Fuel cell stack with at least two cell rows, fuel cell device and motor vehicle

Abstract

The invention relates to a fuel cell stack (1) which is received in a housing (6) with a first cover (7) and a second cover (8) and which has a tensioning system (11) and a plurality of fuel cells (2) which are arranged in at least two cell rows (3) between a first end plate (4) and a second end plate (5), of which first and second end plates at least the first end plate (4) has a media connection (9) and a distribution structure (10) for the distribution of media, wherein the first end plate (4) forms the first cover (7) of the housing (6). The invention furthermore relates to a fuel cell device and to a motor vehicle.

Description

Technical Field

[0001] The present invention relates to a fuel cell stack housed within a casing having a first cover and a second cover, the fuel cell stack having a tensioning system and a plurality of fuel cells, the fuel cells being arranged in at least two battery packs between a first end plate and a second end plate, wherein at least the first end plate has a dielectric connection portion and a distribution structure for dielectric distribution, wherein the first end plate forms a first cover of the casing. The present invention also relates to a fuel cell device and a motor vehicle. Background Technology

[0002] Fuel cells are used to provide electrical energy through an electrochemical reaction. Each fuel cell includes an anode, a cathode, and a proton-conducting membrane separating the anode and cathode, which is coated with a catalyst to facilitate the electrochemical reaction. Furthermore, in a fuel cell stack, bipolar plates are provided on both sides of the membrane for each fuel cell to supply the medium, i.e., reactants, and, if possible, a coolant, and a gas diffusion layer is typically used to ensure that the reactants drawn from the bipolar plates are distributed as uniformly as possible across the entire surface of the catalyst-coated membrane. To increase the available power, multiple fuel cells can be combined in series to form a fuel cell stack.

[0003] This combination of multiple fuel cells in a fuel cell stack is typically achieved by using traction elements to compress them with forces ranging from several tons, in order to achieve sufficient contact pressure at the catalyst-coated membrane to reduce ohmic losses and to avoid unsealing of the seals used by means of high compression.

[0004] However, it is important to note that the following forces occur during the operation of a fuel cell stack, which can lead to an increase or decrease in compressive stress. An increase in compressive stress is caused by the thermal expansion of the components used, by the pressure applied to supplying and distributing the reactants, and by the expansion of the membranes used during hydration.

[0005] The reduction in compressive stress can occur through negative thermal expansion under conditions of temperature drop or at low temperatures, or through the settling behavior of the gas diffusion layer and seals, which increases with the duration of use and therefore the lifespan of the fuel cell stack.

[0006] Furthermore, it's important to note that with increased power demand, it's possible to distribute fuel cells across at least two parallel battery banks, for example, if available installation space necessitates this, where the compression requirements remain constant. It's also crucial to ensure the medium flow is distributed as evenly as possible across the battery banks.

[0007] DE112007002793B4 describes a fuel cell stack having fuel cells distributed on two battery banks arranged between two end plates. These end plates are interconnected by a pair of tension plates. Injector nozzles for reactant gases are arranged on one of the end plates, wherein the reactant gas conduit includes an elastic region received within a housing. DE102019110317A1 discloses a modular range extender system for an electric motor vehicle having multiple fuel cell stacks, wherein the fuel cells can be arranged in two side-by-side battery banks. At least one end plate then has an interface for a medium guide. The medium is guided through the two battery banks in a U-shaped medium guide. The other end plate has a reversing conduit for this purpose. DE102015224178A1 shows a redox fuel cell system in which a fuel cell stack with only one battery bank is arranged next to a regenerator stack. Summary of the Invention

[0008] The objective of this invention is to construct a fuel cell stack in a way that simplifies its manufacture. Further objectives are to provide an improved fuel cell device and an improved motor vehicle.

[0009] The task is accomplished by means of a fuel cell stack according to the invention, a fuel cell device according to the invention, and a motor vehicle according to the invention.

[0010] The fuel cell stack mentioned at the beginning is characterized in that the first end plate of the fuel cell stack with the median connection is also an integral part of the housing. Since this first end plate also supports the median connection for the two battery banks, the number of required components is reduced, resulting in lower installation space requirements and a reduced number of sealing points. The common first end plate with the median connection creates a common assembly that can be treated as a single component during manufacturing, thereby optimizing the manufacturing process. This is associated with time and cost savings, precisely because the first end plate also forms the first cover of the housing. The placement of the first cover as the first end plate only needs to be done once for both battery banks, and the compression of the tensioning system for the two battery banks is also performed in a single method step, further reducing cycle time during manufacturing.

[0011] Preferably, the second end plate forms the second cover of the housing, as this saves on components, further integrates the fuel cell stack into the housing, and simplifies the handling during manufacturing.

[0012] There is also the possibility that at least two sidewalls arranged on opposite sides of the housing form a tensioning system between the first cover and the second cover, thus enabling the housing to be used more versatilely again and increasing the integration of the fuel cell stack into the housing.

[0013] If the second cover is formed as a spring cover having at least one spring supported on the second end plate, improved tolerance compensation is provided.

[0014] Here, the second end plate can be formed in multiple pieces, and each sub-plate is associated with one of these springs, so that the battery packs can be different in length, and tolerance compensation is performed for each individual battery pack to the degree required individually.

[0015] It is not mandatory for the housing as a whole to form a tensioning system, but it is possible that the tensioning element is part of the tensioning system arranged between the first cover and the second cover, that is, only the covers of the housing form part of the tensioning system, wherein the tensioning element is formed by tensioning bands and / or tensioning rods and / or zugankers.

[0016] The aforementioned advantages and functions apply, in a sense, to fuel cell devices with such fuel cell stacks and motor vehicles with such fuel cell devices, wherein, in particular, the installation space provided in motor vehicles can be better utilized through the formation of battery packs while optimizing the costs associated with manufacturing complex fuel cell stacks.

[0017] The features and combinations of features mentioned above in the description, as well as those mentioned below in the description of the accompanying drawings and / or shown separately in the drawings, may be used not only in the corresponding given combinations, but also in other combinations or individually, without departing from the scope of the invention. Therefore, the following embodiments, which are not explicitly shown or explained in the drawings but are known from and can be produced by individual combinations of features in the explained embodiments, should also be considered as included and disclosed by the invention. Attached Figure Description

[0018] Other advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the accompanying drawings. Herein:

[0019] Figure 1 A schematic diagram of a fuel cell stack with two battery banks, tensioned between the first and second covers of the housing via the sidewalls of the housing, is shown.

[0020] Figure 2 The corresponding second cover with a spring cover is shown. Figure 1 The illustration,

[0021] Figure 3The diagram shows a corresponding end plate with a second end plate formed by two sub-plates. Figure 2 The illustration, and

[0022] Figure 4 This illustrates a tensioning system with sidewalls formed independently of the housing, corresponding to... Figure 2 The illustration. Detailed Implementation

[0023] exist Figure 1 The diagram schematically illustrates a fuel cell stack 1 consisting of multiple fuel cells 2 connected in series. Each fuel cell 2 includes an anode and a cathode, and a proton-conducting membrane separating the anode and cathode. This membrane is formed of an ionomer, preferably a polymer of sulfonated tetrafluoroethylene (PTFE) or perfluorosulfonic acid (PFSA). Alternatively, the membrane can be formed as a sulfonated hydrocarbon membrane.

[0024] Fuel (e.g., hydrogen) is supplied to the anode via the anode space within the fuel cell stack 1. In a polymer electrolyte membrane fuel cell (PEM fuel cell), fuel or fuel molecules split into protons and electrons at the anode. The membrane allows protons (such as H+) to be released into the anode. + ) passes, but for electrons (e - It is impermeable to the anode. Here, the following reaction occurs at the anode: 2H₂ → 4H₂ + +4e - (Oxidation / Electron Release). During the process of protons passing through the membrane to the cathode, electrons are conducted to the cathode or accumulator via external circuitry. Cathode gas (e.g., oxygen or oxygen-containing air) can be supplied to the cathode via the cathode space within fuel cell stack 1, thereby causing the following reaction to occur on the cathode side: O₂ + 4H₂O + +4e - →2H2O (reduction / electron absorption).

[0025] exist Figure 1 In the fuel cell stack 1 schematically shown, multiple fuel cells 2 are arranged in two battery rows 3, which are positioned between a first end plate 4 and a second end plate 5. These two battery rows 3 are received within a housing 6 having a first cover 7 and a second cover 8. In the illustrated embodiment, at least one, namely the first end plate 4, has a medium connection portion 9 and a dispensing structure 10 for dispensing the medium, indicated by an arrow. Note that the first end plate 4 forms the first cover 7 of the housing 6. According to... Figure 1 In this embodiment, the second end plate 5 forms the second cover 8 of the housing 6.

[0026] The fuel cell stack 1 has a tensioning system 11 that acts between a first cover 7 and a second cover 8. Figure 1 In this case, the tensioning system is formed by at least two sidewalls 12 arranged on opposite sides of the housing 6.

[0027] Figure 2 It is shown that the second cover 8 can be formed as a spring cover 13 with at least one spring 14 supported on the second end plate 5. Here, the sidewalls 12 of the housing 6 also cause mechanical tension in the fuel cell stack 1 along with its two battery rows 3. The sidewalls 12 can exist individually as separate components; more simply and therefore preferably, the sidewalls 12 are combined into a single component in the circumferential direction, especially as a hollow, approximately square component.

[0028] Figure 3 This indicates that the second end plate 5 is formed in multiple parts, and each sub-plate is associated with one of the springs 14. Thus, the individual battery packs 3 can differ in length, with tolerances compensated by the springs 14 of the tensioning system 11.

[0029] exist Figure 4 As shown, instead of or attached to the sidewall 12 of the housing 6, the tensioning element can also form a tensioning system 11 arranged between the first cover 7 and the second cover 8, wherein the tensioning element is formed by a tensioning band and / or a tensioning rod and / or a tie rod.

[0030] The use of a fuel cell device with such a fuel cell stack 1 enables improved full utilization of installation space with simplified manufacturing, which provides particular advantages when used in motor vehicles.

[0031] List of reference numerals in the attached diagram:

[0032] 1. Fuel Cell Stack

[0033] 2. Fuel Cell

[0034] 3 Battery Pack

[0035] 4 First end plate

[0036] 5 Second end plate

[0037] 6. Shell

[0038] 7 First cover piece

[0039] 8 Second cover

[0040] 9. Medium connection part

[0041] 10. Allocation Structure

[0042] 11 Tensioning System

[0043] 12 sidewalls

[0044] 13 Spring Cover

[0045] 14. Spring.

Claims

1. A fuel cell stack (1), the fuel cell stack being received in a housing (6) having a first cover (7) and a second cover (8), and the fuel cell stack having a tensioning system (11) and a plurality of fuel cells (2), the fuel cells being arranged in at least two battery packs (3) between a first end plate (4) and a second end plate (5), the first end plate (4) of the first end plate and the second end plate having a medium connection portion (9) and a distribution structure (10) for medium distribution, characterized in that, The first end plate (4) forms the first cover (7) of the housing (6), and the second cover (8) is formed as a spring cover (13) having at least one spring (14) supported on the second end plate (5). The second end plate (5) is formed in multiple pieces and each sub-plate is associated with one of the springs (14).

2. The fuel cell stack (1) according to claim 1, characterized in that, At least two sidewalls (12) arranged on opposite sides of the housing (6) are utilized in a tensioning system (11) arranged between the first cover (7) and the second cover (8).

3. The fuel cell stack (1) according to claim 1 or 2, characterized in that, The tensioning element is part of the tensioning system (11) arranged between the first cover (7) and the second cover (8).

4. The fuel cell stack (1) according to claim 3, characterized in that, The tensioning element is formed by a tensioning belt and / or a tensioning rod and / or a tie rod.

5. A fuel cell device, the fuel cell device having a fuel cell stack (1) according to any one of claims 1 to 4.

6. A motor vehicle equipped with a fuel cell device having a fuel cell stack (1) according to any one of claims 1 to 4.

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