DE102021102194A1 - Seal assembly for a fuel cell and method of manufacturing a seal assembly - Google Patents

Abstract

A sealing arrangement (1) of a fuel cell (10) comprises a strip arrangement (7) which is formed from two half-plates (4, 5) and a strip-shaped support component (6) which is located between the half-plates (4, 5) and has openings (12). . Each half-plate (4, 5) is designed as a supporting plate of a non-metallic sealing strip (8, 9) which is firmly connected to the half-plate (4, 5) and is arranged on the side of the respective half-plate (4, 5) facing away from the supporting component (6), the openings (12) of the support component (6) extending in the transverse direction of the sealing strip (8, 9) beyond the sealing strip (8, 9), whereby flow channels (13) running transversely to the sealing strip (8, 9) are formed.

Description

The invention relates to a sealing arrangement suitable for use in a fuel cell. Furthermore, the invention relates to a method for producing a sealing arrangement for a fuel cell.

the DE 10 2014 202 775 A1 discloses a bipolar plate for a fuel cell. Recesses in the bipolar plate form operating supply channels, which are to be sealed. A folded over section of the bipolar plate takes over after the DE 10 2014 202 775 A1 the function of a seal support bridge. The gasket support bridge bridges trenches formed by the bipolar plate and is provided to support a gasket placed across the trenches.

the DE 10 2014 009 329 B4 discloses a humidifier for a fuel cell. The humidification device is constructed as a stacked unit containing several water vapor-permeable membranes, two immediately adjacent membranes being connected in a flow-tight manner at a first edge region, whereas sealing strips lying one above the other are arranged at a second, angularly offset edge region. The membranes lie between these sealing strips, with flow openings being formed between the sealing strips lying one above the other. Due to the contouring of the sealing strips, there are flow openings only in the middle section of the sealing strips.

one in the EP 1 220 345 B1 described sealing arrangement of a fuel cell includes different seals, namely sealing sheets and seals inverted V-shape. Silicone rubber, nitrile rubber and fluorine rubber, among others, should be suitable for producing the seals.

Other variants of sealing arrangements in fuel cells are from the documents U.S. 9,653,747 B2 , U.S. 9,673,458 B2 , EP 1 693 915 B1 , U.S. 8,313,680 B2 and EP 3 545 570 B1 known.

The invention is based on the object of further developing seals and flow-guiding structures in fuel cells compared to the prior art, in particular from the point of view of a production-friendly, compact structure.

This object is achieved according to the invention by a sealing arrangement with the features of claim 1. The object is also achieved by a method for producing a sealing arrangement for a fuel cell according to claim 9. The configurations and advantages of the invention explained below in connection with the production method also apply accordingly for the device, i.e. the sealing arrangement of a fuel cell, and vice versa.

The sealing arrangement comprises an elongate arrangement referred to as a strip arrangement, which is formed from two half-sheets and a strip-shaped support component which is located between these half-sheets and has openings. In contrast to the supporting component, the half-sheets do not have any openings, at least in those areas in which the supporting component is sandwiched between the half-sheets. Like the half sheets, the support component is typically a sheet metal part, in particular made of sheet steel.

Each of the half-plates is designed as a supporting plate of a non-metallic sealing strip which is firmly connected to the respective half-plate and is arranged on the side of the half-plate facing away from the supporting component. The openings in the support component extend in the transverse direction of the sealing strip and thus also of the support component beyond the sealing strip, with the result that a plurality of flow channels running transversely to the sealing strip are formed for a liquid or gaseous medium.

Overall, this provides an arrangement suitable for installation between two flat elements of a fuel cell, which has both a sealing function, namely in relation to the two flat elements, and a flow-guiding function, with the medium conducted through the sealing arrangement flowing transversely to the longitudinal direction of the sealing arrangement.

The sealing arrangement is particularly suitable for use in a port area of a bipolar plate of a fuel cell, with hydrogen, air or pure oxygen and a typically liquid coolant flowing through the port area. The port area is sealed both internally and to the next cell of a fuel cell stack. The flow channels in the seal arrangement represent tunnels for one of the mentioned operating media in the seal. With the help of the flow channels, which are located in the support component, particularly favorable flow conditions can be achieved despite a space-saving design of the seal arrangement.

• - das Stützbauteil wird auf eines der Halbbleche derart aufgelegt, dass das Halbblech beidseitig über das Stützbauteil in dessen Längsrichtung hinausragt,
• - auf die aus dem ersten Halbblech und dem Stützbauteil gebildete Anordnung wird das zweite Halbblech aufgelegt, so dass zwischen den beiden Halbblechen zumindest in ihren das Stützbauteil überragenden Endabschnitten ein Luftspalt gebildet ist,
• - zumindest eines der Halbbleche wird in den Endabschnitten derart verformt, dass die Halbbleche in diesen Abschnitten unmittelbar aufeinander liegen, wogegen in dem zwischen den Endabschnitten befindlichen Hauptabschnitt der Halbbleche zwischen diesen Strömungskanäle in Form der Durchbrüche des Stützbauteils freigehalten werden,
• - auf den Halbblechen werden Dichtleisten angebracht, wobei Öffnungen der sich in Querrichtung der Dichtleisten erstreckenden Strömungskanäle freigehalten werden.

The sealing arrangement can be produced in the following steps using two profiled half-sheets and a strip-shaped support component with several openings:

• - the support component is placed on one of the half-plates in such a way that the half-plate projects beyond the support component in its longitudinal direction on both sides,
• - the second half-sheet is placed on the arrangement formed from the first half-sheet and the supporting component, so that an air gap is formed between the two half-sheets at least in their end sections projecting beyond the supporting component,
• - at least one of the half-plates is deformed in the end sections in such a way that the half-plates lie directly on top of each other in these sections, whereas in the main section located between the end sections the half-plates are kept free between these flow channels in the form of openings in the support component,
• - Sealing strips are attached to the half-plates, with openings in the flow channels extending in the transverse direction of the sealing strips being kept free.

The production of the sealing strips and simultaneous connection of the sealing strips with the half-sheets is possible in particular in the injection molding process. In principle, sealing strips can also be attached by vulcanization or gluing.

One advantage of the injection molding process is that there is more design freedom with regard to the cross-sectional shape of the seal, and precise positioning of the seal that is reliably reproducible even under the conditions of series production is possible.

In order to produce the sealing strips in the injection molding process, the strip arrangement formed from the two half-sheets, which can either have an identical shape or different geometries, and the support component is inserted into an injection molding tool. The strip arrangement can be an integral part of a bipolar plate of a fuel cell. When the injection molding tool is closed, the sealing edge of the tool must rest on the workpiece, i.e. the strip arrangement, with such high surface pressure at every point that the material from which the sealing strips are made is prevented from flowing out, even under the high injection pressure prevailing during injection molding . This requirement is met by the supporting component ensuring a constant distance between the two half-plates in the area of the sealing edges. Also in the area between the sealing edges, i.e. in the area in which material is applied to the half-plates by injection molding, the support component ensures a constant geometry of the half-plates, whereby in this case minimal deformations are less relevant than in the area of the sealing edges.

During the production of a fuel cell stack, a considerable force compressing the individual bipolar plates is exerted on the sealing strips of the sealing arrangements previously produced in the manner described. The metallic strip arrangement within the sealing arrangement also withstands this load, which is always present in the finished product, ie fuel cell stack. This also applies when using thin-walled half-sheets, which alone, i.e. without an additional support component, would not be able to form cavities suitable as flow channels that cross the sealing strip and both during an injection molding process and in later phases of production and use of the to get a fuel cell.

Overall, a generously dimensioned port tunnel is provided in a metallic bipolar plate with the aid of the support component having numerous openings, it being possible for the wall thickness of the support component to be greater than the sum of the wall thicknesses of both half-sheets. In particular, a large number of slits are provided in the support component as openings, with the slits running in the transverse direction of the support component each extending as far as an edge strip of the support component. It is also possible to use variants of the support component which only have a single edge strip, with the result that the support component has the basic shape of a comb. In this case, the open side of the ridge is, for example, on the side on which the medium flows out of the sealing arrangement. Non-slot-shaped openings in the support component are also possible.

If openings in the support component designed as transverse slots are closed off at both ends by a closed edge strip of the sheet metal strip, the length of each slot exceeds the port tunnel length of the flow channels to be measured in the same direction, insofar as these are delimited by the half sheets, for example by at least 5% , in particular by a minimum of 10% and a maximum of 30%. Those sections of the slots which protrude beyond the port tunnel allow the operating medium routed through the port tunnel to flow in and out.

Inside the port tunnel, its height does not necessarily match the strength of the support member. A greater height of the port tunnel can be achieved in particular by the edge strips of the supporting structure designed as sheet metal strips partly lie in a first plane and a main functional area of the metal strip having the slots is arranged in a plane parallel thereto.

According to various possible configurations, the total area of the openings in the support component corresponds to at least 30%, in particular 30% to 80%, of the main functional surface of the support component, the size of the main functional surface corresponding to the size of a rectangle circumscribing all the openings. The above-mentioned edge strips of the support component are therefore not part of its main functional area. The stated percentage of 30% to 80% refers to projection surfaces, regardless of any uneven design of the support component. In any case, the largest part of the main functional area lies within the port tunnel.

Both half-sheets can be offset in a strip-shaped area projecting beyond the sealing strips in such a way that a free space with a V-shaped cross section is formed between the strip-shaped areas of the half-sheets. This free space enables a particularly low-resistance flow of the operating medium conducted on a surface of the bipolar plate composed of the half-laminations. After the strip arrangement has been assembled and before the sealing strips are applied, the sheet metal halfs are typically not deformed in the area of the V-shaped free spaces. A significant deformation of at least one half-plate, as is provided within the scope of the manufacturing process, ensures a planar contact between the half-plates in the corresponding sections that protrude beyond the support component. This can be done by using half-sheets which—at least in the area of the sealing arrangement to be produced—first have an identical shape, the half-sheets only being brought into different shapes by the deformation that takes place after the assembly of the strip arrangement. At least in process stages prior to this deformation process, the half-sheets can be mirror-symmetrical to a central plane orthogonally intersecting the half-sheets, with only the area of the half-sheets attributable to the sealing arrangement being considered in this case as well.

• 1 Komponenten einer Dichtungsanordnung einer Brennstoffzelle in perspektivischer Ansicht,
• 2 ein Einzelteil, nämlich Stützbauteil, der Anordnung nach 1 in Draufsicht,
• 3 die Dichtungsanordnung in perspektivischer Ansicht,
• 4 das Stützbauteil in perspektivischer Ansicht,
• 5 die Dichtungsanordnung in einer Schnittdarstellung einschließlich umgebender Komponenten der Brennstoffzelle,
• 6 eine schematische Draufsicht auf Komponenten der Brennstoffzelle.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Show in it:

• 1 Components of a sealing arrangement of a fuel cell in a perspective view,
• 2 a single item, namely support member, according to the arrangement 1 in top view,
• 3 the sealing arrangement in a perspective view,
• 4 the support component in a perspective view,
• 5 the sealing arrangement in a sectional view including surrounding components of the fuel cell,
• 6 a schematic plan view of components of the fuel cell.

A sealing arrangement 1 is intended for use in a fuel cell 10, which is 6 is hinted at. With regard to the basic function of the fuel cell 10, reference is made to the prior art cited at the outset.

The sealing arrangement 1 is arranged between two flat components 2, 3 of the fuel cell 10, with a large number of components 2, 3 being arranged as components of the fuel cell 10 in a stacked form. The fuel cell 10 can be supplied with various operating media, namely hydrogen, coolant and air, in a manner known per se. A hydrogen port 17, a coolant port 18 and an air port 19 are provided for this purpose. In general, the port 17, 18, 19 is located on the port side PS of the sealing arrangement 1. The sealing arrangement 1 is located in a port tunnel area 20 and separates the port side PS from a patch panel side VS. The distributor panel, designated as a whole by 21, is connected by a respective port tunnel area 20, which in 5 is shown in more detail, connected to the associated port 17, 18, 19 in such a way that the respective operating medium can flow onto the distribution panel side VS, i.e. into the distribution panel 21, with static seals between the sealing arrangement 1 and the components 2, 3 being provided at the same time are. The sectional view 5 relates just like that 1 until 4 on each of the in 6 outlined port tunnel areas 20. In addition to the patch panel 21 is in 6 an active field 22 is indicated, in which electrical energy is generated in a manner known per se.

The sealing arrangement 1 comprises two half-plates 4, 5, which are arranged between the components 2, 3. A plane that intersects the sealing arrangement 1 in the middle and is oriented perpendicularly to the components 2, 3 is referred to as the center plane ME. in the in 5 The section shown shows a symmetry of the half-plates 4, 5 with respect to the center plane ME. This does not apply to areas of the half-plates 4, 5 that are outside of the section shown.

Between the half-plates 4, 5 there is a support member 6, which in the 2 and 4 is shown in isolation. In the 1 The arrangement shown, formed from the half-plates 4, 5 and the support component 6, is referred to as the strip arrangement 7. Sealing strips 8, 9, which are located on the half-plates 4, 5, complete the strip arrangement 7 to form the sealing arrangement 1.

The support member 6 has in plan view ( 2 ) has a rectangular basic shape, wherein numerous webs 11 can be seen in the transverse direction, between which openings 12, ie slots, are formed. The webs 11 and openings 12 are aligned in the direction of flow denoted by SR, in which the operating medium flows through the port tunnel area 20 . The width of the support component 6 in the corresponding direction is denoted as the total width Bges. Within the overall width Bges there is an inflow area, denoted by EB, for the operating medium, as well as an outflow area AB open to the distributor field side VS. Between the inflow area EB and the outflow area AB is the main functional area, designated HF, of the support component 6 integrated into the strip arrangement 7, in which flow channels 13 are formed by the openings 12 together with the half plates 4, 5. The main functional area HF has a width _BB .

The webs 11 extend from a first edge strip 14 of the support component 6 to a second edge strip 15, the edge strips 14, 15 being in the assembled state of the strip arrangement 7 in the inflow area EB or in the outflow area AB. The half-plates 4 , 5 protrude beyond the support component 6 in the longitudinal direction of the strip-shaped support component 6 denoted by LR. The corresponding areas of the half-plates 4 , 5 arranged in the longitudinal direction LR at the end of the sealing arrangement 1 are referred to as end areas or end sections 23 of the strip arrangement 7 . In contrast, that area in which the support component 6 is located between the half-plates 4, 5 is referred to as the middle section 24 of the strip arrangement 7 .

In the course of the manufacture of the strip arrangement 7, the half-sheets 4, 5 are first placed one on top of the other with the support component 6 sandwiched between them. In this state, there is initially an air gap between the half-sheets 4, 5 in the end sections 23. The half-sheets 4, 5 are then deformed in such a way that they lie flat on top of one another in the end sections 23. Alternatively, the deformation of the half-sheets 4, 5, which is necessary in order to avoid a distance between the half-sheets 4, 5 in the end sections 23, can already take place in a preceding step. In any case, the half-plates 4, 5 always remain at a distance from one another in the middle section 24 due to the support component 6, with the result that the flow channels 13 are kept open. This also applies to the production of the sealing strips 8, 9 by injection molding, in which high forces act between the half-plates 4, 5. Within the finished sealing arrangement 1, the half-plates 4, 5 function as a supporting plate for the non-metallic sealing strips 8, 9. In addition to the sealing strips 8, 9, i.e. in the inflow area EB and in the outflow area AB, there are cranked areas 16 of the half-plates 4, 5, which are particularly advantageous in terms of flow technology favorable conditions are produced in the form of V-shaped free spaces VR, which promote low-resistance flow through the port tunnel area 20.

Reference List

1

sealing arrangement

2

flat component

3

flat component

4

half sheet

5

half sheet

6

Support component, sheet metal strips

7

bar arrangement

8th

sealing strip

9

sealing strip

10

fuel cell

11

web

12

opening, slit

13

flow channel

14

sidebar

15

sidebar

16

crank area

17

hydrogen port

18

coolant port

19

air port

20

port tunnel area

21

patch panel

22

active field

23

end section

24

middle section

AWAY

outflow area

bb

Width of the main functional area

Bges

Overall width of the support member

EB

inflow area

HF

main functional area

LR

longitudinal direction

ME

midplane

hp

port side

SR

Flow direction, transverse direction

VR

V-shaped clearance

vs

patch panel side

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014202775 A1 [0002]
• DE 102014009329 B4 [0003]
• EP 1220345 B1 [0004]
• US 9653747 B2 [0005]
• US 9673458 B2 [0005]
• EP 1693915 B1 [0005]
• US8313680B2 [0005]
• EP 3545570 B1 [0005]

Claims (10)

Sealing arrangement (1) of a fuel cell (10), with a strip arrangement (7) formed from two half-sheets (4, 5) and a strip-shaped support component (6) having perforations (12) lying between the half-sheets (4, 5), each Half-plate (4, 5) is designed as a supporting plate of a non-metallic sealing strip (8, 9) which is firmly connected to the half-plate (4, 5) and is arranged on the side of the respective half-plate (4, 5) facing away from the supporting component (6), and the openings (12) of the support component (6) extending in the transverse direction of the sealing strip (8, 9) beyond the sealing strip (8, 9), whereby flow channels (13) running transversely to the sealing strip (8, 9) are formed. sealing arrangement claim 1 , characterized in that a metal strip is provided as the support component (6), which has a plurality of slots (12) as openings. sealing arrangement claim 2 , characterized in that the slots (12) are closed off at both ends by a closed edge strip (14, 15) of the metal strip (6), the length of each slot (12) being the port tunnel length of the flow channels to be measured in the same direction (13), insofar as these are limited by the half-plates (4, 5), by at least 5%. sealing arrangement claim 3 , characterized in that the edge strips (14, 15) of the metal strip (6) lie in a first plane and a slot (12) having the main functional area of the metal strip (6) is arranged in a plane parallel thereto. Sealing arrangement according to one of Claims 1 until 4 , characterized in that the total area of the openings (12) of the supporting component (6) corresponds to at least 30% of the area of the main functional area of the supporting component (6), the size of the main functional area corresponding to the size of a rectangle circumscribing all the openings (12). Sealing arrangement according to one of Claims 1 until 5 , characterized in that both half-plates (4, 5) are cranked in a strip-shaped area protruding beyond the sealing strips (8, 9) in such a way that a free space with a V-shaped cross section is formed between the strip-shaped areas of the half-plates (4, 5). Sealing arrangement according to one of Claims 1 until 6 , characterized in that the half-plates (4, 5) and the sealing strips (8, 9) project beyond the support component (6) in their longitudinal direction. Sealing arrangement according to one of Claims 1 until 7 , characterized in that this is formed mirror-symmetrical to a half-sheets (4, 5) orthogonally intersecting center plane (ME). Method for producing a sealing arrangement (1) for a fuel cell (10), with the following steps: - Provision of two profiled half-sheets (4, 5) and a strip-shaped support component (6) having openings (12), - placing the supporting component (6) on one of the half-sheets (5) in such a way that the half-sheet (5) projects beyond the supporting component (6) in its longitudinal direction on both sides, - Placing the second half-sheet (4) on the arrangement of the first half-sheet (5) and supporting component (6), so that an air gap is formed between the two half-sheets (4, 5) in their end sections (23) projecting beyond the supporting component (6). , - Deformation of at least one of the half-sheets (4, 5) in the end sections (23) in such a way that the half-sheets (4, 5) lie directly on top of one another in these sections (23), whereas in the central section (24 ) of the half-plates (4, 5) are kept free between these flow channels (13) in the form of openings (12) in the support component (6), - Attachment of sealing strips (8, 9) on the half-plates (4, 5), openings of the flow channels (13) arranged on the longitudinal sides of the support component (6) being kept free. procedure after claim 9 , characterized in that the half-sheets (4, 5) used initially have an identical shape and are brought into different shapes by the fourth method step.

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