Method and apparatus for detecting leaks based on gas sensor

Abstract

The invention provides a method and equipment for detecting leakage based on a gas sensor, the method and equipment are used for a liquid or gas leakage detection device, and the leakage detection device comprises a vacuumizing device, a sealed low-pressure cavity and the gas sensor; the vacuumizing device is arranged outside the low-pressure cavity, communicates with the low-pressure cavity and is used for regulating and controlling the vacuum degree of the low-pressure cavity; the gas sensor is arranged in the low-pressure cavity; the method comprises the following steps: controlling a to-be-detected element in a low-pressure cavity to meet a detection condition; detecting a component leakage gas concentration change signal in the low-pressure cavity through a gas sensor; and based on the gas concentration change signal, determining whether the leakage rate of the to-be-detected element reaches the standard or not. According to the gas sensor, a low-pressure environment is generated through the vacuumizing device and the low-pressure cavity, competitive adsorption of gas molecules in a normal-pressure environment and gas molecules volatilized by the element to be detected on the surface of the sensor is reduced, the detection sensitivity of the gas sensor is improved, the detection limit is reduced, and the accuracy of leakage detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of leakage detection, and in particular to a method and device for detecting leakage based on a gas sensor. Background Art

[0002] In the production process of new energy vehicles, energy storage equipment, power batteries, medical care, environmental protection and other industries, many components, parts or complete products have strict requirements on sealing performance. The sealing performance of the product is directly related to its performance, service life and safety, and is one of the important technical indicators for measuring product reliability. Leak detection, as a key link to ensure product sealing performance, runs through the entire process of product design, manufacturing, process control, component performance verification and use. Taking new energy batteries as an example, the leakage of electrolyte will affect battery performance and shorten service life at the least, and may even cause catastrophic accidents such as short circuit, fire and even explosion. Therefore, the detection of electrolyte leakage is very important. In the production process, the leakage rate detection standard of the electrolyte is usually set at an extremely low 10 -8 Pa·m 3 / s level, therefore, fast and accurate detection of low leakage rate liquid leakage is crucial to the high-quality and rapid production of these products.

[0003] At present, the detection of low-leakage rate liquid leakage mainly relies on the helium mass spectrometry leak detection method, which requires pressurized helium immersion, static dehelium treatment, and then the mass spectrometer is used to detect the leakage rate of the tracer gas helium molecules to reflect the leakage rate of the liquid to be detected. On the new energy battery production line, the pressurized helium immersion process in the detection of electrolyte leakage usually takes 1 hour. At the same time, the helium mass spectrometer is expensive, resulting in the problems of low efficiency and high cost in this detection process. In recent years, hydrogen leak detection technology has also begun to develop to reduce the cost of leak rate detection. Unlike the helium mass spectrometry leak detection method, hydrogen leak detection technology uses hydrogen molecules as tracer gas, detects hydrogen molecules through hydrogen sensors, and then reflects the leakage rate of the liquid to be detected. However, the existing hydrogen sensors still have problems in selectivity. In addition to hydrogen as a tracer gas, they will also react to alcohol, paint, silicon-containing adhesives, rubber, putty, etc. that are widely present in the field environment, affecting the accuracy and efficiency of detection.

[0004] Gas sensors interact with target gases through gas-sensitive materials to generate light, electricity and other signal changes, thereby achieving gas concentration calibration. Among them, semiconductor resistance, electrochemical, catalytic combustion and other gas sensors have the advantages of simple system, low cost and high efficiency. If the concentration of volatile substances in the liquid to be tested can be accurately detected, the tracer gas molecules can be omitted, that is, the helium or hydrogen immersion process in the helium leak detection or hydrogen leak detection method can be omitted, and in-situ real-time and high-efficiency product leak detection can be achieved. Given that the product standard leak rate is usually at an extremely low 10 -8Pa·m3 / s level. According to the working principle of leak detection and gas movement calculation and analysis, in a test container with a diameter of 200mm and a height of 200mm, the gas accumulates in the atmosphere for 1 hour, and its gas concentration is only about 56ppb. The existing gas sensors are designed to detect gases with concentrations at the ppm level, which is difficult to adapt to the detection needs in low-concentration environments. Therefore, reducing the detection limit of the gas sensor so that it can directly detect liquid or gas molecules leaking at the ppb level, and at the same time, the sensor needs to overcome the interference of other molecules in the environment to achieve accurate detection of low leakage rates. This is a key issue that needs to be urgently addressed in the current low-leakage rate liquid leakage detection technology. Summary of the invention

[0005] The main purpose of the present invention is to provide a method and device for detecting leakage based on a gas sensor, aiming to overcome the problems that the current detection of low leakage rate liquid or gas leakage is easily affected by environmental interference, has low sensitivity, and has a high detection limit.

[0006] To achieve the above-mentioned object, the present invention provides a method for detecting leakage based on a gas sensor, which is used in a leakage detection device, wherein the leakage detection device comprises a vacuum pumping device, a sealed low-pressure cavity and a gas sensor; the vacuum pumping device is arranged outside the low-pressure cavity and is connected to the low-pressure cavity, and is used to adjust the vacuum degree of the low-pressure cavity; the gas sensor is arranged in the low-pressure cavity, and is used to detect the concentration of gas volatilized into the low-pressure cavity due to the leakage of a component to be tested in the low-pressure cavity;

[0007] The method comprises:

[0008] Controlling the element to be tested in the low-pressure cavity to meet the testing conditions;

[0009] Detecting a gas concentration change signal in the low-pressure cavity by the gas sensor;

[0010] Based on the gas concentration change signal, determine whether the leakage rate of the component to be tested meets the standard.

[0011] Further, controlling the element to be tested in the low-pressure cavity to meet the testing conditions includes:

[0012] Based on the vacuum pumping device, adjusting the air pressure in the low-pressure chamber to a predetermined low-pressure state;

[0013] The low-pressure cavity is kept in a closed state, and the element to be tested continues to leak in the low-pressure cavity for a preset time.

[0014] Furthermore, the predetermined low-pressure state is determined by the type of the element to be tested, the detection requirements, the molecular structure of the liquid or gas in the element to be tested, and the linear response range of the gas sensor.

[0015] Further, determining whether the leakage rate of the component under test meets the standard based on the gas concentration change signal includes:

[0016] Transmitting the gas concentration change signal to a data acquisition device;

[0017] Processing the gas concentration change signal based on the data collector to obtain real-time gas concentration;

[0018] Based on the data acquisition device, the leakage rate of the component to be tested is calculated according to the gas concentration, the volume of the low-pressure cavity and the internal gas pressure of the low-pressure cavity;

[0019] Determining whether the leakage rate is less than a threshold value;

[0020] If it is less than, it is determined that the leakage rate of the component to be tested meets the standard.

[0021] Further, after determining whether the leakage rate is less than a threshold, the method further includes:

[0022] If it is not less than, a warning is issued and it is determined whether it is the first leak rate detection;

[0023] If yes, re-entering the step of controlling the component to be tested in the low-pressure cavity to meet the test condition for re-testing;

[0024] If not, it is determined that the leakage rate of the component under test does not meet the standard and is scrapped.

[0025] Furthermore, the calculation formula of the leakage rate is:

[0026]

[0027] Furthermore, the gas sensor includes a semiconductor resistance gas sensor, an electrochemical gas sensor, a catalytic combustion gas sensor, an optical gas sensor, a magnetic gas analysis sensor or a surface acoustic wave gas sensor.

[0028] Furthermore, the component to be tested includes a new energy battery.

[0029] Furthermore, the low-pressure cavity is a sealed cavity with a pressure lower than the atmospheric pressure.

[0030] The present invention also provides a device for detecting leakage based on a gas sensor, wherein the device is used to execute any of the methods described above.

[0031] The method and device for detecting leakage based on a gas sensor provided by the present invention are used in a leakage detection device, wherein the leakage detection device includes: a vacuum pumping device, a sealed low-pressure cavity and a gas sensor; the vacuum pumping device is arranged outside the low-pressure cavity and is connected to the low-pressure cavity, and is used to adjust the vacuum degree of the low-pressure cavity; the gas sensor is arranged in the low-pressure cavity, and is used to detect the concentration of gas generated by the leakage and volatilization of the component to be tested in the low-pressure cavity; the method includes: controlling the component to be tested in the low-pressure cavity to meet the detection conditions; detecting the gas concentration change signal in the low-pressure cavity by the gas sensor; and determining whether the leakage rate of the component to be tested meets the standard based on the gas concentration change signal. In the present invention, a low-pressure environment is generated by a vacuum pumping device and a low-pressure cavity, so as to reduce the competitive adsorption of gas molecules in a normal pressure environment and gas molecules volatilized by the component to be tested on the sensor surface. Compared with the normal pressure detection method, since the relative concentration of molecules in the environment that compete with the molecules to be detected for adsorption is reduced, the detection signal of the sensor has an amplification effect on the gas concentration, thereby indirectly improving the detection sensitivity of the gas sensor and reducing the detection limit; in the low-pressure cavity, the molecules in the cavity environment are clear, which can effectively avoid the interference of uncertain molecules in the traditional normal pressure detection environment, which is beneficial to improve the accuracy of detecting whether the leakage rate of the component to be tested meets the standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of a leakage detection device in one embodiment of the present invention;

[0033] Figure 2 is another structural schematic diagram of a leakage detection device in one embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of the steps of a method for detecting leakage based on a gas sensor in one embodiment of the present invention;

[0035] Figure 4 It is a flow chart of a method for detecting leakage based on a gas sensor in one embodiment of the present invention.

[0036] The implementation, functional features and advantages of the present invention will be further described in conjunction with embodiments and with reference to the accompanying drawings.

[0037] 1. Vacuum pump; 2. Air valve; 3. Component to be tested; 4. Vacuum dial; 5. Gas sensor; 6. Low-pressure chamber; 7. Data collector; 8. Data feedback system. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] Reference Figure 1 as well as Figure 2 , in one embodiment of the present invention, there is provided a leakage detection device, including a vacuum pumping device, a sealed low-pressure chamber 6 and a gas sensor 5;

[0040] The vacuum device is arranged outside the low-pressure cavity 6 and communicated with the low-pressure cavity 6, and is used to adjust the vacuum degree of the low-pressure cavity 6;

[0041] The gas sensor 5 is disposed in the low-pressure cavity 6 and is used to sense the concentration of gas generated by the leakage and volatilization of the component to be tested 3 in the low-pressure cavity 6 .

[0042] In this embodiment, the low-pressure cavity 6 is used to place the component to be tested (such as a new energy battery) in a low-pressure environment to ensure that the pressure of the external environment of the component to be tested is controllable; the low-pressure cavity 6 provides a relatively closed low-pressure space for the component to be tested, ensuring that the external environmental gas will not interfere with the detection process, and the cavity itself does not allow gas leakage, so as to accurately control and maintain the low-pressure environment.

[0043] The gas sensor 5 is installed inside the low-pressure cavity 6 and is used to detect volatile molecules generated by liquid or gas in the component to be detected. The gas sensor 5 can be a semiconductor resistance gas sensor 5, an electrochemical gas sensor 5 or a catalytic combustion gas sensor 5;

[0044] The vacuum device is connected to the low-pressure chamber 6 and is used to reduce the air pressure in the chamber to a desired level, and can achieve different levels of low-pressure states. For different characteristics of the liquid or gas molecules to be detected, the air pressure in the low-pressure chamber 6 can be adjusted to optimize the leak detection effect. When the pressure inside the low-pressure chamber 6 reaches a preset level (e.g., 10 -9 -10 5 Pa), and keep the component to be tested leaking in this environment.

[0045] In this embodiment, the gas concentration amplification effect in a low-pressure environment greatly improves the detection sensitivity of the sensor. Under low-pressure conditions, the number of molecules that compete with the gas to be detected for adsorption per unit volume decreases, and relatively speaking, the proportion of leaked gas molecules increases significantly. The increase in relative concentration allows even a trace amount of liquid to be detected to leak out in a low-pressure environment to produce a sufficiently high relative gas concentration, thereby enhancing the detection capability of the gas sensor 5. This is equivalent to achieving amplification of the gas concentration through a low-pressure environment, allowing the gas sensor 5 to operate at a lower gas concentration, thereby indirectly improving the detection sensitivity of the gas sensor 5 and reducing the detection limit. In a low-pressure environment, the liquid or gas molecules to be detected are more volatile, which helps to achieve an accurately detectable concentration of gas molecules in a relatively short period of time. When detecting in a low-pressure environment, since the molecules in the environment are clear, the influence of uncertain molecules on the gas sensor 5 in a traditional normal-pressure environment can be effectively avoided. Using the gas sensor 5 to perform 10 in a low-pressure environment -8 Pa·m 3 / s level element liquid or gas leakage detection, replacing the traditional helium mass spectrometry and hydrogen leak detection methods, has the advantages of simple preparation process and low cost, and is easy to industrial application.

[0046] In one embodiment, the leakage detection device further includes a data collector 7, which is disposed outside the low-pressure chamber 6 and connected to the gas sensor 5. The data collector 7 can be used to obtain the collected data of the gas sensor 5 for subsequent analysis.

[0047] In this embodiment, the data collector 7 is mainly used to record, process and analyze the detection data of the gas sensor 5. The data collector 7 is connected to the gas sensor 5 inside the low-pressure cavity 6. The data collector 7 is miniaturized and portable, and can accurately capture the dynamic changes in gas concentration when the liquid to be tested leaks, and present a visual curve on the display screen. On this hardware basis, the leakage rate of the component to be tested 3 can be finally determined by the volume and leakage time of the low-pressure cavity 6. By reasonably setting the threshold of the component, a signal alarm is given to the component whose leakage rate does not meet the standard, and a re-inspection is carried out. If the re-inspection fails to meet the standard again, the leak detection product can be scrapped.

[0048] In one embodiment, the leakage detection device further includes a data feedback system 8 (e.g., a terminal computer), which is disposed outside the low-pressure chamber 6 and is in communication with the data collector 7. The data processed by the data collector 7 can be transmitted to the data feedback system 8 via a network for storage and management.

[0049] In one embodiment, the leakage detection device further comprises a measuring device disposed outside the low-pressure cavity 6 , which comprises a vacuum dial 4 for displaying the vacuum degree in the low-pressure cavity 6 .

[0050] In one embodiment, a vacuum dial 4 is installed on the top of the low-pressure cavity 6 to display the vacuum degree inside the cavity in real time.

[0051] In one embodiment, two valves are provided outside the low-pressure chamber 6, one of which is connected to the external vacuum pump 1; the other is a needle valve connected to a micro-syringe, which is used for accurately injecting electrolyte of a specified concentration for leakage detection testing during the test phase.

[0052] In one embodiment, the vacuum pumping device includes a vacuum pump 1 and an air valve 2 , and the vacuum pump 1 is connected to the low-pressure chamber 6 through the air valve 2 .

[0053] In one embodiment, the vacuum pump 1 is one or a combination of mechanical pumps, molecular pumps, ion pumps, diaphragm pumps, cryogenic pumps, and diffusion pumps; the power of the vacuum pump 1 is 0.18 kW. The vacuum pump 1 is connected to the air valve 2 through a rubber hose. The function of the vacuum pump 1 is to reduce the air pressure in the cavity to the vacuum degree required for the experiment to meet the subsequent test requirements.

[0054] In this embodiment, the vacuum pump 1 performs a vacuum operation on the low-pressure chamber 6. According to the type of the DUT 3, the detection requirements, and the molecular structure of the liquid in the DUT 3, the pressure of the low-pressure chamber 6 is adjusted to a predetermined low-pressure state, usually within 10 -9 Up to 10 5 The low pressure environment in the low pressure chamber 6 can be adjusted according to the different chemical compositions of the liquid in the test element 3 and the linear response range of the corresponding sensor. For example, for the liquid components with strong volatility to be tested, a higher pressure can be selected; while for the components with low volatility, a lower pressure can be used to promote the diffusion and volatilization of the liquid to be tested through the leak hole.

[0055] In one embodiment, the gas sensor 5 includes a semiconductor resistive gas sensor, an electrochemical gas sensor, a catalytic combustion gas sensor, an optical gas sensor, a magnetic gas analysis sensor or a surface acoustic wave gas sensor, that is, includes at least one of the above sensors.

[0056] In one embodiment, the gas sensor 5 is a sensor whose internal gas-sensitive material is tin dioxide. The gas-sensitive material has a relatively stable sensitivity when detecting volatile organic compounds (VOCs). The gas sensor 5 has a resistance of 40kΩ when working, and the gas sensor 5 has two circuits that do not interfere with each other: one circuit is used for heating the sensor, and the other circuit is used for gas detection, both of which need to be powered by 5V voltage. Among them, the role of the heating circuit is to provide the sensor with its necessary working temperature.

[0057] In one embodiment, the device under test 3 includes a new energy battery.

[0058] In one embodiment, the low-pressure chamber 6 is a sealed chamber with a pressure lower than the atmospheric pressure, such as a vacuum vessel. The vacuum vessel is composed of a hemispherical cover and a truncated cone bottom, and has a volume of 10L.

[0059] Reference Figure 3 as well as Figure 4 In one embodiment of the present invention, a method for detecting leakage based on a gas sensor 5 is also provided, in particular, low leakage rate liquid or gas leakage detection, which is used in the leakage detection device in the above embodiment; the above leakage detection device includes a vacuum pumping device, a sealed low-pressure cavity 6 and a gas sensor 5; the vacuum pumping device is arranged outside the low-pressure cavity 6 and is connected to the low-pressure cavity 6, and is used to adjust the vacuum degree of the low-pressure cavity 6; the gas sensor 5 is arranged in the low-pressure cavity 6, and is used to sense the gas concentration generated by the leakage and volatilization of the component to be tested 3 in the low-pressure cavity 6;

[0060] The method comprises:

[0061] Step S1, controlling the element to be tested 3 in the low-pressure cavity 6 to meet the testing conditions;

[0062] Step S2, detecting a gas concentration change signal in the low-pressure cavity 6 by the gas sensor 5;

[0063] Step S3, based on the gas concentration change signal, determining whether the leakage rate of the component to be tested 3 meets the standard.

[0064] In this embodiment, the leakage detection device in the above embodiment is first constructed as a hardware basis. Before starting the detection, the component under test 3 needs to be placed in the above low-pressure cavity 6. At the same time, before the component under test 3 is placed in the vacuum cavity, ensure that the leakage detection device is at a normal ambient temperature to avoid abnormal changes in the component under test 3 due to temperature changes.

[0065] As described in step S1 , in order to test the DUT 3 , it is first necessary to satisfy the test conditions, which include the air pressure in the low-pressure cavity 6 and the leakage time of the DUT 3 in the low-pressure cavity 6 .

[0066] Therefore, in the above step S1, controlling the DUT 3 in the low-pressure chamber 6 to meet the detection conditions includes:

[0067] Based on the vacuum pumping device, the air pressure in the low-pressure chamber 6 is adjusted to a predetermined low-pressure state;

[0068] The low-pressure chamber 6 is kept in a closed state, and the device under test 3 is allowed to continue leaking in the low-pressure chamber 6 for a preset time.

[0069] In order to achieve the above detection conditions, the above vacuum device is first started to vacuum the low-pressure chamber 6. The above predetermined low-pressure state is determined by the type of the element to be tested 3, the detection requirements, the liquid molecular structure in the element to be tested 3 and the linear response range of the gas sensor 5, and is usually controlled within 10 -9 Up to 10 5 For example, for a highly volatile component of the liquid to be tested, a higher pressure can be selected, while for a less volatile component, a lower pressure can be used to promote the diffusion and volatilization of the liquid to be tested through the leak hole.

[0070] As described in the above step S2, after the low-pressure cavity 6 reaches a predetermined low-pressure state, the cavity is kept sealed so that the liquid molecules in the element to be tested 3 leak into the low-pressure cavity 6 to form gas molecules, and the leakage time is determined according to the actual detection requirements. Start the gas sensor 5 to detect the changes in the gas composition in the low-pressure cavity 6 in real time, and the gas sensor 5 will output a corresponding signal according to the concentration changes of the above-mentioned gas molecules. In this embodiment, a low-pressure environment is generated by a vacuum pump and a low-pressure cavity 6. Compared with the normal pressure detection method, the relative concentration of molecules in the environment that competes with the molecules to be detected for adsorption is reduced, and the detection signal of the sensor has an amplification effect on the gas concentration, thereby indirectly improving the detection sensitivity of the gas sensor 5 and reducing the detection limit; in the low-pressure cavity 6, the molecules in the cavity environment are clear, which can effectively avoid the interference of uncertain molecules in the traditional normal pressure detection environment, which is beneficial to improve the accuracy of detecting whether the leakage rate of the element to be tested 3 meets the standard.

[0071] As described in the above step S3, according to the gas concentration change signal collected by the above gas sensor 5, the change of gas concentration in the above low-pressure chamber 6 can be judged, and then it can be determined whether the leakage rate of the component to be tested 3 meets the standard.

[0072] Specifically, the above-mentioned determining whether the leakage rate of the element to be tested 3 meets the standard based on the gas concentration change signal includes:

[0073] Transmitting the gas concentration change signal to the data collector 7;

[0074] Processing the gas concentration change signal based on the data collector 7 to obtain real-time gas concentration;

[0075] Based on the data acquisition device 7, the leakage rate of the element to be tested 3 is calculated according to the gas concentration, the volume of the low-pressure cavity 6 and the internal gas pressure of the low-pressure cavity 6;

[0076] Determining whether the leakage rate is less than a threshold value;

[0077] If it is less than, it is determined that the leakage rate of the component under test 3 meets the standard.

[0078] In this embodiment, the detection signal of the gas sensor 5 is transmitted to the data collector 7 in real time. The data collector 7 can record the concentration change of the gas in the low-pressure cavity 6 and generate a real-time gas concentration curve. By analyzing the detection data, it can be determined whether there is liquid leakage in the component under test 3.

[0079] Specifically, by analyzing the data by the data acquisition device 7, it can be determined whether there is a risk of leakage in the component under test 3. Based on the data acquisition device 7, the data acquisition device 7 calculates the leakage rate of the component under test 3 according to the gas concentration, the volume of the low-pressure cavity 6, and the internal air pressure of the low-pressure cavity 6, and determines whether the leakage rate is greater than a threshold value. If it is, the data acquisition device 7 will issue an alarm, indicating that there is a liquid leakage in the component under test 3. The above thresholds can be pre-set according to different types of components under test 3 and leakage standards. The component under test 3 for which the data acquisition device 7 issues an alarm is re-inspected. If the data acquisition device 7 still alarms during the re-inspection, it is considered that the leakage rate of the component under test 3 does not meet the standard and can be discarded.

[0080] Therefore, in one embodiment, after determining whether the leakage rate is less than a threshold, the method further includes:

[0081] If it is not less than, a warning is issued and it is determined whether it is the first leak rate detection;

[0082] If yes, then re-enter the step of controlling the component to be tested 3 in the low-pressure cavity 6 to meet the test conditions for re-testing;

[0083] If not, it is determined that the leakage rate of the component under test 3 does not meet the standard and is scrapped.

[0084] In the above embodiment, the calculation formula of the leakage rate is:

[0085]

[0086] In one embodiment, when the data collector 7 processes the gas concentration change signal to obtain the real-time gas concentration, the noise in the signal is first filtered out by a hybrid filtering method combining wavelet transform and adaptive filtering algorithm. The wavelet transform is used to perform multi-resolution analysis on the signal and decompose the signal into sub-bands of different frequencies. The adaptive filtering algorithm dynamically adjusts the filtering parameters according to the noise characteristics of the gas sensor 5 under different air pressures, temperatures and different types of leakage gas components of the element to be tested 3, and accurately removes the noise in each sub-band to significantly improve the accuracy of gas concentration measurement.

[0087] At the same time, the real-time gas concentration data is compared and analyzed with the historical detection data. If the gas concentration fluctuation value detected for multiple consecutive times exceeds the set fluctuation threshold, not only the vacuum device and the gas sensor 5 are calibrated and checked, but also the simulation analysis of the airflow field inside the low-pressure cavity 6 is started. Real-time airflow data is obtained by using multiple micro airflow sensors arranged in the low-pressure cavity 6, and the airflow distribution in the low-pressure cavity 6 is simulated in combination with the computational fluid dynamics algorithm to check whether there is a gas concentration measurement deviation caused by abnormal airflow. If the calibration check and the airflow field analysis results are normal, it is determined that the component to be tested 3 may have an unstable leakage, and the preset time is further extended for detection, and the gas concentration data during the extended detection period is stored separately for subsequent fault analysis. In addition, for the gas concentration data detected each time, a prediction model is established using a machine learning algorithm, and the subsequent possible gas concentration change trend is predicted by continuously training the model to detect potential leakage anomalies in advance.

[0088] In another embodiment, after the warning is issued, if the detection step is re-entered and the re-detection result still does not meet the standard, before determining that the leakage rate of the component to be tested 3 does not meet the standard and is scrapped, a local microenvironment analysis is performed on the component to be tested 3, and a microsensor array is used to detect parameters such as temperature, humidity, and electromagnetic field around the component to be tested 3 to determine whether there is an abnormal leakage rate caused by external environmental factors. If so, the external environmental protection measures of the low-pressure cavity 6 are adjusted and a third detection is performed. If the third detection still does not meet the standard, it is determined that the leakage rate of the component to be tested 3 does not meet the standard and is scrapped.

[0089] In the above embodiment, before using the above leakage detection device for detection, it is also necessary to test it to verify its effectiveness.

[0090] In this embodiment, the following test process is proposed to perform example testing.

[0091] Example 1

[0092] 1. Test Preparation

[0093] (1) Low-pressure chamber 6: A commercial vacuum dish is used as the low-pressure chamber 6. The low-pressure chamber 6 is composed of a hemispherical cover and a truncated cone bottom, and has a volume of 10L. A vacuum dial 4 is installed on the top of the chamber, which can display the vacuum degree inside the low-pressure chamber 6 in real time. On the outside of the chamber, there are two valves: one is connected to the external vacuum pump 1, and the other is a needle valve connected to a micro-injector, which is used to accurately inject an electrolyte of a specified concentration. The above-mentioned low-pressure chamber 6 is reasonably designed, has excellent sealing performance, and can stably maintain a low-pressure environment.

[0094] (2) Vacuum pumping device: The power of the external vacuum pump 1 is 0.18 kW, and the vacuum pump 1 is connected to the air valve 2 of the low-pressure chamber 6 through a rubber hose. The function of the vacuum pump 1 is to reduce the air pressure in the low-pressure chamber 6 to the vacuum degree required for the experiment to meet the requirements of subsequent tests.

[0095] (3) Gas sensor 5: The gas sensor 5 used has a gas-sensitive material of tin dioxide (SnO2) inside, which has a relatively stable sensitivity when detecting volatile organic compounds (VOCs). The resistance of the above-mentioned gas sensor 5 is about 40kΩ when working. The gas sensor 5 has two circuits that do not interfere with each other: one circuit is used for heating the sensor, and the other circuit is used for gas detection. Both circuits need to be powered by 5V voltage. The heating circuit provides the necessary working temperature for the gas sensor 5.

[0096] (4) Data collector 7: can accurately record the resistance or current changes of the sensor under different conditions and convert these signals into data for subsequent analysis.

[0097] (5) Electrolyte: The electrolyte to be tested is a commercial secondary electrolyte LB-030, whose main components are ethylene carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC), with a component ratio of 1:1:1 and a concentration of 1 mol / L. The above electrolyte is widely used in new energy batteries, has a certain volatility, and is suitable for leakage testing.

[0098] Test process: First, prepare the semiconductor resistance type gas sensor 5 and the commercial secondary electrolyte LB-030. Install the gas sensor 5 in the low-pressure cavity 6 and ensure that it is connected to the data acquisition device 7 to record data in real time. Then, connect the vacuum pump 1 to the gas valve 2 of the low-pressure cavity 6 through a rubber hose, start the vacuum pump 1, and start the vacuum operation of the low-pressure cavity 6. The air pressure in the low-pressure cavity 6 is pumped to one-fifth of the atmospheric pressure, and the vacuum dial 4 shows 0.02MPa. Under this low-pressure state, use a micro-syringe to inject 2.5μL of secondary electrolyte into the cavity. The concentration of the injected electrolyte is 25ppm. The injected electrolyte will evaporate over time and release volatile VOCs. After the electrolyte is injected, the gas sensor 5 begins to detect changes in gas concentration. At this time, the resistance change (reaction gas concentration change signal) output by the gas sensor 5 is recorded by the data acquisition device 7. The data acquisition device 7 can accurately capture the response of the gas sensor 5 to VOCs and generate a resistance-time curve in real time. When the resistance of the sensor stabilizes, it means that the gas concentration has reached an equilibrium point, and the recorded resistance value can reflect the leakage of the electrolyte.

[0099] In order to verify the influence of low pressure state on detection sensitivity, a set of comparative tests was conducted. The comparative test steps are similar to the above low pressure experiment, except that the vacuum pump 1 is not used for evacuation, and the low pressure cavity 6 is maintained at normal pressure. Similarly, a micro syringe is used to inject 2.5 μL of secondary electrolyte into the low pressure cavity 6, and the resistance change of the sensor is recorded by the data acquisition device 7.

[0100] By comparing the detection sensitivity of gas sensor 5 to electrolyte of the same concentration under low pressure and normal pressure, the detection limit of gas sensor 5 to VOCs gas under low pressure is significantly improved. Specifically, under low pressure, the resistance response of gas sensor 5 to the same amount of volatile gas from electrolyte is stronger and the sensitivity is higher. Under normal pressure, the response of gas sensor 5 to VOCs is weaker and the sensitivity is lower.

[0101] Example 2

[0102] In this example, what is different from Example 1 is that when testing under low-pressure conditions, 0.5 μL (5 ppm) of secondary electrolyte is added; under normal pressure testing conditions, 2.5 μL (25 ppm) of secondary electrolyte is added, and the other conditions are exactly the same as in Example 1. The test results show that under low-pressure conditions, the concentration of the secondary electrolyte shows an obvious amplification effect.

[0103] Example 3

[0104] In this example, in order to verify the reliability of low-pressure assistance in battery electrolyte leakage detection, a test experiment was carried out on an actual battery. In the specific operation, a battery with a tiny leak hole is placed in a closed low-pressure cavity 6 with a volume of 10L, and the pressure in the low-pressure cavity 6 is reduced to 0.02MPa by a vacuum pump 1 to create a low-pressure assistance condition. Under this low-pressure state, the liquid molecules in the battery leak within 3600s, and the changes in the concentration of the leaked gas in the low-pressure cavity 6 are recorded by the gas sensor 5. Finally, the gas concentration was measured to be 4.8ppm under this condition. According to the following formula for battery leakage rate:

[0105]

[0106] Substituting various parameters, the leakage rate of the product can be calculated to be approximately 1.61×10 -7 Pa·m 3 / s, and compared with the experiment under the same conditions under normal pressure, the results show that under normal pressure conditions, the concentration of the leak gas is still at the ppb level after accumulating for 1 hour, which is lower than the detection limit of the gas sensor 5 and cannot be sensed by the sensor. Under low-pressure auxiliary conditions, the concentration of the gas increased significantly after leaking in the container, reaching the ppm level relatively, so that the gas sensor 5 can effectively detect the concentration. The low-pressure environment not only accelerates the volatilization of the gas inside the battery by reducing the internal pressure, but also amplifies the concentration of the leaked gas to a certain extent, making it consistent with the detection range of the sensor, thereby achieving high-sensitivity detection of trace leaks, providing an efficient and reliable method for battery sealing and safety assessment.

[0107] Example 4

[0108] In this example, a new energy battery is used as the detection object. The difference from the third embodiment is that the volume of the sealed low-pressure chamber 6 is 1L, the volatilization time of the liquid molecules in the battery is 360s, and the other parameters are the same as those in the third embodiment. The gas concentration is determined to be 4.8ppm through the resistance change ratio of the gas sensor 5, and the leakage rate of the sample to be detected is calculated to be 1.61×10 -7 Pa·m 3 / s.

[0109] Example 5

[0110] In this example, a small-volume new energy battery is used as the detection object. The difference from Example 3 is that the volume of the sealed low-pressure chamber 6 is 0.5L, the volatilization time of the electrolyte molecules in the battery is 360s, and the other parameters are the same as those in Example 3. The gas concentration is determined to be 1ppm through the resistance change ratio of the gas sensor 5, and the leakage rate of the sample to be tested is calculated to be 1.68×10 -8 Pa·m 3 / s.

[0111] Through the above test examples, it can be concluded that: by using the vacuum device and the low-pressure chamber 6 to generate a low-pressure environment, compared with the normal pressure detection method, the relative concentration of molecules in the environment that compete with the molecules to be detected for adsorption is reduced, and the detection signal of the sensor has an amplification effect on the gas concentration, thereby indirectly improving the detection sensitivity of the gas sensor 5 and reducing the detection limit; in the low-pressure chamber 6, the molecules in the environment inside the chamber are clear, which can effectively avoid the interference of uncertain molecules in the traditional normal pressure detection environment, which is beneficial to improve the accuracy of detecting whether the leakage rate of the element to be tested 3 meets the standard.

[0112] In another embodiment of the present invention, a device for detecting leakage based on a gas sensor 5 is provided, and the device is used to execute any of the methods described above.

[0113] In summary, the method and device for detecting leakage based on the gas sensor 5 provided in the embodiment of the present invention are used for a leakage detection device, and the leakage detection device includes: a vacuum device, a sealed low-pressure cavity 6 and a gas sensor 5; the vacuum device is arranged outside the low-pressure cavity 6 and is connected to the low-pressure cavity 6, and is used to adjust the vacuum degree of the low-pressure cavity 6; the gas sensor 5 is arranged in the low-pressure cavity 6, and is used to sense the gas concentration generated by the leakage and volatilization of the component to be tested 3 in the low-pressure cavity 6; the method includes: controlling the component to be tested 3 in the low-pressure cavity 6 to meet the detection conditions; detecting the gas concentration change signal in the low-pressure cavity 6 by the gas sensor 5; and determining whether the leakage rate of the component to be tested 3 meets the standard based on the gas concentration change signal. In the present invention, a low-pressure environment is generated by a vacuum device and a low-pressure cavity 6 to reduce the competitive adsorption of gas molecules in a normal pressure environment and gas molecules volatilized by the component to be tested on the sensor surface. Compared with the normal pressure detection method, since the relative concentration of molecules in the environment that compete with the molecules to be detected for adsorption is reduced, the detection signal of the sensor has an amplification effect on the gas concentration, thereby indirectly improving the detection sensitivity of the gas sensor 5 and reducing the detection limit; in the low-pressure cavity 6, the molecules in the cavity environment are clear, which can effectively avoid the interference of uncertain molecules in the traditional normal pressure detection environment, which is beneficial to improving the accuracy of detecting whether the leakage rate of the element to be tested 3 meets the standard.

[0114] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0115] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for detecting leakage based on a gas sensor, characterized in that: A leak detection device, the leak detection device comprising a vacuum device, a sealed low-pressure cavity and a gas sensor; the vacuum device is arranged outside the low-pressure cavity and is connected to the low-pressure cavity, and is used to adjust the vacuum degree of the low-pressure cavity; the gas sensor is arranged in the low-pressure cavity, and is used to detect the concentration of gas volatilized by the leakage of the component to be tested in the low-pressure cavity; The method comprises: Controlling the element to be tested in the low-pressure cavity to meet the testing conditions; Detecting a gas concentration change signal in the low-pressure cavity by the gas sensor; Based on the gas concentration change signal, determine whether the leakage rate of the component to be tested meets the standard.

2. The method for detecting leakage based on a gas sensor according to claim 1, characterized in that: Controlling the element to be tested in the low-pressure cavity to meet the testing conditions includes: Based on the vacuum pumping device, adjusting the air pressure in the low-pressure chamber to a predetermined low-pressure state; The low-pressure cavity is kept in a closed state, and the element to be tested continues to leak in the low-pressure cavity for a preset time.

3. The method for detecting leakage based on a gas sensor according to claim 2, characterized in that: The predetermined low pressure state is determined by the type of the element to be tested, the detection requirements, the molecular structure of the liquid or gas in the element to be tested, and the linear response range of the gas sensor.

4. The method for detecting leakage based on a gas sensor according to claim 1, characterized in that: The step of determining whether the leakage rate of the component under test meets the standard based on the gas concentration change signal includes: Transmitting the gas concentration change signal to a data acquisition device; Processing the gas concentration change signal based on the data collector to obtain real-time gas concentration; Based on the data acquisition device, the leakage rate of the component to be tested is calculated according to the gas concentration, the volume of the low-pressure cavity and the internal gas pressure of the low-pressure cavity; Determining whether the leakage rate is less than a threshold value; If it is less than, it is determined that the leakage rate of the component to be tested meets the standard.

5. The method for detecting leakage based on a gas sensor according to claim 4, characterized in that: After determining whether the leakage rate is less than a threshold, the method further includes: If it is not less than, a warning is issued and it is determined whether it is the first leak rate detection; If yes, re-entering the step of controlling the component to be tested in the low-pressure cavity to meet the test condition for re-testing; If not, it is determined that the leakage rate of the component under test does not meet the standard and is scrapped.

6. The method for detecting leakage based on a gas sensor according to claim 4, characterized in that: The calculation formula of the leakage rate is:

7. The method for detecting leakage based on a gas sensor according to any one of claims 1 to 6, characterized in that: The gas sensor includes a semiconductor resistance gas sensor, an electrochemical gas sensor, a catalytic combustion gas sensor, an optical gas sensor, a magnetic gas analysis sensor or a surface acoustic wave gas sensor.

8. The method for detecting leakage based on a gas sensor according to any one of claims 1 to 6, characterized in that: The component to be tested includes a new energy battery.

9. The method for detecting leakage based on a gas sensor according to any one of claims 1 to 6, characterized in that: The low-pressure cavity is a sealed cavity with a pressure lower than the atmospheric pressure.

10. A device for detecting leakage based on a gas sensor, characterized in that: The device is used to perform the method as claimed in any one of claims 1 to 9.

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