Battery pack air tightness detection method, device and system and battery pack

Abstract

The invention provides an air tightness detection method, device and system of a battery pack (100) and the battery pack (100). The detection method comprises the following steps: placing a gas source device in the battery pack (100); sealing the battery pack case (10); and in response to the conformity of the preset condition, detecting the gas concentration of the gas source in the battery pack (100), and determining whether the battery pack (100) meets the airtightness standard or not. The gas tightness detection system comprises a processor, a gas source device, a gas sensor, a first heating assembly used for heating a battery monomer (20) and a second heating assembly used for heating gas of the gas source. The battery management system can obtain a more accurate gas tightness result by detecting the gas concentration of the gas source.

Description

A battery pack airtightness detection method, device, system and battery pack Technical Field

[0001] The present disclosure relates to the technical field of battery testing, and in particular to a method, device, system and battery pack for detecting the air tightness of a battery pack. Background Art

[0002] With the rapid development of new energy vehicles in recent years, electric vehicle safety has received increasing attention. The battery pack is the source of power for new energy vehicles, and its sealing is crucial to their performance and safety. "GB / T 4208-2017 Degrees of Protection Provided by Enclosures (IP Code)," administered by the National Electrical Safety Standardization Technical Committee, sets specific requirements for testing the IP rating of battery pack enclosures for new energy vehicles. Therefore, employing a fast, efficient, and safe method to test battery pack sealing has become an even more crucial step. Technical issues

[0003] The present disclosure aims to solve at least one of the technical problems existing in the background technology. To this end, one object of the present disclosure is to provide a battery pack airtightness detection method, device, system and battery pack. Technical Solutions

[0004] An embodiment of the first aspect of the present disclosure provides a method for detecting the air tightness of a battery pack, the method comprising the following steps: placing a gas source device in the battery pack; sealing the aforementioned battery pack; in response to meeting a preset condition, detecting the concentration of the gas source gas in the battery pack to determine whether the aforementioned battery pack meets the air tightness standard; wherein the aforementioned gas source device is used to release the aforementioned gas source gas; the aforementioned preset condition includes placing the battery pack for a first preset time period.

[0005] In one or more embodiments of the present disclosure, the step of detecting the concentration of the gas source gas in the battery pack in response to meeting the preset conditions and determining whether the battery pack meets the air-tightness standard includes the following sub-steps: in response to meeting the preset conditions, recording the time when the gas source gas in the battery pack reaches the maximum concentration; after a second preset time period has passed from the time of the maximum concentration, detecting the first gas source gas concentration in the battery pack, and determining whether the battery pack meets the air-tightness standard based on the first gas source gas concentration.

[0006] In one or more embodiments of the present disclosure, the step of detecting the concentration of the gas source gas in the battery pack in response to meeting the preset conditions and determining whether the battery pack meets the air-tightness standard includes the following sub-steps: determining the concentration change rate of the gas source gas in the battery pack in response to meeting the preset conditions; and determining whether the battery pack meets the air-tightness standard based on the concentration change rate of the gas source gas.

[0007] In one or more embodiments of the present disclosure, the step of determining the rate of change of the concentration of the aforementioned gas source gas in the aforementioned battery pack in response to meeting the preset conditions includes the following sub-steps: detecting the second gas source gas concentration in the aforementioned battery pack in response to meeting the preset conditions; detecting the third gas source gas concentration in the aforementioned battery pack after a second preset time period; and determining the rate of change of the aforementioned gas source gas in the aforementioned battery pack based on the second gas source gas concentration and the third gas source gas concentration.

[0008] In one or more embodiments of the present disclosure, the step of determining the rate of change of the concentration of the aforementioned gas source gas in the aforementioned battery pack in response to meeting the preset conditions includes the following sub-steps: in response to meeting the preset conditions, recording the maximum concentration reached by the gas source gas in the aforementioned battery pack; detecting the fourth gas source gas concentration in the aforementioned battery pack after a second preset time has passed since the aforementioned maximum concentration was reached; and determining the rate of change of the concentration of the aforementioned gas source gas in the battery pack based on the aforementioned maximum concentration and the aforementioned fourth gas source gas concentration.

[0009] In one or more embodiments of the present disclosure, the gas source device includes dry ice.

[0010] In one or more embodiments of the present disclosure, the aforementioned preset conditions further include: heating the aforementioned gas source device.

[0011] In one or more embodiments of the present disclosure, the second preset duration is greater than 2 hours.

[0012] An embodiment of the second aspect of the present disclosure provides an airtightness detection device for a battery pack, comprising: a first module, which places an air source device in the battery pack; a second module, which seals the aforementioned battery pack; a third module, which detects the concentration of the air source gas in the battery pack in response to meeting a preset condition, and determines whether the aforementioned battery pack meets the airtightness standard; wherein the aforementioned air source device is used to release the aforementioned air source gas; the aforementioned preset condition includes placing the aforementioned battery pack for a first preset time period.

[0013] An embodiment of the third aspect of the present disclosure provides a sealing head for airtightness testing of a battery pack, comprising: an outer shell; a sealing body, which is arranged in the outer shell and covers an explosion-proof valve of the battery pack, wherein the sealing body is provided with a connecting hole; a detecting member, at least a portion of which is arranged in the outer shell, wherein the detecting member includes a main body and a probe part, the probe part is provided with a gas sensor for detecting source gas, the probe part is configured to protrude from the main body and pass through the connecting hole; the detecting member also includes a processor and a memory, the memory stores a computer program, and when the computer program is executed by the processor, the processor implements the steps of the method of the embodiment of the first aspect of the present disclosure.

[0014] According to an embodiment of the fourth aspect of the present disclosure, a battery pack airtightness detection system is provided, comprising: a gas source device for releasing gas source gas; a first heating component for heating the battery pack; a second heating component for heating the gas source device; and a gas concentration sensor for detecting the concentration of the gas source gas; wherein a processor is electrically coupled to the first heating component, the second heating component, and the gas concentration sensor. The battery management system further comprises a memory storing a computer program. When the computer program is executed by the processor, the steps of the method according to the first aspect of the present disclosure are performed.

[0015] An embodiment of the fifth aspect of the present disclosure provides a battery pack, which includes the airtightness detection device of the embodiment of the second aspect of the present disclosure or the airtightness detection system of the embodiment of the third aspect.

[0016] The above description is only an overview of the technical solution of the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present disclosure more obvious and easy to understand, the specific implementation methods of the present disclosure are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments according to the present disclosure and should not be regarded as limiting the scope of the present disclosure.

[0018] FIG1 is a schematic structural diagram of a vehicle according to some embodiments of the present disclosure;

[0019] FIG2 is a schematic diagram of the exploded structure of a battery according to some embodiments of the present disclosure;

[0020] FIG3 is a flow chart of an airtightness detection method according to some embodiments of the present disclosure;

[0021] FIG4 is a circuit block diagram of an airtightness detection system provided in some embodiments of the present disclosure;

[0022] FIG5 is a graph showing the change in source gas concentration over time according to some embodiments of the present disclosure;

[0023] FIG6 is a graph showing the change in source gas concentration over time according to some embodiments of the present disclosure;

[0024] FIG7 is a graph showing the change in source gas concentration over time according to some embodiments of the present disclosure;

[0025] FIG8 is a circuit block diagram of an airtightness detection system provided in some embodiments of the present disclosure;

[0026] FIG9 is a hardware schematic diagram of an airtightness detection head provided in some embodiments of the present disclosure;

[0027] FIG10 is a circuit block diagram of an airtightness detection head provided in some embodiments of the present disclosure;

[0028] Description of reference numerals:

[0029] 1000 vehicles; 100 battery packs; 200 controllers; 300 motors;

[0030] 10 housing; 11 first part; 11a explosion-proof valve hole; 12 second part; 20 battery cell;

[0031] 80: sealing head; 81: outer shell; 82: sealing body; 82a: communicating hole; 83: detection component; 83a: detection body; 83b: probe part. Modes for Carrying Out the Invention

[0032] The following embodiments of the technical solution of the present disclosure are described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present disclosure and are therefore only examples and are not intended to limit the scope of protection of the present disclosure.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the terms "including" and "having" and any variations thereof in the specification and claims of the present disclosure and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of the present disclosure, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0037] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0038] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0039] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0040] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0041] In industrial production environments, the air tightness test of battery packs is time-consuming and labor-intensive due to the water spraying method, which has low production efficiency and is difficult to adapt to the requirements of large-scale production lines. Therefore, the current production line mainly uses positive pressure testing or negative pressure testing to test the waterproof and airtightness of battery packs. For example, an air tightness test tool that is compatible with the explosion-proof valve or balancing valve is made and installed on the explosion-proof valve or balancing valve. The explosion-proof valve or balancing valve is used to press gas into the battery pack or suck gas out of the battery pack, so that the entire battery pack presents a positive or negative pressure for a short period of time. By detecting the degree of pressure difference attenuation in the battery pack over a period of time, it is determined whether the air tightness performance of the battery pack meets the requirements. However, because the gas passes through the breathable membrane of the explosion-proof valve or balancing valve during the test, it is blocked by the breathable membrane, and the air permeability is significantly reduced, resulting in excessively long test times and affecting the production cycle.

[0042] Based on the above considerations, the applicant has provided a method, device and system for detecting the air tightness of a battery pack, in which an air source device is disposed inside the battery pack box.

[0043] The battery cells disclosed in the embodiments of the present disclosure can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in the present disclosure can be used to form the electrical device.

[0044] The present disclosure provides a method and apparatus for thermal management control of a vehicle battery, including but not limited to passenger cars, commercial vehicles, engineering vehicles, and automated guided vehicles (AGVs). The vehicle battery can be a non-replaceable battery that supports charging the entire vehicle, or a replaceable battery that supports recharging after being separated from the vehicle.

[0045] For the convenience of description, the following embodiments are described by taking the vehicle 1000 according to an embodiment of the present disclosure as an example.

[0046] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle provided by some embodiments of the present disclosure. Vehicle 1000 can be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle (hereinafter referred to as an electric vehicle). A battery pack 100 is disposed within vehicle 1000. Battery pack 100 can be located at the bottom, front, or rear of vehicle 1000. Battery pack 100 can be used to power vehicle 1000. For example, battery pack 100 can serve as the operating power source of vehicle 1000.

[0047] In some embodiments of the present disclosure, the battery pack 100 can serve not only as the operating power source of the vehicle 1000, but also as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0048] Please refer to Figure 2, which is an exploded view of a battery provided in some embodiments of the present disclosure. A battery pack 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10. The housing 10 provides a storage space for the battery cells 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cells 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, overlapping the open side of the second portion 12, so that the first and second portions 11 and 12 together define a storage space. Alternatively, the first and second portions 11 and 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first and second portions 11 and 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, or a blade shape. The box body 11 is provided with an explosion-proof valve 11 a , and the explosion-proof valve 11 a has a waterproof and breathable membrane therein that allows gas to pass through.

[0049] In the battery pack 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that the multiple battery cells 20 are connected both in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed in the housing 10. Of course, the battery pack 100 may also be a battery module formed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection, and then the multiple battery modules are further connected in series, in parallel, or in a hybrid connection to form an entire battery cell, and then housed in the housing 10. The battery pack 100 may also include other structures. For example, the battery pack 100 may also include a busbar component for electrically connecting the multiple battery cells 20. Each battery cell 20 may be a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0050] According to the airtightness testing scheme known to the present inventors, the tester first connects the vacuum pump's exhaust pipe to the explosion-proof valve 11a of the box 11 and pumps the interior of the box 11 to a negative pressure through the explosion-proof valve 11a. When the pressure inside the box 11 reaches -10,000 Pa, the tester stops pumping air into the box 11. After 10 minutes, the pressure inside the box 11 is tested again. The pressure changes before and after the test are compared to determine whether the battery pack 100 meets the airtightness requirements.

[0051] However, on the one hand, the air permeability of the waterproof breathable membrane is generally small, the air extraction speed is slow, and the detection efficiency is low. If the power of the vacuum pump is increased and a higher negative pressure is used to accelerate the air extraction, the waterproof breathable membrane may be broken, resulting in damage to the explosion-proof valve 11a. The detection speed is difficult to meet the requirements of industrial production. On the other hand, since the material of the box body 11 itself is relatively thin, the pressure it can withstand is relatively small, and it can usually only withstand an airtightness test pressure of more than ten kPa. During the test, the vacuum pump cannot be separated from the battery pack. In order not to affect the production rhythm, the airtightness test cycle is usually set to 3-15 minutes. During the test period, the air pressure in the battery pack changes little and is easily affected by environmental factors such as temperature and humidity, and cannot meet the requirements of high-precision airtightness detection. In addition, the vacuum pump's exhaust pipe needs to be repeatedly plugged and unplugged from the explosion-proof valve interface during long-term testing, and the pipe mouth is easily worn and deformed, resulting in large errors in the test results.

[0052] Some embodiments of the present disclosure provide a method for detecting the airtightness of a battery pack. The battery pack of this embodiment can be referred to FIG. 2 .

[0053] Referring to Figure 3 , this testing method includes the following steps: placing an air source device within the housing 10 of the battery pack 100; sealing the housing 10; and, when a preset condition is met, detecting the concentration of the source gas within the housing 10 to determine whether the battery pack 100 meets the airtightness standard. The air source device is used to release the source gas, and the preset condition includes leaving the battery pack 100 for a preset period of time.

[0054] Optionally, the gas source device is dry ice, or a container containing dry ice. Dry ice sublimates into carbon dioxide gas at room temperature and pressure. By detecting changes in the carbon dioxide concentration within the battery pack 100, it can be determined whether the battery pack 100 meets the airtightness standard. Figure 5 is a graph showing the change in the concentration of the gas source over time, provided in some embodiments of the present disclosure. Referring to Figure 5, since the space within the battery pack 100 is known, a preset weight of dry ice is placed. After a relatively long storage period t1 (for example, 10 hours), the carbon dioxide concentration C1 within the box is detected by a carbon dioxide concentration sensor built into the box body 10. If the carbon dioxide concentration C1 is higher than or equal to the preset concentration value, the battery pack 100 meets the airtightness standard; if the carbon dioxide concentration C1 is lower than the preset concentration value, the battery pack 100 does not meet the airtightness standard. This preset concentration value can be obtained by testers through multiple experiments.

[0055] It should be noted that the “placement for a preset period of time” mentioned in the present disclosure should be understood as maintaining the airtightness of the box 10 for a period of time. During this placement period, the battery pack can be subjected to high temperature and high pressure testing, electrical function testing, transportation and storage, etc. In some embodiments, the natural sublimation of dry ice can be waited for by taking advantage of the fact that the sublimation point of dry ice is higher than room temperature. In other embodiments, in order to speed up the sublimation rate of dry ice, the dry ice can also be heated by a heating element. In other embodiments, the order of the tests can also be adjusted, and the dry ice can also be heated by a heating element such as a thermistor. The specific details will be described in detail in subsequent embodiments.

[0056] Testing gas concentration provides more accurate results than differential pressure methods. Gas concentration changes significantly after prolonged storage, leading to higher test accuracy. Furthermore, even after sealing, the battery pack can still be used for subsequent functional testing, storage, and transportation, improving production cycle time.

[0057] Some embodiments of the present disclosure also provide a method for testing the air tightness of a battery pack. The battery pack of this embodiment can be seen in Figure 2 . The battery pack 100 has a housing 10 containing battery cells 20 and an air tightness testing system consisting of a battery management system (BMS), an air source, and other peripheral circuits (not shown). In this embodiment, the air source is dry ice.

[0058] Refer to Figure 2. The battery pack 100 includes a case 10 and a battery cell 20, and the battery cell 20 is accommodated in the case 10. The case 10 is used to provide a storage space for the battery cell 20. The case 10 includes a first part 11 and a second part 12. The first part 11 and the second part 12 cover each other, and the explosion-proof valve 11a is sealed with a head or the like to achieve sealing of the case 10. A space for accommodating the air source device is formed in the case 10. Exemplarily, the cavity formed between the battery cell 20 and the inner wall of the case 10 has a shape corresponding to the air source device, which prevents the air source device from moving in the case, forming local condensation, and damaging the internal structure of the battery pack. In some embodiments, the first part 11 and / or the second part 12 are provided with a buckle for fixing the air source device. In other embodiments, the first part 11 and / or the second part 12 are provided with a groove for accommodating the air source device.

[0059] Referring to Figure 4 , the airtightness detection system is located within the battery pack 100 and consists of peripheral circuits such as the battery management system (BMS), a temperature and humidity sensor (temperature sensor), a carbon dioxide concentration sensor, a driver module for driving a high-voltage relay, a heater for heating the battery cells, and a heating unit for heating the air supply device. The heater can be a positive temperature coefficient heating resistor element or a silicone heating film, or a charging and discharging circuit that utilizes DC-DC charging and discharging between multiple strings of battery cells for heating. The heating unit is a small heating device independent of the heater and is used to heat the air supply device. In some embodiments, the airtightness detection system is electrically coupled to a host computer located outside the battery pack 100 through the BMS. The BMS receives airtightness detection commands from the host computer and transmits the rate of change of the carbon dioxide concentration to the host computer. In some embodiments, the host computer can be a computer, programmable logic controller (PLC), or similar device, and determines whether the airtightness meets the requirements through communication with the BMS.

[0060] a) Assembly Phase: Place the air source device inside the battery pack. Specifically, before installing the battery pack cover, testers use a robotic arm to remove the air source device from the cold storage compartment and place it inside the cavity of the battery pack 100. The low-voltage wiring harness of the heating unit is then connected to the main control box of the BMS. Finally, the cover is installed and the battery pack is sealed. For example, in this solution, a dry ice block is used as the air source device. This dry ice block is attached with a heating unit (e.g., a PTC ceramic heating element) for heating the dry ice. This heating unit is connected to the BMS via a low-voltage wiring harness and starts and stops heating the dry ice based on control signals from the BMS. In some embodiments, the dry ice is placed in the center of the battery pack 100 to ensure a uniform distribution of carbon dioxide concentration within the battery pack 100. In some embodiments, the dry ice can also be placed directly on the heater used to heat the battery cells 20 or on the battery cells 20. After the battery pack 100 is sealed, the heating unit is used to heat the dry ice inside the battery pack 100. By heating the dry ice, not only the speed of dry ice sublimation is increased, but also the dry ice is prevented from absorbing a large amount of heat during sublimation, which would damage the internal structure of the battery pack. In some other embodiments, the dry ice can be heated using a heater used to heat the battery cells. The BMS detects the temperature of each battery cell 20 through a temperature sensor and controls the heater to avoid the local temperature of the battery cell 20 close to the dry ice being too low, accelerating the aging of some battery cells 20 and affecting the consistency of the performance of the battery cell 20. During the heating period, other test items such as shockproof tests can be performed on the battery pack. In addition, the wear of the head of the vacuum tooling due to repeated plugging and unplugging and the problem of the explosion-proof valve not closing are avoided. In some embodiments, in order to prevent the dry ice from moving, the robotic arm fixes the dry ice to a fixed groove or fixed bracket in the battery pack 100 when placing the dry ice.

[0061] b) Electrical testing phase: The tester connects to the battery pack's BMS via an external device (host computer). The BMS activates the heating element of the gas source device, prompting the dry ice to sublime rapidly. Referring to Figure 6, the carbon dioxide concentration within the battery pack 100 first increases significantly at t0 until reaching a peak concentration C0. The change in carbon dioxide concentration over this period is recorded. In Figure 6, the vertical axis represents concentration in ppm (parts per million), which is the volume of the source gas (carbon dioxide) per one million volumes of air. The horizontal axis represents time in minutes.

[0062] c) Voltage stabilization stage: After the electrical measurement stage is completed, the package is transferred to the storage area to allow the concentration inside the package to stabilize and decrease.

[0063] d) Testing phase: After the battery pack 100 has been placed for a first preset time, the carbon dioxide sensor connected to the BMS is used to detect the gas source concentration inside the battery pack, and the first time t1 and the first concentration C1 at this time are recorded; the battery pack is then placed for a second preset time (the placement time is △t), and finally the pack is tested for concentration, and the second time t2 and the second concentration C2 are recorded. The concentration difference between the first concentration and the second concentration is △C=C1-C2. In some embodiments, the placement time of △t is greater than 2 hours, thereby avoiding the problem of inaccurate airtightness test results caused by excessive test time. In some other embodiments, the placement time of △t is between 30 minutes and 1 hour, thereby speeding up the detection speed.

[0064] e) Determination stage: Calculate the leakage rate of the battery pack 100 based on ΔC / Δt = (C1-C2) / (t2-t1). If the leakage rate is lower than the preset standard, the battery pack is judged to meet the airtightness requirements and has passed the airtightness test. Otherwise, it has failed the airtightness test.

[0065] In yet other embodiments, the leakage rate of the battery pack 100 can be calculated based on the difference between the measured peak carbon dioxide concentration and the measured carbon dioxide concentration after a storage time Δt. Referring to Figure 7, after heating the dry ice, the BMS uses the carbon dioxide concentration sensor to record a time-varying curve of the carbon dioxide concentration within the battery pack 100, obtaining the peak carbon dioxide concentration C1 and the concentration C2 after a storage time Δt (a second predetermined time). The leakage rate of the battery pack 100 can be calculated using the formula ΔC / Δt = (C1-C2) / (t2-t1).

[0066] This allows for more precise detection of battery pack airtightness, meeting the requirements for higher-precision sealant testing and grading. It also overcomes the shortcomings of positive and negative pressure methods, which can lead to inaccurate test results due to factors such as improper plug installation and repeated insertion and removal of plug seals. It also reduces overall airtightness testing time.

[0067] Some embodiments of the present disclosure also provide a head for detecting the air tightness of a battery pack. Referring to Figures 9 and 10, Figure 9 is a hardware schematic diagram of the air tightness detection head, and Figure 10 is a circuit block diagram of the air tightness detection head. The head for air tightness detection is used to be installed on the explosion-proof valve or balancing valve of the battery pack, providing air tightness for the battery pack while judging based on the concentration of the gas source in the battery pack. The head includes: an outer shell 81 for connecting to the battery pack case, a sealing body 82 and a detection part 83 arranged in the outer shell. Among them, the sealing body 82 is used to be inserted into the explosion-proof valve hole (for example, 11a in Figure 2) to provide sealing for the explosion-proof valve hole. The sealing body 82 is usually made of a material with a certain degree of ductility such as rubber. A connecting hole 82a is provided on the sealing body 82; at least a portion of the detection member 83 is disposed within the outer shell. The detection member includes a probe portion 83a and a main body 83b. The probe portion 83a is provided with a gas sensor for detecting the source gas. The probe portion 83a is configured to protrude from the main body 83b and pass through the connecting hole 82a, thereby detecting the carbon dioxide concentration within the explosion-proof valve hole 11a while ensuring the airtightness of the sealing body 83. The detection member 83 also includes a processor and a memory. The memory stores a computer program that, when executed by the processor, causes the processor to implement the steps of the method of the embodiment of the present disclosure. In some embodiments, the detection member 83 also includes a display module, such as an LED digital tube, for displaying the carbon dioxide concentration or the result of the airtightness test. The outer shell 81 is provided with a through hole in the display module so that the tester can view the above-mentioned result information. In other embodiments, the detection member 83 also includes a wireless communication module. The airtightness test head transmits the carbon dioxide concentration information to the host computer via the wireless communication module. The host computer processor determines whether the battery pack corresponding to the head meets the airtightness requirements. For example, the wireless communication module can be an RFID (Radio Frequency Identification) transmitter module. This allows batch testing of battery packs for airtightness during storage. This plug can meet higher testing accuracy requirements.

[0068] Some embodiments of the present disclosure also provide an airtightness detection device for a battery pack, comprising: a first module, which places an air source device in the battery pack; a second module, which seals the aforementioned battery pack; a third module, which detects the concentration of the air source gas in the battery pack in response to meeting a preset condition, and determines whether the aforementioned battery pack meets the airtightness standard; wherein the aforementioned air source device is used to release the aforementioned air source gas; the aforementioned preset condition includes placing the aforementioned battery pack for a first preset time period.

[0069] Some embodiments of the present disclosure also provide a battery pack airtightness detection system. Referring to FIG8 , the airtightness detection system includes: a gas source device for releasing carbon dioxide; a heating unit for heating the battery pack, a heating unit for heating carbon dioxide, a gas concentration sensor for detecting the concentration of the aforementioned gas source, and a BMS. The BMS includes a processor and a memory. The processor is electrically coupled to the aforementioned first heating component, the aforementioned second heating component, and the aforementioned gas concentration sensor. The aforementioned memory stores a computer program. When the aforementioned computer program is executed by the aforementioned processor, the steps of the method of other embodiments of the present disclosure are performed.

[0070] Some embodiments of the present disclosure further provide a battery pack, which includes the airtightness detection device of an embodiment of the present disclosure or the airtightness detection system of an embodiment.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present disclosure, and they should all be included in the scope of the claims and specification of the present disclosure. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present disclosure is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for detecting the air tightness of a battery pack, characterized in that: The following steps are involved: Place the gas source device inside the battery pack; sealing the battery pack; In response to a preset condition being met, detecting a concentration of a gas source in the battery pack to determine whether the battery pack meets an airtightness standard; Wherein, the gas source device is used to release the gas source gas; the preset condition includes placing the battery pack for a first preset time.

2. The method according to claim 1, characterized in that In response to a preset condition being met, the step of detecting the concentration of the gas source in the battery pack to determine whether the battery pack meets the airtightness standard includes the following sub-steps: In response to meeting a preset condition, recording the time when the gas source gas in the battery pack reaches a maximum concentration; After a second preset time has passed since the time of the maximum concentration, the concentration of the first gas source in the battery pack is detected, Determine whether the battery pack meets an airtightness standard based on the first gas source gas concentration.

3. The method according to claim 1, characterized in that The step of detecting the concentration of the gas source in the battery pack in response to meeting the preset condition to determine whether the battery pack meets the airtightness standard includes the following sub-steps: In response to a preset condition being met, determining a concentration change rate of the source gas within the battery pack; Whether the battery pack meets the airtightness standard is determined according to the concentration change rate of the source gas.

4. The method according to claim 3, characterized in that The step of determining the rate of change of the concentration of the source gas in the battery pack in response to meeting a preset condition includes the following sub-steps: In response to meeting a preset condition, detecting a concentration of a second gas source gas in the battery pack; After a second preset time period, detecting a gas concentration of a third gas source in the battery pack; The change rate of the source gas in the battery pack is determined according to the second source gas concentration and the third source gas concentration.

5. The method according to claim 3, characterized in that The step of determining the rate of change of the concentration of the source gas in the battery pack in response to meeting a preset condition includes the following sub-steps: In response to meeting a preset condition, recording a maximum concentration of the gas source gas within the battery pack; After a second preset time has passed since the maximum concentration is reached, detecting a concentration of a fourth gas source in the battery pack; The concentration change rate of the source gas in the battery pack is determined according to the maximum concentration and the fourth source gas concentration.

6. The method according to claims 1 to 5, characterized in that The gas source device includes dry ice.

7. The method according to claims 1 to 5, characterized in that The preset condition also includes: heating the gas source device.

8. The method according to claims 1 to 5, characterized in that The second preset duration is greater than 2 hours.

9. A battery pack airtightness detection device, characterized in that include: A first module, which places an air source device in the battery pack; a second module that seals the battery pack; a third module, in response to meeting a preset condition, detecting a concentration of a gas source in the battery pack to determine whether the battery pack meets an airtightness standard; The gas source device is used to release the gas source gas; the preset condition includes placing the battery pack for a first preset time.

10. A sealing head for testing the air tightness of a battery pack, characterized in that: include: outer shell; a sealing body, which is disposed in the outer shell and covers the explosion-proof valve of the battery pack, wherein the sealing body is provided with a communication hole; a detection member, at least a portion of which is disposed within the outer shell, wherein the detection member comprises a main body and a probe portion, the probe portion being provided with a gas sensor for detecting source gas, the probe portion being configured to protrude from the main body and pass through the communication hole; The detection component includes a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor implements the steps of the method according to any one of claims 1 to 8.

11. A battery pack air tightness detection system, characterized in that include: A gas source device for releasing the gas source gas; a first heating assembly, configured to heat the battery pack; a second heating component, which is used to heat the gas source device; A gas concentration sensor, used to detect the concentration of the source gas; Wherein, the processor is electrically coupled to the first heating component, the second heating component and the gas concentration sensor.

12. The airtightness detection system according to claim 11, characterized in that: The battery management system further comprises a memory storing a computer program, wherein when the computer program is executed by the processor, the processor is enabled to implement the steps of the method according to any one of claims 1 to 8.

13. A battery pack, characterized in that It includes the airtightness detection device according to claim 9 or the airtightness detection system according to claim 11.

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