Bipolar plate for a fuel cell device

Abstract

The present invention relates to a bipolar plate (100) for a fuel cell device, comprising: at least one bipolar plate layer (102), on which there are provided a plurality of flow channels (104), in particular adjacently arranged, flow channels, along which a fluid medium, in particular an operating gas of the fuel cell device, can be passed along a flow direction (106), wherein multiple flow channels (104), preferably all the flow channels, have channel depths (116) which vary along the flow direction (106), wherein each flow channel (104) with a varying channel depth (116) has a plurality of first and second regions (118, 120), the first regions (118) having a first channel depth (122) and the second regions (120) having a second channel depth (124), and the first and the second regions (118, 120) are provided in alternating sequence along the flow direction (106), and wherein the second channel depths (124) in the second regions (120) decrease along the flow direction (106).

Description

[0001] Bipolar plate for a fuel cell device

[0002] The present invention relates to a bipolar plate for a fuel cell device.

[0003] Furthermore, the present invention relates to a bipolar plate arrangement for a fuel cell device and a fuel cell device with a bipolar plate and / or a bipolar plate arrangement.

[0004] Bipolar plates are generally known in the art and serve, among other things, to guide gas along an electrochemically active region of a fuel cell device, in particular an electrochemically active region of a membrane electrode assembly. For this purpose, several channels are typically provided in the bipolar plate, forming a flow field along the electrochemically active region. In such a flow field, local conditions along a gas flow path are generally not specifically taken into account. Examples of such conditions include, in particular: a decreasing partial pressure of oxygen towards the end of the flow field, and / or different and / or decreasing gas flow velocities along the length of the aforementioned channels, and / or different and / or decreasing flow velocities from channel to channel, and / or the presence of liquid water.All of this can have a particularly detrimental effect on achieving a homogeneous distribution of gas and / or a uniform supply of gas to the electrochemically active area.

[0005] The present invention is based on the objective of providing a bipolar plate for a fuel cell device which preferably enables improved flow behavior of operating gases and / or gas mixtures and in particular enables improved performance and / or improved efficiency of a fuel cell device in which such a bipolar plate can be used.

[0006] This problem is solved according to the invention by the features of the independent claim. Advantageous embodiments are described in the dependent claims.

[0007] A bipolar plate according to the invention for a fuel cell device has at least the following: at least one layer of bipolar plates on which a plurality of, in particular adjacent, flow channels are provided, through which a fluid medium, in particular an operating gas of the fuel cell device, can be guided along a flow direction, wherein several, preferably all, flow channels are provided with channel depths varying along the flow direction, wherein each flow channel provided with a varying channel depth has a plurality of first and second regions, wherein the first regions have a first channel depth and the second regions have a second channel depth, wherein the first and the second regions are provided alternately one after the other along the flow direction, and wherein the second channel depths decrease in the second regions along the flow direction.

[0008] The fluid medium may be a gas and / or a gas mixture. The gas and / or gas mixture may preferably be the operating gas of the fuel cell device. The operating gas may be an anode gas and / or a cathode gas. The anode gas may preferably be a fuel gas, for example, hydrogen, and / or the cathode gas may preferably be an oxidizing agent, for example, oxygen or air.

[0009] It may be provided that the multitude of flow channels form at least one flow field for the fluid medium.

[0010] It may be provided that the bipolar plate arrangement is an anode-side bipolar plate arrangement or a cathode-side bipolar plate arrangement.

[0011] The bipolar plate may be provided to have at least one further bipolar plate layer, wherein the bipolar plate layer and the further bipolar plate layer are arranged and / or attached to one another. For example, the bipolar plate layer and the further bipolar plate layer may be arranged and / or attached to one another along a longitudinal median plane.

[0012] It may be provided that one of the bipolar plate layers is designed as an anode-side bipolar plate layer and the other of the bipolar plate layers is designed as a cathode-side bipolar plate layer.

[0013] For example, it may be provided that the additional bipolar plate layer is designed like the bipolar plate layer described herein, so that reference can be made to the corresponding description of the bipolar plate layer, or that the additional bipolar plate layer and the bipolar plate layer are designed differently. It may be provided that a membrane electrode assembly, in particular a gas diffusion layer, can be arranged and / or mounted on the bipolar plate, and in particular on the bipolar plate layer and / or the additional bipolar plate layer, especially for proper use in the fuel cell device.

[0014] It may be provided that the bipolar plate is particularly suitable for use in a fuel cell device, which preferably has several electrochemical units arranged successively along a stacking direction and preferably each having said bipolar plate.

[0015] For example, the fuel cell device can have several electrochemical units which are arranged sequentially along a stacking direction of the fuel cell device.

[0016] For example, such a fuel cell device can be designed as a polymer electrolyte membrane (PEM) fuel cell device.

[0017] It may be provided that such an electrochemical unit has a membrane electrode arrangement, gas diffusion layers and a sealing arrangement.

[0018] It may be provided that the second channel depths in the second areas are increasingly and / or gradually reduced along the direction of flow.

[0019] For example, it may be provided that a channel depth, in particular a varying channel depth and / or a first channel depth and / or a second channel depth, is oriented transversely and in particular perpendicularly to the flow direction.

[0020] Additionally or alternatively, it may be provided, for example, that a channel depth, in particular a varying channel depth and / or a first channel depth and / or a second channel depth, is oriented transversely and in particular perpendicular to a longitudinal direction of the bipolar plate and transversely and in particular perpendicular to a transverse direction of the bipolar plate.

[0021] Additionally or alternatively, it may be provided, for example, that a channel depth, in particular a varying channel depth and / or a first channel depth and / or a second channel depth, is oriented along the stacking direction of the fuel cell device. For example, it may be provided that each flow channel has at least one channel bottom, wherein a varying channel depth, e.g., the second channel depths, of a flow channel may be provided and / or implemented by means of a channel bottom elevation. For example, the channel bottom may be elevated in the second sections.

[0022] For example, it may be provided that such a channel floor elevation is oriented transversely and in particular perpendicularly to the flow direction and / or transverse direction and / or preferably longitudinally to the stacking direction.

[0023] It may be provided that a locus curve is formed by the varying channel depth, especially along the direction of flow.

[0024] For example, it may be provided that first sections of the locus curve, formed by the first channel depths, each have a minimum and / or a low point of the locus curve and / or are, and / or second sections of the locus curve, formed by the second channel depths, each have a maximum and / or a high point of the locus curve and / or are.

[0025] For example, it may be provided that the maxima and / or high points of the locus curve are arranged along the flow direction essentially on a linear or non-linear, e.g. exponential, curve.

[0026] It may be intended that the first channel depth is an initial channel depth and / or a maximum channel depth.

[0027] Additionally or alternatively, it may be provided that the second channel depth which is furthest from the second channel depths of a flow channel to the beginning of this flow channel is a minimum channel depth.

[0028] It may be provided that the first and second sections are arranged alternately along the direction of flow at regular and / or irregular intervals.

[0029] It can be designed so that the secondary channel depths decrease with increasing distance from the start of a flow channel. For example, the secondary channel depths can be progressively smaller, or reduced, depending on the distance from the start of a flow channel.

[0030] It may additionally or alternatively be provided that several, in particular all, of the second channel depths of a flow channel are different and / or the same.

[0031] For example, several, preferably adjacent, second sections of a flow channel can form a group, e.g., of two or more sections, whose second channel depths are the same, whereby it can be provided, for example, that these second channel depths and equal second channel depths of a group of second sections of this flow channel adjacent to this group are different, e.g., smaller or larger.

[0032] It may additionally or alternatively be provided that the first channel depths of a flow channel are constant over a length of this flow channel, preferably over the entire length of this flow channel.

[0033] For example, the initial channel depths of a flow channel can be the same along the length of that flow channel.

[0034] It may additionally or alternatively be provided that with increasing distance from the start of a flow channel, the initial channel depths in the first areas decrease and / or increase.

[0035] For example, the initial channel depths can be progressively smaller, e.g. reduced, and / or larger, e.g. widened, depending on the distance from the start of a flow channel.

[0036] It may additionally or alternatively be provided that several, in particular all, of the first channel depths of a flow channel are different and / or the same.

[0037] For example, several, preferably adjacent, first sections of a flow channel can form a group, e.g., of two or more sections, whose first channel depths are the same, whereby it can be provided, for example, that these first channel depths and equal first channel depths of a group of first sections of this flow channel adjacent to this group are different, e.g., smaller or larger.

[0038] It may be provided that a decrease in the second channel depths is proportional or disproportionate, preferably depending on an increasing distance from the start of a flow channel.

[0039] For example, it may be provided that a respective geometric center of the relevant second areas, which have the decreasing second channel depths, is arranged along the flow direction essentially on a linear or non-linear, e.g. exponential, curve.

[0040] It may be provided that the channel depths of adjacent second areas differ from each other by between 1% and 60%, in particular between 3% and 50%, preferably between 5% and 35%.

[0041] It may be provided that a slope area and / or a slope area is formed between a first area and a second area.

[0042] In particular, a gradient area can be arranged between a first area and a second area and / or a gradient area can be arranged between a second area and a first area.

[0043] For example, in the direction of flow, a gradient area can be arranged after a first area and / or a gradient area can be arranged before a second area.

[0044] For example, in the direction of flow, a sinking area can be arranged after a second area and / or a sinking area can be arranged before a first area.

[0045] For example, the gradient area can be designed like a ramp and / or form an inflow ramp for the second area with the second channel depth and / or include one.

[0046] For example, the descent zone can be ramp-shaped and / or form an outflow ramp for the second zone with the second channel depth and / or include such a ramp. It can also be designed, for example, that the rising and / or falling zones of a given flow channel shorten depending on the increasing distance from the start of this flow channel along the flow direction.

[0047] For example, it may be additionally or alternatively provided that the slope areas and / or the sink areas of a flow channel in question lengthen depending on an increasing distance from the beginning of this flow channel along the direction of flow.

[0048] For example, it may be additionally or alternatively provided that a slope, in particular a positive slope and / or a negative slope, of the slope areas and / or the sink areas increases depending on an increasing distance from the beginning of a relevant flow channel.

[0049] For example, it may be additionally or alternatively provided that a slope, in particular a positive slope and / or a negative slope, of the slope areas and / or the sink areas decreases depending on an increasing distance from the beginning of a relevant flow channel.

[0050] For example, a negative slope can be understood as an incline.

[0051] For example, a positive slope can be associated with or assigned to an angle of inclination, and / or a negative slope can be associated with or assigned to an angle of inclination.

[0052] For example, an angle of inclination can be in an angular range of 0.5° to 70°, in particular from 1° to 45°, preferably 3° to 30°, and / or an angle of inclination can be in an angular range of 0.5° to 70°, in particular from 1° to 45°, preferably 3° to 30°.

[0053] Additionally or alternatively, an angle of inclination can, for example, be in an angle range of 0.5° to 45°, in particular from 1° to 35°, preferably 2° to 10°.

[0054] It can be provided that the gradients of the slope sections of a flow channel increase with increasing distance from the start of this flow channel. Preferably, it can be provided that the increase in gradients is proportional or disproportionate.

[0055] It may additionally or alternatively be provided that the respective gradients of several, in particular all, gradient sections of a flow channel are different from each other and / or the same.

[0056] It may be provided that the slopes, especially negative slopes, of the sinking areas of a flow channel are increasingly larger depending on an increasing distance from the beginning of this flow channel.

[0057] Preferably, it can be provided that the increase in the slopes is proportional or disproportionate.

[0058] Alternatively, it is also conceivable that the slopes, especially negative slopes, of the sinking areas of a flow channel become increasingly smaller depending on an increasing distance from the beginning of this flow channel.

[0059] It may additionally or alternatively be provided that the respective gradients of several, in particular all, sinking areas of a flow channel are different from each other and / or the same.

[0060] For example, it may be provided that a rising section adjacent to a second section and a falling section adjacent to this second section are of the same length along the flow direction or have different lengths. Preferably, the falling section in question may be longer than the rising section in question.

[0061] For example, it may be provided that a rising section adjacent to a first section and a falling section adjacent to this first section are of the same length along the flow direction or have different lengths. Preferably, the falling section may be longer than the rising section. It may be provided that a tangent located at the geometric center of a first section along the flow direction and another tangent located at the geometric center of a rising section adjacent to the first section along the flow direction are arranged at an angle of 0.5° to 70°, in particular 1° to 45°, preferably 3° to 30°, to each other.

[0062] It may additionally or alternatively be provided that a tangent which lies at a geometric center of a second region along the flow direction, and another tangent which lies at a geometric center of a sinking region adjacent to the second region in question along the flow direction, are arranged at an angle of 0.5° to 45°, in particular from 1° to 35°, preferably 2° to 10°, to each other.

[0063] It may be provided that the distances between second sections of the flow channel decrease with increasing distance from the beginning of the flow channel.

[0064] It may additionally or alternatively be provided that distances between the first sections of the flow channel decrease with increasing distance from the beginning of the flow channel.

[0065] It is also conceivable that distances between second areas or distances between first areas of the flow channel increase with increasing distance from the beginning of the flow channel.

[0066] It may be provided that the flow channels have alternating widening areas and narrowing areas along the flow direction, with widening areas and / or narrowing areas of adjacent flow channels being arranged offset from each other along the flow direction.

[0067] For example, the expansion and narrowing regions of adjacent flow channels can be offset from each other along the flow direction such that an expansion region and a narrowing region of adjacent flow channels are arranged side by side, preferably with respect to one or the transverse direction of the bipolar plate. In particular, the expansion and / or narrowing regions of the flow channels can create a varying channel width for a given flow channel, for example, maximum channel widths and / or minimum channel widths.

[0068] For example, it may be provided that a channel width is oriented transversely and, in particular, perpendicularly to a channel depth and / or the flow direction.

[0069] In particular, it may be provided that an expansion area has a maximum channel width and a narrowing area has a minimum channel width.

[0070] Preferably, a transition arranged in the expansion area from the minimum channel width of the narrowing area to the maximum channel width of the expansion area can be designed to expand proportionally or disproportionately.

[0071] Preferably, it can additionally or alternatively be provided that a transition arranged in the narrowing area from the maximum channel width of the expansion area to the minimum channel width of the narrowing area is designed to be proportionally or disproportionately narrower.

[0072] Preferably, the minimum channel widths of a flow channel can be constant over a length of this flow channel, preferably over the entire length of this flow channel.

[0073] Preferably, the maximum channel widths of a flow channel can be constant over a length of this flow channel, preferably over the entire length of this flow channel.

[0074] It may be provided that each expansion area of ​​a flow channel is equipped with one of the first channel depths.

[0075] Preferably, each expansion area of ​​a flow channel can be provided with one of the first channel depths, particularly where the maximum channel width of the expansion area in question is provided.

[0076] It may additionally or alternatively be provided that each narrowing region of a flow channel is provided with one of the second channel depths. Preferably, each narrowing region of a flow channel may be provided with one of the second channel depths, particularly where the minimum channel width of the narrowing region in question is specified.

[0077] It may be provided that the multitude of flow channels are at least partially bounded by webs, in particular laterally, wherein the webs in the widening areas and / or the narrowing areas of the flow channels have one or more overflow sections, through which an overflow of the fluid medium between adjacent flow channels is made possible.

[0078] In particular, it may be provided that the webs in the expansion areas and / or the narrowing areas of the flow channels have one or more preferred overflow sections, through which an increased overflow of the fluid medium between adjacent flow channels is made possible and which are preferably provided in the area of ​​a maximum channel width of the expansion areas and / or in the area of ​​a minimum channel width of the narrowing areas.

[0079] Increased overflow can be understood, for example, as a stronger overflow in the area of ​​a maximum channel width of the expansion areas and / or in the area of ​​a minimum channel width of the narrowing areas, and / or a higher volume flow rate there than in a respective area with a channel width that deviates from these maximum and / or minimum channel widths.

[0080] It can be provided that the multitude of flow channels are at least partially bounded by webs, in particular laterally, wherein the webs in areas of the first channel depths and / or the second channel depths of the flow channels have one or more, in particular preferred, overflow sections, via which an, preferably enhanced, overflow of the fluid medium between adjacent flow channels is made possible.

[0081] Increased overflow can be understood, for example, as a stronger overflow in the area of ​​the first channel depths and / or the second channel depths, and / or a higher volume flow rate there than in a respective area with a channel depth that differs from these first and / or second channel depths. For example, it may be provided that the expansion areas and / or the narrowing areas are essentially formed by the webs.

[0082] For example, the ribs may have an essentially wave-like shape, especially in a top view, for example in a view in the stacking direction and / or in the direction along the channel depths.

[0083] For example, adjacent bridges, between which a flow channel is arranged and which limit it, especially laterally, can have an axially symmetric course, for example axially symmetric with respect to a common line running along the flow channel between them.

[0084] It may be provided that the webs are formed from at least one layer of bipolar plates; preferably formed from this layer, molded onto it and / or inserted into it.

[0085] It may be provided that at least partially flat support sections are formed on the upper sides of the webs, through which the bipolar plate can be supported against an adjacent, further bipolar plate of a fuel cell device.

[0086] Advantageously, the expansion and narrowing zones and / or the first and second channel depths in the flow direction of each flow channel can provide a defined variation in the flow cross-section for the fluid medium. This allows, for example, the pressure and / or flow velocity of the fluid medium in the flow channels, and thus in the flow field formed by the flow channels, to be adjusted and / or set. Advantageously, this can enable an improved and / or more uniform supply and / or distribution of the fluid medium to and / or at an electrochemically active area, e.g., a membrane electrode assembly or a fuel cell device.

[0087] Advantageously, the design and / or arrangement of the expansion and narrowing zones and / or the first and second channel depths allows for targeted consideration of local conditions along a respective flow channel, i.e., the flow path of the fluid medium. This can preferably prevent (i) decreasing partial pressures towards the end of the flow field, and / or (ii) different and / or decreasing flow velocities of the fluid medium along the length of said flow channels, and / or (iii) different and / or decreasing flow velocities from one flow channel to the next. Advantageously, this can enable a more homogeneous distribution of the fluid medium and / or a uniform supply of fluid medium to the electrochemically active area of ​​a fuel cell device.

[0088] Advantageously, channel floor elevations or the second areas in the flow channels, through which the second channel depths can be realized and which, as described herein, can be of varying intensity depending on the position in the flow channel and thus in the flow field, can enable a varying flow cross-section adaptation.

[0089] Advantageously, the aforementioned channel floor elevations in the flow channels allow static pressure differences between channel constrictions, here the narrowing areas (high flow velocity), and wide channel areas, here the widening areas (low flow velocity), to be locally adjusted and / or influenced differently, in particular for the targeted increase, for example maximization, of the overflow of the fluid medium between adjacent flow channels over the webs, preferably at the, in particular preferred, overflow sections.

[0090] Furthermore, it is advantageous to enable varying flow cross-section adaptation by using different ramp angles or slope angles in the inflow area, here slope area, of the channel bottom elevations in the flow channels, which, as described herein, can be of varying intensity depending on the position in the flow channel and thus in the flow field.

[0091] Furthermore, by using different ramp angles or slope angles in the inflow area (here, slope area) of the channel bottom elevations, a flow impulse design can be created that is adapted to the specific position in the respective flow channel or flow field, directing the flow towards the electrochemically active area of ​​the fuel cell device. Advantageously, this can be achieved while simultaneously minimizing the impact on flow pressure loss in the respective flow channel or flow field and / or can enable and / or support improved cross-flow of the fluid medium from one flow channel to another. Additionally or alternatively, different ramp angles or slope angles can advantageously be used to...The angle of inclination in the outflow area, here the sinking area, of the channel floor elevations in the flow channels, which, as described herein, can be of varying intensity depending on the position in the flow channel and thus in the flow field, may enable a varying flow cross-section adjustment.

[0092] It may be provided that the present invention further provides a bipolar plate arrangement for a fuel cell device.

[0093] Preferably, the bipolar plate arrangement may include at least one bipolar plate, which may preferably be configured as described above and / or below, and at least one gas diffusion layer, which is arranged on the bipolar plate and in particular on a bipolar plate layer of the bipolar plate.

[0094] All structural and functional features associated with the previously described bipolar plate and / or its embodiments can also be included in the bipolar plate arrangement according to the invention, either alone or in combination, and the associated properties, configurations, and advantages can accordingly also be included and achieved. It is further understood that the reverse is also true.

[0095] It may be provided that the present invention further provides a fuel cell device.

[0096] Preferably, the fuel cell device may have at least one bipolar plate, which may preferably be configured as described above and / or below, and / or at least one bipolar plate arrangement, which may preferably be configured as described above and / or below.

[0097] All structural and functional features associated with the previously described bipolar plate and / or its embodiments can also be included in the fuel cell device according to the invention, either individually or in combination, and the associated properties, configurations, and advantages can accordingly be included and achieved. It is further understood that the reverse is also true. The fuel cell device can be particularly suitable for a motor vehicle.

[0098] It is understood that the present invention may further relate to a vehicle, in particular a motor vehicle, wherein the vehicle may have the fuel cell device described herein.

[0099] The motor vehicle can be, for example, a road vehicle, a watercraft or a rail vehicle.

[0100] Further preferred features and / or advantages of the present invention are the subject of the following description and the graphic representation of exemplary embodiments.

[0101] The drawings show:

[0102] Fig. 1 shows a schematic side sectional view of a bipolar plate for a fuel cell device according to an exemplary embodiment of the present invention; and

[0103] Fig. 2 is a schematic top view of the bipolar plate from Fig. 1.

[0104] Identical or functionally equivalent elements are provided with the same reference symbols in all figures.

[0105] Referring to Figs. 1 and 2, a bipolar plate 100 for a fuel cell device according to an exemplary embodiment of the present invention is shown schematically.

[0106] The bipolar plate 100 has at least one bipolar plate layer 102.

[0107] Bipolar plate layer 102 is, for example, an anode-side bipolar plate layer or a cathode-side bipolar plate layer.

[0108] The bipolar plate 100 can further comprise another bipolar plate layer not shown in the figures, wherein the bipolar plate layer 102 and this further bipolar plate layer are preferably arranged adjacent to one another and / or attached to one another. It is understood that preferably one of the bipolar plate layers is configured as an anode-side bipolar plate layer and the other of the bipolar plate layers is configured as a cathode-side bipolar plate layer.

[0109] The bipolar plate layer 102 has a plurality of flow channels 104 running side by side. For descriptive purposes, four adjacent flow channels 104 are shown schematically in Fig. 2 as an example.

[0110] A fluid medium, which in this case is an operating gas of a fuel cell device, can be guided through the flow channels 104 along a flow direction 106.

[0111] The gas in question, or operating gas, is, for example, an anode gas or a cathode gas. The anode gas can preferably be a fuel gas, such as hydrogen, and the cathode gas can preferably be an oxidizing agent, such as oxygen or air.

[0112] The flow channels 104 are preferably formed from the bipolar plate layer 102, in particular they are formed from it, molded onto it or incorporated into it.

[0113] The flow channels 104 form a flow field 108 for the operating gas.

[0114] When the bipolar plate 100 is used in a fuel cell device, the corresponding operating gas can be supplied to the fuel cell device via the flow channels 104 and in particular the flow field 108 of an associated membrane electrode unit, in particular via a gas diffusion layer 110, and thus to the electrochemically active area of ​​the fuel cell device.

[0115] As can be seen in Fig. 1, the said gas diffusion layer 110 of a fuel cell device can be arranged and mounted on the bipolar plate 100 and in particular on the bipolar plate layer 102.

[0116] The flow channels 104 are each bounded to each other by webs 112 (see Fig. 2).

[0117] The webs 112 are preferably formed from the bipolar plate layer 102, in particular they are formed from, molded onto, or embedded in it. In particular, each flow channel 104 is laterally bounded at least partially by webs 112 and furthermore has a channel bottom 114, via which the webs 112 are connected to one another.

[0118] Thus, each flow channel 104 is preferably formed by lateral webs 112 and the channel floor 114.

[0119] As can be seen from Fig. 1, the flow channels 104 are provided with channel depths 116 that vary along the flow direction 106.

[0120] A channel depth 116, 122, 124 is oriented transversely and preferably perpendicularly to the flow direction 106. Furthermore, a channel depth 116, 122, 124 is oriented transversely and preferably perpendicularly to a longitudinal direction of the bipolar plate 100 and transversely and preferably perpendicularly to a transverse direction of the bipolar plate 100.

[0121] Each flow channel 104 with varying channel depth 116 has a plurality of first areas 118 and second areas 120.

[0122] The first and second sections 118, 120 are arranged alternately along the flow direction 106.

[0123] The first areas 118 have a first channel depth of 122 and the second areas 120 have a second channel depth of 124.

[0124] The first channel depths 122 of the flow channels 104 are constant and equal in the present embodiment, preferably over the entire lengths of the flow channels 104.

[0125] The first channel depths 122 thus form an initial channel depth and / or a maximum channel depth of the flow channels 104.

[0126] The second channel depths 124 are less, or less deep, than the first channel depths 122.

[0127] For example, the second channel depths 124 of a flow channel 104 are provided and / or realized by means of raising the channel floor 114. As shown in Fig. 1, the channel floor 114 is raised in the second sections 120 compared to the first sections 118 to enable the second channel depths 124.

[0128] Furthermore, the second channel depths 124 decrease in the second areas 120 along the flow direction 106. For example, the second channel depths 124 in the second areas 120 along the flow direction 106 are increasingly and / or gradually reduced.

[0129] The said channel floor elevations of the channel floor 114 and / or amounts of the said channel floor elevations of the channel floor 114 increase along the flow direction 106 in order to allow the decreasing second channel depths 124 respectively.

[0130] As can be seen in Fig. 1 from the sectioned course of the channel bottom 114, a locus curve can be formed by the varying channel depth 116 along the flow direction 106, wherein first sections of the locus curve, formed by the first channel depths 122, each have a minimum and / or a low point of the locus curve, and second sections of the locus curve, formed by the second channel depths 124, each have a maximum and / or a high point of the locus curve.

[0131] The aforementioned maxima and / or high points of the locus curve are arranged along the flow direction 106 essentially on an imaginary, linear curve or line.

[0132] A respective geometric center of the relevant second areas 120, which exhibit the decreasing second channel depths 124 (or the maxima and / or high points of the locus curve), are arranged along the flow direction 106 essentially on an imaginary, linear curve or line.

[0133] For example, a decrease in the second channel depths 124 is proportional depending on an increasing distance from the beginning of a flow channel 104.

[0134] With increasing distance from the start of a flow channel 104, the second channel depths 124 decrease in the second areas 120.

[0135] In the present embodiment, all of the second channel depths 124 of a respective flow channel 104 are different from one another. For example, the second channel depths 124 of adjacent second areas 120 differ from one another by between 1% and 60%, for example between 3% and 50%, for example between 5% and 35%.

[0136] Furthermore, an increase in the said channel floor elevations of the channel floor 114 and / or the amounts of the said channel floor elevations of the channel floor 114 is proportional depending on the increasing distance from the beginning of a flow channel 104.

[0137] It is understood that the second channel depth 124 which is furthest from the beginning of a flow channel 104 is a minimum channel depth. In Fig. 1, for example, this is the second channel depth 124 shown furthest to the right.

[0138] The first and second sections 118, 120 are provided alternately at irregular intervals along the flow direction 106.

[0139] Between each first area 118 and each second area 120, a gradient area 126 and / or a descent area 128 is formed.

[0140] In particular, a slope area 126 is arranged between a first area 118 and a second area 120 and a slope area 128 is arranged between a second area 120 and a first area 118.

[0141] In the direction of flow 106, a gradient area 126 is arranged after a first area 118 and before a second area 120.

[0142] A sinking area 128 is arranged in the flow direction 106 after a second area 120 and before a first area 118.

[0143] As can be seen in the sectional side view of Fig. 1, a rising section 126 is ramp-shaped and can, for example, form an inlet ramp for a second section 120 with a second channel depth 124 or for a channel floor elevation. Furthermore, a falling section 128 is ramp-shaped and can form an outlet ramp for a second section 120 with a second channel depth 124 or for a channel floor elevation.

[0144] The gradient sections 126 of the flow channels 104 shorten depending on an increasing distance from a start of the respective flow channels 104 along the flow direction 106.

[0145] In this process, depending on an increasing distance from the beginning of the respective flow channels 104 along the flow direction 106, a slope, for example a positive slope, of the slope areas 126 increases.

[0146] Furthermore, the sinking areas 128 of the flow channels 104 shorten depending on the increasing distance from the beginning of the respective flow channels 104 along the flow direction 106.

[0147] In this process, depending on an increasing distance from the beginning of the respective flow channels 104 along the flow direction 106, a slope, for example negative slope or inclination, of the sinking areas 128 increases.

[0148] As indicated in Fig. 1 with circular segment-like arrows, the incline areas 126 or the positive incline can be assigned or associated with an angle of inclination, and the decline areas 128 or the negative incline can be assigned or associated with an angle of inclination.

[0149] Preferably, the angle of inclination lies in an angular range of 0.5° to 70°, for example from 1° to 45°, for example 3° to 30°, and the angle of inclination lies in an angular range of 0.5° to 70°, for example from 1° to 45°, for example 3° to 30° or 2° to 10°.

[0150] As can also be seen in Fig. 1, the slopes and / or inclination angles of the slope areas 126 of a flow channel 104 increase or are increasingly larger depending on an increasing distance from a beginning of this flow channel 104.

[0151] Such an increase in the gradients is preferably proportional to the aforementioned distance. All gradients of the gradient sections 126 of a flow channel 104 therefore differ from one another.

[0152] The negative slopes or inclination angles of the depression areas 128 are equal to or smaller than the slopes and / or inclination angles of the gradient areas 126.

[0153] For example, the negative slopes or inclination angles of the sinking areas 128 and the slopes and / or inclination angles of the rising areas 126 can be the same for a second area 120, which is provided as the first of several second areas 120 in a flow channel 104 in the direction of flow 106, and different for the second areas 120 following in the direction of flow 106.

[0154] In particular, the negative slopes or inclination angles of the sinking areas 128 of a flow channel 104 increase as a function of increasing distance from the beginning of this flow channel 104, so that in the present embodiment the negative slopes or inclination angles of all sinking areas 128 of a flow channel 104 are different from each other.

[0155] It is understood that the various sections 118, 120, 126, 128 of a flow channel 104 can also transition into one another in a curved and / or rounded manner, and that in this case the present description applies accordingly. For example, it may be provided that a first tangent 130, which lies at a geometric center of a first section 118 along the flow direction 106, and a second tangent 132, which lies at a geometric center of a slope section 126 adjacent to the first section 118 along the flow direction 106, are arranged at an angle to each other of 0.5° to 70°, for example, from 1° to 45°, or 3° to 30°.For example, it may be additionally or alternatively provided that a third tangent 134, which lies at a geometric center of a second region 120 along the flow direction 106, and a fourth tangent 136, which lies at a geometric center of a sinking region 128 adjacent to the second region 120 in question along the flow direction 106, are arranged at an angle of 0.5° to 45°, for example from 1° to 35°, for example 2° to 10°, to each other.

[0156] As can be seen from Fig. 2, expansion areas 138 and narrowing areas 140 of the flow channels 104 are formed by means of the webs 112, which limit the flow channels 104 to each other and in particular limit them laterally.

[0157] The flow channels 104 have alternating expansion areas 138 and narrowing areas 140 along the flow direction 106.

[0158] The expansion areas 138 and the narrowing areas 140 of adjacent flow channels 104 are arranged offset from each other along the flow direction 106.

[0159] For example, next to an expansion area 138 of a flow channel 104 runs at least one narrowing area 140 of an adjacent flow channel 104, or on both sides there is a narrowing area 140 of adjacent flow channels 104.

[0160] For example, next to a narrowing area 140 of a flow channel 104 runs at least one widening area 138 of an adjacent flow channel 104, or on both sides there is an widening area 138 of adjacent flow channels 104.

[0161] An expansion area 138 and a narrowing area 140 of adjacent flow channels 104 are thus arranged next to each other, for example with respect to one or the transverse direction of the bipolar plate 100.

[0162] The expansion areas 138 and the narrowing areas 140 of the flow channels 104 result in a varying channel width 142 of a respective flow channel 104, preferably a maximum channel width 144 in an expansion area 138 and a minimum channel width 146 in a narrowing area 140.

[0163] A channel width 142, 144, 146 is oriented transversely and preferably perpendicularly to a channel depth 116, 122, 124 and the flow direction 106.

[0164] An expansion area 138 preferably has a maximum channel width 144 and a narrowing area 140 has a minimum channel width 146. The minimum and maximum channel widths 146, 144 of a flow channel 104 are constant in the present embodiment.

[0165] A transition 148 arranged in the expansion area 138 from the minimum channel width 146 of the narrowing area 140 to the maximum channel width 144 of the expansion area 138 is in this case formed proportionally along the flow direction 106 and runs along the flow direction 106, for example, in a funnel shape and / or funnel-like manner.

[0166] Furthermore, a transition 150 arranged in the narrowing area 140 from the maximum channel width 144 of the widening area 138 to the minimum channel width 146 of the narrowing area 140 is formed proportionally along the flow direction 106 and runs along the flow direction 106, for example, in a funnel shape and / or funnel-like shape.

[0167] Each expansion area 138 of a flow channel 104 is provided with one of the first channel depths 122, preferably where the maximum channel width 144 of the expansion area 138 in question is provided.

[0168] Furthermore, each narrowing area 140 of a flow channel 104 is provided with one of the second channel depths 124, preferably where the minimum channel width 146 of the narrowing area 140 in question is provided.

[0169] This allows the cross-sectional area of ​​a given flow channel 104 to be further reduced, so that the prevailing flow velocity there is higher than the flow velocity prevailing in the region of the first channel depth 122 and the maximum channel width 144. The respective flow velocities are shown in Figs. 1 and 2 by means of arrows, with their different velocity values ​​being characterized by their length.

[0170] Furthermore, by arranging the expansion areas 138 and the narrowing areas 140 of adjacent flow channels 104 offset from each other along the flow direction 106, the first areas 118 and the second areas 120 of adjacent flow channels 104 are also offset from each other along the flow direction 106, and thus also the corresponding channel depths 122, 124. As already described, the flow channels 104 are laterally bounded, at least in sections, by the webs 112.

[0171] Preferred overflow sections 148 are provided in the expansion areas 138 and / or the narrowing areas 140, preferably in the area of ​​the maximum and minimum channel width 144, 146 and / or the first and second channel depth 122, 124.

[0172] These overflow sections 148 allow for increased overflow of the fluid medium between adjacent flow channels 104 (during operation). Such overflow is illustrated in Fig. 2 by means of the curved arrows.

[0173] Preferably, fluid medium flows from expansion areas 138 to narrowing areas 140 due to the pressure differences and / or flow velocity differences prevailing there.

[0174] Due to the expansion areas 138 and narrowing areas 140 as well as the first channel depths 122 and the second channel depths 124, a defined variation of a flow cross-section for the fluid medium can be provided in the flow direction 106 of each flow channel 104.

[0175] This allows the pressure and flow velocity of the fluid medium in the flow channels 104 and thus in the flow field 108 formed by the flow channels 104 to be specifically adjusted and set.

[0176] Advantageously, this can enable an improved and more uniform supply and / or distribution of the fluid medium to and / or at the gas diffusion layer 110 and thus ultimately to and / or at an electrochemically active area, e.g. a membrane electrode unit, a fuel cell device.

[0177] Furthermore, the design and / or arrangement of the expansion areas 138 and narrowing areas 140, as well as the first channel depths 122 and second channel depths 124, advantageously allows for targeted consideration of local conditions along a respective flow channel 104, i.e., the flow path of the fluid medium. This advantageously enables a more homogeneous distribution of the fluid medium and / or a uniform supply of the fluid medium to the gas diffusion layer 110 and thus ultimately to the electrochemically active area of ​​a fuel cell device.

[0178] The channel floor elevations or the second areas 120 in the flow channels 104, which, as described herein, are of varying intensity depending on their position in the flow channel 104 and thus in the flow field 108, advantageously enable an adjustment of the flow cross-section.

[0179] This allows static pressure differences between channel constrictions, here the narrowing areas 140, (high flow velocity) and wide channel areas, here the widening areas 138, (low flow velocity) to be locally adapted and / or influenced, preferably for the targeted increase of the overflow of the fluid medium between adjacent flow channels 104 via the overflow sections 148 (see curved arrows in Fig. 2).

[0180] Furthermore, the different slope angles in the inflow area, here the slope areas 126, the channel floor elevations or the second areas 120, can enable a flow impulse design of varying intensity in the direction of the gas diffusion layer 110 and thus ultimately in the direction of the electrochemically active area of ​​the fuel cell device.

[0181] Advantageously, this can be achieved while simultaneously minimizing any impact on flow pressure loss in the respective flow channel 104 or flow field 108, and can enable and / or support improved cross-flow of the fluid medium from flow channel 104 to flow channel 104 (see curved arrows in Fig. 2). List of reference symbols

[0182] Bipolar plate, bipolar plate position, flow channel, flow direction, flow field, gas diffusion position, rib

[0183] Channel floor Channel depth first area second area first channel depth second channel depth slope area sink area first tangent second tangent third tangent fourth tangent

[0184] Expansion area, narrowing area, varying channel width, maximum channel width, minimum channel width, overflow section

Claims

Patent claims 1. Bipolar plate (100) for a fuel cell device, comprising: at least one bipolar plate layer (102) on which a plurality of, in particular adjacent, flow channels (104) are provided, through which a fluid medium, in particular an operating gas of the fuel cell device, can be guided along a flow direction (106), wherein several, preferably all, flow channels (104) are connected along the Flow direction (106) varying channel depths (116) are provided, whereby - each flow channel (104) having a varying channel depth (116) has a plurality of first and second sections (118, 120), wherein the first sections (118) have a first channel depth (122) and the second sections (120) have a second channel depth (124), wherein the first and second sections (118, 120) are arranged alternately along the flow direction (106), and wherein the second channel depths (124) decrease in the second sections (120) along the flow direction (106).

2. Bipolar plate (100) according to claim 1 , characterized in that the first and second areas (118, 120) are provided alternately along the flow direction (106) at regular and / or irregular intervals.

3. Bipolar plate (100) according to one of the preceding claims, characterized in that at least one of the following is provided: with increasing distance from an inception of a flow channel (104), the second channel depths (124) in the second regions (120) decrease; and / or several, in particular all, of the second channel depths (124) of a flow channel (104) are different and / or the same; and / or the first channel depths (122) of a flow channel (104) are constant over a length of this flow channel (104); and / or with increasing distance from a start of a flow channel (104) the first channel depths (122) decrease and / or increase in the first regions (118); and / or several, in particular all, of the first channel depths (122) of a flow channel (104) are different and / or the same.

4. Bipolar plate (100) according to one of the preceding claims, characterized in that a decrease in the second channel depths (124) is proportional or disproportionate, preferably depending on an increasing distance from a start of a flow channel (104).

5. Bipolar plate (100) according to one of the preceding claims, characterized in that the channel depths (124) of adjacent second areas (120) differ from each other by between 1% and 60%, in particular between 3% and 50%, preferably between 5% and 35%.

6. Bipolar plate (100) according to one of the preceding claims, characterized in that a rising area (126) and / or a falling area (128) is formed between a first area (118) and a second area (120), wherein it is preferably provided that the rising areas (126) and / or the falling areas (128) of a relevant flow channel (104) shorten depending on an increasing distance from an initiation of this flow channel (104) along the flow direction (106) and / or a slope, in particular a positive slope and / or a negative slope, of the rising areas (126) and / or the falling areas (128) increases depending on an increasing distance from an initiation of a relevant flow channel (104).

7. Bipolar plate (100) according to claim 6, characterized in that the slopes of the slope regions (126) of a flow channel (104) are increasingly larger depending on an increasing distance from an initiation of this flow channel (104), wherein it is preferably provided that that the increase in the slopes is proportional or disproportionate; and / or that the respective slopes of several, in particular all, slope ranges (126) of a flow channel (104) are different from each other and / or are the same.

8. Bipolar plate (100) according to one of claims 6 or 7, characterized in that a tangent (130) which is located at a geometric center of a first region (118) along the flow direction (106), and a further tangent (132) which is located at a geometric center of a slope region (126) adjacent to the relevant first region (118) along the flow direction (106), are arranged at an angle of 0.5° to 70°, in particular from 1° to 45°, preferably 3° to 30°, to each other; and / or a tangent (134) which lies at a geometric center of a second region (120) along the flow direction (106), and a further tangent (136) which lies at a geometric center of a sinking region (128) adjacent to the second region (120) in question along the flow direction (106), are arranged at an angle of 0.5° to 45°, in particular from 1° to 35°, preferably 2° to 10°, to each other.

9. Bipolar plate (100) according to one of claims 6 to 8, characterized in that Distances between second sections (120) of the flow channel (104) decrease with increasing distance from a start of the flow channel (104); and / or Distances between first areas (118) of the flow channel (104) decrease with increasing distance from a beginning of the flow channel (104).

10. Bipolar plate (100) according to one of the preceding claims, characterized in that the flow channels (104) have alternating expansion areas (138) and narrowing areas (140) along the flow direction (106), wherein expansion areas (138) and / or narrowing areas (140) of adjacent flow channels (104) along the flow direction (106) are arranged offset from each other.

11. Bipolar plate (100) according to claim 10, characterized in that each expansion area (138) of a flow channel (104) is provided with one of the first channel depths (122); and / or each narrowing area (140) of a flow channel (104) is provided with one of the second channel depths (124).

12. Bipolar plate (100) according to one of claims 10 or 11, characterized in that the plurality of flow channels (104) are at least partially bounded by webs (112), in particular laterally, wherein the webs (112) in the widening regions (138) and / or the narrowing regions (140) of the flow channels (104) have one or more, in particular preferred, overflow sections (148) through which an, preferably enhanced, overflow of the fluid medium between adjacent flow channels (104) is made possible.

13. Bipolar plate (100) according to one of the preceding claims, characterized in that the plurality of flow channels (104) are at least partially bounded by webs (112), in particular laterally, wherein the webs (112) in regions (118, 120) of the first channel depths (122) and / or the second channel depths (124) of the flow channels (104) have one or more, in particular preferred, overflow sections (148) via which an, preferably enhanced, overflow of the fluid medium between adjacent flow channels (104) is made possible.

14. Bipolar plate arrangement for a fuel cell device, comprising: at least one bipolar plate (100) according to one of claims 1 to 13; and at least one gas diffusion layer (110) which is arranged on the bipolar plate (100) and in particular on a bipolar plate layer (102) of the bipolar plate (100).

15. Fuel cell device comprising: at least one bipolar plate (100) according to one of claims 1 to 13 and / or at least one bipolar plate arrangement according to claim 14.

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