Axial Force Prediction Method for Wave Springs of Fuel Cell Suspension Support Devices

Abstract

The present invention discloses a method for predicting the axial force of a wave spring for a fuel cell suspension support device, comprising the following steps: establishing a three-dimensional model of the wave spring; fixing one end of the wave spring and subjecting the other end of the wave spring to cyclic compression; calculating the axial force of the wave spring under cyclic compression according to the motion law of the cyclic compression; the present invention can predict the axial force of the spring when the structural parameters and axial deformation amount of the wave spring are known, providing a basis for the suspension support assembly design of a fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell stack assembly design, in particular to a method for predicting the axial force of a wave spring for a fuel cell suspension support device. Background Art

[0002] Due to the advantages of energy conservation, environmental protection and high efficiency, fuel cells have great application prospects in commercial vehicles and construction machinery in the future.

[0003] However, due to the reason of bolt assembly design, there is inevitably non-linear force-electric contact coupling between the bipolar plates of the fuel cell, resulting in uneven distribution of the contact force on the bipolar plates. Under the vehicle vibration condition, the uneven distribution of the contact force is likely to cause a large current between the bipolar plates, causing the metal bipolar plate to be perforated and inducing the explosion of the fuel cell stack. The current technology for equalizing the contact force of the bipolar plate is mainly the pneumatic end plate suspension support device. However, since it requires the use of parts such as a compressor, a high-pressure airbag and a control system, its reliability is lower and the cost is higher. Using a wave spring can also make the contact force on the bipolar plate reach a uniform distribution effect, and there is no need to use parts such as a compressor and an airbag, so the failure rate is lower and the performance is more reliable. However, at present, there is no quantitative research on the axial force of the wave spring for the fuel cell suspension support device under cyclic compression deformation, and it is impossible to provide a basis for designers to predict the axial force of the wave spring. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and the title of the specification of this application, to avoid obscuring the purpose of this part, the abstract and the title of the specification. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the above and / or existing problems in predicting the axial force of the wave spring under cyclic compression in the fuel cell stack suspension support device, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is that the axial force of the wave spring under cyclic compression cannot be predicted in the prior art. The present invention accurately and quantitatively predicts the equivalent Young's modulus of the fuel cell stack to reflect the equivalent assembly stiffness of the fuel cell stack.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: A method for predicting the axial force of a wave spring for a fuel cell suspension support device, comprising the following steps,

[0008] Establish a three-dimensional model of the wave spring;

[0009] Fix one end of the wave spring and perform cyclic compression on the other end of the wave spring;

[0010] Calculate the axial force of the corrugated spring under cyclic compression according to the motion law of cyclic compression.

[0011] As a preferred solution of the method for predicting the axial force of the corrugated spring used in the fuel cell suspension support device of the present invention, wherein: before cyclic compression of the corrugated spring, first establish the three-dimensional models of the upper pressure plate and the lower pressure plate, and then establish the three-dimensional model of the assembled corrugated spring, lower pressure plate and upper pressure plate. The corrugated spring is placed between the upper pressure plate and the lower pressure plate, and the lower pressure plate is fixed.

[0012] As a preferred solution of the method for predicting the axial force of the corrugated spring used in the fuel cell suspension support device of the present invention, wherein: the upper pressure plate cyclically compresses according to the motion law of the sine function. The expression of the motion law of the sine function is as follows.

[0013] x = 2.5sin[4π(t + 0.125)] - 2.5;

[0014] Among them, the cyclic compression motion frequency f = 2Hz, the peak value A = 2.5mm, x is the axial displacement of the upper pressure plate, and t is the cyclic motion time.

[0015] As a preferred solution of the method for predicting the axial force of the corrugated spring used in the fuel cell suspension support device of the present invention, wherein: when loading the upper pressure plate, the calculation formula for the axial force of the corrugated spring in the loading stage is

[0016]

[0017] Among them, D1 is the outer diameter of the corrugated spring, D2 is the inner diameter of the corrugated spring, n is the number of layers of the corrugated spring, d is the layer thickness of the corrugated spring, w is the number of corrugations of the corrugated spring, and E is the Young's modulus of the spring material.

[0018] As a preferred solution of the method for predicting the axial force of the corrugated spring used in the fuel cell suspension support device of the present invention, wherein: when releasing the upper pressure plate and the upper pressure plate unloads, the calculation formula for the axial force of the corrugated spring in the unloading stage is

[0019]

[0020] The beneficial effect of the present invention is that it can predict the axial force of the spring when the structural parameters and axial deformation of the corrugated spring are known, providing a basis for the suspension support assembly design of the fuel cell stack. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is the plan view of the wave spring suspension support of the fuel cell stack in the present invention.

[0023] Figure 2 It is the structural diagram of the wave spring in the present invention.

[0024] Figure 3 It is the model diagram of the wave spring placed between the upper pressure plate and the lower pressure plate for axial cyclic compression in the present invention.

[0025] Figure 4 It is the axial force hysteresis loop diagram of the wave spring in the present invention when D1 = 60mm, D2 = 51mm, d = 0.7mm, n = 9, w = 4, and the compression amount x changes according to the sine function law.

[0026] Figure 5 It is the comparison diagram of the predicted axial force and the simulation result of the wave spring in the present invention when D1 = 60mm, D2 = 51mm, d = 0.7mm, n = 9, x = 4, and the number of corrugations w is 4, 5, 6 respectively under the loading condition.

[0027] Figure 6 It is the comparison diagram of the predicted axial force and the simulation result of the wave spring in the present invention when D1 = 60mm, D2 = 51mm, d = 0.7mm, w = 4, x = 4, and the number of layers n is 1 - 9 under the loading condition.

[0028] Figure 7 It is the comparison diagram of the predicted axial force and the simulation result of the wave spring in the present invention when D1 = 60mm, D2 = 51mm, n = 9, w = 4, x = 4, and the layer thickness d is 0.1 - 0.9mm under the loading condition.

[0029] Figure 8 It is the comparison diagram of the predicted axial force and the simulation result of the wave spring in the present invention when D1 = 60mm, d = 0.7mm, n = 9, w = 4, x = 4, and the inner diameter D2 is 45 - 51mm under the loading condition.

[0030] Figure 9 It is the comparison diagram of the predicted axial force and the simulation result of the wave spring in the present invention when D2 = 51mm, d = 0.7mm, n = 9, w = 4, x = 4, and the outer diameter D1 is 60 - 65mm under the loading condition.

[0031] Figure 10It is a comparison diagram of the predicted axial force and the simulation result when D1 = 60mm, D2 = 51mm, d = 0.7mm, n = 9, x = 4, and the number of corrugations w is 4, 5, 6 respectively for the wave spring of the present invention under the unloading condition.

[0032] Figure 11 It is a comparison diagram of the predicted axial force and the simulation result when D1 = 60mm, D2 = 51mm, d = 0.7mm, w = 4, x = 4, and the number of layers n is from 1 to 9 for the wave spring of the present invention under the unloading condition.

[0033] Figure 12 It is a comparison diagram of the predicted axial force and the simulation result when D1 = 60mm, D2 = 51mm, n = 9, w = 4, x = 4, and the layer thickness d is from 0.1 to 0.9mm for the wave spring of the present invention under the unloading condition.

[0034] Figure 13 It is a comparison diagram of the predicted axial force and the simulation result when D1 = 60mm, d = 0.7mm, n = 9, w = 4, x = 4, and the inner diameter D2 is from 45 to 51mm for the wave spring of the present invention under the unloading condition.

[0035] Figure 14 It is a comparison diagram of the predicted axial force and the simulation result when D2 = 51mm, d = 0.7mm, n = 9, w = 4, x = 4, and the outer diameter D1 is from 60 to 65mm for the wave spring of the present invention under the unloading condition.

[0036] Among them, 1 is a stainless - steel end plate, 2 is an aluminum - alloy end plate, 3 is a wave spring, 4 is a bipolar plate, 5 is a copper electrode, 6 is a lower pressing plate, and 7 is an upper pressing plate. Detailed implementation manners

[0037] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following will make a detailed description of the specific implementation manners of the present invention with reference to the accompanying drawings of the specification.

[0038] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0039] Secondly, the so - called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0040] Embodiment 1

[0041] Reference Figures 1 - 3 This is the first embodiment of the present invention, which provides a method for predicting the axial force of a corrugated spring for a fuel cell suspension support device, and includes the following steps:

[0042] S1. Establish a corrugated spring model;

[0043] S2. Establish a 3D model of the upper pressure plate 7 and the lower pressure plate 6;

[0044] S3. Establish a 3D model in which the corrugated spring 3, the lower pressure plate 6 and the upper pressure plate 7 are assembled together. The corrugated spring 3 is placed between the upper pressure plate 7 and the lower pressure plate 6, and the lower pressure plate 6 is fixed;

[0045] S4. Cyclically compress the upper pressure plate 7 according to the sine function motion law. The sine function motion law is as follows:

[0046] x = 2.5sin[4π(t + 0.125)] - 2.5;

[0047] Among them, the cyclic compression motion frequency f = 2Hz, the peak value A = 2.5mm, x is the axial displacement of the upper pressure plate 7, and t is the cyclic motion time;

[0048] S5. Calculate the axial force of the corrugated spring 3 in the loading stage and the unloading stage. When loading by pressing down the upper pressure plate 7, the calculation formula for the axial force F of the corrugated spring 3 is

[0049]

[0050] When releasing the upper pressure plate 7 for unloading, the calculation formula for the axial force F of the corrugated spring 3 is

[0051]

[0052] Among them, D1 is the outer diameter of the corrugated spring 3, D2 is the inner diameter of the corrugated spring 3, n is the number of layers of the corrugated spring 3, d is the layer thickness of the corrugated spring 3, w is the number of corrugations of the corrugated spring 3, and E is the Young's modulus of the spring material.

[0053] The structure of the fuel cell stack is as Figure 1As shown in the figure, it includes a suspension support device, a bipolar plate, and a copper electrode. The suspension support device includes a stainless steel end plate 1 and an aluminum alloy end plate 2. A number of corrugated springs 3 are arranged between the stainless steel end plate 1 and the aluminum alloy end plate 2. A circular groove slightly larger in diameter than the corrugated spring 3 is opened on the aluminum alloy end plate 2, and the corrugated spring 3 is fixedly placed in the groove to prevent sliding. One end of the stainless steel end plate 1 away from the corrugated spring 3 is connected to a bipolar plate 4, which is the skeleton and foundation of the fuel cell. One end of the bipolar plate 4 away from the stainless steel end plate 1 is connected to a copper electrode 5, which has good electrical conductivity and heat dissipation. When simulating the cyclic loading-unloading condition of the fuel cell suspension support device, the stainless steel end plate 1 of the stack is simplified to an upper pressing plate 7, and the aluminum alloy end plate 2 is simplified to a lower pressing plate 6, and the corrugated spring 3 is placed between the upper pressing plate 7 and the lower pressing plate 6 (as Figure 3 shown).

[0054] The present invention combines the performance of the corrugated spring 3 under cyclic vibration conditions and considers the influence of the spring outer diameter on the axial force of the spring, and is applicable to the prediction of the axial force of multiple layers of corrugated springs 3 under cyclic loading conditions; it can calculate the clamping force received by the end plate of the fuel cell stack suspension support device when the specifications of different corrugated springs 3 are known, providing a basis for the assembly design of the fuel cell stack.

[0055] Embodiment 2

[0056] Referring to Figure 4 、 5 and Figure 10 , this is the second embodiment of the present invention. This embodiment is based on Embodiment 1, and this embodiment uses scientific verification means to verify that the calculation method in Embodiment 1 can achieve the prediction of the axial force of the corrugated spring under cyclic conditions.

[0057] In this embodiment, a finite element simulation analysis software is used to perform cyclic simulation on the corrugated spring stack, and the data obtained after the simulation is compared with the data calculated using the mathematical model in the present invention.

[0058] For the corrugated spring with D1 = 60mm, D2 = 51mm, d = 0.7mm, n = 9, and x = 4mm, while keeping other structural parameters of the corrugated spring 3 unchanged, in this embodiment, the axial forces calculated at w = 4, 5, and 6 corrugation numbers under cyclic conditions are compared with the simulation results.

[0059] The axial compression deformation x = 4mm, and the Young's modulus E of the corrugated spring material is 203395MPa.

[0060] The calculation steps are as follows,

[0061] (1) When the corrugation number w = 4, the theoretical value of the spring axial force is calculated as,

[0062] Loading stage:

[0063]

[0064] Unloading stage:

[0065]

[0066] (2) When the number of corrugations w = 5, the theoretical value of the axial force of the spring is calculated as,

[0067] Loading stage:

[0068]

[0069] Unloading stage:

[0070]

[0071] (3) When the number of corrugations w = 6, the theoretical value of the axial force of the spring is calculated as,

[0072] Loading stage:

[0073]

[0074] Unloading stage:

[0075]

[0076] The simulation values and the calculated theoretical values of the present invention are as Figure 5 and Figure 10 shown, Figure 5 is the loading stage, Figure 10 is the unloading stage, and the scatter plot represents the percentage error. The overall error between the simulation values and the theoretical values of the calculated results remains below 30%, and even lower, within the reasonable range of engineering errors.

[0077] Example 3

[0078] Referring to Figure 4 、 6 and Figure 11 , this is the third embodiment of the present invention. Based on Embodiment 1 and Embodiment 2, this embodiment verifies by means of scientific verification that the calculation method in Embodiment 1 can achieve the prediction of the axial force of the corrugated spring under cyclic conditions.

[0079] For the corrugated spring, D1 = 60mm, D2 = 51mm, d = 0.7mm, w = 4, x = 4mm. Keeping other structural parameters of the corrugated spring 3 unchanged, in this embodiment, when the number of layers n = 1, 3, 5, 7, 9, the axial forces calculated under cyclic conditions are compared with the simulation results.

[0080] The axial compression deformation x = 4mm, and the Young's modulus E of the corrugated spring material is 203395 Mpa.

[0081] The calculation steps are as follows:

[0082] (1) When the number of layers n = 1, the theoretical value of the spring axial force is calculated as follows for the loading stage:

[0083]

[0084] For the unloading stage:

[0085]

[0086] (2) When the number of layers n = 3, the theoretical value of the spring axial force is calculated as follows for the loading stage:

[0087]

[0088] For the unloading stage:

[0089]

[0090] (3) When the number of layers n = 5, the theoretical value of the spring axial force is calculated as follows for the loading stage:

[0091]

[0092] For the unloading stage:

[0093]

[0094] (4) When the number of layers n = 7, the theoretical value of the spring axial force is calculated as follows for the loading stage:

[0095]

[0096] For the unloading stage:

[0097]

[0098] (5) When the number of layers n = 9, the theoretical value of the spring axial force is calculated as follows for the loading stage:

[0099]

[0100] For the unloading stage:

[0101]

[0102] The simulation values and the calculated theoretical values of the present invention are as Figure 6 and Figure 11 shown, Figure 6 for the loading stage, Figure 11This is the unloading stage, and the scatter plot represents the percentage error. The overall error between the simulation value and the theoretical value of the calculation result remains below 30%, or even lower, within the reasonable range of engineering error.

[0103] Example 4

[0104] Refer to Figure 4 、 7 and Figure 12 , which is the fourth embodiment of the present invention. This embodiment is based on Embodiment 1 and Embodiment 2, and uses scientific verification means to verify that the calculation method in Embodiment 1 can achieve the prediction of the axial force of the wave spring under cyclic conditions.

[0105] For the wave spring with D1 = 60mm, D2 = 51mm, n = 9, w = 4, x = 4mm, while keeping other structural parameters of the wave spring 3 unchanged, in this embodiment, when the layer thickness d = 0.1, 0.3, 0.5, 0.7, 0.9mm, the axial force calculated under cyclic conditions is compared with the simulation results.

[0106] The axial compression deformation x = 4mm, and the Young's modulus E of the wave spring material is 203395MPa.

[0107] The calculation steps are as follows.

[0108] (1) When the layer thickness d = 0.1mm, the theoretical value of the spring axial force is calculated as follows.

[0109] Loading stage:

[0110]

[0111] Unloading stage:

[0112]

[0113] (2) When the layer thickness d = 0.3mm, the theoretical value of the spring axial force is calculated as follows.

[0114] Loading stage:

[0115]

[0116] Unloading stage:

[0117]

[0118] (3) When the layer thickness d = 0.5mm, the theoretical value of the spring axial force is calculated as follows.

[0119] Loading stage:

[0120]

[0121] Unloading stage:

[0122]

[0123] (4) When the layer thickness d = 0.7 mm, the theoretical value of the spring axial force is calculated as

[0124] Loading stage:

[0125]

[0126] Unloading stage:

[0127]

[0128] (5) When the layer thickness d = 0.9 mm, the theoretical value of the spring axial force is calculated as

[0129] Loading stage:

[0130]

[0131] Unloading stage:

[0132]

[0133] The simulation values and the calculated theoretical values of the present invention are as Figure 7 and Figure 12 shown. Figure 7 For the loading stage, Figure 12 For the unloading stage, the scatter plot represents the error percentage. In the loading and unloading stages, as Figure 7 and Figure 12 show, for the wave spring with a layer thickness d = 0.1 mm, due to the relatively thin layer thickness of the spring and the large influence of the spring layer gap, the error between the simulation value and the theoretical value reaches 50%. For the wave springs with other layer thicknesses, the error between the simulation value and the calculated theoretical value generally remains below 30%, or even lower, with good fitting, within the reasonable range of engineering error.

[0134] Example 5

[0135] Referring to Figure 4 , 8 and Figure 13 , this is the fifth example of the present invention. This example is based on Example 1 and Example 2, and this example verifies by scientific verification means that using the method in the present application can achieve the prediction of the spring axial force under cyclic working conditions.

[0136] For the wave spring with D1 = 60 mm, D2 = 51 mm, n = 9, w = 4, x = 4 mm, while keeping other structural parameters of the wave spring 3 unchanged, in this example, when the inner diameter D2 = 45, 47, 49, 51 mm, the axial forces calculated under cyclic working conditions are compared with the simulation results.

[0137] The axial compression deformation x = 4 mm, and the Young's modulus E of the wave spring material is 203395 MPa.

[0138] The calculation steps are as follows.

[0139] (1) When the inner diameter D2 = 45 mm, the theoretical value of the spring axial force is calculated as

[0140] Loading stage:

[0141]

[0142] Unloading stage:

[0143]

[0144] (2) When the inner diameter D2 = 47 mm, the theoretical value of the spring axial force is calculated as

[0145] Loading stage:

[0146]

[0147] Unloading stage:

[0148]

[0149] (3) When the inner diameter D2 = 49 mm, the theoretical value of the spring axial force is calculated as

[0150] Loading stage:

[0151]

[0152] Unloading stage:

[0153]

[0154] (4) When the inner diameter D2 = 51 mm, the theoretical value of the spring axial force is calculated as

[0155] Loading stage:

[0156]

[0157] Unloading stage:

[0158]

[0159] The simulation values and the calculated theoretical values of the present invention are as Figure 8 and Figure 13 shown. Figure 8 For the loading stage, Figure 13For the unloading stage, the scatter plot represents the percentage error. During cyclic loading, the error between the simulated value and the theoretical value of the calculated result is generally maintained below 15%, with good fitting and within a reasonable range of engineering error.

[0160] Example 6

[0161] Refer to Figure 4 、 9 and Figure 14 , which is the sixth example of the present invention. This example is based on Example 1 and Example 2, and uses scientific verification methods to verify that the method in this application can achieve the prediction of the axial force of the spring under cyclic conditions.

[0162] For the wave spring, D2 = 51 mm, d = 0.7 mm, n = 9, w = 4, x = 4 mm. Keeping other structural parameters of the wave spring 3 unchanged, in this example, when the outer diameter D1 = 60, 62, 64 mm, the spring force calculated under cyclic conditions is compared with the simulation results.

[0163] The axial compression deformation x = 4 mm, and the Young's modulus E of the wave spring material is 203395 MPa.

[0164] The calculation steps are as follows.

[0165] (1) When the outer diameter D1 = 60 mm, the theoretical value of the spring axial force is calculated as

[0166] Loading stage:

[0167]

[0168] Unloading stage:

[0169]

[0170] (2) When the outer diameter D1 = 62 mm, the theoretical value of the spring axial force is calculated as

[0171] Loading stage:

[0172]

[0173] Unloading stage:

[0174]

[0175] (3) When the outer diameter D1 = 64 mm, the theoretical value of the spring axial force is calculated as

[0176] Loading stage:

[0177]

[0178] Unloading stage:

[0179]

[0180] The simulation values and the theoretical values calculated by the present invention are as Figure 9 and Figure 14 shown Figure 9 is the loading stage Figure 14 is the unloading stage, and the scatter plot represents the percentage error. In the cyclic loading, the error between the simulation value and the theoretical value of the calculation result is generally maintained below 15%, with good fitting, within the reasonable range of engineering error.

[0181] It can be seen from Examples 2-6 that by using the prediction method of the present invention, the axial force F of the wave spring under the cyclic loading-unloading condition can be accurately predicted.

[0182] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for predicting the axial force of a wave spring used in a fuel cell suspension support device, characterized in that: Including the following steps, Establish a three-dimensional model of the wave spring, with the Young's modulus E of the wave spring material being 203395 MPa; One end of the wave spring is fixed, and the other end of the wave spring is cyclically compressed; According to the motion law of cyclic compression, calculate the axial force of the wave spring under cyclic vibration conditions. Specifically, when the upper pressure plate is pressed down for loading, the calculation formula for the axial force F of the wave spring in the loading stage is, ； Among them, D 1 is the outer diameter of the wave spring, D 2 is the inner diameter of the wave spring, n is the number of layers of the wave spring, d is the layer thickness of the wave spring, w is the number of corrugations of the wave spring, E is the Young's modulus of the spring material; When the upper pressure plate is released and unloaded, the calculation formula for the axial force F of the wave spring in the unloading stage is, 。 2. The waveform spring axial force prediction method for a fuel cell suspension support device according to claim 1, characterized in that: Before cyclically compressing the wave spring, first establish three-dimensional models of the upper pressure plate and the lower pressure plate, and then establish a three-dimensional model of the wave spring, the lower pressure plate, and the upper pressure plate assembled together. The wave spring is placed between the upper pressure plate and the lower pressure plate, and the lower pressure plate is fixed.

3. The waveform spring axial force prediction method for the fuel cell suspension support device according to claim 2, characterized in that: The upper pressure plate cyclically compresses according to the sine function motion law, and the expression of the sine function motion law is as follows, ； Among them, the cyclic compression motion frequency f = 2 Hz, the peak value A = 2.5 mm, x is the axial displacement of the upper pressure plate, and t is the cyclic motion time.

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