DE10135336C1 - Fuel cell unit for fuel cell block has 2 housing parts sealed together via coupling surface parallel to stacking direction of fuel cell units within fuel cell block - Google Patents

Abstract

The fuel cell unit has a housing with 2 housing parts which are sealed together via a coupling surface parallel to the stacking direction of fuel cell units within a fuel cell block, provided by a flange extending perpendicular to the stacking direction. An Independent claim for a fuel cell block with a number of fuel cell units is also included.

Description

The present invention relates to a fuel cell unit for a fuel cell block assembly, which one Includes a plurality of fuel cell units, the longitudinal follow a stacking direction, the fuel cell unit a housing with a first housing part and a second housing part, which is essentially gas-tight are connected together, and wherein the first Ge housing part has a first connecting surface on which the first housing part fixed to the second housing part is.

From German patent application 100 44 703 of the same application Such a fuel cell unit is known in which is a first housing designed as a contact plate part has a connecting surface which is perpendicular to the Stack direction is aligned, with the contact plate this connection surface by welding or soldering a second housing designed as a fluid guide frame part is fixed.

Due to manufacturing tolerances in the manufacture of the Contact plate and the fluid guide frame or due to Assembly tolerances when assembling the casing of the burner unit cell unit, however, it may happen that the conn contact surface of the contact plate not everywhere on the Fluid guide frame rests so that the ver to each other binding areas of the contact plate and the fluid guide frame during welding or soldering  must be pressed against each other to get sufficient gas tightness of the connection between these two housing parts to reach.

The present invention is therefore based on the object a fuel cell unit of the type mentioned create, whose housing is easy and quick to assemble.

This task is carried out with a fuel cell unit Features of the preamble of claim 1 according to the invention solved by that the first interface substantially parallel to the stacking direction of the fuel cell block ver is aligned.

The fact that in the fuel cells according to the invention the first connection surface parallel to the stack direction device, manufacturing tolerances at the Manufacture of the two housing parts thereby compensated for who that the two housing parts to be connected to each other when assembling the housing along the stacking direction so ge be moved towards each other, that the gas-tight connection between the first connecting surface of the first housing part and the second housing part can be manufactured.

In a preferred embodiment of the invention Fuel cell unit is provided that the first connection arranged on a first connecting flange is, wherein the first connecting flange along a bend never adjoins an area of the first housing part that is in the aligned substantially perpendicular to the stacking direction is, and wherein the first connecting flange of this  Area of the first housing part from substantially parallel extends to the stacking direction.

In particular, it can be provided that the first connection flange out essentially perpendicular to the stacking direction directed area of the first housing part in a ring shape gives.

It is also preferably provided that the second housing partly has a second connecting flange, which is longitudinal a bending line to an area of the second housing part adjacent, which is substantially perpendicular to the stacking direction and which is different from this area of the second housing part from substantially parallel to the Sta direction extends.

In particular, it can be provided that the second connection tion flange of the second housing part a sliding seat bil det, in which the first connecting flange of the first housing partly slidably received along the stacking direction. In this way, possibly occurring manufacturing and Assembly tolerances can be compensated particularly easily.

It is advantageously provided that the second connection has a free edge on which the second Connecting flange is connected to the first housing part, so this has the advantage that the connection point between rule the first housing part and the second housing part is particularly easy to access from outside the housing.  

For the same reason, it is advantageous if the first ver binding flange has a free edge on which the first Connecting flange is connected to the second housing part.

The first housing part and the second housing part are in front preferably by welding, especially by laser welding and / or by soldering, in particular by brazing ten, essentially gas-tight.

Claim 8 is for a fuel cell block composite tet, which is a plurality of fuel according to the invention comprises cell units which are aligned along the stacking direction other follow.

To manufacture the housing of the fuel cell unit To simplify further, the housing parts are the fuel cell unit preferably designed as sheet metal parts, by one or more forming processes, in particular by stamping and / or deep drawing, from essentially flat Sheet metal blanks are produced.

The construction of a fuel cell unit according to the invention is particularly suitable for so-called high-temperature firing fabric cell units that have an operating temperature of up to Have 1000 ° C and directly with an external reformer hydrocarbon-containing fuel gas such as methane or natural gas or, alternatively, using a external reformer, with a hydrocarbon Fuel gas, such as methane, natural gas, diesel or Gasoline fuel can be operated.  

For use in such a high temperature fuel cell leneinheit the housing parts of the housing of the Brenn fabric cell unit made of a sheet material, the chemically at temperatures of up to 1000 ° C resistant to the components of the fuel gas, which too guided combustion air and one supplied if necessary th coolant (for example cooling air).

High-temperature resistant are particularly suitable for this Stainless steel sheets or with an inorganic or ceramic Material coated steel sheets.

The thickness of the sheet material used is preferred wise at the most about 3 mm, in particular at the most about 1 mm.

Other features and advantages of the invention are the subject the following description and graphic representation of embodiments. The drawings show:

Figure 1 is a schematic perspective view of a fuel cell device with feed lines and discharge lines for the Oxidationsmit tel and the fuel gas.

FIG. 2 shows a schematic vertical section through a composite fuel cell arranged in the housing of the fuel cell device from FIG. 1; FIG.

Fig. 3 is a plan view from above of the end plates of the fuel cell stack assembly of Fig. 2;

Figure 4 is a schematic longitudinal section through a Ka anode-anode electrolyte unit with adjoining contact plates.

Fig. 5 is a schematic plan view of a contact plate of a fuel cell unit;

Fig. 6 is a schematic plan view of a fluid guide frame of a fuel cell unit;

Figure 7 shows the right part of a schematic cross section through four consecutive fuel cell units in the stacking direction of the fuel cell block assembly.

Figure 8 shows the right part of a schematic longitudinal section through four consecutive fuel cell units in the region of a gas channel along the stacking direction of the fuel cell block assembly.

Figure 9 is the right part of a schematic longitudinal section through four along the stacking direction of the fuel cell stack assembly successive fuel cell units in the region between two gas channels.

Fig. 10 is a schematic perspective view of a surrounding a gas duct from the annular support member of a fuel cell unit;

FIG. 11 shows an enlarged representation of area I from FIG. 7;

FIG. 12 is a schematic perspective Explosionsdar two position in the stacking direction aufeinan derfolgender fuel cell units;

FIG. 13 is a plan view of the housing of a fuel cell unit in the region of Gasdurchgangsöff voltage in a second embodiment of the internal material-cell unit, which support members a plurality a lumps formed with the housing walls From comprises;

FIG. 14 shows a schematic section through the housing of the fuel cell unit from FIG. 13 along the line 14-14 in FIG. 13; and

Fig. 15 is a schematic section through the housing of the fuel cell unit of Fig. 13 along the Li never 15-15 in Fig. 13.

The same or functionally equivalent elements are in all fi guren with the same reference numerals.

A shown in FIGS. 1 to 12, as a whole by reference 100 fuel cell device comprising a cuboid in Wesent union housing 102 (see Fig. 1) into which an oxidizing agent supply line empties 104, on the the inner space of the housing 102, an oxidizing agent , for example air or pure oxygen, is supplied by a (not shown) supply fan under an excess pressure of, for example, approximately 50 mbar.

Furthermore, an oxidant discharge line 105 opens into the housing 102 , through which excess oxidant can be removed from the interior of the housing 102 .

In the interior of the housing 102 shown as a whole in FIGS. 2 and 3 fuel cell block composite 106 is arranged, which has a lower end plate 108, a middle upper end plate 110, two side upper end plates 111 and a plurality between the lower end plate 108 and the obe Ren end plates 110 , 111 arranged, along a stack direction 112 consecutive fuel cell units 114 comprises.

As best seen from Fig. 12 showing a via-perspective exploded view of two along the stacking direction 112 of successive fuel cell units 114, each of the fuel cell units 114 comprises a substantially plate-shaped cathode-anode-electrolyte unit 116 (hereinafter referred to briefly as KAE -Unit designated), which is held between a contact plate 118 and a fluid guide frame 120 .

The KAE unit 116 comprises, as shown purely schematically in FIG. 4, a gas-permeable, electrically conductive substrate 121 , which can be designed, for example, as a metal wire mesh, metal wire fleece, metal wire mesh, metal wire knit or as a porous body consisting of sintered or pressed metal particles can, whereby a fuel gas can pass through a substrate 121 from a fuel gas space 124 adjacent to the substrate 121 .

Furthermore, the KAE unit 116 comprises a plate-shaped anode 122, which is arranged on the substrate 121 and is made of an electrically conductive ceramic material, for example Ni-ZrO ₂ cermet (ceramic-metal mixture), which is porous in order to remove the fuel gas from the fuel gas chamber 124 Allow passage through the anode 122 to the electrolyte 126 adjacent to the anode 122 .

A hydrocarbon content, for example, can be used as the fuel gas gas mixture or pure hydrogen can be used.

The electrolyte 126 is preferably designed as a solid electrolyte and is formed, for example, from yttrium-stabilized zirconium dioxide.

On the side of the electrolyte 126 opposite the anode 122 , a plate-shaped cathode 128 , which is formed from an electrically conductive ceramic material, for example from LaMnO ₃ , and has a porosity around an oxidizing agent, for example air or pure oxygen, borders on the same to allow an oxidant space 130 adjacent to the cathode 128 to pass through to the electrolyte 126 .

The electrolyte 126 is essentially gas-tight, so that no oxidizing agent can pass from the oxidizing agent space 130 through the electrolyte 126 into the fuel gas space 124 and no fuel gas from the fuel gas space 124 through the electrolyte 126 into the oxidizing agent space 130 .

In operation of the fuel cell device, the KAE unit 116 of each fuel cell unit 114 has a temperature of, for example, approximately 850 ° C., at which the electrolyte 126 is conductive for oxygen ions. The oxidizing agent from the oxidizing agent space 130 receives electrons at the anode 122 and emits divalent oxygen ions from the electrolyte 126 , which migrate through the electrolyte 126 to the anode 122 . At the anode 122 , the fuel gas from the fuel gas chamber 124 is oxidized by the oxygen ions from the electrolyte 126 and thereby releases electrons to the anode 122 .

The contact plates 118 serve to remove the electrons released during the reaction at the anode 122 from the anode 122 via the substrate 121 or to feed the electrons required for the reaction at the cathode 128 to the cathode 128 .

For this purpose, each of the contact plates 118 consists of an electrically electrically conductive metal sheet which (as can best be seen from FIG. 5) is provided with a plurality of contact elements 132 , which for example have the shape extending in the longitudinal direction 133 of the contact plate 118 have ribs, which follow 118 to each other in the transverse direction 131 of the contact plate, wherein the following one another in the transverse direction 131. Contact elements 132 are immediately adjacent to each other and from the central plane 139 of the contact plate 118 projecting from alternately clock-plate to different sides of the Kon 118th The protruding from the contact plate 118 up and thus to the anode 122 of the same fuel cell unit 114 associated KAE unit 116 ends anode-side contact elements are with the reference symbol 132 a, which from the contact plate 118 down and thus to the cathode 128 one adjacent fuel cell unit 114 associated KAE unit 116 projecting catho-side contact elements are denoted by reference numeral 132 b.

Each of the contact elements 132 has a central strip-shaped contact area 137, where it communicates with a angren collapsing KAE unit 116 in electrically conductive contact (see, in particular Fig. 4 and Fig. 7).

The contact areas 137 of the anode-side contact members 132 a of a contact plate 118 are provided with the substrate 121 and thus 114 associated with the anode 122 of the same fuel cell unit KAE unit 116 clocking in electrical Flächenkon so that electrons may reach the contact plate 118 from the respective anode 122 ,

The cathode-side contact elements 132 b of the contact plates 118 are each in electrically conductive surface contact with the cathode 128 of the KAE unit 116 belonging to an adjacent fuel cell unit 114 , so that electrons can reach the cathode 128 from the contact plate 118 . In this way, the contact plates 118 enable the charge balance between the anodes 122 and the cathodes 128 along the stacking direction 112 of successive KAE units 116 .

The at the ends of the fuel cell block assembly 106 arranged contact plates 118 are connected (in a manner not shown in the drawing) to an external circuit in order to tap off the electrical charges that are formed on these marginal contact plates 118 .

The contact field 134 formed from the contact elements 132 of each contact plate 118 has the structure of a corrugated sheet in the transverse direction 131 of the contact plate 118 .

As best seen in the plan view of Fig. 5, is the central, substantially rectangular contact array 134 approximate range embedded provided with the contact elements 132 of each contact plate 118 in a flat, substantially rectangular Gasfüh 136 of the contact plate 118.

The gas guide area 136 has on both sides of the contact field 134 each a side area 140 a and 140 b.

Several, for example two, substantially circular fuel gas through openings 142 are formed in the side region 140 a.

Each of the fuel gas passage openings 142 is surrounded by a ring-shaped edge region 144 , each of the regions 142 being offset relative to the gas guide region 136 along the stacking direction 112 downward and with the gas guide region 136 via a slope 146 , which on an inner bending line 148 to the each border area 144 and along an outer bending line 150 adjacent to the gas guide area 136 , is connected.

The fuel gas through openings 142 serve for the passage of fuel gas to be supplied from the fuel cell units 114 through the respective contact plate 118 .

The side region 140 a opposite side region 140 b of each contact plate 118 is provided with a plurality, for example with three, substantially circular exhaust passage openings 152 .

Each of the exhaust gas passage openings 152 is surrounded by a ring-shaped edge region 154 , which is offset relative to the gas guide region 136 of the contact plate 118 along the stack direction 112 and down with the gas guide region 136 via a slope 156 , which is at an inner bending line 158 the edge area 154 and along an outer bending line 160 adjacent to the gas guide area 136 to which the gas guide area 136 is connected (see in particular FIG. 8).

The exhaust gas passage openings 152 of the contact plate 118 enable the passage of exhaust gas to be discharged from the fuel cell units 114 , which contains excess fuel gas and combustion products, in particular water, through the contact plate 118 .

Furthermore, each contact plate 118 is provided with an edge area 162 which surrounds the gas guide area 136 and which is oriented perpendicular to the stacking direction 112 , is offset upwards with respect to the gas guide area 136 along the stacking direction 112 and with the gas guide area 136 via a slope 164 which is along an inner one Bending line 166 is adjacent to the gas guide area 136 and along an outer bending line 168 to the edge area 162 .

The outer edge of the edge region 162 is provided with a connec tion flange 170 , which adjoins the edge region 162 along a bending line 172 and extends downward from the edge region 162 substantially parallel to the stacking direction 112 .

The substantially parallel to the stacking direction 112 aligned outer surface of the connecting flange 170 forms a first connecting surface 174 .

Each of the contact plates 118 is ausgebil det as a sheet metal part, which is formed from a substantially flat, in wesentli Chen rectangular sheet metal layer by embossing and / or deep drawing and by punching or cutting out the fuel gas through openings 142 and the exhaust gas passage openings 152 .

The fluid guide frames 120 are also formed as sheet metal parts from an essentially flat, substantially rectangular sheet metal layer.

As can best be seen from FIG. 6, each fluid guide frame 120 has a substantially rectangular, central passage opening 176 for the passage of the KAE unit 116 of the same fuel cell unit 114 .

This passage opening 176 is surrounded by a substantially flat gas guide region 178 oriented perpendicular to the stacking direction 112 , which comprises two side regions 180 a, 180 b, which are opposite one another at the passage opening 176 .

Several, for example two, substantially circular fuel gas through-openings 182 are formed in the side region 180 a, which allow fuel gas to pass through the fluid guide frame 120 .

In the side area 180 a opposite Seitenbe rich 180 b of the gas guide area 178 are formed several, for example three, substantially circular exhaust gas passage openings 184 which allow the passage of exhaust gas to be removed from the fuel cell units 114 through the fluid guide frame 120 .

The gas guide area 178 of each fluid guide frame 120 is seen at its outer edge with a connecting flange 186 , which adjoins the gas guide area 178 along a bending line 188 and extends downward from the gas guide area 178 substantially parallel to the stacking direction 112 .

The inside of the connecting flange 186, which is oriented essentially parallel to the stacking direction 112 , forms a second connecting surface 190 .

In each case a fluid guide frame 120 and a contact plate 118 together form a housing 192 of a fuel cell unit 114 .

As can be seen from FIGS . 7 to 9, the fluid guide frame 120 and the contact plate 118 of such a housing 192 of a fuel cell unit 114 are fixed to one another at their connecting flanges 186 and 170 and sealed gas-tight to one another.

In this case, surrounds the substantially parallel to the stacking Rich tung 112 aligned connecting flange 186 of the Fluidfüh approximately frame 120 to also aligned substantially parallel to the stacking direction 112 connecting flange 170 of the contact plate 118 such that the first connecting surface of the connecting flange 170 of the contact plate 118 and the second connecting surface 190 at the connection flange 186 of the fluid guide frame 120 face each other.

As can be seen from FIGS. 7 to 9, the lower edge 194 and the second connecting surface 190 of the connecting flange 186 of the fluid guiding frame 120 are welded by means of a weld 196 to the first connecting surface 174 and at the lower edge 198 of the connecting flange 170 contact plate 118 is connected and thus to the connecting flange 170 of the con tact plate 118 fixed.

The weld seam 196 running along the edges of the contact plate 118 and the fluid guide frame 120 ensures a gas-tight closure of the space between the connecting flanges 186 and 170 .

The weld 196 can, for example, run in the laser welding process or be produced in the electron beam process.

As an alternative or in addition to welding, the connection between the connecting flanges 186 and 170 can also be achieved by soldering, in particular by brazing.

Characterized in that the connecting flanges 186 and 170 and in particular the mutually opposing connecting surfaces 174 and 190 are aligned parallel to the stacking direction 112 , the contact plate 118 is accommodated in a kind of sliding fit in the fluid guide frame 120 , so that the connecting flanges 186 and 170 also then without problems can be gas-tightly connected to one another if the distance between the lower edges 194 and 198 along the stacking direction 112 due to manufacturing tolerances in the manufacture of the contact plate 118 and the fluid guide frame 120 or due to assembly tolerances when assembling the fuel cell unit 114 along the edge of the contact plate 118 and the edge of the fluid guide frame 120 varies.

As can best be seen from FIG. 8, ring-shaped supporting elements 200 are arranged in the area of the exhaust gas passage openings 152 , 184 , which with their underside 202 each surround the edge area 154 of a contact plate 118 on the upper side of an exhaust gas passage opening 152 and each have their upper side 204 abut on the underside of an area of the fluid guide frame 120 surrounding an exhaust gas passage opening 184 in the fluid guide frame 120 .

Similar, only in their dimensions of the support elements 200 to the exhaust gas passage openings 152 , 184 under outgoing support elements 200 are arranged between the contact plate 118 and the fluid guide frame 120 in the area of the fuel gas passage openings 142 , 182 .

Such a support element 200 is shown in perspective in FIG. 10 and has the shape of a circular ring with an essentially rectangular cross section. A gas passage from the inside to the outside of the support element 200 (or in the reverse direction) to enable the supporting element 200 with radially aligned, the Abstützele element 200 from the inner side 206 to penetrating to the outer side 208, in the circumferential direction of Abstützele ments 200 spaced apart, substantially cylindrical gas passage channels 210 are provided.

The support elements 200 are used, 192 to hold the contact plate 118 and the fluid guide frame 120 of a casing of a fuel cell unit 114 at a distance from each other and thus to prevent compression of the housing 192 through which, in the assembly of the fuel cell stack assembly 106 acting on the housing 192 clamping force.

The supporting action of the supporting elements 200 plays a special role at the operating temperature of the fuel cell device 100 , which in the case of a high-temperature fuel cell device is in the range from approximately 800.degree. C. to approximately 1000.degree. C., since the yield strength of the steel is used at such operating temperatures which the contact plate 118 and the fluid guide frame 120 are formed, drops to values of less than approximately 10 N / mm ² , so that without the presence of the support elements 200, even small clamping forces would suffice to effect the contact plate 118 and the fluid guide frame 120 of a housing 192 to press against each other.

The support elements 200 can be formed from a metallic material or from a ceramic material.

Instead of a solid support element with gas passage channels 210 , a support element can also be used, which is formed as a porous sintered element from a ceramic and / or a metallic material. Such a sintered element already has sufficient gas permeability due to its porosity, so that such an element does not have to be provided with gas passage channels.

As best seen in FIGS. 8 and 12, Zvi the underside rule of the edge portion 154 of each exhaust passage opening 152 in a contact plate 118 and the top of the gas guide portion 178 of in the stacking direction 112 un ter of the contact plate in question 118 arranged Fluidfüh approximately frame 120 of an adjacent fuel cell unit 114 each have a gas channel seal 212 . Each of the gas channel seals 212 seals the space between the adjacent contact plate 118 and the adjacent fluid guide frame 120 in a gas-tight manner and encloses the respective exhaust passage opening 152 , 184 in the contact plate 118 and in the fluid guide frame 120 in an annular manner.

As can best be seen from FIG. 8, the successive contact plates 118 and fluid guide frames 120 with the support elements 200 and gas channel seals 212 arranged in between in the stacking direction 112 limit several, for example three, exhaust gas channels 214 , into which exhaust gas from the combustion gas spaces 124 of the fuel cell units 114 th through the gas transit channels 210 in the Abstützelemen may occur 200 and the through the gas channel 212 seals in a gastight manner from the oxidant chambers 130 of the fuel cell units are separated material 114th

In a corresponding manner, between the edge regions 144 of the fuel gas passage openings 142 of each contact plate 118 and the fluid guide frame 120, a fuel cell unit 114 arranged in the stacking direction 112 under the relevant contact plate 118 , gas channel seals 212 are arranged, which the fuel gas passage openings 142 and 182 in the contact plate 118 or enclose in the fluid guide frame 120 so that the successive in the stacking direction 112 contact plates 118 and Fluidführungsrah men 120 together with the interposed support elements 200 and gas channel seals 212 several, for example two, fuel gas channels 216 , which form Extend along the stacking direction 112 , from which fuel gas can escape through the gas passage channels 210 in the support elements 200 into the fuel gas spaces 124 of the fuel cell units 114 and which gas-tight from the oxide through the gas channel seals 212 Ationsmittel spaces 130 of the fuel cell units 114 are separated.

The gas channel seals 112 can, for example, each comprise a flat seal made of mica, in particular of phlogopite.

Alternatively or additionally, it can also be provided that the gas channel seals 212 each comprise a gas-tight, electrically insulating coating which is applied as a paste by screen printing or by means of roller coating to the surface of the contact plate 118 or to the surface of the fluid guide frame 120 .

Further, the combustion gas chamber 124 of each fuel cell unit 114 from the oxidizing agent chamber 130 a in the stacking Rich tung 112 arranged above the fuel cell unit 114 in a gastight manner by a fuel gas chamber seal 218 separately, the structure in the following with reference to Fig. 11 will be described in detail lines.

As can be seen from FIG. 11, the substrate 121 of the KAE unit 116 has a compressed outer region 220 which extends along the entire circumference of the substrate 121 and in which the thickness of the substrate 121 is, for example, approximately 20 by a pressing process , the initial thickness, that is, the thickness of the unpressed portion of the substrate 121 , has been reduced.

In this compression process, the porosity of the sub strats 121, the percentage of the gas-filled lumens Vo that is the substrate 121 of the total volume of the substrate 121, Gert verrin in the compressed outer region 220 to almost zero.

In order to achieve this, in the case of a substrate 121 which has a porosity of x%, the thickness in the compressed outer region 220 is preferably reduced to ( 100 - x)% of the initial thickness by the compression process; in the case of a porosity of 80% to 20% of the initial thickness.

The substrate 121 is placed with the underside 222 of the compressed outer region 220 on the fluid guide frame 120 and is gas-tightly connected to the metallic material of the fluid guide frame 120 by a welding process, for example by laser welding, electron beam welding, projection welding or capacitor discharge welding.

By the welding process in the compressed outer region 220 of the substrate 121, a gas-tight zone 224 no longer having porosity is formed, which extends from the lower side 222 to the upper side 226 of the compressed outer region 220 through the compressed outer region 220 of the substrate 121 extends therethrough and forms a gas-tight barrier extending along the entire circumference of the substrate 121 , which gas passage from the edge region 228 lying outside the gas-tight zone 224 into the inner region 230 of the substrate 121 enclosed by the gas-tight zone 224 as well as a gas passage prevented in the opposite direction.

Instead of welding the substrate 121 to the fluid guide frame 120 , the gas-tight zone 224 in the compressed outer region 220 of the substrate 221 can also be formed by soldering the substrate 121 to the fluid guide frame 120 . The solder used is due to the capillary effect into the still existing pores and through channels in the compressed outer region 220 of the substrate 121 so-called and closes these through openings permanently, so that a gas-tight zone 224 extends over the entire height of the compressed outer region 220 ,

As can also be seen from FIG. 11, the gas-tight electrolyte 126 of the KAE unit 116 extends over the edge of the gas-permeable anode 122 and over the edge of the gas-permeable cathode 128 and lies with its underside directly on the top 226 of the compacted outer region 220 of the substrate 121 .

This directly arranged on the substrate 121 outer region 232 of the electrolyte 126 extends to the edge of the substrate 121 so far outward that it covers the gas-tight zone 224 and thus the inner region 230 of the substrate 121 gas-tight from the overlying the electrolyte 126 oxidizing agent space 130 is separated without an additional sealing medium being required for this gas-tight separation.

The outer region 232 of the electrolyte 126 thus forms, together with the gas-tight zone 224 of the compressed outer region 220 of the substrate 121, a gas-tight fuel gas chamber seal 218 which gas-tightly seals the oxidant chamber 130 arranged above the fluid guide frame 120 from the fuel gas chamber 124 arranged below the fluid guide frame 120 separates.

In the embodiment of the combustion gas chamber seal 218 shown in FIG. 11, this seal is in the region between the outer edge of the anode 122 and the gas-tight zone 224 of the compressed outer region 220 of the substrate 121 by the outer region 232 of the electrolyte 126 which extends beyond the anode 122 educated.

As an alternative or in addition to this, it can also be provided that the fuel gas chamber seal 218 comprises a sealing area formed from a sealing compound, which covers the area from the outer edge of the anode 122 to the gas-tight zone 224 in a gas-tight manner.

Such a potting compound can be a glass solder, for example Metallot or include an inorganic paste.

If the fuel gas chamber seal 218 comprises both an electrolyte 126 which extends beyond the gas-tight zone 224 and a potting compound covering this outer region 232 of the electrolyte 126 , this results in a particularly tight and reliable seal of the fuel gas chamber 124 with respect to the oxidant chamber 130 .

As can be seen in particular from FIG. 7, in the assembled state of a fuel cell unit 114, the KAE unit 116 of the fuel cell 114 in question with the substrate 121 rests on the anode-side contact elements 132 a of the contact plate 118 of the fuel cell unit 114 .

Furthermore, the KAE unit 116 rests with the compressed outer area 220 of the substrate 121 on the fluid guide frame 120 of the same fuel cell unit 114 , the uncompressed area of the substrate 121 extending through the passage opening 176 of the fluid guide frame 120 , the substrate 121 by welding or soldering is fixed on the fluid guiding frame 120 and the fluid guide frame 120 by welding at the weld 196 by soldering or its connecting flange 186 to the Ver binding flange 170 of the contact plate 118 on the Kontaktplat te is set 118th

The fuel cell units 114 of the fuel cell block assembly 106 are stacked along the stacking direction 112 so that the cathode-side contact elements 132 b of each contact plate 118 extend to the cathode of the KAE unit 116 of the fuel cell unit 114 arranged underneath it and are in electrical contact with the same ,

The fuel gas passage openings 142 , 182 and the exhaust gas passage openings 152 , 184 along the stack direction 112 of successive fuel cell units 114 are aligned with one another, so as to form the fuel gas channels 216 and the exhaust gas channels 214 .

As can be seen from Fig. 2, opens at the lower end of each of the fuel gas channel 216 in the same Brenngaszuführöff opening 234 , which passes through the lower end plate 108 of the fuel cell lenblockverbunds 106 coaxially to the respective fuel gas channel 216 .

At the end of the fuel gas supply opening 234 facing away from the respective fuel gas channel 216 , a fuel gas branch line 236 is connected, which branches off from a fuel gas supply line 238 which passes through the housing of the fuel cell device 100 in a gas-tight manner and is connected to a fuel gas supply (not shown). which supplies the fuel gas supply line 238 with a fuel gas, for example a gas containing hydrocarbon or pure hydrogen, under an excess pressure of, for example, approximately 50 mbar.

The exhaust gas channels 214 of the fuel cell block assembly 106 each open at their upper ends into an exhaust gas discharge opening 240 which is coaxial with the relevant exhaust gas channel 214 (see FIG. 3) and which passes through the lateral upper end plate 111 and at each end facing away from the respective exhaust gas channel 214 to an exhaust gas branch line 242 is connected.

These exhaust gas branch lines 242 open into a common exhaust gas discharge line 244 (see FIG. 1), which is passed gas-tight through the housing 102 of the fuel cell device 100 and is connected to a (not shown) exhaust gas treatment unit.

During operation of the fuel cell device 100 , the fuel gas flows through the fuel gas supply line 238 , the fuel gas branch lines 236 and the fuel gas supply openings 234 into the two fuel gas channels 216 and is distributed from there through the gas passage channels 210 of the support elements 200 on the fuel gas channel side to the fuel gas spaces 124 of the fuel cell units 114 , which are each enclosed by the contact plate 118 , the fluid guide frame 120 and the KAE unit 116 of the relevant fuel cell unit 114 .

As already described, the fuel gas is at least partially oxidized at the anode 122 of the respective KAE unit 116 delimiting the respective fuel gas chamber 124 .

The oxidation product (water) passes together with excess fuel gas from the fuel gas chambers 124 of the fuel cell units 114 through the gas passage channels 210 of the exhaust gas channel-side support elements 200 into the three exhaust gas channels 214 , from which it passes through the exhaust gas discharge openings 240 , the exhaust gas branch lines 242 and the exhaust gas -Exhaust line 244 is led to the (not shown) exhaust gas treatment unit.

Characterized in that the number of exhaust gas channels 214 is greater than the number of fuel gas channels 216 , a particularly uniform flow through the fuel gas spaces 124 between the rib-shaped contact elements 132 is achieved and the flow resistance is reduced as it flows through the contact field 134 .

In the exhaust gas treatment unit, for example, the reaction product (water) is removed from the exhaust gas stream, and excess fuel gas is passed to the fuel gas supply in order to be fed again to the fuel cell device 100 .

The oxidizing agent (for example, air or pure oxygen) required for the operation of the fuel cell device 100 is supplied to the interior of the housing 102 through the oxidizing agent supply line 104 .

In the interior of the housing 102 , the oxidizing agent is distributed between the oxidizing agent spaces 130 formed between the fuel gas compartments 124 of the fuel cell units 114 , each of which has an adjacent contact plate 118 of a fuel cell unit 114 and through the fluid guide frame 120 and the cathode 128 of the KAE unit 116 th fuel cell unit 114 are enclosed.

In and out of the oxidizing agent spaces, the oxidizing agent passes through the gaps between a respective fluid guide frame 120 of a fuel cell unit 114 and the contact plate 118 of the fuel cell unit 114 following in the stacking direction 112 , insofar as these gaps are not through the support elements 200 , which the fuel gas channels 216 or the exhaust gas channels 214 , are covered.

As already described, 114 are formed oxygen ions from the oxidant to the cathode 128 of the KAE units 116 units of the fuel cells 116 of the fuel cell units migrate through the electrolyte 126 to the anode 122 of the KAE units 114th

Excess oxidant passes from the oxidation medium spaces 130 of the fuel cell units 114 on the side opposite the inlet side of the oxidant and is removed by the oxidant discharge line 105 from the interior of the housing 102 of the fuel cell device 100 .

The direction of flow of the fuel gas and the exhaust gas through the fuel cell device 100 is shown in the drawings, with single arrows 246, the flow direction of Oxida tion means through the fuel cell device 100 with means of double arrows 248th

The flow direction of the oxidizing agent through the oxidizing agent spaces 130 is substantially parallel to the flow direction of the fuel gas through the fuel gas spaces 124 .

In order to fix the consecutive fuel cell units 114 along the stacking direction 112 to one another by external bracing, a plurality of connecting screws 250 (see FIGS. 2 and 3) are provided, which pass through holes 252 in the middle upper end plate 110 of the fuel cell block assembly 106 and on their respective screw head 254 opposite end are provided with an external thread 256 , which is screwed into a threaded bore 258 in the lower end plate 108 of the fuel cell assembly 106 , so that the middle upper end plate 110 and the lower end plate 108 are clamped against each other by the connecting screws 250 and a desired pressing force can be transferred via the end plates 108 , 110 to the central region of the stack of the fuel cell units 114 comprising the contact fields 134 (see FIG. 2).

Furthermore, a plurality of connecting screws 260 are provided, which pass through holes 262 in the lateral upper end plates 111 of the fuel cell block assembly 106 and are provided on their end facing away from the respective screw head 264 with an external thread 266 , which is inserted into a threaded bore 268 in the lower end plate 108 rotates, so that the side upper end plates 111 and the lower end plate 108 are clamped against each other by the connecting screws 260 and a desired pressing force on the end plates 108 , 111 in the area of the fuel gas channels 216 and the exhaust gas channels 214 on the stack of fuel cell units 114 can be transferred is.

The pressing force generated by the external bracing by means of the connecting screws 250 and the middle upper end plate 110 determines the contact pressure with which the contact elements 132 are pressed against the substrate 121 or against the cathode 128 of the adjacent KAE unit 116 .

The contact pressure with which the support elements 200 and the gas channel seals 212 are pressed against the contact plates 118 and the fluid guiding frame 120 , however, is determined - independently of the tension by means of the connecting screws 250 and the middle upper end plate 110 - exclusively by the external prestressing force , with which the side upper end plates 111 by means of the connecting screws 260 are braced against the lower end plate 108 .

The fuel cell block assembly 106 described above is assembled as follows:
First, the individual fuel cell units 114 are assembled by placing a substrate 121 with its compressed outer region 220 on a fluid guide frame 120 and welding or soldering in the manner described above, forming a gas-tight zone 224 in the compressed outer region 220 the fluid guide frame 120 is set. Subsequently, the anode 122 , the electrolyte 126 and the cathode de 128 of the KAE unit 116 are produced on the substrate 121 , for example by plasma spraying, the electrolyte 126 being produced in such a way that it seals the gas-tight zone 224 in the compressed out region sen range 220 of the substrate 121 covered gas-tight to produce the fuel gas chamber seal 218 .

Subsequently, the contact plate 118 of the fuel cell unit 114 is brought into abutment on the side of the substrate 121 facing away from the KAE unit 116 , and the connection flange 170 of the contact plate 118 is connected gas-tight to the connection flange 186 of the fluid guide frame 120 by welding or soldering.

Then the composite fuel cell is composed of the individual fuel cell units 114 106 by GE desired number of stacked fuel cell units 114 along the stacking direction 112 and the fuel cell units 114 by means of the end plates 108, 110, 111 and the ben end plates against each other strained Verbindungsschrau 250, 260 be fixed in position relative to each other.

A second embodiment shown in FIGS. 13 to 15 of a fuel cell device 100 differs from the first embodiment described above only in that support elements 200 'which are arranged between the contact plate 118 and the fluid guide frame 120 of the same fuel cell unit 114 and thus are one Prevent collapse of the housing 192 of the fuel cell unit 114 under the contact pressure, under which the lateral upper end plates 111 and the lower end plate 108 are clamped against one another, not as separate components, but rather in one piece with the contact plate 118 or with the fluid guide frame 120 are trained.

As can be seen from FIGS. 13 and 14, several, for example ten, support elements 200 'are arranged around each of the exhaust duct 214 , which are spaced apart from one another in the circumferential direction of the gas duct 214 , so that the exhaust gas from the fuel gas chamber 124 of the fuel cell unit 114 in question can pass through the gas passages 269 forming spaces between the support elements 200 'into the exhaust duct 214 .

As best seen from the sectional view of FIG. 14, each of the support members 200 'includes an upper portion 270 and a lower portion 272 , the lower portion 272 being integrally formed with the contact plate 118 and one projecting into the exhaust gas passage opening 152 Randbe rich of the contact plate 118 comprises, which has been bent back by bending along a bending line 274 by 180 ° to the edge region 154 of the contact plate 118 .

The upper part 270 of the support element 200 'is formed in one piece with the fluid guide frame 120 and comprises an edge region of the fluid guide frame 120 which projects into the exhaust gas passage opening 184 and which has been bent back along a first bending line 276 by 180 ° to the gas guide region 178 and along a second one Bending line 278 has been bent back on itself by 180 °.

The upper part 270 of the support element 200 'thus comprises two layers arranged one above the other, the lower layer 280 resting flatly with its underside on the upper side of the lower part 272 of the support element 200 '.

The total of three sheet metal layers of the support element 200 'thus form a solid metallic body, which cannot be compressed further by the pressing forces acting on the gas channel seals 212 and the support elements 200 ' and thus the contact plate 118 and the fluid guide frame 120 in the region the exhaust duct 214 keeps a distance from each other and a compression of the Ge housing 192 of the fuel cell unit 114 prevented.

The above-described support elements 200 'corre sponding support elements are also in the area of Brenngaska channels 216 between the contact plate 118 and the fluid guide frame 120 of the same fuel cell unit 114 is arranged.

Otherwise, the second embodiment of a fuel cell device 100 corresponds in terms of structure and function to the first embodiment, to the above description of which reference is made.

Claims (8)

1. Fuel cell unit for a fuel cell block composite which includes a plurality of Brennstoffzellenein units (114) disposed along successive follow a stacking direction (112), wherein the Brennstoffzellenein unit (114) comprises a housing (192) with a first housing part (118) and a second housing part ( 120 ), which are connected to one another in a substantially gas-tight manner, and wherein the first housing part ( 118 ) has a first connecting surface ( 174 ) on which the first housing part ( 118 ) is fixed to the second housing part ( 120 ) characterized in that the first connecting surface ( 174 ) is aligned substantially parallel to the stacking direction ( 112 ). 2. Fuel cell unit according to claim 1, characterized in that the first connecting surface ( 174 ) is arranged on a first connecting flange ( 170 ), the first connecting flange ( 170 ) along a bend never ( 172 ) to an area ( 136 ) of the first Adjacent housing part ( 118 ), which is oriented substantially perpendicular to the stacking direction ( 112 ), and extends from this area ( 136 ) of the first housing part ( 118 ) substantially parallel to the stacking direction ( 112 ). 3. A fuel cell unit according to claim 2, characterized in that the first connecting flange ( 170 ) surrounds the area ( 136 ) of the first housing part ( 118 ) oriented substantially perpendicular to the stacking direction ( 112 ). 4. Fuel cell unit according to one of claims 1 to 3, characterized in that the second housing part ( 120 ) has a second connecting flange ( 186 ) which is along a bending line ( 188 ) adjacent to an area ( 178 ) of the second housing part ( 120 ), which is oriented essentially to the stacking direction ( 112 ), and which extends from this region ( 178 ) of the second housing part ( 120 ) essentially parallel to the stacking direction ( 112 ). 5. Fuel cell unit according to claim 4, characterized in that the second connecting flange ( 186 ) has a free edge ( 194 ) on which the second connec tion flange ( 186 ) with the first housing part ( 118 ) is connected ver. 6. Fuel cell unit according to claim 2, characterized in that the first connecting flange ( 170 ) has a free edge ( 198 ) on which the first connec tion flange ( 170 ) is connected to the second housing part ( 120 ). 7. Fuel cell unit according to one of claims 1 to 6, characterized in that the first housing part ( 118 ) and the second housing part ( 120 ) sen by welding, in particular by laser welding, and / or by soldering, in particular by brazing, substantially gas-tight with each other are connected. 8. Fuel cell block assembly, comprising a plurality of fuel cell units according to one of claims 1 to 7, which follow one another along the stacking direction ( 112 ).