End plate, cell stack and a method for manufacturing an end plate

Abstract

The invention relates to an end plate (10) for a cell stack (72) with features of claim 1, a cell stack (72) with at least one such end plate (10) and a method for producing such an end plate (10).

Description

[0001] The invention relates to an end plate for a cell stack having the features of claim 1, a cell stack having the features of claim 15 and a method for producing an end plate having the features of claim 16.

[0002] A cell stack consists of several stacked plates (cell plates) arranged between two end plates. The end plates must ensure electrical insulation between the stacked plates and be as rigid as possible to prevent the plates from breaking due to possible deformation caused by the media pressure and sealing forces.

[0003] End plates made entirely of plastic can be used for this purpose. The disadvantage of such end plates is that they are relatively thick in order to achieve the required rigidity. Alternatively, overmolded end plates could be used, which are made of metal with a plastic overmold. The desired rigidity is achieved by the metal and the required electrical insulation by the plastic overmold. The disadvantage of this is that strong stresses can arise, particularly in the area of ​​media passages, which can lead to a risk of the end plates breaking and thus to leaks in the cell stack. The stresses can arise due to thermally induced different linear expansion between metal and plastic. The stresses can also arise from shrinkage of the plastic overmold after the metal has been overmolded.

[0004] DE 20 2022 104 313 U1 and CN 2 01 117 728 Y each disclose an end plate for a cell stack having features of claim 1.

[0005] It is an object of the present application to provide an end plate for a cell stack, a cell stack and a method for producing an end plate, wherein the above disadvantages are eliminated.

[0006] This object is achieved by an end plate for a cell stack having the features of claim 1. The end plate comprises a first component made of plastic and a second component made of metal. The second component made of metal is, in particular, a component formed separately from the first component. The end plate comprises at least one connecting device. The first component and the second component are positioned on top of one another and positively connected to one another by means of the connecting device. The first and the second component are, in particular, positioned on top of one another with their respective flat sides and positively connected to one another by means of the connecting device.

[0007] The first component can be designed as a first plate part. The second component can be designed as a second plate part. The cell stack can be designed, for example, as a fuel cell stack. The first component serves as a plastic support for electrical insulation (plastic insulator). The second component, in particular as a metallic carrier plate, serves to stabilize (rigidity) the end plate.

[0008] The first component and the second component are (firmly) connected to one another in particular in a thickness direction. In this case, a thickness direction refers to the direction along which the thickness (the smallest extension of the end plate) of the first or second component runs. The thickness direction can be oriented orthogonally to the flat side of the components or plate parts (normal vector). The end plate can be designed as a hybrid end plate (metal-plastic). This makes it possible to create an end plate that fulfills the required rigidity on the one hand and the electrically insulating function on the other. In addition, improved flatness can be achieved, in particular for the use of (easily breakable) graphite bipolar plates.

[0009] According to a further development of the end plate, the first component and / or the second component can each be formed integrally and separately. In particular, the first and second components are not formed as a (combined) common injection-molded component. In particular, the first component or the first plate part is not "injected" onto the second component or the second plate part (no overmolding or overmolding). Rather, the two components are formed separately from one another and are only positively connected to one another by the connecting device. This allows the disadvantages of an overmolded end plate to be avoided using simple design means.

[0010] According to the invention, the first component has at least one extension with a shaft section and a head section. The extension can be mushroom-shaped (mushroom-like). The second component has at least one first opening. The extension projects with the shaft section through the first opening and engages behind the first opening or its edge with the head section. The extension and the first opening are part of the connecting device. The extension and the first opening can be designed as a riveted connection (extension as a rivet). With a riveted connection, the positive connection between the first component and the second component cannot be released again without causing damage. The extension and the first opening can alternatively be designed as a clip connection (extension as a clip element or locking lug).In a clip connection, the form - fit connection between the first component and the second component can in particular be released without destruction. With this, the connecting device can be realized by simple means.

[0011] According to a further development of the end plate, the shaft section of the extension can have an outer surface (or an outer circumference). The shaft section of the extension can be arranged at a distance (play - provided) from the second component, in particular from an inner surface (or an inner circumference) of the first opening, with its outer surface (or with its outer circumference). Thereby, a play between the first component and the second component, in particular in a longitudinal and / or transverse direction, can be implemented by simple means and thus the shrinkage or length - expansion problem can be solved.

[0012] Here, the longitudinal direction and the transverse direction are orthogonal to each other and each is oriented orthogonally to the thickness direction. The longitudinal direction is in particular oriented along the length of the first or the second component. The transverse direction is in particular oriented along the width of the first or the second component. The thickness direction is in particular oriented along the thickness of the first or the second component.

[0013] To compensate for the different length expansions of the different materials (plastic and metal) and to avoid the resulting stresses (especially in the plastic), the first component may have a clearance in the longitudinal direction and the transverse direction relative to the second component. In particular, there may be no clearance between the first component and the second component along the thickness direction.

[0014] According to a further development of the end plate, the head portion of the extension can be formed by thermal forming ("forming by heat input"). In other words, the head portion of the extension can be produced by thermal deformation. In particular, the head portion of the extension can be produced by "hot riveting" or thermally formed into a rivet head. This allows the head portion of the extension to be formed using simple means, thus creating a positive connection between the extension and the first opening.

[0015] According to a further development of the end plate, the first component can have at least one screw-in opening. The second component can have at least a second opening. The end plate can comprise at least one screw. The screw can be screwed through the second opening into the screw-in opening. The screw-in opening, the second opening, and the screw can be components of the connecting device. The screw-in opening can be designed as a blind hole. This allows the connecting device to be realized using proven means.

[0016] According to a further development of the end plate, the screw-in opening can be arranged on and / or in a pin-like elevation of the first component. It is also conceivable for the elevation to be designed as a platform. The pin-like elevation can be part of the connecting device. This allows the screw to be secured in the screw-in opening with sufficient stability.

[0017] According to a further development of the end plate, the second component can have at least one recess into which the peg-like protrusion is received (when the first and second components are arranged one above the other). The recess can be part of the connecting device. This allows for the stable fastening of the screw in the screw-in opening using simple means, while at the same time the thickness of the end plate (or of the first and second components) does not increase or can be kept constant.

[0018] According to a further development of the end plate, the peg-like elevation can have an outer circumference (or a radial outer surface). The peg-like elevation can be arranged with its outer circumference at a distance from the second component, in particular from an inner circumference (or a radial inner surface) of the recess. This allows for simple means to implement a clearance between the peg-like elevation and the second component or the recess in the longitudinal and / or transverse direction.

[0019] According to a further development of the end plate, the screw can have a shaft portion with an outer surface (or an outer circumference). The shaft portion can be arranged with its outer surface (or its outer circumference) at a distance from the second component, in particular from an inner surface (or an inner circumference) of the second opening. This allows simple means to implement a play between the shaft portion of the screw and the second component or the second opening in the longitudinal and / or transverse direction.

[0020] According to a further development of the end plate, a countersink of the second component can be connected to the first opening and / or the second opening. The countersink can be arranged on a side of the second component facing away from the first component (flat side). The countersink can be enlarged relative to the first opening and / or the second opening (radially or in diameter). The countersink can be part of the connecting device. The countersink can be dimensioned such that the head section of the extension or a screw head of the screw is received in the respective countersink. In particular, the head section of the extension or the screw head of the screw does not protrude (along the thickness direction) from the second component or the respective countersink. The connecting device can thus be implemented using simple means, wherein at the same time the thickness of the end plate does not increase or can be kept the same.

[0021] According to a further development of the end plate, an outer circumference of the head portion of the extension and / or an outer circumference of a screw head of the screw can each be smaller than an inner circumference of the countersunk hole. This allows for simple means to create a clearance between the head portion of the extension or the screw head of the screw and the respective countersunk hole in the longitudinal and / or transverse directions.

[0022] According to a further development of the end plate, the first component can have at least one continuous channel. The channel can be delimited on the outside by a channel wall and can be open at the end (towards both of its ends). The second component can have at least one third opening. The channel wall of the channel can protrude into the third opening. The channel wall can be arranged at a distance (with play) from the third opening. The first, the second and / or the third opening can each be designed as a through-opening. In this way, play between the channel and the third opening in the longitudinal and / or transverse direction can be achieved using simple means.

[0023] According to a further development of the end plate, the channel can have a first opening (or a first end) and a second opening (or a second end). At least one groove for arranging a seal can be arranged on the front side of the first opening and / or the second opening. The groove can be arranged in the channel wall. This allows the channel to be sealed using simple means.

[0024] The above object is achieved by a cell stack having the features of claim 14. The cell stack comprises at least two or more bipolar plates stacked on top of one another and at least one end plate according to the above embodiments. The bipolar plates can be made of graphite and / or carbon. The cell stack comprises, in particular, two end plates arranged at opposite ends of the cell stack. In other words, the bipolar plates are arranged, in particular, between two end plates.

[0025] Regarding the advantages that can be achieved, please refer to the relevant explanations regarding the end plate. The measures described in connection with the end plate and / or those explained below can be used to further configure the cell stack.

[0026] The above object is achieved by a method for producing an end plate for a cell stack according to the above embodiments with the features of claim 15. The method comprises the steps: Manufacturing and / or providing the first plastic component.

[0027] Manufacturing and / or providing the second component made of metal.

[0028] Positioning the two components on top of each other and positively connecting the first component with the second component.

[0029] Regarding the advantages that can be achieved, reference is made to the relevant comments on the end plate. The measures described in connection with the end plate and / or those explained below can be used to further refine the process.

[0030] According to a further development of the method, the positive connection of the first component to the second component can be achieved by screwing, riveting (in particular, hot riveting), clipping, and / or deformation through heat input. This allows a positive connection between the first component and the second component to be achieved using simple means.

[0031] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show: Fig. 1 is a perspective view of an end plate according to a first embodiment; Fig. 2 a section of a perspective view of a first component of the end plate according to Fig. 1; Fig. 3 a cross section through a connecting device of the end plate according to Fig. 1; Fig. 4 a cross section through a channel of the end plate according to Fig. 1; Fig. 5 a perspective view of the end plate according to a second embodiment; Fig. 6 a section of a perspective view of the first component of the end plate according to Fig. 5; Fig. 7 a cross section through a connecting device of the end plate according to Fig. 5; and Fig. 8 a schematic side view of a cell stack.

[0032] In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.

[0033] Fig. Figure 1 shows a perspective view of an end plate 10 according to a first embodiment. This is an end plate 10 for a cell stack 72 (cf. Fig. 8).

[0034] The end plate 10 comprises a first component 12 made of plastic and a second component 14 made of metal (cf. Fig. 1). The end plate 10 comprises at least one connecting device 16. In the present example, the end plate 10 comprises 32 connecting devices 16, each of which is arranged in rows of four connecting devices 16 distributed across the end plate 10. The first component 12 and the second component 14 are positioned one above the other and positively connected to one another by means of the connecting device 16, in this case by means of the connecting devices 16.

[0035] In this case, the end plate 10 has a length that extends along a longitudinal direction 11. In this case, the end plate 10 has a width that extends along a transverse direction 13. In this case, the end plate 10 has a thickness that extends along a thickness direction 15. In this case, the longitudinal direction 11, the transverse direction 13, and the thickness direction 15 are each oriented orthogonally to one another.

[0036] Fig. 2 shows a section of a perspective view of the first component 12 of the end plate 10 according to Fig. 1.

[0037] In this case, the first component 12 and the second component 14 are each formed as a single piece and separately. In particular, the first component 12 and the second component 14 are not formed as a single injection-molded part.

[0038] Fig. 3 shows a cross section through one of the connecting devices 16 of the end plate 10 according to Fig. 1.

[0039] The first component 12 in the present case has at least one extension 18. The extension 18 is mushroom-shaped in the present case. The extension 18 has a shaft section 20 and a head section 22. The second component 14 in the present case has at least one first opening 24. The extension 18 protrudes with the shaft section 20 through the first opening 24 and engages behind the first opening 24 with the head section 22. The extension 18 and the first opening 24 are in the present case part of the connecting device 16. Accordingly, the first component 12 has a total of 32 extensions 18 and the second component 14 has a total of 32 first openings 24.

[0040] The shaft portion 20 of the extension 18 has an outer surface 26 (or an outer circumference). The shaft portion 20 is arranged with the outer surface 26 (or outer circumference) at a distance from the second component 14. In this case, the shaft portion 20 of the extension 18 is arranged with its outer surface 26 (or outer circumference) at a distance from an inner surface 28 of the first opening 24. This allows for play to be implemented between the shaft portion 20 and the second component 14, in particular the first opening 24, in the longitudinal direction 11 and the transverse direction 13.

[0041] The head portion 22 of the extension 18 is formed in this case by deformation through heat input. In other words, the head portion 22 of the extension 18 corresponds to a rivet head formed by hot riveting or thermal forming.

[0042] In the present case, the first component 12 and the second component 14, in the connected state, have no play along the thickness direction 15. In other words, there is no distance between the first component and the second component 14 along the thickness direction 15.

[0043] The second component 14 has 32 recesses 50 in the present case. The recesses 50 each adjoin the respective first opening 24. The recesses 50 are arranged on a side (flat side) of the second component 14 facing away from the first component 12 (see FIG. Fig. 3). The recesses 50 are each enlarged relative to the respective first opening 24. In other words, the diameter of the recesses 50 is each larger than the diameter of the respective first openings 24. The recesses 50 are presently part of the connecting devices 16.

[0044] The 32 connecting devices 16 of the end plate 10 according to Fig. 1 are identically designed in the present case. It is also conceivable that at least two of the connecting devices 16 may be designed differently.

[0045] An outer circumference 52 (or radial outer surface) of the respective head section 22 of the extension 18 is in the present case smaller than an inner circumference 58 (or radial inner surface) of the respective countersink 50. This ensures a clearance between the first component 12 and the second component 14 and in particular between the head sections 22 of the extensions 18 and the countersinks 50 in the longitudinal direction 11 and the transverse direction 13.

[0046] Fig. 4 shows a cross section through a channel 60 of the end plate 10 according to Fig. 1.

[0047] The first component 12 has six (cf. Fig. 1) has continuous channels 60. Each of the channels 60 has a channel wall 62 that defines the respective channel 60 to the outside. The channels 60 are open at the ends. The second component 14 has six third openings 64 in this case (cf. Fig. 1), into which the respective channel walls 62 of the channels 60 protrude. Each channel wall 62 is arranged at a distance from the respective third opening 64. This ensures clearance between the first component 12 and the second component 14, and in particular between the channels 60 (or the channel walls 62) and the third openings 64 in the longitudinal direction 11 and the transverse direction 13.

[0048] Each of the channels 60 can have a first opening 66 and a second opening 68. A groove 70 for arranging a seal can be formed on the end face of the first opening 66 and the second opening 68, in this case in the respective channel wall 62.

[0049] Fig. Figure 5 shows a perspective view of the end plate 10 according to a second embodiment. The second embodiment differs from the first, in the Fig. 1 to 4, by differently designed connecting devices 16.

[0050] Fig. 6 shows a section of a perspective view of the first component 12 of the end plate 10 according to Fig. 5. The first component 12 comprises 32 peg-like projections 36.

[0051] Fig. 7 shows a cross section through one of the connecting devices 16 of the end plate 10 according to Fig. 5.

[0052] The first component 12 has 32 screw-in openings 30. The second component 10 has 32 second openings 32. The end plate 10 has 32 screws 34 (see FIG. Fig. 5). Each screw 34 is screwed through one of the second openings 32 into the respective screw-in opening 30. The screw-in openings 30, the second openings 32, and the screws 34 can be part of the respective connecting device 16.

[0053] The screw-in openings 30 are arranged on or in the pin-like elevations 36 of the first component 12. The pin-like elevations 36 are, in this case, part of the respective connecting device 16.

[0054] The second component 14 has 32 recesses 38 in each of which the pin-like projections 36 are received. The recesses 38 are part of the respective connecting device 16.

[0055] The peg-like elevations 36 each have an outer circumference 40 (or a radial outer surface). The peg-like elevations 36 are each arranged with their outer circumference 40 at a distance from the second component 14. In this case, the peg-like elevations 36 are each arranged with their outer circumference 40 at a distance from an inner circumference 42 (or a radial inner surface) of the respective recess 38. This ensures play between the first component 12 and the second component 14, and in particular between the peg-like elevations 36 and the recesses 38 in the longitudinal direction 11 and in the transverse direction 13.

[0056] The screws 34 each have a shaft portion 44 with an outer surface 46 (or an outer circumference). The shaft portions 44 of the screws 34 are arranged with their respective outer surfaces 46 at a distance from the second component 14. The shaft portions 44 of the screws 34 are arranged with their respective outer surfaces 46, in particular, relative to an inner surface 48 of the respective second opening 32. This ensures play between the first component 12 and the second component 14, in particular between the shaft portions 44 of the screws 34 and the second openings 32 in the longitudinal direction 11 and in the transverse direction 13.

[0057] Analogous to the first exemplary embodiment, the second component 14 in this case has 32 recesses 50. The recesses 50 each adjoin the second opening 32. The recesses 50 are arranged on a side (flat side) of the second component 14 facing away from the first component 12. The recesses 50 are each enlarged relative to the respective second opening 32. In other words, the diameter of the recesses 50 is each larger than the diameter of the respective second opening 32. The recesses 50 are presently part of the connecting devices 16.

[0058] The 32 connecting devices 16 of the end plate 10 according to the second, in Fig. 5 are identical in the present case. It is also conceivable that at least two of the connecting devices 16 can be designed differently. Thus, it is conceivable that the end plate 10 has connecting devices 16 according to Fig. 1 and according to Fig. 5 in combination with each other.

[0059] An outer circumference 54 (or radial outer surface) of a screw head 56 of the respective screw 34 is in this case smaller than an inner circumference 58 (or radial inner surface) of the respective countersink 50. This ensures a clearance between the first component 12 and the second component 14 and in particular between the screw heads 56 and the countersinks 50 in the longitudinal direction 11 and the transverse direction 13.

[0060] Fig. Figure 8 shows a schematic side view of a cell stack 72. The cell stack 72 comprises several bipolar plates 74 stacked on top of one another and two end plates 10 according to the above explanations. In particular, the end plates 10 can be the Fig. 1 to 4 and / or the Fig. 5 to 7. The bipolar plates 74 may be formed of graphite.

[0061] In the following, a method for producing an end plate 10 according to the above statements is described with reference to the Fig. 1 to 7. In particular, the method is a method for producing one of the Fig. 1 to 4 or in the Fig. End plate 10 shown in Figures 5 to 7.

[0062] The procedure includes the following steps: Producing and / or providing the first component 12 from plastic.

[0063] Producing and / or providing the second component 14 from metal.

[0064] Positioning the two components 12, 14 on top of each other and positively connecting the first component 12 with the second component 14.

[0065] The positive connection of the first component 12 with the second component 14 can be carried out by screwing, by riveting (hot riveting), by clipping and / or by deformation through heat input.

Claims

[1] End plate (10) for a cell stack (72), the end plate (10) comprising: - a first component (12) made of plastic, - a second component (14) made of metal, and - at least one connecting device (16), wherein the first component (12) and the second component (14) are positioned on top of one another and are connected to one another in a form-fitting manner by means of the connecting device (16), wherein the first component (12) has at least one, in particular mushroom-shaped, extension (18) with a shaft section (20) and a head section (22), wherein the second component (14) has at least one first opening (24), wherein the extension (18) with the shaft section (20) projects through the first opening (24) and engages behind the first opening (24) with the head section (22), wherein the extension (18) and the first opening (24) are components of the connecting device (16). [2] End plate (10) according to claim 1, characterized bythat the first component (12) and / or the second component (14) are each formed integrally and separately. [3] End plate (10) according to claim 1 or 2, characterized by that the shaft section (20) of the extension (18) has an outer surface (26) and is arranged with its outer surface (26) at a distance from the second component (14), in particular from an inner surface (28) of the first opening (24). [4] End plate (10) according to one of the preceding claims, characterized by that the head portion (22) of the extension (18) is formed by thermal forming. [5] End plate (10) according to one of the preceding claims, characterized byin that the first component (12) has at least one screw-in opening (30), wherein the second component (14) has at least a second opening (32), wherein the end plate (10) comprises at least one screw (34), wherein the screw (34) is screwed through the second opening (32) into the screw-in opening (30), wherein the screw-in opening (30), the second opening (32) and the screw (34) are components of the connecting device (16). [6] End plate (10) according to the preceding claim, characterized by that the screw-in opening (30) is arranged on and / or in a pin-like elevation (36) of the first component (12), in particular wherein the pin-like elevation (36) is a component of the connecting device (16). [7] End plate (10) according to the preceding claim, characterized bythat the second component (14) has at least one recess (38) into which the pin-like elevation (36) is received, in particular wherein the recess (38) is a component of the connecting device (16). [8] End plate (10) according to one of the two preceding claims, characterized by that the pin-like elevation (36) has an outer circumference (40) and is arranged with its outer circumference (40) at a distance from the second component (14), in particular from an inner circumference (42) of the recess (38). [9] End plate (10) according to one of claims 5 to 8, characterized by that the screw (34) has a shaft portion (44) with an outer surface (46), wherein the shaft portion (44) is arranged with its outer surface (46) at a distance from the second component (14), in particular from an inner surface (48) of the second opening (32). [10] End plate (10) according to one of the preceding claims, characterized bythat a countersink (50) of the second component (14) adjoins the first opening (24) and / or the second opening (32) on a side of the second component (14) facing away from the first component (12), wherein the countersink (50) is enlarged relative to the first opening (24) and / or to the second opening (32), in particular wherein the countersink (50) is a component of the connecting device (16). [11] End plate (10) according to the preceding claim, characterized by that an outer circumference (52) of the head portion (22) of the extension (18) and / or an outer circumference (54) of a screw head (56) of the screw (34) are each smaller than an inner circumference (58) of the countersink (50). [12] End plate (10) according to one of the preceding claims, characterized byin that the first component (12) has at least one continuous channel (60) which is delimited to the outside by a channel wall (62) and is open at the end, wherein the second component (14) has at least one third opening (64) into which the channel wall (62) projects, wherein the channel wall (62) is arranged at a distance from the third opening (64). [13] End plate (10) according to the preceding claim, characterized by that the channel (60) has a first mouth (66) and a second mouth (68), wherein at least one groove (70) for arranging a seal is arranged on the end face of the first mouth (66) and / or the second mouth (68), in particular in the channel wall (62). [14] Cell stack (72) comprising at least two or more bipolar plates (74) stacked on top of one another, preferably made of graphite, and at least one end plate (10) according to one of the preceding claims. [15] A method for producing an end plate (10) for a cell stack (72) according to any one of claims 1 to 13, comprising the steps: - producing and / or providing a first component (12) made of plastic; - producing and / or providing a second component (14) made of metal; - Positioning the two components (12, 14) on top of each other and positively connecting the first component (12) to the second component (14). [16] Method according to the preceding claim, characterized by that the positive connection of the first component (12) to the second component (14) is carried out by screwing, riveting, clipping and / or deformation by means of heat input.

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