JP2006351481A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect abnormal reaction inside a fuel cell. <P>SOLUTION: In a fuel cell system obtaining electromotive force from chemical reaction of reaction gas by supplying the reaction gas whose pressure is adjusted to prescribed pressure to each electrode of the fuel cell, a pressure measuring means measuring the pressure of the reaction gas in a gas passage is installed. The fuel cell system compares the pressure measured with the pressure measuring means with previously stored decision pressure, judges whether the measured pressure is larger than the decision pressure or not, and when decision is made that the measured pressure is larger than the decision pressure, the fuel cell system judges that the abnormal reaction occurs in the fuel cell. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system. More specifically, the present invention relates to a fuel cell system in which a reaction gas is supplied to an electrode of a fuel cell and an electromotive force is obtained from a chemical reaction of the reaction gas.

  Japanese Patent Application Laid-Open No. 9-147895 discloses a fuel cell system including a voltage sensor that measures the output voltage of the power generation unit of the fuel cell and a temperature sensor that detects the temperature of the power generation unit. In the fuel cell of this system, the fuel gas supplied to the anode-side electrode catalyst layer or the oxidant gas supplied to the cathode-side electrode catalyst layer cross leaks, causing abnormalities in the electrode catalyst layer and the solid polymer membrane. May cause combustion. In particular, since the catalyst in the electrode acts as a combustion catalyst, combustion is likely to occur at a relatively low temperature. For this reason, the conventional fuel cell system has a function of detecting the combustion state of the fuel cell.

  Specifically, first, the voltage sensor detects the voltage of the anode electrode and the voltage of the cathode electrode, and calculates the potential difference between them. When this potential difference is smaller than a predetermined reference value, it is determined that normal power generation is not performed. When the cause of power generation abnormality is due to abnormal combustion, it is considered that the temperature of the electrode is increased by the heat generated by the abnormal combustion. Therefore, in the conventional fuel cell system, when a power generation abnormality is detected, the temperature of the electrode is detected by a temperature sensor, and when the detected electrode temperature is higher than the reference temperature, abnormal combustion occurs in the fuel cell. Judge that When it is determined that abnormal combustion has occurred, the supply of the reaction gas to the fuel cell is stopped.

Japanese Patent Laid-Open No. 9-147895 JP 2003-45466 A

  In the conventional fuel cell system, an abnormality is predicted from the potential difference between the anode electrode and the cathode electrode, and then the presence or absence of abnormal combustion is determined from the electrode temperature. However, since heat easily diffuses, it is considered that the heat generated by abnormal combustion is diffused before being transmitted to the temperature sensor and may not be accurately transmitted. In particular, if the area that is in the combustion state and the position where the temperature sensor is located are somewhat distant from each other, it is considered that the combustion state may not be detected with sufficient sensitivity due to the large diffusion of heat until it is transmitted to the temperature sensor. It is done. However, it is not preferable to leave the combustion state in the fuel cell, and it is desirable to perform detection with sufficiently high sensitivity.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an improved fuel cell system so that an abnormal reaction in the fuel cell can be detected with high sensitivity.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a fuel cell system in which a reaction gas adjusted to a predetermined pressure is supplied to each electrode of a fuel cell and an electromotive force is obtained from a chemical reaction of the reaction gas.
Pressure measuring means for measuring the pressure in the gas flow path of the reaction gas;
A pressure determination unit that compares the measurement pressure measured by the pressure measurement unit with a determination pressure stored in advance to determine whether the measurement pressure is greater than a determination pressure;
Control means for determining that an abnormal reaction has occurred in the fuel cell when the measured pressure is determined to be greater than the determination pressure;
It is characterized by providing.

According to a second invention, in the first invention,
The fuel cell includes a plurality of stacked unit cells,
The gas flow path is
One gas supply pipe,
A plurality of branch pipes connected to the gas supply pipes and arranged to supply the reaction gas to the electrodes of the unit cells;
A plurality of branch pipes connected together, and one gas discharge pipe for discharging gas from the branch pipes,
The pressure measuring means is arranged in the gas supply pipe or the gas discharge pipe.

According to a third invention, in the first or second invention,
A pressure adjusting valve that is arranged in the gas flow path and automatically adjusts the pressure in the gas flow path to a predetermined pressure according to the opening degree;
Opening degree measuring means for measuring the opening degree of the pressure regulating valve;
An opening degree determining means for comparing the measured opening degree measured by the opening degree measuring means with a judgment opening degree stored in advance and determining whether the measured opening degree is larger than the judgment opening degree; ,
With
The control means includes
It is determined that an abnormal reaction has occurred only when the measured pressure is greater than the determination pressure and the measured opening is greater than the determined opening.

According to a fourth invention, in any one of the first to fourth inventions,
The fuel cell includes a plurality of stacked unit cells,
The fuel cell system includes:
Voltage measuring means for individually measuring the voltage generated by each unit cell;
A voltage determination unit that compares the measured voltage of each unit cell measured by the voltage measurement unit with a determination voltage stored in advance and determines whether or not each measurement voltage is smaller than the determination voltage; ,
A unit cell specifying means for specifying the unit cell determined that the measured voltage is smaller than the determination voltage as an abnormal unit cell in which an abnormal reaction has occurred;
It is characterized by providing.

A fifth invention is the fourth invention,
Change rate calculating means for calculating the rate of change of the measured pressure;
An abnormality occurrence area specifying means for specifying an abnormality occurrence area in the abnormality occurrence unit cell according to the rate of change and the measured voltage of the abnormality occurrence unit cell;
It is characterized by providing.

A sixth invention is any one of the first to fifth inventions,
The gas flow path is a cathode gas flow path.

In a seventh aspect based on any one of the first to sixth aspects,
The control means stops power generation of the fuel cell system when it is determined that an abnormal reaction has occurred.

  According to the first invention, the fuel cell system has pressure measuring means for measuring the pressure in the gas flow path of the reaction gas of the fuel cell, and detects an abnormal reaction in the gas flow path by the change in the measured pressure. To do. Here, it is also conceivable to detect an abnormal reaction with a temperature sensor. However, the heat generated by the abnormal reaction is diffused to the constituent members of the fuel cell and further released to the outside of the fuel cell. Therefore, it is difficult to reliably transmit the temperature increase due to the abnormal reaction to the temperature sensor. For this reason, variations in detection of an abnormal reaction due to temperature are likely to vary. In particular, when the abnormal reaction area and the position where the temperature sensor is arranged are separated, it is difficult to detect the abnormal reaction. In contrast, since the gas flow path of the reaction gas of the fuel cell is a closed space, a change in pressure caused by an abnormal reaction can be reliably transmitted to the pressure sensor. Even if the pressure measuring means is away from the area where the abnormal reaction has occurred, the pressure change is transmitted relatively accurately to the position where the pressure measuring means is disposed. Therefore, according to the first invention, it is possible to detect an abnormal reaction in the gas flow path with high sensitivity.

  According to the second invention, the pressure adjusting means of the fuel cell system is arranged in the gas supply pipe before the branch of the gas flow path or the gas discharge pipe after the assembly. The pressure change due to the abnormal reaction is reflected not only in the unit cell in which the abnormal reaction has occurred but also in the entire gas flow path. Therefore, the abnormal reaction of the entire fuel cell can be detected with only one pressure adjusting means.

  According to the third aspect of the invention, the presence or absence of an abnormal reaction is determined using the measured opening of the pressure adjustment valve that automatically adjusts the pressure in the gas flow path in addition to the pressure measured by the pressure measuring means. Therefore, even when there is an error in one of the measurement pressure and the measurement opening, it can be avoided that the presence or absence of an abnormal reaction is erroneously determined. Therefore, the abnormal reaction of the fuel cell can be detected more accurately.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for illustrating the configuration of a fuel cell system according to Embodiment 1 of the present invention.
As shown in FIG. 1, the fuel cell system includes a hydrogen tank 2. One end of a hydrogen supply pipe 4 is connected to the hydrogen tank 2. The hydrogen supply pipe 4 is provided with a pressure adjustment valve 6. The pressure adjustment valve 6 is a valve that automatically adjusts the pressure in the hydrogen supply pipe 4 to a predetermined pressure. The other end of the hydrogen supply pipe 4 is connected to the hydrogen inlet of the fuel cell 8. The fuel cell 8 is a solid polymer type battery.

  A hydrogen off gas discharge pipe 10 is disposed at the hydrogen off gas outlet of the fuel cell 8. An open / close valve 12 is provided in the hydrogen off-gas discharge pipe 10. The on-off valve 12 opens and closes the hydrogen off-gas discharge pipe 10. One end of a hydrogen circulation pipe 14 is arranged in the hydrogen off-gas discharge pipe 10 on the upstream side of the gas flow with respect to the on-off valve 12. The other end of the hydrogen circulation pipe 14 is connected to the hydrogen supply pipe 4.

  The fuel cell system includes a compressor 20. One end of an air supply pipe 22 is connected to the compressor 20. The other end of the air supply pipe 22 is connected to the air inlet of the fuel cell 8. One end of an air off gas discharge pipe 24 is connected to the air off gas outlet of the fuel cell 8.

  A pressure sensor 26 is disposed in the air off-gas discharge pipe 24 in the vicinity of the air off-gas outlet of the fuel cell 8. The pressure sensor 26 is a sensor that emits an output corresponding to the pressure in the air off-gas discharge pipe 24 near the air off-gas outlet (hereinafter referred to as “outlet pressure”). A pressure regulating valve 28 is disposed in the air off-gas discharge pipe 24 on the downstream side of the air off-gas flow with respect to the pressure sensor 26. The pressure adjustment valve 28 is a valve that adjusts the amount of air off-gas flowing out by changing the opening thereof, and thereby automatically adjusts the pressure in the air passage to a predetermined pressure.

  A voltmeter 30 is connected to the fuel cell 8. The voltmeter 30 can measure the output voltage of the fuel cell 8 for each cell. Further, the fuel cell system includes a control device 32. The control device 32 is connected to the hydrogen tank 2, the pressure adjustment valve 6, the on-off valve 12, the compressor 20, the pressure sensor 26, the pressure adjustment valve 28, and the voltmeter 30. The control device 32 receives outputs from the pressure sensor 26 and the voltmeter 30, calculates the outlet pressure and the voltage of each cell of the fuel cell 8, and supplies the reaction gas from the compressor 20 and the hydrogen tank 2 as necessary. The amount and the opening degree of the pressure regulating valves 6 and 28 are controlled.

FIG. 2 is a schematic diagram for explaining a case where combustion occurs in the oxygen gas flow path of the fuel cell 8 in the fuel cell system of the first embodiment.
A plurality of cells are stacked in the fuel cell 8 although not shown. In the cell, a cathode, an anode, and a solid polymer film sandwiched between both electrodes are disposed.

  As shown in FIG. 2, an oxygen gas flow path 34 is provided on the cathode side of each cell. Both ends of the oxygen gas passage 34 are connected to the air supply pipe 22 and the air off-gas discharge pipe 24 at the air inlet and the air off-gas outlet of the fuel cell, respectively. Air is supplied to the oxygen gas channel 34 as an oxidant gas for supplying oxygen to the cathode. In FIG. 2, only three oxygen gas flow paths 34 are schematically shown as straight pipes. However, actually, the oxygen gas flow path 34 is provided on the cathode side of all the cells, and each has a complicatedly meandering shape. In this fuel cell system, the air passage is branched from one air supply pipe 22 to the oxygen gas flow path 34 of each cell, and gathers again to be connected to one air off-gas discharge pipe 24. It is configured.

  On the other hand, similarly, a hydrogen gas flow path (not shown) is also provided on the anode side, and both ends of the hydrogen gas flow path are connected to the hydrogen supply pipe 4 and the hydrogen off gas discharge pipe 10 at the hydrogen inlet and the hydrogen off gas outlet, respectively. It is connected to the. Hydrogen is supplied as a fuel gas to the hydrogen gas flow path.

  During power generation of the fuel cell system, hydrogen is supplied from the hydrogen gas flow path to the anode side, and air is supplied from the oxygen gas flow path 34 to the cathode side. The hydrogen supplied to the anode becomes hydrogen ions as electrons are separated by the catalyst of the anode. Hydrogen ions move to the cathode side through the solid polymer membrane. At the cathode, hydrogen ions react with oxygen in the air to produce water. The electrons separated from the hydrogen ions travel to the cathode through another path. As a result, current flows from the cathode to the anode, and electric power is generated.

  During such a power generation reaction, hydrogen gas and air respectively supplied to the anode and cathode of the fuel cell 8 may leak through the solid polymer film. For example, as shown in FIG. 2, when the hydrogen gas channel leaks to the oxygen gas channel 34, the leaked hydrogen 36 may react with oxygen on the catalyst in the oxygen gas channel 34 to cause combustion.

FIG. 3 is a graph showing a change in outlet pressure when combustion occurs in the oxygen gas flow path 34.
When combustion occurs in the oxygen gas flow path 34, the air expands due to heat generated by the combustion and the pressure rises. Since the oxygen gas flow path 34 is a closed space, the pressure change due to expansion is reliably transmitted to the position of the pressure sensor 26. Therefore, as shown in FIG. 3, the outlet pressure starts to rise sharply immediately after time T ₁ when combustion occurs.

When the outlet pressure rises, the pressure adjustment valve 28 opens its opening greatly in order to adjust the pressure to a constant level. After the pressure regulating valve 28 is opened, the outlet pressure returns to normal pressure. Thereafter, the combustion of the reaction is completed at time T _2, the opening degree of the pressure regulating valve 28 returns to the normal opening.

  The control device 32 stores, as a “determination pressure”, an increase value of the outlet pressure that serves as a reference for determining that combustion of a scale that needs to be detected has occurred. This pressure is determined from the volume of the entire stack of fuel cells and the combustion volume of the scale that needs to be detected. The control device determines the presence or absence of combustion based on whether or not the outlet pressure exceeds the determination pressure. When it is determined that combustion is occurring in the fuel cell 8, the control device 32 stops the supply of fuel gas and oxidant gas from the compressor 20 and the hydrogen tank 2.

FIG. 4 is a flowchart for explaining a control routine performed by the control device 32 of the fuel cell system.
First, in step S102, the outlet pressure is measured (step S102). The control device 32 calculates the outlet pressure from the output of the pressure sensor 26 attached near the air off-gas outlet of the fuel cell 8. By measuring the outlet pressure, a change in pressure generated somewhere in the oxygen gas flow path 34 can be detected.

  Next, it is determined whether or not the measured outlet pressure is greater than the determination pressure (step S104). The control device 32 compares the determination pressure stored in advance with the outlet pressure to determine whether the outlet pressure is higher. Thereby, it is determined whether or not a pressure increase due to combustion in the fuel cell 8 occurs.

  If it is determined in step S104 that the outlet pressure is greater than the determination pressure, it is determined that combustion is occurring in the fuel cell 8, and the fuel cell system is stopped (step S106). That is, the control device 32 stops the supply of hydrogen gas and air to the fuel cell 8. If it is determined in step S104 that the outlet pressure is equal to or lower than the determination pressure, it is determined that the fuel cell system is operating normally, and this routine is temporarily terminated.

  As described above, in the first embodiment, the combustion state in the fuel cell 8 is detected from the outlet pressure. Since the oxygen gas flow path 34 to the fuel cell 8 is a closed space, the pressure increased by the combustion that has occurred in any of the cells is different from the temperature and is not discharged to the outside without being discharged outside. Until it is transmitted. Therefore, it is possible to detect the combustion state with high sensitivity by measuring the outlet pressure as compared with the case of using the temperature sensor. Therefore, abnormal combustion can be detected more reliably, and the abnormal combustion can be reliably avoided from developing into a trouble in the fuel cell system.

  In the first embodiment, the case where the pressure sensor 26 is arranged near the air off-gas outlet of the fuel cell 8 has been described. Thus, even when combustion is detected by the outlet pressure, it is possible to suppress variation in detection accuracy due to the position of the sensor. Therefore, for example, even when combustion occurs near the inlet of the fuel cell, the combustion state can be detected with high sensitivity. Moreover, since the air passage is a closed space, the pressure sensor 26 can detect a pressure change due to combustion with high sensitivity even if it is disposed at another position. Therefore, in the present invention, the position of the pressure sensor 26 is not limited to this position. For example, the pressure sensor 26 may be disposed on the air inlet side of the fuel cell 8. A plurality of pressure sensors 26 may be provided.

  Further, in the first embodiment, a case has been described in which it is determined that combustion is performed when the outlet pressure rises to the determination pressure, assuming that the pressure in the air passage is adjusted to be constant by the pressure adjustment valve 28. . This is based on the premise that abnormal combustion is determined in a normal operation state where the supplied gas pressure is constant to some extent. However, the present invention is not necessarily limited to this. For example, when the pressure in the air passage changes, an increased value that is increased with respect to the outlet pressure in the normal power generation state is calculated, and a judgment value (stored in advance corresponding to this increased value ( That is, the combustion may be determined based on a change amount allowable range).

  Moreover, in Embodiment 1, the case where the combustion in an air passage was detected was demonstrated. However, in the present invention, a combustion state generated on the hydrogen gas flow path side may be detected by arranging a pressure sensor on the hydrogen passage path side and detecting a pressure change.

Embodiment 2. FIG.
FIG. 5 is a diagram for explaining a change in the opening degree of the pressure adjustment valve 28 in the fuel cell system according to Embodiment 2 of the present invention.
The fuel cell system of the second embodiment has the same configuration as the fuel cell system described in the first embodiment. However, in the second embodiment, in addition to the output of the pressure sensor 26, the opening degree of the pressure adjustment valve 28 is also taken into consideration when determining whether or not the fuel cell 8 is in a combustion state.

When combustion occurs in the oxygen gas flow path 34 of the fuel cell 8, the outlet pressure changes as shown in FIG. When the outlet pressure rises, the pressure in the oxygen gas flow path 34 is returned to a predetermined pressure accordingly, so that the opening degree of the pressure adjustment valve 28 increases as shown in FIG. Pressure regulating valve 28 is opened after the combustion-generated time T _1, after the combustion end time T _2, after the expansion of air due to the combustion of the oxygen gas passage 34 has subsided, the flow returns to the normal opening.

  The control device 32 stores, as a “determination opening”, an opening that serves as a reference for determining that the opening of the valve has caused combustion of a scale that needs to be detected. In the second embodiment, the system determines that combustion has occurred only when the outlet pressure shown in FIG. 3 is equal to or higher than the determination pressure and when the valve opening is equal to or higher than the determination opening. To stop. Thereby, when a high pressure is detected due to malfunction of the pressure sensor 26 or the like, it can be prevented that it is erroneously determined that combustion has occurred.

FIG. 6 is a flowchart showing a control routine executed by the control device 32 of the fuel cell system in the second embodiment.
The control routine in the second embodiment is the same as the control routine of FIG. 4 except that steps S202 and S204 are executed between step S104 and step S106 of the routine shown in FIG.

  As shown in FIG. 6, when it is determined in step S104 that the outlet pressure is equal to or higher than the determination pressure, the opening degree of the pressure adjustment valve 28 is measured in step S202. The control device 32 calculates the opening degree from information related to the opening degree of the pressure regulating valve 28. Next, it is determined whether or not the measured opening of the pressure adjustment valve 28 is larger than the determination opening (step S204). That is, the control device 32 compares the determination opening stored in advance with the opening of the pressure adjustment valve 28 to determine whether the opening of the pressure adjustment valve 28 is larger than the determination opening. Thereby, it is determined whether or not the pressure in the oxygen gas flow path 34 has increased.

  If it is determined that the opening of the pressure adjustment valve 28 is larger than the determination opening, it is determined that combustion is occurring and the fuel cell system is stopped (step S106). On the other hand, if it is determined that the opening is equal to or less than the determination opening, it is determined that combustion has not occurred, and this routine is temporarily stopped. Therefore, even when it is determined that the outlet pressure is greater than the determination pressure, if the opening is not greater than the determination opening, it is determined that combustion has not occurred.

  As described above, in the second embodiment, both the outlet pressure and the opening degree of the pressure adjustment valve 28 are used for detecting the combustion of the fuel cell 8. Thereby, even when there is a malfunction of the pressure sensor 26 or the pressure adjustment valve 28, it is possible to avoid erroneously determining combustion. Therefore, it is possible to prevent the fuel cell system from being stopped unnecessarily due to a malfunction of the pressure sensor or the pressure adjustment valve 28.

  In the second embodiment, combustion is detected in consideration of both the outlet pressure and the opening degree of the pressure adjustment valve 28. However, the present invention is not limited to the combination of the opening degree of the pressure regulating valve 28 and the outlet pressure, which is used for judging combustion. For example, as in the first embodiment, the outlet pressure may be used alone as a determination material, or, using the opening characteristic of the pressure adjustment valve 28 in FIG. 5, step S102 in FIG. Without performing S104, the opening of the pressure regulating valve 28 may be used alone for combustion detection. Further, instead of measuring the outlet pressure, a temperature sensor may be disposed on the electrode, and a change in temperature and a change in the opening degree 28 of the pressure adjustment valve may be used as a judgment material for combustion.

Embodiment 3 FIG.
FIG. 7 is a schematic diagram for explaining the fuel cell 8 in the third embodiment.
The fuel cell system of Embodiment 3 has the same configuration as the fuel cell system of Embodiment 1.
FIG. 7 schematically shows each cell 38 in the stack of the fuel cell 8 and the oxygen gas flow path 34 in the cell 38. As shown in FIG. 7, the fuel cell 8 is configured by stacking a plurality of cells 38. Each of the plurality of cells 38 is provided with an oxygen gas flow path 34. The oxygen gas flow paths 34 are air passages branched from the air supply pipe 22, respectively. The voltage generated in each cell 38 can be individually measured by a voltmeter 30.

  In the cell 38a in which combustion has occurred, the generated voltage decreases. Therefore, the cell 38a whose voltage has dropped is identified as the combustion generation cell 38a. Further, when the voltage decrease width of the combustion generating cell 38a is large, that is, when the output voltage of the combustion generating cell 38a is small, it is expected that no gas is supplied into the combustion generating cell 38. Therefore, in this case, it can be predicted that a leak occurs in the upstream area A and combustion occurs in this area A. On the other hand, when the voltage decrease of the combustion generating cell 38a is small, that is, when the output voltage of the combusted cell 38 is relatively large, combustion occurs in the downstream area C of the cell 38a, and the upstream area A, The reaction gas is supplied to the central part B as usual, and the power generation reaction is expected to occur.

FIG. 8 is a graph showing a change in outlet pressure when combustion occurs in the upstream area A of the oxygen gas flow path 34 of a certain cell 38 a in the fuel cell 8. FIG. 9 is a graph showing changes in the outlet pressure when combustion occurs in the downstream area C of the fuel cell 8.
When combustion occurs in the upstream area A of the cell 38a, the leaked hydrogen reacts violently with oxygen, and the surrounding gas expands due to heat generation. However, the downstream volume is larger than the combustion area of the gas flow path. Therefore, since the influence of the expanded pressure is transmitted gently, as shown in FIG. 8, both the rise and fall of the change in the outlet pressure become gentle.

  On the other hand, when combustion occurs in the downstream area C of the cell 38a, the volume to the pressure sensor 26 is small. Therefore, the expansion of air due to combustion is immediately transmitted to the pressure sensor 26 and affects its output. Therefore, as shown in FIG. 9, the rise and fall of the change in the outlet pressure are abrupt. In any area where combustion occurs, the peak of the rise in the outlet pressure increases depending on the amount of combustion reaction.

  In the third embodiment, the combustion occurrence area is specified using the difference in pressure change and voltage change due to the difference in combustion area. Specifically, when the voltage decrease in the cell 38a is large, it is determined that combustion is occurring in the upstream area A. On the other hand, if the cell voltage drop is small and the outlet pressure changes rapidly, it is determined that combustion occurs in the downstream area C. In other cases, it is determined that the combustion is near the center.

  The control device 32 stores, as the “first determination voltage”, a reference value of the voltage generated by the cell 38 in specifying the combustion generating cell 38a. Further, in specifying the area, a reference voltage that can be determined to have a voltage drop with a large width to the extent that it can be determined that combustion is occurring in the upstream area A is stored as the “second determination voltage”. The second determination voltage is a voltage smaller than the first determination voltage. Further, the ratio of the pressure change that is a reference for determining that the pressure has suddenly changed to such an extent that it can be determined that the combustion is occurring in the downstream area C is stored as the “determination change rate”.

FIG. 10 is a flowchart for illustrating a routine performed by the control device 32 of the fuel cell system in the third embodiment of the present invention.
The control routine shown in FIG. 10 determines that the pressure is greater than or equal to the determination pressure in step S104 of FIG. 3, or the valve opening is determined to be greater than or equal to the determination opening in step S204 of FIG. It is executed after that.

  Specifically, when it is determined in step S104 or step S204 that combustion has occurred, first, the output voltage of each cell 38 of the fuel cell 8 is measured (step S302). The control device 32 individually measures the voltage generated by each cell 38 by calculating the voltage of each cell 38 from the output of the voltmeter 30. Next, the combustion generation cell 38a is specified (step S304). The control device 32 determines, for each cell 38, whether or not the measured voltage is lower than the first determination voltage, and combustion occurs in the cell 38 whose output voltage is lower than the first determination voltage. The generated combustion generation cell 38a is specified.

  Next, it is determined whether or not the voltage of the combustion generating cell 38a is smaller than the second determination voltage (step S306). The control device 32 compares the second determination voltage smaller than the first determination voltage stored in advance with the voltage of the combustion generation cell 38a, and determines whether or not the voltage of the combustion generation cell 38a is lower than the second determination voltage. To do. Thereby, it is determined whether or not the voltage of the combustion generating cell 38a has greatly decreased to such an extent that it can be determined that combustion has occurred in the upstream area A. If it is determined in step S306 that the voltage of the combustion generating cell 38a is smaller than the second determination voltage, it is determined that this combustion has occurred in the upstream area A of the combustion generating cell 38a (step S308), and this routine is executed. finish.

  On the other hand, when it is determined that the voltage of the combustion generating cell 38a is equal to or higher than the second determination voltage, the rate of change of the outlet pressure is calculated (step S310). The control device 32 calculates the rate of change based on the outlet pressure data measured in step S102. Next, it is determined whether or not the change rate is larger than the determination change rate (step S312). The control device 32 compares the determination change rate stored in advance with the calculated change rate, and determines whether or not the change rate is larger than the determination change rate. Thereby, it is determined whether or not the change in the outlet pressure is so rapid that it can be determined that combustion has occurred in the downstream area C.

  If it is determined in step S312 that the rate of change is greater than the determined rate of change, it is determined that combustion has occurred in the downstream area C of the cell 38a (step S314), and this routine is terminated. On the other hand, when it is determined that the change rate is equal to or less than the determination change rate, it is determined that combustion has occurred in the central portion B of the combustion generation cell 38a (step S316), and this routine is terminated.

  As described above, according to the third embodiment, it is possible to specify a cell in which combustion occurs and further determine in which part of the combustion generation cell 38a combustion is occurring. With this information, treatment for combustion can be taken immediately. These pieces of information can be used for maintenance of the fuel cell 8, identification of the cause of combustion, and the like.

  In Embodiment 3, when the voltage is smaller than the second voltage, it is determined that combustion is in the upstream area A, and when the change rate is greater than the determination change rate, it is determined that combustion is in the downstream area C. In other cases, the case where it is determined that the combustion is in the central portion B has been described. However, in the present invention, the identification of the combustion location is not limited to this. For example, only one of the change rate and the voltage is used as a judgment material, and the combustion in either the upstream area or the downstream area is determined. It may be determined. The identification of the burning area is not limited to three or two, but may be performed by storing several determination reference values and dividing into three or more areas.

  Also, in the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., unless specifically stated or in principle clearly specified by the number, It is not limited to the number mentioned. Further, the structures described in the embodiments, steps in the method, and the like are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

  In the first to third embodiments, the fuel gas and the oxidant gas, that is, hydrogen and oxygen correspond to the “reaction gas” of the present invention, and the hydrogen supply pipe 4 and the air supply pipe 22 are “gas supply pipe”. The hydrogen gas flow path and the oxygen gas flow path 34 correspond to “branch pipes”, the hydrogen off gas discharge pipe 10 and the air off gas discharge pipe 24 correspond to “gas discharge pipes”, and the pressure adjustment valve 28 Applicable to pressure regulating valve,

  In the first to third embodiments, by executing step S102, the “pressure measuring means” of the present invention is realized, and by executing step S104, the “pressure determining means” is realized, and step S106 is executed. By doing so, the “control means” is realized. In the second embodiment, by executing steps S202 and S204, the “opening measuring means” and the “opening determining means” of the present invention are realized. Further, by executing step S302 in the third embodiment, a “voltage measuring unit” is realized, and by executing step S304, a “voltage determining unit” and a “single cell specifying unit” are realized. Further, by executing step S310, the “change rate calculating means” of the present invention is realized, and by executing steps S306 to S316, “area specifying means” is realized.

It is a schematic diagram for demonstrating the fuel cell system in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the fuel cell system in Embodiment 1 of this invention. In the fuel cell system of Embodiment 1 of this invention, it is a graph for demonstrating the change of the exit pressure when combustion occurs. In Embodiment 1 of this invention, it is a flowchart for demonstrating the routine of control which the control apparatus of a fuel cell system performs. In the fuel cell system of Embodiment 2 of this invention, it is a graph for demonstrating the opening degree of the pressure control valve when combustion arises. In Embodiment 2 of this invention, it is a flowchart for demonstrating the routine of control which the control apparatus of a fuel cell system performs. It is a schematic diagram for demonstrating the fuel cell system in Embodiment 3 of this invention. In the fuel cell system of Embodiment 3 of this invention, it is a graph showing the change of the exit pressure when combustion occurs near the entrance of the fuel cell. In the fuel cell system of Embodiment 3 of this invention, it is a graph showing the change of outlet pressure when combustion occurs near the outlet of the fuel cell. In Embodiment 3 of this invention, it is a flowchart for demonstrating the routine of control which the control apparatus of a fuel cell system performs.

Explanation of symbols

2 Hydrogen tank 4 Hydrogen supply pipe 6 Pressure adjustment valve 8 Fuel cell 10 Hydrogen off gas discharge pipe 12 Open / close valve 14 Hydrogen circulation pipe 20 Compressor 22 Air supply pipe 24 Air off gas discharge pipe 26 Pressure sensor 28 Pressure adjustment valve 30 Voltmeter 32 Control Apparatus 34 Oxygen gas flow path 36 Leak hydrogen 38 cell 38a Combustion generation cell

Claims (7)

In a fuel cell system for supplying an electromotive force from a chemical reaction of the reaction gas by supplying a reaction gas adjusted to a predetermined pressure to each electrode of the fuel cell,
Pressure measuring means for measuring the pressure in the gas flow path of the reaction gas;
A pressure determination unit that compares the measurement pressure measured by the pressure measurement unit with a determination pressure stored in advance to determine whether the measurement pressure is greater than a determination pressure;
Control means for determining that an abnormal reaction has occurred in the fuel cell when the measured pressure is determined to be greater than the determination pressure;
A fuel cell system comprising: The fuel cell includes a plurality of stacked unit cells,
The gas flow path is
One gas supply pipe,
A plurality of branch pipes connected to the gas supply pipes and arranged to supply the reaction gas to the electrodes of the unit cells;
A plurality of branch pipes connected together, and one gas discharge pipe for discharging gas from the branch pipes,
The fuel cell system according to claim 1, wherein the pressure measuring unit is disposed in the gas supply pipe or the gas discharge pipe. A pressure adjusting valve that is arranged in the gas flow path and automatically adjusts the pressure in the gas flow path to a predetermined pressure according to the opening degree;
Opening degree measuring means for measuring the opening degree of the pressure regulating valve;
An opening degree determining means for comparing the measured opening degree measured by the opening degree measuring means with a judgment opening degree stored in advance and determining whether the measured opening degree is larger than the judgment opening degree; ,
With
The control means includes
3. The fuel according to claim 1, wherein it is determined that an abnormal reaction occurs only when the measured pressure is greater than the determination pressure and the measured opening is greater than the determined opening. Battery system. The fuel cell includes a plurality of stacked unit cells,
The fuel cell system includes:
Voltage measuring means for individually measuring the voltage generated by each unit cell;
A voltage determination unit that compares the measured voltage of each unit cell measured by the voltage measurement unit with a determination voltage stored in advance and determines whether or not each measurement voltage is smaller than the determination voltage; ,
A unit cell specifying means for specifying the unit cell determined that the measured voltage is smaller than the determination voltage as an abnormal unit cell in which an abnormal reaction has occurred;
The fuel cell system according to any one of claims 1 to 3, further comprising: Change rate calculating means for calculating the rate of change of the measured pressure;
An abnormality occurrence area specifying means for specifying an abnormality occurrence area in the abnormality occurrence unit cell according to the rate of change and the measured voltage of the abnormality occurrence unit cell;
The fuel cell system according to claim 4, comprising:   The fuel cell system according to claim 1, wherein the gas flow path is a cathode gas flow path.   8. The fuel cell system according to claim 1, wherein the control unit stops power generation of the fuel cell system when it is determined that an abnormal reaction has occurred.

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