A fixture for testing the airtightness of lithium battery caps

Abstract

This utility model discloses a lithium battery cover airtightness testing fixture. The fixture includes a vent cover simultaneously covering the lithium battery cover and the weld patch, and a vent pipe fixedly connected to the vent cover. The vent cover includes an inner sealing wall, an outer sealing wall with one end joined to the inner sealing wall and surrounding its outer periphery, and a vent cavity formed between the two. The vent pipe connects to the vent cavity. The inner sealing wall presses firmly against the weld patch, and the outer sealing wall surrounds the weld patch and presses firmly against the lithium battery cover. This utility model discloses a lithium battery cover airtightness testing fixture that can detect the airtightness of the weld seam of the weld patch. Gas is discharged from the vent cavity through the vent pipe, forming an outlet channel that prevents leakage. During testing, simply covering the outer periphery of the weld patch with the vent cover is sufficient. The testing speed is fast, greatly improving the safety and efficiency of the test.

Description

[0001] This application claims priority to Chinese Patent Application No. 2024221299991, filed on August 31, 2024, entitled “A Fixture for Testing the Airtightness of a Lithium Battery Cover,” which is incorporated herein by reference in its entirety. Technical Field

[0002] This utility model relates to the field of battery gas detection auxiliary fixtures, and in particular to a lithium battery cover gas tightness detection fixture. Background Technology

[0003] The internal chemical system of lithium batteries is highly reactive and easily reacts with external moisture and air, leading to performance degradation or failure. Therefore, the airtightness of the packaging is crucial to the reliability and safety of lithium batteries. Thus, effectively testing the airtightness of lithium batteries to ensure that defective products do not enter the consumer market is of paramount importance.

[0004] Some square lithium batteries have their injection ports sealed with rubber stoppers after electrolyte filling; these ports are essentially through holes. Sealing the injection port ensures a certain degree of vacuum inside the battery. A weld patch is then laser-welded above the injection port for further sealing. The weld patch is attached to the battery casing at the injection port. An air bladder is built into the injection port, and a rubber stopper is placed at the bottom. When the battery cap is heated, the air bladder ruptures, filling the injection port with helium gas. If the weld patch on the battery cap has a weld leak, helium will leak out. For details on the technique of using welding heat to rupture the air bladder and then performing airtightness testing on the weld, please refer to the disclosure in Chinese Patent Application No. 202110102504.4.

[0005] Currently, the method for detecting gas leaks involves placing the entire battery in a vacuum chamber. If helium leaks, the detection device will capture helium molecules and send a signal. However, since the amount of helium released by the gasbag is very small, and the larger the measurement space, the more difficult it is to capture and measure the gas, how to stably and quickly detect the sealing performance of the solder patch has become an urgent problem to be solved. Utility Model Content

[0006] The main purpose of this utility model is to provide a lithium battery cover airtightness testing fixture, which aims to solve the problem that the existing airtightness testing method for repaired pieces is difficult to detect quickly due to the large measurement space.

[0007] To achieve the above objectives, this utility model provides a lithium battery cover airtightness testing fixture for testing the sealing performance of a weld patch welded to a lithium battery cover. The fixture includes a venting cover simultaneously covering both the lithium battery cover and the weld patch, and a venting pipe fixedly connected to the venting cover. The venting cover includes an inner sealing wall, an outer sealing wall with one end joined to the inner sealing wall and surrounding the outer periphery of the inner sealing wall, and a venting cavity formed between the two. The venting pipe communicates with the venting cavity. The inner sealing wall is pressed against the weld patch, and the outer sealing wall surrounds the periphery of the weld patch and presses against the lithium battery cover.

[0008] Preferably, the ends of the inner sealing wall and the outer sealing wall form a height difference, and the height of the inner sealing wall is less than the height of the outer sealing wall.

[0009] Preferably, the height difference is equal to the thickness of the weld patch.

[0010] Preferably, the cross-sections of the inner sealing wall and the outer sealing wall are arranged in parallel and spaced apart.

[0011] Preferably, the air guide cover is integrally formed.

[0012] Preferably, sealing rings are embedded at the ends of the inner sealing wall and the outer sealing wall.

[0013] Preferably, the sealing ring is a rubber sealing ring.

[0014] Preferably, the shapes of the inner sealing wall and the outer sealing wall are adapted to the outer contour of the weld patch.

[0015] Preferably, the air guide shroud is a metal air guide shroud.

[0016] Compared with the prior art, the lithium battery cover airtightness testing fixture provided by this utility model has the following beneficial effects:

[0017] The lithium battery cover airtightness testing fixture provided by this utility model presses the inner sealing wall tightly onto the weld patch, and the outer sealing wall surrounds the weld patch and presses it tightly onto the lithium battery cover, so that the gas guide cover surrounds the weld of the weld patch, allowing helium gas leaking from the weld to enter the gas guide cavity and then enter the gas sensor connected to it through the ventilation pipe. This allows the airtightness of the weld patch to be detected. Gas leaks from the weld, enters the gas guide cavity, and then enters the gas detection device at the rear end through the ventilation pipe. During testing, it is only necessary to cover the outer periphery of the weld patch. Because the space of the gas guide cavity is small, helium molecules will not disperse into a large space, making helium easier to capture, and the testing speed is fast, which greatly improves the efficiency and stability of the detection. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the test state of the lithium battery cover airtightness testing fixture provided by this utility model;

[0020] Figure 2 A perspective view of the lithium battery cover airtightness testing fixture provided by this utility model;

[0021] Figure 3 Another perspective view of the lithium battery cover airtightness testing fixture provided by this utility model;

[0022] Figure 4 This is a partial structural diagram of the inner or outer sealing wall.

[0023] The purpose, features, and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0027] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0028] Please refer to Figures 1-3 This utility model provides a lithium battery cover airtightness testing fixture. The lithium battery cover airtightness testing fixture 10 is used to test the sealing performance of a weld patch 30 welded to a lithium battery cover 20. The lithium battery cover 20 airtightness testing fixture includes a vent shroud 1 simultaneously covering the lithium battery cover 20 and the weld patch 30, and a vent pipe 3 fixedly connected to the vent shroud 1. The vent shroud 1 includes an inner sealing wall 11, an outer sealing wall 13 one end joined to the inner sealing wall 11 and surrounding the outer periphery of the inner sealing wall 11, and a vent cavity 15 formed between the two. The vent pipe 3 communicates with the vent cavity 15. The inner sealing wall 11 is pressed against the weld patch 30, and the outer sealing wall 13 surrounds the periphery of the weld patch 30 and presses against the lithium battery cover 20, so that the vent shroud 1 surrounds the weld seam of the weld patch 30. Thus, helium gas filling the injection port 40 will enter the weld through the leak point. The gas is introduced into the gas guiding cavity 15 and connected to a gas sensor via the ventilation pipe 3. This allows for the detection of the airtightness of the weld seam of the weld repair piece 30. In one preferred embodiment, the gas sensor is a helium detector. As those skilled in the art know, helium molecules have a small radius, thus allowing the detection of small weld seams. Therefore, a helium detector is an excellent airtightness testing instrument with extremely high accuracy. Of course, in other embodiments, if high accuracy is not required, other tracer gases, such as nitrogen, can be used, and the corresponding detector becomes a nitrogen detector. Gas leaks from the weld seam, enters the gas guiding cavity 15, and then enters the gas detection device at the rear end via the ventilation pipe 3. During testing, simply covering the outer periphery of the weld repair piece 30 with the gas guiding cover 1 is sufficient. Because the space of the gas guiding cavity 15 is small, helium molecules do not disperse into a large space, making them easier to capture and resulting in a fast testing speed. Therefore, using this testing fixture in conjunction with the corresponding gas detection device to test the weld airtightness of the weld repair piece 30 can greatly improve the efficiency and stability of the testing.

[0029] Preferably, in this embodiment, since the welding patch 30 is welded to the upper surface of the lithium battery cover 20, the height of the welding patch 30 protrudes above the highest upper surface of the lithium battery cover 20. Therefore, in order to make the fit between the inner sealing wall 11 and the welding patch 30 better, a height difference is formed between the ends of the inner sealing wall 11 and the outer sealing wall 13, and the height of the inner sealing wall 11 is less than the height of the outer sealing wall 13, that is, the length of the inner sealing wall 11 is shorter than the length of the outer sealing wall 13.

[0030] Furthermore, the height difference is equal to the thickness of the welding patch 30, so that the inner sealing wall 11 is pressed on the welding patch 30, and the bottom surface of the outer sealing wall 13 is just in contact with the upper surface of the lithium battery cover 20.

[0031] The inner sealing wall 11 and the outer sealing wall 13 are arranged with parallel and spaced sections, so that the space of the gas guide cavity 15 is formed between the inner sealing wall 11 and the outer sealing wall 13, forming a gas channel. The specific detection process is as follows: before the gas bag 60 melts and bursts, it is pressed onto the weld seam, and then the helium gas bag melts and bursts, releasing helium into the injection hole. The helium then enters the gas guide cavity 15 through the weld seam leak. Therefore, this detection fixture can capture helium molecules and confine them within the gas guide cavity 15, which then enters the gas detection device at the rear end through the ventilation pipe 3. Because the space of the gas guide cavity 15 is small, helium molecules are more easily detected. Once helium molecules are detected, a helium leak can be determined, indicating a poor seal on the weld repair piece.

[0032] Preferably, the air guide cover 1 is manufactured by integral molding, which is highly efficient.

[0033] Please see Figure 4 In addition, in order to improve the contact sealing between the inner sealing wall 11 and the outer sealing wall 13 and the welding piece 30 and the lithium battery cover 20, sealing rings 50 are embedded at the ends of the inner sealing wall 11 and the outer sealing wall 13 to further prevent gas from leaking from their contact points.

[0034] Specifically, the sealing ring 50 is made of rubber. The rubber sealing ring 50 has high elasticity and is formed during the application of external pressure to improve the sealing degree.

[0035] Furthermore, the shapes of the inner sealing wall 11 and the outer sealing wall 13 are adapted to the outer contour of the welding patch 30. In this way, the gas guide shroud 1 can better match the welding patch 30. When the welding patch 30 is circular, the gas guide shroud 1 is set to be circular; when the welding patch 30 is square, the gas guide shroud 1 is set to be square. Of course, when the welding patch 30 has other irregular shapes, the gas guide shroud 1 is also set to be irregular shapes.

[0036] Specifically, in this embodiment, the air guide is a metal air guide. Of course, in other embodiments, the air guide may also be made of other materials such as plastic.

[0037] The lithium battery cover 20 airtightness testing fixture provided by this utility model presses the inner sealing wall 11 onto the weld patch 30, and the outer sealing wall 13 surrounds the weld patch 30 and presses it onto the lithium battery cover 20, so that the gas guide shroud 1 surrounds the weld of the weld patch 30, allowing helium gas leaking from the weld to enter the gas guide cavity 15 and be connected to the gas sensor via the ventilation pipe 3. This allows the airtightness of the weld of the weld patch 30 to be detected. The gas is discharged from the gas guide cavity 15 through the ventilation pipe 3, forming an outlet channel that will not leak out. During testing, it is only necessary to cover the outer periphery of the weld patch 30 with the gas guide shroud 1. Since the space of the gas guide cavity 15 is small, the tracer helium gas is more easily captured, making the testing speed fast and greatly improving the efficiency and stability of the detection.

[0038] It should be noted that the tool used to weld the weld seam in this embodiment is a laser. Therefore, the clearance hole (not shown in the figure) formed between the inner sealing walls 11 of this inspection fixture provides space for the laser to irradiate the weld repair piece.

[0039] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A lithium battery cover airtightness testing fixture, used to test the sealing performance of a weld patch soldered onto a lithium battery cover, characterized in that, The device includes a venting cover that is simultaneously placed on the lithium battery cover and the welding patch, and a venting pipe that is fixedly connected to the venting cover. The venting cover includes an inner sealing wall, an outer sealing wall that is joined at one end to the inner sealing wall and surrounds the outer periphery of the inner sealing wall, and a venting cavity formed between the two. The venting pipe communicates with the venting cavity. The inner sealing wall is pressed against the welding patch, and the outer sealing wall surrounds the periphery of the welding patch and is pressed against the lithium battery cover.

2. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The inner sealing wall and the outer sealing wall have a height difference at their ends, and the height of the inner sealing wall is less than the height of the outer sealing wall.

3. The lithium battery cover airtightness testing fixture according to claim 2, characterized in that, The height difference is equal to the thickness of the weld patch.

4. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The cross-sections of the inner sealing wall and the outer sealing wall are arranged in parallel and spaced apart.

5. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The air guide cover is integrally molded.

6. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The ends of the inner sealing wall and the outer sealing wall are fitted with sealing rings.

7. The lithium battery cover airtightness testing fixture according to claim 6, characterized in that, The sealing ring is a rubber sealing ring.

8. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The shapes of the inner sealing wall and the outer sealing wall are adapted to the outer contour of the weld patch.

9. The lithium battery cover airtightness testing fixture according to claim 1, characterized in that, The air guide cover is a metal air guide cover.

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