PLATE STRUCTURE FOR A FUEL CELL

Abstract

Plate assembly (20) for a fuel cell, the plate assembly (20) comprising: a first plate (30) with a planar section (34) that defines a reference plane (36); a raised bead seal (26) that protrudes from the reference plane (36) and extends along a center line (42) on the reference plane (36); a tunnel (28) projecting away from the reference plane (36) and extending along a path (44) on the reference plane (36), the tunnel (28) intersecting the raised bead seal (26); where the path (44) and the center line (42) intersect and form a first intersection angle (50) on the reference plane (36); where the first intersection angle (50) is not a right angle; where the path (44) of the tunnel (28) is linear; wherein the center line (42) of the raised bead seal (26) includes linear sections and nonlinear sections; wherein the first angle of intersection (50) between the path (44) and a tangent (58) of the center line (42) is measured at the intersection of the center line (42) and the path (44); wherein the intersection of the path (44) and the center line (42) forms a second angle of intersection (52) in the reference plane (36); where the first angle of intersection (50) and the second angle of intersection (52) are complementary angles; where the first angle of intersection (50) and the second angle of intersection (52) are adjacent angles; and where one of the angles of intersection (50) and the second angle of intersection (52) is an obtuse angle and the other of the angles of intersection (50) and the second angle of intersection (52) is an acute angle; characterized by the fact that the acute angle is less than forty-five degrees.

Description

INTRODUCTION

[0001] The present invention relates to a plate assembly for a fuel cell. The disclosure relates generally to a plate assembly with a raised bead seal for sealing against an adjacent plate.

[0002] For example, German patent application DE 10 2017 125 552 A1 describes a plate structure for a fuel cell according to the preamble of claim 1. German patent applications DE 10 2007 048 184 B3, DE 10 2017 122 905 A1, DE 10 2017 124 855 A1, DE 10 2017 124 498 A1 and DE 10 2017 127 342 A1 show related structures.

[0003] Fuel cells are electrochemical devices that combine a fuel, such as hydrogen, and an oxidizer, such as oxygen, to generate electricity. The term "fuel cell" is typically used to refer to either a single cell or a multitude of cells, depending on the context. A multitude of individual cells are typically bundled together to form a stack, with the multitude of cells usually arranged in electrical series.

[0004] Various fuel cell types can be provided, such as phosphoric acid, alkaline, molten carbonate, solid oxide, and proton exchange membrane (PEM). The basic components of a PEM fuel cell are two electrodes separated by a polymer membrane electrolyte. Each electrode is coated on one side with a thin layer of catalyst. The electrodes, the catalyst, and the membrane together form a membrane electrode assembly (MEA).

[0005] In a typical PEM fuel cell, the MEA is positioned between anode and cathode diffusion media (hereinafter referred to as "DMs") or diffusion layers formed from a compliant, conductive, and gas-permeable material, such as carbon fabric or paper. The DMs serve as primary current collectors for the anode and cathode and provide mechanical support for the MEA. The DMs and MEA are pressed between an electronically conductive plate pair, such as a monopolar plate or a bipolar plate, which acts as a secondary current collector to gather current from the primary current collectors.

[0006] Monopolar plates typically consist of a single thin sheet, while bipolar plates usually consist of two thin sheets facing each other. The sheets define a flow path on one outer surface to convey fuel to the anode of the MEA or to deliver oxidizer to the cathode side of the MEA. In a bipolar plate, an outer surface on the other sheet defines a flow path to convey fuel to the anode of the MEA or to deliver oxidizer to the cathode side of the MEA. If the sheets are joined together in the case of bipolar plates, the joined surfaces can define a flow path for a dielectric cooling fluid. The plates are typically made of a malleable metal that provides suitable strength, electrical conductivity, and corrosion resistance.

[0007] To reduce unwanted fluid leakage between the plates, a gasket is often used. The gasket is arranged along a circumferential edge of the plates and / or around the circumference of an opening through the plates. The gasket may be an elastomeric seal, or alternatively, the metal plates may be formed to create a raised bead gasket. The raised bead gasket may be formed on a flat metal sheet adjacent to an outer edge of the sheet or adjacent to an edge surrounding an opening formed in the sheet. The raised bead gasket may be formed in the metal sheet by a stamping operation, although other methods may be used. The raised bead gasket may be substantially symmetrical about a longitudinal centerline of the raised bead. However, it should be noted that the raised bead gasket may not be symmetrical about the longitudinal centerline.The raised bead seal can have a generally arcuate cross-sectional shape perpendicular to the longitudinal centerline. This generally arcuate cross-sectional shape results in an elastic response to a load in a direction normal to the flat metal sheet.

[0008] The raised bead seal is compressed against an adjacent plate to form a seal. If some sections of the raised bead seal have high stiffness and others have lower stiffness, the areas of high stiffness can prevent the lower stiffness areas from forming a tight seal. Therefore, raised bead seals should have uniform stiffness throughout to form a tight seal around the entire perimeter of the plates and / or the entire perimeter of the adjacent opening. SUMMARY

[0009] A plate assembly for a fuel cell is provided. The plate assembly includes a first plate with a flat section that defines a reference plane. A raised bead gasket projects from the reference plane and extends along a centerline on the reference plane. A tunnel projects from the reference plane and extends along a path on the reference plane. This tunnel intersects the raised bead gasket. The path and the centerline intersect, forming a first intersection angle on the reference plane. The first intersection angle is not a right angle. The path and centerline are arranged to form a specific value of the first intersection angle to control the stiffness of the raised bead gasket.

[0010] The path of the tunnel is linear. In another, non-independently stressed aspect of the plate structure, the centerline of the raised bead seal may be non-linear.

[0011] The first angle of intersection is measured between the path and a tangent to the centerline at the point of intersection of the centerline and the path.

[0012] The intersection of the path and the centerline forms a second angle of intersection in the reference plane. The first and second angles of intersection are complementary angles. The first and second angles of intersection are adjacent angles.

[0013] One of the angles of intersection, formed by the first and second angles, is an obtuse angle, and the other is an acute angle. The acute angle is less than seventy-five degrees.

[0014] In one aspect of the plate structure, the increased bead seal exhibits a stiffness that increases with a decrease in the value of the acute angle and decreases with an increase in the value of the acute angle.

[0015] In another aspect of the plate structure, the first plate defines an edge and a connection through the first plate, wherein the tunnel is in fluid communication with the edge of the first plate on a first side of the raised bead seal and in fluid communication with the connection on a second side of the raised bead seal.

[0016] In another aspect of the plate setup, the plate setup includes a second plate with a flat section on the reference plane opposite the first flat section of the first plate. The second plate is attached to the first plate and is a mirror image of the first plate, with the first and second plates forming a bipolar plate.

[0017] A bipolar plate assembly for a fuel cell is also provided. The bipolar plate assembly comprises a first plate with a flat section defining a reference plane, and a second plate with a flat section on the reference plane opposite the first flat section of the first plate. A raised bead seal is formed in the first plate and projects from the reference plane. The raised bead seal extends along a centerline on the reference plane. A tunnel is formed in the first plate and projects from the reference plane. This tunnel extends along a path on the reference plane. The tunnel intersects the raised bead seal. The path and the centerline intersect, forming a first angle of intersection and an adjacent second angle of intersection on the reference plane. The first and second angles of intersection form complementary angles.The first angle of intersection is an acute angle and the second angle of intersection is an obtuse angle.

[0018] In one aspect of the bipolar plate setup, the path of the tunnel is linear. In another aspect of the bipolar plate setup, the centerline of the raised bead seal is nonlinear. In yet another aspect of the bipolar plate setup, the first intersection angle between the path and a tangent to the centerline is measured at the intersection of the centerline and the path.

[0019] In another aspect of the bipolar plate design, the acute angle is less than seventy-five degrees. In yet another aspect of the bipolar plate design, the raised bead gasket exhibits stiffness. The stiffness of the raised bead gasket increases with a decrease in the value of the acute angle. The stiffness of the raised bead gasket decreases with an increase in the value of the acute angle.

[0020] In another aspect of the bipolar plate setup, the first plate and the second plate are mirror images of each other across the reference plane.

[0021] A method for manufacturing a plate assembly for a fuel cell is also provided. The method involves forming a first plate to enclose a raised bead seal. The raised bead seal projects from a reference plane and extends along a centerline on the reference plane. The raised bead seal exhibits stiffness. The first plate is shaped to include a tunnel that projects from the reference plane and extends along a path on the reference plane. The tunnel intersects the raised bead seal. The path and the centerline intersect, forming a first angle of intersection and an adjacent second angle of intersection on the reference plane. The first and second angles of intersection are complementary angles. The first angle of intersection is an acute angle, and the second angle of intersection is an obtuse angle.The relative orientation between the tunnel path and the centerline of the raised bead seal is controlled to adjust the values ​​of the first and second cutting angles. These values ​​are controlled to influence the stiffness of the raised bead seal, such that the stiffness increases with a decrease in the acute angle and decreases with an increase in the acute angle.

[0022] Accordingly, the relative angle between the raised bead seal and the tunnel is controlled to regulate the stiffness of the raised bead seal. In this way, the stiffness of the raised bead seal can be adjusted to be uniform throughout all sections, thus ensuring a tight seal across all sections.

[0023] The foregoing features and advantages, as well as further features and advantages of the present gauges, can easily be derived from the following detailed description of the best ways of carrying out the gauges when considered in conjunction with the associated drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic top view of a plate structure for a fuel cell stack. Fig. Figure 2 is a schematic, fragmentary top view of the plate structure, showing a tunnel and a raised bead seal adjacent to an opening in the plate structure. Fig. Figure 3 is a schematic fragmentary cross-sectional view of two of the plate assemblies that form a bipolar plate assembly. DETAILED DESCRIPTION

[0024] Experts in the field will recognize that terms such as "above," "below," "upwards," "downwards," "above," "below," etc., are used descriptively for the figures and do not constitute limitations on the scope of the disclosure defined by the appended claims. Furthermore, the teachings herein may be described in relation to the functional or logical block components or various processing steps. It should be noted that such block components may be composed of any number of hardware, software, and / or firmware components configured to perform the specified functions.

[0025] With regard to FIG. 20, in which the same reference numerals denote the same parts for the different views, a plate assembly is generally shown. The plate assembly 20 is configured for use in a fuel cell or fuel cell stack, as is known in the art. For example, the plate assembly 20 can be configured as a monopolar plate, or two plate assemblies 20 can be combined and configured as a bipolar plate, as shown in FIG. 20. Fig. 3 shown. The special features of the fuel cell are not relevant to the teachings of this revelation and are therefore not described in detail here.

[0026] With reference to Fig. 1. The plate assembly 20 includes an outer circumferential edge 22 and defines a plurality of openings 24 extending through the plate assembly 20. A raised bead seal 26 is arranged adjacent to the perimeter of at least one of the openings 24. An additional raised bead seal 26 is also arranged adjacent to the outer circumferential edge 22 of the plate assembly 20. A tunnel 28 extends from the periphery of the opening 24 across the raised bead seal 26. The Fig. The intersection point shown in section 1 between the raised bead seal 26 and the tunnel 28 is described below with reference to the Fig. 2 and Fig. 3 described in more detail.

[0027] The plate assembly 20 includes at least one plate. If the plate assembly 20 is configured as a monopolar plate assembly 20, the plate assembly 20 includes only a first plate 30. If the plate assembly 20 is configured as a bipolar plate assembly 60, as in Fig. As shown in 3, the plate structure 20 includes the first plate 30 and a second plate 32.

[0028] With reference to Fig. In section 3, the first plate 30 includes a planar section 34 that defines a reference plane 36. The reference plane 36 can, for example, be an outer surface of the planar section 34. With reference to Fig. 2 and, as mentioned above, the first plate 30 defines an opening 24 extending through the first plate 30. The first plate 30 forms the rim 38 of the opening 24. The first plate 30 further includes a port 40 extending through the first plate 30. The opening 24 and the port 40 can be arranged in fluid communication with other components of the fuel cell, as is known in the art.

[0029] The raised bead seal 26 is laterally spaced from the edge 38 of the opening 24 and generally extends around the opening 24. The raised bead seal 26 projects from the reference plane 36 and extends along a centerline 42 located on the reference plane 36. The centerline 42 forms an endless loop around the opening 24. The raised bead seal 26 can be formed on the first plate 30 and / or the second plate 32. The raised bead seal 26 can be formed in the metal sheet by a punching operation, although other methods may also be used. The raised bead seal 26 can be substantially symmetrical about a longitudinal centerline 42. However, it should be noted that the raised bead seal 26 does not have to be symmetrical about the longitudinal centerline 42. The raised bead seal 26 can have a generally arcuate cross-sectional shape perpendicular to the longitudinal centerline 42.The generally arcuate cross-sectional shape of the raised bead seal 26 results in an elastic response to a load in a direction perpendicular to the plate structure 20. The raised bead seal 26 can have any desirable cross-sectional shape. For example, the raised bead seal 26 can have a semicircular shape that projects from the flat section 34 of the first plate 30.

[0030] As in Fig. As shown in Figure 1, the exemplary embodiment of the raised bead seal 26 is nonlinear. However, other embodiments of the raised bead seal 26 may be linear. As shown in the exemplary embodiment, the entire centerline 42 of the raised bead seal 26 can be considered nonlinear. However, it should be clear that sections of the centerline 42 shown in the exemplary embodiment can be considered linear. Accordingly, the centerline 42 comprises linear and nonlinear sections. The nonlinear sections can be considered curved sections with a defined curvature.

[0031] The tunnel 28 projects from the reference plane 36 and extends along path 44 on the reference plane 36. Path 44 of the tunnel 28 is linear. As such, the tunnel 28 runs in a straight line and does not deviate to the right or left from the straight line defined by path 44 of the tunnel 28. The tunnel 28 intersects the raised bead seal 26. The tunnel 28 can have any desirable cross-sectional shape. For example, the tunnel 28 can have a semicircular shape projecting from the flat section 34 of the first plate 30. This tunnel 28 is in fluid contact with the edge 38 of the first plate 30, which is located on a first side 46 of the raised bead seal 26. More precisely, the tunnel 28 is in fluid communication with the edge 38 of the first plate 30, which defines the opening 24, and as such the tunnel 28 is in fluid communication with the opening 24.The tunnel 28 is also in fluid connection with the port 40, which is located on a second side 48 of the raised bead seal 26. As mentioned above, the path 44 of the tunnel 28 is linear and extends along a straight line. As such, the path 44 extends from the first side 46 of the raised bead seal 26 along the straight line defined by the linear path 44 across the bead seal to the second side 48 of the bead seal, so that the portion of the tunnel 28 on the first side 46 of the raised bead seal 26 aligns with the portion of the tunnel 28 on the second side 48 of the raised bead seal 26 along the straight, linear path 44.

[0032] The path 44 of the tunnel 28 and the centerline 42 of the raised bead seal 26 intersect, forming a first angle of intersection 50 and a second angle of intersection 52 on the reference plane 36. The first angle of intersection 50 and the second angle of intersection 52 are adjacent angles. In other words, the first angle of intersection 50 and the second angle of intersection 52 are directly next to each other and share at least one ray or side. Furthermore, the first angle of intersection 50 and the second angle of intersection 52 are supplementary angles. As such, the sum of the first angle of intersection 50 and the second angle of intersection 52 equals one hundred and eighty degrees (180°).

[0033] One of the angles of intersection, 50°, and the second angle of intersection, 52°, is an obtuse angle, and the other of the angles of intersection, 50°, and 52°, is an acute angle. As in Fig. As shown in Figure 2, the exemplary embodiment of the plate assembly 20 defines the first cutting angle 50 as the acute angle, i.e. an angle less than ninety degrees (90°) and the second cutting angle 52 as the obtuse angle, i.e. an angle greater than ninety degrees (90°).

[0034] The increased bead seal 26 exhibits stiffness. As used herein, the term “stiffness” can be defined as the extent or magnitude of resistance to deformation in response to an applied force 54 (in Fig. 3) are defined as being perpendicular to a reference plane 36. The stiffness of the raised bead seal 26 increases with a decrease in the value of the acute angle. Conversely, the stiffness of the raised bead seal 26 decreases with an increase in the value of the acute angle.

[0035] To achieve a good seal, the raised bead seal 26 must react to the applied force 54 by generating a resulting sealing force 56 (in Fig. 3) is provided, which is evenly distributed over the entire length of the raised bead seal 26. If one section of the raised bead seal 26 has a higher stiffness than another section, then the section with the higher stiffness will provide a higher sealing force, while the section with the lower stiffness will provide a lower sealing force. Accordingly, it is important to make the stiffness of the raised bead seal 26 as uniform as possible along its entire length in order to provide a uniform sealing force along its entire length.

[0036] As mentioned above, both the raised bead seal 26 and the tunnel 28 project upwards from the flat section 34 of the first plate 30 and intersect each other. It should be noted that the stiffness of the raised bead seal 26 is at least partially dependent on its cross-sectional shape and / or structure. However, in the area of ​​the raised bead seal 26 that is intersected by the tunnel 28, the cross-sectional shape of the raised bead seal 26 is altered. Essentially, the side walls of the raised bead seal 26 are removed where the tunnel 28 intersects it, which weakens the raised bead seal 26 and reduces its stiffness at the center of the intersection.The geometric structure formed where the side walls of the raised bead seal 26 and the tunnel 28 connect can, however, exhibit higher stiffness than the cross-sectional stiffness of the raised bead seal 26 alone provides. Accordingly, the local corners or four quadrants formed by the intersection of the tunnel 28 and the raised bead seal 26 can exhibit higher stiffness than other sections of the raised bead seal 26, while the center of the interface between the tunnel 28 and the raised bead seal 26, near the intersection of path 44 and centerline 42, can exhibit lower stiffness than other sections of the raised bead seal 26. By angling path 44 of the tunnel 28 relative to the centerline 42 of the raised bead seal 26, the stiffness of the raised bead seal 26 is made more uniform across the intersection area between the tunnel 28 and the raised bead section.

[0037] As mentioned above, the exemplary embodiment of the plate assembly 20 shown in the FIG. demonstrates that the first cutting angle 50 is an acute angle. Therefore, the first cutting angle 50 is not a right angle with a value less than ninety degrees (90°), and the second cutting angle 52 is not a right angle with a value greater than ninety degrees (90°). If the intersection point between tunnel 28 and the raised bead seal 26 occurs within a curved section of the centerline 42, then the first cutting angle 50 is measured between the path 44 and a tangent 58 of the centerline 42 at the intersection of the centerline 42 and the path 44.

[0038] The values ​​of the first cutting angle 50 and the second cutting angle 52 depend on the geometry of the first plate 30, including, among other things, the location of the raised bead seal 26 relative to the edge 38 of the opening 24, the location of the connection 40, etc. Generally, the smallest possible value of the acute angle will provide the greatest uniformity for the stiffness of the raised bead seal 26. However, as mentioned above, the geometry of the plate assembly 20 may limit the amount by which the path 44 of the tunnel 28 can be angled relative to the centerline 42 of the raised bead seal 26. Preferably, the acute angle is less than seventy-five degrees (75°). Specifically, the acute angle is less than forty-five degrees (45°). However, in some embodiments, this may not be achievable.Accordingly, it should be clear that any reduction of the acute angle to a value less than ninety degrees (90°) should provide improvements in the uniformity of stiffness in the increased bead seal 26.

[0039] As mentioned above, the plate assembly 20 can be configured as a bipolar plate assembly 60, in which two plates are combined and connected to each other, as is known in the art. With reference to Fig.Figure 3 shows an example of the bipolar plate assembly 60. The second plate 32 includes a planar section 62 on the reference plane 36 opposite the first planar section 34 of the first plate 30. The second plate 32 is attached to the first plate 30 and is a mirror image of the first plate 30 across the reference plane, with the first plate 30 and the second plate 32 forming the bipolar plate assembly 60. Accordingly, it should be clear that the second plate 32 is shaped and / or formed to include the raised bead seal 26 and the tunnel 28, as described above with reference to the first plate 30, with the path 44 of the tunnel 28 being angled relative to the centerline 42 of the raised bead seal 26.

[0040] A method for manufacturing the plate assembly 20 for a fuel cell is also provided. The method involves forming the first plate 30 with the raised bead seal 26, which projects from the reference plane 36 and extends along the centerline 42 on the reference plane 36. The first plate 30 is further or simultaneously formed to include the tunnel 28. As described above, the tunnel 28 also projects from the reference plane 36 and extends along the path 44 on the reference plane 36. The first plate 30, including the raised bead seal 26 and the tunnel 28, can be formed in any suitable manner. For example, the first plate 30 can be manufactured from a thin sheet by stamping or a similar process known to those skilled in the art.

[0041] As described above, the relative orientation between the path 44 of the tunnel 28 and the centerline 42 of the raised bead seal 26 influences the stiffness of the raised bead seal 26 at the interface between the tunnel 28 and the raised bead seal 26. Accordingly, the relative orientation between the path 44 of the tunnel 28 and the centerline 42 of the raised bead seal 26 is designed to control the value of the first cut angle 50° and the second cut angle 52°, thereby influencing the stiffness of the raised bead seal 26. As mentioned above, the stiffness of the raised bead seal 26 increases with a decrease in the value of the acute angle, and decreases with an increase in the value of the acute angle.

Claims

Plate assembly (20) for a fuel cell, the plate assembly (20) comprising: a first plate (30) with a planar section (34) defining a reference plane (36); a raised bead seal (26) projecting from the reference plane (36) and extending along a centerline (42) on the reference plane (36); a tunnel (28) projecting away from the reference plane (36) and extending along a path (44) on the reference plane (36), the tunnel (28) intersecting the raised bead seal (26); the path (44) and the centerline (42) intersecting and forming a first angle of intersection (50) on the reference plane (36); the first angle of intersection (50) being non-right angles; the path (44) of the tunnel (28) being linear; and the centerline (42) of the raised bead seal (26) being linear includes sections and non-linear sections;wherein the first angle of intersection (50) between the path (44) and a tangent (58) of the center line (42) is measured at the intersection of the center line (42) and the path (44); wherein the intersection of the path (44) and the center line (42) forms a second angle of intersection (52) in the reference plane (36); wherein the first angle of intersection (50) and the second angle of intersection (52) are complementary angles; wherein the first angle of intersection (50) and the second angle of intersection (52) are adjacent angles; and wherein one of the angles of intersection (50) and the second angle of intersection (52) is an obtuse angle and the other of the angles of intersection (50) and the second angle of intersection (52) is an acute angle; characterized in that the acute angle is less than forty-five degrees. Plate assembly (20) according to claim 1, wherein the first plate (30) defines an edge (38) and a connection (40) through the first plate (30), and wherein the tunnel (28) is in fluid communication with the edge (38) of the first plate (30) on a first side (46) of the raised bead seal (26) and in fluid communication with the connection (40) on a second side (48) of the raised bead seal (26).

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