JP2006127947A - Seal structure of fuel cell, and fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent leakage of a fuel gas from a fuel cell without causing increase of a manufacturing cost. <P>SOLUTION: Outer peripheral brim parts of separators 7, 9 are made protruded outside from the outer peripheral brim part of a fixed polymer film 1, and an air flow passage 19 for seal in which air provided with a pressure to suppress leakage of the fuel gas flowing in the fuel gas flow passage 7a of the fuel cell to the outside flows is installed between mutually protruding sites of the respective separators 7, 9. One part of the air which is an oxidizer gas to be supplied to the air flow passage 9a of the fuel cell is flowed in the air flow passage 19 for the seal. The inner seal part 18 provided with inner seal materials 15, 17 is installed at the inside of the air flow passage 19 for the seal, and the outer seal part 26 provided with outer seal materials 23, 25 is installed at the outside of the air flow passage 19 for the seal, respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention comprises a solid polymer membrane having electrodes on both sides sandwiched between a pair of separators, a fuel gas between one electrode and the separator, and an oxidant gas between the other electrode and the separator The present invention relates to a fuel cell seal structure and a fuel cell device for generating electricity by supplying each of the above.

  As a seal structure for preventing leakage of fuel gas in a fuel cell, for example, in Patent Document 1 below, a groove is provided in a portion facing the solid polymer film on the outer peripheral side of the separator, and a liquid seal is installed in the groove. Patent Document 2 below describes a method in which a sealing material made of rubber or the like is set on both separators that sandwich the solid polymer film from both sides, and the solid polymer film is sandwiched between the sealing material. Various structures for preventing leakage of fuel gas from the fuel cell have been proposed.

In addition, as described in, for example, Patent Document 3 below, fuel gas is recovered by filling a coolant in a stack case storing a fuel cell and installing a gas-liquid separator in the coolant circulation circuit. A structure that suppresses fuel gas leakage by making the inside of the stack case equal to or slightly higher than the operating pressure has also been proposed.
JP 2001-319668 A JP 2002-42837 A JP 2002-134138 A

  However, in the structure that suppresses fuel gas leakage using a sealing material that is normally used, such as the sealing structure described in Patent Documents 1 and 2, the leakage of fuel gas used in the fuel cell is completely prevented. Therefore, it is generally difficult to store the fuel cell in the case and scavenging the inside of the case, so that the leaked fuel gas is discharged to the outside of the case below the flammability limit. Has been done.

  By the way, when such a fuel cell is mounted on an automobile, the fuel cell is often arranged under the vehicle floor. For this reason, (1) there is no ingress of water in the case against water splashing or submersion, (2) fuel gas leaked into the case does not enter the vehicle compartment, (3) dust or There must be no dust ingress.

  However, in the stack case ventilation system that is generally adopted, the intake and exhaust ducts connected to the case need to be pulled to a position where there is no submergence and fuel gas does not enter the vehicle interior. In order to prevent dust, it is necessary to install a filter in the middle of the intake / exhaust duct. For this reason, there is a problem that the number of parts, vehicle weight, and manufacturing man-hours increase and the manufacturing cost increases. In addition, if the ventilator that ventilates the inside of the case breaks down, the fuel gas cannot be exhausted, and the space efficiency deteriorates due to an increase in parts.

  On the other hand, the device described in Patent Document 3 has a large-scale structure in which the fuel cell is accommodated in a stack case filled with a coolant, and the manufacturing cost is increased as described above.

  Accordingly, an object of the present invention is to reliably prevent leakage of fuel gas from a fuel cell without causing an increase in manufacturing cost.

  The present invention comprises a solid polymer membrane having electrodes on both sides sandwiched between a pair of separators, a fuel gas between the one electrode and the separator, and a fuel gas between the other electrode and the separator. In the fuel cell for supplying power by supplying each of the oxidant gas, the outer peripheral side edge of the separator protrudes outward from the outer peripheral side edge of the solid polymer membrane, and between the protruding portions of the separators, The most important feature is that a fuel gas capturing channel through which a gas for suppressing leakage of the fuel gas to the outside flows is provided.

  According to the present invention, the fuel gas capturing channel through which the gas for suppressing leakage of the fuel gas flows is provided between the protruding portions of the separator that protrudes outward from the outer peripheral edge of the fixed polymer membrane. Therefore, leakage of the internal fuel gas to the outside can be reliably suppressed by the gas flowing through the fuel gas capturing channel. In this case, the fuel gas capturing flow path is formed between the separators, and the structure is simple. The increase in the number of parts and the assembly are easy, and the increase in the manufacturing cost can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a part of a fuel cell according to an embodiment of the present invention. In this fuel cell, an anode electrode 3 is disposed on one side of the fixed polymer membrane 1, a cathode electrode 5 is disposed on the other side, and an anode-side separator 7 and a cathode-side separator 9 are respectively disposed on the outer sides thereof. . That is, this fuel cell is constructed by sandwiching a solid polymer membrane 1 having electrodes 3 and 5 on both sides between a pair of separators 7 and 9.

  Here, the fixed polymer membrane 1 has an outer peripheral edge protruding outward from the anode and cathode electrodes 3 and 5, and the separators 7 and 9 are arranged on the outer peripheral side of the fixed polymer membrane 1. The edge protrudes further outward.

  A fuel gas flow path 7a for flowing hydrogen as a fuel gas is formed in the anode-side separator 7 at a position facing the above-described anode electrode 3, and an oxidant gas is placed in the cathode-side separator 9 at a position facing the cathode electrode 5. As a result, an oxidant gas flow path 9a for flowing air is formed.

  Inner seal carriers 11 and 13 made of, for example, PET (polyethylene terephthalate) are provided on both sides of the protruding portion 1a protruding outward from the electrodes 3 and 5 of the fixed polymer film 1, and the separators of the inner seal carriers 11 and 13 are provided. Inner seals 15 and 17 made of, for example, silicon rubber are provided integrally on the 7 and 9 sides. The inner seal grooves 7b and 9b are formed in the separators 7 and 9 corresponding to the inner seal materials 15 and 17, respectively.

  The seal portion including the inner seal carriers 11 and 13 and the inner seal materials 15 and 17 is referred to as an inner seal portion 18.

  Air flow channel grooves 7c and 9c are provided on the surfaces of the separators 7 and 9 facing each other at the protruding portion protruding outward from the outer peripheral edge of the fixed polymer membrane 1, and these air flow channel grooves 7c and 9c are provided. The space formed between them is defined as a sealing air flow path 19 that serves as a fuel gas capturing flow path through which air, which is a gas having a pressure that suppresses leakage of the fuel gas to the outside, flows.

  Further, an outer seal carrier 21 made of, for example, PET is provided between the separators 7 and 9 outside the sealing air flow path 19, and silicon rubber is provided on the separator 7, 9 side of the outer seal carrier 21, for example. The outer sealing materials 23 and 25 made of are integrally provided. Then, outer seal grooves 7d, 9d are formed in the separators 7, 9 corresponding to the inner seal materials 23, 25, respectively.

  The seal portion provided with the outer seal carrier 21 and the outer seal materials 23 and 25 is referred to as an outer seal portion 26.

  Therefore, the seal portions 18 and 26 are provided between the separators 7 and 9 on both sides of the sealing air flow path 19, respectively.

  The inner and outer seal carriers 11, 13 and 21 described above serve as a so-called spacer that keeps the distance between the separators 7 and 9, and are crushed against the anode and cathode electrodes 3 and 5, which are gas diffusion electrodes. It also serves to properly manage the cost and to seal the fuel and air together with the inner and outer sealing materials 15, 17 and 23, 25. Further, the inner seal carriers 11 and 13 also serve to maintain the shape of the solid polymer film 1.

  The inner and outer sealing materials 15, 17, 23, and 25 described above may be bonded to the inner and outer seal carriers 11, 13, and 21, or a normal O-ring or liquid gasket may be used. Good.

  FIG. 2 is a plan view of the anode separator 7 as viewed from the side provided with the fuel gas flow path 7a. The anode-side separator 7 has a fuel gas inlet manifold through-hole 7e at the left end of the upper side of the fuel gas flow path 7a in FIG. 2, and a right end of the lower side of the fuel gas flow path 7a in FIG. The through holes 7f for the fuel gas outlet manifold are respectively formed.

  Each of the fuel gas inlet manifold and the fuel gas outlet manifold penetrates the entire fuel cell shown in FIG. 1 in the left-right direction in FIG. 1, and the fuel gas supplied from the outside of the fuel cell to the fuel gas inlet manifold is 2 is supplied to the fuel gas flow path 7a from the through hole 7e in FIG. 2 and used for power generation. Thereafter, the surplus flows out to the through hole 7f and is discharged from the fuel gas outlet manifold to the outside of the fuel cell.

  Further, the through hole 7g for the oxidant gas inlet manifold is formed at the lower part of the right side in FIG. 2 of the fuel gas flow path 7a, and the oxidant gas outlet at the upper part of the left side part in FIG. 2 of the fuel gas flow path 7a. A through hole 7h for the manifold is formed respectively. Air supplied to the oxidant gas inlet manifold from the outside of the fuel cell is supplied to the oxidant gas flow path 9a shown in FIG. 1 from the through hole 7g in FIG. 2 and used for power generation, and then the surplus is passed through the through hole 7h. To the outside of the fuel cell from the oxidant gas outlet manifold.

  Further, a through hole 7i for a cooling water inlet manifold is provided at the left end of the lower side of the fuel gas flow path 7a in FIG. 2, and a cooling water outlet is provided at the right end of the upper side of the fuel gas flow path 7a in FIG. A manifold through-hole 7j is formed.

  The cooling water supplied to the cooling water inlet manifold from the outside of the fuel cell is supplied from a through hole 7i in FIG. 2 to a cooling water flow path (not shown) formed on the surface opposite to the fuel gas flow path 7a of the anode side separator 7, for example. The fuel cell is then cooled, and then flows out into the through hole 7j and is discharged from the cooling water outlet manifold to the outside of the fuel cell.

  Here, the inner seal groove 7b surrounds the periphery of the fuel gas flow path 7a including the through holes 7e and 7f through which the fuel gas flows, and the through holes 7g and 7h through which the air flows and the through holes through which the cooling water flows. The holes 7i and 7j are formed so as to surround them.

  The air passage groove 7c located outside the inner seal groove 7b communicates with the through holes 7g and 7h through which air as an oxidant gas flows. In other words, a part of the air used for power generation of the fuel cell flows through the sealing air flow path 19 shown in FIG.

  The outer seal groove 7d is formed outside the air flow channel groove 7c so as to surround the outside of the through holes 7g and 7h through which air flows.

  The round holes 7k formed at the four corners of the anode-side separator 7 are holes for inserting, for example, fastening bolts for fixing the constituent members of the fuel cell.

  The anode side separator 7 is formed as described above, but the cathode side separator 9 is basically the same as the anode side separator 7. However, the cathode-side separator 9 is different from the anode-side separator 7 in that the through holes 7g and 7h through which air flows are communicated with the oxidant gas flow path 9a shown in FIG.

  Here, during operation of the fuel cell, the pressure of the air flowing through the sealing air passage 19 is set to be approximately equal to or higher than the pressure of the fuel gas flowing through the fuel gas passage 7a.

  At this time, each reaction gas (fuel gas and oxidant gas) is normally sealed by the inner seal portion 18. Then, when a minute defect or distortion occurs in the inner seal portion 18 and the fuel gas is about to leak to the outside, the pressure of the air flowing through the seal air flow path 19 is shown in FIG. By P, the fuel gas which is going to leak from the inner seal portion 18 is suppressed in the direction indicated by the arrow A, and as a result, the fuel gas is suppressed from leaking and can be prevented from flowing out to the outside.

  Further, as shown in FIG. 4, a defective portion 27 such as the inner seal member 15 is broken, and the fuel gas G flowing through the fuel gas flow path 7 a leaks from the defective portion 27 as indicated by an arrow B, Even if it enters the sealing air flow path 19 as in C, the leaked fuel gas does not leak outside the fuel cell because the outer seal portion 26 is on the outside.

  Furthermore, the air A flowing through the sealing air flow path 19 between the outer seal portion 26 and the inner seal portion 18 is a part of the air that always flows from the oxidant gas inlet manifold toward the outlet manifold during the fuel cell operation. Therefore, the leaked fuel gas indicated by the arrow C is discharged to the outside of the fuel cell in a state diluted with the air A flowing in the sealing air flow path 19.

  The fuel gas discharged together with the air A flowing through the sealing air flow path 19 is collected together with the exhaust after reaction, for example, by sending it to a combustor (not shown) and releasing it into the atmosphere after combustion. For this reason, it is possible to prevent the fuel gas leaked from the inner seal portion 18 from leaking out of the fuel cell as it is.

  In the seal structure according to the present embodiment, a sealing air flow path 19 may be formed between the separators 7 and 9, and an oxidant gas supplied to the fuel cell as air flowing through the sealing air flow path 19. Because a part of the air is used, a dedicated air supply device is not required, and the structure is simple, the increase in the number of parts is suppressed, and the assembly is easy. Can be suppressed.

  In the above-described embodiment, the air flowing through the sealing air flow path 19 is part of the air that is the oxidant gas supplied to the fuel cell, but the oxidant gas before being humidified before being supplied to the fuel cell. Alternatively, a dedicated air supply system may be used.

  In FIG. 5, a fuel cell stack 29 configured by laminating a large number of single fuel cells having the above-described seal structure is accommodated in a case 31 having a sealed structure.

  In FIG. 5, the hydrogen in the hydrogen tank 33 passes through the hydrogen supply pipe 35, is supplied to the fuel cell stack 29 via the hydrogen circulation device 37, and surplus hydrogen discharged from the fuel cell stack 29 is supplied to the hydrogen circulation pipe 39. After returning to the hydrogen circulation device 37, the fuel cell stack 29 is supplied again.

  On the other hand, air introduced through the air cleaner 43 by the compressor 41 flows through the air supply pipe 45 and is supplied to the fuel cell stack 29, and exhaust gas discharged from the fuel cell stack 29 passes through the exhaust pipe 47 in the combustor 49. Used for combustion of leaked hydrogen contained in exhaust.

  Further, a drain pipe 53 having a drain valve 51 is connected to the lower portion of the case 31, and water accumulated in the case 31 is discharged by opening the drain valve 51. On the other hand, an exhaust duct 57 having an exhaust valve 55 is connected to the upper portion of the case 31, and after stopping the fuel cell stack 29 during operation, the exhaust valve 55 is opened to release the internal pressure.

  The drain valve 51 described above is opened only for a short time as appropriate, considering that water accumulates inside the case 31. The exhaust valve 55 is normally closed during operation of the fuel cell stack 29, and after the operation of the fuel cell stack 29 is stopped, the stack 31 has a hydrogen concentration in the case 31 to prevent damage to the stack due to a pressure difference between the inside and outside of the fuel cell stack 29. A structure that opens in conjunction with other fail-safe functions when an unexpected situation such as exceeding the flammability limit occurs.

  During normal operation, the fuel cell stack 29 accommodated in the case 31 has the seal structure shown in FIG. 1 so that the fuel gas is extremely difficult to leak to the outside of the stack, and therefore the inside of the case 31 is ventilated. There is no need. Therefore, the exhaust valve 55 may remain closed. By doing so, it is possible to prevent water / dust / dust from entering the case 31.

  FIG. 6 shows that a failure occurs in the seal structure as shown in FIG. 4 from the normal state of FIG. This shows the case where air and fuel gas leaked to the extent that the safe function does not work.

  In this case, the inside of the case 31 starts to be filled with air leaking from the fuel cell stack 29 and fuel gas diluted with air. At this time, when the pressure P1 in the case 31 becomes equal to the fuel / air pressure P2 in the fuel cell stack 29, gas leakage from the fuel cell stack 29 into the case 31 can be suppressed. Also here, since the exhaust valve 55 is in the closed state, water / dust / dust does not enter the case 31.

  FIG. 7 shows a state when the operation of the fuel cell stack 29 is stopped. At this time, the exhaust valve 55 is opened to release the pressure in the case 31, and the pressure in the fuel cell stack 29 and the pressure in the case 31 after the stop are lowered, and the diluted fuel gas in the case 31 is supplied to the case 31. Release to the outside.

  FIG. 8 is a comparative example with respect to the examples shown in FIGS. Here, the inside of the case 310 that accommodates the fuel cell stack 290 is always ventilated by the ventilation fan 103 provided in the ventilation introduction duct 101 so that fuel gas does not accumulate. A ventilation air filter 105 is provided at the end of the ventilation introduction duct 101 on the ventilation introduction side.

  The case 310 is provided with an H2 sensor 107, and when the H2 sensor 107 detects a hydrogen concentration exceeding a set value (usually below the flammability limit), the entire system including the fuel cell stack 290 is urgently stopped. Other than this, except that the ventilation exhaust duct 109 is provided in the upper part of the case 310, it is the same as the configuration of FIG. 5 described above, and the same parts as those in FIG.

  In the case of the comparative example shown in FIG. 8, the ventilation fan 103 is always turned so that hydrogen does not stay in the case 31 during operation of the fuel cell stack 29. Here, for example, the ventilation fan 103 stops due to a failure or the like, the ventilation introduction duct 101 or the ventilation discharge duct 109 cannot be ventilated due to clogging or detachment, or the like. The failure of the fuel cell stack 290 due to the entry of dust or the like can be considered.

  On the other hand, in the structure according to the present invention shown in FIGS. 5 to 7, the ventilation introduction duct 101 and the ventilation fan 103 are unnecessary, and the exhaust duct 57 is always closed by the exhaust valve 55 during normal operation. Intrusion of water, dust, dust and the like into the case 31 can be prevented.

  According to the present invention, since the seal portions are provided between the separators on both sides of the fuel gas capturing channel, leakage of the fuel gas to the outside of the fuel cell can be more reliably suppressed.

  In addition, during operation of the fuel cell, the gas is always flowed through the fuel gas capturing channel, and these are collected and discharged by a predetermined method, so that the fuel gas does not leak to the outside of the fuel cell as it is. , And can be discharged outside the fuel cell in a state diluted with gas.

  Since the pressure of the gas flowing through the fuel gas capturing channel is made equal to or higher than the operating pressure of the fuel cell, the fuel gas can be reliably recovered and discharged.

  Since the fuel gas capturing channel is used by flowing air, the fuel gas can be discharged outside the fuel cell in a state diluted with air.

  Since the humidified air is used in the fuel gas capturing channel, the fuel gas can be discharged outside the fuel cell in a state diluted with the humidified air.

  Since a part of the oxidant gas supplied between the other electrode and the separator is caused to flow through the fuel gas capturing channel, a dedicated air supply device is unnecessary, which increases the manufacturing cost. Can be suppressed.

  Since the fuel gas capturing flow path is connected to the oxidant gas inlet and outlet manifolds, and simultaneously with the start of fuel cell operation, the oxidant gas is supplied to and discharged from the flow path. During the operation, leakage of fuel gas to the outside can always be suppressed.

  If the fuel cell having the above-described seal structure is accommodated in a case having a sealed structure, a malfunction may occur in the seal portion, and a slight fuel gas leak that does not activate the system fail-safe occurs. Since the leaked fuel gas flows into the case together with the air flowing through the air flow path and is diluted by the air, it is possible to prevent the fuel gas that is a combustible gas from being discharged to the outside of the fuel cell at a high concentration. At this time, when the pressure in the case becomes equal to the gas pressure in the fuel cell, the progress of gas leakage from the fuel cell can be prevented. In addition, by using a case with a sealed structure, entry of foreign matter such as water, dust, and dust into the case can be prevented, and the operating environment of the fuel cell can be improved.

It is sectional drawing which shows a part of fuel cell concerning one Embodiment of this invention. It is the top view seen from the side provided with the fuel gas flow path of the anode side separator in the fuel cell of FIG. It is operation | movement explanatory drawing by the seal structure of FIG. It is operation | movement explanatory drawing when a defect part generate | occur | produces in the inner seal material by the seal structure of FIG. FIG. 2 is an overall system configuration diagram showing a state in which a fuel cell stack configured by stacking a large number of fuel cell units each having the seal structure of FIG. 1 is housed in a case of a sealed structure. FIG. 6 is an operation explanatory diagram when a failure occurs in the seal structure as shown in FIG. 4 from the normal state of FIG. 5. It is operation | movement explanatory drawing which shows a state when the driving | operation of the fuel cell stack in FIG. 5 is stopped. It is operation | movement explanatory drawing which shows the comparative example with respect to the example shown to FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid polymer film 3 Anode side electrode 5 Cathode side electrode 7 Anode side separator 9 Cathode side separator 18 Inner seal part (seal part)
19 Sealing air flow path (fuel gas capture flow path)
26 Outer seal part (seal part)
31 Sealed case

Claims (9)

  A solid polymer membrane having electrodes on both sides is sandwiched between a pair of separators, a fuel gas is provided between the one electrode and the separator, and an oxidant gas is provided between the other electrode and the separator. In the fuel cell for supplying and generating electric power, the outer peripheral edge of the separator protrudes outward from the outer peripheral edge of the solid polymer membrane, and the outer portion of the fuel gas is disposed between the protruding portions of the separators. A fuel cell sealing structure, characterized in that a fuel gas capturing channel through which a gas that suppresses leakage is provided.   2. The fuel cell seal structure according to claim 1, wherein a seal portion is provided between the separators on both sides of the fuel gas capturing channel.   3. The fuel cell seal structure according to claim 1, wherein during the operation of the fuel cell, gas is continuously supplied to the fuel gas capturing channel, and these are collected and discharged by a predetermined method.   The fuel cell seal structure according to claim 3, wherein the pressure of the gas flowing through the fuel gas capturing channel is equal to or higher than the operating pressure of the fuel cell.   5. The fuel cell seal structure according to claim 3, wherein air is allowed to flow through the fuel gas capturing channel.   6. The fuel cell seal structure according to claim 5, wherein humidified air is allowed to flow through the fuel gas capturing channel.   The fuel cell according to any one of claims 1 to 6, wherein a part of the oxidant gas supplied between the other electrode and the separator is caused to flow through the fuel gas capturing channel. Seal structure.   2. The fuel gas capturing channel is connected to an oxidant gas inlet and outlet manifold, and the oxidant gas is supplied to the channel and discharged simultaneously with the start of fuel cell operation. The fuel cell seal structure according to claim 7.   9. A fuel cell device, wherein the fuel cell comprising the seal structure according to claim 1 is accommodated in a case having a sealed structure.

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