HOUSING FOR A STACK OF FUEL CELLS

Description

[0001] The present invention relates to a housing for a fuel cell stack.

[0002] WO 03 / 094275 A1 discloses a fuel cell stack with end plates to which side plates are welded. Furthermore, EP 1 597 790 B1 discloses an end plate for a stack of fuel cells with a convex pressure shield.

[0003] A key objective of the technology disclosed here is to reduce or eliminate the disadvantages of previously known solutions. Furthermore, there is a need to provide a comparatively compact housing that, despite its low weight and volume, securely clamps the individual fuel cells of the fuel cell stack and reliably compensates for any length tolerances. There is also a need to provide a housing with good or improved thermal and / or electrical insulation. Finally, there is a need to provide a cost-effective fuel cell system.

[0004] The object of the present invention is solved by the subject matter of claim 1. The dependent claims represent preferred embodiments.

[0005] The technology disclosed here relates to a housing for a fuel cell stack. The housing comprises two end plates located at either end of the fuel cell stack. Furthermore, the housing includes two opposing side walls that connect the end plates.

[0006] In particular, the end plates are connected to one another in such a way that the fuel cells of the fuel cell stack arranged between the end plates are clamped. The housing disclosed herein further comprises a lateral connecting wall which connects the opposing side walls at least partially. The connections between the side walls, the connecting wall, and the end plates are preferably such that the connection(s) are fluid-tight.

[0007] The housing can include at least one media exchange element with media connections. The media exchange element can be integrated into one or both end plates. Alternatively or additionally, a separate media exchange element can be arranged between the end plates and the fuel cell stack.

[0008] The two end plates can each be designed as an extruded support structure. A support structure is a framework comprising several walls or members arranged at angles to each other in cross-section, connecting spaced-apart outer contours of the support structure. Such a support structure exhibits higher stiffness than a component consisting solely of the two outer walls, which rest directly on each other without any spacing.

[0009] The end plates shown here can each be designed as an extruded support structure. Designing them as extruded elements allows for cost-effective production of the end plates, which are then generally comparatively lightweight and torsionally rigid.

[0010] The housing may, in particular, include a media exchange element with media connections that do not extend transversely through the outer contours or surfaces of the end plate. This means that the media connections are not routed through the end plates to any further lines, but rather through a lateral opening in the housing.

[0011] It is particularly advantageous that the media connections are routed out on the connection side of the housing. The connection side of the housing is preferably located opposite the connecting wall. Preferably, all media connections are routed out only on the connection side. Advantageously, the connection side can also be closed off by a plate-like wall. This reveals a fully enclosed housing in which the media connections are routed out laterally only on one side.

[0012] The housing revealed here is comparatively lightweight and torsionally rigid, and can also protect the fuel cell against mechanical influences. Preferably, the housing is relatively fluid-tight.

[0013] Preferably, the opposing side walls and / or the lateral connecting wall also have a supporting structure. Advantageously, the outer walls of the supporting structure of the side walls and / or the lateral connecting wall are spaced closer together than the outer walls of the two end plates. In other words, the end plate comprises a supporting structure that is more torsionally rigid than the supporting structure of the side walls and / or the lateral connecting wall, thereby reducing the weight of the side walls and the connecting wall.

[0014] If the media element is designed separately, it is advantageous to design it as a substantially flat plate suitable for uniformly transferring the surface pressure applied by the end plates to the fuel cell stack or any other components.

[0015] Preferably, insulating layers and current collectors are arranged between the end plates. For example, an insulating layer can be integrated into a media connection or media exchange element, or the media exchange element can function as an insulating layer. Furthermore, the at least one supporting structure in the end plates, the opposing side walls, and / or the lateral connecting wall preferably comprises at least one externally accessible recess or passage. The recess or passage can be configured to accommodate at least one system component of the fuel cell system.

[0016] A system component is, for example, a part necessary for the operation of the fuel cell system. Such system components include, for instance, components located in the high-voltage section of the fuel cell. These include, for example, the Balance of Plant (BoP) components. Examples of such elements are the H2 recirculation pump and the cell voltage monitor.

[0017] Preferably, the supporting structure of the end plates, the opposing side walls, and / or the lateral connecting wall has at least one media channel. The media channel is preferably designed to establish a fluid connection between the fuel cell stack and at least one fluid line adjacent to the housing. For example, the media channels can ensure the supply of fuel, e.g., hydrogen, and oxidizing agents, e.g., atmospheric oxygen, to the fuel cell. Furthermore, coolant can flow in and out through the media channels. The media channels can be arranged in different supporting structures of various end plates or side walls.

[0018] The integration of such system components and / or such media channels into the extruded profiles enables a compact system design with comparatively stiff and lightweight components, which is also comparatively inexpensive to manufacture.

[0019] The at least one end plate can have a convex or outwardly curved outer contour in cross-section. The outer contour can be dimensioned such that it deforms during the clamping of the fuel cell stack. In particular, it can already be deformed during the welding process, especially in such a way that the outer contour rests flat on the adjacent component located between the two end plates, at least in certain areas. The adjacent component is, for example, an insulation layer or plate, a media exchange element, a fuel cell stack, etc. This convex shape of the inner outer contour, preferably as a 2D curvature, ensures that the clamping force clamping the fuel cell stack is applied uniformly, at least in certain areas, and preferably over the entire contact surface.The convex shape of the end plate allows for a particularly homogeneous contact pressure to be exerted on the fuel cell stack. This contact pressure can be applied either directly to the fuel cell stack or indirectly, for example, via a plate-shaped media exchange element. Instead of an extruded profile, a die-cast end plate would also be conceivable. However, such a plate would not be as cost-effective to manufacture as an extruded end plate.

[0020] Preferably, the opposing side walls and the end plate are welded together in such a way that the fuel cells of the fuel cell stack are clamped or braced. Preferably, the lateral connecting wall is also welded to the end plates.

[0021] Preferably, the opposing side walls and the lateral connecting wall are formed in one piece and / or in a U-shape. Such a pre-formed semi-finished product can, for example, consist of a U-shaped sheet metal part. Such a semi-finished product can further simplify manufacturing and can lead to more tightly sealed housings. Preferably, the at least one supporting structure of the end plates, the opposing side walls, and / or the lateral connecting wall is shaped to taper towards the connection areas. Such a tapered shape means that the outer walls of the supporting structure converge towards the connection area and merge into one another there. This design is particularly well suited for welding.

[0022] Preferably, a method for manufacturing the housing comprises the following steps: Providing a fuel cell stack in a press, clamping the fuel cell stack in the press, welding at least two opposing side walls to two end plates, wherein the end plates are arranged at the head and foot end of the fuel cell stack, and wherein the side walls are arranged laterally to the fuel cell stack.

[0023] In other words, it is a process for manufacturing a housing with a fuel cell stack, comprising the following steps: Providing ∘ two extruded end plates arranged at the two ends of the fuel cell stack and having a supporting structure; ∘ two opposing side walls which, when assembled, connect the end plates to each other; ∘ a lateral connecting wall which connects the opposing side walls to each other; and ∘ a fuel cell stack; clamping the fuel cell stack to the end plates (110); and welding the two opposing side walls to the lateral end plates.

[0024] After welding, the pressing force of the pressing tool can be reduced, and the housing, including the clamped fuel cell stack, can be removed. Preferably, the curved outer contour of the inner surface of the end plates deforms during the reduction of the pressing force to a planar force application to the fuel cells. The method according to the invention can further comprise the step of mounting at least one system component of the fuel cell system in at least one accessible recess or passage of a support structure.

[0025] The technology disclosed herein will now be described in more detail with reference to the figures. The figures serve only illustrative purposes and are not to be used for the restrictive interpretation of the patent claims. They show: Fig. 1 a schematic perspective view of the fuel cell housing 100 including fuel cell stack 200, Figs. 2 and 3 schematic cross-sectional views of an end plate 110, Fig. 4 a perspective view of a media exchange element 140, Fig. 5 a perspective view of an insulation plate 170, and Figs. 6 to 8 perspective views of the side walls 120 and the lateral connecting wall 130.

[0026] Fig. 1Figure 1 shows a perspective view of the housing 100 revealed here. The end plates 110 are arranged in front of the fuel cell stack 200, i.e., at the ends 210 and 220 of the fuel cell stack 200. The end plates 110 clamp together an assembly comprising the following elements: fuel cell stack 200, media exchange element 140 including media connections M, and insulating plate 170. Only one current collector 180 is visible here. However, two current collectors 180 extend from the fuel cell stack 200 on the connection side 160. The two end plates 110 are each welded to the opposite side walls 120 and the lateral connecting wall 130.

[0027] Both form-fit and force-fit connections can exist. The end plates 110 are designed here as extruded profiles. Alternatively or additionally, die-cast profiles or multi-layer panels, e.g., with aluminum foam, can also be used. Such multi-layer panels are, for example, sandwich constructions in which the two outer layers 112, 114 are also spaced apart. The die-casting process is associated with comparatively high manufacturing costs, but offers greater design freedom in the design of the components.

[0028] The operating components 300, which are integrated into the end plates, are not shown in detail. The end plates 110, the opposing side walls 120 and / or the lateral connecting wall 130 are preferably made of aluminum. Plastic is preferably used as insulation and / or sealing material.

[0029] The end plate 110 is preferably designed to be convex or bombé, at least on the inside or underside 112 (cf. Figs. 2 and 3Preferably, the end plate 110 has a curvature only in cross-section, and not in the (extrusion) longitudinal direction. Such a design of the end plate 110 facilitates its manufacture by extrusion. Since the clamping forces are essentially introduced into the end plate 110 over an entire longitudinal side via the weld seam in the connection area, such a two-dimensional curvature is also suitable for transferring the clamping forces over a surface area to the components 140, 200, 170 arranged between the end plates 110. Due to the clamping at the edge, the end plate 110 deflects under the compressive load. The degree of deflection corresponds exactly to the applied curvature, so that the end plate 110 becomes flat and can transfer the applied pressure homogeneously to the adjacent components. Adjacent components are, for example, the media exchange plate 140 or the insulating plate 170.

[0030] Instead of a media exchange plate 140, the media supply M can also be provided in the end plate(s) 110. For example, channels 155 provided in the extruded profile can be drilled or milled perpendicular to the extrusion direction. Alternatively, the end plates 110 can be manufactured using a die-casting process.

[0031] Figs. 2 and 3Figure 1 shows cross-sectional views through end plates 110. These include, for example, accessible recesses or passages 150 into which system components 300 can be integrated. Also shown is a media channel 155, suitable for conveying a fluid from a fluid line (not shown) to an element of the fuel cell stack 200. Additional sealing materials, such as plastic inserts, can be provided between the fluid and the end plate 110. The outer contours 112 and 114 are spaced apart from each other, at least in the central region, by a supporting structure. Towards the lateral ends, the outer contours 112 and 114 converge. The increased spacing in the central area of ​​the end plate 110 shown here increases the stiffness of the component 110. Since the truss or supporting structure has many recessed areas 150, 155 between the walls, the weight of the end plate 110 is comparatively low.At the same time, this installation space 150 is used for system components 300, e.g., BoP components 300. The media connections 155 do not extend transversely through the end plates 110. This means that the outer contour 114, i.e., the contour located on the side facing away from the fuel cell stack 200, is not interrupted by a media connection 155. In other words, the curved outer contour 114 is uninterrupted. Such a component 110 exhibits particularly high stiffness at a comparatively low weight. Not shown in . Fig. 2 These are any milled-out sections that connect the media channels 155 with any connections of the fuel cell stack 200.

[0032] Fig. 4 Figure 1 shows a plate-shaped design of a separate media exchange element 140. All media connections M are located on one side. This design of the housing 100 simplifies the mounting and dismounting of the housing 100 on the vehicle. Fig. 5 shows a plate-shaped insulator 170.

[0033] Fig. 6 Figure 1 shows opposing side walls 120 and a lateral connecting wall 130. The three elements 120, 130 are joined together here as a U-shaped semi-finished product. Preferably, the elements are made of aluminum or magnesium. The embodiment shown here can, for example, be manufactured from a sheet material using a bending process. Alternatively, three individual sheets could also be joined together.

[0034] Fig. 7 Figure 1 also shows a U-shaped semi-finished product in which the opposing side walls 120 have a small bend or fold at the front edge. Such a bend can further stiffen the component and facilitate its attachment to the vehicle. Otherwise, the U-shaped semi-finished product can be designed in the same way as shown in Figure 2. Fig. 6 .

[0035] Fig. 8Figure 1 shows a further embodiment of the U-shaped semi-finished product, in which at least the opposing side walls 120 have a stiffened geometry. A supporting structure is provided in each of the opposing side walls 120 for stiffening. The stiffening serves to reduce the torsional load acting on the fuel cell stack 200. Anchor points can be provided distributed across the surface of the end plates 110 or on the opposing side walls 120 to support the housing 100. Alternatively and / or additionally, anchor points can be provided in the angled area (see Figure 1). Fig. 7 ) Mounting points must be provided.

[0036] The preceding description of the present invention serves only for illustrative purposes and not to limit the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

Claims

1. Housing (100) for a fuel cell stack (200), comprising: • two end plates (110) arranged at the two ends (210, 220) of the fuel cell stack (200); • two opposite side walls (120) connecting the end plates (110) to each other; • a lateral connecting wall (130) connecting the opposite side walls (120) to each other; and • at least one media exchange element (140) with media connections (M), characterized in that • at least the two end plates (110) are each formed as an extruded support structure, and that the media connections (M) are not led transversely through the end plates (110).

2. Housing (100) according to claim 1, wherein the media connections (M) are led out of the housing (100) on the connection side (160), and wherein the connection side (160) is arranged opposite the connecting wall (130).

3. Housing (100) according to claim 1 or 2, wherein the opposite side walls (120) and / or the lateral connecting wall (130) also have a support structure.

4. Housing (100) according to one of the preceding claims, wherein the support structure has at least one accessible recess and / or passage (150), and wherein this recess and / or passage (150) is designed to accommodate at least one system component (300) of the fuel cell system.

5. Housing (100) according to one of the preceding claims, wherein the support structure has at least one media channel (155), and wherein the media channel (155) is designed to establish a fluid connection between the fuel cell stack (200) and at least one fluid line adjacent to the housing (100).

6. Housing (100) according to one of the preceding claims, wherein at least one end plate (110) has a convex outer contour (112) in cross-section, which is dimensioned in such a way that it deforms during the clamping of the fuel cell stack (200) so that the outer contour (112) rests flat on an adjacent component at least in some areas.

7. Housing (100) according to one of the preceding claims, wherein the opposite side walls (120) and the end plates (110) are welded together in such a way that the fuel cells of the fuel cell stack (200) are clamped.

8. Housing (100) according to one of the preceding claims, wherein the opposite side walls (120) and the lateral connecting wall (130) are formed in one piece and U-shaped in cross-section.

9. Housing (100) according to one of the preceding claims, wherein the support structure of the end plates (110), the opposite side walls (120) and / or the lateral connecting wall (130) tapers or taper towards the connecting areas.

10. Method for producing a housing (100) according to one of the preceding claims, comprising the steps: • Providing ∘ a fuel cell stack (200); ∘ two extruded end plates (110) arranged at the two ends of the fuel cell stack (200) and having a support structure; ∘ two opposite side walls (120) which, in the assembled state, connect the end plates (110) to each other; and ∘ a lateral connecting wall (130) connecting the opposite side walls (120) to each other; • Clamping the fuel cell stack (200); and • Welding the two opposite side walls (120) to the lateral end plates (110).