Square battery sealing detection structure and detection method

Abstract

This invention belongs to the field of battery sealing test technology, and discloses a square battery sealing test structure and test method. The battery includes a cover plate, and a sealing sheet and a sealing plug are connected to the cover plate from top to bottom, forming a cavity between the sealing sheet and the sealing plug. The test structure includes an air bag inside the cavity, containing the gas to be tested. The air bag is made of heat-resistant material and includes an air bag opening and an air bag body, which are connected by a narrow neck channel. The sealing sheet is made of paramagnetic metal, and the air bag body covers the sealing plug. The narrow neck channel is on one side of the sealing plug, and a first magnet is placed above the narrow neck channel. The first magnet is attracted to the cover plate, sealing the narrow neck channel. After the sealing sheet is welded and cooled, a third magnet is placed on the sealing sheet. The third magnet drives the first magnet to separate from the cover plate, opening the narrow neck channel and releasing the gas. This invention ensures the integrity of the air bag during welding and releases the gas to be tested after welding, thus ensuring reliable and accurate test results.

Description

Technical Field

[0001] This invention belongs to the field of battery sealing test technology, specifically relating to a square battery sealing test structure and test method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In the manufacturing process of lithium batteries, the aluminum shell and cover plate are usually welded together. Currently, the industry typically uses helium detection to check the welding effect and ensure the overall sealing performance of the cell.

[0004] Existing technology discloses a method for airtight testing of a square lithium battery. The square lithium battery body has an injection hole and an injection port communicating with the injection hole. The injection hole is sealed with a sealing plug, and a gas bag containing detection gas is placed on top of the sealing plug. A welding piece is welded to the injection port for sealing. During welding, the gas bag melts and ruptures, releasing the detection gas between the sealing plug and the welding piece.

[0005] The above solution has the following drawbacks: The gas bag is placed on the sealing plug under the welding patch. When welding the welding patch, the welding heat may cause the gas bag to melt and burst prematurely. After welding, the gas has been released, resulting in detection failure. Alternatively, if the gas bag does not melt and burst after welding, the detection will also fail. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a square battery sealing detection structure and detection method, which can solve the technical problem in the prior art that when the welding heat is used to melt the gas bag to release the detection gas and detect the welding sealing effect, the welding heat causes the gas bag to melt prematurely or the gas bag does not melt, resulting in detection failure.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a square battery sealing detection structure is provided. The battery includes a cover plate, and a sealing sheet and a sealing plug are connected from top to bottom on the cover plate. A cavity is formed between the sealing sheet and the sealing plug. The detection structure includes an air bag placed in the cavity, and the air bag contains the gas to be tested. The air bag is made of heat-resistant material and includes an air bag opening and an air bag body. The air bag opening and the air bag body are connected by a narrow neck channel. The sealing sheet is made of paramagnetic metal. The gas bag body covers the sealing plug. The narrow neck channel is on one side of the sealing plug. A first magnet is placed above the narrow neck channel. The first magnet is attracted to the cover plate on the bottom of the cavity to seal the narrow neck channel. After the sealing sheet is welded and cooled, a third magnet is placed on the sealing sheet. The third magnet drives the first magnet to separate from the cover plate, and the narrow neck channel opens to release gas.

[0008] Preferably, a second magnet is placed on the other side of the sealing plug. The second magnet is also attracted to the cover plate at the bottom of the cavity, and the top surface of the second magnet is in contact with the bottom surface of the air bag body. The third magnet synchronously drives the first magnet and the second magnet to separate from the cover plate. The second magnet squeezes the air bag body to accelerate the release of gas.

[0009] Preferably, the third magnet is a strong magnet, and the sealing sheet is an aluminum sealing sheet.

[0010] Preferably, the air bag opening is a round hard plastic ring, and an inflation tube is inserted into the air bag opening.

[0011] Preferably, the heat-resistant material is silicone rubber, fluororubber, or perfluoroether rubber, which can withstand the heat radiation from welding the sealing sheet without melting or breaking.

[0012] Preferably, a first magnet groove and a second magnet groove are formed on the cover plate at the bottom of the cavity.

[0013] Secondly, a method for testing the airtightness of the aforementioned square battery sealing test structure is provided, the specific steps of which include: First, insert the sealing plug into the injection hole of the cover plate; Then place the second magnet in the second magnet slot, and place the air bag on top of the sealing plug so that the air bag body covers the sealing plug; Then, a quantitative amount of the gas to be tested is injected into the gas bag, and then the first magnet is placed above the narrow neck channel, and the first magnet is inserted into the first magnet slot; Then, the sealing sheet is welded to the liquid injection port of the cover plate, and after the welding cools, a third magnet is placed on top of the sealing sheet; Next, it is checked whether the gas being tested escapes from the weld of the sealing sheet.

[0014] Preferably, after placing the second magnet, the inflation tube opening is inserted into the circular hard plastic ring opening. First, negative pressure is used to fix the inflation tube opening and the circular hard plastic ring opening, and then the air bag is moved and placed above the sealing plug.

[0015] Preferably, after the third magnet is placed, the magnetic force of the third magnet drives the first magnet upward to disengage from the narrow neck channel, while simultaneously driving the second magnet upward to squeeze the air bag body, so that the gas to be tested is fully released and fills the cavity.

[0016] Preferably, the gas to be tested is helium, and a helium mass spectrometer leak detector is used to detect the weld.

[0017] Compared with the prior art, the advantages and positive effects of this invention are: This invention places a heat-resistant gas bag within the cavity between a sealing sheet and a sealing plug. The gas bag includes a gas bag opening and a gas bag body, with a narrow neck channel connecting the gas bag body and the gas bag opening. After the gas to be tested is injected into the gas bag body, a first magnet is placed on the narrow neck channel. The first magnet is attracted to a cover plate on one side of the sealing plug, sealing the narrow neck channel. After the sealing sheet is welded, a third magnet is placed above the sealing sheet. The third magnet separates the first magnet from the cover plate, thereby opening the narrow neck channel and releasing the gas to be tested. This invention ensures the integrity of the gas bag during the welding process, preventing premature release of the gas to be tested due to gas bag rupture. It also allows the gas bag to open the narrow neck channel and release the gas to be tested after welding is completed, thus achieving reliable and accurate sealing detection of the weld seam of the sealing sheet. This invention has the technical effect of ensuring reliable and accurate test results. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a cross-sectional view of a square battery sealing detection structure according to Embodiment 1 or Embodiment 2 of the present invention; In the picture: 1. Cover plate; 2. Sealing plug; 3. Sealing sheet; 4. Air bag body; 5. Air bag opening; 6. Narrow neck channel; 7. First magnet; 8. Second magnet; 9. Third magnet. Detailed Implementation

[0020] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] The present invention will now be described in detail with reference to the accompanying drawings.

[0022] Example 1 This embodiment discloses a square battery sealing detection structure, such as Figure 1As shown, the battery includes a cover plate 1 on the battery body, with an injection port and an injection hole from top to bottom. A sealing plug 2 is inserted into the injection hole after the battery cell is injected with electrolyte to seal it. After sealing the injection hole, a sealing sheet 3 is welded onto the injection port to achieve a seal. A gas bag containing the gas to be tested is placed in the cavity between the sealing plug 2 and the sealing sheet 3. The gas bag is made of heat-resistant material and will not break during the welding process of the sealing sheet 3. It is understood that if the gas bag breaks during the welding process when the sealing sheet 3 is welded to the injection port, the gas to be tested will be released prematurely during welding, affecting the accuracy of the sealing test result after the sealing sheet 3 is welded. Therefore, in this embodiment, the gas bag is made of heat-resistant material and will not break during welding, ensuring that the gas to be tested does not leak after the welding of the sealing sheet 3 is completed.

[0023] like Figure 1 As shown, because the injection port is welded with a sealing plate 3 and the injection hole is plugged with a sealing plug 2, a sealed cavity is formed between the sealing plate 3 and the sealing plug 2. The gas bag does not release the gas being tested, and therefore, a seal test cannot be achieved. Therefore, as... Figure 1 As shown, the airbag in this embodiment includes an airbag opening 5 and an airbag body 4, which are connected by a narrow neck channel 6. The airbag body 4 covers the sealing plug 2, and the narrow neck channel 6 is located on one side of the sealing plug 2. A first magnet 7 is placed above the narrow neck channel 6, and the bottom surface of the first magnet 7 is attracted to the cover plate 1 on the bottom surface of the cavity, thus sealing the narrow neck channel 6. It should be noted that in this embodiment, the cover plate 1 is made of iron, thereby ensuring that the first magnet 7 can be attracted to the cover plate 1 on the bottom surface of the cavity, thus sealing the narrow neck channel 6.

[0024] Understandably, the two ends of the narrow neck channel 6 are connected to the air bag body 4 and the air bag opening 5, respectively. The gas to be tested is filled into the air bag body 4 through the air bag opening 5. After the air bag body 4 is filled with the gas to be tested, the end of the narrow neck channel 6 near the air bag body 4 is pinched to disconnect the air filling pipe of the air bag opening 5. The first magnet 7 is pressed on the narrow neck channel 6. The bottom surface of the first magnet 7 is attracted to the cover plate 1 on the bottom surface of the cavity, which compresses or blocks the narrow neck channel 6, thereby sealing the air bag body 4 and preventing the gas to be tested from leaking out of the air bag body 4.

[0025] like Figure 1As shown, a third magnet 9 is placed on the sealing sheet 3. The third magnet 9 drives the first magnet 7 to separate from the cover plate 1, opening the narrow neck channel 6 and releasing the gas to be tested to fill the cavity between the sealing sheet 3 and the sealing plug 2. It should be noted that the sealing sheet 3 is made of paramagnetic metal. When the third magnet 9 is placed on the sealing sheet 3, the paramagnetic metal cannot block the magnetism of the third magnet 9. The magnetism of the third magnet 9 is greater than that of the first magnet 7, and the third magnet 9 generates sufficient attraction to the first magnet 7. The third magnet 9 attracts the first magnet 7 upwards, and the narrow neck channel 6 is no longer compressed. The gas to be tested in the gas bag body 4 is released from the narrow neck channel 6, filling the cavity between the sealing sheet 3 and the sealing plug 2. At this time, the gas to be tested is detected at the weld of the sealing sheet 3 to determine whether the weld is leaking, thus judging the sealing effect of the weld. If the gas to be tested is detected to escape, it indicates that there is a leak in the weld, and the battery is judged as a defective product. Conversely, if the gas is not leaking, it indicates that the seal is good. In this way, accurate and reliable testing of the battery sealing performance is achieved after welding.

[0026] It should also be noted that in this embodiment, the air bag body 4 is elastic. When it is inflated, the gas being tested will support the air bag body 4, and the magnetic attraction between the first magnet 7 and the cover plate 1 is greater than the gas pressure inside the air bag body 4.

[0027] It should be noted that, unlike existing technologies where the gas ruptures prematurely during welding or cannot be punctured after welding, the gas bag in this embodiment is made of heat-resistant material, ensuring it can withstand the high temperatures during welding without melting. This embodiment also provides a controllable release mechanism. A narrow neck channel 6 is designed between the gas bag opening 5 and the gas bag body 4, and a first magnet 7 is placed above the narrow neck channel 6. The first magnet 7 is attracted to the cover plate 1, firmly sealing the narrow neck channel 6 during welding, thereby completely isolating the gas to be tested inside the gas bag body 4. After the sealing sheet 3 cools after welding, a third magnet 9 is placed on the sealing sheet 3, using magnetic force to drive the first magnet 7 to separate from the cover plate 1, thereby opening the narrow neck channel 6 and achieving precise release of the gas to be tested. This magnetically driven release method avoids physical damage to the gas bag, ensures the stability of the release process, and improves the accuracy and reliability of the square battery sealing test.

[0028] In this embodiment, the square battery sealing detection structure uses a third magnet 9 to drive the first magnet 7 to separate from the cover plate 1, opening the narrow neck channel 6 to release the gas to be tested inside the gas bag body 4. However, relying solely on the opening of the narrow neck channel 6 may result in a slow gas release rate from the gas bag body 4, affecting detection efficiency. To address this, in this embodiment, a second magnet 8 is placed below the gas bag body 4 on the other side of the sealing plug 2, and the second magnet 8 is also adsorbed onto the cover plate 1 at the bottom of the cavity. The third magnet 9 is placed on the sealing sheet 3. The third magnet 9 not only drives the first magnet 7 to separate from the cover plate 1, opening the narrow neck channel 6, but also simultaneously drives the first magnet 7 and the second magnet 8 to separate from the cover plate 1. The second magnet 8 generates an upward force, squeezing the gas to be tested inside the gas bag body 4 to accelerate its release. It should be noted that the area of ​​the third magnet 9 is smaller than the area of ​​the sealing sheet 3, and the third magnet 9 covers the first magnet 7 and the second magnet 8, meaning that the area of ​​the third magnet 9 is larger than the areas of the first magnet 7 and the second magnet 8.

[0029] Understandably, the top surface of the second magnet 8 contacts the bottom surface of the air bag body 4. After the third magnet 9 synchronously drives the first magnet 7 and the second magnet 8 to separate from the cover plate 1, the first magnet 7 quickly adheres upward to the bottom surface of the sealing sheet 3. At this time, the narrow neck channel 6 is opened, and the gas to be tested in the air bag body 4 begins to be released. The top surface of the second magnet 8 contacts the bottom surface of the air bag body 4, and at the same time, the second magnet 8 continues to squeeze the air bag body 4 upward, accelerating the release of the gas to be tested in the air bag body 4.

[0030] Understandably, the release of the tested gas does not solely rely on the opening of the narrow neck channel 6, but rather on the active compression of the gas bag body 4 by the second magnet 8. This ensures that the tested gas can be released from the gas bag more quickly and thoroughly, thus providing a sufficient and stable gas sample for subsequent sealing tests. This active compression mechanism significantly accelerates the release speed of the tested gas and ensures that the gas inside the gas bag body can be more fully discharged, avoiding gas residue and improving the efficiency and integrity of gas release. This is crucial for the subsequent sealing test stage, providing the testing equipment with a more stable and sufficient tested gas, thereby improving the accuracy and reliability of the entire sealing test process.

[0031] The first magnet 7 and the second magnet 8 are separated from the cover plate 1 by the third magnet 9, thereby opening the narrow neck channel 6 and squeezing the gas bag body 4, thus accelerating the release of the gas being tested. However, in actual operation, if the magnetic drive effect is not good, the first magnet 7 and the second magnet 8 may not be able to effectively separate or squeeze the gas bag body, thus affecting the full release of the gas being tested, and thus reducing the efficiency and accuracy of the seal detection.

[0032] To address this, this embodiment further proposes that the third magnet 9 be a strong magnet, and the sealing sheet 3 be an aluminum sealing sheet. The strong magnet refers to a permanent magnet material with high remanence, high coercivity, and high energy product, capable of generating a powerful magnetic field. Using a strong magnet as the third magnet provides a sufficiently strong magnetic force to reliably drive the first magnet 7 and the second magnet 8 to separate from the cover plate 1. This overcomes the attraction between the first and second magnets and the cover plate, as well as the resistance of the airbag body to the second magnet. In one specific embodiment, the strong magnet is a neodymium iron boron magnet, which has a high energy product and can provide strong attraction and driving force.

[0033] An aluminum sealing strip is a thin sheet made of aluminum or aluminum alloy used to seal the injection port. Aluminum is a non-magnetic or weakly magnetic material. The main function of using an aluminum sealing strip is to prevent the sealing strip from interfering with the magnetic force of the third magnet. Because aluminum is a non-magnetic material, when the third magnet is placed above the sealing strip, its magnetic force can act unimpeded on the first magnet 7 and the second magnet 8 below the cover plate 1, ensuring the effectiveness of magnetic actuation. Furthermore, aluminum has good thermal conductivity and weldability, facilitating welded sealing.

[0034] In this embodiment, the square battery sealing detection structure injects the gas to be tested into the air bag body 4 through the air bag opening 5. In order to enhance the matching between the air bag opening and the inflation pipe opening, and to ensure the connection between the inflation pipe opening and the air bag opening 5 is stable and to ensure inflation efficiency, the air bag opening 5 in this embodiment adopts a circular hard plastic ring opening.

[0035] The circular hard plastic ring refers to the circular, rigid plastic ring structure of the air bag opening 5. This structure provides the necessary mechanical strength and shape stability for the air bag opening 5, making it less prone to deformation or damage during connection and operation. The air bag opening 5 is matched with the inflation pipe opening; that is, the design dimensions and structural features of the circular hard plastic ring opening can form a tight and reliable connection with the external inflation pipe opening. This ensures that when the gas to be tested is injected into the air bag body 4, the inflation pipe opening can be firmly inserted into or connected to the circular hard plastic ring opening, forming an effective seal to prevent gas leakage. Matching methods include, but are not limited to: the inner diameter of the circular hard plastic ring opening forming an interference fit or clearance fit with the outer diameter of the inflation pipe opening, and achieving sealing through auxiliary structures such as O-rings and conical seals.

[0036] In this embodiment, the gas bag opening 5 is a circular hard plastic ring opening, and the inner wall of the gas bag opening 5 is designed with an annular groove to accommodate the O-ring seal. The inflation pipe opening is a connector with a corresponding outer diameter and flange. The front end of the inflation pipe opening is designed to be tapered or chamfered to facilitate insertion. When the inflation pipe opening is inserted into the circular hard plastic ring opening, the O-ring seal is compressed, forming a sealing barrier between the two, preventing the loss of the tested gas during the injection process, and ensuring the purity and quantitative accuracy of the injected gas. This not only improves the efficiency of gas injection and the convenience of operation, but more importantly, it provides an accurate and reliable source of the tested gas for subsequent sealing tests, improving the detection accuracy and reliability of the entire square battery sealing test structure.

[0037] In this embodiment, the gas bag is made of a heat-resistant material, such as silicone rubber, fluororubber, or perfluoroether rubber. The gas bag can withstand the heat radiation from welding the sealing sheet 3 without melting or bursting. In the square battery sealing detection structure of this embodiment, the gas bag is placed above the sealing plug 2, close to the sealing sheet 3 that is about to be welded. During welding, the four sides of the sealing sheet 3 will generate local high temperatures and heat radiation. The heat radiation will be conducted towards the center of the sealing sheet 3 and then act on the gas bag body 4. If the heat resistance of the gas bag material is insufficient, the gas bag body 4 may melt and burst, causing the tested gas to be released prematurely, thus affecting the accuracy of the airtightness test.

[0038] The gas bag body 4, made of silicone rubber, fluororubber, or perfluoroether rubber, can effectively resist the heat radiation generated during the welding process and will not melt or burst under short-term high-temperature environments. This ensures that the gas bag body 4 can completely store the gas being tested, providing a reliable sample for subsequent sealing tests, thereby ensuring the accuracy and reliability of the entire testing process.

[0039] In this embodiment, the diameter of the injection port is larger than the diameter of the injection hole, and a first magnet groove and a second magnet groove are formed at the bottom of the injection port. The larger diameter of the injection port provides more spacious installation space for the air bag, the first magnet 7, and the second magnet 8. The first magnet groove and the second magnet groove at the bottom of the injection port ensure that the first magnet and the second magnet are precisely placed in their predetermined positions during installation, preventing displacement of the first magnet and the second magnet during subsequent operations.

[0040] It is understandable that the first magnet slot and the second magnet slot match the shape of the first magnet and the second magnet.

[0041] Example 2 This embodiment discloses an airtightness testing method for a square battery sealing testing structure, which utilizes a square battery sealing testing structure disclosed in Embodiment 1. The specific steps include: S1. Insert the sealing plug 2 into the injection hole of the cover plate 1 to complete the sealing of the injection hole; S2. Place the second magnet 8 in the second magnet groove, place the air bag above the sealing plug 2, so that the air bag body 4 covers the sealing plug 2, and place the narrow neck channel 6 on one side of the first magnet groove. S3. A quantitative amount of gas to be tested is injected into the air bag body 4 through the air bag opening 5. Then, the first magnet 7 is placed above the narrow neck channel 6 and the first magnet is inserted into the first magnet slot. S4. Weld the sealing sheet 3 to the liquid injection port of the cover plate 1 to complete the liquid injection port weld; after the sealing sheet 3 has cooled down, place the third magnet 9 on top of the sealing sheet 3. S5. Check whether the gas being tested escapes from the weld of the sealing sheet 3.

[0042] Step S1 in this embodiment aims to ensure that the injection hole of the cover plate 1 is sealed before the airtightness test. The sealing plug 2 is inserted into the injection hole by mechanical pressing. Its function is to physically block the injection hole and prevent the subsequently injected gas to be tested from leaking from there, thus providing a closed testing environment for the gas in the gas bag.

[0043] Step S2 of this embodiment involves the initial positioning of the gas bag and the second magnet 8. The placement of the second magnet is to compress the gas bag body 4 in subsequent steps, assisting in the rapid release of the gas to be tested. Step S3 of this embodiment is the core preparation step for airtightness testing. Injecting a quantitative amount of the gas to be tested ensures the standardization of the test. The gas to be tested can be an easily detectable tracer gas such as helium or hydrogen. The first magnet 7 is placed in the first magnet slot to use magnetic force to seal the narrow neck channel 6, thereby temporarily storing the injected gas to be tested in the gas bag body 4, preventing premature release, and providing a stable internal environment for subsequent sealing plate welding.

[0044] Step S4 in this embodiment completes the final sealing of the battery filling port, which is a crucial step in the battery production process. Laser welding is used for the sealing sheet to ensure the tightness of the weld. After the weld cools, the third magnet 9 is placed, and the magnetic force of the third magnet 9 drives the first magnet 7 and the second magnet 8 to separate from the cover plate 1, thereby opening the narrow neck channel 6 and squeezing the gas bag body 4 to quickly release the gas being tested.

[0045] Step S5 in this embodiment is the final judgment stage of the airtightness test. Using specialized testing equipment, such as a mass spectrometer leak detector, the weld area of ​​the sealing strip is inspected to determine if there is any leakage of the tested gas. The detection results of the escaping gas directly reflect the quality of the sealing strip weld, thereby evaluating the battery's sealing performance.

[0046] The airtightness testing method in this embodiment achieves accurate evaluation of the sealing performance of square batteries through steps S1-S5. The entire method is rigorous, ensuring the accuracy and efficiency of the test, and effectively solving the problem of inaccurate test results caused by untimely or insufficient gas release in traditional testing methods.

[0047] In step S2 of this embodiment, before placing the gas bag above the sealing plug 2, the inflation pipe opening is first inserted into the circular hard plastic ring opening (gas bag opening 5). Then, negative pressure is applied to create a tight suction fixation between the inflation pipe opening and the gas bag opening 5. The gas bag is then moved and placed above the sealing plug 2. It can be understood that the inflation pipe opening is the interface used to connect the external gas source to the gas bag opening 5, and its function is to accurately deliver a quantitative amount of the gas to be tested into the gas bag. Applying negative pressure after connecting the inflation pipe opening and the gas bag opening 5 allows for early observation to check for any damage to the gas bag, preventing subsequent steps where leakage is discovered after inflation and the first magnet 7 is placed, necessitating replacement.

[0048] In step S4 of this embodiment, the magnetic force of the third magnet 9 drives the first magnet 7 to move upward away from the narrow neck channel 6, while simultaneously driving the second magnet 8 to squeeze the air bag body 4 upward. When the air bag body 4 is squeezed, it accelerates the release of the gas being tested and quickly fills the cavity between the sealing plug 2 and the sealing sheet 3.

[0049] Understandably, the third magnet 9 is a strong magnet, and the sealing plate 3 is an aluminum sealing plate. The magnetic force of the third magnet 9 is greater than the attraction force between the first magnet 7, the second magnet 8, and the cover plate 1, and also greater than the resistance of the air bag body 4 to the second magnet 8. The third magnet 9 is placed above the sealing plate 3, allowing the first magnet 7 and the second magnet 8 to overcome the attraction force between themselves and the cover plate 1, and to overcome the resistance of the air bag body 4 to the second magnet 8, causing the first magnet 7 and the second magnet 8 to move upwards simultaneously. The first magnet 7 moves upwards away from the narrow neck channel 6, thereby opening the gas flow path between the air bag body 4 and the air bag opening 5. At the same time, the second magnet 8 moves upwards and applies pressure to the air bag body 4. Under the pressure of the second magnet, the gas to be tested inside the air bag body 4 is actively and quickly discharged from the air bag body 4. The discharged gas passes through the opened narrow neck channel 6 and fully enters the sealed cavity formed between the sealing plate 3 and the sealing plug 2, providing sufficient gas for subsequent leak detection steps.

[0050] It is also understandable that this synchronous driving and active compression mechanism ensures that the gas to be tested within the gas bag body can be released quickly and fully, effectively filling the cavity to be tested. This effectively solves the problem of insufficient or untimely gas release caused by relying solely on passive diffusion or natural contraction, ensuring the efficiency and accuracy of the leak detection process and avoiding detection errors or missed detections due to insufficient gas release, thereby improving the accuracy and reliability of the entire airtightness testing process. Simultaneously, the active compression method also shortens the time required for gas release, further improving overall detection efficiency.

[0051] In this embodiment, a helium mass spectrometer leak detector is used for detection. The gas being detected is helium with a purity of not less than 99.9999%, and the detection accuracy can identify weld leaks of ≤0.01mm.

[0052] It should be noted that the gas being tested is helium. Helium, as an inert gas, possesses advantages such as small molecular diameter, high permeability, chemical stability, non-toxicity, and non-flammability. As a tracer gas, it can penetrate extremely small leaks and will not chemically react with the tested product, thus ensuring the safety and accuracy of the testing process. Besides helium, hydrogen can also be considered as a tracer gas, but hydrogen is flammable and, in certain applications, is less safe than helium.

[0053] Helium mass spectrometry leak detectors utilize highly sensitive mass spectrometry technology to detect the presence of helium ions in the gas at the weld joint. Because helium molecules are small in diameter and highly permeable, high-purity helium gas will escape through even tiny leaks in the weld joint of sealing sheet 3. Helium mass spectrometry leak detectors, with their extremely high sensitivity and specific recognition ability for helium molecules, can quickly capture the trace amounts of escaping helium gas and distinguish them from the background gas, thereby accurately determining whether a leak exists at the weld joint and the size of the leak.

[0054] In this implementation, a helium purity of no less than 99.9999% means that the helium content in the helium sample reaches an extremely high level. High-purity helium minimizes background interference, ensuring that the helium signal detected by the leak detector truly originates from a leak in the inspected workpiece, rather than impurities in the environment. For example, if the helium purity is low, it may contain other gaseous components, which may be misinterpreted as leak signals during leak detection or affect the leak detector's sensitivity to genuine helium signals. Therefore, using ultra-high purity helium is crucial to ensuring the accuracy and reliability of leak detection results.

[0055] In this embodiment, the detection accuracy of identifying weld leaks ≤0.01 mm refers to the smallest leak size that the helium mass spectrometer leak detector can identify. Identifying weld leaks with a diameter less than or equal to 0.01 mm means that the helium mass spectrometer leak detector can detect very small defects that might be overlooked under conventional detection methods. This high accuracy is crucial for battery sealing testing because even tiny leaks can lead to electrolyte leakage, battery performance degradation, and even safety hazards.

[0056] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A square battery sealing detection structure, the battery including a cover plate, a sealing sheet and a sealing plug connected from top to bottom to the cover plate, a cavity being formed between the sealing sheet and the sealing plug, characterized in that, The detection structure includes an air bag placed inside a cavity, the air bag containing the gas to be tested; the air bag is made of heat-resistant material, and the air bag includes an air bag opening and an air bag body, the air bag opening and the air bag body being connected by a narrow neck channel; The sealing sheet is made of paramagnetic metal. The air bag body covers the sealing plug. The narrow neck channel is on one side of the sealing plug. A first magnet is placed above the narrow neck channel. The first magnet is attracted to the cover plate on the bottom surface of the cavity to seal the narrow neck channel. After the sealing sheet is welded and cooled, a third magnet is placed on the sealing sheet. The third magnet drives the first magnet to separate from the cover plate, and the narrow neck channel opens to release gas.

2. The square battery sealing detection structure as described in claim 1, characterized in that, A second magnet is placed on the other side of the sealing plug. The second magnet is also attracted to the cover plate at the bottom of the cavity, and the top surface of the second magnet is in contact with the bottom surface of the air bag body. The third magnet synchronously drives the first magnet and the second magnet to separate from the cover plate. The second magnet squeezes the air bag body to accelerate the release of gas.

3. The square battery sealing detection structure as described in claim 2, characterized in that, The third magnet is a strong magnet, and the sealing sheet is an aluminum sealing sheet.

4. The square battery sealing detection structure as described in claim 1, characterized in that, The air bag opening is a circular hard plastic ring, and an inflation tube is inserted into the air bag opening.

5. The square battery sealing detection structure as described in claim 1, characterized in that, The heat-resistant material is silicone rubber, fluororubber, or perfluoroether rubber, which can withstand the heat radiation from welding the sealing sheet without melting or breaking.

6. The square battery sealing detection structure as described in claim 1, characterized in that, The cover plate at the bottom of the cavity has a first magnet slot and a second magnet slot.

7. The airtightness testing method for a square battery sealing testing structure as described in any one of claims 1-6, characterized in that, The specific steps include: First, insert the sealing plug into the injection hole of the cover plate; Then place the second magnet in the second magnet slot, and place the air bag on top of the sealing plug so that the air bag body covers the sealing plug; Then, a quantitative amount of the gas to be tested is injected into the gas bag, and then the first magnet is placed above the narrow neck channel, and the first magnet is inserted into the first magnet slot; Then, the sealing sheet is welded to the liquid injection port of the cover plate, and after the welding cools, a third magnet is placed on top of the sealing sheet; Next, it is checked whether the gas being tested escapes from the weld of the sealing sheet.

8. The airtightness testing method for a square battery sealing testing structure as described in claim 7, characterized in that, After placing the second magnet, insert the inflation tube into the round hard plastic ring opening. First, use negative pressure to fix the inflation tube opening and the round hard plastic ring opening, and then move the air bag to place it above the sealing plug.

9. The airtightness testing method for a square battery sealing testing structure as described in claim 7, characterized in that, After the third magnet is placed, the magnetic force of the third magnet drives the first magnet upward to disengage from the narrow neck channel, while simultaneously driving the second magnet upward to squeeze the air bag body, so that the gas being tested is fully released and fills the cavity.

10. The airtightness testing method for a square battery sealing testing structure as described in claim 7, characterized in that, The gas being tested is helium, and a helium mass spectrometer leak detector is used to detect the weld.

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