JP4389456B2 - Cell voltage measuring part structure of solid polymer electrolyte fuel cell - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a structure capable of reducing the thickness of a gas separator of a solid polymer electrolyte fuel cell having a cell voltage measurement function, and enabling the downsizing and assembly of a solid polymer fuel cell.
[0002]
[Prior art]
A solid polymer electrolyte fuel cell is formed by sandwiching a thin film electrode assembly formed by sandwiching both sides of a solid polymer ion exchange thin film with an electrode made of a porous conductor between two conductive gas separators. In this gas separator, a fuel gas flow path and an oxidant gas flow path are formed in a portion in contact with the thin film electrode assembly to constitute a set of fuel cell single cells. Then, by positioning the thin film electrode assembly on the upper and lower surfaces of one gas separator, a plurality of single cells can be stacked in series, and a fuel cell stack can be configured.
[0003]
A fuel gas such as hydrogen is passed through the fuel gas flow path of the anode side gas separator sandwiching a thin film electrode assembly having an ion exchange function, and an oxidant gas such as air containing oxygen is passed through the oxidant gas flow path of the cathode side gas separator. Thus, the hydrogen ions in the fuel gas permeate through the solid polymer ion exchange thin film and move to the cathode, and the electrons pass through the external load connected between the anode side gas separator and the cathode side gas separator. By moving to the separator, an electromotive force is generated and a current flows.
[0004]
In a fuel cell stack in which a plurality of single cells are stacked in series, the single cells are connected in series. Therefore, even if one of the single cells constituting the fuel cell stack becomes unable to generate power due to damage to the solid polymer ion exchange thin film, etc. The power generation as a whole fuel cell stack becomes impossible.
[0005]
In addition, when one unit cell in the fuel cell stack becomes unable to generate power, if the cause is due to damage to the solid polymer ion exchange thin film, the fuel gas and oxidant gas are mixed inside the fuel cell stack. Therefore, it is necessary to immediately stop the operation and replace the unit cell that cannot generate electricity. However, since conventional power extraction is performed only at the output terminal of the fuel cell stack, it is difficult to confirm which single cell cannot generate power from the outside.
[0006]
For this reason, in a system using a recent fuel cell stack, an output terminal is provided for all of the conductive gas separators constituting the fuel cell stack, and the voltage between the anode gas separator and the cathode gas separator of each single cell is set. A structure has been proposed for measuring and confirming whether all single cells are generating electricity normally.
[0007]
As a specific structure, in a fuel cell stack of a solid polymer electrolyte fuel cell, as an output terminal for measuring a voltage between an anode and a cathode gas separator, a screw hole is formed on a side surface of the gas separator as shown in FIG. Generally, a terminal having a lead wire connected to the screw hole is screwed. Further, as shown in FIG. 6, there is also used a method in which a part of the gas separator is protruded to the outside to constitute an output terminal provided with a screw hole, and a terminal having a lead wire connected to the screw hole is connected by a screw.
[0008]
[Problems to be solved by the invention]
By the way, the resin-impregnated carbon, which is the material of the gas separator of the solid polymer electrolyte fuel cell, has a drawback that it is difficult to perform machining such as screw hole machining, and it takes time to process. When the screw holes are formed toward the inside of the gas separator, there is a problem that the mechanical strength of the gas separator is lowered.
[0009]
Also, when an output terminal such as a screw hole is provided on the side of the gas separator, the smaller the screw hole, the thinner the gas separator can be made, but the fixing screw becomes smaller as the screw hole becomes smaller in diameter. If it is too much, the screw tightening work by the driver becomes difficult, and it takes time to work and the workability is lowered.
[0010]
For this reason, there is a limit to the reduction in the diameter of the screw, and the thickness of the gas separator is inevitably set to a certain thickness or more. Therefore, it is difficult to reduce the thickness of the gas separator. There is also an adverse effect of increasing the size, and it is difficult to downsize the fuel cell stack and reduce material costs.
[0011]
On the other hand, when fixing a voltage measuring lead wire with a tightening nut by protruding a part of the gas separator, it is necessary to provide a space for the height of the tightening nut. The workability is poor, the cost is increased, and the material cost of the gas separator is increased.
[0012]
Furthermore, in order to reduce the manufacturing cost of the gas separator, in the case of the method of creating a gas separator by press molding, it is conceivable to mold a screw hole having a spiral shape on the side surface portion of the gas separator with a mold. It is impossible to mold a hole with a mold alone, and it is necessary to machine a screw hole after machining the gas separator by molding, leading to an increase in processing time and manufacturing cost. .
[0013]
Even when a metal material is used as a gas separator, the problem of the thickness of the gas separator, the problem of lowering mechanical strength, and the problem of restrictions on the mold are not different from those of the resin-impregnated carbon described above. It was.
[0014]
[Means for Solving the Problems]
The present invention solves the above-mentioned problem. A thin film electrode assembly 3 formed by sandwiching both sides of a solid polymer ion exchange thin film 1 with an electrode 2 and a fuel on both sides of the thin film electrode assembly 3 are sandwiched. A gas separator 4 having conductivity that forms a gas flow path 4a and an oxidant gas flow path 4b, and the thin film electrode assembly 3 and the gas separator 4 sandwiched between the gas separators 4 constitute a single cell 5; In the solid polymer electrolyte fuel cell constituting the fuel cell stack 6, a plurality of the single cells 5 are stacked in series, and the plurality of single cells 5 are formed in communication with the outside between the plurality of gas separators 4 that are overlapped. A slit 7 and a cell voltage measuring line 8 fitted to the slit 7 with the conductive surfaces facing outward are provided, and the cell voltage measuring line 8 is fitted to the slit 7 to adjust the voltage of each single cell 5. taking measurement Those having an elephant.
[0015]
Further, a concave portion 7a is formed by die molding on one of the upper and lower surfaces continuous with the side surface of the gas separator 4 or both upper and lower surfaces, and the slit 7 is a side surface of the fuel cell stack 6 when the single cells 5 are stacked. By forming the recess 7a of the gas separator 4 appearing in FIG.
[0016]
The cell voltage measuring line 8 is composed of two card-type electric wires 8a and 8b having conductive surfaces facing outward, and an insulating elastic body 9 is sandwiched between the card-type electric wires 8a and 8b. Therefore, it is no longer necessary to sandwich the cell voltage measurement line 8 while stacking the single cells 5.
[0017]
The elastic body 9 sandwiched between the two card-type electric wires 8a and 8b is formed so as to protrude from the tip or side end of the card-type electric wires 8a and 8b, and the protruding portion of the elastic body 9 And a convex stopper 11 corresponding to the concave stopper 10 provided on the elastic body 9 is provided in the slit 7 of the gas separator 4, and the concave stopper 10 and the convex stopper 11 are fitted to each other. As a result, the cell voltage measurement line 8 is not easily disconnected.
[0018]
[Action]
In the solid polymer electrolyte fuel cell, a fuel gas and an oxidant gas are respectively provided in a fuel gas channel 4a and an oxidant gas channel 4b on both sides of a thin film electrode assembly 3 sandwiched by a plurality of stacked gas separators 4 respectively. A potential is generated between the two gas separators 4 in contact with the thin film electrode assembly 3. Since a power generation function is created between the two gas separators 4 in contact with the thin film electrode assembly 3, a fuel cell stack 6 that can obtain a desired voltage can be configured by stacking a large number of gas separators 4.
[0019]
A slit 7 communicated with the outside is provided on the side surface of the overlapped gas separator 4. By inserting the cell voltage measurement line 8 into the slit 7, the conductive surfaces provided outward of the cell voltage measurement line 8. Is in contact with two gas separators 4 having a potential difference, and the potential difference between the gas separators 4 can be confirmed by measuring the potential difference at the other end of the cell voltage measurement line 8.
[0020]
【Example】
The present invention will be described with reference to the drawings showing embodiments. 1 is a solid polymer ion exchange thin film, which is a component of a fuel cell, 2 is an electrode disposed on both sides of the solid polymer ion exchange thin film 1, and 3 is a solid polymer. A thin film electrode assembly 4 in which the ion exchange thin film 1 and the electrode 2 are integrally formed is sandwiched between both sides of the thin film electrode assembly 3 in order to supply fuel gas or oxidant gas to the electrode 2 of the thin film electrode assembly 3. The material of the gas separator 4 is made by molding using resin-impregnated carbon.
[0021]
Reference numeral 5 denotes a single cell as a basic power generation element of a fuel cell configured by sandwiching the thin film electrode assembly 3 between two gas separators 4, and 6 denotes a fuel cell stack configured by laminating a plurality of the single cells 5. A predetermined voltage can be obtained as a fuel cell by stacking a plurality of single cells 5.
[0022]
4a is a fuel gas passage for supplying the fuel gas formed between the gas separator 4 and the electrode 2 on one side to the thin film electrode assembly 3, and 4b is formed between the other gas separator 4 and the electrode 2. This is an oxidant gas flow path for supplying an oxidant gas to the thin film electrode assembly 3. A fuel gas supply pipe 12 is connected to the inlet side of all the fuel gas flow paths 4 a in the fuel cell stack 6 to supply fuel gas, and 12 a is a fuel gas flow path 4 a in the fuel cell stack 6. A fuel gas exhaust pipe communicated with the exhaust outlet side, 13 is an oxidant gas supply pipe for communicating with the inlet side of all the oxidant gas flow paths 4b in the fuel cell stack 6 and supplies an oxidant gas, 13a It is an oxidant gas exhaust pipe communicating with the exhaust outlet side of all the oxidant gas flow paths 4b in the fuel cell stack 6.
[0023]
A fuel gas is supplied from a fuel gas supply pipe 12 to the fuel gas flow path 4a on the gas separator 4, and the fuel gas flowing on the fuel gas flow path 4a is converted into hydrogen ions and electrons on the thin film electrode assembly 3. The hydrogen ions pass through the thin film electrode assembly 3 and move to the cathode. On the other hand, oxidant gas is supplied from the oxidant gas supply pipe 13 to the oxidant gas flow path 4b on the gas separator 4 on the opposite side across the thin film electrode assembly 3, and oxygen in the oxidant gas is Hydrogen ions that have permeated through the thin film electrode assembly 3 and flowed from the gas separator 4 on the fuel gas channel 4a side toward the gas separator 4 on the oxidant gas channel 4b side via an external circuit (not shown). Oxidation reaction is performed by electrons to generate water. This reaction is continuously performed by continuing to supply the fuel gas and the oxidant gas, so that a current continues to flow in the external circuit, and the current obtained at this time is taken out and used as DC electric energy. be able to. The fuel gas and oxidant gas that have not been used for the oxidation reaction are exhausted to the outside through the fuel gas exhaust pipe 12a and the oxidant gas exhaust pipe 13a.
[0024]
Since the fuel cell that operates in this way forms the fuel cell stack 6 in which the single cells 5 that are the basic configuration are stacked in series to obtain a predetermined DC voltage, even one of the plurality of single cells 5 can be obtained. If power generation becomes impossible, the power generation capability expected as the whole of the fuel cell stack 6 becomes impossible.
[0025]
Further, when the power generation of the single cell 5 becomes impossible due to the damage of the thin film electrode assembly 3, there is a possibility that the fuel gas and the oxidant gas are mixed inside the single cell 5, and the fuel gas If the gas and oxidant gas are mixed, there is a risk of explosion and combustion. Therefore, when the voltage is abnormal, it is necessary to immediately stop the supply of fuel gas and oxidant gas. There is a need.
[0026]
Thus, in the fuel cell power generation system, it is necessary to always check whether the single cells 5 forming the fuel cell stack 6 generate normal voltages between the gas separators 4 in order to generate power safely.
[0027]
The present invention solves the above problems. As shown in FIGS. 1 and 2, 7a is a recess formed in the overlapping portion of the gas separator 4 while communicating with the outside, and 7 is a recess 7a of the gas separator 4. A slit formed on the side surface of the fuel cell stack 6 so as to communicate with the outside by means of a cell voltage measuring line 8 with the conductive surfaces facing each other so as to contact the gas separator 4 inside the slit 7, When the cell voltage measurement line 8 is fitted into the slit 7, the inside of the slit 7 of each of the gas separators 4 and the conductive surface facing the outside of the cell voltage measurement line 8 can come into contact with each other.
[0028]
Fuel gas and oxidant gas are respectively supplied to the fuel gas flow path 4a and the oxidant gas flow path 4b of the gas separator 4, and between the two gas separators 4 with the thin film electrode assembly 3 interposed therebetween. A potential difference has occurred. The cell voltage measurement lines 8 fitted in the slits 7 and sandwiched between the gas separators 4 have the same electric potential as the gas separator 4 at the contact surfaces of the cell voltage measurement lines 8. By measuring the electromotive force of the single cell 5, it is possible to detect a power generation failure of the single cell 5 constituting the fuel cell stack 6. For this reason, the supply of the fuel gas and the oxidant gas to the fuel cell stack 6 mixed with the failed single cell 5 is stopped, and the failed single cell 5 is repaired.
[0029]
As described above, since the slit 7 is formed on the side surface of the gas separator 4, the cell voltage measuring line 8 having conductive surfaces facing each other can be inserted into the slit 7 so that the output voltage of the single cell 5 can be measured. Thus, the workability of mounting the cell voltage measurement line 8 is remarkably improved as compared with the conventional screw fixing. Moreover, since it is not necessary to provide a screw hole with poor processability in each gas separator 4 as in the prior art, and only the slit 7 is formed between the two gas separators 4, the thickness can be reduced. The fuel cell stack 6 can be downsized.
[0030]
In addition, since the slit 7 can be formed at the same time when the gas separator 4 is formed by molding, a special operation for attaching the cell voltage measuring line 8 such as a screw hole that had to be performed by post-processing. The process became unnecessary, and the working time and manufacturing cost could be reduced. In addition, parts such as screws are not required, the number of parts is reduced, and material costs can be reduced.
[0031]
The recesses 7a may be formed on the overlapping surfaces of the gas separators 4 stacked one above the other. However, even if they are not formed on both surfaces in this way, as shown in FIG. The recess 7a may be formed. Also at this time, if the two gas separators 4 are overlapped, the slit 7 can be formed, and the electromotive force of the single cell 5 can be measured by the cell voltage measuring line 8. If the recess 7a constituting the slit 7 is on one side, the mold for molding the gas separator 4 can be easily manufactured because one of the recesses 7a can be omitted.
[0032]
8a and 8b are two card-type electric wires having a conductive surface constituting the cell voltage measuring line 8, and 9 is an insulation for sandwiching and integrating the two card-type electric wires 8a and 8b. When the cell voltage measurement line 8 is inserted into the slit 7 after the fuel cell stack 6 is formed, the elastic body 9 can be deformed to insert the elastic body. Since the conductive surface of the card-type electric wires 8a and 8b is strongly pressed against the gas separator 4 in the slit 7 by the restoring force of 9, reliable voltage measurement is possible and the effect of preventing the cell voltage measurement line 8 from coming off is obtained. Can do.
[0033]
Further, as shown in FIG. 3, 10 is a concave stopper formed on the upper and lower surfaces of the elastic body 9 having an insulating property further protruded from the tips of the card-type electric wires 8a and 8b, and 11 is a concave portion 7a formed on the gas separator 4. The convex stopper 11 of the gas separator 4 is structured to be fitted with the concave stopper 10 of the elastic body 9, and the cell voltage measuring line 8 is a slit formed on the side surface of the fuel cell stack 6. 7 is pushed. For this reason, the elastic body 9 is inserted into the slit 7 together with the card-type electric wires 8a and 8b while being deformed, the convex stopper 11 and the concave stopper 10 are fitted, and the restoring force of the elastic body 9 is the card type. Since the conductive surfaces of the electric wires 8a and 8b act in the direction of pressing the inner surface of the slit 7 formed between the two gas separators 4, the cell voltage measuring line can be firmly attached as when using a conventional fixing screw. The omission prevention performance of No. 8 could be further improved.
[0034]
【The invention's effect】
As described above, in the present invention, the slit 7 communicated to the outside between the two gas separators 4 in order to measure the electromotive force of the thin film electrode assembly 3 constituting the single cell 5 of the solid polymer electrolyte fuel cell. The electromotive force can be easily measured by providing the slits 7 with the electrically conductive surfaces of the cell voltage measuring line 8 facing each other in close contact with the gas separator 4. Further, since the gap between the slits 7 can be narrowed, the gas separator 4 of the solid polymer electrolyte fuel cell can be made thin, and the fuel cell stack 6 in which the single cells 5 are stacked and integrated is realized in a compact manner. did it.
[0035]
In addition, the cell voltage measuring line 8 does not need to be directly fixed to the gas separator 4 using a fixing screw as in the prior art. In order to fix the cell voltage measuring line 8 to the fuel cell stack 6, it is difficult to shorten the working time. There is no need to do this, and workability is improved.
[0036]
The recesses 7a provided on either or both sides of the side surface of the gas separator 4 forming the slit 7 for inserting the cell voltage measuring line 8 are also provided when the gas separator 4 is manufactured by molding. Since it can be formed easily and does not require screw holes by machining, it can be manufactured at a lower cost.
[0037]
The cell voltage measuring line 8 is constructed by sandwiching an insulating elastic body 9 between the two card-type electric wires 8a and 8b, so that the cell voltage measuring line 8 is connected after the fuel cell stack 6 is assembled. Even when the fuel cell stack 6 is inserted into the slit 7, the elastic body 9 between them can be compressed so that it can be connected to the correct position, and the cell voltage measurement line 8 does not easily fall off.
[0038]
The elastic body 9 sandwiched between the two card-type electric wires 8a and 8b constituting the cell voltage measuring line 8 is provided with a concave stopper 10 at a tip thereof or a portion protruding from the card-type electric wires 8a and 8b at the side ends. In addition, by providing a convex stopper 11 fitted in the concave stopper 10 in the slit 7 of the gas separator 4, this cell voltage measurement is performed after the cell voltage measurement line 8 is inserted into the slit 7. The wire 8 is more difficult to come off.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing a single cell part of a fuel cell according to the present invention.
FIG. 2 is a perspective view showing a voltage measurement unit using a cell voltage measurement line according to the present invention.
FIG. 3 is a cross-sectional view showing the main part of a voltage measuring unit using a cell voltage measuring line according to another embodiment of the present invention.
FIG. 4 is a front view showing an overall configuration of a fuel cell according to the present invention.
FIG. 5 is a perspective view showing a conventional voltage measurement state.
FIG. 6 is a perspective view showing a voltage measurement state of another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid polymer ion exchange thin film 2 Electrode 3 Thin film electrode assembly 4 Gas separator 4a Fuel gas flow path 4b Oxidant gas flow path 5 Single cell 6 Fuel cell stack 7 Slit 7a Recess 8 Cell voltage measurement line 8a Card type electric wire 8b Card Type wire 9 Elastic body 10 Concave stopper 11 Convex stopper

Claims (4)

A thin film electrode assembly 3 formed by sandwiching both sides of the solid polymer ion exchange thin film 1 with an electrode 2, and a fuel gas channel 4a and an oxidant gas channel 4b on both sides of the thin film electrode assembly 3 are sandwiched. The conductive gas separator 4 to be formed is provided, and the thin film electrode assembly 3 and the gas separator 4 sandwiched between the gas separators 4 constitute a single cell 5, and a plurality of the single cells 5 are stacked in series. In the solid polymer electrolyte fuel cell constituting the fuel cell stack 6,
A slit 7 formed in communication with the outside between the plurality of gas separators 4 superimposed, and a cell voltage measuring line 8 fitted to the slit 7 with the conductive surfaces facing outward from each other; A cell voltage measuring part structure of a solid polymer electrolyte fuel cell, wherein a voltage measuring line 8 is fitted into the slit 7 to measure the voltage of each single cell 5. Forming recesses 7a by mold molding on either the upper or lower surface continuous with the side surface of the gas separator 4;
The cell of the solid polymer electrolyte fuel cell according to claim 1, wherein the slit (7) is constituted by a recess (7a) of the gas separator (4) that appears on the side surface of the fuel cell stack (6) when the single cells (5) are stacked. Voltage measurement unit structure. The cell voltage measuring line 8 is composed of two card-type electric wires 8a and 8b having conductive surfaces facing outward, and an insulating elastic body 9 is sandwiched between the card-type electric wires 8a and 8b. The cell voltage measuring part structure of a solid polymer electrolyte fuel cell according to claim 1 or 2, wherein The elastic body 9 sandwiched between the two card-type electric wires 8a and 8b is formed so as to protrude from the tip or side end of the card-type electric wires 8a and 8b. A stopper 10 is provided, and a convex stopper 11 corresponding to the concave stopper 10 provided in the elastic body 9 is provided in the slit 7 of the gas separator 4, and the concave stopper 10 and the convex stopper 11 are fitted. The cell voltage measurement part structure of the solid polymer electrolyte fuel cell according to claim 3.

Images