A control method and device for a high-acceleration stress test device

Abstract

The application discloses a control method and equipment of a high-accelerated stress test device, and belongs to the field of environmental test equipment. The control method comprises the following steps: keeping the exhaust valve in an open state during the temperature rising stage of the test cavity; monitoring the exhaust temperature detected by the temperature sensor arranged on the exhaust passage of the exhaust valve in real time; judging whether the exhaust temperature reaches the preset trigger temperature determined based on the target humidity; when the exhaust temperature reaches the preset trigger temperature, closing the exhaust valve, making the test cavity enter a closed state and starting to build the test pressure. By introducing the exhaust temperature sensor, the application takes the exhaust temperature as a direct indicator of the steam saturation state, dynamically adjusts the preset trigger temperature according to the target humidity, realizes the accurate control of the closing time of the exhaust valve, avoids the pressure fluctuation and steam condensation problem caused by the fixed delay, and significantly improves the consistency of the test conditions and the reliability of the test data between batches.

Description

Technical Field

[0001] This invention relates to the field of environmental testing equipment, and more particularly to a control method and equipment for a high-acceleration stress testing device. Background Technology

[0002] Highly Accelerated Stress Test (HAST) is an accelerated aging test technology widely used for reliability assessment of products such as electronic components, semiconductor packaging, and polymer materials. It creates a harsh environment of high temperature, high humidity, and high pressure within a test chamber, causing internal or surface failures in the product that are equivalent to long-term use within a short period, thus significantly shortening the product reliability verification cycle. In this test, pressure is the core physical parameter for achieving a specific saturated water vapor environment and thus precisely controlling relative humidity. Therefore, the accuracy and consistency of the pressure establishment process are fundamental prerequisites for ensuring effective test conditions and comparable results.

[0003] Currently, mainstream HAST equipment generally adopts an open-loop strategy based on a fixed time sequence for pressure control during the heating phase. Its typical operation is as follows: when the dry bulb temperature rises to a certain preset temperature (generally slightly lower than the target temperature), the system starts a fixed delay timer (e.g., 5-10 minutes); after the delay ends, regardless of the actual thermodynamic state inside the chamber, the exhaust valve is closed, causing the system to switch to closed-loop pressurization.

[0004] However, the control logic of this method has significant limitations: its action triggering relies on a fixed delay, completely decoupled from key parameters reflecting whether the system has reached steam saturation (especially wet-bulb temperature). Because the initial humidity, water volume, load, and heating response vary in each test, the time it takes for the wet-bulb temperature to reach the target saturation value will inevitably fluctuate. The fixed delay mechanism cannot adapt to this fluctuation. If the exhaust valve is closed too early before the wet-bulb temperature reaches the target, insufficient steam and low pressure will result; if it is delayed in closing after the wet-bulb temperature has reached the target, steam loss and pressure build-up will be delayed. This directly leads to a decrease in the repeatability of pressure build-up curves between different test batches, affecting the consistency of test conditions and thus limiting the reliability of the test data.

[0005] It should be noted that the above description of the background technology is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of the present invention. Summary of the Invention

[0006] The purpose of this invention is to provide a control method and equipment for a high-acceleration stress test device, so as to solve the technical problem that the valve closing timing is out of sync with the steam saturation state and the test repeatability is poor in the existing HAST equipment due to the use of fixed delay control during the pressure build-up stage.

[0007] To achieve the above objectives, the present invention provides a control method for a high-acceleration stress testing device, including a pressure build-up phase, specifically comprising the following steps: During the heating phase of the test chamber, the exhaust valve should be kept open. Real-time monitoring of exhaust temperature, wherein the exhaust temperature is obtained by a temperature sensor installed on the exhaust passage of the exhaust valve; Determine whether the exhaust temperature has reached the preset trigger temperature, wherein the preset trigger temperature is determined based on the target humidity; When the exhaust temperature reaches the preset trigger temperature, the exhaust valve is closed to allow the test chamber to enter a sealed state and begin to build up test pressure.

[0008] As a further improvement of the present invention, the preset trigger temperature T set Determine by the following formula: T set =T sat (RH) target -ΔT, Wherein: T sat (RH) target ) represents the saturated steam temperature corresponding to the target humidity, and ΔT is the safety margin determined through equipment commissioning tests; The relationship between the target humidity and the saturated steam temperature is pre-stored as a temperature-humidity-saturated pressure relationship table.

[0009] As a further improvement of the present invention, before the exhaust valve is closed, the real-time temperature difference between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity is calculated. When the real-time temperature difference is less than the preset minimum safe temperature difference, the value of the safety margin ΔT is dynamically increased to close the exhaust valve in advance. The minimum safe temperature difference is the lowest temperature difference that can be determined in advance through experiments to prevent condensation in the exhaust channel.

[0010] As a further improvement of the present invention, a steady-state control phase is also included after the pressure is established; The steady-state control phase includes: Multivariable closed-loop decoupled control is implemented for the temperature, humidity, and pressure within the test chamber; among which, The multivariable closed-loop decoupling regulation includes: Based on the detection signals from the dry-bulb temperature sensor and the wet-bulb temperature sensor, an independent first PID control algorithm and a second PID control algorithm are used to independently adjust the output power of the heater and the output power of the steam generator, so as to achieve decoupled regulation of temperature and humidity. Based on the detection signal from the pressure sensor, the third PID control algorithm is used to calculate the pressure regulation amount. According to the positive or negative value of the pressure regulation amount, the opening of the intake regulating valve and the exhaust valve are controlled in a coordinated manner to stabilize the cavity pressure.

[0011] As a further improvement to the present invention, a predictive diagnostic maintenance mechanism is also included: After multiple test cycles, the exhaust temperature-time curves during each pressure build-up phase and the dry-bulb / wet-bulb temperature-time curves during the steady-state control phase were recorded and analyzed. When the slope of the exhaust temperature-time curve shows a trend change that exceeds the preset range, it is determined that the sealing performance of the test chamber has decreased. When the steady-state convergence value of the dry-bulb / wet-bulb temperature-time curve shows a trend change that exceeds the preset range, it is determined that the dry-bulb temperature sensor and / or wet-bulb temperature sensor has drifted. Based on the judgment results, a predictive maintenance alarm signal is generated.

[0012] As a further improvement to the present invention, a condensation risk warning mechanism is also included: The exhaust temperature sensor is reused as a condensation risk monitoring unit during the pressure build-up phase. Before the exhaust valve is closed, the temperature difference between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity is calculated in real time. When the temperature difference is less than the first warning threshold, a condensation risk warning signal is generated, and the exhaust time is extended; When the temperature difference is less than the second warning threshold, the heater is forcibly turned on for preheating until the temperature difference recovers to above the first warning threshold, wherein the second warning threshold is less than the first warning threshold.

[0013] As a further improvement of the present invention, the pressure control method also includes a safety control mechanism: Real-time monitoring of cavity pressure; When abnormal overpressure is detected, the safety handling procedure shall be executed first. The safety handling procedure shall include at least shutting down the heating and humidification system and opening the exhaust valve for emergency pressure relief. The safety control mechanism also includes a mechanical safety valve independent of the controller, which provides dual protection through software safety procedures and a hardware safety valve when the safety procedure fails or the chamber pressure exceeds the mechanically set safety value.

[0014] As a further improvement of the present invention, a sensor fault self-diagnosis mechanism is also included: Before the exhaust valve is closed, the exhaust temperature detected by the exhaust temperature sensor is compared with the dry bulb temperature detected by the dry bulb temperature sensor. When the difference between the two exceeds the preset normal temperature difference range, it is determined that there is a fault in the exhaust temperature sensor or dry bulb temperature sensor, and a fault protection action is executed. The fault protection actions include: closing the exhaust valve using a preset default delay strategy, generating an alarm signal, or switching to a backup sensor; The default delay strategy is as follows: when the dry bulb temperature rises to a preset intermediate value, a fixed delay timer is started, and the exhaust valve is closed after the delay ends.

[0015] To achieve the above objectives, the present invention also provides a high-acceleration stress testing apparatus, comprising: Test chamber; A heating and humidification system is used to heat the test chamber and supply steam to it; Pressure sensor used to monitor cavity pressure; An exhaust valve, connected to the test chamber, is used to control the exhaust of the test chamber; A temperature sensor is installed on the exhaust channel corresponding to the exhaust valve to monitor the exhaust temperature in real time; The controller is electrically connected to the heating and humidification actuator, pressure sensor, temperature sensor, and exhaust valve, and is configured to perform the above control method.

[0016] As a further improvement to the present invention, it also includes: An air intake regulating valve, connected to the test chamber, is used to inflate the test chamber with air; A safety valve is connected to the test chamber. The safety valve is configured to operate independently of the controller and automatically open to release pressure when the pressure in the test chamber exceeds a mechanically set safety value. The controller is further configured to: after the exhaust valve is closed, according to the feedback signal of the pressure sensor, coordinately control the opening of the intake regulating valve and / or the exhaust valve to stabilize the cavity pressure at the target pressure value. The temperature sensor is located upstream of the exhaust channel between the exhaust valve and the test chamber, or downstream of the exhaust valve; when the temperature sensor is located downstream of the exhaust valve, the detected value is corrected by a temperature compensation model.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a control method and apparatus for a high-acceleration stress testing device. By installing a temperature sensor on the exhaust channel to monitor the exhaust temperature in real time, and using the exhaust temperature as a direct indicator of the steam saturation state within the test chamber, it achieves precise judgment of the timing for closing the exhaust valve. The valve is immediately closed when the exhaust temperature reaches a temperature determined based on the target humidity, ensuring that pressure build-up begins under the same steam saturation state in each test. This significantly improves the consistency of test conditions between batches, thereby enhancing the reliability of test data. Furthermore, this invention proposes a preset trigger temperature determined based on the target humidity, enabling the system to automatically adjust the closing timing according to test conditions. This achieves differentiated and precise control for different test modes, expanding the applicability of the equipment.

[0018] On the other hand, by closing the exhaust valve at the optimal time, this invention avoids ineffective steam discharge and unnecessary energy loss. Precise pressure establishment reduces fluctuations and repeated adjustments during subsequent pressure regulation, minimizing redundant actions of the heater, humidification system, and valve actuators, and extending the service life of critical equipment components. Simultaneously, the precise pressure establishment achieved by this invention provides stable initial conditions for subsequent multi-variable closed-loop decoupled control of temperature, humidity, and pressure, making the steady-state control phase smoother and faster, and improving overall control quality. Attached Figure Description

[0019] Figure 1 A schematic diagram of the control system for a high-accelerated stress testing device provided in an embodiment of the present invention.

[0020] Figure 2 The flowchart of the pressure control method for the high accelerated stress testing equipment provided in the embodiment of the present invention specifically illustrates the pressure control method in the pressure build-up stage.

[0021] Figure 3 The test mode and preset trigger temperature linkage control logic diagram provided in the embodiments of the present invention.

[0022] Figure 4 A closed-loop control flowchart of the pressure control method for high-accelerated stress testing equipment provided in an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the temperature and humidity control range provided in an embodiment of the present invention.

[0024] Figure 6 A security control logic diagram provided for embodiments of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0026] To better understand the control logic of this invention, the overall architecture of the control system is first described. The control system of this invention adopts a three-layer architecture (see reference). Figure 1 (The schematic diagram shown indicates the functional units corresponding to each layer.) The first layer—the sensing layer—includes dry-bulb temperature sensors, wet-bulb temperature sensors, pressure sensors, and exhaust temperature sensors, used to collect thermodynamic parameters within the test chamber in real time. The sampling frequency of the sensing layer is set to 50Hz-200Hz. The raw signal is processed by a first-order low-pass filter (filter time constant of 0.1 seconds-1.0 seconds) and then converted into a digital signal by a 12-bit ADC before being sent to the controller.

[0027] The second layer—the decision layer—is the controller. It runs PID control algorithms, multivariable decoupling algorithms, and condensation risk warning algorithms, and calculates control commands based on feedback signals from the sensing layer. The controller has a pre-stored temperature-humidity-saturation pressure relationship table (as shown in Table 1) for quickly querying the wet-bulb temperature corresponding to the target humidity.

[0028] The third layer—the execution layer—includes heaters, steam generators, intake regulating valves, and exhaust valves, which execute corresponding actions based on control commands from the decision layer. The actuator response time is less than 0.1 to 1 second, ensuring the real-time performance of the control system.

[0029] The following is for reference Figure 1 Each functional unit is described in detail. Figure 1 The schematic diagram of the control system of a high-acceleration stress testing device provided in the embodiment of the present invention includes the following core functional units: The test chamber is used to place electronic components, semiconductor packages, polymer materials and other test devices, and provides a high temperature, high humidity and high pressure environment.

[0030] The sensing and detection unit includes a temperature sensing module and a pressure sensing module.

[0031] The temperature sensing module is equipped with a dry-bulb temperature sensor and a wet-bulb temperature sensor. The dry-bulb temperature sensor is used to directly measure the air temperature inside the test chamber. The wet-bulb temperature sensor measures the temperature of a temperature probe wrapped with damp gauze and, in combination with the dry-bulb temperature, the controller calculates the current relative humidity (%RH) inside the test chamber.

[0032] For test chambers with small volumes, a set of dry-bulb and wet-bulb temperature sensors can be installed in the center of the test chamber or at the return air vent. This arrangement is simple in structure and can meet the temperature uniformity requirements of small-volume chambers.

[0033] For applications with larger volumes or higher requirements for temperature and humidity uniformity, multiple sets of dry-bulb and wet-bulb temperature sensors can be installed at different locations within the test chamber (such as the top, middle, and bottom). The average temperature and humidity within the test chamber can be calculated using an arithmetic average or weighted average. The weighting coefficients for the weighted average can be preset according to the importance of the sensor locations. With multiple sensor configurations, the temperature uniformity within the chamber can be improved from ±1.5℃ to ±0.8℃, and the humidity uniformity from ±3%RH to ±1.5%RH.

[0034] In addition, the temperature sensing module also includes an exhaust temperature sensor. This exhaust temperature sensor is located on the exhaust channel communicating with the test chamber, upstream or downstream of the exhaust valve, and is used to monitor the temperature of the gas discharged from the test chamber in real time. This monitoring data serves both system safety protection (such as preventing overheating during exhaust) and as a core trigger parameter for the pressure build-up phase of this invention.

[0035] In a preferred embodiment, the exhaust temperature sensor is positioned on the exhaust channel communicating with the test chamber, and upstream of the exhaust valve (i.e., between the exhaust valve and the test chamber). This arrangement allows for the measurement of the temperature of gas exiting the test chamber but before it has passed through the exhaust valve for cooling, thus more accurately reflecting the steam saturation state within the chamber. When high-temperature, high-humidity gas flows through the exhaust valve, the gas temperature may decrease due to the valve's heat capacity and heat dissipation effect. If the sensor is positioned downstream of the exhaust valve, the measured temperature may be lower than the actual steam temperature within the chamber, leading to a delay in valve closure and increasing the risk of condensation. Therefore, positioning the sensor upstream of the exhaust valve avoids the valve's influence on measurement accuracy, ensuring the accuracy of the monitoring data.

[0036] If the exhaust temperature sensor must be located downstream of the exhaust valve due to equipment structure limitations, a calibration test is needed to establish the correspondence between the downstream and upstream temperatures, and temperature compensation correction should be performed in the control logic. Specifically, temperature sensors can be installed simultaneously upstream and downstream of the exhaust valve. Multiple tests can be conducted to obtain temperature difference values ​​under different operating conditions, establishing a compensation model to infer the actual upstream temperature from the downstream measurement value in the control program.

[0037] In one specific embodiment, the exhaust temperature sensor can be installed at the valve inlet of the exhaust valve, or at a position 5cm-20cm away from the exhaust valve inlet on the exhaust pipe. This position can effectively measure the exhaust temperature while avoiding the impact of airflow disturbances caused by the operation of the exhaust valve on the measurement accuracy.

[0038] The pressure sensing module uses a pressure sensor to directly measure the absolute pressure or gauge pressure inside the test chamber, providing feedback signals for pressure closed-loop control.

[0039] The controller employs a high-performance programmable logic controller (PLC) or a dedicated temperature and humidity programmable controller (CPU) as the core of the control system. The controller receives detection signals from all sensors, runs preset control algorithms (such as PID algorithms), and issues precise control commands to each actuator based on the set temperature, humidity, and pressure programs or setpoints. The controller also manages the human-machine interface, program storage, alarm logic, and data logging.

[0040] The actuator unit directly influences the test environment according to the controller's instructions. The actuator unit includes a heating and humidification actuator system and a pressure control actuator system.

[0041] The heating and humidification system is implemented through two core components: a heater and a steam generator. The heater, typically an electric heating element, heats the air entering the test chamber or the chamber walls to increase the dry-bulb temperature. The steam generator electrically heats deionized water into pure steam, which is then injected into the test chamber through piping to increase the absolute humidity within the chamber. The system receives "hot air / steam" generation commands from the controller.

[0042] The pressure control system regulates the chamber pressure by controlling the gas flow rate. It mainly includes an inlet valve, an exhaust valve, and a safety valve. The inlet valve, connected to the test chamber, injects compressed clean air or nitrogen into the sealed chamber to increase the pressure; it can be configured as a solenoid valve or an electric regulating valve. The exhaust valve, also connected to the test chamber and precisely controlled by the controller, discharges gas from the test chamber as needed to reduce and stabilize the pressure; it can be configured as an electric or pneumatic regulating valve.

[0043] The safety valve of this invention is configured as a mechanical protection device independent of the controller, and its opening pressure setting value is higher than the normal operating pressure range. When the pressure in the test chamber abnormally rises above the safety threshold for any reason (including control system failure), the safety valve will automatically and forcibly open to release pressure, providing the highest level of safety protection. Its action does not depend on the controller's command.

[0044] Meanwhile, after the exhaust valve closes, the controller, based on feedback signals from the pressure sensor, coordinates the opening of the intake regulating valve and / or the exhaust valve to stabilize the chamber pressure at the target pressure value. Specifically, when the pressure is too low, the controller opens or increases the opening of the intake regulating valve to replenish the chamber with air; when the pressure is too high, the controller opens or increases the opening of the exhaust valve to release excess pressure. Through this dual pressure management mechanism of "hardware safety valve + controller coordinated control," this invention ensures both the safety of the experimental process and achieves precise and stable pressure control.

[0045] In the HAST experiment, pressure is the core parameter for simulating a specific saturated water vapor environment and achieving a set relative humidity (RH). According to Dalton's law of partial pressures and the Clausius-Clapeyron equation, in a closed container, when the dry-bulb temperature and the wet-bulb temperature reach a stable difference, the water vapor partial pressure inside the container reaches a saturated or supersaturated state, thus forming the corresponding relative humidity and total pressure.

[0046] The control principle of this invention is as follows: Figure 1 The diagram shows a multivariable (temperature, humidity, pressure), strongly coupled, closed-loop feedback control system. The following section combines... Figures 2 to 6 The control method of the present invention will be described in detail.

[0047] Figure 2 The flowchart of the control method for the high-accelerated stress testing equipment provided in this embodiment of the invention specifically illustrates the control method during the pressure build-up stage. (Refer to...) Figure 2 and combined Figure 1 As shown, the pressure build-up phase includes the following steps: Step S11: During the heating phase of the test chamber, keep the exhaust valve in the open position.

[0048] During the initial heating phase of the HAST experiment, the test chamber is filled with room temperature air. If the exhaust valve is closed at this point, the residual cold air in the chamber will expand upon heating during subsequent heating, causing abnormal pressure fluctuations and interfering with the accuracy of humidity establishment. Simultaneously, the presence of cold air will hinder the uniform distribution of steam, affecting the formation of a saturated environment. Therefore, this step involves keeping the exhaust valve open to ensure that the cold air in the test chamber is promptly discharged during heating, creating pure, humid heat conditions for the subsequent establishment of a steam saturated environment.

[0049] Step S12: Real-time monitoring of exhaust temperature, wherein the exhaust temperature is obtained by a temperature sensor installed on the exhaust passage of the exhaust valve.

[0050] The temperature sensor installed on the exhaust passage of the exhaust valve is called the exhaust temperature sensor. This step uses this sensor to monitor the temperature of the gas discharged from the test chamber in real time. Exhaust temperature is a key indicator reflecting the steam saturation state within the test chamber: when the exhaust temperature is low, it indicates that the chamber is still dominated by cold air, and steam has not yet been fully generated; when the exhaust temperature rises to near the saturation steam temperature, it indicates that a stable steam environment has been formed within the test chamber, and the cold air has been fully replaced. Therefore, the purpose of real-time monitoring of the exhaust temperature is to accurately determine the changing trend of the steam saturation state within the chamber, providing a data basis for subsequent valve closing decisions.

[0051] Step S13: Determine whether the exhaust temperature has reached the preset trigger temperature, wherein the preset trigger temperature is determined based on the target humidity.

[0052] In terms of physical principles, different target humidity levels correspond to different saturated vapor temperatures. Therefore, the preset trigger temperature in this step is not a fixed value, but is dynamically determined based on the target humidity.

[0053] Reference Figure 3 As shown, Figure 3 This is a logic diagram illustrating the test mode and trigger temperature linkage control provided in an embodiment of the present invention. The present invention supports at least two test modes: Saturation Test Mode (STD): In this mode, the controller automatically locks the humidity control target to 100%RH, primarily used for standard testing to compare data with other saturation devices. The preset trigger temperature during the pressure build-up phase corresponds to the saturation state at 100%RH. Unsaturated test mode: In this mode, the humidity control target can be set by the user within the range of 65%RH to 100%RH, mainly used for reliability evaluation tests simulating different humidity conditions. The preset trigger temperature of the pressure build-up phase is dynamically adjusted according to the set humidity target value.

[0054] The critical condition for condensation can be quantified as follows: when the temperature of the exhaust channel is lower than the saturated vapor temperature (i.e., wet-bulb temperature) corresponding to the target humidity, the water vapor in the hot, moist steam will reach a supersaturated state, thus condensing into liquid water on the cold surface. Condensate may backflow into the test chamber, contaminating the sample; it may also accumulate at the valve body, leading to poor valve sealing and failure to build up pressure.

[0055] On the other hand, if the preset trigger temperature is too high (close to or equal to the wet-bulb temperature), the valve will close too late, which may lead to pressure overshoot; if the preset trigger temperature is too low, the valve will close too early, increasing the risk of condensation.

[0056] Therefore, determining the preset trigger temperature requires striking a balance between avoiding pressure overshoot and preventing condensation. In practical engineering, avoiding pressure overshoot is given priority, so the preset trigger temperature is usually set below the wet-bulb temperature to allow for a buffer during pressure buildup.

[0057] Based on the above physical principles, a preset trigger temperature is established. T set Determine by the following formula: T set =T sat (RH) target -ΔT, Wherein: T sat (RH) target ) represents the saturated vapor temperature (i.e., wet-bulb temperature) corresponding to the target humidity, in °C; ΔT is the safety margin, determined through equipment commissioning tests, in °C.

[0058] The principle for determining the safety margin ΔT is to ensure that the pressure rises smoothly to the target value after the valve is closed, without overshoot. A larger value results in earlier valve closure and a lower risk of pressure overshoot, but increases the risk of condensation; a smaller value results in later valve closure and a lower risk of condensation, but increases the risk of pressure overshoot. The optimal value needs to be determined through equipment commissioning tests.

[0059] As one implementation method, a standard test procedure is run, the exhaust temperature value when the pressure begins to rise steadily is observed, the difference between this value and the wet-bulb temperature is calculated, and the optimal safety margin ΔT is obtained by averaging the values ​​from multiple tests. Those skilled in the art can determine the optimal value suitable for specific equipment through a limited number of tests.

[0060] Based on the above method, the preset trigger temperature T set It can be determined in the following ways: The first step is to look up the pre-stored temperature-humidity-saturation pressure correlation table based on the target humidity to obtain the wet-bulb temperature at the corresponding humidity.

[0061] For example, taking the 130℃ dry-bulb temperature commonly used in HAST tests as an example, the wet-bulb temperatures corresponding to different target humidity levels are shown in Table 1: Table 1. Correlation between temperature, humidity, and saturation pressure (dry bulb temperature 130℃)

[0062] The wet-bulb temperatures mentioned above reflect the theoretical temperatures at which steam reaches saturation under different target humidity levels. However, in actual control, the setting of the preset trigger temperature also needs to consider factors such as system response delay and equipment characteristics.

[0063] The second step is to determine the safety margin ΔT through equipment debugging and testing, and to set the wet-bulb temperature T... sat (RH)target Subtracting the safety margin ΔT yields the preset trigger temperature T. set .

[0064] When the exhaust temperature reaches the preset trigger temperature, it indicates that an initial steam environment meeting the target humidity requirements has been formed in the test chamber, and the cold air has been fully discharged.

[0065] As a further improvement of the present invention, the safety margin ΔT is not fixed, but can be dynamically adjusted according to real-time operating conditions. Specifically, before the exhaust valve closes, the controller continuously calculates the real-time temperature difference ΔT between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity. real When ΔT real Less than the preset minimum safe temperature difference ΔT min When this occurs, it indicates that the condensation risk under actual operating conditions is higher than expected. The controller automatically increases the safety margin ΔT by one step, bringing the preset trigger temperature T back up. set The corresponding reduction allows the exhaust valve to be closed earlier, proactively avoiding the risk of condensation.

[0066] Minimum safe temperature difference ΔT min The calibration method for determining the minimum temperature difference that can prevent condensation in the exhaust channel, which is determined in advance through experiments, is as follows: Under standard test conditions, gradually reduce the difference between the exhaust temperature and the saturated steam temperature, observe whether visible condensate droplets appear on the inner wall of the exhaust channel, record the temperature difference value when condensation begins, and add a safety margin to this value as the minimum safe temperature difference.

[0067] In one embodiment, the safety margin ΔT is preferably in the range of 0.5℃-5℃, and the minimum safe temperature difference ΔT min The preferred value range is 0.3℃-1.5℃, and the preferred value range for the safety margin ΔT step size is 0.1℃-0.5℃. The specific values ​​of the above parameters can be determined through equipment debugging and testing optimization. Those skilled in the art can obtain the optimal values ​​applicable to specific equipment through a limited number of tests.

[0068] Through this adaptive adjustment mechanism, the present invention can dynamically optimize the valve closing timing according to the actual operating conditions of different test batches (such as initial humidity, load size, etc.), thereby further improving the robustness and adaptability of the control.

[0069] Step S14: When the exhaust temperature reaches the preset trigger temperature, close the exhaust valve to allow the test chamber to enter a sealed state and begin to build up the test pressure.

[0070] When the exhaust temperature reaches the preset trigger temperature, the exhaust valve is closed, the test chamber becomes sealed, the pressure begins to rise, and the pressure build-up phase begins.

[0071] To prevent false triggering due to brief fluctuations in exhaust temperature, a stability assessment step may be included between steps S13 and S14: Step S13A: After the exhaust temperature reaches the preset trigger temperature, determine whether the temperature remains stable for a preset duration. This preset duration can be set according to the system response characteristics, preferably 5 to 30 seconds. Step S14 is executed only if the exhaust temperature remains stable above the preset trigger temperature threshold within the preset duration; otherwise, return to step S12 to continue monitoring.

[0072] Through the above steps, the present invention immediately closes the valve when the exhaust temperature reaches the temperature value determined based on the target humidity, ensuring that the pressure build-up is initiated under the same steam saturation state in each test, which significantly improves the consistency of test conditions between batches.

[0073] Reference Figure 4 As shown, Figure 4 This is a closed-loop control flowchart of a pressure control method for a high-accelerated stress testing device provided in an embodiment of the present invention. The control method includes a pressure build-up stage, a steady-state control stage, and a feedback closed-loop stage. Step S10: Pressure build-up stage.

[0074] This stage employs the pressure control methods described in the pressure establishment stage, specifically including: S11, during the heating stage, the exhaust valve is opened.

[0075] S12 monitors exhaust temperature.

[0076] S13, determine whether the exhaust temperature has reached the preset trigger temperature determined based on the target humidity.

[0077] As a preferred embodiment, it also includes step S13A, which is to determine whether the temperature remains stable for a preset duration (e.g., 5 seconds to 30 seconds) after the exhaust temperature reaches the preset trigger temperature. If it is stable, continue; otherwise, return to S12.

[0078] S14: When the preset trigger temperature is reached, close the exhaust valve and begin to build up the test pressure.

[0079] It should be noted that the pressure build-up phase and the steady-state control phase are sequential. Once the exhaust valve is closed and the test chamber begins to build pressure, the system automatically enters the steady-state control phase. In other words, the steady-state control phase starts simultaneously with the completion of the pressure build-up phase, with a seamless transition between the two phases. During the steady-state control phase, the controller continuously performs coordinated pressure control to ensure that the chamber pressure remains stable at the target pressure value.

[0080] Step S20: Steady-state control stage.

[0081] After pressure is established, the exhaust valve remains closed, and the test chamber is in a sealed state. Entering the steady-state control phase, a multivariable closed-loop decoupled control method is employed to coordinately regulate the temperature, humidity, and pressure within the test chamber. Specifically, the following steps are included: S21 collects dry-bulb temperature, wet-bulb temperature, and pressure.

[0082] The system collects signals from the dry-bulb temperature sensor, wet-bulb temperature sensor, and pressure sensor to obtain the current temperature T. current RH humidity current and pressure P current .

[0083] S22, compare with the set value and calculate the deviation.

[0084] Compare the collected values ​​with the user-defined target temperature T. target Target humidity RH target Target pressure P target Compare and calculate the deviation: e T =T target -T current , e RH =RH target -RH current , e p =P target -P current .

[0085] S23, PID control algorithm.

[0086] Independent PID control algorithms are used to calculate the control quantities for temperature, humidity, and pressure separately.

[0087] Temperature control: Employs the first PID control algorithm, based on the temperature deviation e. T The cumulative deviation and the rate of change of the deviation, and the control quantity U of the output heater. T .

[0088] Humidity control: Employs a second PID control algorithm, based on the humidity deviation e. RH The cumulative deviation and the rate of change of the deviation, and the control quantity U of the output steam generator. RH .

[0089] Pressure control: A third PID control algorithm is used, based on the pressure deviation e. p The cumulative deviation and the rate of change of the deviation, and the output pressure regulation U. P .

[0090] In one implementation, the proportional coefficient Kp of the first, second, and third PID control algorithms is preferably in the range of 0.5-5, the integral time Ti is preferably in the range of 10-120 seconds, and the derivative time Td is preferably in the range of 0-30 seconds. Through optimized combination of these parameters, the pressure control accuracy can reach ±0.005 MPa.

[0091] S24, temperature regulation.

[0092] According to the temperature control quantity U T Independently control the heater to regulate temperature: when e T When e > 0 (i.e., the temperature is too low), increase the heater output power; when e T When the temperature is <0 (i.e., the temperature is too high), reduce the output power of the heater.

[0093] S25, humidity control.

[0094] According to humidity control amount U RH Independent control of the steam generator to regulate humidity: when e RH When e > 0 (i.e., humidity is low), increase the output power of the steam generator; when e RH When the humidity is <0 (i.e., the humidity is too high), reduce the output power of the steam generator.

[0095] S26, Pressure Regulation.

[0096] According to the pressure adjustment amount U P The positive and negative values ​​of U are used to coordinate the control of the intake valve and the pressure relief valve to regulate the pressure: when U P When the pressure is >0 (i.e., low), open or increase the intake valve opening to replenish air into the cavity; when U P When U < 0 (i.e., pressure is too high), open or increase the opening of the pressure relief valve to release excess pressure; when U P When =0, the current valve opening remains unchanged.

[0097] By employing independent PID control algorithms to adjust temperature and humidity separately, this invention achieves decoupled control of temperature and humidity, avoiding mutual interference during the temperature and humidity regulation process. Simultaneously, by coordinating the control of the intake valve and pressure relief valve based on the positive and negative values ​​of the pressure regulation, precise and stable pressure regulation is achieved.

[0098] In another implementation, the controller uses a fuzzy PID control algorithm instead of the standard PID algorithm. The fuzzy PID controller takes the deviation e and the rate of change of deviation ec as inputs and dynamically adjusts the PID parameters (Kp, Ki, Kd) according to fuzzy rules to adapt to control requirements under different load conditions. After adopting the fuzzy PID algorithm, the temperature overshoot can be reduced from 5% of the standard PID to 2%, and the settling time is shortened by approximately 30%.

[0099] Reference Figure 5 As shown, Figure 5 This diagram illustrates the temperature and humidity control range provided in this embodiment of the invention. The diagram shows the dry-bulb temperature range (from the lowest test temperature to the highest test temperature) that can be maintained during the steady-state control phase. For example, when the target humidity is 100%RH, the corresponding dry-bulb temperature control range is approximately 105℃-134℃; when the target humidity is 85%RH, the corresponding dry-bulb temperature control range is approximately 110℃-140℃; and when the target humidity is 75%RH, the corresponding dry-bulb temperature control range is approximately 114℃-144℃. This diagram illustrates the different steady-state operating temperature ranges corresponding to different target humidity levels, and users can refer to this diagram when setting target test conditions.

[0100] The implementation of the above-mentioned PID control algorithm relies on accurate signal acquisition and processing. In one embodiment, the signal processing flow of the present invention is as follows: Step 1) Data Acquisition: Acquire dry-bulb temperature, wet-bulb temperature, pressure, and exhaust temperature signals at a sampling frequency of 50Hz-200Hz. This sampling frequency selection balances real-time control with signal noise suppression and is sufficient to capture dynamic changes in thermodynamic parameters.

[0101] Step 2) Filtering: The original signal is processed using a first-order low-pass filter with a filtering time constant of 0.1 seconds to 1.0 seconds (e.g., 0.5 seconds) to eliminate high-frequency noise and transient interference.

[0102] Step 3) Conversion: The filtered analog signal is converted into a digital signal through a 12-bit ADC with a temperature resolution of 0.1℃ and a pressure resolution of 0.001MPa.

[0103] Step 4) Calculation: The controller calculates the temperature deviation e based on the digital signal. T Humidity deviation e RH Pressure deviation e p It then calls the PID control algorithm to calculate the control quantity.

[0104] Step 5) Output: The 12-bit DAC outputs a 0-10V analog signal to control the power of the heater and steam generator, and the PWM output (frequency 1kHz, duty cycle 0%-100%) controls the opening of the solenoid valve.

[0105] Step S30: Feedback closed-loop stage.

[0106] The actuator's actions change the temperature, humidity, and pressure conditions inside the test chamber. The changed conditions are detected in real time by the sensors and transmitted back to step S20 as new feedback signals, forming a closed-loop control.

[0107] Through the closed-loop control steps of the pressure control method described above, this invention achieves coordinated control of temperature, humidity and pressure within the test chamber, ensuring the stability and consistency of test conditions, and effectively improving control accuracy and test repeatability.

[0108] The high-accelerated stress testing equipment provided by this invention also supports three venting modes for users to choose from, in order to meet the requirements of different standards for sample protection: Mode 1: Slow cooling mode at set humidity. In this mode, after the test, the chamber temperature is gradually cooled while maintaining the set humidity condition until it drops to 100°C. This mode effectively protects the sample from pressure stress and drying damage.

[0109] Mode 2: Motion Cooling Mode. In this mode, the chamber pressure is not immediately vented after the test. Cooling only begins after the chamber pressure drops to 0 MPa. Forced cooling is achieved in a short time by an external cooling fan, which avoids causing rapid temperature changes and pressure stress on the sample.

[0110] Mode 3: Rapid Exhaust Mode. In this mode, the exhaust valve opens immediately after the test to expel hot gas and air in a short time, making it suitable for scenarios with high test efficiency requirements.

[0111] Reference Figure 6 As shown, Figure 6 A security control logic diagram provided for embodiments of the present invention.

[0112] The safety devices in this invention include, but are not limited to: safety pressure valve, overpressure device, overheat prevention device, low water level cut-off device, heater circuit breaker, thermal fuse, door lock safety device, grounding leakage circuit breaker, and isolation and pressure protection device.

[0113] The present invention also includes the following safety control steps: Step S41, real-time monitoring.

[0114] The controller monitors the exhaust temperature, chamber pressure, water level in the water tank, and the status of the emergency stop switch in real time.

[0115] Step S42, software security assessment.

[0116] Determine if any of the following abnormal conditions exist: exhaust temperature exceeds the safety threshold, chamber pressure exceeds the software safety threshold, water level in the water tank is below the low water level threshold, or the emergency stop switch is pressed.

[0117] Step S43, software security measures.

[0118] When any abnormal situation occurs, the controller immediately interrupts the normal control logic and prioritizes the execution of the safety handling procedure. This safety handling procedure includes at least: shutting down the heater, shutting down the humidification system, opening the exhaust valve for emergency pressure relief, automatically performing pressure reduction and exhaust operations, recording alarm information, and displaying the fault monitor screen.

[0119] Step S44, hardware security check.

[0120] Meanwhile, a mechanical safety valve, independent of the controller, continuously monitors the chamber pressure. When the chamber pressure exceeds the mechanically set safety value, the safety valve will automatically open.

[0121] Step S45, hardware safety depressurization.

[0122] The safety valve operates independently, forcibly opening to relieve pressure, without relying on controller commands.

[0123] By coordinating software security measures (steps S41-S43) and hardware safety valves (steps S44-S45), this invention forms a dual protection mechanism of software security measures and hardware safety valves, ensuring automatic pressure relief even in extreme situations such as control system failures, thus guaranteeing the safety of equipment and personnel. When the door is opened during operation, the door lock safety device is automatically triggered, causing the equipment to stop working or triggering an alarm.

[0124] This invention also provides a condensation risk early warning mechanism to proactively identify and avoid condensation risks during the pressure build-up phase. Specifically, before the exhaust valve closes, the controller calculates in real time the temperature difference ΔT between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity. real and the preset first warning threshold T warn1 Second warning threshold T warn2 Comparison, where T warn2 < T warn1 .

[0125] When ΔT real < T warn1 When this happens, the controller generates a condensation risk warning signal to alert the operator and automatically extends the exhaust time to allow the exhaust channel to be fully preheated, thereby reducing the risk of condensation.

[0126] When ΔT real < T warn2 When the temperature reaches a certain level, indicating a high risk of condensation, the controller forcibly activates the heater for preheating until ΔT is reached. real Restore to T warn1 After ensuring the exhaust channel temperature reaches a safe level, the exhaust valve is closed. Through this tiered early warning and proactive intervention mechanism, this invention can intervene before condensation occurs, effectively preventing condensate backflow and equipment damage.

[0127] In one embodiment, the first warning threshold is preferably in the range of 1℃-3℃, and the second warning threshold is preferably in the range of 0.3℃-1℃.

[0128] The exhaust temperature sensor in this invention is given multiple functions during the pressure build-up phase: (1) Valve closing timing judgment. The detection value of the exhaust temperature sensor is the core trigger condition for judging when the exhaust valve closes. When the exhaust temperature reaches the preset trigger temperature determined based on the target humidity, the controller closes the exhaust valve, so that the test chamber enters a sealed state and begins to build up the test pressure.

[0129] (2) Condensation risk warning. Before the exhaust valve is closed, the controller uses the exhaust temperature to provide a condensation risk warning: calculate the temperature difference between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity in real time. When the temperature difference is less than the warning threshold, execute active protection procedures such as extending the exhaust and forced preheating to avoid the condensation risk.

[0130] (3) Over-temperature protection. During the pressure build-up phase, the exhaust temperature sensor readings also serve as one of the criteria for over-temperature protection. When the exhaust temperature exceeds the safety threshold, the controller executes a safety procedure.

[0131] Through this multi-functional reuse design, the present invention fully explores the detection value of the exhaust temperature sensor, realizes the intelligent application of exhaust temperature, and improves the system's functional integration and control reliability.

[0132] This invention also provides a predictive diagnostic maintenance mechanism for assessing the health status of equipment after multiple test cycles. Specifically, the controller records and analyzes the exhaust temperature-time curve for each pressure build-up phase, and the dry-bulb / wet-bulb temperature-time curve for the steady-state control phase; When the slope of the exhaust temperature-time curve shows a trend change that exceeds the preset range (for example, a gradually decreasing slope indicates an increase in exhaust channel resistance), it is determined that the sealing performance of the test chamber has decreased. When the steady-state convergence value of the dry-bulb / wet-bulb temperature-time curve shows a trend change that exceeds the preset range (for example, the steady-state temperature deviates from the set value), it is determined that the dry-bulb temperature sensor and / or wet-bulb temperature sensor has drifted. Based on the judgment results, a predictive maintenance alarm signal is generated.

[0133] Through this predictive diagnostic maintenance mechanism, the present invention can provide early warnings before equipment failures occur, enabling a shift from fault repair to proactive maintenance, reducing equipment downtime, and extending equipment lifespan.

[0134] This invention also provides a sensor fault self-diagnosis mechanism for identifying sensor faults during the pressure build-up phase. Specifically, before the exhaust valve closes, the controller compares the exhaust temperature detected by the exhaust temperature sensor with the dry-bulb temperature detected by the dry-bulb temperature sensor.

[0135] Under normal operating conditions, the exhaust temperature is higher than the dry-bulb temperature (because the exhaust is heated, humid gas). When the difference between the two exceeds the preset normal temperature difference range, it is determined that the exhaust temperature sensor or the dry-bulb temperature sensor is faulty, and fault protection actions are executed.

[0136] Fault protection actions include: closing the exhaust valve using a preset default delay strategy, generating an alarm signal, or switching to a backup sensor. The default delay strategy is as follows: when the dry-bulb temperature rises to a preset intermediate value, a fixed delay timer is started, and the exhaust valve is closed after the delay. This default delay strategy serves as a fallback mechanism in case of sensor failure, ensuring the safe termination of the test.

[0137] Through this sensor fault self-diagnosis mechanism, the present invention can detect sensor faults in a timely manner and take corresponding protective measures to avoid control failure or malfunction due to sensor faults, thereby further improving the reliability and safety of the system.

[0138] To verify the technical effectiveness of this invention, a comparative experiment was conducted between the method of this invention and an existing fixed-delay control method. The test conditions were: target temperature 130℃, target humidity 85%RH, and target pressure 0.2MPa.

[0139] Experimental results show that: Using the existing fixed-delay control method, the average time for the pressure build-up phase is about 12 minutes, and the standard deviation of pressure build-up time between batches is relatively large.

[0140] Using the control method provided by this invention, the average time for the pressure build-up phase is about 8 minutes, and the standard deviation of pressure build-up time between batches is reduced by about 65%.

[0141] Furthermore, after 100 hours of continuous operation, an inspection of the exhaust channel revealed no condensate backflow in the equipment using the control method of this invention, while the equipment using the existing method showed slight condensation marks. In a 1000-hour continuous operation test, the equipment using the method of this invention did not exhibit any deviations in test conditions due to inconsistent pressure build-up, while the equipment using the existing method showed significant pressure build-up curve drift after 500 hours of operation.

[0142] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

[0143] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A control method for a high-acceleration stress testing device, characterized in that, This includes the stress build-up phase, which specifically comprises the following steps: During the heating phase of the test chamber, the exhaust valve should be kept open. Real-time monitoring of exhaust temperature, wherein the exhaust temperature is obtained by a temperature sensor installed on the exhaust passage of the exhaust valve; Determine whether the exhaust temperature has reached a preset trigger temperature, wherein the preset trigger temperature is determined based on the target humidity; the preset trigger temperature T set Determine by the following formula: T set =T sat (RH target )-ΔT Wherein: T sat (RH) target ) represents the saturated steam temperature corresponding to the target humidity, and ΔT is the safety margin determined through equipment commissioning tests; The relationship between the target humidity and the saturated steam temperature is pre-stored as a temperature-humidity-saturated pressure relationship table; Before the exhaust valve is closed, calculate the real-time temperature difference between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity. When the real-time temperature difference is less than the preset minimum safe temperature difference, the value of the safety margin ΔT is dynamically increased to close the exhaust valve in advance. The minimum safe temperature difference is the lowest temperature difference that can be determined in advance through testing to prevent condensation in the exhaust channel; When the exhaust temperature reaches the preset trigger temperature, the exhaust valve is closed to allow the test chamber to enter a sealed state and begin to build up test pressure.

2. The control method according to claim 1, characterized in that, After the pressure is established, there is also a steady-state control phase; The steady-state control phase includes: The temperature, humidity, and pressure within the test chamber are controlled using a multivariable closed-loop decoupled system; wherein, The multivariable closed-loop decoupling control includes: Based on the detection signals from the dry-bulb temperature sensor and the wet-bulb temperature sensor, an independent first PID control algorithm and a second PID control algorithm are used to independently adjust the output power of the heater and the output power of the steam generator, so as to achieve decoupled regulation of temperature and humidity. Based on the detection signal from the pressure sensor, the third PID control algorithm is used to calculate the pressure regulation amount. According to the positive or negative value of the pressure regulation amount, the opening of the intake regulating valve and the exhaust valve are controlled in a coordinated manner to stabilize the cavity pressure.

3. The control method according to claim 2, characterized in that, It also includes predictive diagnostic maintenance mechanisms: After multiple test cycles, the exhaust temperature-time curves during each pressure build-up phase and the dry-bulb / wet-bulb temperature-time curves during the steady-state control phase were recorded and analyzed. When the slope of the exhaust temperature-time curve shows a trend change that exceeds the preset range, it is determined that the sealing performance of the test chamber has decreased. When the steady-state convergence value of the dry-bulb / wet-bulb temperature-time curve shows a trend change that exceeds the preset range, it is determined that the dry-bulb temperature sensor and / or wet-bulb temperature sensor has drifted. Based on the judgment results, a predictive maintenance alarm signal is generated.

4. The control method according to claim 1, characterized in that, It also includes a condensation risk early warning mechanism: The exhaust temperature sensor is reused as a condensation risk monitoring unit during the pressure build-up phase. Before the exhaust valve is closed, the temperature difference between the current exhaust temperature and the saturated steam temperature corresponding to the current target humidity is calculated in real time. When the temperature difference is less than the first warning threshold, a condensation risk warning signal is generated, and the exhaust time is extended; When the temperature difference is less than the second warning threshold, the heater is forcibly turned on for preheating until the temperature difference recovers to above the first warning threshold, wherein the second warning threshold is less than the first warning threshold.

5. The control method according to claim 1, characterized in that, It also includes security control mechanisms: Real-time monitoring of cavity pressure; When abnormal overpressure is detected, the safety handling procedure shall be executed first. The safety handling procedure shall include at least shutting down the heating and humidification system and opening the exhaust valve for emergency pressure relief. The safety control mechanism is also equipped with a mechanical safety valve independent of the controller, which is used to automatically open and release pressure when the safety procedure fails or the cavity pressure exceeds the mechanically set safety value.

6. The control method according to claim 1, characterized in that, It also includes a sensor fault self-diagnosis mechanism: Before the exhaust valve is closed, the exhaust temperature detected by the exhaust temperature sensor is compared with the dry bulb temperature detected by the dry bulb temperature sensor. When the difference between the two exceeds the preset normal temperature difference range, it is determined that there is a fault in the exhaust temperature sensor or dry bulb temperature sensor, and a fault protection action is executed. The fault protection actions include: closing the exhaust valve using a preset default delay strategy, generating an alarm signal, or switching to a backup sensor; The default delay strategy is as follows: when the dry bulb temperature rises to a preset intermediate value, a fixed delay timer is started, and the exhaust valve is closed after the delay ends.

7. A high-acceleration stress testing device, comprising: Test chamber; A heating and humidification system is used to heat the test chamber and supply steam to it; Pressure sensor used to monitor cavity pressure; An exhaust valve, connected to the test chamber, is used to control the exhaust of the test chamber; A temperature sensor is installed on the exhaust channel corresponding to the exhaust valve to monitor the exhaust temperature in real time; The controller is electrically connected to the heating and humidification actuator, the pressure sensor, the temperature sensor, and the exhaust valve, and is configured to perform the control method as described in any one of claims 1-6.

8. The device according to claim 7, characterized in that, Also includes: An air intake regulating valve, connected to the test chamber, is used to inflate the test chamber with air; A safety valve is connected to the test chamber. The safety valve is configured to be independent of the controller and automatically open to release pressure when the pressure in the chamber exceeds a mechanically set safety value. The controller is further configured to: after the exhaust valve is closed, according to the feedback signal of the pressure sensor, coordinately control the opening of the intake regulating valve and / or the exhaust valve so that the cavity pressure is stabilized at the target pressure value; The temperature sensor is located upstream of the exhaust channel between the exhaust valve and the test chamber, or downstream of the exhaust valve. When the temperature sensor is located downstream of the exhaust valve, the detected value is corrected using a temperature compensation model.

Images