Fuel cell system and motor vehicle

Abstract

The invention relates to a fuel cell system (100) comprising a fuel cell stack (110), a DC / DC converter (120), a housing (200), and one or more electrical connectors (130), wherein the one or more electrical connectors (130) electrically connect the fuel cell stack (110) to the DC / DC converter (120), and wherein the housing (200) encloses the fuel cell stack (110) and the DC / DC converter (120), and wherein the housing (200) has a flange (205) in a region laterally surrounding the DC / DC converter (120) but spaced apart from the fuel cell stack (110). The invention also relates to a motor vehicle comprising such a fuel cell system.

Description

[0001] Fuel cell system and motor vehicle

[0002] The technology disclosed here relates to a fuel cell system and a motor vehicle with such a fuel cell system.

[0003] Fuel cells are often constructed in the form of a fuel cell stack. Such a fuel cell stack can, in particular, comprise multiple electrodes and membranes between them, with two electrodes and a membrane between them forming a fuel cell. In particular, this allows gaseous fuel such as hydrogen or methane to be converted into electrical energy, which can be used, in particular, to power a motor vehicle or other device or for other functions that require electrical power.

[0004] It is a preferred object of the technology disclosed here to reduce or eliminate at least one disadvantage of a previously known solution or to propose an alternative solution. In particular, it is a preferred object of the technology disclosed here to propose a simpler and / or more stable housing. Further preferred objects can arise from the advantageous effects of the technology disclosed here. The objects are achieved by the subject matter of the independent patent claims. The dependent claims represent preferred embodiments. The technology disclosed here relates to a fuel cell system comprising (i) a fuel cell stack, (ii) a DC / DC converter, (iii) a housing, and (iv) one or more electrical connectors. The electrical connector(s) expediently electrically connect the fuel cell stack to the DC / DC converter. The housing encloses the fuel cell stack and the DC / DC converter.

[0005] Using such a fuel cell system, a housing can be provided that accommodates both the fuel cell stack and the DC / DC converter, thus enabling easy handling and joint protection.

[0006] A fuel cell stack can be understood, in particular, as a sequence of several electrodes with membranes in between. The electrodes can, in particular, be an alternating anode and a cathode. The membranes can, in particular, be polymer electrolyte membranes. The housing encloses the aforementioned components; it does not necessarily have to be formed in one piece, but can also be formed in several parts. For example, one housing part can be provided for the fuel cell stack and one housing part for the DC / DC converter. The two housing parts can be connected to one another, in particular detachably connected to one another, for example, at a location or level where the fuel cell stack and the DC / DC converter adjoin one another. As will be described further below, a one-piece design is also possible. The electrical connectors can, in particular, be designed in the form of busbars.In particular, these can be solid electrical connectors. These can be made of a conductive material such as copper, aluminum, gold, or platinum. The electrical connectors typically ensure that electrical energy is conducted from the fuel cell stack to the DC / DC converter. The DC / DC converter can convert a supplied voltage into another voltage, typically maintaining the state as a direct voltage. This can generate an output voltage suitable for operating other components such as an electric motor. The fuel cell stack, on the other hand, can be operated at a voltage that is optimized for operation, for example, with regard to efficiency.

[0007] According to one embodiment, the housing is formed in one piece at least from an area laterally surrounding the fuel cell stack to an area laterally surrounding the DC / DC converter. A one-piece design is understood in particular to mean that there is no separation point at which parts can be separated from one another without forcibly breaking material. For example, a one-piece design can be realized by producing corresponding sections in one piece, for example by casting, pressing, or injection molding. A one-piece design as just described makes it possible, in particular, to avoid a flange between the DC / DC converter and the fuel cell stack. This can increase overall stability. Furthermore, space requirements and weight are reduced.

[0008] In particular, it can be provided that the housing between the fuel cell stack and the DC / DC converter does not have a flange. A flange can be understood, in particular, as a point at which two components are releasably fastened to one another. The releasable fastening can be achieved, for example, using screws or clip connections. By omitting such a flange, greater stability and a simpler design can be achieved.

[0009] The housing can have a flange, in particular in an area laterally surrounding the DC / DC converter but spaced from the fuel cell stack, to which a first housing part and a second housing part are detachably fastened to one another. This provides a flange which can detachably fasten part of the housing so that the interior of the housing is easily accessible by detaching this part. Stability is increased by arranging this flange laterally surrounding the DC / DC converter and not between the DC / DC converter and the fuel cell stack. The flange can, for example, be arranged such that exactly or at least approximately half of the DC / DC converter is arranged in the first housing part and the other half in the second housing part. The flange can also be further away from the fuel cell than just described or closer to it.For example, the fuel cell stack and part of the DC / DC converter can be arranged in the first housing part. Another part of the DC / DC converter is then typically arranged in the second housing part. The first housing part and / or the second housing part are preferably each designed as a single piece, in particular without an additional flange. A detachable fastening can be achieved in particular by means of a screw connection, a clip connection or in another way. The distance between the flange and the fuel cell stack can, for example, be at least 10 cm or at least 20 cm. The DC / DC converter can, in particular, be block-shaped and / or cuboid-shaped. The parts of the DC / DC converter can alternatively also be referred to as sections. They do not necessarily have to be visually distinguishable from one another, but can be.A one-piece design of an element can generally be understood as meaning that it is not intended to be disassembled into two or more parts without violent destruction. In particular, a one-piece design can be considered contrary to this if there is a point at which fasteners such as screws can be loosened in a predetermined manner to obtain two parts.

[0010] According to an embodiment not covered by claim 1, the housing is formed entirely in one piece. This allows for particularly high stability. In particular, this can mean that the aforementioned flange surrounding the DC / DC converter is omitted.

[0011] The electrical connector(s) can be designed, in particular, as busbars. These are bulky connectors made of an electrically conductive material such as iron, aluminum, copper, gold, or platinum, which has a particularly low resistance value and / or is mechanically stable. This allows for high stability and a current-carrying capacity, even for high currents.

[0012] In particular, the electrical connector(s) from the fuel cell stack to the DC / DC converter can be integral. A one-piece electrical connector can be characterized, in particular, by not containing any point at which two components of the connector could be separated from one another without being forcibly broken. In particular, the electrical connector contains no components that are fastened to one another by screws or clip connections. Any fastening means for attaching the electrical connector to the fuel cell stack and / or to the DC / DC converter, such as screws or washers, do not conflict with the one-piece design.

[0013] The housing can preferably have a single shared interior space, in which the fuel cell stack and the DC / DC converter are located. In particular, the housing can be designed to be inherently stable and maintain the interior space through its own stability. In particular, the housing can be designed as a cast component. This allows for simple manufacturing and a stable design. However, other manufacturing methods are also possible in principle.

[0014] According to one embodiment, the housing has one or more supports or mounts for the fuel cell stack, the electrical connector(s), and / or the DC / DC converter. Such supports can provide suitable support for the respective component. For example, elements for shock absorption or for electrical or thermal insulation can be incorporated into such supports. Mounts can, in particular, fix the respective component in the housing, thus preventing unintentional movement within the housing.

[0015] According to an advantageous embodiment, one or more tunnels are formed in the housing to accommodate the electrical connector(s). Such tunnels can lead, in particular, from the fuel cell stack to the DC / DC converter. The tunnels can, in particular, provide electrical insulation. A tunnel can, in particular, enclose one or more electrical connectors on all sides along a section of its or their longitudinal extent. In particular, the electrical connector(s) can be electrically insulated from the housing. As a result, the housing itself can be formed from an electrically conductive material such as steel or iron, without undesired current flows or short circuits occurring. For example, such electrical insulation can be achieved using plastic insulation elements at suitable locations.

[0016] According to one embodiment, the housing has an opening on one side. This opening can, in particular, be covered by a media pressure plate. A media pressure plate is understood, in particular, to be a plate that exerts pressure on other components, in particular on the fuel cell stack. This can ensure particularly good electrical contact between the electrode plates and membranes or other components within the fuel cell stack. In particular, the media pressure plate can be connected to suitable means, such as springs, that generate such pressure.

[0017] The media pressure plate is preferably designed as a single piece. In particular, it can cover both the fuel cell stack and the DC / DC converter. This makes it particularly simple to design, as only one media pressure plate is required. This can close the aforementioned opening in the housing. Additional manufacturing steps are therefore unnecessary. The fuel cell stack and / or DC / DC converter can be covered, in particular, on one side. It can be covered completely or partially, preferably at least predominantly. According to one embodiment, a partition wall is arranged in the housing between the fuel cell stack and the DC / DC converter. Such a partition wall can be arranged, in particular, within a common interior space of the housing. In this way, a certain separation can be achieved between the installation spaces of the DC / DC converter and the fuel cell stack.For example, such a partition can provide vibration isolation. However, this should not be confused with the design with two separate housing sections, which does not have to be implemented even when using such a partition. Rather, a partition can also be arranged within a housing that is one-piece on the outside.

[0018] The fuel cell stack can, in particular, comprise a plurality of mutually parallel electrodes, which can be aligned transversely to a separation plane and / or a partition wall between the fuel cell stack and the DC / DC converter. An arrangement transversely to the separation plane or partition wall can achieve an advantageous geometry, allowing busbars and media supply and discharge lines, in particular, to be routed advantageously. This can lead to a particularly compact design.

[0019] The technology disclosed here further relates to a motor vehicle having a fuel cell system as described herein. With regard to the fuel cell system, all embodiments and variants described herein can be used. The advantages already described can be achieved.

[0020] A fuel cell or a fuel cell stack can in particular be configured as an energy converter, which can in particular convert the chemical energy of a fuel into other forms of energy, for example into electrical energy and / or kinetic energy. For example, the technology disclosed here can be used in mobile applications such as motor vehicles (e.g., passenger cars, motorcycles, commercial vehicles), in particular to provide energy for at least one drive motor for propulsion of the motor vehicle. In its simplest form, a fuel cell is an electrochemical energy converter that converts fuel (e.g., hydrogen) and oxidants (e.g., air, oxygen, and peroxides) into reaction products, thereby producing electricity and heat.

[0021] The electrodes of the fuel cell can, in particular, be anodes and cathodes. These can, in particular, be separated by an ion-selective or ion-permeable separator. The anode is supplied with fuel. Preferred fuels are hydrogen, low-molecular-weight alcohol, biofuels, or liquefied natural gas. The cathode is typically supplied with an oxidizing agent. Preferred oxidizing agents are, for example, air, oxygen, and peroxides. The ion-selective separator can, for example, be designed as a proton exchange membrane (PEM). A cation-selective polymer electrolyte membrane is preferably used. The DC / DC converter can, in particular, be designed as a voltage converter. This can, in particular, be configured to convert a primary voltage into a secondary voltage, in particular with regard to voltage level. The voltage converter can also be referred to as a power converter.The voltage converter can, in particular, form an electrical coupling element between at least one fuel cell, which generates the primary voltage from the primary voltage network, and at least one energy storage device and / or at least one electric drive motor, to which the secondary voltage from the secondary voltage network is applied. Further components can be provided on both the primary and secondary sides of the voltage converter. The DC / DC converter is preferably designed as a direct current converter. For this purpose, the voltage converter can be connected to an electrical intermediate circuit of the motor vehicle. The voltage converter can function as a boost converter and / or a buck converter. The voltage converter itself can have a control unit. Alternatively, the control functionality can also be assumed by the control unit of the fuel cell system and / or by a higher-level control unit.

[0022] In particular, the previously described one-piece media pressure plate can be combined with a one-piece housing, or at least a one-piece housing at a connection point between the DC / DC converter and the fuel cell stack. This results in a particularly stable and simple design.

[0023] In other words, the installation space in the front of a vehicle is particularly limited and will become even smaller, especially in future fuel cell vehicle architectures. Therefore, it makes sense to identify and exploit potential for reducing installation space. A flange between two components with a similar footprint (fuel cell stack, DC / DC converter) is therefore suboptimal in terms of installation space, as the inventors of the present application have discovered. This is particularly the case due to its circumferential cantilevered nature. In addition, it has been shown that a flange between two components can fundamentally be a weak point that can lead to acoustic abnormalities, which are counteracted with design measures that increase complexity and weight.Due to their high efficiency and low emissions, fuel cells, along with rechargeable batteries, are among the most important power sources for future motor vehicles. Fuel cells are used in particular for fuel cell electric drives. A fuel cell electric drive comprises a multitude of components, including a fuel cell stack comprising a plurality of fuel cells for converting chemical reaction energy into electrical energy and a DC / DC converter for regulating the power flow from the fuel cell stack to a high-voltage battery and / or other components. The fuel cell stack and the DC / DC converter are typically arranged in separate housings, for example, next to or above one another. Such housings are typically bolted together.These housings are typically only connected locally, via screw connections, so optimal rigidity, strength, and acoustics are not guaranteed. Furthermore, it is typically necessary to ensure the quality of the screw connections. A flange plane between the components also requires its own installation space, which is not available for other components or functions. Several mechanical interfaces between the individual components must be coordinated, implemented, and sealed.

[0024] In particular, it is therefore proposed to integrate the fuel cell stack and the DC / DC converter into a common housing. Furthermore, bearing blocks and / or bearing supports for positioning the fuel cell stack or the fuel cell system can be integrated into the common housing. This offers the particular advantage that only one housing is produced for the two components of the fuel cell system, which is more compact and lighter than two separate, interconnected housings. Since local connections by screwing two components together are eliminated, the integrated component achieves greater rigidity and strength, as well as improved acoustics. Furthermore, quality inspection of the flange connection is no longer necessary.

[0025] It should be understood, in particular, that the sub-features disclosed herein, namely the fully or at least partially integral design of a housing (elimination of a flange at the connection point between the DC / DC converter and the fuel cell stack), the integral busbars, and the integral media pressure plate, can be considered functionally independent of one another. These can therefore also be claimed independently of one another. Nevertheless, together they can produce a synergistic effect.

[0026] According to an alternative embodiment, it can also be provided that the media pressure plate only closes an opening which is arranged only adjacent to the fuel cell stack, but not adjacent to the DC / DC converter.

[0027] In particular, the housing uses only a single structural component, which assumes load-bearing properties and integrates the stack and power electronics. The integral housing integrates the fuel cell stack, the power electronics, and busbars, whereby support brackets and / or mounts can already be cast onto the housing. The integral housing, as a cast component, can assume all structural functions. A housing assembly can serve as a functional carrier to which additional components are mounted. To minimize installation space requirements, reduce assembly effort, and optimize the structure, a large media pressure plate can be used that spans the DC / DC converter. This integrates the media interface of the fuel cell stack and the mounting cover for the power electronics.

[0028] To minimize installation space requirements and simplify assembly, busbars, which conduct the current generated in the fuel cell stack to the power electronics, can be pushed from the power electronics side through a channel in the housing to the fuel cell stack. The busbars can be locally overmolded with an insulating material in the transition area between the stack and the power electronics, to which a seal is attached. The busbars can be screwed in from the power electronics side in the screw-in direction.

[0029] By designing the housing as a structural component, for example as an injection-molded part, it is possible to avoid the need for additional support.

[0030] The technology disclosed here will now be described with reference to the figures, which show:

[0031] Fig. 1 : a fuel cell system according to an embodiment,

[0032] Fig. 2: a fuel cell system according to another

[0033] Example,

[0034] Fig. 3: a fuel cell system according to another

[0035] embodiment, and

[0036] Fig. 4: A partial interior view of a fuel cell system. Fig. 1 shows an embodiment that has a flange surrounding a DC / DC converter and therefore falls under claim 1. The other figures show alternative embodiments without such a flange.

[0037] Fig. 1 shows a fuel cell system 100 according to an embodiment in a purely schematic view, wherein some components are not shown and some components are not connected to each other.

[0038] The fuel cell system 100 includes a fuel cell stack 110 and a DC / DC converter 120. These components are shown only schematically here, as their internal functionality will not be discussed further here. The fuel cell stack 110 is fundamentally designed to generate electrical energy from gaseous fuel or from another fluid fuel. The DC / DC converter is designed to transform a voltage supplied by the fuel cell stack into another voltage.

[0039] The fuel cell system 100 has a housing 200. The housing 200 is divided into a first housing part 201 and a second housing part 202. These can be connected to each other at a flange 205, although they are not connected to each other in the illustration of Fig. 1. The connection can be made in the usual way via screw connections.

[0040] A separation plane 230 is provided between the fuel cell stack 110 and the DC / DC converter 120. This plane is depicted here only as a purely virtual plane, with the fuel cell stack 110 and the DC / DC converter 120 adjacent to one another or at least minimally spaced from one another at this location. Immediately outside such a location, where the fuel cell stack 110 and the DC / DC converter 120 are adjacent to one another or at least minimally spaced from one another, and in particular at the separation plane 230, the housing 200 or the first housing part 201 is formed in one piece. No flange is provided at this location, which could be used to separate two housing parts from one another without violent destruction.

[0041] The housing 200 encloses an interior space 207, which is divided into a first receiving space 210 for the fuel cell stack 110 and a second receiving space 220 for the DC / DC converter 120. The two receiving spaces 210, 220 adjoin one another at the separation plane 230, although this separation may also be purely virtual.

[0042] An opening 208 is formed on one side of the first receiving space 210. In the fully assembled state, this opening is closed by a media pressure plate, which is not shown in Fig. 1, however. This allows pressure to be exerted on the fuel cell stack 110, for example, to better press the electrodes and membranes together. In the embodiment shown in Fig. 1, this opening 208 does not extend to an area surrounding the DC / DC converter 120.

[0043] Fastening elements 240 are provided for fastening the housing 200. This allows the housing 200 to be fastened to a body of a motor vehicle, or it can also be fastened to other components. A stable design of the housing 200 means that no additional support elements or other stabilizing elements are required for the housing 200. Fig. 2 shows a fuel cell system 100 according to a second exemplary embodiment. In contrast to the first exemplary embodiment, the housing 200 is initially open on the entire side facing to the front left and is closed by a media pressure plate 251 and a cover 252. In contrast to the design of Fig. 1, an opening is thus also formed immediately surrounding the DC / DC converter 120, which opening is closed by the cover 252. The cover 252 is thus a cover of the DC / DC converter.This allows easier access to the second receiving space 220, in which the DC / DC converter 120 is located. In contrast, the flange 205 and thus the two-part housing 200 are omitted in the embodiment of Fig. 2. The media pressure plate 251 typically serves to exert pressure on the fuel cell stack 110. The cover 252, in contrast, merely covers the opening.

[0044] Fig. 3 shows a purely schematic view of a fuel cell system 100 according to a third exemplary embodiment. In contrast to the second exemplary embodiment, there is no cover, but rather only a single, common, and integrally constructed media pressure plate 250. This media pressure plate 250 closes the entire opening 208, i.e., both directly adjacent to the fuel cell stack 110 and directly adjacent to the DC / DC converter 120.

[0045] In the present case, a partition 260 is formed at the parting plane 230. This separates the first receiving area 210 from the second receiving space 220, but does not result in housing parts being able to be separated from one another without force at this point. The housing 200 is nevertheless formed in one piece at this point. In Figs. 2 and 3, a total of six media interfaces 255 are provided in the media pressure plate 251 and in the media pressure plate 250, respectively. These allow an advantageous supply and removal of media such as gaseous fuel and air to and from the fuel cell stack 110, provided its electrodes are aligned transversely to the parting plane 230 or partition 260, since media connections are typically routed transversely to the electrodes. A design with electrodes parallel to the parting plane 230 or partition 260 would displace the media interfaces 255 to one end side and thus increase the installation space requirement.

[0046] Fig. 4 shows a sectional view of the interior of a housing 200. The fuel cell stack 110 and the DC / DC converter 120 are schematically shown side by side within the housing 200. The partition wall 260 is located between them, as already mentioned with reference to Fig. 3.

[0047] An electrical connector 130 is provided for the electrical connection between the fuel cell stack 110 and the DC / DC converter 120. In this case, it is designed as a busbar. It is formed as a single piece, meaning that there is no force-removable connection between a terminal of the DC / DC converter 120 and a terminal of the fuel cell stack 110. This allows for a particularly simple design.

[0048] The electrical connector 130 runs in a tunnel 270 formed within the housing 200. The tunnel 270 is designed such that the electrical connector 130 can be inserted therein and is electrically insulated from the rest of the housing 200, particularly if this is required due to a housing material. The tunnel 270 runs, in particular, below the partition wall 260. In particular, several such electrical connectors 130 can be present, for example, to electrically connect a positive pole and a negative pole of the fuel cell stack 110 to corresponding terminals of the DC / DC converter 120.

[0049] For the sake of readability, the term "at least one" has been partially omitted. If a feature of the technology disclosed here is described in the singular or indefinitely (e.g., the fuel cell stack, the DC / DC converter, etc.), the plural form is also intended to be disclosed (e.g., the at least one fuel cell stack, the at least one DC / DC converter, etc.).

[0050] The foregoing description of the present invention is for illustrative purposes only and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention and its equivalents.

[0051] List of reference symbols

[0052] 100 fuel cell system

[0053] 110 fuel cell stacks

[0054] 120 DC / DC converters

[0055] 130 electrical connectors

[0056] 200 housings

[0057] 201 first housing part

[0058] 202 second housing part

[0059] 205 flange

[0060] 207 Interior

[0061] 208 Opening

[0062] 210 first recording room

[0063] 220 second recording room

[0064] 230 parting line

[0065] 240 fasteners

[0066] 250 media printing plate

[0067] 251 Media pressure plate

[0068] 252 lids

[0069] 255 media interfaces

[0070] 260 partition wall

[0071] 270 tunnels

Claims

Claims 1. Fuel cell system (100), comprising - a fuel cell stack (110), - a DC / DC converter (120), - a housing (200), and - one or more electrical connectors (130), wherein the electrical connector(s) (130) electrically connect the fuel cell stack (110) to the DC / DC converter (120), wherein the housing (200) encloses the fuel cell stack (110) and the DC / DC converter (120), and wherein the housing (200) has, in a region laterally surrounding the DC / DC converter (120) but spaced apart from the fuel cell stack (110), a flange (205) to which a first housing part (201) and a second housing part (202) are detachably fastened to one another.

2. Fuel cell system (100) according to claim 1, wherein the housing (200) is formed in one piece at least from a region laterally surrounding the fuel cell stack (110) to a region laterally surrounding the DC / DC converter (120).

3. Fuel cell system (100) according to claim 1 or 2, wherein the housing (200) has no flange between the fuel cell stack (110) and the DC / DC converter (120).

4. Fuel cell system (100) according to one of the preceding claims, wherein in the first housing part (201) the fuel cell stack (110) and a part of the DC / DC converter (120) are arranged and another part of the DC / DC converter (120) is arranged in the second housing part (202).

5. Fuel cell system (100) according to one of the preceding claims, wherein the first housing part (201) and / or the second housing part (202) is / are each designed in one piece.

6. Fuel cell system (100) according to one of the preceding claims, wherein the electrical connector(s) (130) are designed as busbars.

7. Fuel cell system (100) according to one of the preceding claims, wherein the electrical connector(s) (130) from the fuel cell stack (110) to the DC / DC converter (120) are integral.

8. Fuel cell system (100) according to one of the preceding claims, wherein the housing (200) has exactly one common interior space (207) in which the fuel cell stack (110) and the DC / DC converter (120) are located.

9. Fuel cell system (100) according to one of the preceding claims, wherein the housing (200) is formed as a cast component.

10. Fuel cell system (100) according to one of the preceding claims, wherein the housing (200) has one or more supports or holders for the fuel cell stack (110), the electrical connector(s) (130) and / or the DC / DC converter (120).

11. Fuel cell system (100) according to one of the preceding claims, wherein one or more tunnels (270) are formed in the housing (200) for receiving the electrical connector(s) (130).

12. Fuel cell system (100) according to one of the preceding claims, wherein the electrical connector(s) (130) are electrically insulated from the housing (200).

13. Fuel cell system (100) according to one of the preceding claims, wherein the housing (200) has an opening (208) on one side, which is covered by a media pressure plate (250).

14. The fuel cell system (100) of claim 13, wherein the media pressure plate (250) integrally covers both the fuel cell stack (110) and the DC / DC converter (120).

15. Fuel cell system (100) according to one of the preceding claims, wherein a partition wall (260) is formed in the housing (200) between the fuel cell stack (110) and the DC / DC converter (120).

16. Fuel cell system (100) according to one of the preceding claims, wherein the fuel cell stack (110) has a plurality of mutually parallel electrodes which are aligned transversely to a separation plane (230) and / or to a separation wall (260) between the fuel cell stack (110) and the DC / DC converter (120).

17. Motor vehicle comprising a fuel cell system (100) according to one of the preceding claims.

Images