Impact energy attenuation system for fuel cell

Abstract

The invention relates to an impact energy attenuation system for a fuel cell. A bipolar plate for a fuel cell system includes a rigid plate having a first side defining a first passage, a second side defining a second passage, a sealing bead, and a peripheral edge; and an impact energy attenuation system. A sealing bead is disposed proximate a peripheral edge of the rigid plate, and an impact energy attenuation system is disposed proximate the peripheral edge. The impact energy attenuation system includes first energy attenuation beads and second energy attenuation beads, where each of the first energy attenuation beads has a first compression modulus and a first zero compression height, and where each of the second energy attenuation beads has a second compression modulus and a second zero compression height. The first compression modulus is greater than the second compression modulus, and the second zero compression height is greater than the first zero compression height.

Description

Technical Field

[0001] A fuel cell is an electrochemical device that converts the chemical energy of a fuel (e.g., hydrogen) into electrical power by an electrochemical reaction. A fuel cell includes an anode, a cathode, and an electrolyte disposed between the anode and the cathode, and a fuel delivery system that supplies the fuel (e.g., hydrogen) to the anode. During operation, a fuel such as hydrogen may enter the anode, and oxygen or air may enter the cathode. Hydrogen may dissociate in the anode to generate free hydrogen protons and electrons. The hydrogen protons may then reach the cathode through the electrolyte, and react with the oxygen and electrons in the cathode to generate water. In addition, the electrons from the anode may be directed through an electrical load to do work by converting electrical power into mechanical power. A plurality of fuel cells may be combined to form a fuel cell stack, thereby generating a desired fuel cell power output. For example, a fuel cell for a vehicle may include many stacked fuel cells. A type of fuel cell includes a polymer electrolyte membrane fuel cell (PEMFC). Background Art

[0002] Fuel cells are used to generate electrical energy in vehicles. Electrical energy can be stored in batteries and / or directed to motors to provide motive power to vehicles. In fuel cells such as polymer electrolyte membrane fuel cells, an ion transport membrane is sandwiched between a pair of catalytic electrodes, which are further sandwiched between two gas diffusion layers to form a membrane electrode assembly (MEA). When a first reactant in the form of a gaseous reductant such as hydrogen is introduced into the anode electrode and ionized through a first gas diffusion layer, an electrochemical reaction occurs. The first reactant then passes through an ion transport material. After passing through the ion transport material, the first reactant combines with a second reactant in the form of a gaseous oxidant such as oxygen, which has been introduced into the cathode through a second gas diffusion layer. The combination of reactants forms water. The electrons released in the ionization advance to the cathode in the form of a DC current via an external circuit, which may include a load such as an electric motor.

[0003] The MEA can be formed into a stack to form a fuel cell. Adjacent MEAs are separated from each other by a series of reactant channels in the form of gas-impermeable bipolar plates. In addition to facilitating the flow of reactants, the bipolar plates also provide support for the stack. Each bipolar plate includes one or more sealing beads that prevent reactants from leaving the MEA. During a collision event, the leading cell (i.e., those cells closest to the impact point) experiences an effective positive acceleration force, and the trailing cell (i.e., those cells farthest from the impact point) experiences an effective negative acceleration force. Therefore, the leading cell tends to experience an increased sealing force, while the trailing cell tends to experience a reduced sealing force.

[0004] As the sealing force on the leading cell increases, the risk of exceeding the upper limit of the seal also increases. Similarly, as the sealing force on the trailing seal decreases, the risk of being below the minimum sealing force also decreases. Exceeding the upper limit of the sealing force or being below the lower limit of the sealing force may cause the sealing bead to deform. The deformation of the sealing bead affects the integrity of each cell and may cause leakage of the first reactant, the second reactant and / or the coolant. Therefore, it is desirable to provide a fuel cell with an energy decay sealing bead to improve structural integrity and impact resistance. Summary of the invention

[0005] A bipolar plate for a fuel cell system is disclosed, the bipolar plate comprising: a rigid plate having a first side defining a first plurality of passages, a second side defining a second plurality of passages, a sealing bead and a peripheral edge; and an impact energy attenuation system. The sealing bead is arranged near the peripheral edge of the rigid plate; and the impact energy attenuation system is arranged near the peripheral edge. The impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads, wherein each of the plurality of first energy attenuation beads has a first compression modulus and a first zero compression height, and wherein each of the plurality of second energy attenuation beads has a second compression modulus and a second zero compression height. The first compression modulus is greater than the second compression modulus, and the second zero compression height is greater than the first zero compression height.

[0006] One aspect of the present disclosure may include a first plurality of attenuation beads and a second plurality of attenuation beads protruding orthogonally to a plane defined by the rigid plate.

[0007] Another aspect of the present disclosure may include each of the plurality of first attenuation beads having one of a circular shape, an annular shape, a rectangular shape, a serpentine shape, an elliptical shape, or a teardrop shape.

[0008] Another aspect of the present disclosure may include each of the plurality of second attenuation beads having one of a circular shape, an annular shape, a rectangular shape, a serpentine shape, an elliptical shape, or a teardrop shape.

[0009] Another aspect of the present disclosure may include a first plurality of dampening beads and a second plurality of dampening beads arranged to combine to compress prior to reaching a low load bead height of the sealing bead.

[0010] Another aspect of the present disclosure may include a first plurality of energy attenuating beads and a second plurality of energy attenuating beads of an impact energy attenuation system disposed on a bipolar plate between a sealing bead and a peripheral edge.

[0011] Another aspect of the present disclosure may include a first plurality of energy attenuating beads and a second plurality of energy attenuating beads of an impact energy attenuation system formed on a bipolar plate between a sealing bead and a peripheral edge.

[0012] Another aspect of the present disclosure may include arranging a first plurality of energy attenuating beads on a bipolar plate relative to a second plurality of energy attenuating beads to define a plurality of channels between the sealing bead and a peripheral edge of the bipolar plate.

[0013] Another aspect of the present disclosure may include a plurality of first attenuation beads and a plurality of second attenuation beads being arranged alternately.

[0014] Another aspect of the present disclosure may include a first plurality of attenuation beads interspersed with a second plurality of attenuation beads.

[0015] Another aspect of the present disclosure may include the rigid plate being fabricated from one of a metal or a polymer material.

[0016] Another aspect of the present disclosure may include a fuel cell system including a plurality of bipolar plate assemblies arranged in a stack, wherein each of the bipolar plate assemblies includes: a rigid plate having a first side defining a first plurality of passages, a second side defining a second plurality of passages, a first subgasket, a second subgasket, a sealing bead, a peripheral edge; and an impact energy attenuation system. A plurality of coolant passages are defined between the first subgasket and the second subgasket. The sealing bead is arranged near the peripheral edge of the rigid plate, and the sealing bead is arranged to seal against the first subgasket and the second subgasket. The impact energy attenuation system is disposed near the peripheral edge of the rigid plate. The impact energy attenuation system includes a plurality of first energy attenuation beads and a plurality of second energy attenuation beads. Each of the first energy attenuation beads has a first compression modulus and a first zero compression height, and each of the second energy attenuation beads has a second compression modulus and a second zero compression height. The first compression modulus is greater than the second compression modulus, and the second zero compression height is greater than the first zero compression height.

[0017] The present invention provides the following technical solutions.

[0018] Technical Solution 1. A bipolar plate for a fuel cell system, the bipolar plate comprising:

[0019] a rigid plate having a first side defining a first plurality of passageways, a second side defining a second plurality of passageways, a sealing bead, and a peripheral edge; and

[0020] Impact energy attenuation system;

[0021] wherein the sealing beads are arranged near the peripheral edge of the rigid plate; and

[0022] wherein the impact energy attenuation system is arranged near the peripheral edge;

[0023] Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads;

[0024] wherein each of the plurality of first energy attenuation beads has a first compression modulus and a first zero compression height;

[0025] wherein each of the plurality of second energy attenuation beads has a second compression modulus and a second zero compression height;

[0026] wherein the second zero compression height is greater than the first zero compression height; and

[0027] Wherein, the first compression modulus is greater than the second compression modulus.

[0028] Technical Solution 2. A bipolar plate according to Technical Solution 1, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads protrude orthogonally to a plane defined by the rigid plate.

[0029] Technical Solution 3. A bipolar plate according to Technical Solution 2, wherein each of the plurality of first energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape.

[0030] Technical Solution 4. A bipolar plate according to Technical Solution 2, wherein each of the plurality of second energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape.

[0031] Technical Solution 5. The bipolar plate according to Technical Solution 2, wherein the plurality of first energy attenuation beads have a circular shape.

[0032] Technical Solution 6. The bipolar plate according to Technical Solution 1, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads are arranged to be combined for compression before reaching a low load bead height of the sealing bead.

[0033] Technical Solution 7. A bipolar plate according to Technical Solution 1, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads of the impact energy attenuation system are arranged on the bipolar plate between the sealing beads and the peripheral edge.

[0034] Technical Solution 8. A bipolar plate according to Technical Solution 1, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads of the impact energy attenuation system are formed on the bipolar plate between the sealing bead and the peripheral edge.

[0035] Technical Solution 9. A bipolar plate according to Technical Solution 8, wherein the plurality of first energy attenuation beads are arranged on the bipolar plate relative to the plurality of second energy attenuation beads to define a plurality of channels between the sealing beads and the peripheral edge of the bipolar plate.

[0036] Technical Solution 10. The bipolar plate according to Technical Solution 1, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads are arranged alternately.

[0037] Technical Solution 11. A bipolar plate according to Technical Solution 1, wherein the first plurality of energy attenuation beads are interleaved with the second plurality of energy attenuation beads.

[0038] Technical Solution 12. A bipolar plate according to Technical Solution 1, wherein the rigid plate is made of one of metal or polymer materials.

[0039] Technical Solution 13. A fuel cell system, comprising:

[0040] a plurality of bipolar plate assemblies arranged in a stack;

[0041] wherein each of the bipolar plate assemblies includes a rigid plate having a first side defining a first plurality of passages, a second side defining a second plurality of passages, a first subgasket, a second subgasket, a sealing bead, a peripheral edge, and an impact energy attenuation system;

[0042] wherein a plurality of coolant passages are defined between the first subgasket and the second subgasket;

[0043] wherein the sealing bead is arranged adjacent the peripheral edge of the rigid plate, and wherein the sealing bead is arranged to seal against the first subgasket and the second subgasket;

[0044] wherein the impact energy attenuation system is disposed near the peripheral edge of the rigid plate,

[0045] Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads;

[0046] wherein each of the first energy attenuation beads has a first compression modulus and a first zero compression height;

[0047] wherein each of the second energy attenuation beads has a second compression modulus and a second zero compression height;

[0048] wherein the second zero compression height is greater than the first zero compression height; and

[0049] Wherein, the first compression modulus is greater than the second compression modulus.

[0050] Technical Solution 14. A fuel cell system according to Technical Solution 13, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads protrude orthogonally to a plane defined by the rigid plate.

[0051] Technical Solution 15. A fuel cell system according to Technical Solution 14, wherein each of the plurality of first energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape, and wherein each of the plurality of second energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape.

[0052] Technical Solution 16. A fuel cell system according to Technical Solution 13, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads are combined for compression before reaching a low load bead height of the sealing beads.

[0053] Technical Solution 17. A fuel cell system according to Technical Solution 13, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads of the impact energy attenuation system are arranged on the bipolar plate between the sealing beads and the peripheral edge of the bipolar plate.

[0054] Technical Solution 18. A fuel cell system according to Technical Solution 13, wherein the plurality of first energy attenuation beads are arranged on the bipolar plate relative to the plurality of second energy attenuation beads to define a plurality of channels between the sealing beads and the peripheral edge of the bipolar plate.

[0055] Technical Solution 19. A bipolar plate for a fuel cell system, the bipolar plate comprising:

[0056] a rigid plate having a first side defining a first plurality of passages, a second side defining a second plurality of passages, and a peripheral edge; and

[0057] Impact energy attenuation system;

[0058] wherein the impact energy attenuation system is arranged near the peripheral edge;

[0059] Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads;

[0060] wherein each of the first plurality of energy attenuation beads has a first compression modulus and a first zero compression height; and

[0061] wherein each of the plurality of second energy attenuation beads has a second compression modulus and a second zero compression height; and

[0062] Wherein, the second zero compression height is greater than the first zero compression height.

[0063] Technical Solution 20. A bipolar plate according to Technical Solution 19, wherein the plurality of first energy attenuation beads and the plurality of second energy attenuation beads protrude orthogonally to the plane defined by the rigid plate; wherein each of the plurality of first energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape; and wherein each of the plurality of second energy attenuation beads has one of a circular shape, annular shape, rectangular shape, serpentine shape, elliptical shape or teardrop shape.

[0064] The above summary of the invention is not intended to represent every possible embodiment or every aspect of the present disclosure. On the contrary, the foregoing summary of the invention is intended to illustrate some of the novel aspects and features disclosed herein. When combined with the accompanying drawings and the appended claims, the above-mentioned features and advantages of the present disclosure and other features and advantages will become apparent from the detailed description of the following representative embodiments and modes for implementing the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0066] Figure 1 A vehicle according to the present disclosure is schematically illustrated.

[0067] Figure 2 A powertrain system for a vehicle including a fuel cell according to the present disclosure is schematically illustrated.

[0068] Figure 3 A perspective cutaway view of a portion of a fuel cell stack assembly according to the present disclosure is schematically illustrated.

[0069] Figure 4 An exploded perspective cutaway view of a portion of a fuel cell stack assembly according to the present disclosure is schematically illustrated.

[0070] Figure 5 Schematically illustrates a diagram taken at line 5-5 according to the present disclosure Figure 3 A cross-sectional view of an embodiment of a fuel cell stack assembly.

[0071] Fig. 6A A top view of a portion of a bipolar plate including an impact energy attenuation system according to the present disclosure is schematically illustrated, including an expanded top view of a portion of the impact energy attenuation system of the bipolar plate.

[0072] Figure 6B Schematically illustrates a reference taken at line 6A-6A according to the present disclosure Fig. 6A A cutaway cross-sectional side view of a portion of an impact energy attenuation system of a bipolar plate is depicted.

[0073] Figure 7 A graph of compression parameters versus load is illustrated for an embodiment of an impact energy attenuation system according to the present disclosure.

[0074] Figure 8 Graphs showing deformation parameters versus load for embodiments of an impact energy attenuation system according to the present disclosure are illustrated.

[0075] Fig.9A and Fig. 9B Schematically illustrated is a detailed cross-sectional side view of an embodiment of elements of an impact energy attenuation system according to the present disclosure.

[0076] FIG. 10A to FIG. 10G Schematically illustrated are top views of various embodiments of elements of an impact energy attenuation system according to the present disclosure.

[0077] FIG. 11A to FIG. 11E Side views of various embodiments of elements of an impact energy attenuation system according to the present disclosure are schematically illustrated.

[0078] The drawings are not necessarily drawn to scale and may present somewhat simplified representations of various preferred features of the present disclosure disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. The details associated with these features will be determined in part by the specific intended application and use environment. DETAILED DESCRIPTION

[0079] As described and shown herein, the components of the disclosed embodiments may be arranged and designed in a variety of different configurations. Therefore, the following detailed description is not intended to limit the scope of the disclosure claimed, but merely represents possible embodiments thereof. In addition, although many specific details are set forth in the following description to provide a thorough understanding of the embodiments disclosed herein, some embodiments may be practiced without some of these details. In addition, for the sake of clarity, some technical materials understood in the related art are not described in detail to avoid unnecessarily obscuring the disclosure.

[0080] For the purpose of convenience and clarity, directional terms such as top, bottom, left, right, up, above, above, below, below, rear and front may be used with respect to the accompanying drawings. These and similar directional terms should not be construed as limiting the scope of the present disclosure. In addition, as shown and described herein, the present disclosure can be implemented without elements not specifically disclosed herein.

[0081] The following detailed description is merely illustrative in nature and is not intended to limit application and use. In addition, there is no intention to be bound by the explicit or implicit theory proposed herein. In all drawings, corresponding reference numerals indicate similar or corresponding parts and features.

[0082] As used herein, the term "system" may refer to one or a combination of multiple mechanical devices arranged to provide the described functionality.

[0083] The use of ordinal numbers such as first, second, and third does not necessarily imply a sequential ranking sense, but rather may distinguish between multiple instances of an action or structure.

[0084] All numerical values ​​of parameters (e.g., amounts or conditions) in this specification, including the appended claims, should be understood to be modified by the word "about", whether or not "about" actually appears before the numerical value. "About" means that the numerical value allows some slight imprecision (close to the exact value to a certain extent; approximately or reasonably close to the value; almost). If the imprecision provided by "about" is not understood in the art to have such ordinary meaning, then the "about" used in this article at least represents the changes that may be produced by the ordinary methods of measuring and using such parameters. In addition, the disclosure of the range includes the disclosure of all values ​​and the ranges further divided within the entire range. Here, each value within the range and the endpoints of the range are disclosed as separate embodiments.

[0085] Referring to the drawings, in which like reference numerals correspond to like or similar components throughout the several views, consistent with embodiments disclosed herein, Figure 1 A vehicle 10 is shown that employs a fuel cell system 30 as part of a powertrain. The vehicle may include, but is not limited to, a mobile platform in the form of a commercial vehicle, an industrial vehicle, an agricultural vehicle, a passenger vehicle, an aircraft, a boat, a train, an all-terrain vehicle, a personal mobility device, a robot, etc., to achieve the purposes of the present disclosure.

[0086] The vehicle 10 includes a body 12 resting on a plurality of wheels, one of which is indicated at 14. The vehicle 10 includes a passenger cabin 16. A power system 20 is operatively connected to one or more of the plurality of wheels 14. Figure 2 , the power system 20 includes an electric motor 24 connected to a fuel cell system 30. The fuel cell system 30 provides electric power based on driver input to operate the electric motor 24. That is, a driver (not shown) sitting in the passenger compartment 16 can request that power be transferred from the electric motor 24 to the wheels 14.

[0087] Figure 3 and Figure 4 A fuel cell system 30 is described according to a non-limiting example. The fuel cell system 30 is formed of a plurality of stacked and interconnected bipolar plate assemblies, including a first bipolar plate assembly 34, a second bipolar plate assembly 36, and a third bipolar plate assembly 38. The number and arrangement of the bipolar plate assemblies may vary. When describing the first bipolar plate assembly 34, reference will be made to Figure 5 And continue to refer to Figure 3 and Figure 4 , while understanding that the second bipolar plate assembly 36 and the third bipolar plate assembly 38 include similar structures.

[0088] The first bipolar plate assembly 34 includes a first subgasket 41 having a first peripheral edge 43 and a first membrane electrode assembly (MEA) 45. The first bipolar plate assembly 34 also includes a second subgasket 48 having a second peripheral edge 50. The second subgasket 48 includes a second MEA 52. Figure 5 As shown in , the second subgasket 48 can define the surface of the second bipolar plate assembly 36 and can also define the surface of the first bipolar plate assembly 34. The bipolar plate 56 is positioned between the first subgasket 41 and the second subgasket 48. The bipolar plate 56 includes a first side 58 defining a cathode side (not separately labeled) and a second side 60 defining an anode side (also not separately labeled). The bipolar plate 56 is a rigid plate made of metal by stamping. Alternatively, the bipolar plate 56 is a rigid plate made of a polymer by injection molding or another process.

[0089] The bipolar plate 56 includes a plurality of corrugations (not individually labeled) forming a first plurality of passages 62 on a first side 58. The first plurality of passages 62 may contain a first reactant or cathode fluid (not shown) in contact with a surface (not individually labeled) of the first MEA 45. The corrugations also form a second plurality of passages 64 at the second side 60. The second plurality of passages 64 may contain a second reactant or anode fluid (not shown) in contact with a surface (also not individually labeled) of the second MEA 52. The bipolar plate 56 also includes a plurality of coolant passages 69, which may contain a coolant that absorbs heat from the fuel cell system 30.

[0090] Further in accordance with a non-limiting example, the bipolar plate 56 includes a plurality of headers 70 in fluid communication with the first plurality of passages 62, the second plurality of passages 64, and the coolant passages 69. More specifically, the plurality of headers 70 include a first reactant inlet 72 and a first reactant outlet 74. The plurality of headers 70 also include a second reactant inlet 76 and a second reactant outlet 78. In addition, the plurality of headers may include a coolant inlet 80 and a coolant outlet 82.

[0091] The bipolar plate 56 is also shown to include a perimeter sealing bead 90 extending completely around the first MEA 45, the second MEA 52, and the first plurality of passages 62, the second plurality of passages 64, and the coolant passages 69. In addition, each of the plurality of headers 70 includes an associated header sealing bead connected to the first reactant inlet 72, the coolant inlet 80, and the second reactant inlet 76, such as shown at 94, 96, and 98. For example, the sealing bead 94 extends completely around the first reactant inlet 72, the sealing bead 96 extends completely around the coolant inlet 80, and the sealing bead 98 extends completely around the second reactant inlet 76. The sealing beads 90, 94, 96, and 98 are disposed between the first subgasket 41 and the second subgasket 48. The sealing bead 90 extends around the first bipolar plate assembly 34. In this way, the sealing bead 90 isolates the first bipolar plate assembly 34 from the ambient fluid. Sealing beads 90 , 94 , 96 , and 98 ensure fluid isolation between the first reactant 72 , the second reactant 76 , and the coolant 80 and / or ambient air.

[0092] During a crash event, the seal bead integrity may be compromised. It would be desirable to provide a fuel cell with an energy attenuating seal bead to improve the seal integrity and crash resistance of a fuel cell seal by having the same effect without changing the size and design of the fuel cell seal.

[0093] Thus, according to a non-limiting example, the first bipolar plate assembly 34 also includes an embodiment of an impact energy attenuation system 100 that is designed to absorb acceleration forces during, for example, a collision event such that the sealing beads 90, 94, 96, and 98 maintain sealing integrity. In a non-limiting example, the impact energy attenuation system 100 may include a first segment 108 extending around a first portion (not separately labeled) of the first peripheral edge 43 and a second segment extending around a second portion (also not separately labeled) of the first peripheral edge 43.

[0094] In a non-limiting example, the sealing beads 90, 94, 96, and 98 are formed of a first material having a first stiffness, and the impact energy attenuation system 100 is formed as described herein to have an additional stiffness greater than the first stiffness. Stiffness is understood to be the amount of vertically applied compressive force required for a unit displacement [nm] of sealing bead deformation [mm] defined as per unit length of the sealing bead.

[0095] Fig. 6A and Figure 6BA portion of an embodiment of a bipolar plate 56 of a first bipolar plate assembly 34 including an embodiment of an impact energy attenuation system 100 is shown. The impact energy attenuation system 100 is disposed between the sealing bead 90 and the peripheral edge 43. The impact energy attenuation system 100 includes a plurality of first energy attenuation beads (first beads) 110 and a plurality of second energy attenuation beads (second beads) 120, wherein the first beads 110 and the plurality of second beads 120 protrude orthogonally to a plane defined by the bipolar plate 56. As shown, the first beads 110 and the plurality of second beads 120 are arranged in a row near the peripheral edge 43. In one embodiment, the plurality of first beads 110 and the plurality of second beads 120 are arranged in an alternating manner, and a plurality of fluid channels 130 are arranged between them. The purpose of the plurality of fluid channels 130 is to facilitate and enable leak detection in the event that one of the sealing beads 90, 94, 96, and 98 is ruptured.

[0096] Each of the first beads 110 has a first compression modulus and a first zero compression height 112, and each of the second beads 120 has a second compression modulus and a second zero compression height 122, wherein the second zero compression height 120 is greater than the first zero compression height 110. Furthermore, the first compression modulus associated with the first beads 110 is greater than the second compression modulus associated with the second beads 120. In other words, the first beads 110 are harder but shorter than the second beads 120.

[0097] In one embodiment, the first bead 110 and the second bead 120 are configured in a ring shape, and as depicted, the first bead 110 is harder but shorter than the second bead 120 .

[0098] Alternatively, the first bead 110 and the second bead 120 may be configured in other shapes, examples of which are shown in FIG. FIG. 10A to FIG. 10G and FIG. 11A to FIG. 11E As shown, the first bead 110 is harder but shorter than the second bead 120 .

[0099] In addition, although not explicitly illustrated, it is contemplated that an embodiment of the impact energy attenuation system 100 disposed between the sealing bead 90 and the peripheral edge 43 may include a plurality of first energy attenuation beads, a plurality of second energy attenuation beads, and a plurality of third, fourth, fifth, or more energy attenuation beads arranged near the peripheral edge 43, wherein the first energy attenuation beads are harder but shorter than the second energy attenuation beads, the second energy attenuation beads are harder but shorter than the third energy attenuation beads, the third energy attenuation beads are harder but shorter than the fourth energy attenuation beads, and so on.

[0100] In one embodiment, and as shown, each of the plurality of first beads 110 has a first compression modulus or sealing force to achieve a first stiffness, and each of the plurality of second beads 120 has a second compression modulus to achieve a second stiffness, wherein the first compression modulus is greater than the second compression modulus.

[0101] Figure 7 An embodiment of a first compression modulus 710 associated with a first bead 110 relative to a second compression modulus 720 associated with a second bead 120 is diagrammatically illustrated, with a compression height 702 being plotted on the horizontal axis relative to a compression load 704 plotted on the vertical axis. As illustrated and as designed, within a range between a high-load bead height 740 and a low-load bead height 750, the first compression modulus 710 associated with the first bead 110 and the second compression modulus 720 associated with the second bead 120 overlap.

[0102] Figure 8 The relationship of the compressed bead height 802 to the compressive load 804 for the system using the embodiment of the first bead 110 and the second bead 120 is graphically illustrated. Line 810 shows the deformation of the first bead 110, and line 820 shows the deformation of the second bead 120. In the embodiment of the impact energy attenuation system 100 by incorporating the first bead 110 and the second bead 120 onto the bipolar plate 56 of the first bipolar plate assembly 34, the impact energy attenuation system 100 achieves a deformation line 830, which enables the attenuation and absorption of impact energy over a wide range without causing the sealing beads 90, 94, 96 and 98 to be exceeded or below their lower limits in the case of the leading cell and the trailing cell, respectively. Avoiding exceeding the upper limit or falling below the lower limit of the sealing beads 90, 94, 96 and 98 advantageously avoids or minimizes leakage. Due to the combined possibilities of MEA thickness tolerances and sealing bead height tolerances, the assembled stack has sealing beads 90, 94, 96 and 98 that can be compressed within a range between the high load bead height 740 and the low load bead height 750. In order for the impact energy attenuation bead to mitigate the unloading in the trailing seal during a crash event when the seal bead is assembled at the low load bead height 750, the first attenuation bead 110 and the plurality of second attenuation beads 120 are advantageously arranged to be combined to be compressed before reaching the low load bead height of the seal bead. In addition, in order for the impact energy attenuation bead to mitigate the overloading in the leading seal during a crash event when the seal bead is assembled at the high load bead height 740, the first attenuation bead and the plurality of second attenuation beads are advantageously arranged to be combined to be compressed before reaching the high load bead height of the seal bead.

[0103] In one embodiment, each of the second beads 120 achieves the second compression modulus by being arranged as a relatively high protrusion from the surface of the bipolar plate 56. In one embodiment, each of the first beads 110 achieves the first compression modulus by being arranged as a relatively short protrusion from the surface of the bipolar plate 56, the protrusion being orthogonal to a plane defined by the rigid plate of the bipolar plate 56.

[0104] In one embodiment, and as shown, each of the first plurality of beads 110 and the second plurality of beads 120 are formed by molding or deforming the material of the bipolar plate 56 orthogonal to a plane defined by the rigid plate.

[0105] Alternatively, each of the first plurality of beads 110 and the second plurality of beads 120 is formed by applying a material capable of providing support to the bipolar plate 56 , wherein the material is configured to provide the necessary first and second compression moduli.

[0106] Fig.9A and Fig. 9B A cross-sectional side view of an embodiment of one of the first beads 100 is schematically illustrated. Fig.9A A cross-sectional side view of a first energy attenuation bead 900A having a dimple shape with a convex outer portion 901A and a concave inner portion 902A is schematically illustrated. Fig. 9B A cross-sectional side view of a first energy attenuation bead 900B having a convex shape with a convex inner portion 901B and a convex outer portion 902B is schematically illustrated.

[0107] FIG. 10A to FIG. 10G Schematically illustrates top views of various embodiments of the arrangement, placement, and size-relative size of first beads 110 and second beads 120 with intervening channels 130 on the surface of the bipolar plate 56 relative to the first peripheral edge 43. FIG. 10A to FIG. 10G In each of the described and illustrated embodiments, the plurality of first beads 110 have a first compression modulus or sealing force to achieve a first stiffness, and the plurality of second beads 120 have a second compression modulus to achieve a second stiffness, wherein the first compression modulus is greater than the second compression modulus. In addition, the plurality of first beads 110 have a first compression modulus and a first zero compression height, and the plurality of second beads 120 have a second compression modulus and a second zero compression height, wherein the second zero compression height is greater than the first zero compression height. In addition, the first compression modulus associated with the first beads 110 is greater than the second compression modulus associated with the second beads 120. In other words, the first beads 110 are harder but shorter than the second beads 120. In addition, although the first beads 110 and the second beads 120 are illustrated and described, it should be understood that some embodiments may also include a third bead, and some embodiments may also include a third and fourth bead, and so on, according to the concepts described herein.

[0108] Fig. 10A A top view schematically illustrates an embodiment of the arrangement, placement, and sizing of first and second beads 110A, 120A with intervening channels 130A on a surface of a bipolar plate 56A relative to a first peripheral edge 43A, wherein the first and second beads 110A, 120A are arranged in a serpentine shape.

[0109] Fig. 10B Schematically illustrates a top view of an embodiment of the arrangement, placement, and size-related dimensions of first beads 110B and second beads 120B with intervening channels 130B on the surface of a bipolar plate 56B relative to a first peripheral edge 43B, wherein the first beads 110B and the second beads 120B are arranged in an elliptical shape with the major axis of the elliptical shape parallel to the first peripheral edge 43B. Fig. 10B As shown, the first bead 110B, the second bead 120B and the channel 130B can be of equal size. In one embodiment, the long axis of the first bead 110B and the second bead 120B are equidistant from the first peripheral edge 43B. In one embodiment, the oval shape has a concave configuration, i.e., a convex outer portion and a concave inner portion, similar to Fig.9A In one embodiment, the elliptical shape has a convex shape, similar to Fig. 9B As shown in .

[0110] Fig. 10C A top view of an embodiment of the arrangement, placement, and relative sizing of first and second beads 110C, 120C with an intervening channel 130C on a surface of a bipolar plate 56C is schematically illustrated, wherein the first and second beads 110C, 120C are arranged in an elliptical shape with the major axis of the elliptical shape parallel to the first peripheral edge 43C. The sizes of the first and second beads 110C, 120C and the channel 130B can vary. In one embodiment, the major axis of the first and second beads 110B, 120B are equidistant from the first peripheral edge 43C. In one embodiment, the elliptical shape has a dimpled configuration, i.e., has a raised outer portion and a recessed inner portion, similar to Fig.9A In one embodiment, the elliptical shape has a convex shape, similar to Fig. 9B As shown in .

[0111] Fig. 10D A top view of an embodiment of the arrangement, placement, and size-related dimensions of a first bead 110D and a second bead 120D with an intervening channel 130D on a surface of a bipolar plate 56D relative to a first peripheral edge 43D is schematically illustrated, wherein the first bead 110D and the second bead 120D are arranged in an elliptical shape, a first long axis associated with the first bead 110D is parallel to the first peripheral edge 43D, and a second long axis associated with the second bead 120D is orthogonal to the first peripheral edge 43D. In alternative embodiments, the first long axis associated with the first bead 110D may be skewed to the left, or skewed to the right, or alternately skewed to the left and right relative to the first peripheral edge 43D.

[0112] Fig.10EA top view of an embodiment of the arrangement, placement, and size-related dimensions of a first bead 110E and a second bead 120E with an intervening channel 130E on a surface of a bipolar plate 56E relative to a first peripheral edge 43E is schematically illustrated, wherein the first bead 110E is arranged in an elliptical shape with its long axis parallel to the first peripheral edge 43E, and the second bead 120E is arranged in an elliptical shape with its long axis perpendicular to the peripheral edge 43E and offset from the first peripheral edge 43E relative to the first bead 110E. Alternatively, one or both of the first bead 110E and the second bead 120E may be configured to have a circular shape.

[0113] Fig.10F A top view of an embodiment of the arrangement, placement, and size-related dimensions of a first bead 110F and a second bead 120F having an intermediate channel 130F on a surface of a bipolar plate 56F relative to a first peripheral edge 43F is schematically illustrated, wherein the first bead 110F and the second bead 120F are arranged in a teardrop shape having rounded ends and opposing vertices. As shown, the vertices of the first bead 110F and the second bead 120F are arranged to face away from the first peripheral edge 43F, as shown. Alternatively, the vertices of the first bead 110F and the second bead 120F can be arranged to face the left side relative to the first peripheral edge 43F, arranged to face alternately to the left and right sides relative to the first peripheral edge 43F, or arranged to face alternately toward and away from the first peripheral edge 43F. In one embodiment, the teardrop shape has a dimpled configuration, i.e., having a raised outer portion and a recessed inner portion, similar to Fig.9A In one embodiment, the teardrop shape has a convex shape similar to Fig. 9B As shown in .

[0114] Figure 10G A top view of an embodiment of the arrangement, placement, and size-related dimensions of a first bead 110G and a second bead 120G having an intermediate channel 130G on a surface of a bipolar plate 56G relative to a first peripheral edge 43G is schematically illustrated, wherein the first bead 110G is arranged in an elliptical shape with its long axis parallel to the first peripheral edge 43G, and the second bead 120G is arranged in a rectangular shape with its long axis orthogonal to the first peripheral edge 43G.

[0115] FIG. 11A to FIG. 11E Various side view arrangements of embodiments of first beads 110 and second beads 120 are schematically illustrated, including a dimpled bead 1100A ( Fig.11A )、Multi-step beads 1100B( Fig. 11B ), including a relatively asymmetric bead with a dimple bead 1100C facing a multi-step bead 1101C ( Fig. 11C ), a combination of opposing concave beads including a first concave bead 1100D facing a second concave bead 1101D having a different diameter ( Fig.11D ), and a combination of an opposing concave bead and a concave dimple bead including a concave dimple bead 1100E facing a concave bead 1101E ( Fig.11E ).

[0116] The detailed description and the accompanying drawings or figures are support and description of the present teaching, but the scope of the present teaching is limited only by the claims. Although the best mode and some of other embodiments for implementing the present teaching have been described in detail, there are various alternative designs and embodiments for practicing the present teaching defined in the claims.

Claims

1. A bipolar plate for a fuel cell system, the bipolar plate comprising: a rigid plate having a first side defining a first plurality of passageways, a second side defining a second plurality of passageways, a sealing bead, and a peripheral edge; and Impact energy attenuation system; wherein the sealing beads are arranged near the peripheral edge of the rigid plate; and wherein the impact energy attenuation system is arranged near the peripheral edge; Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads; wherein each of the plurality of first energy attenuation beads has a first compression modulus and a first zero compression height; wherein each of the plurality of second energy attenuation beads has a second compression modulus and a second zero compression height; wherein the second zero compression height is greater than the first zero compression height; and Wherein, the first compression modulus is greater than the second compression modulus.

2. The bipolar plate according to claim 1, wherein: The first plurality of energy attenuating beads and the second plurality of energy attenuating beads protrude orthogonally to a plane defined by the rigid plate.

3. The bipolar plate according to claim 2, wherein: Each of the first plurality of energy attenuation beads has one of a circular shape, an annular shape, a rectangular shape, a serpentine shape, an elliptical shape, or a teardrop shape.

4. The bipolar plate according to claim 2, wherein: Each of the plurality of second energy attenuation beads has one of a circular shape, an annular shape, a rectangular shape, a serpentine shape, an elliptical shape, or a teardrop shape.

5. The bipolar plate according to claim 2, wherein: The plurality of first energy attenuation beads have a circular shape.

6. The bipolar plate according to claim 1, wherein: The first plurality of energy attenuating beads and the second plurality of energy attenuating beads are arranged to combine to compress prior to reaching a low load bead height of the sealing bead.

7. The bipolar plate according to claim 1, wherein: The first plurality of energy attenuating beads and the second plurality of energy attenuating beads of the impact energy attenuation system are disposed on the bipolar plate between the sealing bead and the peripheral edge.

8. The bipolar plate according to claim 1, wherein: The first plurality of energy attenuating beads and the second plurality of energy attenuating beads of the impact energy attenuation system are formed on the bipolar plate between the sealing bead and the peripheral edge.

9. A fuel cell system comprising: a plurality of bipolar plate assemblies arranged in a stack; wherein each of the bipolar plate assemblies includes a rigid plate having a first side defining a first plurality of passages, a second side defining a second plurality of passages, a first subgasket, a second subgasket, a sealing bead, a peripheral edge, and an impact energy attenuation system; wherein a plurality of coolant passages are defined between the first subgasket and the second subgasket; wherein the sealing bead is arranged adjacent the peripheral edge of the rigid plate, and wherein the sealing bead is arranged to seal against the first subgasket and the second subgasket; wherein the impact energy attenuation system is disposed near the peripheral edge of the rigid plate, Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads; wherein each of the first energy attenuation beads has a first compression modulus and a first zero compression height; wherein each of the second energy attenuation beads has a second compression modulus and a second zero compression height; wherein the second zero compression height is greater than the first zero compression height; and Wherein, the first compression modulus is greater than the second compression modulus.

10. A bipolar plate for a fuel cell system, the bipolar plate comprising: a rigid plate having a first side defining a first plurality of passageways, a second side defining a second plurality of passageways, and a peripheral edge; and Impact energy attenuation system; wherein the impact energy attenuation system is arranged near the peripheral edge; Wherein, the impact energy attenuation system comprises a plurality of first energy attenuation beads and a plurality of second energy attenuation beads; wherein each of the plurality of first energy attenuation beads has a first compression modulus and a first zero compression height; and wherein each of the plurality of second energy attenuation beads has a second compression modulus and a second zero compression height; and Wherein, the second zero compression height is greater than the first zero compression height.

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