Patent Publication Number: US-2006003194-A1

Title: Fuel cell pack and power producing device comprising said fuel cell pack

Description:
The present invention relates to a fuel cell pack and also to a power-producing device comprising at least one such fuel cell pack.  
      Conventionally, such a power-producing device comprises at least one fuel cell pack, each of which includes a succession of elementary cells arranged beside one another. Each of these cells defines an anode compartment in which the oxidation of hydrogen takes place, and also a cathode compartment in which the oxygen in air is reduced, with water being produced.  
      Furthermore, an ion-exchange membrane physically separates the anode and cathode compartments of a cell in question, these compartments also being connected by means of an external electrical circuit.  
      The cell pack is additionally provided with distribution means allowing the various fluids to be fed in and discharged.  
      Thus, the anode compartment of each cell is placed in communication with a hydrogen inlet line and also with a line for discharging the consumed hydrogen. The latter is mixed with a fraction of water, produced at the cathode, which has crossed the aforementioned separation membrane.  
      Similarly, the cathode compartment is provided with an air inlet pipe and also with a pipe for discharging this oxygen-depleted air mixed with water.  
      In order for these fluids to be fed into and discharged from the fuel cell pack, the power-producing device is provided with various members allowing distribution of these fluids.  
      Thus, in the known prior art, there are provided a plurality of disparate connectors cooperating with fluid inlets and outlets which are present on a number of sides of the cell pack. Moreover, valves enable these various fluid circuits to be closed so as to isolate this cell pack.  
      However, in the event of failure of a cell pack, it is important to be able to disconnect it from the other elements of the power-producing device in order to provide a rapid replacement thereof.  
      It will be appreciated that, in the prior art, this operation of disconnecting the cell pack is particularly long and tedious to implement. Thus, the phases of fitting and removing this pack, which are long and tedious, constitute a major portion of the maintenance costs for the power-producing device.  
      Moreover, this substantial maintenance time is accompanied by a dead period in which the installation is immobilized, during which period the power-producing device based on a fuel cell cannot be used. This constitutes an economic limitation, the impact of which is notable.  
      The invention proposes to overcome the disadvantages of the prior art mentioned above. It aims particularly to provide a fuel cell pack whose overall maintenance can be achieved much more readily and quickly than by the solutions of the prior art, particularly by facilitating the operations of fitting/removing the cell pack, for example with regard to changing elementary cells.  
      To this end, the subject of the invention is a fuel cell pack intended to be integrated into a power-producing device, this cell pack comprising a plurality of elementary cells and also fluid distribution means which make it possible to supply each cell with two input fluids, typically hydrogen and air, and also to discharge from these cells two output fluids, typically hydrogen and oxygen-depleted air, these distribution means being able to be connected to a fluid distribution system belonging to said power-producing device, in which fuel cell pack the distribution means comprise, on one side of the cell pack, a series of first valve elements which are able, in the assembled configuration, to cooperate with a series of second valve elements borne by the fluid distribution system.  
      According to other characteristics of the invention: 
          the first valve elements are arranged on the same face of the cell pack;     the valve elements have main directions which are parallel to one another.        

      According to one aspect of the invention, the cell pack combines, at one end, at least two pairs of fluid distribution connectors which are able to cooperate with at least two pairs of stationary, corresponding connectors arranged on the fluid distribution system of the power-producing device.  
      Another subject of the invention is a power-producing device comprising at least one cell pack and also a fluid distribution system which is able to supply the or each cell pack with two input fluids and also to discharge at least two output fluids coming from this cell pack, this distribution system being able to be connected to external circuits for supplying the input fluids and also for discharging the output fluids, wherein the or each cell pack is as defined above and herein said power-producing device also comprises second valve elements, each second valve element being able to cooperate with a corresponding first valve element with which said cell pack is provided.  
      According to other characteristics of the invention: 
          the fluid distribution system comprises a support member, in particular a plate structure, on which are mounted various members for distributing the input and output fluids and which is advantageously made of a plastic by injection molding or compression molding;     the support member has integrated channels cut into it which allow the various fluids to circulate.       

    
    
      The invention will be better understood on reading the description below, which is given purely by way of nonlimiting example and with reference to the appended drawings, in which:  
       FIG. 1  is an exploded perspective view illustrating the various elements constituting an embodiment of a power-producing device based on a fuel cell, according to the invention;  
       FIG. 1A  is a perspective view of the power-producing device of  FIG. 1 , once mounted, seen from a different angle;  
       FIGS. 2 and 3  are views in longitudinal section illustrating two valve elements belonging to the power-producing device of the preceding figures, in two different positions; and  
       FIG. 4  is a schematic side view illustrating a power-producing device based on a fuel cell, according to a variant embodiment of the invention. 
    
    
      The power-producing device, as illustrated in  FIGS. 1 and 1 A, comprises a fuel cell pack denoted overall by the reference  2 , for example of the type described in the French application filed on Mar. 6, 2002, under number 02 02843, the content of which is incorporated herein by reference.  
      The cell pack  2  is able to be mounted at its base  4  on a support plate  6  via four centering pegs  5  mounted on the support plate  6 . This support plate  6  also houses, in the example represented, a compressor  8 , an electrical box  10  provided with its control  12 , an air/air exchanger  14 , a liquid/gas separator  16 , a hydrogen input pressure-reducing valve  18  and also a solenoid valve  20 . All these elements, which are of a type known per se, are fixed to the support plate  6  by any suitable means.  
      The device additionally comprises a fluid connection unit  22 , also mounted on the support plate  6 , provided with several, typically four, valve elements or closable connectors  24 , to  244  arranged in a defined pattern on one face (the front face in  FIG. 1 ) of this unit  22 , at the outlet of four orifices in this unit. These various valve elements will be described in more detail hereinafter.  
      The plate  6  is provided with various orifices which are placed in communication with circuits (not shown) allowing the various fluids to be admitted and discharged.  
      Moreover, some of the elements  8 ,  14 ,  16 ,  18  and  20  are placed in mutual fluid communication by way of channels (not shown) which are formed in the support plate.  
      Consequently, air is admitted into a corresponding inlet orifice provided in the plate  6 . It then circulates inside this plate, enters the compressor  8  and then leaves the latter to circulate once more within the plate  6 , after it has passed through the exchanger  14 .  
      Next, this input air is admitted into the separator  16 , leaves therefrom so as to travel within the plate  6 , and is then finally brought into the unit  22 . It then emerges into a suitable orifice in this connection unit  22  so as to be admitted into the cell pack  2  for the purpose of supplying its various cells with air. Then, the oxygen-depleted air discharged from these cells is once more directed toward the unit  22  via another orifice designated for this air output. This depleted air then circulates inside the plate  6 , is admitted into the exchanger  14 , leaves the latter, circulates once more within the plate  6 , and is finally discharged from the latter through an ad hoc orifice (not shown).  
      The hydrogen is admitted similarly into the plate  6  through an inlet orifice and then emerges into the connection unit  22 . It leaves the latter, via a designated orifice, so as to be admitted into the cell pack  2  for the purpose of supplying the various cells of the latter with hydrogen. Then, the output hydrogen coming from these cells is discharged from the cell pack  2  and enters the connection unit  22  through another designated orifice provided in the latter. This hydrogen then travels inside the plate  6 , within the solenoid valve  20 , leaves therefrom to circulate once more within the plate, and is finally discharged from this plate via a corresponding outlet orifice (not shown).  
      The fuel cell pack is for its part equipped at its end with a plate  26  allowing it to be retained mechanically. This plate  26  also performs a fluid connection function. To be specific it is provided, in the vicinity of its lower end, with four closable connectors or valve elements  30   1  to  30   4  ( 30   i ) distributed spatially in a pattern which is identical to that of the valve elements  24   i  of the unit  22 . The valve elements  30   i  are placed at the outlet of four orifices, each of which is intended for the admission or discharge of air or of hydrogen into or from the cell pack. More precisely, these four orifices are placed in communication with means formed in the cell pack  2  which allow fluid to be distributed to and from the various cells  32  of this pack. These distribution means thereby ensure, in a manner known per se, that hydrogen is fed in and discharged and also that air is fed in and oxygen-depleted air is discharged.  
       FIGS. 2 and 3  illustrate two valve elements  24 , and  301 , belonging respectively to the unit  22  and to the connection plate  26  with which the cell pack  2  is equipped. It should be understood that the valve elements  24   2  to  24   4  are, for example, analogous to that one  24   1  represented, whereas the valve elements  30   2  to  30   4  are analogous to that one  30   1  represented.  
      The valve element  24   1  comprises a hollow body  34  mounted in a wall (represented partially) of the unit  22 . This body, which comprises an end section  36 , houses an intermediate partition  38 , forming a seat. Furthermore, openings (not shown) are made both in the end section  36  and in the partition  38  in order to ensure selective fluid flow. An O-ring seal  40  is mounted at the periphery of the partition  38 , facing the end section  36 . Finally, the valve element  24 , is equipped with a moving stem  42  having a peripheral ring  44  which can bear against the seal  40 .  
      Finally, a spring  46  is provided, a first end of which bears against the end section  36 , while its other end bears against the ring  44 . This spring tends to return the latter  44  against the seal  40 , namely into the closed position of the valve assembly  241 .  
      The valve element  30   1  also comprises a hollow body  54  which is able to fit over the free end of the body  34  of the element  24   1 , with interposition of a peripheral seal  35 . The other element  30   1  thus forms the female part of the valve formed by the two elements  24   1  and  30   1 .  
      The body  54 , which comprises an end section  56 , houses a partition  58 , forming a seat, in which an O-ring seal  60  is accommodated. The element  30   1  also includes a stem  62  having an outer ring  64  which can bear against the seal  60 .  
      Openings (not shown) are made in the end section  56  and in the partition  58  in order to allow selective fluid flow.  
      Finally, a spring  66  is provided, one end of which bears against the end section  56 , while its other end bears against the ring  64 . This spring  66  tends to return the ring  64  against the seal  60 , that is to say into the closed position of the valve element  30   1 .  
      When the cell pack  2  is not mounted on the support plate  6 , each valve element  24   1  and  30   1  is in its closed position, illustrated in  FIG. 2 . Consequently, it is not possible for any fluid to be discharged either from the cell pack  2  or from the fluid connection unit  22 . Furthermore, any input of external air is avoided.  
      If it is wished to bring the power-producing device into service, the cell pack  2  has to be arranged on the support plate  6  and, more precisely, the connection unit  22  has to be engaged with the connection plate  26 .  
      To this end, the cell pack  2  is brought together with the connection unit  22 , assumed to be fixed, in the main direction of the valve elements (referenced A in  FIGS. 2 and 3 ), namely the main direction of the hollow bodies  34  or  54 . It will be noted that such an operation is made possible by virtue of the fact that, on the one hand, the main axes of the valve elements  30   1  to  30   4  are parallel to one another and that, on the other hand, the main axes of the valve elements  24   1  to  24   4  are also parallel to one another.  
      During the bringing-together operation mentioned above, the free end of the hollow body  34  enters the inner volume of the hollow body  54 , while the two stems  52  and  62  are pushed back toward a facing end wall,  36  or  56  respectively, in the direction of the arrows F.  
      The rings  44  and  64  are thus moved away from the seals  40  and  60 , which releases the openings made in the partitions  38  and  58  and also those made in the end sections  36  and  56 . The various fluids are then able to flow within the two valve elements, in the direction of the arrows f.  
      This therefore guarantees that the cells  32  are supplied simultaneously with air and with hydrogen and also that oxygen-depleted air and hydrogen are discharged from the cell pack  2 .  
      By way of a variant (not shown), the valve element  24 , mounted on the connection unit  22  may have only one fluid flow position. In this case, this valve element is fixed, which is advantageous in economic terms since this measure provides a reduction in the manufacturing costs.  
      It should be noted that such a possibility is not necessarily detrimental to the sound operation of the power-producing device, particularly when such a fixed valve element is intended to receive oxygen-depleted air discharged from the cell pack.  
       FIG. 4  illustrates a variant embodiment of a power-producing device according to the invention.  
      Several, in this case three, fuel cell packs which are, for example, identical and are allocated the references  102 ,  102 ′ and  102 ″ are thus provided.  
      The power-producing device also includes a support plate  106  which is permanently fixed, for example against a wall  107 . This plate  106  is provided with the various elements  8  to  20  described with reference to  FIGS. 1 and 1 A but not represented in this  FIG. 4 .  
      The support plate  6  is additionally equipped with three series of four valve elements. There can thus be seen four upper valve elements, of which only two  124   1  and  124   2  are represented, four intermediate valve elements, of which only two  124 ′ 1 , and  124 ′ 2  are represented, and also four lower valve elements, of which only two  124 ″ 1  and  124 ″ 2  are represented.  
      These various valve elements, which are similar to those  24   1  to  24   4 , have main axes which are parallel to one another.  
      Furthermore, the upper cell pack  102  is provided with four valve elements, of which only two  130   1  and  130   2  are represented. These valve elements, which are similar to those  30   1  to  30   4 , are able to cooperate with the upper valve elements, in particular  124 , and  1242 , with which the support plate  106  is provided.  
      The intermediate cell pack  102 ′ is also provided with four valve elements, of which only two  130 ′ 1  and  130 ′ 2  are represented. These valve elements, which are similar to those  30   1  to  30   4 , are able to cooperate with the intermediate valve elements, in particular  124 ′ 1  and  124 ′ 2 , with which the support plate is provided.  
      Finally, the lower cell pack  102 ″ is provided with four valve elements, of which only two  130 ″ 1  and  130 ″ 2  are represented. These various valve elements, which are similar to those  30   1  to  30   4 , are able to cooperate with the lower valve elements, in particular  124 ″ 1  and  124 ″ 2 , with which the support plate  106  is provided.  
      Each cell pack  102 ,  102 ′ and  102 ″ is, moreover, equipped with a gripping handle  103 ,  103 ′ and  103 ″. Finally, guide means, such as slideways (not shown), may advantageously be provided in order to permit simple positioning of the cell packs when they are being mounted on the support plate  106 .  
      The power-producing device represented in  FIG. 4  is particularly convenient to use. Thus, the user is able to disconnect from the support plate  106  one or other of the cell packs  102 ,  102 ′ or  102 ″ in the event of failure. Such an operation is additionally facilitated by the presence of the handles  103 ,  103 ′ and  103 ″.  
      The invention makes it possible to achieve the objectives mentioned above.  
      Thus, the or each fuel cell pack with which the power-producing device is equipped can be disconnected in a particularly simple and speedy manner. Consequently, it is much simpler to maintain this power-producing device than in the prior art.  
      Simplifying maintenance in this way additionally guarantees an increase in productivity. Specifically, since the cell pack is put out of service for a shorter length of time, its effective operating time is correspondingly prolonged.  
      According to one characteristic of the invention, the support plate  6  or  106 , additionally providing circulation of the fluids, is made of a plastic by injection molding or compression molding. It is also conceivable for the major part of the various valve elements with which the cell pack or the fluid connection unit are equipped to be made of such a plastic. In this regard, only the springs, referenced  46  and  66  in  FIGS. 2 and 3 , are then formed of another material, particularly metal.  
      This use of a plastic makes it possible to very significantly reduce the various manufacturing costs associated with the power-producing device. Furthermore, this ensures particularly easy maintenance given that it is remarkably simple to take hold of and remove the various constituent elements.