Cell stack of fuel cell and press fitting method thereof

Abstract

The invention provides a cell stack of a fuel cell and a press fitting method thereof. The method comprises the steps that key design parameters of a to-be-pressed cell stack are obtained, and the key design parameters comprise the bipolar plate material, the bipolar plate area, the sealing ring material and the number of single cells; based on the key design parameters, recommended press-fitting force of the battery to be press-fitted is determined through a predefined press-fitting force estimation model; and carrying out press fitting on the to-be-press-fitted cell stack according to the recommended press fitting force. According to the method, the bipolar plate material, the bipolar plate area, the sealing ring material and the number of single batteries are introduced as modeling bases, and the recommended press-fitting force is automatically output through the predefined press-fitting force estimation model, so that the problems of inconsistent press-fitting force setting and large product yield fluctuation caused by dependence on manual experience traditionally are solved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a fuel cell stack and its press-fitting method. Background Technology

[0002] As a highly efficient and clean energy conversion device, fuel cell systems directly convert the chemical energy of hydrogen and oxygen in the air into electrical energy through an electrochemical reaction, thus having broad application prospects in new energy vehicles, distributed power generation, and other fields. The fuel cell stack, as the core component of the fuel cell system, is the site of the chemical reaction between hydrogen and oxygen. Its structure consists of multiple individual cells connected in series through press-fitting. Therefore, the press-fitting quality of the fuel cell stack directly affects its sealing performance, electrical and thermal conductivity, and service life.

[0003] During the press-fitting process of battery stacks, it is necessary to determine the press-fitting force (i.e., the force used for press-fitting), which is one of the key parameters of the battery stack press-fitting process. Current methods for determining the press-fitting force rely on the individual operational experience of engineers, lacking a unified quantitative standard. However, this experience-based approach has significant drawbacks, such as differences in judgment among different engineers, leading to poor consistency in press-fitting forces across different battery stacks and large fluctuations in product yield. Therefore, there is an urgent need for an objective, accurate, and scalable press-fitting solution. Summary of the Invention

[0004] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a fuel cell stack and its press-fitting method, which aims to solve the technical problems in the related technology to a certain extent.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This application provides a method for pressing and mounting a fuel cell stack, including:

[0007] Obtain the key design parameters of the battery stack to be press-assembled, including bipolar plate material, bipolar plate area, sealing ring material, and number of single cells;

[0008] Based on the key design parameters, the recommended pressing force for the battery to be pressed is determined by a predefined pressing force estimation model.

[0009] The battery stack to be press-fitted is press-fitted according to the recommended pressing force.

[0010] Preferably, the method further includes:

[0011] The pressing force estimation model is determined by taking the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells as single variables and controlling for single variables.

[0012] Preferably, the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells are each treated as a single variable, and the pressing force estimation model is determined by controlling for single variables, specifically as follows:

[0013] Based on the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells, a parametric finite element model of the fuel cell stack is established using the single variable control method.

[0014] The bipolar plate material, bipolar plate area, sealing ring material, and number of single cells were each treated as a single variable. By changing the single variable, multiple simulations were performed in the finite element model to obtain multiple sets of parameter combinations and corresponding simulation pressing force and stack performance data.

[0015] Using regression methods, a functional relationship is established between the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells and the simulated pressing force, which serves as the pressing force estimation model.

[0016] Preferably, after generating the press-fit force estimation model, the method further includes:

[0017] Based on a set of key design parameters used for verification, the predicted pressing force is obtained through the pressing force estimation model.

[0018] An actual pressing experiment was conducted using the predicted pressing force to obtain a fuel cell stack sample;

[0019] Measure the fuel cell stack performance data of the fuel cell stack sample;

[0020] When the fuel cell stack performance data is lower than a preset threshold, the pressing force estimation model is corrected.

[0021] Preferably, the number of single batteries is less than or equal to a preset number; and,

[0022] The battery stack to be pressed is pressed according to the recommended pressing force, specifically including:

[0023] When the press-fitting equipment is controlled to press-fit with the recommended press-fitting force as the target value, the actual press-fitting force applied to the battery stack to be press-fitted is monitored in real time by a pressure sensor.

[0024] The actual pressing force is compared with the target value, and the output of the actuator is dynamically adjusted according to the comparison result to stabilize the actual pressing force within the allowable error range of the target value.

[0025] Preferably, the method further includes:

[0026] During the pressing process, the compression displacement of the battery stack to be pressed is monitored in real time;

[0027] Establish a real-time relationship curve between actual pressing force and compression displacement, and compare the real-time relationship curve with a pre-stored reference curve, wherein the reference curve reflects the correspondence between reference force and compression displacement;

[0028] When the real-time relationship curve deviates from the reference curve, the pressing force is dynamically fine-tuned to make the actual curve follow the reference curve.

[0029] Preferably, the number of individual cells is greater than a preset number; and, pressing the battery stack to be pressed according to the recommended pressing force specifically includes:

[0030] The pressing force is increased to the first pressure value at the first preset speed and pressure is maintained for the first time period;

[0031] After the first period of pressure holding, the pressing force is increased to the recommended pressing force at a second preset speed and the second period of pressure holding is performed; wherein, the first pressure value is 50%-80% of the recommended pressing force, and the first preset speed is less than the second preset speed.

[0032] Preferably, during the pressing process of the battery stack to be pressed according to the recommended pressing force, the method further includes:

[0033] Temperature data is acquired in real time by a temperature sensor, wherein the temperature data includes at least one of the ambient temperature and the temperature of the battery stack to be pressurized;

[0034] When the monitored temperature data is lower than a first preset threshold, the pressing equipment is controlled to add a positive compensation force based on the recommended pressing force; or,

[0035] When the temperature data is detected to be higher than the second preset threshold, the pressing equipment is controlled to reduce the negative compensation force based on the recommended pressing force.

[0036] Preferably, after pressing the battery stack to be pressed according to the recommended pressing force, the method further includes: maintaining the recommended pressing force for a preset holding time, controlling the actuator to depressurize to a preset maintenance pressure, and tightening the screws.

[0037] This application provides a fuel cell stack for a fuel cell system, which is obtained by press-fitting using the method provided in this application.

[0038] Based on the above technical solution, the advantages of the present invention compared with the prior art are as follows:

[0039] The fuel cell stack press-fit method provided in this application includes obtaining key design parameters of the fuel cell stack to be press-fitted, including bipolar plate material, bipolar plate area, sealing ring material, and number of individual cells. Then, based on these key design parameters, a recommended press-fit force is determined using a predefined press-fit force estimation model. Finally, the fuel cell stack is press-fitted according to this recommended press-fit force. This method solves the problems of inconsistent press-fit force settings and large fluctuations in product yield caused by traditional methods that rely on manual experience, because it introduces bipolar plate material, bipolar plate area, sealing ring material, and number of individual cells as modeling criteria and automatically outputs the recommended press-fit force through a predefined press-fit force estimation model. Attached Figure Description

[0040] Figure 1 A detailed structural schematic diagram of the battery stack in a fuel cell system in the prior art;

[0041] Figure 2 This is a schematic diagram illustrating the specific process of the fuel cell stack pressing method provided in this application. Detailed Implementation

[0042] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0044] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] As mentioned earlier, the fuel cell stack is the core component of a fuel cell system. Its structure consists of multiple individual cells connected in series through press-fitting. Therefore, the press-fitting quality of the fuel cell stack directly affects its sealing performance, electrical and thermal conductivity, and service life. Determining the press-fitting force is crucial during the fuel cell stack press-fitting process, and this is one of the key parameters of the process. Current methods for determining the press-fitting force rely on the individual operational experience of engineers, lacking a unified quantitative standard. However, this experience-based approach has significant drawbacks. For example, different engineers may make different judgments, leading to poor consistency in the press-fitting force across different fuel cell stacks and large fluctuations in the yield of fuel cell stack products.

[0046] For example, if the pressing force is too small, it may cause air leakage in the battery stack, affecting its sealing performance; conversely, if the pressing force is too large, it may cause the bipolar plates to deform or break, affecting their service life.

[0047] Based on this, embodiments of this application provide a fuel cell stack and its press-fitting method, which can be used to solve the problems in the prior art. For ease of understanding, the structure of the fuel cell stack in the fuel cell system can be briefly described here, such as... Figure 1 The diagram shows a schematic of the structure of a fuel cell stack 10 in a fuel cell system. The stack 10 includes multiple individual cells 11 connected in series. These individual cells 11 are connected in series to form the stack 10 by press fitting. In practical applications, the structure of each individual cell 11 includes a bipolar plate, a membrane electrode assembly, and a sealing ring. The bipolar plate has hydrogen flow channels, air flow channels, and cooling water flow channels. The membrane electrode assembly includes a proton exchange membrane and a catalyst.

[0048] like Figure 2The diagram shown is a schematic flowchart of a fuel cell stack pressing method provided in an embodiment of this application. The method includes the following steps:

[0049] Step S21: Obtain the key design parameters of the battery stack to be pressurized.

[0050] The key design parameters include bipolar plate material, bipolar plate area, sealing ring material, and number of individual cells. As mentioned above, the structure of a single cell includes bipolar plates; therefore, the bipolar plate material in this key design parameter refers to the material of the bipolar plates within the single cell. In practical applications, common bipolar plate materials include graphite, metal, or composite materials. Different materials have different elastic moduli, yield strengths, and compression rebound characteristics, directly affecting their deformation behavior under pressure. For example, metal bipolar plates have high stiffness but are prone to plastic deformation, while graphite plates, although brittle, have good compressive stability. Therefore, accurately identifying the bipolar plate material helps in the reasonable assessment of its compressive strength.

[0051] The bipolar plate area, a key design parameter, refers to the effective projected area involved in gas distribution and current transmission, typically measured in square centimeters (cm²). A larger area results in a higher total force under the same unit pressure, while also increasing the length of the sealing interface, placing higher demands on the uniformity of the seal ring's compression. This parameter affects the overall pressure required and the uniformity of pressure distribution.

[0052] The sealing ring, a key design parameter, is used to fill the sealing gaps between individual cells, preventing cross-leakage of hydrogen, oxygen, and coolant. In practical applications, common sealing ring materials include silicone rubber, ethylene propylene diene monomer (EPDM), and fluororubber (FKM). These different materials exhibit significant differences in hardness, compression set, resilience, and temperature adaptability. For example, EPDM has excellent high-temperature resistance, making it suitable for high-temperature operating conditions; while silicone rubber has good resilience, making it suitable for scenarios requiring frequent disassembly and reassembly. The material of the sealing ring directly determines the minimum effective sealing pressure and the maximum permissible compression limit.

[0053] The number of individual cells refers to the number of individual cells connected in series in the battery stack, which directly affects the total stack thickness, end plate deformation trend, and overall contact resistance. As the number of individual cells increases, the cumulative compression increases. Insufficient pressing force may lead to poor contact of the middle cells; conversely, excessive pressing force may cause the end components to be subjected to excessive stress. Therefore, the number of individual cells is one of the key variables determining the scale of the total pressing force.

[0054] The four parameters mentioned above together constitute the core set of design variables affecting the press-fit behavior of battery stacks. They do not act independently but rather through a coupling effect generated by structural mechanics and interface contact mechanisms. For example, when using a highly resilient sealing ring material, even if the bipolar plate area is large, the press-fit force per unit area can be appropriately reduced; however, when there are a large number of individual cells, even if a softer sealing ring is used, the total press-fit force needs to be increased to compensate for the accumulated compression loss.

[0055] Furthermore, the battery stack to be press-fitted in step S21 can be any battery stack. Since the battery stack needs to be press-fitted later, it is referred to as the battery stack to be press-fitted. For the specific implementation of step S21, the design files of the battery stack to be press-fitted can be obtained, such as the CAD drawings, design data, digital models, etc. of the battery stack to be press-fitted, and then the key design parameters of the battery stack to be press-fitted can be extracted from these design files.

[0056] Step S22: Based on this key design parameter, determine the recommended pressing force for the battery to be pressed using a predefined pressing force estimation model.

[0057] The predefined pressing force estimation model serves to determine the recommended pressing force for the battery to be pressed, based on key design parameters, namely the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells. This model can be pre-generated by treating each of the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells as a single variable. The pressing force estimation model is determined using the single-variable method. This method modifies only one design parameter at a time while keeping the other key design parameters constant, thus measuring multiple sets of data. This allows for a systematic study of the independent influence of each input variable on the required pressing force, providing data support for establishing a scientific and interpretable mathematical model.

[0058] One method for determining the pressing force estimation model by treating bipolar plate material, bipolar plate area, sealing ring material, and number of single cells as individual variables can be implemented as follows: First, a parametric finite element model of the fuel cell stack is established based on the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells using the controlled single variable method. Then, by changing each of these individual variables, multiple simulations are performed in the finite element model to obtain multiple sets of parameter combinations and corresponding simulated pressing force and stack performance data. Finally, a regression method is used to establish the functional relationship between the bipolar plate material, bipolar plate area, sealing ring material, number of single cells, and simulated pressing force, which serves as the pressing force estimation model.

[0059] This finite element model includes the spatial arrangement, contact relationships, and mechanical boundary conditions of each layer of components in the battery stack (such as bipolar plates, membrane electrodes, and sealing rings). It supports parameterized input of different material properties (such as elastic modulus and Poisson's ratio), geometric dimensions (such as effective area and thickness), and the number of stacked layers. For example, bipolar plates can be made of graphite, metal, or composite materials, and their corresponding material parameters can be preset as adjustable fields in the model. Sealing rings can be made of silicone rubber, ethylene propylene diene monomer (EPDM), or fluororubber (FKM), each with an independent hyperelastic constitutive model (such as the Mooney-Rivlin or Ogden model) to accurately simulate compression and springback behavior. This parameterized modeling approach allows the same model framework to be used for simulation analysis of battery stacks with various configurations, significantly improving modeling efficiency and reusability.

[0060] Furthermore, in practical applications, this parametric finite element model can be implemented using commercial simulation software (such as ANSYS and Abaqus), or a script-driven modeling process can be independently developed based on an open-source solver (such as Code_Aster). During the modeling process, mesh generation strategies, contact algorithms, and boundary constraints (such as a fixed bottom surface and axial displacement or force load applied to the top surface) can be set as needed to ensure the simulation results have engineering credibility.

[0061] After obtaining the parameterized finite element model of the fuel cell stack, the bipolar plate material, bipolar plate area, sealing ring material, and number of cells can be treated as single variables. Multiple simulations can be performed in the finite element model by changing these single variables to obtain multiple sets of parameter combinations and corresponding simulated pressing force and stack performance data. The aim is to systematically explore the influence of each key parameter using the controlled variable method. In each simulation, only one parameter is allowed to change, while the remaining parameters remain at their baseline values, thus isolating the independent influence trend of that parameter on the pressing force requirement. For example, when studying the influence of the bipolar plate area, with the material fixed as titanium alloy, the sealing ring as EPDM, and the number of cells as 80, the effective bipolar plate area is gradually increased from 200 cm² to 600 cm², and the required total pressing force is recorded. Similarly, when examining the influence of the sealing ring material, while keeping other parameters consistent, three materials are successively replaced: silicone, EPDM, and FKM, and the differences in reaction force generated under the same compression are compared. Through such systematic simulation experiments, a database covering typical operating conditions is generated, including but not limited to: maximum contact stress distribution under different combinations, seal ring compression ratio, interlaminar slip risk index, overall stiffness response curve, and other fuel cell stack performance indicators. Ultimately, in this way, multiple sets of parameter combinations and corresponding simulated pressing forces and fuel cell stack performance data can be obtained.

[0062] After obtaining multiple sets of parameter combinations and corresponding simulated pressing force and stack performance data, regression methods can be used to establish a functional relationship between bipolar plate material, bipolar plate area, sealing ring material, and the number of single cells and the simulated pressing force. This relationship serves as a pressing force estimation model. Regression methods can include multiple linear regression, multinomial regression, support vector regression (SVR), or neural network regression, with the specific choice depending on the degree of nonlinearity of the data and the precision of the functional relationship, which serves as the accuracy requirement for the pressing force estimation model. In practical applications, this functional relationship, i.e., the pressing force estimation model, can be ultimately obtained through curve fitting and other methods.

[0063] Furthermore, after obtaining the pressing force estimation model, it can be further verified. For example, based on a set of key design parameters used for verification, the predicted pressing force can be obtained through the pressing force estimation model. During the verification process, the set of key design parameters used for verification can be input into the pressing force estimation model to predict the pressing force. Then, an actual pressing experiment is conducted with the predicted pressing force to obtain a fuel cell stack sample. The fuel cell stack performance data of the sample is then measured, including the sealing data, volt-ampere cycle curve, and other output performance data. When the fuel cell stack performance data is lower than a preset threshold, the pressing force estimation model can be further corrected. This process of feedback and correction is used to optimize the pressing force estimation model, ultimately resulting in an optimized pressing force estimation model.

[0064] Step S23: Press the battery stack to be pressed according to the recommended pressing force.

[0065] In this application, pressing according to the recommended pressing force refers to using pressing equipment (such as a hydraulic press, servo press, etc.) to accurately apply the calculated recommended pressing force to the end plates at both ends of the battery stack to be pressed, so that the entire stack is uniformly compressed in the axial direction, ensuring good electrical connection and sealing integrity between individual cells.

[0066] Furthermore, the pressing process can be carried out at room temperature or in a temperature-controlled environment. The pressing equipment is equipped with force sensors and displacement sensors to provide real-time feedback on the actual loading force and compression stroke, thereby achieving closed-loop control. After pressing is completed, the screws are usually tightened to maintain a stable clamping force over a long period.

[0067] Specifically, in step S23, the compression displacement of the battery stack can be monitored in real time during the pressing process. This compression displacement reflects the total compression of each individual cell (e.g., how many millimeters it has been compressed). Then, a real-time relationship curve between the actual pressing force and the compression displacement is established, and the real-time relationship curve is compared with a pre-stored reference curve. The reference curve reflects the correspondence between the reference force and the compression displacement. When the real-time relationship curve deviates from the reference curve, the actual pressing force is dynamically fine-tuned so that the actual curve follows the reference curve.

[0068] During the pressing process, the compression displacement of the battery stack is monitored in real time. This is achieved by continuously collecting the axial compression deformation of the battery stack under pressure using displacement sensors or measuring devices such as optical scales installed in the pressing equipment. This compression displacement reflects the deformation response characteristics of the overall battery stack structure under external forces, including the elastic compression, plastic deformation, and contact sealing process of multilayer composite materials such as bipolar plates, membrane electrodes, and sealing rings. The displacement sensor can be integrated into the moving pressure head or fixed bracket of the pressing machine, featuring high precision (e.g., resolution of ±1μm) and high sampling frequency (e.g., ≥100Hz) to ensure the real-time performance and accuracy of the data.

[0069] A real-time relationship curve between actual pressing force and compression displacement is established. This can be achieved by simultaneously acquiring the actual pressing force value output by the pressure sensor and the compression displacement value fed back by the displacement sensor, constructing a functional mapping relationship between the two with time as a common variable, and plotting it as a two-dimensional curve. The horizontal axis represents compression displacement, and the vertical axis represents actual pressing force. This curve characterizes the mechanical behavior path of the battery stack during the pressing process, and its slope changes according to the stiffness response at different stages: the initial stage is characterized by a low-slope pre-tightening contact section, followed by a linear elastic section, and finally a gentle compaction saturation section. Under normal assembly conditions, this curve should exhibit a stable and repeatable trend, with good batch consistency.

[0070] The real-time relationship curve is compared with a pre-stored benchmark curve. The benchmark curve is a typical force-displacement response curve obtained from the press-fitting of historical qualified battery stacks under standard process parameters. After data normalization, it is stored in the control system database. The benchmark curve can be templated by statistically analyzing the average curve of multiple successful samples and setting an allowable fluctuation range (such as ±5% deviation band) for online quality judgment. The comparison process is executed in real time by the control unit, and the similarity assessment of asynchronous curves is achieved by curve fitting degree calculation (such as least squares error), feature point matching (such as inflection point position, maximum slope point), or dynamic time warping (DTW) algorithm.

[0071] Specifically, when the real-time relationship curve deviates from the reference curve, the pressing force is dynamically fine-tuned. This means that once the real-time relationship curve is detected to exceed the preset tolerance range or exhibit an abnormal trend (such as premature saturation, a sudden drop in slope, or abnormal rebound), an adjustment mechanism can be triggered. This mechanism adjusts the output torque of the hydraulic cylinder or servo motor through closed-loop feedback, achieving adaptive correction of the pressing force. For example, if the real-time curve is generally below the reference curve and the slope is low, it may indicate that the sealing ring is aging, damaged, or improperly assembled, resulting in insufficient compression stiffness. In this case, the system can automatically increase a certain proportion of compensation pressure (such as +3%~8% of the recommended pressing force) to ensure effective sealing. Conversely, if the curve rises rapidly and reaches the plateau region prematurely, it indicates possible foreign object inclusion or component misalignment. The system can then pause pressurization and issue an alarm signal to prevent over-compression and damage to the membrane electrode.

[0072] In this way, during the pressing process in step S23, the compression displacement of the battery stack is monitored in real time and a real-time relationship curve is established. Then, the real-time relationship curve is compared with the reference curve to dynamically fine-tune the actual pressing force, so that the actual curve follows the reference curve. This dynamic fine-tuning mechanism is used to make fine adjustments and corrections, and the pressing force is more precisely controlled. This can further improve the pressing consistency and product yield, effectively prevent the generation of batch defective products, and enhance the robustness and traceability of the production process.

[0073] Through the above-described steps, this application implements a method for press-fitting a fuel cell stack. This method includes obtaining key design parameters of the stack to be press-fitted, including bipolar plate material, bipolar plate area, sealing ring material, and the number of individual cells. Then, based on these key design parameters, a recommended press-fitting force is determined using a predefined press-fitting force estimation model. Finally, the stack is press-fitted according to this recommended force. This method, by introducing bipolar plate material, bipolar plate area, sealing ring material, and the number of individual cells as modeling criteria, and automatically outputting the recommended press-fitting force through a predefined press-fitting force estimation model, solves the problems of inconsistent press-fitting force settings and large fluctuations in product yield caused by traditional reliance on manual experience. Therefore, it not only improves the repeatability and controllability of the press-fitting process but also enhances the process adaptability between stacks of different specifications, which is conducive to promoting the intelligent and standardized development of fuel cell manufacturing. Therefore, the press-fitting method provided in this application achieves accurate prediction and execution of press-fitting force through quantitative acquisition and modeling of key design parameters, which significantly improves the consistency and reliability of battery stack assembly quality. It is applicable to various types and scales of fuel cell production scenarios and has good industrial application prospects.

[0074] It should be further explained that as the number of individual cells increases, the specific pressing process usually needs to be dynamically adjusted. For example, when the number of individual cells is less than or equal to a preset number (usually 100 cells), the number of individual cells is relatively small, and they can be directly pressed into shape in one step. However, when the number of individual cells is greater than the preset number, the number of individual cells is relatively large, and direct pressing into shape in one step can easily lead to uneven stress. Therefore, a multi-step pressing process can be adopted. Thus, the specific implementation of step S23 can be as follows: first, determine whether the number of individual cells is greater than the preset number. If the number of individual cells is less than or equal to the preset number, step S23 can specifically include: when controlling the actuator of the pressing equipment to press with the recommended pressing force as the target value, the actual pressing force applied to the battery stack is monitored in real time by a pressure sensor; the actual pressing force is compared with the target value, and the output of the actuator is dynamically adjusted according to the comparison result to stabilize the actual pressing force within the allowable error range of the target value.

[0075] The fact that the number of individual cells is less than or equal to the preset number indicates that the number of individual cells in the battery stack structure to be press-fitted is in a low range. This situation typically corresponds to small-to-medium power fuel cell systems, such as those used in light vehicles, portable power sources, or backup power sources. Because the overall size of the battery stack is small and the stiffness distribution is relatively uniform, it can be press-fitted in a single process.

[0076] Thus, when controlling the actuator of the pressing equipment to perform pressing with the recommended pressing force as the target value, the target value is the recommended pressing force output by the pressing force estimation model. Its unit is typically kilonewtons (kN), and the value depends on factors such as the bipolar plate area, the material's elastic modulus, the sealing ring compression characteristics, and the number of individual cells. This step emphasizes that this target value should always be used as the control benchmark throughout the entire pressing process to ensure that the final contact pressure meets the design requirements.

[0077] In practical applications, the actual pressing force applied to the battery stack can be monitored in real time using pressure sensors. These sensors can be positioned between the actuator and the upper end plate, or integrated within the pressing fixture. Comparing the actual pressing force with the target value and dynamically adjusting the actuator's output based on the comparison result describes a typical closed-loop control logic. The system receives the actual pressure value from the pressure sensor, calculates the deviation from the target value, and then generates corresponding drive commands based on a preset control algorithm (such as PID control, fuzzy control, or adaptive control). This adjusts the actuator's power input (such as solenoid valve opening, motor speed, or pump flow rate), thereby changing the output force. When the detected actual pressure is lower than the target value, the drive force is increased to raise the pressure; conversely, the output is reduced to prevent overpressure. This process continues until the pressure enters the allowable error range and remains stable.

[0078] Maintaining the actual pressing force within the allowable error range of the target value indicates not only pressure tracking but also the need to maintain steady-state control over a long period. The allowable error range can be defined according to product specifications, such as ±2% or ±5% of the target pressure value. Once the actual pressure enters this range, the system can switch to a pressure-holding mode, continuing to fine-tune the output to offset the effects of leakage, creep, or temperature changes, ensuring that pressure fluctuations do not exceed the threshold throughout the pressure-holding period. This state signifies that the pressing process has reached its end point, creating conditions for subsequent fastening or transfer procedures.

[0079] Of course, when the number of individual cells exceeds the preset number, the battery stack becomes larger, resulting in more module layers, more complex interlayer contact states, and longer stress transmission paths. If a one-time rapid pressurization method is used, it can easily lead to problems such as local stress concentration, bipolar plate misalignment, excessive compression of sealing rings, or even rupture, affecting the overall performance and lifespan of the battery stack. In this case, a multi-step pressurization process can be adopted. Therefore, in step S23, the battery stack to be pressurized is pressurized according to the recommended pressurization force. The specific implementation method is as follows: first, the pressurization force is increased to a first pressure value at a first preset speed and pressure is maintained for a first period of time. Then, after maintaining pressure for the first period of time, the pressurization force is increased to the recommended pressurization force at a second preset speed and pressure is maintained for a second period of time. The first pressure value is 50%-80% of the recommended pressurization force, and the first preset speed is less than the second preset speed.

[0080] In this multi-step pressing process, the pressing force is first increased to a first pressure value (which is less than the recommended pressing force) at a relatively slow speed (i.e., the first preset speed) and then held under pressure to pre-press each cell and reduce the gap between them. Then, the pressure is increased to the recommended pressing force at a relatively fast speed (i.e., the second preset speed). This allows for more uniform force distribution among the cells when there are a large number of cells.

[0081] In addition, considering the thermal expansion and contraction effect of materials, during the pressing process in step S23 of this application, the pressing force can be further corrected by incorporating temperature. Therefore, during the pressing process of the battery stack to be pressed according to the recommended pressing force, the method can also include acquiring temperature data in real time through a temperature sensor, wherein the temperature data includes at least one of ambient temperature and temperature of the battery stack to be pressed; at this time, when the temperature data is detected to be lower than a first preset threshold, it indicates that the temperature is too low, and the pressing equipment can be controlled to add a positive compensation force based on the recommended pressing force; or, when the temperature data is detected to be higher than a second preset threshold, it indicates that the temperature is too high, and the pressing equipment can be controlled to reduce a negative compensation force based on the recommended pressing force.

[0082] This method corrects the recommended pressing force to avoid fluctuations in the elastic modulus of the sealing material and the dimensional stability of metal components caused by temperature changes, which could affect the contact pressure distribution and sealing reliability. Thus, it increases pressure at low temperatures to ensure seal integrity and appropriately reduces pressure at high temperatures to avoid structural damage, ultimately achieving consistent pressing across the entire temperature range.

[0083] In addition, after pressing the battery stack to be pressed according to the recommended pressing force, the pressing of the battery stack to be pressed is completed. The method may further include maintaining the recommended pressing force for a preset holding time, controlling the actuator to depressurize to a preset maintenance pressure, and tightening the screws to bolt the battery stack to be pressed, thereby realizing the assembly of the battery stack to be pressed.

[0084] Based on the above embodiments, this embodiment further provides: a battery stack for a fuel cell system, which is a product assembled using any of the aforementioned press-fitting methods. Therefore, this battery stack can also solve the problems in the prior art, which will not be elaborated here.

[0085] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A method for press-fitting a fuel cell stack, characterized in that, include: Obtain the key design parameters of the battery stack to be press-assembled, including bipolar plate material, bipolar plate area, sealing ring material, and number of single cells; Based on the key design parameters, the recommended pressing force for the battery to be pressed is determined by a predefined pressing force estimation model. The battery stack to be press-fitted is press-fitted according to the recommended pressing force.

2. The method according to claim 1, characterized in that, The method further includes: The pressing force estimation model is determined by taking the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells as single variables and controlling for single variables.

3. The method according to claim 2, characterized in that, By treating the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells as individual variables, the pressing force estimation model is determined using the controlled single variable method, specifically as follows: Based on the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells, a parametric finite element model of the fuel cell stack is established using the single variable control method. The bipolar plate material, bipolar plate area, sealing ring material, and number of single cells were each treated as a single variable. By changing the single variable, multiple simulations were performed in the finite element model to obtain multiple sets of parameter combinations and corresponding simulation pressing force and stack performance data. Using regression methods, a functional relationship is established between the bipolar plate material, bipolar plate area, sealing ring material, and number of single cells and the simulated pressing force, which serves as the pressing force estimation model.

4. The method according to claim 3, characterized in that, After generating the press-fit force estimation model, the method further includes: Based on a set of key design parameters used for verification, the predicted pressing force is obtained through the pressing force estimation model. An actual pressing experiment was conducted using the predicted pressing force to obtain a fuel cell stack sample; Measure the fuel cell stack performance data of the fuel cell stack sample; When the fuel cell stack performance data is lower than a preset threshold, the pressing force estimation model is corrected.

5. The method according to claim 1, characterized in that, The number of single batteries is less than or equal to a preset number; as well as, The battery stack to be pressed is pressed according to the recommended pressing force, specifically including: When the press-fitting equipment is controlled to press-fit with the recommended press-fitting force as the target value, the actual press-fitting force applied to the battery stack to be press-fitted is monitored in real time by a pressure sensor. The actual pressing force is compared with the target value, and the output of the actuator is dynamically adjusted according to the comparison result to stabilize the actual pressing force within the allowable error range of the target value.

6. The method according to claim 5, characterized in that, The method further includes: During the pressing process, the compression displacement of the battery stack to be pressed is monitored in real time; Establish a real-time relationship curve between actual pressing force and compression displacement, and compare the real-time relationship curve with a pre-stored reference curve, wherein the reference curve reflects the correspondence between reference force and compression displacement; When the real-time relationship curve deviates from the reference curve, the pressing force is dynamically fine-tuned to make the actual curve follow the reference curve.

7. The method according to claim 1, characterized in that, The number of single batteries is greater than the preset number; And, pressing the battery stack to be pressed according to the recommended pressing force, specifically including: The pressing force is increased to the first pressure value at the first preset speed and pressure is maintained for the first time period; After the first period of pressure holding, the pressing force is increased to the recommended pressing force at a second preset speed and the second period of pressure holding is performed; wherein, the first pressure value is 50%-80% of the recommended pressing force, and the first preset speed is less than the second preset speed.

8. The method according to claim 1, characterized in that, During the pressing process of the battery stack to be pressed according to the recommended pressing force, the method further includes: Temperature data is acquired in real time by a temperature sensor, wherein the temperature data includes at least one of the ambient temperature and the temperature of the battery stack to be pressurized; When the monitored temperature data is lower than a first preset threshold, the pressing equipment is controlled to add a positive compensation force based on the recommended pressing force; or, When the temperature data is detected to be higher than the second preset threshold, the pressing equipment is controlled to reduce the negative compensation force based on the recommended pressing force.

9. The method according to claim 1, characterized in that, After pressing the battery stack to be pressed according to the recommended pressing force, the method further includes: maintaining the recommended pressing force for a preset holding time, controlling the actuator to depressurize to a preset maintenance pressure, and tightening the screws.

10. A fuel cell stack for a fuel cell system, characterized in that, The battery stack is obtained by press-fitting using the method described in any one of claims 1 to 9.

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