Fuel cell stack assembly compensation method

Abstract

The invention relates to a fuel cell stack assembly compensation method. The method comprises the following steps: S1, judging whether a fuel cell stack is assembled for the first time or not; if not, the step S2 is executed, and if yes, the step S3 is executed; s2, obtaining an electric pile assembling force corresponding to the assembling times, and then executing S3; s3, the assembly force needing to be compensated for by the size error is determined, and then the step S4 is executed; s4, judging whether the fuel cell stack is assembled for the first time or not; if not, the fifth step is executed, and if yes, the sixth step is executed; s5, calculating the satisfaction degree of the stack assembly quality based on the stack assembly force corresponding to the assembly times, and compensating by adopting a fuel cell stack packaging structure according to the assembly force required to be compensated by the size error; and S6, carrying out assembly operation according to a compression ratio of 20%, and carrying out compensation by adopting a fuel cell stack packaging structure according to the assembly force required to be compensated by the size error. Compared with the prior art, the method has the advantages of improving the assembly quality of the galvanic pile and the like.

Description

Technical Field

[0001] The invention relates to the technical field of proton exchange membrane fuel cells, and in particular to a fuel cell stack assembly compensation method. Background Art

[0002] Proton Exchange Membrane Fuel Cell (PEMFC) is an energy conversion device that directly converts hydrogen energy into electrical energy. The only reaction product is pure water. It has the advantages of being environmentally friendly, fast starting, and low operating temperature. It has broad application prospects in many fields such as transportation, aerospace, electronic equipment, and fixed power stations. It has become a research hotspot in academia and industry at home and abroad. In order to meet the requirements of output power and voltage, fuel cell stacks are usually assembled by stacking hundreds of single cells and clamped by end plates. The assembly process is the key to affecting the consistency of fuel cell stack output performance.

[0003] During the assembly process of fuel cells, the compression state of the interface between the bipolar plate and the membrane electrode affects the performance of the unit cell. On the one hand, too small an interface contact pressure leads to excessive contact resistance between the bipolar plate and the membrane electrode, increased ohmic loss, and affected output voltage; on the other hand, too large an interface contact pressure leads to excessive compression or even damage of the gas diffusion layer, affecting water and gas transmission. However, dimensional errors of key components such as bipolar plates and membrane electrodes cannot be avoided during the production process, resulting in deviations between the assembly force and the design value of the fuel cell stack during assembly, resulting in differences in the output performance of the stack. In addition, in actual applications, fuel cell stacks are repeatedly disassembled and assembled due to unqualified air tightness and component damage. The mechanical properties and dimensions of flexible components such as membrane electrodes and sealing elements change under long-term compression. The assembly force will also decay after reassembly, making the stack output performance different from the previous one. Therefore, assembly compensation for the stack can optimize the stack assembly quality and improve output performance.

[0004] Chinese invention patent CN114204092A discloses a fuel cell end plate structure for improving the internal pressure distribution of the stack. This solution opens a groove on the end plate and has a built-in spring to reduce the uneven force on the plane direction of the single cell in the stack and the problem of normal deflection of the battery, but this structure cannot achieve accurate and quantitative compensation of the assembly force. Chinese invention patent CN117013029A discloses a fuel cell stack pressure compensation device and control method. This solution adds a cylinder stud on the stack end plate, controls the piston top plate through the pressure regulating valve and the steering valve, applies pressure to the core, and then achieves the compensation effect. This method does not consider the influence of dimensional error and assembly times on the assembly force, and cannot truly achieve accurate and flexible compensation of the assembly force of the fuel cell stack. Summary of the invention

[0005] The purpose of the present invention is to provide a fuel cell stack assembly compensation method in order to reduce the impact of dimensional errors and assembly times on the stack, optimize the stack assembly quality, and ensure the stability of the stack output performance.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A fuel cell stack assembly compensation method, the method comprising the following steps:

[0008] S1, determine whether the fuel cell stack is assembled for the first time; if not, execute S2; if yes, execute S3;

[0009] S2, obtaining the number of assembly times, inputting the number of assembly times into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the number of assembly times, and then executing S3;

[0010] S3, obtaining the plate size error, inputting the plate size error into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the size error, determining the assembly force required to compensate for the size error based on the stack assembly force corresponding to the size error, and then executing S4;

[0011] S4, determining whether the fuel cell stack is assembled for the first time; if not, executing S5; if yes, executing S6;

[0012] S5. Calculate the satisfaction of the stack assembly quality based on the stack assembly force corresponding to the number of assemblies, determine the optimal compression rate when the satisfaction rate exceeds a threshold, perform assembly operations according to the optimal compression rate, and use the fuel cell stack packaging structure to compensate for the dimensional error according to the assembly force required to compensate for the dimensional error;

[0013] S6. Perform assembly operation according to a 20% compression rate, and use a fuel cell stack packaging structure to compensate for the assembly force required to compensate for the dimensional error.

[0014] Furthermore, the assembly force required to compensate for the dimensional error is:

[0015]

[0016] Where ΔF is the assembly force required to compensate for the dimensional error, It represents the calculation result of the equivalent model of the fuel cell stack when the size error is 0 as input. is the stack assembly force corresponding to the dimensional error.

[0017] Furthermore, the satisfaction of the stack assembly quality is:

[0018]

[0019] in, is the satisfactory function of the contact resistance between the metal bipolar plate and the gas diffusion layer, is the satisfaction function of the porosity of the gas diffusion layer, D Tol Satisfaction with the quality of stack assembly.

[0020] Furthermore, the satisfaction function of the contact resistance between the metal bipolar plate and the gas diffusion layer is:

[0021]

[0022] Among them, F i is the stack assembly force corresponding to the i-th assembly number, ε is the assembly force compression rate; f1 and f2 are functions obtained by fitting the model calculation results and the gas diffusion layer conductivity experimental results.

[0023] Furthermore, the satisfaction function of the porosity of the gas diffusion layer is:

[0024]

[0025] Among them, V p is the pore volume of the gas diffusion layer, V is the total volume of the gas diffusion layer, and the satisfaction function of the porosity of the gas diffusion layer is a function related to the assembly force compression rate.

[0026] Furthermore, the input of the fuel cell stack equivalent model also includes material parameters, interface contact parameters between components, displacement boundary parameters and assembly compression ratio.

[0027] Furthermore, the fuel cell stack packaging structure includes an upper end plate, a first separate lower end plate, a second separate lower end plate, a customized pull rod, an adjustable screw, a nut and a disc spring. The specific steps of using the fuel cell stack packaging structure for compensation are to control the core compression by adjusting the nut of the adjustable screw.

[0028] Further, the upper end plate and the first separated lower end plate are connected by a customized tie rod.

[0029] Furthermore, the upper end plate and the second separate lower end plate are connected via an adjustable screw.

[0030] Further, the disc spring is arranged between the first separate lower end plate and the second separate lower end plate.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention combines the fuel cell stack equivalent model and the fuel cell stack assembly quality evaluation parameters to compensate for the stack assembly force under different dimensional error distributions and different assembly times, thereby improving the stack assembly quality. At the same time, the present invention designs a stack packaging structure that matches the assembly force compensation method, adjusts the assembly force that needs to be compensated, and achieves accurate and flexible compensation of the assembly force while meeting the mass production requirements of the stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of the present invention;

[0034] Figure 2 It is the assembly force variation curve under different dimensional errors of the present invention;

[0035] Figure 3 is a curve showing the change of assembly satisfaction under different assembly times of the present invention;

[0036] Figure 4 A schematic diagram of a packaging structure for realizing a fuel cell stack assembly compensation method;

[0037] Figure 5 A schematic diagram of the layout of the disc springs used to support the separated lower end plate;

[0038] Figure 6 It is a schematic diagram of the connection between the upper end plate and the adjustable screw;

[0039] Figure 7 This is a schematic diagram of the connection between the custom pull rod and the adjustable screw;

[0040] Figure 8 is a schematic diagram of the connection between the second separated lower end plate and the adjustable screw;

[0041] In the figure, 1-upper end plate, 2-first separate lower end plate, 3-second separate lower end plate, 4-customized pull rod, 5-adjustable screw, 6-nut, 7-disc spring. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] The present invention proposes a fuel cell stack assembly compensation method, the flow chart of the method is as follows: Figure 1As shown, the dimensions and assembly process parameters of the stack components are collected, and the fuel cell stack assembly equivalent model is used to predict the stack assembly force under different dimensional error distributions and different assembly times. Combined with the fuel cell stack assembly quality evaluation parameters, the optimal assembly compression rate required for the fuel cell stack is determined. On this basis, a stack packaging structure with a compensating effect is designed, including an upper end plate, a separate lower end plate, a disc spring, and a customized pull rod with an embedded adjustable screw. This structure can not only perform assembly compensation for different dimensional errors and different assembly times, but also ensure matching with the stack packaging shell. Compared with the prior art, the present invention can ensure accurate and quantitative assembly compensation for the stack without affecting the mass production of the stack. The method of the present invention comprises the following steps:

[0044] S1, determine whether the fuel cell stack is assembled for the first time; if not, execute S2; if yes, execute S3;

[0045] S2, obtaining the number of assembly times, inputting the number of assembly times into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the number of assembly times, and then executing S3;

[0046] S3, obtaining the plate size error, inputting the plate size error into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the size error, determining the assembly force required to compensate for the size error based on the stack assembly force corresponding to the size error, and then executing S4;

[0047] S4, determining whether the fuel cell stack is assembled for the first time; if not, executing S5; if yes, executing S6;

[0048] S5. Calculate the satisfaction of the stack assembly quality based on the stack assembly force corresponding to the number of assemblies, determine the optimal compression rate when the satisfaction rate exceeds a threshold, perform assembly operations according to the optimal compression rate, and use the fuel cell stack packaging structure to compensate for the dimensional error according to the assembly force required to compensate for the dimensional error;

[0049] S6. Perform assembly operation according to a 20% compression rate, and use a fuel cell stack packaging structure to compensate for the assembly force required to compensate for the dimensional error.

[0050] The present invention reduces the influence of dimensional error and assembly times on the battery stack, optimizes the assembly quality of the battery stack, and ensures the stability of the output performance of the battery stack.

[0051] The specific steps to predict the stack assembly force under different size error distributions and different assembly times are as follows:

[0052] Predict the stack assembly force under different dimensional errors: Introduce the dimensional error point cloud data into the equivalent model, construct the bipolar plate reaction zone equivalent containing the dimensional error, calculate the assembly force under different dimensional errors through the fuel cell stack equivalent model, and obtain the assembly force compensation value under different dimensional errors; other input parameters of the model include: material parameters of other components, interface contact parameters between components, displacement boundary parameters and assembly compression rate.

[0053] The dimensional error is classified based on the average value of the dimensional error of all measuring points in the reaction area, and this is used as the model error input.

[0054] The model calculation result when the dimensional error is 0 is used as the design value of the assembly force

[0055] The calculation formula for the assembly force required to compensate for different dimensional error distributions is as follows:

[0056]

[0057] Among them, ΔF is the assembly force required to compensate for different dimensional errors;

[0058] The assembly force corresponding to different dimensional errors can be expressed by the model calculation results.

[0059] Predict the stack assembly force under different assembly times: Calculate the equivalent constitutive structure of the mold electrode under different assembly times, and calculate the assembly force under different assembly times through the fuel cell stack equivalent model. Other input parameters of the model include: material parameters of other components, interface contact parameters between components, displacement boundary parameters and assembly compression rate;

[0060] Evaluation parameters of battery stack assembly quality: The contact resistance between the metal bipolar plate and the gas diffusion layer and the porosity of the gas diffusion layer are used as response variables to calculate the satisfaction of the battery stack assembly quality and obtain the optimal compression rate under different assembly times. The calculation method of satisfaction is:

[0061]

[0062] Among them, D Tol The overall satisfaction with the stack assembly, ranging from 0 to 1;

[0063] is a satisfactory function of the contact resistance between the metal bipolar plate and the gas diffusion layer, which is related to the assembly compression rate of the stack:

[0064]

[0065] Among them, F iis the assembly force at the i-th assembly, ε is the assembly force compression rate; the functional relationships f1 and f2 can be obtained by fitting the model calculation results and the gas diffusion layer conductivity experimental results.

[0066] The upper and lower limits are related to the type of gas diffusion layer and the requirements of stack assembly.

[0067] The upper limit is 4.7 mΩ·cm 2 , the lower limit is 1.7mΩ·cm 2 .

[0068] is the satisfaction function of the porosity of the gas diffusion layer, which can be expressed as follows:

[0069]

[0070] Wherein, V is the total volume of the gas diffusion layer;

[0071] V p The pore volume of the gas diffusion layer is related to the assembly compressibility:

[0072] V p =f4(ε)

[0073] The satisfaction function of porosity can be obtained Representation method:

[0074]

[0075] The upper limit is 0.8 and the lower limit is 0.6.

[0076] The maximum number of assembly times in the predicted battery stack assembly force under different assembly times is 5.

[0077] When the overall satisfaction of the stack assembly quality is greater than 0.85, it meets the assembly requirements.

[0078] Through the assembly satisfaction curve, the optimal assembly compression rate and the acceptable compression rate range under different assembly times can be obtained.

[0079] The present invention also provides a fuel cell stack packaging structure for implementing the above method, the structure comprising an upper end plate 1, a first separate lower end plate 2, a second separate lower end plate 3, a custom tie rod 4, an adjustable screw 5, a nut 6 and a disc spring 7:

[0080] The upper end plate 1 and the first separate lower end plate 2 are connected with the customized pull rod 4 to ensure that the final height of the battery stack is consistent with the design value and matches the battery stack packaging shell.

[0081] The upper end plate 1 and the second separate lower end plate 3 are connected with the adjustable screw 5. The core compression is controlled by adjusting the nut 6. The press of the assembly platform feeds back the assembly force according to the compression to achieve assembly compensation.

[0082] The disc spring 7 is arranged between the first detachable lower end plate 2 and the second detachable lower end plate 3 to provide support for the second detachable lower end plate 3 .

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] 1) The present invention establishes fuel cell stack assembly quality evaluation parameters to evaluate the stack assembly quality, which can guide the optimization and improvement of the stack assembly process.

[0085] 2) By combining the fuel cell stack equivalent model and the fuel cell stack assembly quality evaluation parameters, the stack assembly force under different dimensional error distributions and different assembly times can be compensated, which can improve the stack assembly quality.

[0086] 3) A fuel cell stack packaging structure that matches the assembly force compensation method is designed to achieve accurate and flexible compensation of assembly force while meeting the mass production requirements of fuel cell stacks.

[0087] The following is the actual experiment:

[0088] The dimensional error assembly compensation design is carried out for a certain type of fuel cell stack. The number of battery cells is 5.

[0089] First, the laser test method is used to obtain the size error of the reaction area of ​​the metal bipolar plate used. The average value of all measurement points is used as the classification basis, and 10 categories are selected as model error inputs. The 10 error values ​​are shown in Table 1 below:

[0090] Table 1 10 types of error values

[0091]

[0092] The dimensional error is introduced into the equivalent assembly model of the fuel cell stack, and the assembly force under different errors is calculated, and then the dimensional error-assembly force variation curve is obtained, such as Figure 2 shown.

[0093] The assembly force when the dimensional error is 0 is used as the design value to obtain the assembly force required for compensation.

[0094] Assembly force compensation is performed through the battery stack packaging structure, such as Figure 4 shown.

[0095] First, the assembly is performed at a compression rate of 20%, and the upper end plate 1 is connected to the first separated lower end plate 2 through the customized tie rod 4.

[0096] The upper end plate 1 is connected to the second separate lower end plate 3 by means of an adjustable screw rod 5, and the nut 6 is adjusted to achieve assembly force compensation.

[0097] Compensation design for the number of assembly times for a certain type of fuel cell stack.

[0098] Firstly, the equivalent constitutive structure of the membrane electrode during 1 to 5 times of assembly is calculated.

[0099] The membrane electrode equivalent constitutive model under different assembly times is input into the equivalent assembly model of the fuel cell stack, and the assembly force under different assembly times is calculated.

[0100] The contact resistance between the bipolar plate and the gas diffusion layer and the porosity of the gas diffusion layer are used as response variables to construct the curve of assembly quality satisfaction with compression rate, such as Figure 3 As shown in the figure, taking 0.85 as the satisfaction index, the feasible compression rate range and the optimal compression rate under different assembly times are obtained.

[0101] Assembly force compensation is performed through the battery stack packaging structure, such as Figure 4 shown.

[0102] First, the assembly is performed at a compression rate of 20%, and the upper end plate 1 is connected to the first separated lower end plate 2 through the customized tie rod 4.

[0103] The upper end plate 1 is connected to the second separated lower end plate 3 by means of an adjustable screw 5, and the nut 6 is adjusted to adjust the compression ratio to the optimum and the assembly force to compensate for the dimensional error. Figure 5 The schematic diagram of the connection between the upper end plate and the adjustable screw is shown in Figure 6 As shown; the connection diagram of the custom pull rod and the adjustable screw is as shown Figure 7 As shown; the schematic diagram of the connection between the second separated lower end plate and the adjustable screw is as shown Figure 8 shown.

[0104] The present invention establishes an assembly force compensation method for the dimensional error of the fuel cell metal plate, and designs a corresponding fuel cell stack packaging structure, which can meet the requirements of mass production packaging of the stack, and at the same time can perform assembly force compensation for different dimensional error distributions, thereby improving the output performance and assembly quality of the fuel cell stack.

[0105] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A fuel cell stack assembly compensation method, characterized in that: The method comprises the following steps: S1, determine whether the fuel cell stack is assembled for the first time; if not, execute S2; if yes, execute S3; S2, obtaining the number of assembly times, inputting the number of assembly times into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the number of assembly times, and then executing S3; S3, obtaining the plate size error, inputting the plate size error into the fuel cell stack equivalent model, obtaining the stack assembly force corresponding to the size error, determining the assembly force required to compensate for the size error based on the stack assembly force corresponding to the size error, and then executing S4; S4, determining whether the fuel cell stack is assembled for the first time; if not, executing S5; if yes, executing S6; S5. Calculate the satisfaction of the stack assembly quality based on the stack assembly force corresponding to the number of assemblies, determine the optimal compression rate when the satisfaction rate exceeds a threshold, perform assembly operations according to the optimal compression rate, and use the fuel cell stack packaging structure to compensate for the dimensional error according to the assembly force required to compensate for the dimensional error; S6. Perform assembly operation according to a compression rate of 20%, and use the fuel cell stack packaging structure to compensate for the assembly force required to compensate for the dimensional error.

2. A fuel cell stack assembly compensation method according to claim 1, characterized in that: The assembly force required to compensate for the dimensional error is: Where ΔF is the assembly force required to compensate for the dimensional error, It represents the calculation result of the equivalent model of the fuel cell stack when the size error is 0 as input. is the stack assembly force corresponding to the dimensional error.

3. A fuel cell stack assembly compensation method according to claim 1, characterized in that: The satisfaction level of battery stack assembly quality is: in, is the satisfactory function of the contact resistance between the metal bipolar plate and the gas diffusion layer, is the satisfaction function of the porosity of the gas diffusion layer, D Tol Satisfaction with the quality of stack assembly.

4. A fuel cell stack assembly compensation method according to claim 3, characterized in that: The satisfactory function of the contact resistance between the metal bipolar plate and the gas diffusion layer is: Among them, F i is the stack assembly force corresponding to the i-th assembly number, ε is the assembly force compression rate; f1 and f2 are functions obtained by fitting the model calculation results and the gas diffusion layer conductivity experimental results.

5. A fuel cell stack assembly compensation method according to claim 4, characterized in that: The satisfaction function of the porosity of the gas diffusion layer is: Among them, V p is the pore volume of the gas diffusion layer, V is the total volume of the gas diffusion layer, and the satisfaction function of the porosity of the gas diffusion layer is a function related to the assembly force compression rate.

6. A fuel cell stack assembly compensation method according to claim 1, characterized in that: The input of the fuel cell stack equivalent model also includes material parameters, interface contact parameters between components, displacement boundary parameters and assembly compression ratio.

7. A fuel cell stack assembly compensation method according to claim 1, characterized in that: The fuel cell stack packaging structure comprises an upper end plate (1), a first separate lower end plate (2), a second separate lower end plate (3), a customized pull rod (4), an adjustable screw (5), a nut (6) and a disc spring (7). The specific steps of using the fuel cell stack packaging structure for compensation are to control the amount of core compression by adjusting the nut (6) of the adjustable screw (5).

8. A fuel cell stack assembly compensation method according to claim 7, characterized in that: The upper end plate (1) and the first separated lower end plate (2) are connected via a customized tie rod (4).

9. A fuel cell stack assembly compensation method according to claim 8, characterized in that: The upper end plate (1) and the second separated lower end plate (3) are connected via an adjustable screw rod (5).

10. A fuel cell stack assembly compensation method according to claim 8, characterized in that: The disc spring (7) is arranged between the first separated lower end plate (2) and the second separated lower end plate (3).

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