Fuel cell stack enclosure

Abstract

Disclosed is a fuel cell stack enclosure (1) for accommodating at least partly an assembled fuel cell stack, wherein the assembled fuel cell stack has at least a bottom endplate (102) and a top endplate (104) sandwiching a plurality of unit fuel cells, each unit fuel cell comprising a membrane electrode assembly and a bipolar plate, and wherein the enclosure (1) has a wall structure (2) which defines a space for accommodating the fuel cell stack, wherein the wall structure (2) is adapted to cover at least the fuel cell stack from the bottom endplate (102) to the top endplate (104) and further has a bottom edge (12) which is adapted to be mounted to a bottom cover plate (9) for the fuel cell stack enclosure (1), particularly the bottom endplate (102) of the fuel cell stack, and a top edge (14) which is adapted to be mounted to a top cover plate (8) for the fuel cell stack enclosure (1), wherein the wall structure (2) at least one protruding rib (20).

Description

[0001] Fuel cell stack enclosure

[0002] Description:

[0003] Technical field of the invention

[0004] The present invention relates to fuel cell stack enclosure according to the preamble of claim 1.

[0005] Technical background

[0006] For protecting the fuel cell stack from the environment as well as persons from touching the fuel cell stack it is known to accommodate the fuel cell stack in a fuel cell stack housing.

[0007] Since in the recent years, the fuel cell stacks have increased in size, but shall at the same time be as light-weighted as possible, the housings became lighter, but also prone to damage, particularly in mobile applications.

[0008] It is therefore object of the present invention, to provide a fuel cell stack housing which is both light-weighted and has a high stability and rigidity.

[0009] General description of the invention

[0010] This object is solved by a fuel cell stack enclosure according to claim 1.

[0011] In the following a fuel cell stack enclosure for accommodating at least partly an assembled fuel cell stack is disclosed, wherein the assembled fuel cell stack has at least a bottom endplate and a top endplate sandwiching a plurality of unit fuel cells, each unit fuel cell comprising a membrane electrode assembly and a bipolar plate.

[0012] Thereby, it should be noted that “bottom” and “top” are used in this application to simplify the description of a fuel cell stack and / or its components, and / or of orientations in relation to the fuel cell stack (vertical stacking direction). However, theentire application is also applicable to a fuel cell stack, where “bottom” and “top” endplate are arranged at the sides of the fuel cell stack (horizontal stacking direction). Thus, the wording “bottom endplate” refers e.g. to an endplate which is connectable to reactant providing components, such as ducts, whereas the word “top endplate” describes e.g. the endplate of the stack which is “only” closing the reactant manifolds provided by the stacked unit fuel cells.

[0013] Further, the suggested fuel cell stack enclosure has a wall structure which defines a space for accommodating the fuel cell stack, wherein the wall structure is adapted to cover at least the fuel cell stack from the bottom endplate to the top endplate and further has a bottom edge which is adapted to be mounted to a bottom cover plate for the fuel cell stack enclosure, particularly the bottom endplate of the fuel cell stack, and a top edge which is adapted to be mounted to a top cover plate for the fuel cell stack enclosure.

[0014] Thereby, “bottom” and “top” endplate are defined in relation to the fuel cell stack, particularly in relation to a stacking direction of the unit fuel cells. With other word, in case the unit fuel cells are arranged so that the faces of the plates extend horizontally, the fuel cell stack has a vertical stacking direction and the “bottom” and “top” endplates are also arranged at the bottom / top in a gravitational view. However, in case the faces of the unit fuel cell plates extend vertically, which means that the fuel cell stack has a horizontal stacking direction, the “bottom” and “top” endplate are arranged at the sides in relation to gravity.

[0015] For providing an enclosure having a high rigidity but being still light-weighted, it is suggested that the wall structure has at least one protruding rib.

[0016] Thereby, the protruding rib increases the stability of the wall structure and allows for reducing the wall thickness in the parts which are not formed by the protruding rib. The protruding rib itself may be formed by a thickening of the wall thickness in the respective area.Even if the protruding ribs could be formed by a thickening of the wall thickness in the respective area, it is preferred that the wall thickness remains the same for the entire enclosure. Consequently, an embodiment is preferred, wherein the wall structure has a corrugated structure with the at least one protruding rib, protruding from a face of the respective wall, which forms a recess on the opposite face.

[0017] Thereby, the protruding rib increases the stability and rigidity of the wall structure and allows for reducing a wall thickness of the wall structure itself which in turn allows for reducing the overall weight of the enclosure.

[0018] The enclosure itself may have a shape which mirrors the shape of the fuel cell stack. E.g. a cuboid shaped fuel cell stack would be enclosed by a cuboid shaped enclosure with e.g. four side walls, whereas a cylindrical fuel cell stack would be enclosed by a cylindrical shaped enclosure.

[0019] According to a preferred embodiment, the fuel cell stack has a cuboid shape and the enclosure has also an cuboid shape, with at least four side walls forming the wall structure.

[0020] According to a preferred embodiment, the at least one protruding rib extends from the bottom edge to the top edge of the wall structure. Even if it is possible that the rib extends only partly along the wall structure, a protruding rib which extends from bottom edge to top edge provides a maximalized stability.

[0021] According to a further preferred embodiment, the protruding rib is extending only partly along the wall structure. For example, the protruding rib may be formed with a distance to the bottom edge and / or top edge of the enclosure. This also allows for increased stability and rigidity.

[0022] It is further preferred that an orientation of the protruding rib in relation to the enclosure is adapted to increase stability and rigidity in certain areas. This also means that the at least one protruding rib may be angled in relation to the bottom edge / top edge and / or to a vertical or horizontal direction. In case there is more thanone rib it is also possible that the ribs have different orientation angles and / or are angled to each other.

[0023] According to a further preferred embodiment, the enclosure has at least a first protruding rib and a second protruding rib which are separate from each other by a recess. It is further preferred that the enclosure has a plurality of ribs and intermediate recesses, so that the wall structure has in an alternating arrangement of ribs and recesses.

[0024] Advantageously, the plurality of ribs and recesses is equally distributed over the wall structure. This increases the rigidity and stability of the entire wall structure.

[0025] Alternatively, it can be also preferred to arrange the ribs and recesses only in an area of the wall structure in which a high load impact is expected.

[0026] Alternatively, it can be also preferred to arrange a different number ribs and recesses in different areas of the wall structure. This allows for an area adapted arrangement of the ribs in accordance with expected load impacts, so that e.g. high loaded areas have a different number of ribs than less loaded areas.

[0027] According to a further preferred embodiment the first protruding rib and the second protruding rib have a different width. This also increases stability and rigidity.

[0028] Thereby, it is further preferred to have plurality of ribs having a small width and a plurality of ribs having a large width. Advantageously, the small width ribs and the large width ribs are arranged alternatingly. However, it is also possible that the small width ribs are arranged in a different area, e.g. on a different side wall of the enclosure, than the large width ribs. This allows for an area adapted arrangement of the ribs in accordance with expected load impacts, so that e.g. high loaded areas have different designed ribs than less loaded areas.

[0029] It goes without saying that it might be preferable that each rib may have a different width or that there is a plurality of groups of ribs having the same size, which may bearranged at the enclosure at the desired location depending e.g. on the expected load.

[0030] According to a further preferred embodiment, the at least one protruding rib has at least a front-face, and / or a first side-face and / or a second side-face. Furthermore, also the recess may have a recess-face, wherein at least one of the front-face, sidefaces and / or recess-face is designed as flat plane. This allows a space saving design of the enclosure as the flat planes are reducing the overall protrusion of the protruding ribs and thereby the overall width and / or length of the enclosure even if the enclosure has protruding rib(s).

[0031] According to a further preferred embodiment, the wall structure is slanted so that an area surrounded by the bottom edge is larger than an area surrounded by the top edge. With other words, the wall structure is slanting from the bottom edge to the top edge. This allows to cast the enclosure in a mold, as due to the slanted design the enclosure may be easily removed from the mold.

[0032] For providing the slanted wall structure, according to a further preferred embodiment, the at least one protruding rib has at least a front-face with a front-face inclination, and / or a first side-face with a first side-face inclination and / or a second side-face with a second side-face inclination, wherein preferably the front-face inclination and / or the side-face inclinations are different. Thereby, it is further preferred that the first sideface inclination and the second side-face inclination are equal. This has the advantage that an area provided at the top of the rib is large enough so that a fastening element may be arranged in this area.

[0033] According to a further preferred embodiment, the recess has a recess-face having a recess-face inclination, wherein preferably the recess-face inclination is different from the front-face inclination and / or the side-face inclinations. This has the advantage that an area provided at the top edge, particularly at the top of the protruding rib is large enough so that a fastening element may be arranged in this area. At the same time this design also ensures that there is sufficient space for a fastening element at thebottom edge to be arranged in the recess. Thereby, the overall dimensions of the stack may be designed to be as small as possible.

[0034] According to a further preferred embodiment, the front-face inclination is between 0.5° and 5°, preferably 1° and 2°, and / or the recess-face inclination is between 0.1° and 2°, preferably between 0.5° and 1° and / or the first and / or second side-face inclination is between 0° and 1°, preferably 0° and 0.5°, wherein each inclination is defined as deviation from a perpendicular extension of the respective face.

[0035] These inclination / s allow for an enclosure having a rib structure for extra stability with a maximized space for the cover plate. The inclination is further advantageous for casting the enclosure in a mold, as due to the slanted design the enclosure may be easily removed from the mold. Further, the above mentioned inclination results in an enclosure having a maximized inner volume but minimalized overall dimensions.

[0036] According to a further preferred embodiment, a width of the at least one protruding rib is decreasing from the bottom edge to the top edge. Additionally or alternatively, a depth of the at least one protruding rib is decreasing from the bottom edge to the top edge. This allows for an enclosure having a rib structure for extra stability with a maximized space for the cover plate. Further, this rib design may result in an enclosure having a maximized inner volume but minimalized overall dimensions.

[0037] According to a further preferred embodiment, the bottom edge and / or the top edge of the enclosure has a flange extending substantially in parallel to the bottom cover plate and / or in parallel to the top cover plate for fastening the wall structure to the bottom cover plate and / or to the top cover plate, wherein the flange has at least one fastening component which is adapted to interact with a fastening element for fastening the wall structure to the respective cover plate. This top and / or bottom flange provides a simple possibility for attaching top and bottom cover plate respectively.

[0038] Thereby it is further preferred that the fuel cell stack enclosure has at least a first protruding rib and a second protruding rib, which are separate from each other by arecess, and wherein the fasting component of the bottom flange is arrange in an area of the recess and / or wherein the fastening component of the top flange is arranged in an area of the protruding rib. This allows for an enclosure having a rib structure for extra stability with a maximized inner volume but minimalized overall dimensions.

[0039] Preferably, the enclosure is made from a fiber reinforced plastic material, particularly from glass fibers embedded in an epoxy resin matrix.

[0040] It goes without saying that other plastic materials and reinforcement fibers may be used. As further reinforcement fibers, Carbon fibers, Aramid fibers, Cellulose fibers and / or Basalt fibers can be used. Besides an epoxy resin matrix, or other thermosets such as phenolic and polyester, it is also possible and may be preferred to use a thermoplastic material in certain embodiments, such as PEEK, PEK, PI, PPS, PEI, POM, PA, PAI or PBL

[0041] Further preferred embodiments are defined in the dependent claims as well as in the description and the figures. Thereby, elements described or shown in combination with other elements may be present alone or in combination with other elements without departing from the scope of protection.

[0042] Brief description of the drawings

[0043] In the following, preferred embodiments of the invention are described in relation to the drawings, wherein the drawings are exemplarily only, and are not intended to limit the scope of protection. The scope of protection is defined by the accompanied claims, only.

[0044] The figures show:

[0045] Fig. 1 : a schematic view of a preferred embodiment of the enclosure in a closed state;

[0046] Fig. 2: a schematic explosive view of the enclosure;

[0047] Fig. 3: a schematic view of the enclosure without top cover plate

[0048] Fig. 4: a schematic view of the side walls of the enclosure

[0049] Fig. 5: a schematic top view onto the wall structureFig. 6: a detailed view of the wall structure depicted in Fig. 5; and Fig. 7: a detailed view of the wall structure depicted in Fig. 5.

[0050] Detailed description of the invention

[0051] In the following same or similar functioning elements are indicated with the same reference numerals.

[0052] Figs. 1 to 7 depict various illustrative views of a fuel cell stack enclosure 1 for fuel cell stack 100.

[0053] Figure 1 illustrates a schematic perspective view of an enclosure 1 having a wall structure 2 with front wall 4, rear wall 5 and two side walls 6a; 6b. Further, the enclosure 1 is closed with a top cover 8 and a bottom cover 9, which are fastened with fastening elements 18, and 19 to the top cover plate 8 and the bottom cover plate 9, respectively.

[0054] As illustrated in Figs. 2 and 3, the enclosure 1 defines a space 10 for accommodating a cuboid fuel cell stack 100. The fuel cell stack 100 has a top endplate 104 (see Fig.

[0055] 3) and a bottom endplate 102 (see Fig. 2), which are sandwiching a plurality of unit fuel cells 106 comprising at least a bipolar plate 107 and a membrane electrode assembly 108. Thereby, as is illustrated in Fig. 2, the bottom cover plate 8 and the endplate 102 of the fuel cell stack may be designed as integral part. It is further illustrated that the walls 4; 5, 6 cover the fuel cell stack 100, so that the entire fuel cell stack 100 is accommodated within the enclosure 1.

[0056] The fuel cell stack enclosure 1 further has a bottom edge 12 and a top edge 14, wherein bottom edge 12 and top edge 14 merge into flanges 13 and 15 (see Figs. 2 and 3). The flanges 13 and 15 are equipped with the fastening components 18, 19 (see Fig. 1 and 3) with which the enclosure 1 may be fastened to the bottom cover plate 9 and the top cover plate 8 for closing the enclosure 1 (see also Figs.1 and 3).The enclosure 1 may be made from a fiber reinforced plastic material, particularly from glass fibers embedded in an epoxy resin matrix for providing a light-weight enclosure for the fuel cell stack 100.

[0057] As can be further seen from the Figures and particularly from Fig. 4a and 4b, illustrating a view onto the front resp. rear wall 4; 5 (see Fig. 4a) and one of the side walls 6a, 6b (Fig. 4b), the wall structure 2 has at an outside-face 24 of the enclosure 1 a plurality of protruding ribs 20, which are separated by recesses 22.

[0058] Even if the protruding ribs 20 could be formed by a thickening of the wall thickness in the respective area, it is preferred that the wall thickness remains the same for the entire enclosure. Forthat, the recesses 22 form protruding ribs 21 at an inside-face 25 of the enclosure 1, which in turn are separated by recesses 23, which are formed by the protruding ribs 22. This design results in a corrugated wall structure 2, which increases the stability and rigidity of the walls 4-6 and allows for a uniform wall thickness of walls 4-6.

[0059] As can be further seen, the protruding ribs 20; 21 and recesses 22; 23 extend from the bottom edge 12 to the top edge 14 of the wall structure 2 so that a maximalized stability is provided.

[0060] As can be seen in Fig. 4, the wall structure 2 as such is slanted from the bottom edge 12 to the top edge 14 by an inclination angle a. This also means that an area surrounded by the bottom edge 12 is larger than an area surrounded by the top edge 14.

[0061] As is illustrated in Figs. 5 to 7, for providing the slanted and corrugates wall structure 2, the protruding ribs 20 have at least a front-face 30 with a front-face inclination 31, and a first side-face 32 with a first side-face inclination 33 and a second side-face 34 with a second side-face inclination 35. Further the recesses 22 have a recess-face 36 having a recess-face inclination 37. This design results in the illustrated wall structure 2 of Figs 1 to 7.For providing sufficient space at the top flange 15, which is large enough so that the fastening element may 18 be arranged in this area, the front-face inclination 31 and the side-face inclinations 33, 35 are different, as can be seen in Fig. 6 and 7. Thereby, it is further preferred that the first side-face inclination 33 and the second side-face inclination 35 are equal. Further, also the recess-face inclination 37 is different from the front-face inclination 31 and / or the side-face inclinations 33; 35. Preferably, the front-face inclination is between 1° and 2°, the recess-face inclination 37 is between 0.5° and 1° and the first and second side-face inclination is between 0° and 0.5°.

[0062] It is further illustrated that the front face 30, the side faces 32, 34 and the recess face 36 are designed as flat planes, which also provides the space saving design of the enclosure 2.

[0063] In the illustrated embodiment of Figs. 1 to 7, the protruding ribs 20 of front wall 4 and rear wall 5 have, at the same height, the same width. However, compared to the sides walls 6a, 6b, the protruding ribs 20 have a different width at said same. Here, the protruding ribs 20’ of the side walls 6 are smaller than the protruding ribs 20 of the front 4 resp. rear wall 6. This allows for an enclosure having the same number of protruding ribs 20; 20’ at each side even if the walls 4, 5 and 6 itself differ in size. This also increases stability and rigidity. However, it might be also advantageous that the small width ribs 20’ and the large width ribs 20 are arranged alternatingly at the same wall or the ribs have the same size at all walls.

[0064] As illustrated in the Figs. 4 and 7, a width W of the at least one protruding rib 20 is decreasing from the bottom edge 12 (W12) to the top edge 14 (W14). At the same time, the width W’ of the recess 22 is increasing from bottom edge 12 (W’12) to top edge 14 (W’14). Additionally or alternatively, also a depth D of the at least one protruding rib 20 may be decreasing from the bottom edge 12 (D12) to the top edge 14 (D14).

[0065] The corrugated wall structure 2 as depicted in the Figs. 1 to 7 further allows that the fasting elements 18; 19 of the bottom 13 and top flange 15, respectively, may be arranged in a zig-zag pattern Z as is in detail depicted in Fig. 7. With other words, thefastening elements 18; 19 may be arranged in such a way, that the fastening elements 19 at the bottom flange 13 are arranged in the area of the recess 22, whereas the fasting elements 18 of the top flange 15 are arranged in the area of the protruding rib 20. This allows for an enclosure 1 having a rib structure for extra stability with a maximized inner volume.Reference numerals

[0066] 1 enclosure

[0067] 2 wall structure

[0068] 4 front wall

[0069] 5 rear wall

[0070] 6 side wall

[0071] 8 top cover plate

[0072] 9 bottom cover plate

[0073] 10 inner space

[0074] 12 bottom edge

[0075] 13 bottom flange

[0076] 14 top edge

[0077] 15 top flange

[0078] 18;19 fastenings

[0079] 20 protruding rib (outside)

[0080] 21 recess (inside)

[0081] 22 recess (outside)

[0082] 23 protruding rib (Inside)

[0083] 24 outside face

[0084] 25 insides face

[0085] 30 front face

[0086] 31 front face inclination

[0087] 32;34 side face

[0088] 33;35 side face inclination

[0089] 36 recess face

[0090] 37 recess face inclination

[0091] 100 fuel cell stack

[0092] 102 bottom endplate

[0093] 104 top endplate

[0094] 106 unit fuel cell

[0095] 107 bipolar plate

[0096] 108 membrane electrode assembly

Claims

Fuel cell stack enclosureClaims:

1. Fuel cell stack enclosure (1) for accommodating at least partly an assembled fuel cell stack (100), wherein the assembled fuel cell stack (100) has at least a bottom endplate (102) and a top endplate (104) sandwiching a plurality of unit fuel cells (106), each unit fuel cell (106) comprising a membrane electrode assembly (108) and a bipolar plate (107), and wherein the enclosure (1) has a wall structure (2) which defines a space for accommodating the fuel cell stack (100), wherein the wall structure (2) is adapted to cover at least the fuel cell stack (100) from the bottom endplate (102) to the top endplate (104) and further has a bottom edge (12) which is adapted to be mounted to a bottom cover plate (9) for the fuel cell stack enclosure (1), particularly the bottom endplate (102) of the fuel cell stack (100), and a top edge (14) which is adapted to be mounted to a top cover plate (8) for the fuel cell stack enclosure (1) characterized in that the wall structure (2) has at least one protruding rib (20).

2. Fuel cell stack enclosure (1) according to claim 1, wherein the wall structure (2) has a corrugated structure, wherein at least one protruding rib (20) protrudes from an outside (24) of the wall structure (2) and forms a recess (22) on the inside (25) of the wall structure (2), and / or wherein at least one protruding rib (20) protrudes from an inside (25) of the wall structure (2) and forms a recess (22) on the outside (24) of the wall structure (2).

3. Fuel cell stack enclosure (1) according to claim 1 or 2, wherein the at least one protruding rib (20) extends from the bottom edge (12) to the top edge (14) of the wall structure (2).

4. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein the enclosure (1) has at least a first protruding rib (20) and a second protruding rib (20) which are separate from each other by a recess (22).

5. Fuel cell stack enclosure (1) according to claim 4, wherein the first protruding rib (20) and the second protruding rib (20) have a different width.

6. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein the at least one protruding rib (20) has at least a front-face (30), and / or a first side-face (32; 34) and / or a second side-face (32; 34) and / or wherein the recess (22) has a recess-face (36), wherein at least one of the front-face (30), side-faces (32; 34) and / or recess-face (36) is designed as flat plane.

7. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein the wall structure (2) is slanted so that an area surrounded by the bottom edge (12) is larger than an area surrounded by the top edge (14).

8. Fuel cell stack enclosure (1) according to claim 6 or 7, wherein the front-face (30) has a front-face inclination (31), and / or the first side-face (32; 34) has a first side-face inclination (33; 35) and / or the second side-face (32; 34) has a second side-face inclination (33; 35), wherein preferably the front-face inclination (31) and the side-face inclinations (33; 35) are different.

9. Fuel cell stack enclosure (1 ) according to any one of claims 6 to 8, wherein the recess (22) has a recess-face (36) having a recess-face inclination (37), wherein preferably the recess-face inclination (37) is different from the frontface inclination (31) and / or the side-face inclinations (33; 35).

10. Fuel cell stack enclosure (1) according to claim 8 or 9, wherein the front-face inclination (31) is between 1° and 2°, and / or the recess-face inclination (37) is between 0.5° and 1° and / or the first and / or second side-face inclination (33;35) is between 0° and 0.5°, wherein each inclination is defined as deviation from a perpendicular extension of the respective face.

11. Fuel cell stack enclosure (1 ) according to any one of the preceding claims, wherein a width (W) of the at least one protruding rib (20) is decreasing from the bottom edge (12) to the top edge (14).

12. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein a depth (D) of the at least one protruding rib (20) is decreasing from the bottom edge (12) to the top edge (14).

13. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein the bottom edge (12) and / or the top edge (14) has a flange (13; 15) extending substantially in parallel to the bottom cover plate (9) and / or in parallel to the top cover plate (8) for fastening the wall structure (2) to the bottom cover plate (9) and / or to the top cover plate (8), wherein the flange (13; 15) has at least one fastening component, which is adapted to interact with a fastening element (18; 19) for fastening the wall structure (2) to the respective cover plate (8; 9).

14. Fuel cell stack enclosure (1) according to claim 13, wherein the fuel cell stack enclosure (1) has at least a first protruding rib (20) and a second protruding rib (20) which are separate from each other by a recess (22), and wherein the fasting component and / or the fastening element (19) of the bottom flange (13) is arranged in an area of the recess (22) and / or wherein the fastening component and / or the fastening element (18) of the top flange (15) is arranged in an area of the protruding rib (20).

15. Fuel cell stack enclosure (1) according to any one of the preceding claims, wherein the enclosure (1) is made from a fiber reinforced plastic material, particularly from glass fibers embedded in an epoxy resin matrix.

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