WO2023083410A1 - Empilement de piles à combustible - Google Patents

Empilement de piles à combustible Download PDF

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Publication number
WO2023083410A1
WO2023083410A1 PCT/DE2022/100810 DE2022100810W WO2023083410A1 WO 2023083410 A1 WO2023083410 A1 WO 2023083410A1 DE 2022100810 W DE2022100810 W DE 2022100810W WO 2023083410 A1 WO2023083410 A1 WO 2023083410A1
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WO
WIPO (PCT)
Prior art keywords
fuel cell
cell stack
constant
force
spring
Prior art date
Application number
PCT/DE2022/100810
Other languages
German (de)
English (en)
Inventor
Barnaby Law
Ann-Kathrin Henss
Johannes Geisler
Wolfram Kaiser
Alexander FIEBIG
Sonja Schörshusen
Original Assignee
MTU Aero Engines AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by MTU Aero Engines AG filed Critical MTU Aero Engines AG
Publication of WO2023083410A1 publication Critical patent/WO2023083410A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/2465—Details of groupings of fuel cells
    • H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
    • H01M8/248—Means for compression of the fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2250/00—Fuel cells for particular applications; Specific features of fuel cell system
    • H01M2250/20—Fuel cells in motive systems, e.g. vehicle, ship, plane

Definitions

  • the present invention relates to a fuel cell stack, in particular for a propulsion unit of an aircraft.
  • a fuel cell stack also referred to as a stack
  • a channel plate with a channel structure for gas distribution or cooling for example a so-called bipolar plate
  • the power or voltage of the stack can be adapted to the application via the number of fuel cells connected in series in this way.
  • the present invention is based on the technical problem of specifying an advantageous fuel cell stack.
  • a spring element is arranged between a cover element, which is arranged following the fuel cells in the stacking direction and holds them together with a pressing force, and the fuel cells.
  • the force does not increase linearly with the path, i.e. the deflection or deformation, but remains in the working range essentially the same.
  • the pressing force transmitted to the fuel cells is at least somewhat decoupled from any bending or other inhomogeneity of the cover element, for example also from geometric inhomogeneities that can arise as a result of manufacturing fluctuations.
  • the constant-force spring element which can be part of a constant-force spring plate, for example, can thus result in an equalization of the force or pressure distribution that is applied to the stack over a large area.
  • Bending or warping of the cover element can generally also be prevented by a correspondingly thickened or locally thickened design, but this can significantly increase the weight, which can generally be disadvantageous with regard to mobility applications and in particular in the field of flight. Irrespective of this, inhomogeneities from manufacturing tolerances can still arise even with a stiffer cover element. On the other hand, especially in such applications, fuel cells with a larger area can be of interest due to the high power requirement, which can exacerbate the warping problem or make the occurrence of local inhomogeneities more likely.
  • the fuel cells are arranged one after the other; perpendicular to this, they each have, for example, their two-dimensional extension (and their surface is taken accordingly). “Consecutive” does not necessarily mean contiguous.
  • a channel plate in particular a bipolar plate, is preferably arranged between two fuel cells (see also the comments at the beginning).
  • the cover element is also preferably designed in the form of a plate, i.e. it has it a smaller extent in the stacking direction than in the surface directions perpendicular thereto.
  • the constant-force spring element can be realized in detail in different ways, for example, reference is made to Minhaz Ur Rahman et al., "Design of Constant Force Compliant Mechanisms", IJERT, Vol. 3 Issue ?, July-14.
  • the constant-force spring element can, for example, have a spring strut which, viewed in a section parallel to the stacking direction, extends between the pressing element and the fuel cells with a section that is proximal to the cover element and a section that is proximal to the fuel cells, with the two sections being offset from one another perpendicular to the stacking direction and through are connected to one another by a connecting section which extends at an angle, preferably essentially perpendicularly, to the stacking direction.
  • the proximal sections can extend essentially parallel to the stacking direction and, viewed in the section, merge into the connecting section at a respective kink point or in a continuously differentiable manner.
  • the spring element preferably has a first and a second spring leg, each correspondingly shaped, with the spring legs extending away from one another, ie diverging in the connecting sections and being at least approximately symmetrical with respect to an intermediate plane.
  • "a" and "an” in the context of the present disclosure are to be understood as indefinite articles and thus always as “at least one” or “at least one” unless expressly stated otherwise, so the spring element can also have more than two legs, for example have.
  • a respective spring strut can be perpendicular to said sectional plane, ie perpendicular to the stacking direction, in particular translationally symmetrical or prismatic.
  • a variable thickness is also possible, for example, so that the constant-force spring element can be adapted, for example, to a mechanical load profile that varies over the surface.
  • the adjustment or optimization can, for example, be such that the elasticity limit of the spring element material is not exceeded at any point on the spring element.
  • the constant-force spring element is prestressed to a working range over which the spring force only changes by a maximum of 10% in relation to a mean value, ie a maximum of +/-10%.
  • the working range can, for example, be at least 30%, 40%, 50% or 60% of S max .
  • the spring force can, for example, be essentially constant until s max is reached, for example away from at least 0.7 s max , 0.6 s max , 0.5 s max or 0.4 s max .
  • the behavior can also correspond to that of an ideal spring, i.e. the force increases linearly with the path (but non-linear behavior is also possible).
  • a contact area with which a spring strut of the constant-force spring element rests facing the fuel cells is arranged flush with a web of a channel plate.
  • “Aligned” refers to the stacking direction, in which the web and the arrangement area are arranged at least in an overlapping or congruent manner. The force is thus introduced into the stack at the point where force can actually be absorbed or transmitted in the stack. This allows, for example, an at least regionally uniform introduction or transmission of force, preferably into the webs of the channel plates, even if the contact area does not cover the entire stack over an area.
  • a web of the channel plate is part of or forms, ie delimits at least in some areas, a channel structure via which hydrogen or oxygen, for example, can be supplied to the respective fuel cell or water can also be removed therefrom. Furthermore, such a channel structure can also be used for cooling purposes, ie a cooling fluid can flow through it.
  • the channel structure also referred to as flow field Q-, can be formed by a plurality of webs that rise, for example, in the stacking direction and run parallel to one another at least in sections (these delimit the channel structure perpendicular to the stacking direction).
  • the channel plate can be a monopolar plate arranged between these and the spring element at the end of the stacked fuel cells, or else a bipolar plate which is arranged in the stack between two fuel cells.
  • the contact area of the spring strut is arranged flush with both the web of a monopolar plate and the web of a bipolar plate, which can result in good force introduction and transmission.
  • the spring strut has a linear contact area, with a straight contact area being preferred. This can, for example, simplify the alignment relative to the web(s).
  • An arrangement can be preferred such that the linear contact area of the spring strut lies parallel to a web of a channel plate, for example the web of a monopolar plate and/or the web of a bipolar plate. It can be arranged flush with a web of the respective channel plate (see above), but it can also lie between two webs of a channel plate (in the middle or offset from the middle).
  • the cover element and the spring element can generally be in several pieces, that is to say they can be put together in the stack as previously separately produced parts. According to a preferred embodiment, they are integral with one another, ie cannot be separated from one another without being destroyed.
  • the one-piece can result, for example, from a joining connection or from a transition or press fit, but the spring and cover element can also be produced integrally, for example in a casting or pressure or extrusion process.
  • a cascading element is arranged between the spring element, for example a spring plate with the spring element, and the fuel cell, which spreads out the force transmitted by the spring element.
  • the cascading element can be divided into at least two legs at a branching point in a cascading direction, which is opposite to the stacking direction, wherein it there are preferably several branching points connected in parallel and/or several branching points connected in series (in each case based on the cascading direction).
  • the former means that there are several branching points in a respective cascading stage, e.g n > 2).
  • the series connection means that there are several branching points along the cascading direction, ie a web running out of a first cascading stage/level is then branched again.
  • constant-force spring elements can also be arranged one behind the other, ie connected in series or series, between the fuel cells and the cover element.
  • Such a series connection can be combined with a cascading element or, in particular, represent an alternative to it.
  • the pressing force with which the cover element holds the stacked fuel cells together can be applied to the cover element in any form, for example by pressure or spreading from a side facing away from the fuel cells.
  • the cover element is, at least indirectly, secured against the spring element or the fuel cells with one or in particular a plurality of tension elements, for example tension rods or tension straps. strains. It is preferably pulled in the direction of a further cover element which is arranged at the opposite end of the stacked fuel cells.
  • the tie rod or the tie straps preferably extend outside of the stacked fuel cells, that is to say laterally offset (and in this case, for example, parallel to the stacking direction).
  • spring elements according to the invention are made of a superelastic metal alloy, in particular also a shape memory alloy, wherein the aforementioned alloy has a transition temperature below 70°C, preferably below 20°C, particularly preferably below -30°C and moreover a superelasticity of at least 0.5%, preferably more than 3%, particularly preferably more than 10%.
  • the present invention also relates to a spring element (19, 20) for a fuel cell stack, which is made from a superelastic metal alloy.
  • the invention also relates to a propulsion unit for an airplane or an aircraft, which has a fuel cell stack disclosed in the present case. Furthermore, it relates to the use of such a drive unit or the fuel cell stack in an airplane or an aircraft.
  • FIG. 1 shows a fuel cell stack in a schematic section with a constant-force spring element
  • FIG. 2 shows a cover element with the constant-force spring element in a detailed illustration
  • FIG. 3 shows a force-displacement diagram of the constant-force spring element
  • Figure 4a-c different construction and arrangement options with one or more constant force spring elements
  • FIG. 5a, b cascading elements for spreading the force transmitted with the constant-force spring element
  • FIG. 6 shows an alternative constant-force spring element design to FIG.
  • the 1 shows a fuel cell stack 1 with a plurality of fuel cells 2 in a schematic section.
  • the fuel cells 2 are arranged one after the other in a stacking direction 5 , a channel plate 3 , namely a bipolar plate 4 , being arranged between each of two fuel cells 2 .
  • the stacked fuel cells 2 are also bordered at the end by a channel plate 3, namely a monopolar plate 6.
  • the channel plates 3 each have a plurality of webs 3.1, which together form a respective channel structure 3.2. Gas, in the present example hydrogen and oxygen, flows through these channel structures 3.2 during operation for the combustion process.
  • the monopolar plate 6 is followed by a current collector plate 7, and this is followed by a cover element 10, which is designed here as a cover plate 11 and mechanically holds the stacked fuel cells 2 and channel plates 3 together.
  • the cover element 10 is penetrated by tension elements 12 and thus braced under tension.
  • the stack is constructed analogously, ie a monopolar plate, a current collector plate and a cover element braced with the tension elements 12 are arranged.
  • the strain can result in warping of the cover element 10, particularly in the case of geometries that are larger in the surface direction 13 or designs with reduced thickness. men.
  • a spring element 19 shown schematically here, is arranged between the cover element 10 and the stacked fuel cells 2, namely a constant-force spring element 20.
  • FIG. 2 shows the cover element 10 and the constant-force spring element 20 in a detailed view, in section.
  • the constant-force spring element 20 has a first and a second spring strut 21, 22, with the spring struts 21, 22 each being in a section 21.1, 22.1 proximal to the cover element 10, a connecting section 21.2, 22.2 and a section 21.3, 22.3 proximal to the fuel cells structure
  • these sections 21.1-21.3, 22.1-22.3 each run at an angle to one another, the respective connecting section 21.2, 22.2 is essentially perpendicular to the stacking direction 5.
  • the first and second spring struts are present at least partially symmetrical to a vertical mirror plane, not shown arranged.
  • the spring struts 21, 22 can, as shown here, be designed to be self-supporting at one end, but a base plate can also be formed there.
  • FIG. 3 illustrates the behavior of the constant-force spring element 20 in a force-displacement diagram 30.
  • the displacement s is plotted on the x-axis
  • the force F is plotted on the y-axis.
  • Spring element 20 in the present example still like an ideal spring, so the force increases linearly with the path.
  • the force F remains essentially constant in the event of further deformation. Beyond the working range, the element behaves in principle analogously to the preload range, with further increasing force. In relation to the fuel cell stack 1, this means in the working area of the spring element that the introduction of force into the stack remains unchanged, even if the cover element 10 bends, for example, or there are deviations as a result of manufacturing tolerances.
  • Figures 4a-c show different arrangement options, also based on the position of the webs 3.1 of the channel plate 3.
  • the spring legs 21, 22 of the constant Force-spring elements 20 each have a contact area 41, 42, in this case on an intermediate plate 45, via which the force is transmitted to channel plate 3.
  • the contact areas 41, 42 are each linear, namely extend in the present case perpendicularly to the plane of the drawing and thus parallel to the webs 3.1 of the channel plate 3.
  • Figure 4b By using several constant-force spring elements 20 connected in parallel (Figure 4b), the introduction of force can be distributed over the surface direction 13 become.
  • Positioning of the contact areas 41, 42 in alignment with the webs 3.1 in the stacking direction 5 can also be advantageous, see FIG. 4c.
  • the introduction of force from the constant-force spring element 20 thus takes place at precisely those points at which transmission within the stack is also possible.
  • cascading elements 50 which can be arranged between the latter and the stack, in particular the monopolar plate 6, to spread the force transmitted by the constant-force spring element 20, see also FIG.
  • the cascading element 50 is shown in dashed lines as an optional feature; it can, for example, be used as an alternative to the parallel connection according to FIG. 4b or in combination with it, for example with a particularly large plate.
  • a cascading element 50 with two legs per associated individual spring element can be particularly preferred.
  • the cascading elements 50 each have a plurality of branching points 51-53, both in relation to a cascading direction 55 and within a respective cascading level (applies to the branching points 52 and 53).
  • a respective branch 60 divides into at least two branches 60.1, 60.2, which for the sake of clarity is only referenced with reference symbols for exactly one branching point 52.
  • the branching point is designed in accordance with a joint or a joint bearing, optionally also without moving parts.
  • the two cascading elements 50 then differ in that in the variant according to FIG. 5b there is complete decoupling away from the branching points 51-53, whereas there are still cross-connections 65 in FIG. 5a.
  • Both Cascading elements 50 can be produced, at least in certain areas, for example as extrusion profiles.
  • FIG. 6 shows a constant-force spring element 20 as an alternative to FIG. In contrast to FIG. 2, however, these do not merge smoothly, that is to say continuously differentiable, but rather merge into one another at break points 70 .
  • Such a constant force spring element 20 is taught by Lan et al. described in the article "A Compliant Constant-Force Mechanism for Adaptive Robot End-Effect Operations" (IEEE International Conference on Robotics and Automation,

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

La présente invention concerne un empilement de piles à combustible (1), comprenant : des piles à combustible (2) disposées successivement dans une direction d'empilement (5) ; un élément de recouvrement (10) qui suit les piles à combustible (2) dans la direction d'empilement (5) et les maintient ensemble ; et un élément ressort (19) qui est disposé entre les piles à combustible (2) et l'élément de recouvrement (10) dans la direction d'empilement (5), l'élément de ressort (19) étant un élément de ressort à force constante (20).
PCT/DE2022/100810 2021-11-11 2022-11-03 Empilement de piles à combustible WO2023083410A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102021129380.4 2021-11-11
DE102021129380.4A DE102021129380A1 (de) 2021-11-11 2021-11-11 Brennstoffzellenstapel

Publications (1)

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WO2023083410A1 true WO2023083410A1 (fr) 2023-05-19

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030104263A1 (en) * 1999-10-07 2003-06-05 Molter Trent M. Apparatus and method for maintaining compression of the active area in an electrochemical cell
US20050164077A1 (en) * 2004-01-28 2005-07-28 Bruno Bacon Pressure producing apparatus for an electrochemical generator
DE102017215748A1 (de) * 2017-09-07 2019-03-07 Audi Ag Kompressionsvorrichtung für einen Brennstoffzellenstapel
EP3719899A1 (fr) * 2017-11-29 2020-10-07 Nissan Motor Co., Ltd. Assemblage de piles à combustible
DE102019211595A1 (de) * 2019-08-01 2021-02-04 Audi Ag Brennstoffzellenstapel, Verfahren zur Einstellung der Verpresskraft eines Brennstoffzellenstapels sowie Kraftfahrzeug

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4821162B2 (ja) 2005-04-13 2011-11-24 トヨタ自動車株式会社 燃料電池スタックの製造方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030104263A1 (en) * 1999-10-07 2003-06-05 Molter Trent M. Apparatus and method for maintaining compression of the active area in an electrochemical cell
US20050164077A1 (en) * 2004-01-28 2005-07-28 Bruno Bacon Pressure producing apparatus for an electrochemical generator
DE102017215748A1 (de) * 2017-09-07 2019-03-07 Audi Ag Kompressionsvorrichtung für einen Brennstoffzellenstapel
EP3719899A1 (fr) * 2017-11-29 2020-10-07 Nissan Motor Co., Ltd. Assemblage de piles à combustible
DE102019211595A1 (de) * 2019-08-01 2021-02-04 Audi Ag Brennstoffzellenstapel, Verfahren zur Einstellung der Verpresskraft eines Brennstoffzellenstapels sowie Kraftfahrzeug

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
LAN ET AL.: "A Compliant Constant-Force Mechanism for Adaptive Robot End-Effector Operations", IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, 2010
UR RAHMAN ET AL.: "Design of Constant Force Compliant Mechanisms", IJERT, vol. 3

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DE102021129380A1 (de) 2023-05-11

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