A method for compensating fuel cell stack assembly

Abstract

The present application relates to a kind of fuel cell stack assembly compensation method, method includes the following steps: S1, whether fuel cell stack is first assembly is judged;If no, then execute S2, if yes, then execute S3;S2, obtain the assembly force of the corresponding stack of assembly times, then execute S3;S3, determine the assembly force required to compensate size error, then execute S4;S4, whether fuel cell stack is first assembly is judged;If no, then execute S5, if yes, then execute S6;S5, the satisfaction degree of stack assembly quality is calculated based on the assembly force of the corresponding stack of assembly times, and according to the assembly force required to compensate size error, using fuel cell stack packaging structure is compensated;S6, assembly operation is carried out according to 20% compression rate, and according to the assembly force required to compensate size error, using fuel cell stack packaging structure is compensated.Compared with prior art, the present application has the advantages of improving stack assembly quality.

Description

Technical Field

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

[0002] A 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, offering advantages such as environmental friendliness, rapid start-up, and low operating temperature. It has broad application prospects in many fields, including transportation, aerospace, electronic equipment, and stationary power plants, and has become a research hotspot in both academic and industrial circles both domestically and internationally. To meet the requirements of output power and voltage, fuel cell stacks are typically assembled from hundreds of individual cells, clamped together by end plates. The assembly process is crucial to the consistency of the output performance of the fuel cell stack.

[0003] During fuel cell assembly, the compression state of the bipolar plate and membrane electrode assembly (MEA) interface affects the performance of the cell unit. On one hand, insufficient interface contact pressure leads to excessive contact resistance between the bipolar plate and MEA, increasing ohmic losses and affecting output voltage. On the other hand, excessive interface contact pressure causes over-compression or even damage to the gas diffusion layer, affecting water and gas transport. However, dimensional errors in key components such as bipolar plates and MEAs are unavoidable during manufacturing, resulting in deviations between the assembly force and design values ​​during fuel cell stack assembly, leading to variations in stack output performance. Furthermore, in practical applications, fuel cell stacks are repeatedly disassembled and reassembled due to reasons such as inadequate airtightness or component damage. The mechanical properties and dimensions of flexible components such as MEAs and sealing elements change under prolonged compression, and the assembly force decreases after reassembly, resulting in different stack output performance compared to the initial stage. Therefore, assembly compensation of the fuel cell stack can optimize assembly quality and improve output performance.

[0004] Chinese invention patent CN114204092A discloses a fuel cell endplate structure for improving internal pressure distribution in a fuel cell stack. This design incorporates grooves on the endplate and built-in springs to reduce uneven force distribution in the planar direction of individual cells within the stack, thus mitigating cell deflection in the normal direction. However, this structure cannot achieve precise and quantitative compensation for assembly forces. Chinese invention patent CN117013029A discloses a fuel cell stack pressure compensation device and control method. This method adds cylinder studs to the endplate of the stack and controls the piston top plate through pressure regulating valves and steering valves to apply pressure to the stack core, thereby achieving compensation. However, this method does not consider the impact of dimensional errors and assembly cycles on assembly forces, and therefore cannot truly achieve accurate and flexible compensation of fuel cell stack assembly forces. Summary of the Invention

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

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for assembling and compensating a fuel cell stack, comprising the following steps:

[0008] S1. Determine if the fuel cell stack is being assembled for the first time; if not, proceed to S2; if yes, proceed to S3.

[0009] S2. Obtain the number of assembly steps. Input the number of assembly steps into the equivalent model of the fuel cell stack to obtain the stack assembly force corresponding to the number of assembly steps, and then execute S3.

[0010] S3. Obtain the electrode size error, input the electrode size error into the fuel cell stack equivalent model, obtain the stack assembly force corresponding to the size error, determine the assembly force required to compensate for the size error based on the stack assembly force corresponding to the size error, and then execute S4.

[0011] S4. Determine if the fuel cell stack is being assembled for the first time; if not, proceed to S5; if yes, proceed to S6.

[0012] S5. Calculate the satisfaction of the stack assembly quality based on the stack assembly force corresponding to the number of assembly times, determine the optimal compression ratio when the satisfaction exceeds the threshold, perform the assembly operation according to the optimal compression ratio, and use the fuel cell stack packaging structure to compensate for the assembly force required to compensate for the size error.

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

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

[0015]

[0016] Where ΔF is the assembly force required to compensate for dimensional errors. This represents the calculation results of the equivalent model of the fuel cell stack with dimensional error as input. This represents the assembly force of the fuel cell stack corresponding to the dimensional error.

[0017] Furthermore, the satisfaction level with the fuel cell stack assembly quality is:

[0018]

[0019] in, Let be a satisfaction function of the contact resistance between the metal bipolar plate and the gas diffusion layer. D is a satisfaction function of the porosity of the gas diffusion layer. Tol Satisfaction with the quality of fuel cell 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 ε represents the stack assembly force corresponding to the i-th assembly attempt, and ε is the assembly force compression ratio; f1 and f2 are functions obtained by fitting the model calculation results and the experimental results of the gas diffusion layer conductivity.

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

[0024]

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

[0026] Furthermore, the inputs to the equivalent model of the fuel cell stack also include 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 custom tie rod, an adjustable screw, a nut, and a disc spring. The specific steps for compensation using the fuel cell stack packaging structure are to control the core compression amount by adjusting the nut of the adjustable screw.

[0028] Furthermore, the upper end plate and the first separate lower end plate are connected by a custom tie rod.

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

[0030] Furthermore, the disc spring is positioned between the first split lower end plate and the second split lower end plate.

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

[0032] This invention combines an equivalent model of a fuel cell stack with fuel cell stack assembly quality evaluation parameters to compensate for the stack assembly force under different dimensional error distributions and different assembly cycles, thereby improving the stack assembly quality. At the same time, this 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 requirements of mass production of fuel cell stacks. Attached Figure Description

[0033] Figure 1 This is a flowchart of the present invention;

[0034] Figure 2 The assembly force variation curves under different dimensional errors of the present invention are shown.

[0035] Figure 3 This is a curve showing the change in assembly satisfaction under different assembly cycles according to the present invention;

[0036] Figure 4 This is a schematic diagram of the packaging structure used to implement the fuel cell stack assembly compensation method;

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

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

[0039] Figure 7 A schematic diagram showing the connection between the custom pull rod and the adjustable screw;

[0040] Figure 8 This is a schematic diagram showing the connection between the second separate lower end plate and the adjustable screw.

[0041] In the diagram, 1-upper end plate, 2-first split lower end plate, 3-second split lower end plate, 4-customized pull rod, 5-adjustable screw, 6-nut, 7-disc spring. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0043] This invention proposes a fuel cell stack assembly compensation method, the flowchart of which is as follows: Figure 1As shown, the dimensions of fuel cell stack components and assembly process parameters are collected. Using an equivalent model of fuel cell stack assembly, the assembly force of the stack under different dimensional error distributions and different assembly cycles is predicted. Combined with fuel cell stack assembly quality evaluation parameters, the optimal assembly compression ratio required for the fuel cell stack is determined. Based on this, a fuel cell stack packaging structure with compensation function is designed, including an upper end plate, a separate lower end plate, a disc spring, and a customized tie rod with an embedded adjustable screw. This structure can not only compensate for different dimensional errors and different assembly cycles, but also ensure matching with the fuel cell stack packaging shell. Compared with existing technologies, this invention can ensure accurate and quantitative assembly compensation of the fuel cell stack without affecting mass production. The method of this invention includes the following steps:

[0044] S1. Determine if the fuel cell stack is being assembled for the first time; if not, proceed to S2; if yes, proceed to S3.

[0045] S2. Obtain the number of assembly steps. Input the number of assembly steps into the equivalent model of the fuel cell stack to obtain the stack assembly force corresponding to the number of assembly steps, and then execute S3.

[0046] S3. Obtain the electrode size error, input the electrode size error into the fuel cell stack equivalent model, obtain the stack assembly force corresponding to the size error, determine the assembly force required to compensate for the size error based on the stack assembly force corresponding to the size error, and then execute S4.

[0047] S4. Determine if the fuel cell stack is being assembled for the first time; if not, proceed to S5; if yes, proceed to S6.

[0048] S5. Calculate the satisfaction of the stack assembly quality based on the stack assembly force corresponding to the number of assembly times, determine the optimal compression ratio when the satisfaction exceeds the threshold, perform the assembly operation according to the optimal compression ratio, and use the fuel cell stack packaging structure to compensate for the assembly force required to compensate for the size error.

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

[0050] This invention reduces the impact of dimensional errors and assembly cycles on the fuel cell stack, optimizes the fuel cell stack assembly quality, and ensures the stability of the fuel cell stack output performance.

[0051] The specific steps for predicting the fuel cell assembly force under different dimensional error distributions and different assembly cycles are as follows:

[0052] Predicting the assembly force of the fuel cell stack under different dimensional errors: The point cloud data of the dimensional error is introduced into the equivalent model to construct an equivalent body of the bipolar plate reaction zone containing the dimensional error. The assembly force under different dimensional errors is calculated through the equivalent model of the fuel cell stack to 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 ratio.

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

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

[0055] The formulas for calculating the assembly force required for compensation under different dimensional error distributions are as follows:

[0056]

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

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

[0059] Predicting the assembly force of the fuel cell stack under different assembly cycles: Calculate the equivalent constitutive structure of the model electrode under different assembly cycles, and calculate the assembly force under different assembly cycles using the equivalent model of the fuel cell stack. Other input parameters of the model include: material parameters of other components, interface contact parameters between components, displacement boundary parameters, and assembly compression ratio.

[0060] Fuel cell stack assembly quality evaluation parameters: Using the contact resistance between the metal bipolar plates and the gas diffusion layer, and the porosity of the gas diffusion layer as response variables, the satisfaction level of the fuel cell stack assembly quality is calculated to obtain the optimal compression ratio under different assembly cycles. The calculation method for satisfaction level is as follows:

[0061]

[0062] Among them, D Tol The overall satisfaction level of the fuel cell stack assembly is represented by a value ranging from 0 to 1.

[0063] The satisfaction function of the contact resistance between the metal bipolar plate and the gas diffusion layer is related to the assembly compression ratio of the fuel cell stack.

[0064]

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

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

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

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

[0069]

[0070] Where 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 compression ratio:

[0072] V p =f4(ε)

[0073] The porosity satisfaction function 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 cycles in the predicted assembly force of the fuel cell stack under different assembly cycles is 5.

[0077] An overall satisfaction score of 0.85 for fuel cell stack assembly quality meets the assembly requirements.

[0078] By analyzing the assembly satisfaction variation curve, we can obtain the optimal assembly compression ratio and the acceptable compression ratio range for different assembly cycles.

[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 pull 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 to the custom tie rod 4 to ensure that the final height of the fuel cell stack is consistent with the design value and matches the fuel cell stack packaging shell.

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

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

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

[0084] 1) This invention establishes evaluation parameters for the assembly quality of fuel cell stacks, evaluates the assembly quality of the stacks, and can guide the optimization and improvement of the stack assembly process.

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

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

[0087] The following is an actual experiment:

[0088] Design an assembly to compensate for dimensional errors in a specific type of fuel cell stack. The stack contains 5 fuel cells.

[0089] First, the dimensional error of the reaction zone of the metal bipolar plate was obtained using laser testing. The average value of all measurement points was used as the classification criterion, and 10 categories were selected as the model error input. The error values ​​of the 10 categories are shown in Table 1 below:

[0090] Table 1. 10 types of error values

[0091]

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

[0093] The assembly force required to compensate is obtained by using the assembly force when the dimensional error is 0 as the design value.

[0094] Assembly force compensation is achieved through the fuel cell stack packaging structure, such as Figure 4 As shown.

[0095] First, the assembly is carried out with a 20% compression rate, and the upper end plate 1 is connected to the first separate lower end plate 2 by a custom tie rod 4.

[0096] The upper end plate 1 is connected to the second separate lower end plate 3 by adjusting the screw 5, and the assembly force is compensated by adjusting the nut 6.

[0097] A compensation design for the number of assembly cycles of a certain type of fuel cell stack.

[0098] First, calculate the equivalent constitutive structure of the membrane electrode during assembly 1 to 5 times.

[0099] The equivalent constitutive models of membrane electrodes under different assembly cycles are input into the equivalent assembly model of fuel cell stacks to calculate the assembly forces under different assembly cycles.

[0100] Using the contact resistance between the bipolar plate and the gas diffusion layer and the porosity of the gas diffusion layer as response variables, a curve showing the change in assembly quality satisfaction with compression ratio was constructed, such as... Figure 3 As shown, using 0.85 as the satisfaction index, the feasible compression ratio range and the optimal compression ratio under different assembly times were obtained.

[0101] Assembly force compensation is achieved through the fuel cell stack packaging structure, such as Figure 4 As shown.

[0102] First, the assembly is carried out with a 20% compression rate, and the upper end plate 1 is connected to the first separate lower end plate 2 by a custom tie rod 4.

[0103] The upper end plate 1 is connected to the second split lower end plate 3 via an adjustable screw 5, and the compression ratio is adjusted to the optimal value by adjusting the nut 6 to compensate for assembly forces caused by dimensional errors. A schematic diagram of the disc spring layout used to support the split lower end plate is shown below. Figure 5 As shown in the diagram. The connection between the upper plate and the adjustable screw is illustrated in the diagram. Figure 6 As shown; the connection diagram between the custom pull rod and the adjustable screw is as follows. Figure 7 As shown; the connection diagram of the second separate lower end plate and the adjustable screw is as follows. Figure 8 As shown.

[0104] This invention establishes an assembly force compensation method for dimensional errors of metal plates in fuel cells and designs a corresponding fuel cell stack packaging structure, which can meet the requirements of mass production packaging of fuel cell stacks. At the same time, it can compensate for assembly force for different dimensional error distributions, thereby improving the output performance and assembly quality of fuel cell stacks.

[0105] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A fuel cell stack assembly compensation method characterized by, The method comprises the following steps: S1, judging whether the fuel cell stack is assembled for the first time; if not, performing S2, if yes, performing S3; S2, obtaining the assembly times, inputting the assembly times into the fuel cell stack equivalent model to obtain the stack assembly force corresponding to the assembly times, and then performing S3; S3, obtaining the size error of the polar plate, inputting the size error of the polar plate into the fuel cell stack equivalent model to obtain 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 performing S4; S4, judging whether the fuel cell stack is assembled for the first time; if not, performing S5, if yes, performing S6; S5, calculating the satisfaction degree of the stack assembly quality based on the stack assembly force corresponding to the assembly times, determining the optimal compression rate when the satisfaction degree exceeds the threshold, performing the assembly operation according to the optimal compression rate, and compensating according to the assembly force required to compensate for the size error by using the fuel cell stack packaging structure; S6, performing the assembly operation according to the 20% compression rate, and compensating according to the assembly force required to compensate for the size error by using the fuel cell stack packaging structure.

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

3. A fuel cell stack assembly compensation method according to claim 1, wherein The satisfaction degree of the stack assembly quality is: wherein, is a satisfaction function for the contact resistance between the metal bipolar plate and the gas diffusion layer, is a satisfaction function for the porosity of the gas diffusion layer, D Tol is a satisfaction function for the quality of the stack assembly.

4. A fuel cell stack assembly compensation method according to claim 3, wherein The satisfaction function of the contact resistance between the metal bipolar plate and the gas diffusion layer is: where F i is the assembly force of the stack 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, wherein The satisfaction function of the porosity of the gas diffusion layer is: where V p is the gas diffusion layer pore volume, V is the total gas diffusion layer volume, and the gas diffusion layer porosity satisfaction function is a function related to the assembly force compressibility.

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

7. The method of claim 1, wherein, The fuel cell stack packaging structure comprises an upper end plate (1), a first split lower end plate (2), a second split lower end plate (3), a customized pull rod (4), an adjustable screw rod (5), a nut (6) and a disc spring (7). The specific steps of compensating by using the fuel cell stack packaging structure are to control the core compression amount by adjusting the nut (6) of the adjustable screw rod (5).

8. A fuel cell stack assembly compensation method according to claim 7, characterized by, The upper end plate (1) and the first split lower end plate (2) are connected by the customized pull rod (4).

9. A fuel cell stack assembly compensation method according to claim 8, wherein The upper end plate (1) and the second split lower end plate (3) are connected by the adjustable screw rod (5).

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

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