Audi Ag

Oliver Keitsch

Armin Siebel

Fabian Lippl

Sebastian Voigt

Nico Riede

Martin Göbel

Daniela Könnicke

Raimund Theo Ströbel

A bipolar plate for a fuel cell comprises a first reactant flow field on its first plate side and a second reactant flow field on its second plate side, situated opposite the first plate side, wherein the flow fields comprise multiple flow ducts bounded by webs in an active region for one of the two reactants taking part in the fuel cell reaction, wherein each time the active region at the inlet side is fluidically connected via a distribution region running outside of the active region to an inlet-side media port for one of the two reactants, extending from the first plate side to the second plate side, and wherein each time the active region at the outlet side is fluidically connected via a collection region running outside the active region to an outlet-side media port extending from the first plate side to the second plate side. At least one of the flow fields is formed with webs at the inlet side in its active region, which have a bearing surface for a neighboring layer of the fuel cell which is larger than a bearing surface of the outlet-side webs, resulting from a duct division of at least some of the flow ducts which is present in the active region. A fuel cell stack having such a bipolar plate is also provided.

Bipolar plate having duct divisions present in the active region, and a fuel cell stack

A method for a frost start of a fuel cell device having a fuel cell stack, in which a plurality of fuel cells electrically switched in series is pressed by a compression force of a clamping device between two end plates, comprises determining the presence of frost start conditions, reducing the compression force by means of the clamping device, and operating the fuel cells in a frost start operation, in which a compression force acting on the fuel cells of the fuel cell stack and reduced as compared to that of a normal operation is maintained. A fuel cell device as well as a motor vehicle having a fuel cell device with a controller adapted to carry out such a method for a frost start of the fuel cell device are also provided.

Method for a frost start of a fuel cell device, fuel cell device and motor vehicle having a fuel cell device

A single cell for a fuel cell stack is provided, having a membrane electrode assembly arranged in an active region, being associated with at least one single plate, which is formed with a flow field to supply an operating medium to the active region of the membrane electrode assembly, which is fluidically connected to a media port present on the side away from the active region. Lateral with respect to the membrane electrode assembly there is a lamella at least partly covering the flow cross section of the media port, which is formed to be elastically bendable by the force of a reaction medium flowing axially through the media port in order to change the useful flow cross section of the media port. A fuel cell stack having a plurality of such single cells is also provided.

Single cell and fuel cell stack with elastic structures for equal distribution of operating media

A bipolar plate comprises a passive plate portion having a plurality of media ports and an active plate portion serving for the distribution of the reactants, wherein the passive plate portion and the active plate portion are coupled to each other by means of at least one spring element. A fuel cell stack comprising such a bipolar plate is also provided.

Bipolar plate and fuel cell stack

A fuel cell stack includes a plurality of fuel cells arranged in the direction of the stack and tensioned by means of tension elements, of which at least one has a cell voltage tap for electrical connection to a cell monitoring unit, wherein the at least one cell voltage tap is mechanically secured by at least one of the tension elements as regards the connection to the fuel cells. A fuel cell device and a motor vehicle with a fuel cell device are also provided.

Fuel cell stack, fuel cell device and motor vehicle with fuel cell device

A bipolar plate formed from two single plates joined together, formed with a reactant flow field on their plate surfaces facing away from each other, comprises multiple flow ducts for a reaction medium, bounded by walls of webs, wherein the webs and the flow ducts of one of the single plates run opposite the webs and the flow ducts of the other of the single plates in an active region, thus forming coolant ducts of a coolant flow field extending between the single plates, the reactant flow fields and the coolant flow field being each connected fluidically to a media port across a distribution region situated outside the active region, and there being a cross channeling of the two reaction media for a portion in the distribution region. For the channeling of the coolant in the distribution region free of cross currents, at least one of the single plates may be formed with a reduction in height of the webs on its plate surface facing toward the other of the single plates in an intersection region of the reaction media channels, so that two adjacent flow ducts are fluidically connected by the reduction.

A bipolar plate formed with a reactant flow field on each of its plate surfaces facing away from each other, comprises multiple flow ducts for a reaction medium, bounded by walls of webs, wherein the respective reactant flow field is connected fluidically to a media port across a distribution region situated outside an active region, wherein at least one duct of the distribution field is provided with a flow divider to divide up a flowing reaction medium before it is introduced into the active region. The duct comprising the flow divider has a duct elevation, comprising an ascent, which is present at a given distance upstream from the flow divider. A fuel cell stack having a plurality of such bipolar plates is also provided.

A bipolar plate has a first inlet port and a flow field comprising a plurality of ducts to connect the first inlet port to a first outlet port for a first reactant, and has a second inlet port and a flow field comprising a plurality of ducts to connect the second inlet port to a second outlet port for a second reactant, wherein at least one bypass duct is present at the margin of at least one of the flow fields. The bypass duct is associated with at least one flow connection branching off from the bypass duct into an adjacent marginal duct of the flow field.

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Heilbronn, Germany

Oliver Keitsch