A fuel cell stack fastening device

Abstract

The application provides a fuel cell stack fastening device, and relates to the technical field of fuel cell systems, which comprises a front end plate and a rear end plate connected by a plurality of fastening pull rods, a fuel cell stack is arranged between the front end plate, the rear end plate and the fastening pull rods, the rear end plate is coated with an elastic sheet inside, and the middle part of the elastic sheet is convex in a certain curvature direction of the fuel cell stack. The application realizes the prevention of plastic deformation of the end plate of the fuel cell stack by the combination of different materials, so that the stacked bipolar plates and proton exchange membranes are subjected to uniform vertical plane force; the contact resistance of the fuel cell stack is further improved, the uneven distribution of the contact surface of the bipolar plate and the proton exchange membrane is changed, the local current density of the bipolar plate is reduced, the situation that the temperature of a certain point is too high is avoided, and the power generation efficiency of the fuel cell stack is improved.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell system technology, and specifically relates to a fuel cell stack fastening device. Background Technology

[0002] Fuel cell stacks are devices that convert chemical energy into electrical energy and are considered one of the most promising solutions to the energy crisis and environmental pollution. They are mainly composed of components such as bipolar plates (BP), proton exchange membranes (PEM), gas diffusion layers (GDL), and catalytic layers (CL). However, during fuel cell stack testing, it was found that poor contact between the bipolar plates and the proton exchange membrane leads to increased contact resistance, which is a significant reason for poor battery performance. Fuel cell bipolar plates are generally manufactured using stamping and etching methods. Due to material limitations, stamped bipolar plates often fail to meet design dimensional requirements. The upper platform of the metal plate's flow field is a smooth curved surface, resulting in a relatively small contact area between the bipolar plate and the proton exchange membrane. The fuel cell stack is secured with screws around its perimeter. Because the central area of ​​the end plates lacks constraint, significant deformation occurs, leading to plastic deformation of the end plates. This results in uneven stress distribution throughout the stack core, with higher stress around the perimeter and lower stress at the center. Consequently, the central flow field of the bipolar plate has less contact with the proton exchange membrane compared to the surrounding flow field, leading to increased contact resistance and poor fuel cell stack performance. While etched metal bipolar plates offer better flow field processing than stamped ones, they still cannot solve the problem of uneven stress distribution in the central area of ​​the fuel cell stack.

[0003] To address the aforementioned issues, existing designs incorporate a clamping adjustment mechanism into the rear end plate of the fuel cell stack. An adjusting bolt at the center of the end plate is used to adjust the elastic clamping components fixed to the rear end plate, aiming to improve the contact resistance inside the fuel cell stack. However, this design suffers from limitations because the disc springs have a small coverage area and cannot evenly balance the contact between the bipolar plates and the proton exchange membrane according to the stress conditions, thus limiting its effectiveness in improving the stack's contact resistance. Summary of the Invention

[0004] To address the technical problem of poor contact between the bipolar plates and the proton exchange membrane in existing fuel cell stack fastening devices, leading to increased contact resistance, this invention provides a fuel cell stack fastening device. This invention primarily utilizes the superimposed assembly of the opposing forces of spring steel to prevent plastic deformation of the end plates, ensuring that the bipolar plates and proton exchange membrane are subjected to uniform vertical plane forces, thereby reducing internal contact resistance.

[0005] The technical means employed in this invention are as follows:

[0006] A fuel cell stack fastening device includes a front end plate and a rear end plate connected by a plurality of fastening rods. A fuel cell stack is disposed between the front end plate, the rear end plate and the fastening rods. An elastic sheet is wrapped inside the rear end plate, and the middle part of the elastic sheet protrudes with a certain curvature towards the fuel cell stack.

[0007] Furthermore, the rear end plate and the elastic sheet covered by the rear end plate are provided with a plurality of threaded blind holes. The depth of the threaded blind holes does not exceed the position of the elastic sheet inside the rear end plate, and the threaded blind holes are threadedly connected to the set screw.

[0008] Furthermore, when the fastening rod applies a fastening force to the perimeter of the rear end plate, an outward force is generated in the center of the rear end plate. At this time, the elastic sheet generates a reaction force on the center of the rear end plate to counteract the force in the center of the rear end plate, so that the center of the rear end plate is balanced, thereby subjecting the bipolar plates and proton exchange membrane inside the fuel cell stack to uniform vertical plane forces.

[0009] Furthermore, the fastening rod is fixed to the outer surface of the front end plate and the rear end plate by fastening nuts.

[0010] Furthermore, the elastic sheet is made of spring steel, and the rear end plate is made of aluminum.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] This invention analyzes the fastening and sealing methods of fuel cell stacks, as well as the stress on components such as end plates, bipolar plates, and proton exchange membranes. The rear end plate utilizes cast aluminum-clad elastic sheets, with spring steel having a certain curvature and bulging towards the stack core. When the stack fastening rod applies force to the rear end plate, the force is transmitted to the elastic sheets inside the end plate, generating a superimposed counterforce to prevent plastic deformation of the rear end plate. This ensures that the bipolar plates and proton exchange membrane are subjected to uniform vertical plane forces, thereby increasing the contact area between the bipolar plates and proton exchange membrane, ensuring sufficient contact, and reducing contact resistance.

[0013] The present invention provides threaded holes and matching set screws on the rear end plate. By rotating the set screws, the set screws provide support to the elastic sheet inside the rear end plate, thereby balancing the stress on the rear end plate. As a result, the force is transmitted and ultimately acts on the center and surrounding area of ​​the bipolar plate flow field, further improving the contact resistance of the fuel cell stack. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0016] Figure 2 This is the front view of the present invention.

[0017] Figure 3 This is a side view of the present invention.

[0018] Figure 4 This is a top view of the present invention.

[0019] Figure 5 This is a cross-sectional view of the present invention.

[0020] Figure 6 This is an enlarged schematic diagram of the back-end board structure of the present invention.

[0021] In the diagram: 1. Fastening rod; 2. Front end plate; 3. Rear end plate; 4. Fuel cell stack; 5. Elastic sheet; 6. Set screw; 7. Fastening nut. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0026] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0027] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0028] like Figure 1-6 As shown, this invention provides a fuel cell stack fastening device, including a front end plate 2 and a rear end plate 3 connected by a plurality of fastening rods 1. The fastening rods 1 are fixed to the outer surfaces of the front end plate 2 and the rear end plate 3 by fastening nuts 7. A fuel cell stack 4 is disposed between the front end plate 2, the rear end plate 3 and the fastening rods 1. An elastic sheet 5 is wrapped inside the rear end plate 3, and the middle part of the elastic sheet 5 protrudes with a certain curvature towards the fuel cell stack 4. A plurality of threaded blind holes are formed on the rear end plate 3 and the elastic sheet 5 covered by the rear end plate 3. The depth of the threaded blind holes does not exceed the position of the elastic sheet 5 inside the rear end plate 3, and the threaded blind holes are threadedly connected to set screws 6.

[0029] When the fastening rod 1 applies a fastening force to the periphery of the rear end plate 3, an outward force is generated in the middle of the rear end plate 3. At this time, the elastic plate 5 generates a reaction force on the middle of the rear end plate 3 to counteract the force in the middle of the rear end plate 3, so that the middle of the rear end plate 3 is in force balance, thereby subjecting the bipolar plates and proton exchange membrane inside the fuel cell stack 4 to uniform vertical plane force.

[0030] The elastic sheet 5 is made of spring steel, and the rear end plate 3 is made of cast aluminum.

[0031] This application analyzes the fastening and sealing methods of the fuel cell stack 4, as well as the stress on components such as the end plates, bipolar plates, and proton exchange membranes. It determines that the rear end plate 3 uses cast aluminum-clad spring steel clips with a certain curvature, convex towards the stack core. When the fastening rod 1 is tightened, the rear end plate 3 experiences significant tensile force around its perimeter, while the central area, lacking this force, is prone to plastic deformation. When the stack fastening rod 1 applies force to the rear end plate 3, the force is transmitted to the spring steel inside the rear end plate 3, generating a superimposed counterforce to prevent plastic deformation of the rear end plate 3. This ensures that the bipolar plates and proton exchange membrane are subjected to uniform vertical plane forces. A certain depth of aluminum material is milled off the rear end plate 3 to reduce weight. Multiple threaded holes are machined at the ribs of the rear end plate 3 based on force analysis. The depth of the threaded holes does not exceed that of the spring steel. Rotation causes the set screw 6 to provide support to the spring steel clamps inside the rear end plate 3. By controlling the number of turns of the set screw 6 at different positions on the rear end plate 3, the deformation of the spring steel clamps is controlled, altering the stress conditions inside the fuel cell stack 4 and thus improving the contact resistance of the fuel cell stack 4. This also corrects the uneven distribution of the contact surface between the bipolar plates and the proton exchange membrane, reducing excessive local current density in the bipolar plates, which could lead to overheating at certain points and improving the power generation efficiency of the fuel cell stack.

[0032] Finally, 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell stack fastening device, characterized in that: It includes a front plate (2) and a rear plate (3) connected by several fastening rods (1). A fuel cell stack (4) is provided between the front plate (2), the rear plate (3) and the fastening rods (1). An elastic sheet (5) is wrapped inside the rear plate (3). The middle part of the elastic sheet (5) protrudes with a certain curvature towards the fuel cell stack (4). The rear end plate (3) and the elastic sheet (5) covered by the rear end plate (3) have a number of threaded blind holes. The depth of the threaded blind holes does not exceed the position of the elastic sheet (5) inside the rear end plate (3). The threaded blind holes are threadedly connected to the set screw (6).

2. The fuel cell stack fastening device according to claim 1, characterized in that, When the fastening rod (1) applies a fastening force to the periphery of the rear end plate (3), an outward force is generated in the middle of the rear end plate (3). At this time, the elastic sheet (5) generates a reaction force on the middle of the rear end plate (3) to counteract the force in the middle of the rear end plate (3), so that the middle of the rear end plate (3) is in force balance, thereby subjecting the bipolar plates and proton exchange membrane inside the fuel cell stack (4) to uniform vertical plane force.

3. The fuel cell stack fastening device according to claim 1, characterized in that, The fastening rod (1) is fixed to the outer surface of the front end plate (2) and the rear end plate (3) by fastening nuts (7).

4. The fuel cell stack fastening device according to claim 1, characterized in that, The elastic sheet (5) is made of spring steel, and the rear end plate (3) is made of aluminum.

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