Positive pressure helium detection device and positive pressure helium detection method

Abstract

The invention belongs to the technical field of battery detection, and mainly relates to a positive pressure helium detection device which comprises an assembly cavity used for assembling a battery cell, the assembly cavity is connected with a helium detector through a first pipeline, and the first pipeline is provided with a first vacuum gauge used for measuring air pressure in the assembly cavity and a first vacuum pump used for extracting air in the assembly cavity; the battery cell is connected with the helium tank through a second pipeline; the second pipeline is provided with a second vacuum gauge for measuring the air pressure in the battery cell and a second vacuum pump for extracting air in the battery cell; through the above design, detection of different degrees of leakage points of the battery cell in the positive pressure helium detection process can be realized, and meanwhile, a large leakage point can be detected through the vacuum gauge before helium injection, so that detection resources are saved. Meanwhile, the invention further relates to a positive pressure helium detection method, the detection cost is further reduced, and the detection efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of battery detection, and in particular relates to a positive pressure helium detection device and a positive pressure helium detection method. Background Art

[0002] As the main power source of new energy vehicles, the quality of square batteries directly affects the stability and safety of new energy vehicle power. As an important indicator of square battery quality, air tightness is currently a key issue for manufacturers, and how to conduct square battery air tightness testing is the key to judging air tightness.

[0003] In the current technical field, especially in the production process of square batteries, after the welding around the aluminum shell is completed, the positive pressure helium inspection process is often used to effectively identify potential defects such as weld sand holes, battery cover venting valve membrane damage or micropores. This measure does help prevent these defects from causing problems such as electrolyte leakage in subsequent processes. However, the current positive pressure helium inspection process mainly relies on helium detectors to determine the leak rate (see GB / T 36176-2018 "Vacuum Technology Helium Mass Spectrometry Vacuum Leak Detection Method"). This method ignores the fact that the change in air pressure in the helium hood or helium cavity during the positive pressure helium inspection process can also reflect whether there is a leak in the component to be tested. In addition, positive pressure helium inspection mainly performs precise detection of tiny leaks, and there is no need to detect the leak rate for larger leaks. Therefore, relying solely on the above-mentioned detection methods may lead to unnecessary waste of detection resources.

[0004] Based on this, there is an urgent need to improve the existing positive pressure helium detection device and positive pressure helium detection method to solve the defects of the above-mentioned technology. Summary of the invention

[0005] One of the purposes of the present invention is to provide a positive pressure detection device to address the deficiencies of the prior art, and to provide timely feedback through a pressure gauge on the pressure values ​​of the cell and the assembly cavity during the positive pressure helium inspection of a square battery to determine what kind of cell leakage point has occurred.

[0006] In order to achieve the above objectives, this application implements the following technical solutions:

[0007] A positive pressure helium detection device comprises an assembly chamber for assembling electric cells, wherein the assembly chamber is connected to a helium detector via a first pipeline, the first pipeline is equipped with a first vacuum gauge for measuring the internal air pressure of the assembly chamber and a first vacuum pump for extracting air from the assembly chamber; the electric cell is connected to a helium cylinder via a second pipeline, the second pipeline is equipped with a second vacuum gauge for measuring the internal air pressure of the electric cell and a second vacuum pump for extracting air from the electric cell.

[0008] The above technical solution produces the following technical effects:

[0009] By installing vacuum gauges in the first and second pipes, we can accurately control the pressure changes in the battery cells during the positive pressure helium inspection. This improvement makes it possible to effectively identify larger leaks in the battery cells before using the helium detector for helium rate testing, thereby saving testing resources and enabling the detection of different leaks.

[0010] As a further improvement of the positive pressure helium detection device of the present invention, the first pipeline is equipped with a first valve, and the first valve is used to control the communication between the helium detector and the assembly cavity;

[0011] The second pipeline is equipped with a second valve, and the second valve is used to control the connection between the helium cylinder and the battery cell.

[0012] As a further improvement of the positive pressure helium detection device of the present invention, the first vacuum pump is connected to the first pipeline through a first branch pipe, and the first branch pipe is equipped with a third valve;

[0013] Furthermore, the second vacuum pump is connected to the second pipeline through a second branch pipe, and the second branch pipe is equipped with a second valve.

[0014] The second purpose of the present invention is to provide a positive pressure helium detection method to address the deficiencies of the prior art, which can detect different degrees of battery cell leakage points and prevent those battery cells with obvious leakage points from causing damage to the helium detector when passing through the helium detector.

[0015] In order to achieve the above technical objectives, this application implements the following technical solutions:

[0016] A positive pressure helium detection method, using any of the positive pressure helium detection devices mentioned above, wherein the detection steps are as follows:

[0017] S101, assembling the battery cell in the assembly cavity and sealing the assembly cavity;

[0018] S201, evacuating the assembly chamber for the first time by using a first vacuum pump; judging whether a first leak point occurs in the battery cell based on a change in a second vacuum count value, and proceeding to the next step if no first leak point occurs;

[0019] S301, evacuating the assembly chamber for the second time by using a first vacuum pump, and evacuating the battery cell for the first time by using a second vacuum pump;

[0020] S401, the helium cylinder injects helium into the liquid injection port of the battery cell through the second pipeline;

[0021] During the helium injection stage, based on the change in the first vacuum count value, it is determined whether the battery cell has a second leak point, and if no second leak point occurs, the next step is performed;

[0022] S501, the first vacuum pump evacuates the assembly chamber for the third time, and after the assembly chamber reaches a predetermined pressure value, the first vacuum pump is turned off, and the helium detector collects the helium leak rate;

[0023] Determine whether the battery cell has a third leak point based on the helium leak detection rate;

[0024] S601. After restoring the air pressure in the battery cell and the assembly chamber, take out the battery cell.

[0025] The above technical solution produces the following technical effects:

[0026] By classifying the possible leaks of square cells into three categories and testing them in sequence from larger leaks to smaller leaks, not only is unnecessary waste of testing resources avoided (for example, when a larger leak is detected, the subsequent helium injection process is stopped) but also damage to the helium detection instrument is avoided.

[0027] As a further improvement of the positive pressure helium detection method of the present invention, the method for determining the first leak point in step S201 is:

[0028] S202, obtaining the value A of the second vacuum gauge in step S101 1 Before the assembly chamber is evacuated to 40 Pa in step S201, the value A of the second vacuum gauge is obtained. 2 , if A 1 -A 2 ≤A 0 , determine that the first leakage point appears in the battery cell.

[0029] As a further improvement of the positive pressure helium detection method of the present invention, in step S302, A 0 The value range is 10000-16000, and the unit is Pa.

[0030] As a further improvement of the positive pressure helium detection method of the present invention, the method for determining the second leakage point in step S401 is:

[0031] S402, before the helium injection stage, obtain the value B of the first vacuum gauge 1 , during the helium injection stage, the value of the first vacuum gauge B 2 , if B 2 -B 1 ≥B 0 , it is determined that the battery cell has a second leakage point.

[0032] As a further improvement of the positive pressure helium detection method of the present invention, in step S402, B 0 The value range is 120-40, B 1 The value is 40, and the unit is Pa.

[0033] As a further improvement of the positive pressure helium detection method of the present invention, the predetermined air pressure value in step S501 is any value between 4 and 40, with the unit being Pa.

[0034] As a further improvement of the positive pressure helium detection method of the present invention, the method for determining the third leak point in step S501 is:

[0035] S502, during a collection cycle of the helium detector, the collected leakage rate is compared with the third leakage point judgment value; if the collected leakage rate is greater than the third leakage point judgment value, it is determined that the battery cell has a third leakage point;

[0036] The acquisition time of one acquisition cycle of the helium detector is 5S; the third leak point judgment value is 5*10 -7 , unit is Pa*m 3 / s. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 This is a schematic diagram of the structure of Example 1 of the present invention;

[0039] Figure 2 This is a flow chart of Example 2 of the present invention;

[0040] in:

[0041] 1-Battery cell;

[0042] 11- Second pipeline;

[0043] 111- second valve;

[0044] 112-Second Division;

[0045] 12- second vacuum gauge;

[0046] 13- second vacuum pump;

[0047] 131 - fourth valve;

[0048] 2-Assembly cavity;

[0049] 21- first pipeline;

[0050] 211- first valve;

[0051] 212-First Division;

[0052] 22- first vacuum gauge;

[0053] 23- first vacuum pump;

[0054] 231 - third valve;

[0055] 3-Helium detector;

[0056] 4-Helium tank. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0058] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In order to make the purpose, technical solution and advantages of the embodiment of the present application clearer, the embodiment of the present application will be further described in detail with reference to the accompanying drawings. Below, some terms in the embodiment of the present application are explained to facilitate understanding by those skilled in the art.

[0060] Helium mass spectrometry leak detection (helium detection method) uses helium as the leak detection gas. Since helium has a very small content in the air, small molecules, and light weight, it is easy to pass through the leak hole. Moreover, helium is non-toxic, colorless, non-flammable, non-condensing, and completely inert chemically. After entering the system, it flows and diffuses quickly, and is not interfered by other gases during the leak detection process. Therefore, it is an excellent selective leak detection method that is sensitive and can detect extremely small leaks.

[0061] Vacuum breaking refers to the pressure that needs to be set in order to restore to normal atmospheric conditions after completing a specific test or operation. In the positive pressure helium inspection process of square lithium batteries described in the document, there are two vacuum breaking setting values, namely the assembly vacuum breaking setting value and the battery cell vacuum breaking setting value. These two values ​​represent the target pressure levels in the process of gradually restoring the low pressure state in the assembly and battery cell to a pressure close to the standard atmospheric pressure.

[0062] Sand holes refer to tiny holes or cracks produced after welding. These defects may appear on the welds of the battery core and the venting valve membrane on the battery cover. They will cause problems such as liquid leakage in subsequent processes, thus affecting the safety and performance of the battery.

[0063] A vacuum gauge is an instrument used to measure pressure in a vacuum environment. In the positive pressure helium inspection process of square lithium batteries, the vacuum gauge is used to accurately collect the changes in the pressure inside the battery cell and the pressure inside the assembly, so as to determine whether the battery cell has leakage or other problems. Specifically, the process uses two types of vacuum gauges, namely a battery vacuum gauge for measuring the internal pressure of the battery and an assembly vacuum gauge for measuring the internal pressure of the assembly.

[0064] A vacuum pump is a device that can extract gas from a confined space to create a vacuum environment. Its working process is to create a low-pressure area, so that the air or other gas molecules in the area are extracted into the external environment. In fact, the vacuum pump is mainly used to create negative pressure conditions, that is, a state of lower pressure relative to atmospheric pressure. The "positive pressure" mentioned refers to the pressure state generated in a "container" that is higher than the external atmospheric pressure. In this application, the "positive pressure" environment is achieved through a helium cylinder.

[0065] Helium purification is a step in the positive pressure helium inspection process for square lithium batteries. It means that after the helium leak test is completed, helium is extracted from the battery cell until a preset pressure value is reached. This process is to remove the residual helium inside the battery cell to avoid interference or contamination to subsequent processes.

[0066] Standard atmospheric pressure refers to the average atmospheric pressure at sea level at a temperature of 15 degrees Celsius, and its value is defined as 101325 Pascals (Pa), or 100,000 Pascals for simplification. The standard atmospheric pressure mentioned in the patent application is 100,000 Pascals, which is an idealized approximation for the convenience of calculation and does not mean the real atmospheric pressure in actual measurement. In fact, due to the influence of factors such as geographical location and weather conditions, the real atmospheric pressure may be different.

[0067] The leak rate usually refers to the amount of gas leaking from one space to another within a certain period of time. It is used to measure the airtightness of a system or the degree of sealing between components. In the mentioned square lithium battery positive pressure helium inspection process, the leak rate is measured by a helium detector. Within a specific time interval (for example, 5 seconds), if the leak rate exceeds the predetermined standard, it is considered that the test object has a slight leak. Among them, the leakage amount is the realization benchmark of the leak rate. In the positive pressure helium inspection device of the present application, the collected helium leakage amount is reflected in the actual value of the helium rate in the positive pressure helium inspection process.

[0068] It is known that in the prior art, helium detectors are usually used to detect whether there are defects such as sand holes and pinholes in the welds and whether the vent valve membrane is damaged, so as to prevent leakage and other problems that may occur in subsequent processes. The basic principle is to use helium as a tracer gas and inject it into the battery cell or test environment under high pressure. Since helium molecules are small and active, they can easily escape from any small leak point. Then, a highly sensitive helium mass spectrometer is used to capture the escaped helium to determine the sealing performance of the product. However, this method may ignore the important step of evaluating the sealing status by monitoring the pressure changes in the system.

[0069] In addition, for some square leaks with larger leaks, positive pressure helium detection is not suitable, but separate detection results in low detection efficiency and high detection resources. Therefore, this application provides an improved solution, which needs to combine pressure changes and helium detection methods for comprehensive judgment, so that not only can subtle leaks be found, but also larger leaks can be identified, which improves detection accuracy and equipment efficiency and reduces helium consumption.

[0070] Although the present application is disclosed as follows in the form of a preferred embodiment, it is not intended to limit the claims. Any person skilled in the art may make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

[0071] The present invention is further described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0072] Example 1

[0073] like Figure 1 As shown, in order to realize the detection of different types of leaks through the changes in the air pressure in the assembly chamber 2 and the battery cell 1 during the positive pressure helium process of the square battery cell 1, the present application specifically provides an improved positive pressure helium detection device, including an assembly chamber 2 for assembling the battery cell 1, wherein the assembly chamber 2 is connected to the helium detector 3 through a first pipe 21, and the first pipe 21 is equipped with a first vacuum gauge 22 for measuring the air pressure inside the assembly chamber 2 and a first vacuum pump 23 for extracting air from the assembly chamber 2; the battery cell 1 is connected to the helium cylinder 4 through a second pipe 11, and the second pipe 11 is equipped with a second vacuum gauge 12 for measuring the air pressure inside the battery cell 1 and a second vacuum pump 13 for extracting air from the battery cell 1.

[0074] In the above technical solution, the first vacuum pump 23 and the second vacuum pump are used to put the battery cell 1 and the assembly chamber 2 in a negative pressure environment, so that the air or other gas molecules in the storage area of ​​the battery cell 1 and the assembly chamber 2 are extracted to the external environment. In this process, the present application does not extract air from the battery cell 1 and the assembly chamber 2 at the same time, but preferentially extracts air from the assembly chamber 2. Since the air pressure in the assembly chamber 2 is lower than the air pressure in the battery cell 1, if a large leak occurs in the battery cell 1 or a large number of small leaks gather to form a collection of leaks that can automatically flow the air or residual gas inside the battery cell 1 into the assembly chamber 2 due to the pressure difference, the air pressure inside the battery cell 1 will change rapidly. And just because there is a significant leak in the battery cell 1, its internal gas will be quickly released to the assembly chamber 2, causing the air pressure inside the assembly chamber 2 to rise abnormally, so that the second vacuum gauge 12 captures this change, and the staff can judge whether there is an obvious leak by observing this change. (In this application, this leak is defined as the first leak).

[0075] Furthermore, after the pre-vacuum treatment of the existing positive pressure helium inspection, the helium bottle 4 fills the battery cell 1 with helium through the second pipe 11, and the second vacuum gauge 12 monitors the air pressure changes inside the battery cell 1 in real time. Since helium has extremely high diffusivity and extremely small molecular weight, it can quickly penetrate and fill every corner inside the battery cell 1, including those tiny cracks or sand holes. If the battery cell 1 has such defects, helium will overflow from these locations and enter the assembly cavity 2 or the external environment. At this time, the first vacuum gauge 22 comes into play. It is responsible for monitoring the air pressure changes in the assembly cavity 2 caused by the escape of helium, thereby determining whether a leak point slightly lower than the above-mentioned first leak point occurs.

[0076] Furthermore, the helium detector 3 samples and analyzes the gas in the assembly chamber 2 through the first pipe 21 to detect whether there is a helium component, and the helium detector 3 collects the leakage amount to calculate the leakage rate data and finally compares it with the pre-set standard value. If the actual measured leakage rate is higher than this standard value, it is considered that there is a small leakage, that is, a micro-leak; on the contrary, if it is lower than the standard value, it is considered qualified, indicating that no significant leakage is detected. This method based on the readings of the helium detector 3 can accurately identify very subtle leakages, ensuring the quality and safety of the product.

[0077] It is worth noting that during the entire detection process, the changes in the air pressure inside the assembly cavity 2 and the battery cell 1 are continuous and dynamic, which not only reflects the filling and escape of helium, but also indirectly reveals the sealing performance and possible defects of the battery cell 1. Therefore, the present application achieves a comprehensive and accurate evaluation of the sealing performance of the battery cell 1 by combining pressure changes and helium detection.

[0078] Furthermore, the first pipeline 21 is equipped with a first valve 211, and the first valve 211 is used to control the connection between the helium detector 3 and the assembly chamber 2; the second pipeline 11 is equipped with a second valve 111, and the second valve 111 is used to control the connection between the helium bottle 4 and the battery cell 1. Through the control of the first valve 211 and the second valve 111, the positive pressure helium detection device of the present application can respond to different detection requirements more flexibly, ensuring the efficiency and accuracy of the detection process. Specifically, the first valve 211 is opened when the helium detector 3 performs sampling and analysis, so that the gas in the assembly chamber 2 can smoothly enter the helium detector 3 for component detection, thereby accurately determining whether there is a helium leak. During the non-detection period, the first valve 211 remains closed to prevent external gas from interfering with the air pressure in the assembly chamber 2, thereby ensuring the accuracy of the detection data.

[0079] Similarly, the second valve 111 is opened when helium needs to be filled into the battery cell 1, ensuring that the helium can smoothly and efficiently enter the battery cell 1 and complete the helium permeation process of the entire battery cell 1. After the filling is completed or when it is not necessary to continue filling, the second valve 111 is quickly closed to prevent unnecessary waste of helium and possible leakage risks, while also maintaining the pressure stability in the helium cylinder 4 and extending the service life of the equipment.

[0080] In addition, the present application also takes into account the safety and stability during the detection process. During the negative pressure treatment stage of the battery cell 1 and the assembly chamber 2, by strictly controlling the pumping rate and working time of the first vacuum pump 23 and the second vacuum pump 13, excessive fluctuations in internal air pressure caused by pumping too fast or too slow are avoided, thereby reducing the risk of damage to the internal structure of the battery cell 1 or sealing failure of the assembly chamber 2 caused by sudden changes in air pressure.

[0081] Further, the first vacuum pump 23 is connected to the first pipeline 21 through the first branch pipe 212, and the first branch pipe 212 is equipped with a third valve 231; the second vacuum pump 13 is connected to the second pipeline 11 through the second branch pipe 112, and the second branch pipe 112 is equipped with a fourth valve 131. Specifically, the first branch pipe 212 is used to independently vacuum the assembly chamber 2 when the first valve 211 is not opened, and the second branch pipe 112 is responsible for independently vacuuming the inside of the battery cell 1 before the battery cell 1 is filled with helium. The specific working mode of such a design is: when the vacuum treatment of the assembly chamber 2 is performed, the third valve 231 is opened, allowing the first vacuum pump 23 to efficiently extract the negative pressure of the assembly chamber 2 through the first branch pipe 212. At this time, the fourth valve 131 remains closed to prevent the air pressure inside the battery cell 1 from being affected by the treatment process of the assembly chamber 2. This step ensures that the air pressure inside the assembly chamber 2 can be quickly and stably reduced to a predetermined level, creating an ideal environment for subsequent battery cell 1 testing.

[0082] Further, after the assembly chamber 2 reaches the desired negative pressure state, the third valve 231 is closed, the fourth valve 131 is opened, and the second vacuum pump 13 is started. Through the second branch pipe 112, the second vacuum pump 13 performs independent vacuum treatment on the inside of the battery cell 1. The purpose of this step is to further remove the air or impurities that may remain inside the battery cell 1, to ensure that the helium can more accurately penetrate into every corner of the battery cell 1 after being filled, and to improve the sensitivity and accuracy of the detection.

[0083] Furthermore, the first valve 211 is installed between the helium detector 3 and the first branch pipe 212, and the second valve 111 is installed between the helium bottle 4 and the second branch pipe 112. In addition, a liquid injection port is provided at the battery cell 1 for the helium bottle 4 to inject helium into the battery cell 1 through the second pipe 11. The liquid injection port and the liquid injection hole for injecting electrolyte into the battery can be the same, or can be a separate port position. In actual application, it is only necessary to seal the liquid injection hole with a seal.

[0084] In summary, the present application not only solves the problems of low detection efficiency and high resource consumption in the prior art through the improved positive pressure helium detection device, but also improves the detection accuracy and equipment utilization efficiency.

[0085] Example 2

[0086] like Figure 1-2 As shown, the difference from Example 1 is that: in order to further improve the existing positive pressure helium detection process, the present application designs a positive pressure helium detection method, using any of the above-mentioned positive pressure helium detection devices, and the detection steps are as follows:

[0087] S101, assembling the battery cell 1 in the assembly cavity 2, and sealing the assembly cavity 2;

[0088] S201, evacuate the assembly chamber 2 for the first time through the first vacuum pump 23; based on the change in the value of the second vacuum gauge 12, determine whether the battery cell 1 has the first leak point, if not, proceed to the next step; this step is intended to monitor the pressure change in the assembly chamber 2 (i.e., the value change of the first vacuum gauge 22), and preliminarily determine whether the battery cell 1 has an obvious leak point, i.e., the first leak point. If no leakage is found, proceed to the next step. Note that if the first leak point appears, it is an unqualified product and no further testing is required.

[0089] Furthermore, when positive pressure helium detection is performed under existing technical conditions, if the first leak point (detected by air pressure change) is not detected, helium will continue to be injected into the battery cell 1 when there is an obvious hole in the tested battery cell 1. The helium that should have been injected into the battery will flow along the hole to the assembly with lower pressure. In this way, a large amount of unnecessary helium loss will occur. The detection method of the present application determines whether the first leak point occurs through the change in air pressure, thereby avoiding the above situation where the battery cell 1 is directly treated as unqualified.

[0090] In addition, considering that helium has a certain adhesion, the helium inspection assembly is usually made of non-metallic materials. Once impurities such as dust are mixed into the assembly (during the positive pressure helium inspection process), it is difficult to completely remove the helium. In the case of the first leak point, a large amount of helium is suddenly injected, and it is difficult for the negative pressure system to completely remove the residual helium. It can be seen that if the prior art fails to stop injecting helium into the battery cell 1 when the first leak point is found, the above-mentioned adverse consequences will occur. This will not only interfere with the assembly and inspection of other battery cells 1 by the assembly cavity 2, but also cause damage to the assembly cavity 2.

[0091] S301, the assembly chamber 2 is evacuated for the second time by the first vacuum pump 23, and the battery cell 1 is evacuated for the first time by the second vacuum pump 13; this parallel operation is intended to simultaneously reduce the air pressure inside the assembly chamber 2 and the battery cell 1, so as to prepare for the subsequent helium injection and detection. Through the double vacuum treatment, possible air or impurities can be removed more effectively, and the accuracy of the detection can be improved.

[0092] S401, the helium cylinder 4 injects helium into the liquid injection port of the battery cell 1 through the second pipe 11;

[0093] During the helium injection stage, based on the change in the value of the first vacuum gauge 22, it is determined whether the battery cell 1 has a second leak. If no second leak occurs, proceed to the next step.

[0094] In the above technical solution, the second leak point refers to other leak points whose leakage is less than that of the first leak point, but its leakage assessment standard is still higher than that of the prior art. In this application, it has been fully considered that whether before or during the injection of helium, as long as the leakage of the battery cell (leakage rate in the specific implementation process) reaches a certain threshold, helium will leak into the assembly cavity 2. If the concentration of helium accumulated in the assembly cavity 2 is high, when using the helium mass spectrometer (helium detector 3) of the prior art for detection, some of the helium with excessive concentration may contact the helium detector 3, thereby contaminating the detection equipment and causing it to make a permanent wrong judgment.

[0095] Therefore, the present application sets two testing standards to avoid the above situation. If the battery cell 1 is detected to have a second leak point, the subsequent step of passing the helium detector 3 is notified, and the battery cell 1 is directly treated as unqualified.

[0096] S501, the first vacuum pump 23 evacuates the assembly chamber 2 for the third time, and after the assembly chamber 2 reaches a predetermined pressure value, the first vacuum pump 23 is turned off, and the helium detector 3 collects the helium leak rate;

[0097] Determine whether the third leak point exists in the battery cell 1 according to the helium leak detection rate;

[0098] Among them, the assembly chamber 2 is evacuated for the third time again until the predetermined air pressure value is reached and then the first vacuum pump 23 is turned off. At this time, the air pressure in the assembly chamber 2 has dropped to an extremely low level, providing ideal conditions for accurate detection by the helium detector 3. Subsequently, the helium detector 3 is started to sample and analyze the gas in the assembly chamber 2 to detect whether there is a helium component and calculate the leakage rate data. By comparing these data with the pre-set standard values, it can be determined whether the battery cell 1 has a third leakage point, that is, a micro-leakage phenomenon. If the test result shows that the leakage rate is lower than the standard value, it is considered that the sealing performance of the battery cell 1 is qualified; otherwise, the battery cell 1 is treated as unqualified.

[0099] S601 , after restoring the air pressure in the battery cell 1 and the assembly chamber 2 , taking out the battery cell 1 .

[0100] In summary, the present application sets the first, second and third leakage points and uses the air pressure detection method to detect the first and second leakage points, thereby effectively avoiding the problem of insufficient control of obvious leakage points in the prior art, thereby preventing the waste and damage of helium detection resources.

[0101] The other details that are the same as those in Example 1 are not described in detail in this example.

[0102] Example 3

[0103] like Figure 1-2 As shown, the difference from Example 1 is that: in order to further clarify the detection method of the first leakage point of the present application, specifically, the method for determining the first leakage point in step S201 further includes the following steps:

[0104] S202, obtaining the value A of the second vacuum gauge 12 in step S101 1 Before evacuating the assembly chamber 2 to 40 Pa in step S201, obtain the value A of the second vacuum gauge 12 2 , if A 1 -A 2 ≤A 0 , it is determined that the first leakage point appears in battery cell 1.

[0105] Among them, the present application takes into account that the prior art often directly evacuates the chamber before assembly to the vacuum value before helium injection, and this method directly ignores the pressure change of the battery cell 1 in the assembly chamber 2. In the specific implementation process, the present application records and compares the change of the vacuum count value when the pressure in the assembly chamber 2 is evacuated to a value within 20000Pa by the first vacuum pump 23, where 40Pa is the limit value for the second vacuuming of the assembly chamber 2, and it is not necessary to detect when it is close to 40Pa.

[0106] Further, in step S302, A 0 The value range of A0 is 10000-16000, in Pa. Among them, when the optimal reference value of A0 is 15000, however, in the specific implementation process, the adjustment of A0 in this application is not limited to the above optimal value and reference range, but also depends on the specific actual situation. Specifically, if the value A0 of the second vacuum gauge 12 is 1 -10000Pa≤15000Pa (in view of the fact that before the assembly chamber 2 is evacuated to 40Pa, the second vacuum gauge 12 should ideally be maintained at standard atmospheric pressure, but certain deviations may occur during the technical implementation process. Therefore, A in this application 0 The above situation has been fully considered in the value, and a wider value range is set accordingly. ), then it is determined that the first leak point has appeared.

[0107] The other details that are the same as those in Example 1 are not described in detail in this example.

[0108] Example 4

[0109] like Figure 1-2 As shown, the difference from Example 1 is that: in order to further reflect the method of determining the second leakage point of the present application, specifically, the method of determining the second leakage point in step S401 is further:

[0110] S402, before the helium injection stage, obtain the value B of the first vacuum gauge 22 1 During the helium injection stage, the value B of the first vacuum gauge 22 is 2 , if B 2 -B 1 ≥B 0 , it is determined that the second leakage point appears in battery cell 1.

[0111] Its working principle is based on the consideration of the air pressure in the assembly chamber 2, which has been extracted to a lower level in step S301. During the process of positive pressure helium injection into the battery cell 1, if the battery cell 1 has a second leak (i.e., a tiny leak that was not found in the first leak detection), part of the helium will leak into the assembly chamber 2, thereby causing an increase in the air pressure in the assembly chamber 2. By detecting the increase in the air pressure in the chamber before assembly, it can be determined whether the second leak has occurred.

[0112] In step S402, B 0 The value range is set to 40-120, the unit is Pa. In the specific implementation process, B 0 The optimal value of is 100, which is applicable to the detection of the second leakage point of most batteries. 0 The adjustment of B is not limited to the above optimal value and reference range, but also depends on the actual situation. 1 The value of B is set to 40Pa. 1 The value of represents the pressure value of the second vacuum pumping of the assembly chamber 2, and B 0 The above values ​​are the best choice under ideal conditions. These values ​​can be directly used in actual testing, and the second leak point can be flexibly determined according to the actual situation.

[0113] Other details that are the same as those in Example 1 are not described in detail in this application.

[0114] Example 5

[0115] like Figure 1-2 As shown, the difference from Example 1 is that: in order to further improve the efficiency and stability of the positive pressure helium detection method of the present application, specifically, the method for determining the third leak point in step S501 is:

[0116] S502, during a collection cycle of the helium detector 3, the collected leakage rate is compared with the third leakage point judgment value; if the collected leakage rate is greater than the third leakage point judgment value, it is determined that the battery cell 1 has a third leakage point;

[0117] Among them, the acquisition time of one acquisition cycle of helium detector 3 is 5S; the third leakage point judgment value is 5*10 -7 , its unit is Pa*m 3 / s.

[0118] Furthermore, the predetermined air pressure value in step S501 is any value between 40 and 4, and the unit is Pa. The implementation reason of the above technical means is that the lower the vacuum value of the assembly, the more accurate the final helium detection result is. If the vacuum value is too low, it will cause the battery cell 1 with the third leakage point to pass a large amount of helium into the helium detector 3 under the action of the predetermined air pressure when the helium detector starts to collect, thereby damaging the helium detector 3. It also has a protective effect on the helium detector 3. When the predetermined air pressure value is less than 40 and greater than 4, it can ensure a certain detection accuracy while avoiding damage to the helium detector 3.

[0119] Furthermore, in order to improve the detection efficiency, step S601 also includes the following steps:

[0120] S602, extracting a second set value of helium from the battery cell 1; wherein the second set value is a helium clearing pressure value, specifically 25000 Pa;

[0121] S603, the assembly is pressurized to the assembly vacuum breaking setting value, and the battery cell 1 is pressurized to the battery cell 1 vacuum breaking pressure; the assembly vacuum breaking setting value and the battery cell 1 vacuum breaking pressure setting value are both any value between 90000Pa and 100000Pa. In a specific implementation, considering that the battery cell 1 can be taken out when the pressure values ​​of both the assembly and the battery cell 1 do not reach 100000Pa, the present application further sets the assembly vacuum breaking setting value and the battery cell 1 vacuum breaking pressure setting value to 90000Pa, thereby improving the detection efficiency.

[0122] The rest of the details are the same as those in Implementation 1 and will not be described in detail in this embodiment.

[0123] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A positive pressure helium inspection device, comprising an assembly chamber (2) for assembling a battery cell (1), characterized in that: The assembly chamber (2) is connected to the helium detector (3) via a first pipe (21), and the first pipe (21) is equipped with a first vacuum gauge (22) for measuring the internal air pressure of the assembly chamber (2) and a first vacuum pump (23) for extracting air from the assembly chamber (2); The battery cell (1) is connected to a helium cylinder (4) via a second pipe (11), and the second pipe (11) is equipped with a second vacuum gauge (12) for measuring the internal air pressure of the battery cell (1) and a second vacuum pump (13) for extracting air from the battery cell (1).

2. The positive pressure helium detection device according to claim 1, characterized in that: The first pipeline (21) is equipped with a first valve (211), and the first valve (211) is used to control the communication between the helium detector (3) and the assembly chamber (2); The second pipeline (11) is equipped with a second valve (111), and the second valve (111) is used to control the communication between the helium bottle (4) and the battery cell (1).

3. The positive pressure helium detection device according to claim 2, characterized in that: The first vacuum pump (23) is connected to the first pipeline (21) through a first branch pipe (212), and the first branch pipe (212) is equipped with a third valve (231); The second vacuum pump (13) is connected to the second pipeline (11) via a second branch pipe (112), and the second branch pipe (112) is equipped with a second valve (131).

4. A positive pressure helium detection method, characterized in that: Using the positive pressure helium detection device as described in any one of claims 1 to 3, the detection steps are as follows: S101, assembling the battery cell (1) in the assembly cavity (2), and sealing the assembly cavity (2); S201, evacuating the assembly chamber (2) for the first time by using a first vacuum pump (23); judging whether a first leak point appears in the battery cell (1) based on a change in the value of a second vacuum gauge (12); and proceeding to the next step if no first leak point appears; S301, performing a second vacuum pumping on the assembly chamber (2) by using a first vacuum pump (23), and performing a first vacuum pumping on the battery cell (1) by using a second vacuum pump (13); S401, a helium bottle (4) injects helium into the liquid injection port of the battery cell (1) through a second pipe (11); During the helium injection stage, judging whether the battery cell (1) has a second leak point based on the change in the value of the first vacuum gauge (22), and proceeding to the next step if no second leak point has occurred; S501, the first vacuum pump (23) performs a third vacuum pumping on the assembly chamber (2), and after the assembly chamber (2) reaches a predetermined pressure value, the first vacuum pump (23) is turned off, and the helium detector (3) collects the helium leak rate; Judging whether a third leak point occurs in the battery cell (1) according to the helium leak detection rate; S601, after restoring the air pressure in the battery cell (1) and the assembly chamber (2), taking out the battery cell (1).

5. The positive pressure helium detection method according to claim 4, characterized in that: The method for determining the first leak point in step S201 is: S202, obtaining the value A1 of the second vacuum gauge (12) in step S101, and obtaining the value A2 of the second vacuum gauge (12) before evacuating the assembly chamber (2) to 40 Pa in step S201, and if A1-A2≤A0, determining that the battery cell (1) has a first leak point.

6. The positive pressure helium detection method according to claim 5, characterized in that: In step S302, the value range of A0 is 10000-16000, and the unit is Pa.

7. The positive pressure helium detection method according to claim 4, characterized in that: The method for determining the second leakage point in step S401 is: S402, before the helium injection stage, obtaining the value B1 of the first vacuum gauge (22); during the helium injection stage, obtaining the value B2 of the first vacuum gauge (22); if B2-B1≥B0, it is determined that a second leak point occurs in the battery cell (1).

8. The positive pressure helium detection method according to claim 7, characterized in that: In step S402, the value range of B0 is 120-40, and the value of B1 is 40, both in units of Pa.

9. The positive pressure helium detection method according to claim 4, characterized in that: The predetermined air pressure value in step S501 is any value between 4 and 40, in units of Pa.

10. The positive pressure helium detection method according to claim 4, characterized in that: The method for determining the third leakage point in step S501 is: S502, during a collection cycle of the helium detector (3), comparing the collected leakage rate with the third leakage point judgment value; if the collected leakage rate is greater than the third leakage point judgment value, determining that the battery cell (1) has a third leakage point; The acquisition time of one acquisition cycle of the helium detector (3) is 3-5 seconds; the third leakage point judgment value is 5*10 -7 , unit is Pa*m 3 / s.

Images