concentration is established. For example, when the particulate matter volume fraction reaches 15%, the corresponding pressure difference is 8 kPa; therefore, the preset pressure difference threshold is set to 8 kPa. The comparison process is implemented using an analog comparator. The pressure difference between the central and sidewall regions of the pressure relief chamber, output from the differential amplifier circuit, is input to one input terminal of the analog comparator. This input signal is in voltage form, with the dimension of volts, corresponding to the pressure difference unit of kilopascals, and a conversion ratio, for example, 0.5 volts per kilopascal. A reference voltage corresponding to the preset pressure difference threshold is generated by a precision voltage source; for example, a preset pressure difference threshold of 8 kPa corresponds to a reference voltage of 4 volts, which is input to the other input terminal of the analog comparator. The output level of the analog comparator is determined by the voltage difference between the two input terminals. When the pressure difference input voltage exceeds the reference voltage, the analog comparator outputs a high-level signal, for example, 5 volts; otherwise, it outputs a low-level signal, 0 volts. When the analog comparator outputs a high-level signal, it confirms that the particulate matter concentration characteristics meet the preset conditions, indicating that the enrichment of particulate matter in the gas-solid two-phase flow has reached the level that requires adjustment of the outlet area.

[0076] When matching the time-domain variation trajectory of the dominant oscillation frequency with a preset frequency drift pattern, the time-domain variation trajectory of the dominant oscillation frequency is obtained by continuously recording the dominant oscillation frequency values ​​at multiple time points. For example, the dominant oscillation frequency is recorded every 10 milliseconds, and 100 data points are obtained by recording continuously for 1 second, forming the time-domain variation trajectory. The preset frequency drift pattern is defined as a pattern in which the frequency monotonically increases with time, specifically including the process of the frequency gradually rising from an initial value to a stable value. For example, the initial frequency is 5000 Hz, and it linearly increases to 6000 Hz within 1 second. The matching process uses correlation coefficient calculation. The time-domain variation trajectory of the dominant oscillation frequency is linearly correlated with the preset frequency drift pattern, and the Pearson correlation coefficient is calculated. The correlation coefficient threshold is set to, for example, 0.8. When the actual correlation coefficient exceeds 0.8, the match is considered successful. During the calculation, the two sequences are standardized by subtracting the mean and dividing by the standard deviation. Then, the sum of the products of corresponding points is calculated and divided by the number of data points minus one to obtain the correlation coefficient. The matching result is output through digital logic circuitry. When the correlation coefficient exceeds the threshold, a high-level signal is output.

[0077] When the pressure difference between the central region and the sidewall region of the pressure relief chamber exceeds a preset pressure difference threshold and the time-domain variation trajectory of the dominant oscillation frequency conforms to a preset frequency drift pattern, the area adjustment command is generated through an AND gate logic circuit. The high-level signal output from the analog comparator and the high-level signal output from the frequency matching circuit are simultaneously input to an AND gate. The AND gate outputs a high level when both inputs are high, otherwise it outputs a low level. When the output is high, a monostable multivibrator is triggered, for example, using an NE555 chip configured in monostable mode, generating a fixed-width pulse signal as the area adjustment command. The pulse width is, for example, 100 microseconds, and the voltage level is 5 volts. The area adjustment command is electrically isolated through an optocoupler to prevent interference. The input side of the optocoupler receives the area adjustment command, and the output side generates an isolated digital signal.

[0078] The stepper motor drives the regulating valve plate at the outlet of the pressure relief chamber according to the area adjustment command. When the outlet area of ​​the pressure relief chamber is changed, the area adjustment command is sent to the stepper motor driver. The stepper motor driver generates a pulse sequence and direction signal based on the area adjustment command. The pulse frequency determines the stepper motor speed; for example, it is set to 1000 Hz, with each pulse corresponding to a 1.8-degree rotation of the stepper motor. The stepper motor is a two-phase hybrid stepper motor with a holding torque of 0.4 Nm. The stepper motor is connected to the lead screw of the regulating valve plate via a coupling. The lead screw pitch is set to, for example, 2 mm. For every revolution of the stepper motor, the regulating valve plate moves 2 mm. The regulating valve plate is made of stainless steel, is circular in shape, and has a diameter of, for example, 50 mm. The outlet area is changed by adjusting the overlap distance between the regulating valve plate and the valve seat. The outlet area is calculated as a function of the displacement of the regulating valve plate; for example, when the regulating valve plate moves 5 mm, the outlet area increases from 0 square millimeters when fully closed to 500 square millimeters. The stepper motor driver also includes a current control circuit that sets the phase current to 80% of the rated current, such as 1.5 amps, to ensure sufficient torque. Throughout the adjustment process, the stepper motor moves a corresponding number of steps based on the number of pulses received in the area adjustment command. For example, receiving 500 pulses results in a 900-degree rotation, corresponding to a 5-millimeter movement of the regulating valve plate, and a 500 square millimeter change in the outlet area. Position feedback is achieved through the stepper motor driver's built-in counter, which records the number of pulses sent to ensure displacement accuracy.

[0079] S6. After the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanism of other untriggered pressure relief valves in the shared pressure relief channel is put into the ready-to-trigger state. The specific implementation is as follows:

[0080] The signal indicating that the outlet area adjustment of the pressure relief chamber is complete is received from the stepper motor via the digital output interface of the stepper motor driver. After receiving a certain number of pulses, the stepper motor driver's internal position counter reaches a preset value. At this point, the driver outputs a digital signal as the pressure relief chamber outlet area adjustment completion signal through an open-collector output circuit. This signal is a high-level active switching signal with a voltage level of 24V DC and a duration of at least 100 milliseconds. Signal transmission uses twisted-pair shielded cable with an impedance of 100 ohms and a transmission distance not exceeding 10 meters. At the signal receiving end, electrical isolation is achieved through an optocoupler isolator. A 2kΩ current-limiting resistor is connected in series on the input side of the optocoupler, and a 5V logic level signal is provided on the output side. This logic signal is sent to the general-purpose input / output pin of the microcontroller. The microcontroller detects the pin level status through polling, and when a high level is detected, it is confirmed as a valid pressure relief chamber outlet area adjustment completion signal.

[0081] The generation of the state switching command for the back pressure compensation mechanism based on the outlet area adjustment completion signal is implemented through the microcontroller's logic processing program. After confirming receipt of the outlet area adjustment completion signal from the pressure relief chamber, the microcontroller initiates a delay program with a delay time set to 50 milliseconds to ensure the complete stability of the preceding actions. After the delay, the microcontroller reads the pre-stored instruction code from its program memory; this instruction code corresponds to the state switching command for the back pressure compensation mechanism. During instruction generation, the microcontroller first checks the status of other untriggered pressure relief valves in the shared pressure relief channel, confirming their untriggered state by reading the status register of each pressure relief valve. The state switching command includes the address code of the target back pressure compensation mechanism, the operation type code, and timestamp information. The instruction length is 4 bytes, using Manchester encoding format. The command is sent to the instruction distribution circuit via the microcontroller's serial peripheral interface at a transmission rate of 1 megabit per second.

[0082] The energization of the preloaded electromagnet of the back pressure compensation mechanism, driven by a state switching command, is accomplished through a power drive circuit. Upon receiving the state switching command, the command distribution circuit first decodes the address to identify the target back pressure compensation mechanism. Each preloaded electromagnet in the back pressure compensation mechanism has an independent drive circuit, employing a half-bridge topology and using two metal-oxide-semiconductor (MOSFETs) as switching elements. When the operation type code in the state switching command indicates that energization is required, the upper MOSFET of the drive circuit turns on, and the lower MOSFET turns off, applying a 24V DC power supply to the coil of the preloaded electromagnet. The drive circuit includes a 0.1-ohm current sampling resistor. By monitoring the voltage across the sampling resistor, the output current is controlled in real time to ensure that the current remains stable within ±5% of the rated value. The coil inductance of the preloaded electromagnet is 50 millihenries, and the resistance is 8 ohms. At 24V, the steady-state current is 3 amps. A soft-start method is used during startup, with the current rise time controlled within 10 milliseconds.

[0083] The back pressure compensation mechanism's piston is moved to the pre-position by a pre-loaded electromagnet through a combination of electromagnetic force and mechanical structure. When energized, the pre-loaded electromagnet generates an electromagnetic field; the magnetic field strength is proportional to the current, producing a magnetic flux density of 0.6 Tesla at 3 amperes. The electromagnetic force acts on the soft iron core of the compensation piston, which is threadedly connected to the piston, with a core travel of 15 mm. Under the action of the electromagnetic force, the compensation piston overcomes the preload of the return spring, which has a stiffness of 20 N / mm and a preload of 100 N / mm. When the electromagnetic force exceeds the spring preload, the compensation piston begins to move towards the pre-position at a speed of 200 mm / s. The pre-position is determined by a mechanical limit block, which is adjustable with an adjustment accuracy of 0.1 mm. When the compensation piston reaches the pre-position, a position sensor is triggered to generate a confirmation signal. This position sensor, a Hall effect sensor, is installed 0.5 mm from the pre-position. When the permanent magnet on the compensation piston passes the Hall effect sensor, the sensor's output level changes. This signal is fed back to the control circuit to confirm that the back pressure compensation mechanism has entered the ready-to-trigger state. The entire movement process is controlled within 100 milliseconds, including a 30-millisecond electromagnet response time and a 70-millisecond mechanical movement time.

[0084] All calculations involved in the embodiments are dimensionless numerical calculations, and the preset parameters and thresholds in the calculations are set by those skilled in the art according to the actual situation.

[0085] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0086] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and inventive constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0087] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0088] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0089] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0090] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-stage triggering structure design method for a battery pack explosion relief valve, characterized in that, Includes the following steps: S1. Set up pressure monitoring points at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure value at each branch inlet in real time; S2. When the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to form a temporary bypass between the pressure relief chamber and the shared pressure relief channel. S3. The airflow flowing into the pressure relief chamber is swirled and separated by a guide structure set in the pressure relief chamber, and the density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation. S4. Monitor the oscillation frequency and amplitude of the vortex core during the swirling separation process within the pressure relief chamber; S5. Determine the current venting stage based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, and adjust the outlet area of ​​the pressure relief chamber when the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset mode. S6. After the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanism of other untriggered pressure relief valves in the shared pressure relief channel is put into the waiting state.

2. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, Pressure monitoring points are installed at each branch inlet of the shared pressure relief channel to monitor the dynamic pressure values ​​at each branch inlet in real time, including: A piezoelectric pressure sensor is placed at the center of the flow channel at the branch inlet to collect the raw pressure signal; A high-speed data acquisition circuit is used to continuously sample the raw pressure signal; A high-pass filter is used to process the continuously sampled raw pressure signal to separate the dynamic pressure component, thereby obtaining the dynamic pressure value.

3. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, When the dynamic pressure value at any pressure monitoring point reaches the pressure threshold, the pressure relief chamber at the corresponding branch inlet is activated to create a temporary bypass between the pressure relief chamber and the shared pressure relief channel, including: Compare dynamic pressure values ​​with pressure thresholds; When the dynamic pressure value continuously exceeds the pressure threshold for a predetermined duration, a trigger signal is generated; The electromagnetic actuator of the pressure relief chamber is controlled to operate according to the trigger signal; An electromagnetic actuator drives the isolation valve of the pressure relief chamber to open, creating a temporary bypass between the pressure relief chamber and the shared pressure relief channel.

4. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, The gas flow into the pressure relief chamber is swirled and separated by a guide structure installed within the chamber. The density distribution of the gas-solid two-phase flow is analyzed based on the centrifugal force field generated by the swirling separation, including: A spiral guide vane fixed to the inlet section of the pressure relief chamber is used to accelerate the incoming airflow and guide it to form a rotating flow field; Multiple static pressure detection points are arranged at different radial positions in the pressure relief chamber to collect the centrifugal pressure distribution formed by the rotating flow field; The pressure difference between the central region and the sidewall region of the pressure relief chamber is calculated based on the centrifugal pressure distribution. The enrichment of solid particles in the gas-solid two-phase flow is assessed by evaluating the pressure difference between the central region and the sidewall region of the pressure relief chamber, thereby analyzing the density distribution of the gas-solid two-phase flow.

5. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 4, characterized in that, Calculating the pressure difference between the central region and the sidewall region of the pressure relief chamber based on centrifugal pressure distribution includes: reading the pressure value of the static pressure detection point at the central axis position of the pressure relief chamber and the pressure value of the static pressure detection point in the sidewall region of the pressure relief chamber; inputting the pressure value of the static pressure detection point at the central axis position and the pressure value of the static pressure detection point in the sidewall region into the differential amplifier circuit; and outputting the pressure difference between the central region and the sidewall region of the pressure relief chamber through the differential amplifier circuit.

6. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, Monitoring the oscillation frequency and amplitude of the vortex core during swirling separation within the pressure relief chamber, including: A high-frequency dynamic pressure sensor is installed at the central axis of the pressure relief chamber to collect the original pressure fluctuation signal in the vortex core region. Spectral analysis of the original pressure fluctuation signal is performed to identify the dominant oscillation frequency; The oscillation amplitude is obtained by calculating the envelope of the original pressure fluctuation signal at the dominant oscillation frequency.

7. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 6, characterized in that, The process of obtaining the oscillation amplitude by calculating the envelope of the original pressure fluctuation signal at the dominant oscillation frequency includes: performing a bandpass filter on the original pressure fluctuation signal with the dominant oscillation frequency as the center frequency; performing a Hilbert transform on the bandpass-filtered signal to calculate the analytic signal; and obtaining the envelope of the original pressure fluctuation signal at the dominant oscillation frequency by obtaining the modulus of the analytic signal, thereby determining the oscillation amplitude.

8. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, The current venting stage is determined based on the density distribution and oscillation characteristics of the gas-solid two-phase flow, including frequency drift and amplitude growth. When the density distribution meets the preset particulate concentration characteristics and the frequency drift meets the preset pattern, the outlet area of ​​the pressure relief chamber is adjusted, including: The pressure difference between the central region and the sidewall region of the pressure relief chamber is compared with a preset pressure difference threshold to confirm the particulate matter concentration characteristics. The time-domain variation trajectory of the dominant oscillation frequency is matched with a preset frequency drift pattern; When the pressure difference between the central region and the sidewall region of the pressure relief chamber exceeds the preset pressure difference threshold and the time-domain change trajectory of the dominant oscillation frequency conforms to the preset frequency drift pattern, an area adjustment command is generated. The stepper motor is controlled according to the area adjustment command to drive the regulating valve plate at the outlet of the pressure relief chamber, thereby changing the outlet area of ​​the pressure relief chamber.

9. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 8, characterized in that, The process of comparing the pressure difference between the center region and the sidewall region of the pressure relief chamber with a preset pressure difference threshold to confirm the particulate matter concentration characteristics includes: inputting the pressure difference between the center region and the sidewall region of the pressure relief chamber output by the differential amplifier circuit into one input terminal of the analog comparator; inputting a reference voltage corresponding to the preset pressure difference threshold into the other input terminal of the analog comparator; and confirming that the particulate matter concentration characteristics meet the preset conditions when the analog comparator outputs a high-level signal.

10. The multi-stage triggering structure design method for a battery pack explosion relief valve according to claim 1, characterized in that, After the outlet area of ​​the pressure relief chamber is adjusted, the back pressure compensation mechanisms of other untriggered pressure relief valves in the shared pressure relief channel enter the ready-to-trigger state, including: Receive the signal indicating that the outlet area adjustment of the pressure relief chamber of the stepper motor is complete; The back pressure compensation mechanism's state switching command is generated based on the exit area adjustment completion signal. The preloaded electromagnet of the back pressure compensation mechanism is energized according to the state switching command; The back pressure compensation mechanism's compensation piston is moved to the pre-position by a preloaded electromagnet.

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