Air tightness test system and test method for fuel cell membrane electrode

Abstract

The invention relates to the technical field of fuel cell membrane electrode testing, and discloses a fuel cell membrane electrode airtightness testing system and method, and the system comprises a tool clamp which comprises a cavity and a clamping assembly, the cavity is in a shell shape, and the top of the cavity is open; the clamping assembly is used for clamping a sample membrane electrode and sealing and fixing the sample membrane electrode at the top opening of the chamber; the gas supply mechanism is used for supplying helium to the inner cavity of the chamber, enabling the inner side pressure of the sample membrane electrode to be higher than the outer side pressure and forming a stable pressure difference; and the detection mechanism comprises a helium leak detector and a mechanical arm, and the mechanical arm grabs the helium leak detector to carry out global detection and smelling on the outward surface of the sample membrane electrode to find leakage points and records the leakage rate of each leakage point. According to the air tightness test system and the test method, whether the membrane electrode leaks or not can be conveniently and efficiently judged, the position of a leakage point is positioned, and the area of the leakage point is estimated.

Description

Technical Field

[0001] This invention relates to the field of fuel cell membrane electrode testing technology, and specifically to a fuel cell membrane electrode airtightness testing system and method. Background Technology

[0002] Currently, in the early stages of fuel cell R&D, it is essential to test and evaluate the membrane electrode assembly (MEA) of a fuel cell in the form of a single cell. As the most fundamental performance characteristic of the MEA, airtightness has a decisive impact on almost all aspects of fuel cell development, including pre-assembly, operation, and post-test re-evaluation. Therefore, how to test the airtightness of the MEA and extract more detailed and effective information from this test method is one of the key technologies in the field of fuel cell development and testing.

[0003] Among the relevant technologies, there are currently three main methods for testing the airtightness of membrane electrodes, as follows: The first method, disclosed in the China Association of Automobile Manufacturers group standard T / CAAMTB 12-2020 "Test Method for Membrane Electrode of Proton Exchange Membrane Fuel Cell", is a test method for membrane electrode leakage rate. Based on the principle of pressure drop leak detection, it measures the flow rate of gas leaking from the anode to the cathode of the membrane electrode per unit area per unit time under a certain pressure difference.

[0004] The second method originates from the wet immersion method in GB / T 20042.5-2009 "Proton Exchange Membrane Fuel Cells Part 5: Membrane Electrode Test Methods". Specifically, the fuel cell membrane electrode is installed in a fixture, and a test gas (such as hydrogen, air, or nitrogen) at a certain pressure is introduced into the fixture's inlet. After the gas flow rate stabilizes, the membrane electrode and fixture are completely submerged in water. Visual inspection is used to check for bubbles emerging from the water to determine if there is any leakage in the membrane electrode, and the location of the leak is determined based on the location of the bubbles.

[0005] The third method involves using an infrared thermal imager to scan the surface of the membrane electrode and determine the leak point by identifying the location of hot spots. Specifically, 100°C water vapor is introduced at a certain pressure into the cavity between the tooling fixture and the membrane electrode. If a leak point exists, the leaking water vapor will pass through the leak point to the outside of the membrane electrode. When the infrared thermal imager scans the high-temperature water vapor, it will identify the leak point of the membrane electrode in a distinct deep red color, thus determining whether there is a leak and its location.

[0006] However, the first method, because all test samples are within a fixture, can only evaluate the airtightness of the membrane electrode by measuring its leakage flow rate, and cannot determine the location and size of leak holes. The second method is limited in that it cannot relatively describe the size of each leak point. The third method also cannot relatively describe the size of each leak point, and is relatively cumbersome to operate (water vapor must be freshly prepared). Summary of the Invention

[0007] This application provides a system and method for testing the airtightness of a fuel cell membrane electrode, which can conveniently and efficiently determine whether the membrane electrode is leaking, locate the leak point, and estimate the size of the leak area.

[0008] In a first aspect, this application provides a gas tightness testing system for a fuel cell membrane electrode assembly, comprising: A tooling fixture comprising a chamber and a clamping assembly, wherein the chamber is shell-shaped with an open top, and the clamping assembly clamps and seals the sample membrane electrode to the top opening of the chamber; The gas supply mechanism is used to supply helium gas to the internal cavity of the chamber, so that the pressure inside the sample membrane electrode is higher than the pressure outside and a stable pressure difference is formed. The testing facility includes a helium leak detector and a robotic arm. The robotic arm grasps the helium leak detector and performs a full-area sniffing to find leaks on the side of the sample membrane electrode facing outwards, and records the leakage rate of each leak.

[0009] In conjunction with the first aspect, in one embodiment, the helium leak detector is calibrated beforehand using several standard leak holes to determine the leakage rate. During actual testing, the measured leakage rate corresponds to the estimated area of ​​the leak point.

[0010] In conjunction with the first aspect, in one embodiment, the robotic arm drives the helium leak detector to move in a serpentine pattern on the side of the sample membrane electrode facing outwards, probing row by row or column by column at equal intervals according to a set distance. During the detection process, when the real-time leakage rate of the helium leak detector is greater than zero, the surrounding area is gradually probed until the leakage rate reaches its maximum value, thus locating the leak point.

[0011] In conjunction with the first aspect, in one embodiment, the airtightness testing system further includes a vernier caliper, which is used to measure the XY coordinates of the leak point on the side of the sample membrane electrode facing outward after locating the leak point.

[0012] In conjunction with the first aspect, in one embodiment, the airtightness testing system further includes a controller for receiving the leakage rate from a helium leak detector, and for controlling the robotic arm to move row by row or column by column at designed intervals, and for reducing the step distance between adjacent rows or columns when the real-time leakage rate is greater than zero.

[0013] In conjunction with the first aspect, in one embodiment, the clamping assembly includes a plate frame and a filter screen, with the filter screen, sample membrane electrode, and plate frame arranged sequentially from the top surface of the chamber upwards; the plate frame uses a plurality of screws to press and seal the filter screen and sample membrane electrode to the top opening of the chamber.

[0014] In conjunction with the first aspect, in one embodiment, the anode side of the sample membrane electrode faces outward and the cathode side faces inward; a stable pressure difference of more than 5 kPa is formed between the cathode side and the anode side.

[0015] In conjunction with the first aspect, in one embodiment, the chamber includes an inlet and an outlet; the gas supply mechanism includes a helium storage cylinder, a pressure reducing valve, a pressure gauge, and a manual switch valve. The outlet of the helium storage cylinder is connected in sequence to the pressure reducing valve, the pressure gauge, and the inlet via a pipe. The outlet is connected to the manual switch valve via a pipe. The manual switch valve is normally closed and is opened and closed after the test is completed.

[0016] Secondly, embodiments of this application provide a testing method based on the above-described airtightness testing system, comprising the following steps: The sample membrane electrode is held in place by a clamping assembly, and the clamping assembly with the sample membrane electrode is sealed and fixed to the top opening of the chamber. Helium gas is introduced into the cavity inside the chamber using a gas supply mechanism, so that the pressure inside the sample membrane electrode is higher than the pressure outside and a stable pressure difference is formed. The robotic arm grasps the helium leak detector and performs a full-area sniffing on the side of the sample membrane electrode facing outwards to find leaks, and records the leakage rate of each leak point.

[0017] In conjunction with the second aspect, in one embodiment, the airtightness testing system further includes a controller for receiving the leakage rate from a helium leak detector and for controlling the movement of a robotic arm. The robotic arm grasps the helium leak detector and performs a full-area sniffing to locate leaks on the side of the sample membrane electrode facing outwards, including: The controller uses a robotic arm to drive the helium leak detector to move in a serpentine pattern on the side of the sample membrane electrode facing outwards, sniffing at equal intervals row by row or column by column according to the design. During the detection process, when the real-time leakage rate of the helium leak detector is greater than zero, the controller reduces the step distance between adjacent rows or columns until the leakage rate reaches its maximum value, thus locating the leak point.

[0018] The beneficial effects of the technical solutions provided in this application include at least the following: 1. The airtightness testing system of this application has a simple structure, mainly consisting of a robotic arm and a helium leak detector. A stable pressure difference is formed by the pressure inside the sample membrane electrode being higher than the pressure outside. The robotic arm and helium leak detector are used to perform a full-area sniffing of the outward-facing side of the sample membrane electrode to find leaks, determine whether a leak exists, and locate the leak point (the location with the highest leakage rate). Simultaneously, the size of the leak can be determined based on the leakage rate of each leak point. The entire process only requires the robotic arm to drive the helium leak detector for full-area sniffing, making it simple to operate and possessing high feasibility and reliability. Compared to the three traditional methods, this application is more precise, not only locating the leak point but also comparing its size, which provides experimental data for evaluating the uniformity of catalyst coating and analyzing the failure mechanism of the membrane electrode. Furthermore, in the airtightness testing system of this application, the gas supply mechanism introduces helium and uses helium to form a stable pressure difference. Helium is safe and stable, and its molecular size is smaller than that of other media such as nitrogen and water vapor, resulting in higher accuracy in airtightness detection.

[0019] 2. The airtightness testing system of this application has a controller that receives the leakage rate from a helium leak detector and is also used to control the robotic arm to move row by row or column by column according to the design interval. When the real-time leakage rate is greater than zero, the step distance between adjacent rows or columns is reduced, which can detect the leak first and locate the leak with high precision after the leak is detected. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A simplified schematic diagram of the membrane electrode airtightness testing system provided in the embodiments of this application; Figure 2 A schematic diagram of the tooling fixture provided in the embodiments of this application; Figure 3 for Figure 2 Top view; In the figure: 10, sample membrane electrode; 1, helium storage bottle; 2, pressure reducing valve; 3, pressure gauge; 4, tooling fixture; 5, helium leak detector; 6, manual switch valve; 41, chamber; 42, clamping assembly; 421, plate frame; 411, inlet; 412, outlet. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0023] This application provides a fuel cell membrane electrode airtightness testing system, which can conveniently and efficiently determine whether the membrane electrode is leaking, locate the leak point, and estimate the size of the leak point area. This provides more detailed test parameters for the research and development testing of fuel cell stacks.

[0024] Firstly, such as Figure 1 and Figure 2 As shown, this application discloses an embodiment of a gas tightness testing system for a fuel cell membrane electrode assembly. The gas tightness testing system includes a tooling fixture 4, an air supply mechanism, and a testing mechanism.

[0025] The tooling fixture 4 includes a chamber 41 and a clamping assembly 42. The chamber 41 is shell-shaped with an open top and has an internal cavity. The sample membrane electrode 10 is clamped and fixed between the clamping assemblies 42, and the clamping assembly 42 with the sample membrane electrode 10 is sealed and fixed to the top opening of the chamber 41.

[0026] The gas supply mechanism is used to supply helium gas to the cavity inside chamber 41, and to make the pressure inside sample membrane electrode 10 higher than the pressure outside and form a stable pressure difference. After the stable pressure difference is formed, if there is a leak in sample membrane electrode 10, it will leak outward; if there is no leak, it will not leak outward.

[0027] The testing facility includes a helium leak detector 5 and a robotic arm. The robotic arm grasps the helium leak detector 5 and performs a full-area sniffing on the outward-facing side of the sample membrane electrode 10 to find leaks and records the leakage rate of each leak.

[0028] Specifically, the unit of leakage rate is generally Pa·m³ / s. Leakage rate is essentially a special unit of flow rate, and it takes into account the pressure factor.

[0029] The airtightness testing system of this application has a simple structure, mainly consisting of a robotic arm and a helium leak detector 5. A stable pressure difference is formed on the inner side of the sample membrane electrode 10 where the pressure is higher than the outer side. The robotic arm and the helium leak detector 5 are used to perform a full-area sniffing of the outer side of the sample membrane electrode 10 to find leaks, determine whether a leak exists, and locate the leak point (the location with the highest leakage rate). Simultaneously, the size of the leak can be determined based on the leakage rate of each leak point. The entire process only requires the robotic arm to drive the helium leak detector for full-area sniffing, making it simple to operate and possessing high feasibility and reliability. Compared to the three traditional methods, this application is more precise, not only locating the leak point but also comparing its size. This provides experimental data for evaluating the uniformity of catalyst coating and analyzing the failure mechanism of the membrane electrode.

[0030] Furthermore, in the airtightness testing system of this application, the gas supply mechanism introduces helium and uses helium to form a stable pressure difference. Helium is safe and stable, and the volume of helium molecules is smaller than that of other media such as nitrogen and water vapor, resulting in higher accuracy in airtightness testing.

[0031] Furthermore, in one embodiment, the helium leak detector 5 is calibrated beforehand using several standard leak holes to determine the leakage rate. During actual testing, the measured leakage rate corresponds to the estimated area of ​​the leak point.

[0032] In the airtightness testing system of this application, the leakage rate of the helium leak detector 5 must be calibrated and measured by a standard leak hole before its leakage rate reading can be accepted. Since the leakage rate of the helium detector has been calibrated by a standard leak hole, the area of ​​the membrane electrode leak point can be estimated by the magnitude of the leakage rate.

[0033] Furthermore, in one embodiment, the robotic arm drives the helium leak detector 5 to move in a serpentine pattern along the outward-facing side of the sample membrane electrode 10, probing row by row or column by column at equal intervals according to a set distance. Specifically, the outward-facing side of the sample membrane electrode 10 is divided into several rows or columns, and each row (corresponding to...) is... Figure 3 (Central X direction) or column by column (corresponding to) Figure 3 (Y-direction) sniffing, advancing a set distance at equal intervals each time. During the detection process, when the real-time leakage rate of the helium leak detector 5 is greater than zero, the surrounding area is gradually probed until the leakage rate reaches its maximum value, thus locating the leak point. Specifically, the maximum leakage rate reached is the actual leakage rate of that leak point.

[0034] Preferably, the precision size of the sniffing at equal intervals along each row or column is greater than the precision size of the sniffing after the leakage rate is found to be greater than zero. For example, the precision size of the sniffing at equal intervals along each row or column is 2 mm, that is, the spacing between adjacent rows or adjacent columns is 1 mm; while the precision size of the sniffing after the leakage rate is found to be greater than zero is 0.1 mm, that is, the spacing between adjacent rows or adjacent columns is 0.1 mm.

[0035] In actual testing, the helium leak detector 5 will inevitably appear around the leak point first (coarse detection process), and then move closer to the exact center of the leak point. Therefore, when it appears around the leak point, i.e., the real-time leakage rate is greater than zero, the movement size is reduced, and further gradual detection is performed (localization process).

[0036] Furthermore, in one embodiment, the airtightness testing system also includes a vernier caliper, which is used to measure the XY coordinates of the leak point on the outward-facing side of the sample membrane electrode 10 after locating the leak point.

[0037] The airtightness testing system of this application accurately measures the XY coordinates of the leak point on the outward-facing side of the sample membrane electrode 10 using vernier calipers, providing more detailed test parameters for the research and development testing of fuel cell stacks.

[0038] Furthermore, in one embodiment, the airtightness testing system also includes a controller, which is used to receive the leakage rate of the helium leak detector 5, and to control the robotic arm to move row by row or column by column according to the design interval, and to reduce the step distance between adjacent rows or adjacent columns when the real-time leakage rate is greater than zero.

[0039] Preferably, during the coarse probing process, the step distance between adjacent rows or adjacent columns is 1 mm, and during the positioning process, the step distance between adjacent rows or adjacent columns is 0.1 mm.

[0040] The airtightness testing system of this application has a controller that receives the leakage rate from the helium leak detector 5 and controls the robotic arm to move row by row or column by column according to the design interval. When the real-time leakage rate is greater than zero, the step distance between adjacent rows or columns is reduced, which can detect the leak first and locate the leak with high precision after the leak is detected.

[0041] Furthermore, in one embodiment, the clamping assembly 42 includes a plate frame 421 and a filter screen, with the filter screen, sample membrane electrode 10, and plate frame 421 arranged sequentially from the top surface of the chamber 41 upwards. The filter screen and plate frame 421 tightly clamp the sample membrane electrode 10 in the middle.

[0042] The plate frame 421 presses and seals the filter screen and sample membrane electrode 10 to the top opening of the chamber 41, so that a sealed cavity is formed inside the chamber 41.

[0043] like Figure 3 As shown, specifically, the clamping assembly 42 also includes several screws. The plate frame 421 presses and seals the filter screen and sample membrane electrode 10 to the top opening of the chamber 41 by several screws. Several screws pass through the filter screen and the periphery of the plate frame 421 and are fixed to the pre-reserved threaded holes at the top opening of the chamber 41.

[0044] Preferably, the anode side of the sample membrane electrode 10 faces outward and the cathode side faces inward; a stable pressure difference of more than 5 kPa is formed between the cathode side and the anode side, and the value of the pressure difference is given by the pressure difference between the anode and cathode when the stack is running.

[0045] Furthermore, in one embodiment, chamber 41 includes an air inlet 411 and an air outlet 412.

[0046] The gas supply mechanism includes a helium storage cylinder 1, a pressure reducing valve 2, a pressure gauge 3, and a manual switch valve 6. The outlet of the helium storage cylinder 1 is connected in sequence to the pressure reducing valve 2, the pressure gauge 3, and the inlet 411 via a pipe. The outlet 412 is connected to the manual switch valve 6 via a pipe. The pressure reducing valve 2 is used to adjust the pressure inside the sample membrane electrode 10.

[0047] Specifically, the airtightness testing system of this application adjusts the pressure inside the sample membrane electrode 10 through the pressure reducing valve 2 and displays the pressure inside the sample membrane electrode 10 through the pressure gauge 3, which meets the pressure difference conditions required for various tests and can be displayed intuitively and clearly through the pressure gauge.

[0048] Furthermore, the controller can also control the pressure reducing valve and adjust it as needed.

[0049] During the actual test, the manual switch valve 6 was in the normally closed state. After the entire test was completed, the helium storage cylinder 1 was closed and the manual switch valve 6 was opened.

[0050] In practical application, the airtightness testing system of this application was used to test eight sample membrane electrodes 10. The test results are shown in Table 1.

[0051] Table 1

[0052] The XY axis and coordinate far point settings are shown in [link to settings]. Figure 3 As shown.

[0053] Secondly, this application discloses a testing method based on the above-mentioned airtightness testing system, comprising the following steps: The sample membrane electrode 10 is held by the clamping assembly 42, and the clamping assembly 42 with the sample membrane electrode 10 is sealed and fixed to the top opening of the chamber 41. Helium gas is introduced into the cavity inside chamber 41 by a gas supply mechanism, so that the pressure inside the sample membrane electrode 10 is higher than the pressure outside and a stable pressure difference is formed. The robotic arm grasps the helium leak detector 5 and performs a full-area sniffing on the outward-facing side of the sample membrane electrode 10 to find leaks, and records the leakage rate of each leak point.

[0054] Regarding the testing method, in one embodiment, the airtightness testing system further includes a controller. The controller is used to receive the leakage rate of the helium leak detector 5 and to control the movement of the robotic arm. The robotic arm grasps the helium leak detector 5 and performs a full-area sniffing to find leaks on the outward-facing side of the sample membrane electrode 10, including: The controller drives the helium leak detector 5 to move in a serpentine pattern on the outward-facing side of the sample membrane electrode 10 via a robotic arm, probing each row or column at equal intervals according to the design. During the detection process, when the real-time leakage rate of the helium leak detector 5 is greater than zero, the controller reduces the step distance between adjacent rows or columns until the leakage rate reaches its maximum value, thus locating the leak point.

[0055] Regarding the testing method, in one embodiment, the clamping assembly 42 includes a plate frame 421 and a filter screen. The filter screen, the sample membrane electrode 10, and the plate frame 421 are arranged sequentially from the top surface of the chamber 41 upwards. The plate frame 421 presses and seals the filter screen and the sample membrane electrode 10 to the top opening of the chamber 41 with several screws. The chamber 41 includes an inlet 411 and an outlet 412; the gas supply mechanism includes a helium storage cylinder 1, a pressure reducing valve 2, a pressure gauge 3, and a manual switch valve 6. The outlet of the helium storage cylinder 1 is connected to the pressure reducing valve 2, the pressure gauge 3, and the inlet 411 in sequence through a pipe. The outlet 412 is connected to the manual switch valve 6 through a pipe. The manual switch valve 6 is normally closed and is opened and closed after the test is completed.

[0056] Helium gas is introduced into the internal cavity of chamber 41 using a gas supply mechanism, and the pressure inside the sample membrane electrode 10 is made higher than the pressure outside to form a stable pressure difference, including: Open helium storage cylinder 1 to output helium, and adjust pressure reducing valve 2 so that the pressure in pressure gauge 3 is 5 kPa higher than the atmospheric pressure during the test, that is, the pressure on the cathode side of the membrane electrode is 5 kPa higher than the pressure on the anode side.

[0057] The testing methods also include: After the test is completed, close the helium storage cylinder 1 and open the hand valve 6 to release the helium in the test pipeline.

[0058] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0059] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A system for testing the airtightness of a fuel cell membrane electrode assembly, characterized in that, Include: The tooling fixture (4) includes a chamber (41) and a clamping assembly (42). The chamber (41) is shell-shaped and open at the top. The clamping assembly (42) clamps and seals the sample membrane electrode (10) to the top opening of the chamber (41). The gas supply mechanism is used to supply helium gas to the cavity inside the chamber (41) and make the pressure inside the sample membrane electrode (10) higher than the pressure outside and form a stable pressure difference; The testing facility includes a helium leak detector (5) and a robotic arm. The robotic arm grasps the helium leak detector (5) and performs a full-area sniffing to find leaks on the outward-facing side of the sample membrane electrode (10), and records the leakage rate of each leak.

2. The gas tightness testing system for a fuel cell membrane electrode as described in claim 1, characterized in that: The helium leak detector (5) is calibrated in advance through several standard leak holes to determine the leakage rate. During actual testing, the leakage rate is measured to correspond to the estimated area of ​​the leak point.

3. The gas tightness testing system for a fuel cell membrane electrode as described in claim 1, characterized in that: The robotic arm drives the helium leak detector (5) to move in a serpentine pattern on the outward side of the sample membrane electrode (10), probing row by row or column by column at equal intervals according to the set distance. During the detection process, when the real-time leakage rate of the helium leak detector (5) is greater than zero, it will gradually sniff around until the leakage rate reaches its maximum value and locate the leak point.

4. The gas tightness testing system for a fuel cell membrane electrode as described in claim 3, characterized in that: The airtightness testing system also includes a vernier caliper, which is used to measure the XY coordinates of the leak point on the outward side of the sample membrane electrode (10) after locating the leak point.

5. The gas tightness testing system for a fuel cell membrane electrode as described in claim 3, characterized in that: The airtightness testing system also includes a controller, which is used to receive the leakage rate of the helium leak detector (5), and to control the robotic arm to move row by row or column by column according to the design interval, and to reduce the step distance between adjacent rows or columns when the real-time leakage rate is greater than zero.

6. The gas tightness testing system for a fuel cell membrane electrode as described in claim 1, characterized in that: The clamping assembly (42) includes a plate frame (421) and a filter screen. The filter screen, sample membrane electrode (10) and plate frame (421) are arranged sequentially from the top surface of the chamber (41) upwards. The plate frame (421) presses and seals the filter screen and sample membrane electrode (10) to the top opening of the chamber (41) by a number of screws.

7. The gas tightness testing system for a fuel cell membrane electrode as described in claim 1, characterized in that: The anode side of the sample membrane electrode (10) faces outward, and the cathode side faces inward; a stable pressure difference of more than 5 kPa is formed between the cathode side and the anode side.

8. The gas tightness testing system for a fuel cell membrane electrode as described in claim 1, characterized in that: The chamber (41) includes an inlet (411) and an outlet (412); the gas supply mechanism includes a helium storage cylinder (1), a pressure reducing valve (2), a pressure gauge (3) and a manual switch valve (6). The outlet of the helium storage cylinder (1) is connected to the pressure reducing valve (2), the pressure gauge (3) and the inlet (411) in sequence through a pipe. The outlet (412) is connected to the manual switch valve (6) through a pipe. The manual switch valve (6) is normally closed and is opened and closed after the test is completed.

9. A testing method based on the airtightness testing system of claim 1, characterized in that, Includes the following steps: The sample membrane electrode (10) is held by the clamping assembly (42), and the clamping assembly (42) with the sample membrane electrode (10) is sealed and fixed to the top opening of the chamber (41); Helium gas is introduced into the cavity inside the chamber (41) by a gas supply mechanism, so that the pressure inside the sample membrane electrode (10) is higher than the pressure outside and a stable pressure difference is formed. The robotic arm grasps the helium leak detector (5) and performs a full-area sniffing on the outward-facing side of the sample membrane electrode (10) to find leaks and records the leakage rate of each leak.

10. The test method as described in claim 9, characterized in that, The airtightness testing system also includes a controller, which is used to receive the leakage rate of the helium leak detector (5) and to control the movement of the robotic arm. The robotic arm grasps the helium leak detector (5) and performs a full-area sniffing to find leaks on the outward-facing side of the sample membrane electrode (10), including: The controller drives the helium leak detector (5) to move in a serpentine pattern on the outward side of the sample membrane electrode (10) via a robotic arm, and sniffs at equal intervals row by row or column by column according to the design intervals. During the detection process, when the real-time leakage rate of the helium leak detector (5) is greater than zero, the controller reduces the step distance between adjacent rows or columns until the leakage rate is detected to reach the maximum value, thus locating the leak point.

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