An automatic testing device for fuel cell stack air tightness

Abstract

The application relates to the technical field of fuel cell testing, in particular to an automatic testing device for the air tightness of a fuel cell stack, which comprises a medium switching control unit, a pressure regulating unit, an air tightness testing unit and a PLC controller, the medium switching control unit is composed of four medium branches and a fifth electromagnetic valve, the four medium branches are connected with the fifth electromagnetic valve, the medium branches comprise a helium-nitrogen mixed gas branch, a helium gas branch, a nitrogen gas branch and a hydrogen gas branch, the pressure regulating unit comprises a pressure regulator and a fifth pressure sensor, and the air tightness testing unit is composed of 12 electromagnetic valves, three pressure sensors and a mass flowmeter. The application can meet all testing requirements, automatically complete testing by generating a testing scheme, and greatly reduces complicated manual operation, so that testing is accurate, fast and stable, and testing errors caused by improper or inaccurate manual operation are avoided.

Description

Technical Field

[0001] This application relates to the field of fuel cell testing technology, and in particular to an automatic testing device for the airtightness of fuel cell stacks. Background Technology

[0002] The hydrogen fuel cell stack (hereinafter referred to as the fuel cell stack) has three fluid transport channels: the anode channel (also known as the hydrogen cavity), the cathode channel (also known as the air cavity), and the coolant channel (also known as the water cavity). The anode channel supplies the hydrogen required for the fuel cell stack reaction, the cathode channel supplies the air (oxygen) required for the fuel cell stack reaction, and the coolant channel (water cavity) supplies the coolant for the fuel cell stack reaction.

[0003] For the safe and normal operation of a fuel cell stack, these three channels need to have good airtightness, meaning good airtightness between each channel and between the channels and the external environment. Internal or external leakage of hydrogen from the fuel cell stack between these three channels will adversely affect its efficient operation and pose serious safety hazards. Therefore, airtightness testing is a necessary step in the development, production, and use of fuel cell stacks.

[0004] However, among the existing fuel cell air tightness testing technologies, there is no technical solution that can automatically perform air tightness testing for different needs. Utility Model Content

[0005] The main objective of this application is to provide an automatic testing device for the airtightness of fuel cell stacks, so as to meet the airtightness testing requirements of existing national standards and product development processes.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] According to a first aspect of the present invention, the present invention claims protection for an automatic testing device for the airtightness of a fuel cell stack, comprising a medium switching control unit, a pressure regulating unit, an airtightness testing unit, and a PLC controller.

[0008] The medium switching control unit consists of four medium branches and a fifth solenoid valve, with all four medium branches connected to the fifth solenoid valve.

[0009] The medium branch includes a helium-nitrogen mixed gas branch, a helium gas branch, a nitrogen gas branch, and a hydrogen gas branch;

[0010] The helium-nitrogen mixed gas branch consists of a first manual ball valve, a first mechanical pressure reducing valve, a first filter, a first solenoid valve, a first pressure sensor, and a first check valve, which are connected in sequence.

[0011] The helium branch consists of a second manual ball valve, a second mechanical pressure reducing valve, a second filter, a second solenoid valve, a second pressure sensor, and a second check valve, which are connected in sequence.

[0012] The nitrogen branch consists of a third manual ball valve, a third mechanical pressure reducing valve, a third filter, a third solenoid valve, a third pressure sensor, and a third check valve, which are connected in sequence.

[0013] The hydrogen branch consists of the fourth manual ball valve, the fourth mechanical pressure reducing valve, the fourth filter, the fourth solenoid valve, the fourth pressure sensor, and the fourth check valve, which are connected in sequence.

[0014] The pressure regulating unit includes a pressure regulator and a fifth pressure sensor;

[0015] The airtightness testing unit consists of 12 solenoid valves, 3 pressure sensors and a mass flow meter;

[0016] The PLC controller is connected to the media switching control unit, the pressure regulation unit, and the airtightness testing unit, respectively.

[0017] Furthermore, the specific connection relationship of the airtightness testing unit is as follows: the output end of the pressure regulating unit is divided into two branches. The first branch is equipped with a sixth solenoid valve, and the second branch is equipped with a thirteenth solenoid valve, a mass flow meter, and a fifteenth solenoid valve. The pipeline between the mass flow meter and the fifteenth solenoid valve is connected to the pipeline after the sixth solenoid valve through the fourteenth solenoid valve. Subsequently, the first branch is divided into three branches leading to the test object. The hydrogen inlet branch is equipped with a seventh solenoid valve and a sixth pressure sensor in sequence, and a hydrogen outlet and an eighth solenoid valve on the other side of the test object. The air inlet branch is equipped with a ninth solenoid valve and a seventh pressure sensor in sequence, and an air outlet and a tenth solenoid valve on the other side of the test object. The coolant inlet branch is equipped with an eleventh solenoid valve and an eighth pressure sensor in sequence, and a coolant outlet and a twelfth solenoid valve on the other side of the test object. After flowing out of the test object, it leads to the second branch, which is connected between the thirteenth solenoid valve and the mass flow meter through the sixteenth solenoid valve, and connected to the right side of the fifteenth solenoid valve through the seventeenth solenoid valve.

[0018] Furthermore, each of the aforementioned manual ball valves is used to manually control the opening and closing of each media branch.

[0019] Furthermore, each of the aforementioned mechanical pressure reducing valves is used to adjust the pressure of each medium branch to 1 MPa for use by the testing device.

[0020] Furthermore, when the test is completed or the pressure is abnormal, the pressure is quickly released through the fifth solenoid valve.

[0021] Furthermore, the voltage regulator adjusts the output pressure using a 4-20mA current signal.

[0022] Furthermore, the pressure regulator uses a combination of feedforward and PID control to adjust the output pressure of the medium branch, thereby improving the accuracy of pressure regulation and control.

[0023] This application relates to the field of fuel cell testing technology, and more particularly to an automatic testing device for the airtightness of fuel cell stacks. The device includes a medium switching control unit, a pressure regulation unit, an airtightness testing unit, and a PLC controller. In practical use, the device selects the required test medium gas source according to testing needs, sets the pressure regulation parameters and test duration, determines and inputs the open / closed status of each solenoid valve during the pressure regulation process, determines and inputs the open / closed status of each solenoid valve after test data recording, generates a test plan based on the relevant automatic test data, and sends the test plan to the PLC controller for automatic execution. This invention can meet the testing requirements for the airtightness of fuel cell stacks, and automatically completes the test by generating a test plan. The test is accurate, fast, and stable, reducing manual operation and avoiding test errors caused by improper or inaccurate manual operation. Attached Figure Description

[0024] Figure 1 A structural diagram of an automated testing device for the airtightness of a fuel cell stack, as claimed in an embodiment of this application;

[0025] Figure 2 A structural diagram of an airtightness testing unit of an automated testing device for the airtightness of a fuel cell stack, as claimed in an embodiment of this application;

[0026] Figure 3 A flowchart of a media switching control device for an automatic testing apparatus for the airtightness of a fuel cell stack, as claimed in an embodiment of this application;

[0027] Figure 4 A schematic diagram of the basic control principle of the pressure regulation unit of an automatic testing device for the airtightness of a fuel cell stack, as claimed in an embodiment of this application;

[0028] Figure 5 A current-pressure calibration curve of an automatic testing device for the airtightness of a fuel cell stack, as claimed in the embodiments of this application;

[0029] Figure 6 A schematic diagram of the pressure regulation structure of an automatic testing device for the airtightness of a fuel cell stack, as claimed in an embodiment of this application;

[0030] Figure 7 This is a flowchart illustrating the workflow of an automated testing method for the airtightness of a fuel cell stack, as claimed in an embodiment of this application. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0032] The terms "first," "second," and "third" in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] Relevant standards have also specified in detail the airtightness testing methods and requirements for fuel cell stacks, fuel cell systems, and related modules. Currently, the main standards related to fuel cell airtightness include: GB / T20042.2-2008 "General Technical Conditions for Proton Exchange Membrane Fuel Cell Stacks", GB / T 33978-2017 "Proton Exchange Membrane Fuel Cell Modules for Road Vehicles", GB / T 29838-2013 "Fuel Cell Modules", GB / T 36288-2018 "Safety Requirements for Fuel Cell Stacks in Fuel Cell Electric Vehicles", GB / T24554-2022 "Performance Test Methods for Fuel Cell Engines", GB / T 25319-2010 "Technical Conditions for Fuel Cell Power Generation Systems for Automobiles", and GB / T 33979-2017 "Low Temperature Characteristic Test Methods for Proton Exchange Membrane Fuel Cell Power Generation Systems". In addition, fuel cell stack manufacturers also have their own specified airtightness testing requirements and methods.

[0035] According to the first embodiment of the present invention, referring to Figure 1 This invention claims protection for an automatic testing device for the airtightness of a fuel cell stack, comprising a medium switching control unit, a pressure regulating unit, an airtightness testing unit, and a PLC controller;

[0036] The medium switching control unit consists of four medium branches and a fifth solenoid valve, with all four medium branches connected to the fifth solenoid valve.

[0037] The medium branch includes a helium-nitrogen mixed gas branch, a helium gas branch, a nitrogen gas branch, and a hydrogen gas branch;

[0038] The helium-nitrogen mixed gas branch consists of a first manual ball valve, a first mechanical pressure reducing valve, a first filter, a first solenoid valve, a first pressure sensor, and a first check valve, which are connected in sequence.

[0039] The helium branch consists of a second manual ball valve, a second mechanical pressure reducing valve, a second filter, a second solenoid valve, a second pressure sensor, and a second check valve, which are connected in sequence.

[0040] The nitrogen branch consists of a third manual ball valve, a third mechanical pressure reducing valve, a third filter, a third solenoid valve, a third pressure sensor, and a third check valve, which are connected in sequence.

[0041] The hydrogen branch consists of the fourth manual ball valve, the fourth mechanical pressure reducing valve, the fourth filter, the fourth solenoid valve, the fourth pressure sensor, and the fourth check valve, which are connected in sequence.

[0042] The pressure regulating unit includes a pressure regulator and a fifth pressure sensor;

[0043] Reference Figure 2The airtightness testing unit consists of 12 solenoid valves, 3 pressure sensors and a mass flow meter. By automatically controlling the opening and closing status of each solenoid valve group, different testing requirements can be automatically met.

[0044] The PLC controller is connected to the media switching control unit, the pressure regulation unit, and the airtightness testing unit, respectively.

[0045] In this embodiment, the testing device has four gas source interfaces. During use, external gas sources such as helium-nitrogen mixtures, helium, nitrogen, and hydrogen are connected to these interfaces. The opening and closing of each gas source are manually controlled via first, second, third, and fourth manual ball valves. First, second, third, and fourth mechanical pressure reducing valves adjust the pressure of each gas source to 1 MPa for use by the testing device. First, second, third, and fourth filters remove impurities from the gas sources to prevent contamination of the testing device and test samples. During testing, first, second, third, and fourth solenoid valves automatically switch between media. First, second, third, and fourth pressure sensors monitor the pressure status of each medium. First, second, third, and fourth one-way valves prevent gas backflow and cross-contamination between different media. Upon completion of the test or in case of abnormal pressure, a fifth solenoid valve rapidly releases the pressure.

[0046] Furthermore, the specific connection relationship of the airtightness testing unit is as follows: the output end of the pressure regulating unit is divided into two branches. The first branch is equipped with a sixth solenoid valve, and the second branch is equipped with a thirteenth solenoid valve, a mass flow meter, and a fifteenth solenoid valve. The pipeline between the mass flow meter and the fifteenth solenoid valve is connected to the pipeline after the sixth solenoid valve through the fourteenth solenoid valve. Subsequently, the first branch is divided into three branches leading to the test object. The hydrogen inlet branch is equipped with a seventh solenoid valve and a sixth pressure sensor in sequence, and a hydrogen outlet and an eighth solenoid valve on the other side of the test object. The air inlet branch is equipped with a ninth solenoid valve and a seventh pressure sensor in sequence, and an air outlet and a tenth solenoid valve on the other side of the test object. The coolant inlet branch is equipped with an eleventh solenoid valve and an eighth pressure sensor in sequence, and a coolant outlet and a twelfth solenoid valve on the other side of the test object. After flowing out of the test object, it leads to the second branch, which is connected between the thirteenth solenoid valve and the mass flow meter through the sixteenth solenoid valve, and connected to the right side of the fifteenth solenoid valve through the seventeenth solenoid valve.

[0047] Furthermore, in this embodiment, the control logic for media switching is as follows: Figure 3 As shown, gi corresponds to the set medium (i=1 corresponds to a helium-nitrogen mixture, i=2 corresponds to helium, i=3 corresponds to nitrogen, and i=4 corresponds to hydrogen).

[0048] The pressure regulating unit mainly consists of a pressure regulator 1 and a fifth pressure sensor 5, and its basic control principle is as follows: Figure 4As shown, pressure regulator 1 adjusts the output pressure using a 4-20mA current signal. To improve the accuracy of pressure regulation and control, the relationship between the current signal X and the output pressure P of pressure regulator 1 is calibrated using the least squares method, resulting in P = f(X). Figure 5 .

[0049] Furthermore, the pressure regulator uses a current signal and a feedforward + PID combination to adjust the output pressure of the gas source, thereby improving the accuracy of pressure regulation and control.

[0050] In this embodiment, a combination of feedforward and PID control is used to regulate and control the pressure, as follows: Figure 6 As shown, during pressure regulation, firstly, based on the set pressure P_set and the relationship P = f(X), a current value X is given to the pressure regulator, and the pressure sensor 5 value P5 is monitored. If P5 ≠ P_set, the PLC controller adjusts the current value X up or down according to the value of P5 until P5 = P_set, thus completing the pressure regulation process.

[0051] Furthermore, the automatic testing method for the aforementioned automatic testing device for the airtightness of fuel cell stacks is as follows:

[0052] (1) Select the test medium gas source required for the automatic test according to the test requirements, and set the pressure regulation parameters and test duration of the automatic test;

[0053] (2) Determine and input the open / closed status of each solenoid valve during the pressure regulation process;

[0054] (3) Determine and input the open / closed status of each solenoid valve during the test;

[0055] (4) Determine and input the test data recording to determine the open / closed status of each solenoid valve.

[0056] A test plan is generated based on the relevant data from the automatic test, and the test plan is sent to the PLC controller for automatic execution.

[0057] Furthermore, refer to Figure 7 The automatic test also includes selecting the required test medium gas source based on the test requirements, setting the pressure regulation parameters and test duration, and further includes:

[0058] Set the test medium, set the pressure regulation value, pressure regulation error and pressure stabilization time, and set the test duration;

[0059] Once the PLC controller confirms that the medium setting is complete, it executes the pressure regulation process and controls the status of the solenoid valve.

[0060] Furthermore, determining and inputting the open / closed status of each solenoid valve in the scheme during the pressure regulation process also includes:

[0061] Select the solenoid valve to be opened and the solenoid valve to be closed.

[0062] The pressure is adjusted, and the pressure adjustment is considered complete when the difference between the set voltage and the voltage value of the fifth pressure sensor is not greater than the first threshold.

[0063] After obtaining the first duration of continuous operation under the condition of pressure regulation, the test process begins, and the state of the solenoid valve is controlled.

[0064] Furthermore, determining and inputting the open / closed status of each solenoid valve during the test and performing an airtightness test also includes:

[0065] Perform an airtightness test, and collect and record the pressure value of the pressure sensor at the test inlet and the flow rate value of the mass flow meter;

[0066] After continuously testing and recording data for a second period of time, the state of the solenoid valves is controlled, and the open / closed state of each solenoid valve is determined and the test data is recorded.

[0067] In this embodiment, the automatic testing, control, and implementation method for the airtightness of the fuel cell stack only requires inputting four parameters:

[0068] Input parameter 1:

[0069] It consists of the following three parts:

[0070] The test media required for the test (helium-nitrogen mixture, helium, nitrogen, hydrogen);

[0071] Pressure regulation parameters include pressure regulation value P (i.e., the medium pressure required during testing), pressure regulation error δ, and pressure stabilization time t1;

[0072] Test parameters, namely the test duration t2.

[0073] Input parameter 2:

[0074] Determine and input the open / closed status of each solenoid valve in the scheme during the pressure regulation process.

[0075] Input parameter 3:

[0076] Determine and input the open / closed status of each solenoid valve in the test procedure.

[0077] Input parameter 4:

[0078] After determining and inputting the test data, record the open / closed status of each solenoid valve.

[0079] Based on the requirements for fuel cell stack airtightness testing, the specific contents of input parameters 1, 2, 3, and 4 are set to form a corresponding test plan, which is then sent to the PLC controller to control the automatic execution of the airtightness test.

[0080] Furthermore, the testing requirements also include: cavity pressure holding test, water cavity pressure holding test, three-cavity pressure holding test, hydrogen cavity leakage into cavity test, hydrogen cavity leakage into water cavity test, and hydrogen cavity leakage test.

[0081] In this embodiment, the hydrogen chamber pressure holding in a single-chamber pressure holding configuration is used as an example for explanation:

[0082] First, before the experiment, connect the corresponding gas source (helium-nitrogen mixture, helium, nitrogen, hydrogen) to the outside and open the corresponding manual ball valve. Then, reduce the pressure to 1 MPa through the mechanical pressure reducing valve of each branch.

[0083] Given input parameter 1:

[0084] Choose one of the following test media (helium-nitrogen mixture, helium, nitrogen, or hydrogen), assuming that the required test medium is nitrogen;

[0085] Given a specific value for the voltage regulation value P;

[0086] Set the voltage regulation error δ, that is, when |Pset-P5|≤δ, it is considered that the voltage regulation accuracy requirement is met;

[0087] Given a pressure stabilization time t1, that is, setting the pressure Pset to operate stably for t1 under the condition of |Pset-P5|≤δ;

[0088] Given the duration t2 during the test;

[0089] Given input parameter 2:

[0090] Open the solenoid valves: 3, 6, 7, 10, 12, 15, 16, 17;

[0091] Close solenoid valves: 1, 2, 4, 5, 8, 9, 11, 13 and 14;

[0092] Given input parameter 3:

[0093] Open solenoid valves: 10, 12, 15, 16, 17;

[0094] Close the solenoid valves: 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 14;

[0095] Given parameter 4:

[0096] Open the solenoid valves: 5, 6, 7, 8, 9, 11, 13, 14, 10, 12, 15, 16, 17;

[0097] Close the solenoid valves: 1, 2, 3, 4;

[0098] The above parameters are used to generate a test plan, which is then sent to the PLC to automatically complete the hydrogen chamber pressure holding test. The pressure drop at test time t2 can be obtained by collecting the pressure change from pressure sensor 6.

[0099] The airtightness testing of fuel cell stacks involves various types and requirements, and the testing process is quite cumbersome. This solution can meet all testing requirements and automatically complete the tests by generating test plans, making the tests accurate, fast, and stable. It greatly reduces tedious manual operations and avoids test errors caused by improper or inaccurate manual operation.

[0100] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0101] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units. The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

[0102] The specific embodiments of the invention have been described in detail above, but they are only examples, and this application is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of this application. Therefore, all equivalent changes, modifications, and improvements made without departing from the spirit and principles of this application should be covered within the scope of this application.

Claims

1. An automatic testing device for the airtightness of fuel cell stacks, characterized in that, Includes a media switching control unit, a pressure regulation unit, an airtightness testing unit, and a PLC controller; The medium switching control unit consists of four medium branches and a fifth solenoid valve, with all four medium branches connected to the fifth solenoid valve. The medium branch includes a helium-nitrogen mixed gas branch, a helium gas branch, a nitrogen gas branch, and a hydrogen gas branch; The helium-nitrogen mixed gas branch consists of a first manual ball valve, a first mechanical pressure reducing valve, a first filter, a first solenoid valve, a first pressure sensor, and a first check valve, which are connected in sequence. The helium branch consists of a second manual ball valve, a second mechanical pressure reducing valve, a second filter, a second solenoid valve, a second pressure sensor, and a second check valve, which are connected in sequence. The nitrogen branch consists of a third manual ball valve, a third mechanical pressure reducing valve, a third filter, a third solenoid valve, a third pressure sensor, and a third check valve, which are connected in sequence. The hydrogen branch consists of the fourth manual ball valve, the fourth mechanical pressure reducing valve, the fourth filter, the fourth solenoid valve, the fourth pressure sensor, and the fourth check valve, which are connected in sequence. The pressure regulating unit includes a pressure regulator and a fifth pressure sensor; The airtightness testing unit consists of 12 solenoid valves, 3 pressure sensors and a mass flow meter; The PLC controller is connected to the media switching control unit, the pressure regulation unit, and the airtightness testing unit, respectively.

2. The automatic testing device for the airtightness of a fuel cell stack as described in claim 1, characterized in that, The specific connection relationship of the airtightness testing unit is as follows: the output end of the pressure regulating unit is divided into two branches. The first branch is equipped with a sixth solenoid valve, and the second branch is equipped with a thirteenth solenoid valve, a mass flow meter, and a fifteenth solenoid valve. The pipeline between the mass flow meter and the fifteenth solenoid valve is connected to the pipeline after the sixth solenoid valve through the fourteenth solenoid valve. Then the first branch is divided into three branches leading to the test object. The hydrogen inlet branch is equipped with a seventh solenoid valve and a sixth pressure sensor in sequence. On the other side of the test object, there is a hydrogen outlet and an eighth solenoid valve. The air inlet branch is equipped with a ninth solenoid valve and a seventh pressure sensor in sequence. On the other side of the test object, there is an air outlet and a tenth solenoid valve. The coolant inlet branch is equipped with an eleventh solenoid valve and an eighth pressure sensor in sequence. On the other side of the test object, there is a coolant outlet and a twelfth solenoid valve. After flowing out of the test object, it leads to the second branch. The sixteenth solenoid valve connects to the thirteenth solenoid valve and the mass flow meter, and the seventeenth solenoid valve connects to the right side of the fifteenth solenoid valve.

3. The automatic testing device for the airtightness of a fuel cell stack as described in claim 1, characterized in that, Each of the aforementioned manual ball valves is used to manually control the opening and closing of each media branch.

4. The automatic testing device for the airtightness of a fuel cell stack as described in claim 1, characterized in that, Each of the aforementioned mechanical pressure reducing valves is used to adjust the pressure of each medium branch to 1 MPa for use by the testing device.

5. The automatic testing device for the airtightness of a fuel cell stack as described in claim 1, characterized in that, When the test is completed or the pressure is abnormal, the pressure is quickly released through the fifth solenoid valve.

6. The automatic testing device for the airtightness of a fuel cell stack as described in claim 1, characterized in that, The voltage regulator adjusts the output pressure using a 4-20mA current signal.

7. An automatic testing device for the airtightness of a fuel cell stack as described in claim 6, characterized in that, The pressure regulator uses a combination of feedforward and PID control to adjust the output pressure of the medium branch, thereby improving the accuracy of pressure regulation and control.

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