Insulation plate for a fuel-cell stack

Abstract

The invention relates to an insulation plate (100) for a fuel-cell stack (10) of a fuel-cell assembly, preferably for a fuel-cell vehicle, having a plate base (101), wherein an anode-inlet port (113) and, associated therewith, an anode-outlet port (114) as well as a cathode-inlet port (115) and, associated therewith, a cathode-outlet port (116) are provided in the plate base (101), and a fluid bypass (130; 133, 135) is provided in the insulation plate (100) between at least one inlet port (113, 115) and at least one associated outlet port (114, 116), the inlet port (113, 115) being brought into fluid communication with the associated outlet port (114, 116) through this fluid bypass.

Description

[0001] Description

[0002] title

[0003] Insulation plate for a fuel cell stack

[0004] The invention relates to an insulation plate and a fuel cell stack for a fuel cell unit. Furthermore, the invention relates to a fuel cell unit, a fuel cell system, or a fuel cell vehicle.

[0005] State of the art

[0006] In a low-temperature polymer electrolyte fuel cell of a fuel cell unit (stationary or mobile), e.g., a fuel cell system, e.g., a fuel cell vehicle, an electrochemical conversion of two reactants of two operating media into electrical energy and heat takes place. The fuel cell comprises at least one membrane electrode device, e.g., a membrane electrode assembly (MEA). Typically, the fuel cell is configured with a plurality of membrane electrode devices arranged in a stack with bipolar plates arranged between them (fuel cell stack or stack with a plurality of individual fuel cells).

[0007] Task

[0008] Water in an individual cell of a fuel cell stack can impede the supply of, in particular, the anode operating medium. This can lead to fuel starvation (lack of (anode) operating medium) and / or another functional problem, which in turn leads to a strongly negative potential in an affected individual cell and, consequently, to the triggering of irreversible damage mechanisms and / or damage in the fuel cell stack. - It is an object of the invention to prevent, if possible, the ingress of water into an individual cell of a fuel cell stack.

[0009] Disclosure of the invention

[0010] The object of the invention is achieved by means of an insulation plate for a fuel cell stack of a fuel cell unit, preferably for a fuel cell vehicle; by means of a fuel cell stack for a fuel cell unit, preferably for a fuel cell vehicle; as well as a fuel cell unit, a fuel cell system, and a fuel cell vehicle. Advantageous developments, additional features, and / or advantages of the invention emerge from the dependent claims and the following description.

[0011] The insulation plate according to the invention comprises a plate base, wherein in the plate base there are preferably arranged an anode inlet port and preferably an anode outlet port associated therewith, as well as preferably a cathode inlet port and preferably a cathode outlet port associated therewith, wherein in the insulation plate a fluid bypass is arranged between at least one inlet port and at least one associated outlet port, through which fluid bypass the inlet port is brought into fluid communication with the associated outlet port, i.e. can be brought into fluid communication and / or is brought into the fuel cell stack.

[0012] When the insulation plate is installed in the fuel cell stack, its anode inlet port is in fluid communication with its anode outlet port across the fuel cell stack, and its cathode inlet port is in fluid communication with its cathode outlet port across the fuel cell stack. The anode inlet port and the cathode inlet port are regions of the fuel cell assembly in an end section of an anode supply path and a cathode supply path, respectively, upstream of the actual cell stack. The anode outlet port and the cathode outlet port are regions of the fuel cell assembly in an initial section of an anode exhaust path and a cathode exhaust path, respectively, downstream of the actual cell stack. According to the invention, a fluid bypass (product water, condensed droplets, steam, small portion of possibly recirculating operating medium) is created in the insulation plate to prevent cell flooding with a fluid.This fluid bypass creates a fluid or gas bypass (see the state of the art below) already upstream of the actual cell stack, eliminating the need for complex dummy cells for a fluid bypass. This prevents cell flooding, particularly in the first upstream individual cell of the fuel cell stack. Due to early removal, there is less disruptive product water on the anode and / or cathode sides.

[0013] Furthermore, a decisive advantage of this design solution lies in comparison with solutions at the operational level. The operating parameters of a fuel cell stack often cannot be adjusted in such a way that no liquid product water enters the anode, especially under transient conditions. This design solution separates this requirement from those of operational management. The operating parameters of the fuel cell stack can be optimized for robustness and efficiency.

[0014] The fluid bypass can be arranged in the plate base and, apart from it, in the insulation plate, or exclusively in the plate base. Furthermore, the fluid bypass can have a throttling cross-section at least at one point, in sections, or essentially over its entire extent. A hydraulically effective cross-section of the fluid bypass can approximately correspond to that of an anode-side or cathode-side flow field of a bipolar plate, preferably including a distributor field.

[0015] The cross-section of the fluid bypass can approximately correspond to a hydraulically or fluid-mechanically effective cross-section or a pressure drop of an anode flow field or a cathode flow field including a distributor field on the anode side or the cathode side of a bipolar plate, in particular the first upstream bipolar plate. In the present case, this can be an approximately square cross-section with an edge length of approximately 1.5 mm or an analogue thereof, and depending on the design, up to ±25%. It should be noted that essentially the entire fluid bypass from the inlet port to the outlet port has this cross-section.

[0016] The fluid bypass can be configured in sections or substantially entirely as a fluid line, wherein, in particular, the fluid line has at least or precisely one fluid path for an anode operating medium or a cathode operating medium of the fuel cell stack. The fluid line can be configured as a narrow, throttling fluid line over a major or substantially entire extent.

[0017] The fluid line (fluid bypass) can be designed, at least in sections, as a groove that is open on one side in the circumferential direction and / or as a through-hole that is completely closed in the circumferential direction. The circumferential direction is naturally that of the fluid line. Furthermore, the fluid line can have, at least in sections or substantially over its entire extent, a polygonal, V-shaped, rectangular, U-shaped, or elliptical cross-section. A rectangular cross-section (preferably a groove) is particularly suitable, and a circular cross-section is particularly suitable as an elliptical cross-section (preferably a bore).

[0018] The plate base can have a water trap at the inlet port and / or at the outlet port. The water trap can be arranged in the plate base so as to run at least partially around the port and / or can be provided on / in the port so as to run at least partially around the port. The water trap can be arranged so as to extend directly into the plate base at an edge of the port and / or can be provided so as to protrude into the port of the plate base. The water trap can widen the port, in particular in the radial direction of the port (recess). In this case, the water trap can open on the surface of the plate base which faces the fuel cell stack. Furthermore, the water trap can reduce the inlet port, in particular in the radial direction of the port (protrusion). In this case, an opening of the fluid bypass is then located downstream below.

[0019] The water trap can be configured as a recess inside a wall of the port and, if appropriate, also a port connection. The recess opens at / in the port, with a main extension of the recess extending at least in a circumferential direction and / or in a longitudinal direction of a port connection. Such a water trap particularly captures excess product water (including condensed droplets and vapor), which is conveyed in a timely manner from the inlet port through the fluid bypass to the outlet port. Such a recess for a water trap can be easily realized by injection molding the insulation plate.

[0020] Furthermore, the water trap can have a projection on the inside of a wall of the port, wherein the projection extends at least partially or completely around and / or within the port. The projection can be an integral part of a wall of the port or formed by a part on / in the inlet connection. Such a projection for a water trap can be realized simply by injection molding the insulation plate or by overmolding an insert in the insulation plate. The water trap in question can be in substantially unthrottled fluid communication with the port.

[0021] The fluid bypass can be configured in sections or exclusively as a groove from the inlet port to the associated outlet port. In this case, the fluid bypass can be configured in sections essentially parallel to an edge of the end plate recess in the plate base. Here, the fluid bypass can establish a primarily or essentially direct connection between the inlet port and the associated outlet port, naturally preferably bypassing the end plate recess. Alternatively, the fluid bypass can also be configured in the plate base in such a way that it bypasses at least one other port.

[0022] Furthermore, the fluid bypass can be configured in sections as a through-hole leading away from the inlet port and / or opening into the outlet port. Of course, the fluid bypass can also lead away from an inlet / outlet connection relating to the port or open into an outlet / inlet connection relating to the port. Furthermore, the fluid bypass can be configured in sections as a recess delimited by a second component of the fuel cell stack. The insulation plate can have at least two or exactly two fluid bypasses. The fluid bypasses can be configured in the insulation plate so as to be fluid-mechanically separated from one another over their entire extent. Furthermore, an intersection of the fluid bypasses can be configured such that, in the region of the intersection, one fluid bypass is configured above the other fluid bypass in the plate base.In this case, in the area of ​​the intersection, one fluid bypass can be designed as a groove and the other as a through-hole. Furthermore, two fluid bypasses can be arranged parallel to each other in the plate base, laterally adjacent to the end plate recess. The respective fluid can flow through the parallel sections of the fluid bypasses in parallel or antiparallel.

[0023] The smallest cross section of the fluid bypass can be approx.: 1.25mm 2 , 1 ,5mm 2 , 1 ,75mm 2 , 2.0mm 2 , 2.25mm 2 , 2.5mm 2 , 2.75mm 2 , 3mm 2 or 3.25mm 2±10% each. The end plate recess for an end plate of the fuel cell stack can preferably be arranged in the plate base between ports arranged therein on two sides. An end plate of the fuel cell stack can be centered in the end plate recess, wherein the end plate recess is preferably not designed as a through-hole, or no large-area through-hole of the insulation plate is arranged within the end plate recess.

[0024] Inlet ports for inflowing media of the fuel cell stack and outlet ports for outflowing media of the fuel cell stack can be formed on the plate base. The ports for the media of the fuel cell stack are preferably located on a side of the plate base opposite the end plate recess. All ports are preferably formed on a single, large-area side of the plate base, particularly away from the end plate recess. A respective inlet port and a respective outlet port each form an opening of a respective inlet port and a respective outlet port on the inside of the insulation plate for the fuel cell stack mounted thereon.

[0025] The insulation panel can be constructed as a single piece or integrally. A single piece (adhesive) construction refers to an insulation panel construction in which its individual components are firmly bonded to one another (by adhesive bonding, two-component injection molding, etc.), and the insulation panel is preferably not separable into individual parts without damaging one of its individual components. The insulation panel can also be held together by means of a force and / or form fit (not in the case of an integral construction).

[0026] An integral design refers to an insulation panel design in which there is only a single component that can only be separated by destroying it. The component is made from a single original piece and / or a single original mass (plastic melt), which in turn is necessarily integral. Internal cohesion is achieved (exclusively) by adhesion and / or cohesion. In this case, a one-piece material (adhesive) coating, etc., may also be present.

[0027] An anode fluid bypass can be provided in the insulation plate, leading from the anode inlet port to the anode outlet port. Furthermore, a cathode fluid bypass can be provided in the insulation plate, leading from the cathode inlet port to the cathode outlet port. Furthermore, the anode fluid bypass and the cathode fluid bypass can be arranged crosswise or without crossings in the insulation plate.

[0028] The fuel cell stack according to the invention comprises a plurality of membrane electrode devices and a plurality of bipolar plates, which alternate with one another in an actual cell stack of the fuel cell stack. A fluid bypass is provided at an anode-side and / or cathode-side longitudinal end in the fuel cell stack, away from a bipolar plate, between at least one supply path and an associated exhaust path of the fuel cell unit. The fluid bypass can be provided on / in a stack housing, on / in an insulation plate, and / or on / in an end plate of the fuel cell stack.

[0029] At least at the upstream beginning of the fluid bypass, a sealing film can protrude from the fluid bypass and, if applicable, from a water trap of the fluid bypass. A sealing film, e.g., a PEN film (PEN: polyethylene naphthalate, is already used, for example, in sealing sleeves (sub-gaskets) of membrane electrode assemblies), can be glued to the insulation plate in the area of ​​its plate base. This film should be sealed primarily around the ports and the fluid bypass. To capture the product water from the inlet port, the sealing film can protrude beyond the port wall of the insulation plate by, for example, approximately 0.5 mm. This allows a film of product water on the port wall and condensed droplets in an edge area of ​​the port wall to be captured.

[0030] What was said above in the context of the insulation plate for the fluid bypass or fluid line (throttling cross-section, hydraulically effective cross-section, etc.) is of course also applicable here analogously, away from the insulation plate. The fuel cell stack does not have a dummy cell directly on an anode-side and / or cathode-side end plate or directly on both end plates. Furthermore, it is preferred that the fuel cell stack does not have a dummy cell. Furthermore, the fuel cell stack can be designed as a fuel cell stack with or without flat gaskets. The insulation plate can be designed as an insulation plate according to the invention.

[0031] Short description of the characters

[0032] The invention is explained in more detail below using exemplary embodiments with reference to the attached schematic and not-to-scale drawing. In the invention, a feature can be configured positively, i.e., present, or negatively, i.e., absent. In this specification, a negative feature is not explicitly explained as a feature unless it is important for the invention to be absent. This means that the invention actually made, and not one constructed by the prior art, consists in omitting this feature. The absence of a feature (negative feature) in an exemplary embodiment indicates that the feature may be optional (to a person skilled in the art). - In the merely exemplary figures (Fig.) of the drawing show:

[0033] Fig. 1 shows a highly simplified block diagram of an embodiment of a fuel cell unit for a fuel cell system of a fuel cell vehicle, Fig. 2 shows a broken-away, sectional and schematic view of a fuel cell stack which is greatly reduced in terms of its individual cells and has a first embodiment of a fluid bypass according to the invention, Fig. 3 shows a schematic view of an insulation plate which is shown in section in the region of one of its inlet connections and a second embodiment of a fluid bypass according to the invention, and Figs. 4 to 6 each show a perspective view of an insulation plate for a fuel cell stack, wherein the insulation plate each shows an embodiment of a fluid bypass according to the invention.

[0034] Embodiments of the invention

[0035] The invention is explained in more detail using an insulation plate 100—see Figs. 2 to 6 with embodiments one to five of the invention—for a fuel cell stack 10 of a fuel cell unit 1, in particular for a low-temperature polymer electrolyte fuel cell system of a fuel cell vehicle, i.e., a motor vehicle having a fuel cell or a fuel cell system. The drawing shows only those sections of the fuel cell system that are necessary for understanding the invention.

[0036] Although the invention is described and illustrated in detail by preferred embodiments, the invention is not limited to the disclosed embodiments. Other variations may be derived therefrom without departing from the scope of the invention. In particular, the invention can also be applied to another mobile or stationary fuel cell unit 1 or fuel cell system.

[0037] Fig. 1 shows a schematic diagram of a fuel cell assembly 1 according to one embodiment, comprising at least one, in particular a plurality of, electrochemical individual fuel cells 11 (individual cells 11) bundled into a fuel cell stack 10, which are housed in a preferably fluid-tight stack housing 16. Each individual cell 11 comprises an electrode chamber 12 designed as an anode chamber 12 and an electrode chamber 13 designed as a cathode chamber 13, which are spatially and electrically separated from one another by a membrane of a membrane electrode device 15.

[0038] A membrane electrode assembly 15 comprises a membrane, two electrodes, and preferably two transport layers, with at least one electrode being provided on the membrane and / or at least one electrode being provided on a transport layer opposite the membrane. Of course, both electrodes can also be provided on the membrane (membrane electrode assembly) or on the transport layers. The membrane or the membrane electrode assembly is preferably arranged in a sealing sleeve ((sub-)gasket), against which a bipolar plate 14 can be sealingly brought into contact. The respective transport layer is arranged in the fuel cell stack 10 in a respective anode compartment 12 or cathode compartment 13.

[0039] A bipolar plate 14 is arranged between each two directly adjacent membrane electrode devices 15, 15, including a respective anode chamber 12 and a respective cathode chamber 13. The bipolar plate 14 serves, among other things, to guide operating media 3, 5 into an anode chamber 12 of a first individual cell 11 and a cathode chamber 13 of a directly adjacent second individual cell 11, as well as to discharge the exhaust gas media 4, 6 generated therein. Furthermore, the bipolar plate 14 establishes an electrically conductive connection between these two individual cells 11, 11 and imparts mechanical stability to the fuel cell stack 10.

[0040] The cathode chambers 13 and, if applicable, their common inflow area or their electrodes form a cathode 39 of the fuel cell stack 10. And the anode chambers 12 and, if applicable, their common inflow area or their electrodes form an anode 29 of the fuel cell stack 10. - To supply the fuel cell stack 10 with its actual operating media 3 (anode operating medium, actual fuel), 5 (cathode operating medium, usually air), the fuel cell unit 1 has an anode supply 20 (operating medium supply 20) and a cathode supply 30 (operating medium supply 30).The anode supply 20 comprises in particular: a fuel reservoir 23 for the anode operating medium 3 (flowing in); an anode supply path 21 with a pressure reducer, a shut-off valve and / or a metering valve 27 (for example) and a jet pump 24 (jet pump 24, ejector 24); an anode exhaust gas path 22 for an anode exhaust gas medium 4 (flowing out, usually into the environment 2); preferably a fuel recirculation path 25 with a fluid conveying device 26 located therein, e.g., a hydrogen recirculation blower 26; optionally, a water separator and optionally, a water tank.

[0041] The cathode supply 30 comprises in particular: a cathode supply path 31 for the cathode operating medium 5 (flowing in, usually from the environment 2), preferably with a fluid conveying device 33; a cathode exhaust gas path 32 for a cathode exhaust gas medium 6 (flowing out, usually into the environment 2), preferably with a turbine 34, in particular for the fluid conveying device 33; preferably a humidity exchanger 36, in particular a gas-to-gas humidifier 36; optionally a cathode-side stack bypass 35 (wastegate 35) between the cathode supply path 31 and the cathode exhaust gas path 32, with a bypass valve 37; optionally a water separator and optionally a water tank.

[0042] The fuel cell unit 1 further comprises, in particular, a cooling medium supply 40 of a thermal system, in particular of the fuel cell vehicle, through which the fuel cell stack 10 can be integrated into a cooling circuit for temperature control, preferably by means of its bipolar plates 14 (cooling medium path 43). The cooling medium supply 40 comprises a cooling medium inlet path 41 and a cooling medium outlet path 42. The cooling medium 7 (inflowing) and 8 (outflowing) circulating in the cooling medium supply 40 are preferably conveyed by means of at least one cooling medium conveying device 44.

[0043] In addition to the fuel cell unit 1, the fuel cell system comprises peripheral system components, such as a control unit, which may be one of the fuel cell vehicle itself. During operation of a fuel cell stack 10 according to the prior art, under certain operating conditions, a first upstream individual cell 11 may become flooded with product water in the anode chamber 12 there and / or in the cathode chamber 13, which usually follows directly in the direction of flow (a reversal in a fuel cell stack 10 is of course possible). This is particularly critical on the anode side due to the risk of fuel starvation and / or another functional problem. However, this should also be avoided on the cathode side in order to ensure the function of an active surface of the lowest individual cell 11.

[0044] To avoid this, in the prior art, one or two electrochemically inactive dummy cells (not shown in the drawing) are inserted upstream of an active cell stack in the fuel cell stack 10. Anode gas and, separately, cathode gas are conducted via these dummy cells as a 'gas short circuit' from the dummy cell inlets to the dummy cell outlets. - Due to the arrangement away from the active cell stack, condensed droplets and product water, which is present inside a port wall of an inlet connection (123, 125; see Figs. 4 to 6) and an inlet port (113, 115; see Figs. 4 to 6) of an insulation plate (100, see Figs. 4 to 6) of the fuel cell stack 10, can be conducted directly to the dummy cell outlets by means of the dummy cells.

[0045] This is facilitated by sealing collars or (sub)gaskets protruding at the inlet ports. The protrusion (151, see Fig. 2) is fundamentally necessary to prevent an electrical short circuit between directly adjacent bipolar plates 14, 14 due to positioning errors of the bipolar plates 14 and the membrane electrode devices 15. The protrusion of approximately 0.5 mm creates an obstacle / back pressure for fluid flow and, above all, for any moisture present in the fluid flow. A problem is that constructing the fuel cell stack 10 using these dummy cells is very complex, since additional inactive membrane electrode devices and special bipolar plates must be installed.

[0046] Figs. 2 to 6 show solutions according to the invention, which are implemented by means of the insulation plate 100. The insulation plate 100 has the task of supplying and disposing of the fuel cell stack 10 with / from its media 3, 4, 5; 6, 7, 8. The insulation plate 100 is essentially divided into two sections: on the one hand, the plate base 101 and, on the other hand, the end plate recess 102 within the plate base 101. When the insulation plate 100 is installed, an upstream end plate of the fuel cell stack 10 is received in the end plate recess 102.

[0047] Aside from the end plate recess 102, the plate base 101 (see Figs. 4 to 6) comprises, on the one hand, an anode inlet connection 123 for an anode operating medium inlet, a cathode outlet connection 126 for a cathode exhaust medium return, and a cooling medium outlet connection 128 for a cooling medium return. On the other hand, the plate base 101 comprises an anode outlet connection 124 for an anode exhaust medium return, a cathode inlet connection 125 for a cathode operating medium inlet, and a cooling medium inlet connection 127 for a cooling medium inlet. A different distribution of the fluid connections 123, 126, 128; 124, 125, 127 is of course possible depending on the requirements of the fuel cell stack 10.

[0048] Here, all fluid connections 123, 126, 128; 124, 125, 127 protrude from a large-area side of the insulation plate 100 in the region of its plate base 101, wherein the plate base 101 opens on the opposite large-area side of the insulation plate 100 with its respective fluid connection 123, 126, 128; 124, 125, 127 relative to the fuel cell stack 10. This means that the respective fluid connection 123, 126, 128; 124, 125, 127 has openings 113, 116, 118; 114, 115, 117. In detail, these are an anode inlet port 113 for the anode operating medium 3, a cathode outlet port 116 for the cathode exhaust gas medium 6, a cooling medium outlet port 118 for the outflowing cooling medium 8, an anode outlet port 114 for the anode exhaust gas medium 4, a cathode inlet port 115 for the cathode operating medium 5, and a cooling medium inlet port 117 for the inflowing cooling medium 7.

[0049] In order to prevent flooding of at least one upstream first individual cell 11 with product water (of course also condensed droplets, steam) in an anode chamber 12 there and / or in a cathode chamber 13 possibly arranged behind it, the fuel cell stack 10 and / or the insulation plate 100 has a fluid bypass 130, i.e. an anode fluid bypass 130, 133 and / or a cathode fluid bypass 130, 135, between at least one supply path 21, 31 and an associated exhaust gas path 22, 32 of the fuel cell unit 1 (see also above). The fluid bypass 130; 133 135 is preferably designed as a fluid line 131, 132, but can also be realized by a flow field or the like.

[0050] In embodiments, the fluid bypass 130; 133, 135 is particularly arranged in the plate base 101 of the insulation plate 100 and runs therein entirely or partially as a groove 131 and / or entirely or partially as a through-hole 132. Of course, the fluid bypass 130; 133, 135 can also run partially through a fluid connection 123, 126; 124, 125, originate from such a connection, and / or open into such a connection. A flow direction of a respective fluid, i.e., among other things, of product water present on the anode side and / or the cathode side, is illustrated by an arrow in Figs. 2 to 6.

[0051] Furthermore, it is preferred to install a water trap 140; 143, 145 (see also above) on the anode side (143) and / or cathode side (145), particularly upstream, by means of which product water (condensed droplets) can be captured upstream of the fluid bypass 130; 133, 135 and directed thereto. It is of course also possible to provide such a water trap 140; 143, 145 downstream at / in the respective outlet port 114, 116 or at / in the respective outlet connection 124, 126.

[0052] Preferably, a fluid bypass 130; 133, 135 in fluid communication with the insulation plate 100 or its plate base 101 is provided at at least one port 113, 115; 114, 116, and preferably also a water trap 140; 143, 145 in fluid communication therewith, which together capture the excess product water (including condensed droplets, steam, and a small portion of any recirculating operating medium 3) and direct it from the inlet port 113, 115 to the outlet port 114, 116.

[0053] This can be easily achieved in fuel cell stacks 10 without flat gaskets. In such cases, a recess 140, 143 (water trap 140, 143) can be created around an anode inlet port 113 and optionally also around an anode outlet port 114, e.g., by injection molding the insulation plate 100. This radial recess 140, 143 around the anode inlet port 113 is connected to a channel 130, 133 (groove 131 of the fluid bypass 130, 133), which is also created using an injection molding tool (see Figs. 4 to 6) and leads to the anode outlet port 114 or the recess 140, 143 therein. This can also be realized analogously on the cathode side (see Figs. 5 and 6).

[0054] A sealing film 150, in particular a PEN film 150, is preferably glued to the insulation plate 100 (see Fig. 2). This sealing film 150 must be sealed, especially around all ports 113, 116, 118; 114, 115, 117 and the channel (groove 131 of the fluid bypass 130; 133, 135). To ensure that the product water from the inlet port 113, 115 can be captured, the sealing film 150, analogous to a sealing sleeve of a membrane electrode device 15, should protrude approximately 0.5 mm beyond a port wall of the insulation plate 100 (projection 151). This allows a water film on the port wall, condensed water droplets, and vapor to be captured at an edge area.

[0055] In fuel cell stacks 10 with flat gaskets 157, this can be implemented similarly, but with an additional bore or a slider tool using an injection molding tool (see Fig. 3). In this case, the water trap 140; 143, 145 is located, for example, as a circumferential ring 140; 143, 145 or a channel 140; 143, 145 along a geometry of the inlet port 113, 115 upstream of a projection, which can, for example, be injection-molded or realized by means of an inserted or bonded insert 155.

[0056] In the outlet ports 114, 116, only a bore (through-hole 132 of the fluid bypass 130, 133) is required, or a closed channel (through-hole 132 of the fluid bypass 130, 133) created using a slide mold during injection molding. This ensures fluid communication between the open channel 130; 133, 135 (groove 131 of the fluid bypass 130; 133, 135) in the plate base 101 and the outlet port 114, 116, and the flat gasket is tunneled under.

[0057] If, in addition to a water trap 140, 143 at / in the anode inlet port 113, a water trap 140, 145 is also required in the cathode inlet port 115, this is possible, for example, if the cathode-side fluid bypass 130, 133 tunnels under the anode-side fluid bypass 130, 135 (see Fig. 5). This can be easily implemented by means of a bore (through-hole 132 of the fluid bypass 130, 135) or a slide tool (through-hole 132 of the fluid bypass 130, 135) during injection molding.

[0058] As a further embodiment, one of the fluid bypasses 130; (133), 135 can be routed around the respective ports 113, (116), 118; (114), (115), (117) (see Fig. 6). In such a case, tunneling can be avoided. - The guides of the fluid bypasses 130; 133, 135 shown in Figs. 4 to 6 can in turn be sealed with the sealing film 150, which is sealingly bonded to the insulation plate 100.

Claims

Claims 1. Insulation plate (100) for a fuel cell stack (10) of a fuel cell unit (1), preferably for a fuel cell vehicle, with a plate base (101), wherein an anode inlet port (113) and an anode outlet port (114) associated therewith, as well as a cathode inlet port (115) and a cathode outlet port (116) associated therewith are arranged in the plate base (101), characterized in that a fluid bypass (130; 133, 135) is arranged in the insulation plate (100) between at least one inlet port (113, 115) and at least one associated outlet port (114, 116), through which fluid bypass the inlet port (113, 115) is brought into fluid communication with the associated outlet port (114, 116).

2. Insulation plate (100) according to the preceding claim, characterized in that: • the fluid bypass (130; 133, 135) is arranged in the plate base (101) and apart therefrom in the insulation plate (100) or exclusively in the plate base (101), • the fluid bypass (130; 133, 135) has a throttling cross-section at least at one point, in sections or substantially over its entire extent, and / or • a hydraulically effective cross-section of the fluid bypass (130; 133, 135) corresponds approximately to that of an anode-side or cathode-side flow field of a bipolar plate (14), preferably including a distribution field.

3. Insulation plate (100) according to one of the preceding claims, characterized in that the fluid bypass (130; 133, 135) is designed in sections or substantially completely as a fluid line (130; 133, 135), wherein the fluid line (130; 133, 135) has at least or exactly one a fluid path for an anode operating medium (3) or a cathode operating medium (5) of the fuel cell stack (10).

4. Insulation plate (100) according to one of the preceding claims, characterized in that the fluid line (130; 133, 135): • is designed as a narrow, throttling fluid line (130; 133, 135) over a main or substantially entire extent, • is designed at least in sections as a groove (131) open on one side in the circumferential direction and / or a through-recess (132) completely closed in the circumferential direction, and / or • has a polygonal, V-shaped, rectangular, U-shaped or elliptical cross-section at least in sections or substantially over its entire extent.

5. Insulation plate (100) according to one of the preceding claims, characterized in that the plate base (101) has a water trap (140; 143, 145) at the inlet port (113, 115) and / or at the outlet port (114, 116), wherein the water trap (140; 143, 145) is arranged in the plate base (101) at least partially running around the port (113, 115; 114, 116) and / or is provided on / in the port (113, 115; 114, 116) at least partially running around the port (113, 115; 114, 116).

6. Insulation plate (100) according to one of the preceding claims, characterized in that the fluid bypass (130; 133, 135): • is arranged in sections or exclusively as a groove (131) from the inlet port (113, 115) to the associated outlet port (114, 116), • is designed in sections as a through-hole (132) leading away from the inlet port (113, 115) and / or opening into the outlet port (114, 116), and / or • is designed in sections as a recess that can be delimited by a second component of the fuel cell stack (10).

7. Insulation plate (100) according to one of the preceding claims, characterized in that the insulation plate (100) has at least or exactly two fluid bypasses (130, 133; 130, 135), wherein: • the fluid bypasses (130, 133; 130, 135) are arranged in the insulation plate (100) so as to be fluid-mechanically separated from one another over their entire extent, and / or • an intersection of the fluid bypasses (130, 133; 130, 135) is designed such that in the region of the intersection, one fluid bypass is arranged above the other fluid bypass (130, 135 / 133) in the plate base (101), • two fluid bypasses (130, 133; 130, 135) are arranged laterally next to an end plate recess (101) lying parallel to one another in the plate base (101).

8. Insulation plate (100) according to one of the preceding claims, characterized in that: • a smallest cross-section of the fluid bypass (130; 133, 135) approx.: 1 ,25mm 2 , 1 ,5mm 2 , 1 ,75mm 2 , 2.0mm 2 , 2.25mm 2 , 2.5mm 2 , 2.75mm 2 , 3mm 2 or 3.25mm 2 is ±10% each, • in the plate base (101), preferably between ports (113, 116, 118 & 114, 115, 117) arranged therein on both sides, the end plate recess (102) for an end plate of the fuel cell stack (10) is arranged, and / or • inlet connections (123, 125, 127) for inflowing media (3, 5, 7) of the fuel cell stack (10) and outlet connections (124, 126, 128) for outflowing media (3, 5, 7) of the fuel cell stack (10) are formed on the plate base (101).

9. Insulation plate (100) according to one of the preceding claims, characterized in that: • in the insulation plate (100) an anode fluid bypass (130, 133) leads from the anode inlet port (113) to the anode outlet port (114), • in the insulation plate (100) a cathode fluid bypass (130, 135) leads from the cathode inlet port (115) to the cathode outlet port (116), and / or the anode fluid bypass (130, 133) and the cathode fluid bypass (130, 135) are arranged crosswise or without crossing in the insulation plate (100).

10. Fuel cell stack (10) for a fuel cell unit (1), preferably for a fuel cell vehicle, with a plurality of membrane electrode devices (15) and a plurality of bipolar plates (14) which alternate with one another in an actual cell stack of the fuel cell stack (10), characterized in that a fluid bypass (130; 133, 135) is arranged at an anode-side and / or cathode-side longitudinal end in the fuel cell stack (10) away from a bipolar plate (14) between at least one supply path (21, 31) and an associated exhaust gas path (22, 32) of the fuel cell unit (1).

11. Fuel cell stack (10) according to the preceding claim, characterized in that: • the fluid bypass (130; 133, 135) is arranged on / in a stack housing (16), on / in an insulation plate (100) and / or on / in an end plate of the fuel cell stack (10), • at least at an upstream beginning of the fluid bypass (130; 133, 135) a sealing film (150) protrudes (151) on the fluid bypass (130; 133, 135) and optionally on a water trap (140) of the fluid bypass (130; 133, 135), and / or • the insulation plate (100) is designed as an insulation plate (100) according to one of the preceding claims.

12. Fuel cell unit (1), fuel cell system or fuel cell vehicle, characterized in that the fuel cell unit (1), the fuel cell system or the fuel cell vehicle is designed with an insulation plate (100) for a fuel cell stack (10) according to one of the preceding claims and / or has a fuel cell stack (10) according to one of the preceding claims.

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