fuel cell stack

Abstract

A fuel cell stack (1) is provided, the fuel cell stack (1) comprising at least a fuel cell stack body (2) having a plurality of unit fuel cells, each unit fuel cell including a fuel cell stack body (2) including bipolar plates and membrane electrode assemblies stacked alternately in a stacking direction, first and second terminal plates sandwiching the fuel cell stack body (2), the first and second terminal plates being configured to collect electrical energy generated by the fuel cell stack body (2), a first insulating plate (14) and a second insulating plate sandwiching the terminal plate, the insulating plate (14) being configured to electrically insulate the terminal plate, and first and second end plates (4) sandwiching the insulating plate (14), and at least one first sealing element (18a, 18b) is arranged between at least one insulating plate (14) and the adjacent end plate.

Description

[Technical Field]

[0001] The present invention relates to a fuel cell stack. [Background technology]

[0002] A fuel cell stack typically consists of a stack body containing multiple membrane electrode assemblies (MEAs) separated by so-called bipolar plates (BPPs), a pair of terminal plates that collect the current generated by the stack body, and a pair of end plates that sandwich the terminal plates. To insulate each terminal plate from the adjacent end plate, an insulating plate is provided between each terminal plate and the adjacent end plate.

[0003] The bipolar plate itself typically consists of at least two electrically conductive metal plates, so-called flow field plates, arranged one on top of the other, with a reactant flow field on one side and a cooling fluid flow field on the other. The cooling fluid flow fields thus face each other, while the reactant flow field faces the MEA. Each bipolar plate and / or membrane electrode assembly has inlet manifolds for fuel, oxidant, and coolant, and outlet manifolds for fuel, oxidant, and coolant. In an assembled stack, each manifold extends through the fuel cell stack body, forming tubular channels that carry the respective flow to and from the fuel cell stack. The flow fields of each plate form the active area where electrical energy is generated, and the active area is located between the inlet and outlet manifolds of each individual fuel cell.

[0004] To provide contact protection and / or protection from environmental influences such as water and / or dirt, the fuel cell stack is enclosed in a housing comprising a bottom plate, a top plate and side walls, and sealing elements are provided between the different elements of the housing to achieve a hermetically sealed environment for the fuel cell stack within the housing and ensure a safe and stable operation of the fuel cell stack. Typically, this is ensured by narrow tolerances that define the position and / or seat of the sealing elements used.

[0005] However, the required precision required in manufacturing the stack components to ensure gas-tight sealing of the fuel cell stack, and the number of components included in a fuel cell stack, make manufacturing and assembling a fuel cell stack costly and effort intensive. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fuel cell stack that has improved sealing and can be assembled simply and efficiently. [Means for solving the problem]

[0007] This object is solved by a fuel cell stack according to claim 1.

[0008] Hereinafter, a fuel cell stack is provided that includes a fuel cell stack body with a plurality of unit fuel cells. Each unit fuel cell includes a bipolar plate and a membrane electrode assembly stacked alternately in a stacking direction, and each bipolar plate and / or membrane electrode assembly may include an inlet manifold for at least a fuel, an oxidant, and a coolant, and an outlet manifold for at least a fuel, an oxidant, and a coolant. The manifolds may extend through the fuel cell stack body to form respective tubular channels for supplying respective flows to / from the fuel cell stack, and each unit fuel cell has an active area where electrical energy is generated, the active area being disposed between the inlet and outlet manifolds of each unit fuel cell.

[0009] The fuel cell stack further includes first and second terminal plates sandwiching the fuel cell stack body, the first and second terminal plates configured to collect electrical energy generated by the fuel cell stack body, and first and second end plates sandwiching the fuel cell stack body, at least one end plate may include at least one inlet opening and at least one outlet opening, the at least one inlet opening aligned with one or more inlet channels and the at least one outlet opening aligned with one or more outlet channels.

[0010] The fuel cell stack further includes a first insulating plate disposed between the first end plate and the first terminal plate and a second insulating plate disposed between the second end plate and the second terminal plate, the insulating plate configured to electrically insulate the terminal plate from the end plates. At least one insulating plate may include inlet ducts for at least the fuel, oxidant, and coolant, and outlet ducts for at least the fuel, oxidant, and coolant, configured to fluidly connect the channels to at least one inlet opening and at least one outlet opening. Preferably, the inlet duct and the outlet duct may extend to at least one inlet opening and at least one outlet opening, respectively. For example, each duct may include a protrusion extending into the opening of the at least one end plate. Furthermore, the ducts may be configured to be connected to respective supply lines for the fuel, oxidant, and coolant.

[0011] To provide a fuel cell stack that has sufficient sealing properties against the outside and can be assembled in a simple and efficient manner, at least one first sealing element is arranged between at least one insulating plate and an adjacent end plate. Preferably, the at least one first sealing element is arranged so as to prevent fluid from entering the space between the at least one insulating plate and the adjacent end plate from outside the fuel cell stack. Advantageously, the at least one first sealing element can be arranged on a surface of at least one end plate facing the corresponding insulating plate so that a seal can be easily formed by compressing the at least one sealing element in the stacking direction. Because the fuel cell stack is typically compressed in the stacking direction both during assembly and in the assembled state, precise positioning of the components between which the at least one first sealing element is positioned is not necessary to ensure a sufficient seal.

[0012] According to a further embodiment, at least one end plate includes at least one inlet opening and / or at least one outlet opening for supplying reactants and / or coolant to the fuel cell body, and at least one first sealing element extends around the outer periphery of the at least one inlet opening and / or at least one outlet opening. More specifically, the at least one first sealing element may extend around the entire periphery of the at least one opening. The at least one first sealing element may also surround the at least one opening on a surface having a surface normal parallel to the stacking direction. This allows the fuel cell stack to be effectively sealed against water, dirt, and / or other fluids and / or particles that may enter from the outside.

[0013] Preferably, at least one of the insulating plates includes inlet ducts for the fuel, oxidant, and coolant and outlet ducts for the fuel, oxidant, and coolant, the inlet ducts extending to one inlet opening and / or the outlet ducts extending to one outlet opening, and / or at least one end plate includes an opening for each inlet duct and / or outlet duct of the insulating plates, the inlet duct and the outlet duct extending to a respective opening, each opening being surrounded by a first sealing element, and thus each opening of the end plate is protected by a sealing element.

[0014] Furthermore, the fuel cell stack may further include a housing, the housing including at least a bottom plate and a stack enclosure configured to cover the side of the fuel cell stack. The stack enclosure may be formed by a plurality of side walls forming a hollow box. The housing may also include a top plate. For example, one of the end plates may be configured as the top plate. This reduces the number of parts and the total weight of the fuel cell stack. Alternatively, the stack enclosure may also include a top wall.

[0015] Preferably, at least one second sealing element is disposed between the housing and at least one of the end plates. For example, at least one second sealing element may be disposed between the stack enclosure and one of the end plates. This ensures an airtight seal of the housing and prevents the ingress of water, dirt, and / or other particles and / or fluids into the fuel cell stack. Alternatively or additionally, at least one second sealing element may extend around the periphery of at least one end plate.

[0016] According to a further embodiment, one of the end plates is further configured as a bottom plate of the housing, thereby reducing the overall weight of the fuel cell stack as the bottom plate of the housing can be omitted, and the reduced number of parts simplifies the assembly process, reducing the weight of the completed fuel cell stack and saving costs. Advantageously, the second end plate may also be further configured as a top plate of the housing, thereby reducing the number of parts and thereby even further reducing the weight of the fuel cell stack.

[0017] Preferably, at least one of the end plates includes at least one flange extending around the periphery of the end plate. For example, the flange may provide a fastening interface to the housing to secure the housing to the end plate. The fastening interface may be a threaded hole in the flange, such as a threaded through hole, a blind threaded hole, or a through hole through which a fastening element may pass.

[0018] According to a further embodiment, at least one first sealing element is disposed on a surface of at least one end plate facing a corresponding insulating plate and / or on a surface of at least one insulating plate facing an end plate. Preferably, at least one first and / or second sealing element is fixed to at least one end plate or at least one insulating plate. Fixing at least one first and / or second sealing element to at least one end plate or at least one insulating plate ensures proper positioning of the at least one first and / or second sealing element during assembly of the fuel cell stack, thereby improving stack sealing. Preferably, at least one first and / or second sealing element is disposed in a groove, adhesively bonded, or injection molded. For example, at least one sealing element is a gasket or an O-ring.

[0019] Furthermore, at least one of the first and / or second sealing elements may be elastic elements that are compressed in the stacking direction. This has the advantage that the sealing of the fuel cell stack is ensured solely by gravity and / or compression of the fuel cell stack. For example, the at least one first sealing element may be compressed by weight and / or by at least one compression element configured to provide an additional compression force to the fuel cell stack. The compression element may be a compression band that is wrapped around the fuel cell stack.

[0020] According to a further embodiment, the fuel cell stack includes at least one clamping element configured to apply an additional force to at least one insulating plate, thereby further compressing the at least one first sealing element in the stacking direction. Preferably, the clamping element is secured to at least one end plate by at least one fastening element. For example, the fastening element may be a screw or a bolt. The clamping element may be arranged to clamp at least a portion of an edge of the insulating plate. This ensures that a seal between the insulating plate and the end plate is maintained even if the fuel cell stack becomes uncompressed, for example due to wear and / or breakage.

[0021] Further preferred embodiments are defined in the description and drawings as well as in the dependent claims, in which respect an element described or shown in combination with other elements may also be present alone or in combination with other elements without departing from the scope of protection.

[0022] Preferred embodiments of the invention will now be described with reference to the drawings, which are for illustrative purposes only and are not intended to limit the scope of protection, which is defined solely by the appended claims. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a partial perspective exploded view of a fuel cell stack according to a first embodiment. [Figure 2] FIG. 2 is a side view of the assembled fuel cell stack of FIG. 1. [Figure 3] FIG. 3 is a detailed view of III in FIG. 2. [Figure 4] 1 is a perspective view of a fuel cell stack according to a first embodiment. [Figure 5] FIG. 10 is a partial perspective view of a fuel cell stack according to a second embodiment. [Figure 6] FIG. 6 is a side view of the assembled fuel cell stack of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] In the following, identical or similarly functioning elements are designated with the same reference numerals.

[0025] 1-3 show a fuel cell stack 1 including a fuel cell stack body 2 (FIGS. 2 and 3) with multiple unit fuel cells and end plates 4. Each unit fuel cell includes bipolar plates and membrane electrode assemblies stacked alternately in the stacking direction, such that two bipolar plates sandwich a multilayer membrane electrode assembly. Each bipolar plate and / or membrane electrode assembly includes three inlet manifolds (not shown), i.e., a fuel inlet manifold, an oxidant inlet manifold, and a coolant inlet manifold, and three outlet manifolds (not shown), i.e., a fuel outlet manifold, an oxidant outlet manifold, and a coolant outlet manifold. These manifolds extend through the fuel cell stack 1 to form respective tubular channels for supplying respective flows to and from the fuel cell stack 1. Each unit fuel cell has an active area where electrical energy is generated, and this active area is located between the inlet and outlet manifolds of each unit fuel cell.

[0026] First and second terminal plates 3 are provided to sandwich the fuel cell stack body 2 at the active area to collect and output voltage. The first and second terminal plates 3 are configured to collect electrical energy generated by the fuel cell stack 1, and each terminal plate 3 further includes a power output terminal 6 connectable to an external connector.

[0027] Furthermore, the fuel cell stack 1 is sandwiched between a first end plate 4 and a second end plate 8 (FIG. 2), with the first end plate 4 including an inlet opening 10 and an outlet opening 12. The inlet opening 10 is aligned with an inlet channel, and the outlet opening 12 is aligned with an outlet channel. In the first embodiment shown in FIGS. 1-3, the second end plate 8 is configured to terminate the tubular channels formed by the inlet and outlet manifolds, thereby forming a dead-end fuel cell. However, it is also possible for the outlet openings to be provided in the second end plate 8. Alternatively, the end plate 4 may include an inlet opening for each inlet channel and an outlet opening for each outlet channel.

[0028] A first insulating plate 14 is disposed between the end plate 4 and the first terminal plate 3 to insulate the fuel cell stack body 2 from the end plate 4. Furthermore, a second insulating plate 32 (FIG. 2) may be disposed between the second end plate 8 and the second terminal plate. Both insulating plates 14, 32 are configured to electrically insulate the terminal plate 3 from the end plates 4, 8. Furthermore, the first insulating plate 14 includes fuel, oxidant, and coolant inlet ducts 15a, 15b, and 15c, and fuel, oxidant, and coolant outlet ducts 17a, 17b, and 17c, which are configured to fluidly connect the channels to the inlet opening 10 and the outlet opening 12. Each inlet and outlet duct 15, 17 includes a tubular protrusion 16 extending into the respective inlet opening 10 or outlet opening 12.

[0029] To seal the fuel cell stack 1 from the outside, a first sealing element 18a and a second sealing element 18b are arranged between the first insulating plate 14 and the end plate 4. The first sealing element 18a surrounds the inlet opening 10 in the end plate 4, and the second sealing element 18b surrounds the outlet opening 12 in the end plate.

[0030] As can be seen in FIG. 3 , the sealing elements 18a, 18b are arranged to prevent fluid from entering the space between the insulating plate 14 and the adjacent end plate 4 from outside the fuel cell stack. Furthermore, the sealing elements 18a, 18b are arranged on the surface of the end plate 4 facing the insulating plate 14. This has the advantage that a seal can be easily formed by compressing the sealing elements 18a, 18b in the stacking direction. Because the fuel cell stack 1 is typically compressed in the stacking direction both during assembly and in the assembled state, precise positioning of the insulating plate 14 and the end plate 4 is not necessary to ensure a sufficient seal. If the end plates include openings for each inlet duct 15 and each outlet duct 17, each opening may be surrounded by a sealing element.

[0031] 4 , the end plate 4 is further configured as a bottom plate of the housing 34. This allows an additional bottom plate for the housing 34 to be omitted, thereby reducing the overall weight and number of parts of the fuel cell stack 1. Furthermore, the end plate 4 is provided with a third sealing element 24 that extends around the periphery of the end plate 4 and surrounds the inlet opening 10 and the outlet opening 12. With the third sealing element 24 disposed between the housing 34 and the end plate 4, an airtight seal of the housing 34 can be ensured, and the ingress of water, dirt, and / or other particles and / or fluids into the fuel cell stack 1 can be prevented or at least reduced.

[0032] Additionally, the end plate 4 includes a flange 26 that extends around the outer periphery of the end plate 4. The flange 26 includes a plurality of fastening interfaces 30 for securing the housing to the end plate 4. For example, the fastening interfaces 30 may be threaded holes in the flange, such as threaded through holes, blind threaded holes, or through holes through which fastening elements can pass.

[0033] The sealing elements 18a, 18b and the third sealing element 24 are fixed to the end plates 4 with the aid of respective grooves 20a, 20b and 22. Fixing the sealing elements 18a, 18b, 24 to the end plates or insulating plates 14 ensures proper positioning of the sealing elements 18a, 18b, 24 during the assembly process of the fuel cell stack 1 and allows for improved stack sealing. Alternatively, the sealing elements 18a, 18b, 24 can be adhesively bonded or injection molded to the end plates 4 or insulating plates 14.

[0034] Both sealing elements 18a, 18b and third sealing element 24 are elastic elements that are compressed in the stacking direction, which has the advantage that the sealing of fuel cell stack 1 can be ensured only by gravity and / or compression exerted on fuel cell stack 1 and / or parts of fuel cell stack 1.

[0035] FIG. 5 shows a partial perspective view of a fuel cell stack 1 according to a second embodiment, and FIG. 6 shows a side view thereof. The fuel cell stack 1 of FIG. 1 differs from the fuel cell stack 1 of FIG. 2 in that the fuel cell stack 1 of FIG. 2 includes clamping elements 28 configured to apply additional force to the insulating plates 14, and thus the first and second sealing elements 18a, 18b, in the stacking direction. This improves the sealing of the fuel cell stack 1. As can be seen in FIGS. 5 and 6, the insulating plates 14 include flanges 36 that serve as an interface for the clamping elements 28. The clamping elements 28 may be screws or bolts. The clamping elements 28 are positioned so that they clamp against a portion of the edge of the insulating plates 14. This ensures that the seal between the insulating plates 14 and the end plates 4 is maintained even if the fuel cell stack 1 loosens its compression, for example, due to wear and / or breakage.

[0036] As mentioned above, both sealing elements 18a, 18b and third sealing element 24 are provided on surfaces perpendicular to the stacking direction, so that each sealing element 18, 24 is compressed in the stacking direction both during and after assembly, which has the advantage that precise positioning of the sealing elements is not required, and sufficient sealing of fuel cell stack 1 is ensured. [Explanation of symbols]

[0037] 1. Fuel cell stack 2. Fuel cell stack body 3 Terminal Plate 4 End Plates 6 Power output terminal 8 End Plate 10 Inlet opening 12 Outlet opening 14 Insulation plate 15 Inlet duct 16 protrusions 17 Exit duct 18a, 18b First sealing element 20a,20b groove 22 Additional Grooves 24 Second sealing element 26 flange 28 Clamping Elements 30 Fastening Interface 32 Insulation plate 34 Housing 36 flange

Claims

1. A fuel cell stack (1) comprising at least: a fuel cell stack body (2) having a plurality of unit fuel cells, each unit fuel cell including a bipolar plate and a membrane electrode assembly stacked alternately in a stacking direction; first and second terminal plates (3) sandwiching the fuel cell stack body (2), the first and second terminal plates being configured to collect electrical energy generated by the fuel cell stack body (2); a first insulating plate (14) and a second insulating plate (16) sandwiching the terminal plate (14), the insulating plate (14) being configured to electrically insulate the terminal plate (14); the fuel cell stack (1), including first and second end plates (4) sandwiching the insulating plate (14); A fuel cell stack (1), characterized in that at least one first sealing element (18a, 18b) is arranged between at least one insulating plate (14) and an adjacent end plate (4).

2. 2. The fuel cell stack (1) of claim 1, wherein the at least one first sealing element (18a, 18b) is positioned to prevent fluid from entering the space between the at least one insulating plate (14) and the adjacent end plate (4) from outside the fuel cell stack (1).

3. 3. A fuel cell stack (1) according to claim 1 or 2, wherein the at least one end plate (4) comprises at least one inlet opening (10) and / or at least one outlet opening (12) for supplying reactants and / or coolant to / from the fuel cell body (2), and the at least one first sealing element (18a, 18b) extends around the outer periphery of the at least one inlet opening (10) and / or at least one outlet opening.

4. at least one of the insulating plates (14) comprises inlet ducts (15a, 15b, 15c) for fuel, oxidant and coolant and outlet ducts (17a, 17b, 17c) for fuel, oxidant and coolant, the inlet ducts (15a, 15b, 15c) extending to one inlet opening (10) and / or the outlet ducts (17a, 17b, 17c) extending to one outlet opening (12); and / or the at least one end plate (4) comprises openings (10, 12) for the inlet ducts (15) and / or the outlet ducts (17) of each of the insulating plates (14), the inlet ducts and the outlet ducts extending to their respective openings; 4. The fuel cell stack (1) according to claim 3, wherein each opening (15, 17) is surrounded by a first sealing element (18).

5. 5. The fuel cell stack (1) of claim 1, further comprising a housing, the housing including at least a bottom plate and a stack enclosure configured to cover the sides of the fuel cell stack (2).

6. 6. The fuel cell stack (1) according to claim 5, wherein at least one second sealing element (24) is arranged between the housing and at least one of the end plates.

7. 7. The fuel cell stack (1) according to claim 5 or 6, wherein one of the end plates (4) is further configured as the bottom plate of the housing.

8. 8. A fuel cell stack (1) according to any one of claims 1 to 7, wherein at least one of the end plates (4) has at least one flange (26), the flange (26) extending around the outer periphery of the end plate (4).

9. 9. A fuel cell stack (1) according to any one of claims 1 to 8, wherein the at least one first sealing element (18a, 18b) is arranged on a surface of the at least one end plate (4) facing the corresponding insulating plate (14) and / or on a surface of the at least one insulating plate (14) facing the end plate (4).

10. 10. The fuel cell stack (1) according to any one of claims 1 to 9, wherein the at least first and / or second sealing element (18a, 18b, 24) is fixed to the at least one end plate (4) or the at least one insulating plate (14).

11. 11. The fuel cell stack (1) according to claim 10, wherein the at least one first and / or second sealing element (18a, 18b, 24) is arranged in, adhesively bonded to, or injection molded into a groove (20a, 20b, 22).

12. 12. The fuel cell stack (1) according to any one of the preceding claims, wherein the at least one first and / or second sealing element (18a, 18b, 24) is a gasket or an O-ring.

13. 13. The fuel cell stack (1) according to any one of the preceding claims, wherein the at least one first and / or second sealing element (18a, 18b, 24) is an elastic element compressed in the stacking direction.

14. 14. The fuel cell stack (1) of claim 13, wherein the at least one first sealing element (18a, 18b) is compressed by weight and / or by at least one compression element configured to provide additional compression force to the fuel cell stack (1).

15. 15. A fuel cell stack (1) as described in any one of claims 1 to 14, wherein the fuel cell stack includes at least one clamp element (28) configured to apply additional force to the at least one insulating plate (14), thereby further compressing the at least one first sealing element (18a, 18b) in the stacking direction, and preferably the clamp element (28) is fixed to the at least one end plate (4) with the at least one fastening element.

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