Method for detecting the air tightness of a fuel cell stack

Abstract

The application provides a fuel cell stack airtightness detection method. The fuel cell stack airtightness detection method controls a first leakage tester, a second leakage tester and three test branches of a fuel cell stack airtightness detection system to work, so that the first leakage tester, the second leakage tester and the three test branches can form air-fuel-to-liquid series leakage detection flow paths, air-to-liquid series leakage detection flow paths, fuel-to-liquid series leakage detection flow paths, and an external leakage detection flow path. The fuel cell stack airtightness detection method controls a gas supply assembly to supply gas to the air-fuel-to-liquid series leakage detection flow paths, the air-to-liquid series leakage detection flow paths, the fuel-to-liquid series leakage detection flow paths, and the external leakage detection flow path. The fuel cell stack airtightness detection method can quickly and efficiently detect the airtightness of the stack and effectively improve the detection efficiency.

Description

Technical Field

[0001] This invention relates to the field of fuel cell system technology, and in particular to a method for detecting the airtightness of fuel cell stacks. Background Technology

[0002] A fuel cell is a power generation device that directly converts the chemical energy in fuel into electrical energy through an electrochemical reaction. Because the only product of the electrochemical reaction is water, it causes minimal environmental pollution. Furthermore, fuel cells operate without relative mechanical movement, resulting in low noise. Moreover, fuel cells have high theoretical efficiency, making them widely used in numerous fields such as stationary power supplies, portable power supplies, transportation, aerospace, and marine propulsion. They possess broad application prospects and enormous market potential.

[0003] Because the cavities, fuel chambers, and water chambers formed in the fuel cell stack are small in volume and have low leakage values, an airtightness test must be performed on the fuel cell stack before it can be put into normal use. Currently, while existing fuel cell stack airtightness testing methods can detect the airtightness of the stack, their efficiency is low. Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting the airtightness of fuel cell stacks, so as to solve the problem of low efficiency in the existing fuel cell stack airtightness detection methods.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A method for detecting the airtightness of a fuel cell stack is provided. The stack includes an air flow path, a fuel flow path, and a coolant flow path. The fuel cell stack airtightness detection system includes a gas supply assembly, a first leak tester, a second leak tester, and three test branches. The first and second leak testers are connected in parallel and both are connected to the output end of the gas supply assembly, which supplies gas. The output end of the first leak tester has two test branches, which are connected in parallel, with the first end of each branch connected to the first leak tester. The output of the instrument has two test branches, the second ends of which are respectively connected to the input of the air flow path and the input of the fuel flow path. The output of the second leak tester has one test branch, the first end of which is connected to the output of the second leak tester, and the second end of which is connected to the input of the coolant flow path. The test branch is configured to selectively connect the first end and the second end, or to connect the second end to the outside. The outputs of the air flow path, the fuel flow path, and the coolant flow path are all blocked.

[0007] The method for detecting the airtightness of the fuel cell stack includes:

[0008] Perform air-to-liquid leakage detection: control the gas supply assembly to supply gas to the first leakage tester; control the connection between the first and second ends of the two test branches located at the output end of the first leakage tester; control the first leakage tester to supply gas to the two test branches located at the output end of the first leakage tester, stop the gas supply and maintain pressure after a first set time; after a second set time, control the connection between the first and second ends of the test branch located at the output end of the second leakage tester, control the second leakage tester to test for leakage, and record the first leakage value.

[0009] Preferably, the fuel cell stack airtightness testing method further includes:

[0010] Perform air-to-liquid cross-leak detection: Control the air supply assembly to supply air to the first leak tester; control the connection between the first end and the second end of one of the two test branches corresponding to the air flow path at the output end of the first leak tester; control the first leak tester to supply air to one of the two test branches corresponding to the air flow path at the output end of the first leak tester, stop the air supply and maintain pressure after the first set time; after the second set time, control the connection between the first end and the second end of the test branch at the output end of the second leak tester, control the second leak tester to test for cross-leakage, and record the third cross-leakage value;

[0011] And / or, perform fuel-to-liquid cross-leak detection: control the gas supply assembly to supply gas to the first leak tester; control the connection of the first end and the second end of one of the two test branches corresponding to the fuel flow path in the output of the first leak tester; control the first leak tester to supply gas to one of the two test branches corresponding to the fuel flow path in the output of the first leak tester, stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the first end and the second end of the test branch in the output of the second leak tester, control the second leak tester to test for cross-leakage, and record the fourth cross-leakage value.

[0012] Preferably, the fuel cell stack airtightness testing method further includes:

[0013] Simultaneously perform external leakage detection of coolant flow path, fuel flow path, and air flow path: control the air supply assembly to supply air to both the first and second leakage testers; control the connection between the first and second ends of the two test branches located at the output end of the first leakage tester, and control the connection between the first and second ends of the test branch located at the output end of the second leakage tester; control the first leakage tester to supply air to the two test branches located at the output end of the first leakage tester and maintain pressure, and simultaneously control the second leakage tester to supply air to the test branch located at the output end of the second leakage tester and maintain pressure; after a second set time period, control the second end of one of the two test branches located at the output end of the first leakage tester to connect to the outside, control the first leakage tester to test for external leakage and record the first external leakage value, and simultaneously control the second leakage tester to test for external leakage of the coolant flow path and record the second external leakage value.

[0014] Preferably, the fuel cell stack airtightness testing system further includes a connecting branch, the third end of which is connected to the output end of the second leakage tester, and the fourth end of which is connected to the second end of one of the two test branches located at the output end of the first leakage tester. The connecting branch is configured to selectively connect the third end and the fourth end, or to connect the fourth end to the outside.

[0015] Preferably, when the fourth end of the connecting branch is connected to the second end of one of the two test branches corresponding to the fuel flow path located at the output end of the first leakage tester, the fuel cell stack airtightness detection method further includes:

[0016] Perform air-to-fuel leakage detection: control the gas supply assembly to supply gas to the first leakage tester; control the connection of the first and second ends of the two test branches corresponding to one of the air flow paths at the output end of the first leakage tester; control the first leakage tester to supply gas to one of the two test branches corresponding to the air flow path at the output end of the first leakage tester, stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the third and fourth ends of the connected branch, control the second leakage tester to test for leakage, and record the second leakage value.

[0017] Preferably, both the output terminals of the first and second leak testers are provided with a first verification branch, and the first verification branch is connected in parallel with the test branch. The first verification branch includes a fourth two-position three-way control valve and a first leak pipe. The input terminal of the fourth two-position three-way control valve is used to connect with the output terminal of the first or second leak tester. The output terminal of the fourth two-position three-way control valve is connected to one end of the first leak pipe, the other end of the first leak pipe is blocked, and the connecting end of the fourth two-position three-way control valve is blocked.

[0018] Preferably, the fuel cell stack airtightness testing method further includes:

[0019] Perform air-to-liquid leakage verification: Control the gas supply assembly to supply gas to the first leakage tester; control the connection between the first and second ends of the two test branches located at the output end of the first leakage tester; control the first leakage tester to supply gas to the two test branches located at the output end of the first leakage tester, stop the gas supply after a first set time and maintain pressure; after a second set time, control the connection between the first and second ends of the test branch located at the output end of the second leakage tester, control the connection between the input and output ends of the fourth two-position three-way control valve located at the output end of the second leakage tester; control the second leakage tester to test and record the first leakage verification value; determine whether the first leakage value is accurate based on the first leakage verification value.

[0020] Preferably, the fuel cell stack airtightness testing method further includes:

[0021] Perform air-to-liquid leakage verification: Control the air supply assembly to supply air to the first leakage tester; control the connection of the first and second ends of the two test branches corresponding to one of the air flow paths at the output end of the first leakage tester; control the first leakage tester to supply air to one of the two test branches corresponding to the air flow path at the output end of the first leakage tester, stop the air supply and maintain pressure after the first set time; after the second set time, control the connection of the first and second ends of the test branch at the output end of the second leakage tester, and control the connection of the input and output ends of the fourth two-position three-way control valve at the output end of the second leakage tester; control the second leakage tester to test and record the third leakage verification value; determine whether the third leakage value is accurate based on the third leakage verification value;

[0022] And / or, perform a fuel-to-liquid leakage check: control the gas supply assembly to supply gas to the first leakage tester; control the connection of the first end and the second end of one of the two test branches corresponding to the fuel flow path in the output of the first leakage tester; control the first leakage tester to supply gas to one of the two test branches corresponding to the fuel flow path in the output of the first leakage tester, stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the first end and the second end of the test branch in the output of the second leakage tester, control the connection of the input end and the output end of the fourth two-position three-way control valve in the output of the second leakage tester; control the second leakage tester to test and record the fourth leakage check value; determine whether the fourth leakage value is accurate based on the fourth leakage check value.

[0023] Preferably, the fuel cell stack airtightness testing method further includes:

[0024] Simultaneously perform external leakage verification of the coolant flow path, and one of the external leakage verifications of the fuel flow path and the air flow path: control the air supply assembly to supply air to both the first and second leakage testers; control the connection of the first and second ends of the two test branches located at the output end of the first leakage tester; control the connection of the first and second ends of the test branch located at the output end of the second leakage tester; control the first leakage tester to supply air to the two test branches located at the output end of the first leakage tester and maintain pressure, and simultaneously control the second leakage tester to supply air to the test branch located at the output end of the second leakage tester and maintain pressure; after a second set time, control the connection of the input and output ends of the two fourth two-position three-way control valves, and control the connection of the second end of one of the two test branches located at the output end of the first leakage tester to the outside; control the first leakage tester to test and record the first external leakage verification value, and simultaneously control the second leakage tester to test and record the second external leakage verification value; determine whether the first external leakage value is accurate based on the first external leakage verification value, and determine whether the second external leakage value is accurate based on the second external leakage verification value.

[0025] Preferably, the specific steps for determining whether the first string leakage value is accurate based on the first string leakage check value include:

[0026] Calculate whether the deviation rate is within the set deviation rate range; wherein, the deviation rate = |first string leak value -first string leak check value -amount of gas leaked from the first leak pipe| / first string leak value;

[0027] If the deviation rate is within the set deviation rate range, it indicates that the first string of missing values ​​is accurate;

[0028] If the deviation rate is not within the set deviation rate range, it indicates that the first string of missing values ​​is inaccurate.

[0029] Preferably, the output end of the first leakage tester is further provided with a second verification branch. The fifth end of the second verification branch is connected to the output end of the first leakage tester, and the sixth end of the second verification branch is connected to the connecting branch. The second verification branch is provided with a second leakage pipe and two fifth two-position three-way control valves. The two ends of the second leakage pipe are respectively connected to the output ends of the two fifth two-position three-way control valves. The input end of one of the fifth two-position three-way control valves is connected to the fifth end of the second verification branch, and the connecting end of one of the fifth two-position three-way control valves is blocked. The input end of the other fifth two-position three-way control valve is connected to the sixth end of the second verification branch, and the connecting end of the other fifth two-position three-way control valve is blocked.

[0030] Preferably, the fuel cell stack airtightness testing method further includes:

[0031] Perform air-to-fuel leakage verification: Control the gas supply assembly to supply gas to the first leakage tester; control the connection of the first and second ends of the two test branches corresponding to one of the air flow paths at the output end of the first leakage tester; control the first leakage tester to supply gas to one of the two test branches corresponding to the air flow path at the output end of the first leakage tester, stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the third and fourth ends of the connected branch, and control the connection of the input and output ends of the other fifth two-position three-way control valve; control the second leakage tester to test and record the second leakage verification value; determine whether the second leakage value is accurate based on the second leakage verification value.

[0032] The beneficial effects of this invention are:

[0033] This invention provides a method for detecting the airtightness of a fuel cell stack. The stack includes an air flow path, a fuel flow path, and a coolant flow path. The fuel cell stack airtightness detection system includes a gas supply assembly, a first leak tester, a second leak tester, and three test branches. When performing air-fuel to liquid leakage detection, the gas supply assembly supplies gas to the first leak tester. The first and second ends of the two test branches located at the output of the first leak tester are connected. The first leak tester supplies gas to the two test branches located at its output. After a first set time, when the gas pressure in the two test branches, the air flow path, and the fuel flow path all reach a certain pressure value, the gas supply is stopped and the pressure is maintained. After maintaining the pressure for a period of time, the first and second ends of the test branch located at the output of the second leak tester are connected, thus connecting the coolant flow path and the second leak tester. The second leak tester is then used to test for leakage. This method effectively improves the efficiency of air-fuel to liquid leakage detection.

[0034] Therefore, by controlling the fuel cell stack airtightness detection system through this fuel cell stack airtightness detection method, the airtightness of the stack can be detected quickly and efficiently compared with the existing technology, effectively improving the detection efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a fuel cell stack airtightness testing system provided in a specific embodiment of the present invention;

[0036] Figure 2 This is a diagram showing the relationship between the fuel cell stack airtightness testing method provided in a specific embodiment of the present invention.

[0037] In the picture:

[0038] 100. Fuel cell stack; 110. Air flow path; 120. Fuel flow path; 130. Coolant flow path;

[0039] 1. First Leakage Tester;

[0040] 2. Second leak tester;

[0041] 3. Test branch; 31. First two-position three-way control valve;

[0042] 4. Connecting branch; 41. Second two-position three-way control valve;

[0043] 5. Third two-position three-way control valve;

[0044] 6. First verification branch; 61. Fourth two-position three-way control valve; 62. First leakage pipe;

[0045] 7. Second verification branch; 71. Second leakage pipe; 72. Fifth two-position three-way control valve. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0047] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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 of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0049] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0050] like Figure 1As shown, the present invention provides a fuel cell stack airtightness testing system for testing the airtightness of a fuel cell stack 100. The fuel cell stack airtightness testing system includes a gas supply assembly, a first leakage tester 1, a second leakage tester 2, and three test branches 3. The first leakage tester 1 and the second leakage tester 2 are connected in parallel and both are connected to the output end of the gas supply assembly, which is used for gas supply. The output end of the first leakage tester 1 has two test branches 3, which are connected in parallel, and the first end of each of the two test branches 3 is connected to the output end of the first leakage tester 1. The second ends of the two test branches 3 are connected to the input ends of the air flow path 110 and the fuel flow path 120, respectively; the output end of the second leak tester 2 is provided with a test branch 3, the first end of the test branch 3 is connected to the output end of the second leak tester 2, and the second end of the test branch 3 is connected to the input end of the coolant flow path 130; the test branch 3 is configured to selectively connect the first end and the second end, or connect the second end to the outside; the output ends of the air flow path 110, the fuel flow path 120 and the coolant flow path 130 are all blocked.

[0051] When performing air-fuel to liquid leakage detection, the air supply assembly is controlled to supply air to the first leakage tester 1; the first and second ends of the two test branches 3 located at the output end of the first leakage tester 1 are connected; the first leakage tester 1 is controlled to supply air to the two test branches 3 located at the output end of the first leakage tester 1. After a first set time, when the air pressure of the two test branches 3, the air pressure of the air flow path 110, and the air pressure of the fuel flow path 120 all reach a certain air pressure value, the air supply is stopped and the pressure is maintained. After maintaining the pressure for a period of time, the first and second ends of the test branch 3 located at the output end of the second leakage tester 2 are connected, so that the coolant flow path 130 is connected to the second leakage tester 2. Then, the second leakage tester 2 is used to test whether there is leakage, which can effectively improve the efficiency of air-fuel to liquid leakage detection.

[0052] When performing air-to-liquid leakage detection, the air supply assembly is controlled to supply air to the first leakage tester 1; the first and second ends of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1 are connected; the first leakage tester 1 is controlled to supply air to one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1; after a first set time, the air pressure of the test branch 3 corresponding to the air flow path 110 and the air pressure of the air flow path 110 both reach a certain pressure value, then the air supply is stopped and the pressure is maintained; after maintaining the pressure for a period of time, the first and second ends of the test branch 3 at the output end of the second leakage tester 2 are connected, so that the coolant flow path 130 and the second leakage tester 2 are connected, and then the second leakage tester 2 is controlled to test whether there is leakage, which can effectively improve the efficiency of air-to-liquid leakage detection.

[0053] When performing fuel-to-liquid leakage detection, the gas supply assembly is controlled to supply gas to the first leakage tester 1; the first and second ends of the two test branches 3 corresponding to the fuel flow path 120 at the output end of the first leakage tester 1 are connected; the first leakage tester 1 is controlled to supply gas to the fuel flow path 120 at the output end of the two test branches 3 corresponding to the fuel flow path 120. After a first set time, the gas pressure of the test branch 3 corresponding to the fuel flow path 120 and the gas pressure of the fuel flow path 120 both reach a certain pressure value, then the gas supply is stopped and the pressure is maintained; after maintaining the pressure for a period of time, the first and second ends of the test branch 3 at the output end of the second leakage tester 2 are connected, so that the coolant flow path 130 and the second leakage tester 2 are connected, and then the second leakage tester 2 is controlled to test whether there is a leakage, which can effectively improve the efficiency of fuel-to-liquid leakage detection.

[0054] When performing external leakage detection, simultaneous detection by the first leakage tester 1 and the second leakage tester 2 can further improve the efficiency of testing the airtightness of the fuel cell stack 100. Specifically, taking simultaneous external leakage detection of the coolant flow path and external leakage detection of the fuel flow path as an example, the air supply assembly is controlled to supply air to both the first leakage tester 1 and the second leakage tester 2; the first and second ends of the two test branches 3 located at the output end of the first leakage tester 1 are connected, and at the same time, the first and second ends of the test branch 3 located at the output end of the second leakage tester 2 are connected; the first leakage tester 1 is controlled to supply air to the two test branches 3 located at the output end of the first leakage tester 1 and maintain pressure, and at the same time, the second leakage tester 2 is controlled to supply air to the two test branches 3 located at the output end of the first leakage tester 1 and maintain pressure. The test branch 3 at the output end of the second leak tester 2 is supplied with air and pressurized. After the pressure is maintained for a certain period of time, the second end of one of the two test branches 3 at the output end of the first leak tester 1, corresponding to the air flow path 110, is connected to the outside, so that the first end and the second end of one of the two test branches 3 at the output end of the first leak tester 1, corresponding to the fuel flow path 120, are kept connected. The first leak tester 1 is controlled to test whether the fuel flow path 120 is leaking externally. At the same time, the second leak tester 2 is controlled to test whether the coolant flow path 130 is leaking externally.

[0055] Therefore, compared with the existing technology, the fuel cell stack air tightness testing system has a simple structure and fewer parts, which effectively reduces the production cost of the fuel cell stack air tightness testing system and can effectively improve the testing efficiency of the fuel cell stack air tightness testing system for testing the air tightness of the stack 100.

[0056] It is understandable that the two ends of test branch 3 are the first end and the second end, respectively.

[0057] The test branch 3 is equipped with a first two-position three-way control valve 31. The input end of the first two-position three-way control valve 31 is connected to the first end, the output end of the first two-position three-way control valve 31 is connected to the second end, and the connecting end of the first two-position three-way control valve 31 is connected to the outside. This configuration allows the test branch 3 to selectively connect the first end and the second end, or to connect the second end to the outside.

[0058] The fuel cell stack airtightness testing system also includes a connecting branch 4. The third end of the connecting branch 4 is connected to the output end of the second leak tester 2, and the fourth end of the connecting branch 4 is connected to the second end of one of the two test branches 3 located at the output end of the first leak tester 1. The connecting branch 4 is configured to selectively connect the third and fourth ends, or to connect the fourth end to the outside. It can be understood that the two ends of the connecting branch 4 are the third and fourth ends, respectively.

[0059] Specifically, in this embodiment, taking the connection of the fourth end of the connecting branch 4 with the second end of one of the two test branches 3 corresponding to the fuel flow path 120 at the output end of the first leak tester 1 as an example, when performing air-to-fuel leakage detection, the gas supply component is controlled to supply gas to the first leak tester 1; the first end and the second end of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leak tester 1 are connected; the first leak tester 1 is controlled to supply gas to one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leak tester 1, and after a first set time, the gas pressure of the test branch 3 corresponding to the air flow path 110 and the gas pressure of the air flow path 110 both reach a certain pressure value, then the gas supply is stopped and the pressure is maintained; after maintaining the pressure for a period of time, the third and fourth ends of the connecting branch 4 are connected, so that the fuel flow path 120 and the second leak tester 2 are connected through the connecting branch 4, and then the second leak tester 2 is controlled to test whether there is leakage, which can effectively improve the efficiency of air-to-fuel leakage detection.

[0060] Specifically, the connecting branch 4 is equipped with a second two-position three-way control valve 41. The input end of the second two-position three-way control valve 41 is connected to the fourth end, the output end of the second two-position three-way control valve 41 is connected to the third end, and the connecting end of the second two-position three-way control valve 41 is connected to the outside. This configuration allows the connecting branch 4 to selectively connect the third and fourth ends, or connect the fourth end to the outside.

[0061] Specifically, the fuel cell stack airtightness testing system also includes three third two-position three-way control valves 5, each corresponding to one of the three test branches 3. The input end of the third two-position three-way control valve 5 is connected to the test branch 3 and is located between the first two-position three-way control valve 31 and the fuel cell stack 100. The output end of the third two-position three-way control valve 5 is connected to the outside, while the connection end of the second two-position three-way control valve 41 is blocked. It is understood that the three third two-position three-way control valves 5 are all located close to the fuel cell stack 100. This arrangement allows the gas within the fuel cell stack airtightness testing system and the gas within the fuel cell stack 100 to be discharged to the outside after the airtightness testing or calibration of the fuel cell stack 100 is completed.

[0062] The first leakage tester 1 and the second leakage tester 2 each have a first verification branch 6 at their output ends, and the first verification branch 6 is connected in parallel with the test branch 3. The first verification branch 6 includes a fourth two-position three-way control valve 61 and a first leakage pipe 62. The input end of the fourth two-position three-way control valve 61 is connected to either the output end of the first leakage tester 1 or the output end of the second leakage tester 2. The output end of the fourth two-position three-way control valve 61 is connected to one end of the first leakage pipe 62, while the other end of the first leakage pipe 62 is blocked, and the connecting end of the fourth two-position three-way control valve 61 is also blocked. Specifically, the first leakage pipe 62 has a first leakage hole that communicates with the outside, allowing gas entering the first leakage pipe 62 to be discharged to the outside through the first leakage hole.

[0063] Specifically, when performing a cross-leak test from air to fuel, the air supply assembly is controlled to supply air to the first leak tester 1; the first and second ends of the two test branches 3 located at the output of the first leak tester 1 are connected; the first leak tester 1 is controlled to supply air to the two test branches 3 located at the output of the first leak tester 1; after a first set time, when the air pressure in the two test branches 3, the air pressure in the air flow path 110, and the fuel flow path 120 all reach a certain pressure value, the air supply is stopped and the pressure is maintained; after maintaining the pressure for a period of time, the control is activated on the second leak tester. The first and second ends of the test branch 3 at the output end of 2 are connected, connecting the coolant flow path 130 and the second leak tester 2. This connects the input and output ends of the fourth two-position three-way control valve 61 located at the output end of the second leak tester 2, allowing a portion of the gas flowing to the input end of the fourth two-position three-way control valve 61 to be discharged to the outside. Then, the second leak tester 2 is controlled to test, and the accuracy of the leakage value measured during the air-fuel to liquid leakage detection is verified based on the amount of gas leaking from the first leakage hole and the measured leakage verification value. This allows the fuel cell stack airtightness testing system to both test the airtightness of the stack 100 and verify the accuracy of the airtightness test, thereby further improving the performance of the fuel cell stack airtightness testing system and further reducing costs.

[0064] When performing an air-to-liquid leakage test, the air supply assembly is controlled to supply air to the first leakage tester 1; the first and second ends of the two test branches 3 corresponding to one of the air flow paths 110 at the output of the first leakage tester 1 are connected; the first leakage tester 1 is controlled to supply air to one of the two test branches 3 corresponding to the air flow path 110 at the output of the first leakage tester 1, and after a first set time, the air pressure of the test branch 3 corresponding to the air flow path 110 and the air pressure of the air flow path 110 both reach a certain pressure value, then the air supply is stopped and the pressure is maintained; after maintaining the pressure for a period of time, the second leakage tester 1 is controlled to supply air to the first leakage tester 1. The first and second ends of the test branch 3 at the output end of the leak tester 2 are connected, so that the coolant flow path 130 and the second leak tester 2 are connected. The input and output ends of the fourth two-position three-way control valve 61 set at the output end of the second leak tester 2 are connected, so that a portion of the gas flowing to the input end of the fourth two-position three-way control valve 61 can be discharged to the outside. Then, the second leak tester 2 is controlled to test, and the accuracy of the measured leakage value during the air-to-liquid leakage detection is verified based on the amount of gas leaked from the first leakage hole and the measured leakage verification value, so as to realize the accuracy of the air-to-liquid leakage detection.

[0065] When performing a fuel-to-liquid leakage test, the control gas supply assembly supplies gas to the first leakage tester 1; the control connects the first and second ends of the two test branches 3 at the output of the first leakage tester 1, corresponding to one of the fuel flow paths 120; the control supplies gas to one of the two test branches 3 at the output of the first leakage tester 1, corresponding to one of the fuel flow paths 120, and after a first set time, the gas pressure of the test branch 3 corresponding to the fuel flow path 120 and the gas pressure of the fuel flow path 120 both reach a certain pressure value, then the gas supply stops and the pressure is maintained; after maintaining the pressure for a period of time, the control connects the second... The first and second ends of the test branch 3 at the output end of the leak tester 2 are connected, so that the coolant flow path 130 and the second leak tester 2 are connected. The input and output ends of the fourth two-position three-way control valve 61 set at the output end of the second leak tester 2 are connected, so that a portion of the gas flowing to the input end of the fourth two-position three-way control valve 61 can be discharged to the outside. Then, the second leak tester 2 is controlled to test, and the accuracy of the cross-leakage value measured when detecting the cross-leakage of the flammable liquid is verified based on the amount of gas leaked from the first leak hole and the measured cross-leakage verification value, so as to realize the accuracy of the cross-leakage detection of the flammable liquid.

[0066] When performing external leakage verification, simultaneous verification by the first leakage tester 1 and the second leakage tester 2 can further improve the accuracy and efficiency of the fuel cell stack airtightness detection system for verifying the airtightness of the stack 100. Specifically, in this embodiment, simultaneous external leakage verification of the coolant flow path 130 and the fuel flow path is taken as an example. The gas supply assembly is controlled to supply gas to both the first leakage tester 1 and the second leakage tester 2; the first and second ends of the two test branches 3 located at the output end of the first leakage tester 1 are connected, and at the same time, the first and second ends of the test branch 3 located at the output end of the second leakage tester 2 are connected; the first leakage tester 1 is controlled to supply gas to the two test branches 3 located at the output end of the first leakage tester 1 and maintain pressure, and at the same time, the second leakage tester 2 is controlled to supply gas to the test branch 3 located at the output end of the second leakage tester 2 and maintain pressure; after maintaining pressure for a certain period of time, the two test branches located at the output end of the first leakage tester 1 are controlled to... The second end of one of the air flow paths 110 in path 3 is connected to the outside, so that the first and second ends of one of the two test branches 3 corresponding to the fuel flow path 120 in the output of the first leak tester 1 are kept connected. The input and output ends of the fourth two-position three-way control valve 61 in the output of the first leak tester 1 are connected, and the first leak tester 1 is then controlled to test. At the same time, the test branch 3 in the output of the second leak tester 2 is kept connected, and the input and output ends of the fourth two-position three-way control valve 61 in the output of the second leak tester 2 are connected, and the second leak tester 2 is then controlled to test. This can verify the accuracy of external leakage detection in the fuel flow path 120, verify the accuracy of external leakage detection in the coolant flow path 130, and further improve the efficiency of external leakage verification. Thus, it can further improve the accuracy and efficiency of verifying the airtightness of the fuel cell stack 100 through this fuel cell stack airtightness detection system.

[0067] The first leak tester 1 has a second verification branch 7 at its output end. The fifth end of the second verification branch 7 is connected to the output end of the first leak tester 1, and the sixth end of the second verification branch 7 is also connected to the output end of the second two-position three-way control valve 41. The second verification branch 7 has a second leak pipe 71 and two fifth-position three-way control valves 72. Both ends of the second leak pipe 71 are connected to the output ends of the two fifth-position three-way control valves 72, respectively. The input end of one fifth-position three-way control valve 72 is connected to the fifth end of the second verification branch 7, and the connecting end of the other fifth-position three-way control valve 72 is blocked. The input end of the other fifth-position three-way control valve 72 is connected to the sixth end of the second verification branch 7, and the connecting end of the other fifth-position three-way control valve 72 is blocked. Specifically, the second leak pipe 71 has a second leak hole that connects to the outside, allowing gas entering the second leak pipe 71 to be discharged to the outside through the second leak hole. It can be understood that the two ends of the second verification branch 7 are the fifth end and the sixth end, respectively.

[0068] Specifically, during air-to-fuel leakage testing, the gas supply assembly is controlled to supply gas to the first leakage tester 1; the first and second ends of the two test branches 3 corresponding to one of the air flow paths 110 at the output of the first leakage tester 1 are connected; the first leakage tester 1 is controlled to supply gas to one of the two test branches 3 corresponding to the air flow path 110 at the output of the first leakage tester 1; after a first set time, the gas pressure of the test branch 3 corresponding to the air flow path 110 and the gas pressure of the air flow path 110 both reach a certain pressure value, and then the gas supply is stopped. Pressure holding; after holding pressure for a period of time, control the connection of the third and fourth ends of the connecting branch 4 to connect the fuel flow path 120 and the second leak tester 2 through the connecting branch 4, control the connection of the input and output ends of another fifth two-position three-way control valve 72 to connect the gas flowing out of the fuel flow path 120 to be discharged to the outside through the second leak hole, and then control the second leak tester 2 to test, and verify the accuracy of the leak value measured when performing air-to-fuel leak detection based on the amount of gas leaked from the second leak hole and the measured leak verification value, so as to realize the accuracy of air-to-fuel leak detection.

[0069] Optionally, there may be multiple second verification branches 7, which are distributed in parallel. In this embodiment, two second verification branches 7 are provided as an example.

[0070] Preferably, the first two-position three-way control valve 31 is a pneumatic two-position three-way control valve. The second two-position three-way control valve 41 is a pneumatic two-position three-way control valve. The third two-position three-way control valve 5 is a pneumatic two-position three-way control valve. The fourth two-position three-way control valve 61 is a pneumatic two-position three-way control valve. The fifth two-position three-way control valve 72 is a pneumatic two-position three-way control valve. Compared with using solenoid valves, this method can further improve the accuracy of the fuel cell stack airtightness detection system in detecting the airtightness of the stack, and can also further improve the accuracy of the airtightness detection results calibrated by the fuel cell stack airtightness detection system. The reason is that the solenoid valve generates heat when energized, and the heat dissipated will heat the gas in the fuel cell stack airtightness detection system through heat conduction. This causes the gas temperature to change during the airtightness detection process or the verification of the accuracy of the airtightness detection results, thus affecting the accuracy of the airtightness detection.

[0071] The specific structure of the gas supply component is existing technology and will not be described in detail here. The specific structures of the first leak tester 1 and the second leak tester 2 are existing technology and will not be described in detail here.

[0072] The present invention also provides a method for detecting the air tightness of a fuel cell stack, which is used to control the above-mentioned fuel cell stack air tightness detection system so as to be able to detect the air tightness of the stack 100, improve the efficiency of detecting the air tightness of the stack 100, verify the accuracy of the air tightness detection results of the stack 100, and improve the efficiency of verifying the accuracy of the air tightness detection results of the stack 100.

[0073] Specifically, in this embodiment, taking the connection of the fourth end of the connecting branch 4 with the second end of one of the two test branches 3 corresponding to the fuel flow path 120 located at the output end of the first leakage tester 1 as an example, the fuel cell stack airtightness testing method is as follows:

[0074] Perform a cross-leak test from air fuel to liquid:

[0075] S110, Control the gas supply component to supply gas to the first leak tester 1.

[0076] S120, the first and second ends of the two test branches 3 located at the output end of the first leak tester 1 are connected. That is, the input and output ends of the first two-position three-way control valve 31 located on the two test branches 3 at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to both the air flow path 110 and the fuel flow path 120.

[0077] S130, control the first leak tester 1 to supply air to the two test branches 3 set at the output end of the first leak tester 1, and stop the air supply and maintain pressure after a first set time.

[0078] Specifically, the first set duration is greater than or equal to 3 seconds.

[0079] In this embodiment, the first set duration is preferably 3 seconds. It can be understood that after 3 seconds of inflation, the air pressure values ​​of the two test branches 3, the air flow path 110 and the fuel flow path 120 set at the output end of the first leakage tester 1 will all reach a certain air pressure value.

[0080] S140. After the second set duration, the first and second ends of the test branch 3 located at the output of the second leak tester 2 are connected, controlling the second leak tester 2 to test for cross-leakage and record the first cross-leakage value. It can be understood that the second set duration is the pressure holding duration. The input and output ends of the first two-position three-way control valve 31 on the test branch 3 located at the output of the second leak tester 2 are connected, so that the first and second ends of the test branch 3 located at the output of the second leak tester 2 are connected, thereby connecting the coolant flow path 130 and the second leak tester 2.

[0081] Specifically, the second set duration is greater than or equal to 15 seconds. In this embodiment, the second set duration is preferably 15 seconds.

[0082] S150. Determine whether the first leakage value is greater than or equal to the set leakage value. If the first leakage value is greater than or equal to the set leakage value, it is preliminarily determined that there is a leakage from air to fuel to liquid. If the first leakage value is less than the set leakage value, it is preliminarily determined that there is no leakage from air to fuel to liquid.

[0083] The string leakage value was set as an empirical value obtained from a large number of previous experiments.

[0084] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0085] Perform a leak detection from air to fuel:

[0086] S210, Control the gas supply component to supply gas to the first leak tester 1.

[0087] S220. The first and second ends of one of the two test branches 3 corresponding to the air flow path 110 in the output terminal of the first leak tester 1 are connected. That is, the input and output ends of the first two-position three-way control valve 31 corresponding to the air flow path 110 in the two test branches 3 in the output terminal of the first leak tester 1 are connected, so that the output terminal of the first leak tester 1 is connected to the air flow path 110.

[0088] S230, control the first leakage tester 1 to supply air to one of the two test branches 3 located at the output end of the first leakage tester 1, corresponding to the air flow path 110, and stop the air supply and maintain pressure after a first set time.

[0089] In this embodiment, the first set duration is preferably 3 seconds. It can be understood that after 3 seconds of inflation, the air pressure value of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1, as well as the air pressure value of the air flow path 110, both reach a certain air pressure value.

[0090] S240, after the second set time, the third and fourth ends of the control connection branch 4 are connected, the second leakage tester 2 is controlled to test for cross-leakage, and the second cross-leakage value is recorded. That is, the input and output ends of the second two-position three-way control valve 41 are connected, so that the fuel flow path 120 and the second leakage tester 2 are connected.

[0091] In this embodiment, the second set duration is preferably 15 seconds.

[0092] S250. Determine whether the second leakage value is greater than or equal to the set leakage value. If the second leakage value is greater than or equal to the set leakage value, it is initially determined that there is leakage from air to ignition. If the second leakage value is less than the set leakage value, it is initially determined that there is no leakage from air to ignition.

[0093] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the fuel flow path 120 and the air flow path 110 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0094] Perform air-to-liquid cross-leakage detection:

[0095] S310, Control the gas supply assembly to supply gas to the first leak tester 1.

[0096] S320. The control is set to connect the first end and the second end of one of the two test branches 3 corresponding to the air flow path 110 in the two test branches 3 at the output end of the first leak tester 1. That is, the input end and the output end of the first two-position three-way control valve 31 corresponding to the air flow path 110 in the two test branches 3 at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to the air flow path 110.

[0097] S330, control the first leakage tester 1 to supply air to one of the two test branches 3 located at the output end of the first leakage tester 1, corresponding to the air flow path 110, and stop the air supply and maintain pressure after a first set time.

[0098] In this embodiment, the first set duration is preferably 3 seconds. It can be understood that after 3 seconds of inflation, the air pressure value of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1, as well as the air pressure value of the air flow path 110, both reach a certain air pressure value.

[0099] S340. After the second set time, the first and second ends of the test branch 3 set at the output end of the second leak tester 2 are connected, and the second leak tester 2 is controlled to test for cross-leakage and record the third cross-leakage value. Specifically, by controlling the input and output ends of the first two-position three-way control valve 31 set on the test branch 3 at the output end of the second leak tester 2 to connect, the output end of the second leak tester 2 is connected to the coolant flow path 130.

[0100] S350. Determine whether the third leakage value is greater than or equal to the set leakage value. If the third leakage value is greater than or equal to the set leakage value, it is preliminarily determined that there is leakage from air to liquid. If the third leakage value is less than the set leakage value, it is preliminarily determined that there is no leakage from air to liquid.

[0101] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the air flow path 110 and the coolant flow path 130 are both connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0102] Perform a cross-leakage test on the fuel to liquid:

[0103] S410, Control the gas supply assembly to supply gas to the first leak tester 1.

[0104] S420, the first and second ends of one of the two test branches 3 corresponding to the fuel flow path 120 in the output terminal of the first leak tester 1 are connected. That is, the input and output ends of one of the first two-position three-way control valves 31 corresponding to the fuel flow path 120 in the two test branches 3 in the output terminal of the first leak tester 1 are connected, so that the output terminal of the first leak tester 1 is connected to the fuel flow path 120.

[0105] S430, control the first leak tester 1 to supply gas to one of the two test branches 3 located at the output end of the first leak tester 1, corresponding to the fuel flow path 120, and stop the gas supply and maintain pressure after a first set time.

[0106] In this embodiment, the preferred first setting time is 3 seconds. It can be understood that after 3 seconds of inflation, the air pressure value of one of the two test branches 3 corresponding to the fuel flow path 120 at the output end of the first leak tester 1, as well as the air pressure value of the fuel flow path 120, both reach a certain air pressure value.

[0107] S440. After the second set time, the first and second ends of the test branch 3 set at the output end of the second leak tester 2 are connected, and the second leak tester 2 is controlled to test for cross-leakage and record the fourth cross-leakage value. Among them, the input and output ends of the first two-position three-way control valve 31 set on the test branch 3 at the output end of the second leak tester 2 are connected, so that the coolant flow path 130 and the second leak tester 2 are connected.

[0108] In this embodiment, the second set duration is preferably 15 seconds.

[0109] S450. Determine whether the fourth leakage value is greater than or equal to the set leakage value. If the fourth leakage value is greater than or equal to the set leakage value, it is preliminarily determined that there is a leakage in the fuel. If the fourth leakage value is less than the set leakage value, it is preliminarily determined that there is no leakage in the fuel.

[0110] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the fuel flow path 120 and the coolant flow path 130 are both connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0111] Simultaneously perform external leakage detection in the coolant flow path, as well as one of external leakage detection in the fuel flow path and external leakage detection in the air flow path. In this embodiment, simultaneous external leakage detection in the coolant flow path and external leakage detection in the fuel flow path is taken as an example.

[0112] S510 controls the gas supply assembly to supply gas to both the first leak tester 1 and the second leak tester 2.

[0113] S520: The first and second ends of the two test branches 3 located at the output end of the first leak tester 1 are connected, and the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are also connected. That is, the input and output ends of the first two-position three-way control valve 31 on the two test branches 3 located at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to both the air flow path 110 and the fuel flow path 120; the input and output ends of the first two-position three-way control valve 31 on the test branch 3 located at the output end of the second leak tester 2 are connected, so that the output end of the second leak tester 2 is connected to the coolant flow path 130.

[0114] S530, control the first leak tester 1 to supply air and maintain pressure to the two test branches 3 set at the output end of the first leak tester 1, and at the same time, control the second leak tester 2 to supply air and maintain pressure to the test branch 3 set at the output end of the second leak tester 2.

[0115] S540. After the second set time, the second end of one of the two test branches 3 corresponding to the air flow path 110 in the output terminal of the first leak tester 1 is connected to the outside. The first leak tester 1 is controlled to test whether the fuel flow path 120 is leaking externally and record the first external leakage value. At the same time, the second leak tester 2 is controlled to test whether the coolant flow path 130 is leaking externally and record the second external leakage value.

[0116] S550, Determine whether the first external leakage value is greater than or equal to the set external leakage value; determine whether the second external leakage value is greater than or equal to the set external leakage value.

[0117] If the first external leakage value is greater than or equal to the set external leakage value, it is preliminarily determined that there is an external leakage in the fuel flow path 120. If the first external leakage value is less than the set external leakage value, it is preliminarily determined that there is no external leakage in the fuel flow path 120.

[0118] If the second external leakage value is greater than or equal to the set external leakage value, it is preliminarily determined that there is an external leakage in the coolant flow path 130. If the second external leakage value is less than the set external leakage value, it is preliminarily determined that there is no external leakage in the coolant flow path 130.

[0119] The external leakage value was set as an empirical value obtained from a large number of previous experiments.

[0120] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0121] Perform airflow path external leakage detection:

[0122] S610 controls the gas supply assembly to supply gas to both the first leak tester 1 and the second leak tester 2.

[0123] S620: The first and second ends of the two test branches 3 located at the output end of the first leak tester 1 are connected, and the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are also connected. That is, the input and output ends of the first two-position three-way control valve 31 on the two test branches 3 located at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to both the air flow path 110 and the fuel flow path 120; the input and output ends of the first two-position three-way control valve 31 on the test branch 3 located at the output end of the second leak tester 2 are connected, so that the output end of the second leak tester 2 is connected to the coolant flow path 130.

[0124] S630, control the first leak tester 1 to supply air and maintain pressure to the two test branches 3 set at the output end of the first leak tester 1, and at the same time, control the second leak tester 2 to supply air and maintain pressure to the test branch 3 set at the output end of the second leak tester 2.

[0125] S640. After the second set time, the second end of one of the two test branches 3 corresponding to the fuel flow path 120 at the output end of the first leak tester 1 is connected to the outside. The first leak tester 1 is then controlled to test whether the fuel flow path 120 is leaking externally and records the third external leakage value. It can be understood that the first end and the second end of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leak tester 1 are kept connected. That is, the input end and the output end of the first two-position three-way control valve 31 on the test branch 3 are kept connected, so that the gas in the air flow path 110 can flow to the first leak tester 1 through the test branch 3 after being pressurized.

[0126] Specifically, during this process, the input and output terminals of the first two-position three-way control valve 31 corresponding to the second leak tester 2 can be kept connected; or, the output terminal of the first two-position three-way control valve 31 corresponding to the second leak tester 2 can be connected to the outside.

[0127] S650. Determine whether the third external leakage value is greater than or equal to the set external leakage value. If the third external leakage value is greater than or equal to the set external leakage value, it is preliminarily determined that there is an external leakage in the air flow path 110. If the third external leakage value is less than the set external leakage value, it is preliminarily determined that there is no external leakage in the air flow path 110.

[0128] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0129] It is understandable that the method for simultaneously detecting external leaks in the coolant flow path and the air flow path is similar to the method for simultaneously detecting external leaks in the coolant flow path and the fuel flow path, and will not be elaborated here. Specifically, after obtaining the series leakage detection results and external leakage detection results of the fuel cell stack 100, in order to ensure the accuracy of the detection results, the fuel cell stack airtightness detection method also includes:

[0130] Perform a cross-leakage check from air to fuel:

[0131] S710, Control the gas supply assembly to supply gas to the first leak tester 1.

[0132] S720, the first and second ends of the two test branches 3 located at the output end of the first leak tester 1 are connected. That is, the input and output ends of the first two-position three-way control valve 31 located on the two test branches 3 at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to both the air flow path 110 and the fuel flow path 120.

[0133] S730: Control the first leak tester 1 to supply air to the two test branches 3 set at the output end of the first leak tester 1, and stop the air supply and maintain pressure after a first set time.

[0134] In this embodiment, the first set time is preferably 3 seconds. After 3 seconds of inflation, the air pressure values ​​of the two test branches 3, the air flow path 110 and the fuel flow path 120 set at the output end of the first leak tester 1 all reach a certain air pressure value.

[0135] S740, after the second set time, the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are connected; the input and output ends of the fourth two-position three-way control valve 61 located at the output end of the second leak tester 2 are connected. This connects the coolant flow path 130 to the second leak tester 2, and also connects the coolant flow path 130 to the input end of the fourth two-position three-way control valve 61 located at the output end of the second leak tester 2, allowing a portion of the gas flowing to the input end of the fourth two-position three-way control valve 61 to be discharged to the outside.

[0136] Specifically, the amount of gas leaked from the first leak hole can be calculated based on the detection time and the flow rate of the first leak hole.

[0137] S750 controls the second leakage tester 2 to test and record the first series of leakage verification values.

[0138] S760. Determine whether the first string of missing values ​​is accurate based on the first string of missing check values.

[0139] Specifically, the steps for determining whether the first string of missing values ​​is accurate based on the first string of missing check values ​​include:

[0140] Calculate whether the deviation rate is within the set deviation rate range; where, deviation rate = (|first string leakage value - (first string leakage check value - amount of gas leaked from the first leakage hole)|) / first string leakage value.

[0141] If the deviation rate is within the set deviation rate range, it indicates that the first series of missing values ​​is accurate.

[0142] If the deviation rate is not within the set deviation rate range, it indicates that the first string of missing values ​​is inaccurate.

[0143] Specifically, in this embodiment, the set deviation rate is 10% within the set deviation rate range. When the deviation rate is less than 10%, it indicates that the first string of missing values ​​is accurate. When the deviation rate is greater than or equal to 10%, it indicates that the first string of missing values ​​is inaccurate.

[0144] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0145] This ensures the accuracy of the first string of leak values ​​obtained from the verification and detection, thereby further ensuring the reliability of the fuel cell stack 100 in its later use.

[0146] Perform a leak check from empty to ignition:

[0147] S810, control the gas supply assembly to supply gas to the first leak tester 1.

[0148] S820, the first and second ends of one of the two test branches 3 corresponding to the air flow path 110 in the output terminal of the first leak tester 1 are connected. That is, the input and output ends of the first two-position three-way control valve 31 corresponding to the air flow path 110 in the two test branches 3 in the output terminal of the first leak tester 1 are connected, so that the output terminal of the first leak tester 1 is connected to the air flow path 110.

[0149] S830: Control the first leak tester 1 to supply air to one of the two test branches 3 located at the output end of the first leak tester 1, corresponding to the air flow path 110, and stop the air supply and maintain pressure after a first set time.

[0150] In this embodiment, the first set duration is preferably 3 seconds. After 3 seconds of inflation, the air pressure value of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1, as well as the air pressure value of the air flow path 110, both reach a certain air pressure value.

[0151] S840, after the second set time, connects the third and fourth ends of the control connection branch 4, and connects the input and output ends of another fifth two-position three-way control valve 72. This connects the fuel flow path 120 with the second leak tester 2 and the second leak hole.

[0152] The amount of gas leaking from the second leak hole can be calculated based on the detection time and the flow rate of the second leak hole.

[0153] S850 controls the second leakage tester 2 to test and record the second leakage verification value.

[0154] S860. Determine whether the second string of missing values ​​is accurate based on the second string of missing values.

[0155] Specifically, the steps for determining whether the second string of missing values ​​is accurate based on the second string of missing check values ​​include:

[0156] Calculate whether the deviation rate is within the set deviation rate range; where, deviation rate = (|second string leakage value - (second string leakage check value - amount of gas leaked from the second leakage hole)|) / second string leakage value.

[0157] If the deviation rate is within the set deviation rate range, it indicates that the second string of missing values ​​is accurate.

[0158] If the deviation rate is not within the set deviation rate range, it indicates that the second string of missing values ​​is inaccurate.

[0159] Specifically, in this embodiment, the set deviation rate is 10% within the set deviation rate range. When the deviation rate is less than 10%, it indicates that the second string of missing values ​​is accurate. When the deviation rate is greater than or equal to 10%, it indicates that the second string of missing values ​​is inaccurate.

[0160] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the fuel flow path 120 and the air flow path 110 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0161] This ensures the accuracy of the second string of leak values ​​obtained from the verification and detection, thereby further ensuring the reliability of the fuel cell stack 100 in its later use.

[0162] Perform an air-to-liquid cross-leakage check:

[0163] S910, Control the gas supply assembly to supply gas to the first leak tester 1.

[0164] S920, the first and second ends of one of the two test branches 3 corresponding to the air flow path 110 in the output terminal of the first leak tester 1 are connected. That is, the input and output ends of the first two-position three-way control valve 31 corresponding to the air flow path 110 in the two test branches 3 in the output terminal of the first leak tester 1 are connected, so that the output terminal of the first leak tester 1 is connected to the air flow path 110.

[0165] S930, control the first leakage tester 1 to supply air to one of the two test branches 3 located at the output end of the first leakage tester 1, corresponding to the air flow path 110, and stop the air supply and maintain pressure after a first set time.

[0166] In this embodiment, the first set duration is preferably 3 seconds. After 3 seconds of inflation, the air pressure value of one of the two test branches 3 corresponding to the air flow path 110 at the output end of the first leakage tester 1, as well as the air pressure value of the air flow path 110, both reach a certain air pressure value.

[0167] S940, after the second set time, the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are connected, and the input and output ends of the fourth two-position three-way control valve 61 located at the output end of the second leak tester 2 are connected. This connects the coolant flow path 130 with the second leak tester 2 and the first leak hole on the first verification branch 6 located at the output end of the second leak tester 2.

[0168] S950 controls the second leakage tester 2 to test and records the third leakage verification value.

[0169] S960. Determine whether the third string of missing values ​​is accurate based on the third string of missing values.

[0170] Specifically, the steps for determining whether the third string of missing values ​​is accurate based on the third string of missing check values ​​include:

[0171] Calculate whether the deviation rate is within the set deviation rate range; where, deviation rate = (|third series leak value - (third series leak verification value - amount of gas leaked from the first leak hole)|) / third series leak value. It can be understood that the first leak hole is the first leak hole set on the first verification branch 6 at the output end of the second leak tester 2.

[0172] If the deviation rate is within the set deviation rate range, it indicates that the third string of missing values ​​is accurate.

[0173] If the deviation rate is not within the set deviation rate range, it indicates that the third string of missing values ​​is inaccurate.

[0174] Specifically, in this embodiment, the set deviation rate is 10% within the set deviation rate range. When the deviation rate is less than 10%, it indicates that the third string of missing values ​​is accurate. When the deviation rate is greater than or equal to 10%, it indicates that the third string of missing values ​​is inaccurate.

[0175] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the air flow path 110 and the coolant flow path 130 are both connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0176] This ensures the accuracy of the third string of leak values ​​obtained from the verification and detection, thereby further ensuring the reliability of the fuel cell stack 100 in its later use.

[0177] Perform a cross-leakage check on the fuel to liquid:

[0178] S1010, Control the gas supply component to supply gas to the first leak tester 1.

[0179] S1020, the first and second ends of one of the two test branches 3 corresponding to the fuel flow path 120 in the output terminal of the first leak tester 1 are connected. That is, the input and output ends of one of the first two-position three-way control valves 31 corresponding to the fuel flow path 120 in the two test branches 3 in the output terminal of the first leak tester 1 are connected, so that the output terminal of the first leak tester 1 is connected to the fuel flow path 120.

[0180] S1030, control the first leak tester 1 to supply gas to one of the two test branches 3 located at the output end of the first leak tester 1, corresponding to the fuel flow path 120, and stop the gas supply and maintain pressure after a first set time.

[0181] In this embodiment, the first set duration is preferably 3 seconds. After 3 seconds of inflation, the pressure values ​​of the two test branches 3 at the output end of the first leak tester 1, corresponding to one of the fuel flow paths 120, and the pressure value of the fuel flow path 120, both reach a certain pressure value.

[0182] S1040, after the second set time, the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are connected, and the input and output ends of the fourth two-position three-way control valve 61 located at the output end of the second leak tester 2 are connected. This connects the coolant flow path 130 with the second leak tester 2 and the first leak hole on the first verification branch 6 located at the output end of the second leak tester 2.

[0183] S1050 controls the second leakage tester 2 to test and record the fourth leakage verification value.

[0184] S1060. Determine whether the fourth string of missing values ​​is accurate based on the fourth string of missing values.

[0185] Specifically, the steps for determining whether the fourth string of missing values ​​is accurate based on the fourth string's check value include:

[0186] Calculate whether the deviation rate is within the set deviation rate range; where, deviation rate = (|fourth series leak value - (fourth series leak verification value - amount of gas leaked from the first leak hole)|) / fourth series leak value. It can be understood that the first leak hole is the first leak hole set on the first verification branch 6 at the output end of the second leak tester 2.

[0187] If the deviation rate is within the set deviation rate range, it indicates that the fourth string of missing values ​​is accurate.

[0188] If the deviation rate is not within the set deviation rate range, it indicates that the fourth string of missing values ​​is inaccurate.

[0189] Specifically, in this embodiment, the set deviation rate is 10% within the set deviation rate range. When the deviation rate is less than 10%, it indicates that the fourth string of missing values ​​is accurate. When the deviation rate is greater than or equal to 10%, it indicates that the fourth string of missing values ​​is inaccurate.

[0190] This ensures the accuracy of the fourth string of leak values ​​obtained from the verification test, thereby further ensuring the reliability of the fuel cell stack 100 in its later use.

[0191] Specifically, after the test by the second leak tester 2 is completed, the input and output terminals of the two third two-position three-way control valves 5 corresponding to the fuel flow path 120 and the coolant flow path 130 are both connected. This allows the gas in the fuel cell stack airtightness testing system and the gas in the stack 100 to be discharged to the outside, facilitating subsequent use.

[0192] Simultaneously perform external leakage checks on the coolant flow path, as well as one of the external leakage checks on the fuel flow path and the external leakage checks on the air flow path. In this embodiment, simultaneous external leakage checks on the coolant flow path and the fuel flow path are taken as an example.

[0193] S1110, controls the gas supply assembly to supply gas to both the first leak tester 1 and the second leak tester 2.

[0194] S1120: The first and second ends of the two test branches 3 located at the output end of the first leak tester 1 are connected, and the first and second ends of the test branch 3 located at the output end of the second leak tester 2 are also connected. That is, the input and output ends of the first two-position three-way control valve 31 on the two test branches 3 located at the output end of the first leak tester 1 are connected, so that the output end of the first leak tester 1 is connected to both the air flow path 110 and the fuel flow path 120; the input and output ends of the first two-position three-way control valve 31 on the test branch 3 located at the output end of the second leak tester 2 are connected, so that the output end of the second leak tester 2 is connected to the coolant flow path 130.

[0195] S1130: Control the first leak tester 1 to supply air and maintain pressure to the two test branches 3 set at the output end of the first leak tester 1; at the same time, control the second leak tester 2 to supply air and maintain pressure to the test branch 3 set at the output end of the second leak tester 2.

[0196] S1140, after the second set time, the input and output terminals of the two fourth two-position three-way control valves 61 are connected, and the second end of one of the two test branches 3 corresponding to the air flow path 110 at the output terminal of the first leak tester 1 is connected to the outside. This connects the fuel flow path 120 with the first leak tester 1 and the first leak hole of the first verification branch 6 at the output terminal of the first leak tester 1. It also connects the coolant flow path 130 with the second leak tester 2 and the first leak hole of the first verification branch 6 at the output terminal of the second leak tester 2.

[0197] S1150: Control the first leakage tester 1 to test and record the first external leakage verification value. At the same time, control the second leakage tester 2 to test and record the second external leakage verification value.

[0198] S1160. Determine whether the first external leakage value is accurate based on the first external leakage check value; determine whether the second external leakage value is accurate based on the second external leakage check value.

[0199] Specifically, the specific steps for determining whether the first external leakage value is accurate based on the first external leakage check value, and the specific steps for determining whether the second external leakage value is accurate based on the second external leakage check value, are similar to the method for determining the accuracy of the first string of leakage values ​​described above, so they will not be repeated here.

[0200] Specifically, after the tests by the first leak tester 1 and the second leak tester 2 are completed, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0201] Perform an external leakage check on the airflow path:

[0202] S1210, control the gas supply assembly to supply gas to both the first leak tester 1 and the second leak tester 2.

[0203] S1220, The first and second ends of the two test branches 3 set at the output end of the first leakage tester 1 are connected, and the first and second ends of the test branch 3 set at the output end of the second leakage tester 2 are connected.

[0204] S1230: Control the first leak tester 1 to supply air and maintain pressure to the two test branches 3 set at the output end of the first leak tester 1; at the same time, control the second leak tester 2 to supply air and maintain pressure to the test branch 3 set at the output end of the second leak tester 2.

[0205] S1240, after the second set time, the second end of one of the two test branches 3 corresponding to the fuel flow path 120 in the output end of the first leak tester 1 is connected to the outside, and the input end and output end of the fourth two-position three-way control valve 61 in the output end of the first leak tester 1 are connected.

[0206] S1250 controls the first leakage tester 1 to test and records the third external leakage verification value.

[0207] S1260. Determine whether the third external leakage value is accurate based on the third external leakage check value.

[0208] Specifically, the steps for determining whether the third external leakage value is accurate based on the third external leakage check value are similar to the method for determining the accuracy of the first string of leakage values, so they will not be repeated here.

[0209] Specifically, after the first leak tester 1 completes the test, the input and output terminals of the three third two-position three-way control valves 5 are connected. This allows the gas in the fuel cell stack airtightness testing system and the gas inside the stack 100 to be discharged to the outside, facilitating subsequent use.

[0210] Therefore, it is possible to detect the airtightness of the fuel cell stack 100, improve the efficiency of detecting the airtightness of the fuel cell stack 100, verify the accuracy of the airtightness test results of the fuel cell stack 100, and improve the efficiency of verifying the accuracy of the airtightness test results of the fuel cell stack 100.

[0211] Specifically, when performing air tightness testing on fuel cell stack 100, the following must be performed: air-fuel to liquid leakage test, air-fuel leakage test, coolant flow path external leakage test, fuel flow path external leakage test, and air flow path external leakage test. It is understood that air-fuel leakage test and fuel-fuel leakage test can be performed, either one or both, depending on the actual operating conditions.

[0212] When performing air tightness testing on fuel cell stack 100, taking air-to-liquid leakage testing and fuel-to-liquid leakage testing as examples, the execution order of air-fuel-to-liquid leakage testing, air-to-fuel leakage testing, coolant flow path external leakage testing, fuel flow path external leakage testing, air flow path external leakage testing, air-to-liquid leakage testing, and fuel-to-liquid leakage testing can be adaptively adjusted according to actual operating conditions.

[0213] More specifically, the type of verification for fuel cell stack 100 is determined based on the type of test performed on the fuel cell stack 100. For example, if an air-fuel to liquid leakage test is performed on the fuel cell stack 100, then an air-fuel to liquid leakage verification test is also performed on the fuel cell stack 100.

[0214] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for detecting the airtightness of a fuel cell stack, used to detect the airtightness of a stack (100), wherein the stack (100) is provided with an air flow path (110), a fuel flow path (120), and a coolant flow path (130), characterized in that, The fuel cell stack airtightness testing system includes a gas supply component, a first leak tester (1), a second leak tester (2), and three test branches (3). The first leak tester (1) and the second leak tester (2) are connected in parallel and are both connected to the output end of the gas supply component, which is used for gas supply. The output end of the first leak tester (1) is provided with two test branches (3). The two test branches (3) are connected in parallel, and the first end of each of the two test branches (3) is connected to the output end of the first leak tester (1). The second end of each of the two test branches (3) is connected to the input end of the air flow path (110) and the input end of the fuel flow path (120), respectively. The output end of the second leak tester (2) is provided with one test branch (3). The first end of the test branch (3) is connected to the output end of the second leak tester (2), and the second end of the test branch (3) is connected to the input end of the coolant flow path (130). The test branch (3) is configured to selectively connect the first end and the second end, or connect the second end to the outside; the output ends of the air flow path (110), the fuel flow path (120) and the coolant flow path (130) are all blocked; the first leakage tester (1), the second leakage tester (2) and the three test branches of the fuel cell stack airtightness detection system are controlled to work (3) by the fuel cell stack airtightness detection method, so that the first leakage tester (1), the second leakage tester (2) and the three test branches (3) can cooperate to form an air-fuel to liquid leakage detection flow path, an air-to-liquid leakage detection flow path, a fuel-to-liquid leakage detection flow path, and an external leakage detection flow path; and the gas supply component is controlled by the fuel cell stack airtightness detection method to supply gas to the air-fuel to liquid leakage detection flow path, the air-to-liquid leakage detection flow path, the fuel-to-liquid leakage detection flow path, and the external leakage detection flow path; The method for detecting the airtightness of the fuel cell stack includes: Perform air-fuel to liquid leakage detection: control the gas supply assembly to supply gas to the first leakage tester (1); The first and second ends of the two test branches (3) set at the output end of the first leak tester (1) are connected; the first leak tester (1) is controlled to supply air to the two test branches (3) set at the output end of the first leak tester (1), and the air supply is stopped and pressure is maintained after a first set time; after a second set time, the first and second ends of the test branch (3) set at the output end of the second leak tester (2) are connected, and the second leak tester (2) is controlled to test whether there is a series leak and record the first series leak value.

2. The fuel cell stack airtightness testing method according to claim 1, characterized in that, The fuel cell stack airtightness testing method further includes: Perform air-to-liquid cross-leakage detection: control the air supply assembly to supply air to the first leak tester (1); control the connection between the first end and the second end of one of the two test branches (3) corresponding to the air flow path (110) at the output end of the first leak tester (1); control the first leak tester (1) to supply air to one of the two test branches (3) corresponding to the air flow path (110) at the output end of the first leak tester (1), stop the air supply and maintain pressure after the first set time; after the second set time, control the connection between the first end and the second end of the test branch (3) at the output end of the second leak tester (2), control the second leak tester (2) to test whether there is cross-leakage, and record the third cross-leakage value; And / or, perform a fuel-to-liquid cross-leakage detection: control the gas supply assembly to supply gas to the first leak tester (1); control the connection of the first end and the second end of one of the two test branches (3) located at the output end of the first leak tester (1) corresponding to the fuel flow path (120); control the first leak tester (1) to supply gas to one of the two test branches (3) located at the output end of the first leak tester (1) corresponding to the fuel flow path (120), stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the first end and the second end of the test branch (3) located at the output end of the second leak tester (2), control the second leak tester (2) to test whether there is a cross-leakage, and record the fourth cross-leakage value.

3. The fuel cell stack airtightness testing method according to claim 1, characterized in that, The fuel cell stack airtightness testing method further includes: Simultaneously perform external leakage detection of coolant flow path, and one of external leakage detection of fuel flow path and external leakage detection of air flow path: control the air supply assembly to supply air to both the first leakage tester (1) and the second leakage tester (2); control the connection between the first end and the second end of the two test branches (3) set at the output end of the first leakage tester (1), and control the connection between the first end and the second end of the test branch (3) set at the output end of the second leakage tester (2); control the first leakage tester (1) to supply air to both the first and second ends of the test branches (3) set at the output end of the first leakage tester (1). The test branch (3) is supplied with air and pressurized. At the same time, the second leak tester (2) is controlled to supply air and pressurize the test branch (3) set at the output end of the second leak tester (2). After a second set time, the second end of one of the two test branches (3) set at the output end of the first leak tester (1) is connected to the outside. The first leak tester (1) is controlled to test whether there is an external leak and record the first external leak value. At the same time, the second leak tester (2) is controlled to test whether the coolant flow path (130) is leaking and record the second external leak value.

4. The fuel cell stack airtightness testing method according to claim 1, characterized in that, The fuel cell stack airtightness testing system further includes a connecting branch (4), the third end of which is connected to the output end of the second leak tester (2), and the fourth end of which is connected to the second end of one of the two test branches (3) located at the output end of the first leak tester (1). The connecting branch (4) is configured to selectively connect the third end and the fourth end, or connect the fourth end to the outside.

5. The fuel cell stack airtightness testing method according to claim 4, characterized in that, When the fourth end of the connecting branch (4) is connected to the second end of one of the two test branches (3) located at the output end of the first leakage tester (1) corresponding to the fuel flow path (120), the fuel cell stack airtightness detection method further includes: Perform air-to-fuel leakage detection: control the gas supply assembly to supply gas to the first leakage tester (1); control the connection of the first end and the second end of the two test branches (3) set at the output end of the first leakage tester (1) corresponding to the air flow path (110); control the first leakage tester (1) to supply gas to the one of the two test branches (3) set at the output end of the first leakage tester (1) corresponding to the air flow path (110), stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the third end and the fourth end of the connecting branch (4), control the second leakage tester (2) to test whether there is leakage, and record the second leakage value.

6. The method for detecting the airtightness of a fuel cell stack according to any one of claims 1-5, characterized in that, Both the output end of the first leakage tester (1) and the output end of the second leakage tester (2) are provided with a first verification branch (6), and the first verification branch (6) is distributed in parallel with the test branch (3); the first verification branch (6) includes a fourth two-position three-way control valve (61) and a first leakage pipe (62). The input end of the fourth two-position three-way control valve (61) is used to connect with the output end of the first leakage tester (1) or the output end of the second leakage tester (2). The output end of the fourth two-position three-way control valve (61) is connected to one end of the first leakage pipe (62). The other end of the first leakage pipe (62) is blocked, and the connecting end of the fourth two-position three-way control valve (61) is blocked.

7. The fuel cell stack airtightness testing method according to claim 6, characterized in that, The fuel cell stack airtightness testing method further includes: Perform air-fuel to liquid leakage verification: control the gas supply assembly to supply gas to the first leakage tester (1); control the connection between the first and second ends of the two test branches (3) set at the output end of the first leakage tester (1); control the first leakage tester (1) to supply gas to the two test branches (3) set at the output end of the first leakage tester (1), stop the gas supply and maintain pressure after a first set time; after a second set time, control the connection between the first and second ends of the test branch (3) set at the output end of the second leakage tester (2), control the connection between the input and output ends of the fourth two-position three-way control valve (61) set at the output end of the second leakage tester (2); control the second leakage tester (2) to test and record the first leakage verification value; determine whether the first leakage value is accurate based on the first leakage verification value.

8. The fuel cell stack airtightness testing method according to claim 6, characterized in that, The fuel cell stack airtightness testing method further includes: Perform air-to-liquid leakage verification: Control the air supply assembly to supply air to the first leakage tester (1); control the connection between the first end and the second end of one of the two test branches (3) corresponding to the air flow path (110) at the output end of the first leakage tester (1); control the first leakage tester (1) to supply air to one of the two test branches (3) corresponding to the air flow path (110) at the output end of the first leakage tester (1), stop the air supply and maintain pressure after the first set time; after the second set time, control the connection between the first end and the second end of the test branch (3) at the output end of the second leakage tester (2), control the connection between the input end and the output end of the fourth two-position three-way control valve (61) at the output end of the second leakage tester (2); control the second leakage tester (2) to test and record the third leakage verification value; determine whether the third leakage value is accurate based on the third leakage verification value; And / or, perform a fuel-to-liquid leakage check: control the gas supply assembly to supply gas to the first leakage tester (1); control the connection of the first end and the second end of one of the two test branches (3) at the output end of the first leakage tester (1) corresponding to the fuel flow path (120); control the first leakage tester (1) to supply gas to one of the two test branches (3) at the output end of the first leakage tester (1) corresponding to the fuel flow path (120), stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the first end and the second end of the test branch (3) at the output end of the second leakage tester (2), control the connection of the input end and the output end of the fourth two-position three-way control valve (61) at the output end of the second leakage tester (2); control the second leakage tester (2) to test and record the fourth leakage check value; determine whether the fourth leakage value is accurate based on the fourth leakage check value.

9. The fuel cell stack airtightness testing method according to claim 6, characterized in that, The fuel cell stack airtightness testing method further includes: Simultaneously perform external leakage checks on the coolant flow path, fuel flow path, and air flow path: control the air supply assembly to supply air to both the first leak tester (1) and the second leak tester (2); control the connection between the first and second ends of the two test branches (3) located at the output end of the first leak tester (1); control the connection between the first and second ends of the test branch (3) located at the output end of the second leak tester (2); control the first leak tester (1) to supply air to the two test branches (3) located at the output end of the first leak tester (1) and maintain pressure, while simultaneously controlling the second leak tester (2). Gas is supplied to the test branch (3) located at the output end of the second leak tester (2) and pressure is maintained; after a second set time, the input and output ends of the two fourth two-position three-way control valves (61) are connected, and the second end of one of the two test branches (3) located at the output end of the first leak tester (1) is connected to the outside; the first leak tester (1) is controlled to test and record the first external leakage verification value, and at the same time, the second leak tester (2) is controlled to test and record the second external leakage verification value; the accuracy of the first external leakage value is determined based on the first external leakage verification value, and the accuracy of the second external leakage value is determined based on the second external leakage verification value.

10. The fuel cell stack airtightness testing method according to claim 7, characterized in that, The specific steps for determining whether the first string leakage value is accurate based on the first string leakage check value include: Calculate whether the deviation rate is within the set deviation rate range; wherein, the deviation rate = (|first string leakage value - (first string leakage verification value - amount of gas leaked from the first leakage pipe)|) / first string leakage value; If the deviation rate is within the set deviation rate range, it indicates that the first string of missing values ​​is accurate; If the deviation rate is not within the set deviation rate range, it indicates that the first string of missing values ​​is inaccurate.

11. The fuel cell stack airtightness testing method according to claim 5, characterized in that, The output end of the first leakage tester (1) is also provided with a second verification branch (7). The fifth end of the second verification branch (7) is connected to the output end of the first leakage tester (1), and the sixth end of the second verification branch (7) is connected to the connecting branch (4). The second verification branch (7) is provided with a second leakage pipe (71) and two fifth two-position three-way control valves (72). The two ends of the second leakage pipe (71) are respectively connected to the output ends of the two fifth two-position three-way control valves (72). The input end of one of the fifth two-position three-way control valves (72) is connected to the fifth end of the second verification branch (7), and the connecting end of one of the fifth two-position three-way control valves (72) is blocked. The input end of the other fifth two-position three-way control valve (72) is connected to the sixth end of the second verification branch (7), and the connecting end of the other fifth two-position three-way control valve (72) is blocked.

12. The fuel cell stack airtightness testing method according to claim 11, characterized in that, The fuel cell stack airtightness testing method further includes: Perform air-to-fuel leakage verification: Control the gas supply assembly to supply gas to the first leakage tester (1); control the connection of the first end and the second end of one of the two test branches (3) located at the output end of the first leakage tester (1) corresponding to the air flow path (110); control the first leakage tester (1) to supply gas to one of the two test branches (3) located at the output end of the first leakage tester (1) corresponding to the air flow path (110), stop the gas supply and maintain pressure after the first set time; after the second set time, control the connection of the third end and the fourth end of the connecting branch (4) to connect, and control the connection of the input end and the output end of the other fifth two-position three-way control valve (72); control the second leakage tester (2) to test and record the second leakage verification value; determine whether the second leakage value is accurate based on the second leakage verification value.

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