JP2006202545A - Fuel cell system and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system suppressing the generation of deterioration reaction of a fuel cell and suppressing decrease in durability of the fuel cell. <P>SOLUTION: The fuel cell system 100 is equipped with a polymer electrolyte membrane fuel cell 1, a fuel supply means, and control means S101-S123. A supply valve 63 opening and closing piping 53, a hydrogen supply pressure regulator 62 installed between a hydrogen main regulator 61 and a supply valve 63 and controlling the supply pressure of fuel gas, a first pressure sensor 72 for detecting supply pressure (first supply pressure P1) between the hydrogen main regulator 61 and the hydrogen supply pressure regulator 62, and a second pressure sensor 73 for detecting supply pressure (second supply pressure P2) between the supply valve 63 and a supply port 21a are installed in piping 52, 53. When a variation value per time (dP/dt) of the difference between the first supply pressure P1 and the second supply pressure P2 is larger than a prescribed value in the steady power generation of the fuel cell 1, the control devices S101-S123 determine that the supply valve 63 is closed, and sound an alarm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system.

  Patent Document 1 discloses a fuel cell system to which a conventional polymer electrolyte fuel cell (PEFC) is applied.

  In a fuel cell applied to this fuel cell system, a solid polymer membrane, which is an electrolyte membrane made of an ion exchange resin, is also referred to as a fuel electrode (also referred to as an anode electrode or a hydrogen electrode) and an air electrode (also referred to as a cathode electrode or an oxygen electrode). And a fuel chamber for supplying fuel gas to the fuel electrode.

  The fuel cell system includes a fuel supply unit and a pressure adjustment unit in addition to the fuel cell. The fuel supply means includes a supply path for supplying fuel gas with one end connected to the fuel cell, a supply valve for opening and closing the supply path, and a fuel supply source for supplying fuel gas connected to the other end of the supply path. is there. The pressure adjusting means is provided in the supply path downstream from the supply valve, and adjusts the supply pressure of the fuel gas supplied to the fuel cell. The supply path is provided with a pressure sensor that detects the supply pressure between the pressure adjusting means and the fuel cell.

  The fuel cell system also has a fuel discharge means for discharging exhaust fuel gas from the fuel chamber through the discharge path, and a circulation path connecting the discharge path and the supply path, and the exhaust fuel gas is connected to the supply path by the circulation path. And a fuel circulation means for supplying the fuel.

  The fuel discharge means opens and closes the discharge path with the exhaust valve to discharge the exhaust fuel gas from the fuel chamber. The fuel circulation means can re-supply exhaust fuel gas to the fuel chamber by opening and closing the circulation path with a fuel circulation valve.

  Furthermore, this fuel cell system has a control means for determining abnormality of the fuel discharge means based on a detection signal of the pressure sensor or the like during steady power generation of the fuel cell. For example, the control means determines an abnormality in which the discharge path cannot be opened or closed due to a failure of the exhaust valve of the fuel discharge means, and issues an alarm signal.

  The conventional fuel cell system having such a configuration operates as follows during steady power generation of the fuel cell in a state where the fuel cell can generate and transmit power. First, the fuel gas is supplied to the fuel chamber of the fuel cell through the supply path opened by the supply valve. At this time, the supply pressure of the fuel gas is adjusted by the pressure adjusting means. At the same time, air containing oxygen is also supplied to the air electrode of the fuel cell. As a result, an electromotive force is generated between the fuel electrode and the air electrode of the fuel cell. The exhaust fuel gas discharged from the fuel chamber is re-supplied to the fuel chamber again by the fuel circulation means, and the fuel gas is reused.

  In addition, the control means can detect the failure of the fuel discharge means during steady power generation of the fuel cell based on the detection signal of the pressure sensor that measures the supply pressure of the fuel gas between the pressure adjustment means and the fuel cell. Judge abnormalities and issue warnings.

  Thus, the conventional fuel cell system can supply electric power from the fuel cell, and recognizes an abnormality such as a failure in the fuel discharge means during steady power generation of the fuel cell. Then you can move on to the appropriate treatment.

JP 2003-92125 A

  However, since the fuel cell system of Patent Document 1 only determines an abnormality such as a failure of the fuel discharge means at the time of steady power generation of the fuel cell and issues an alarm. It is not possible to prevent the durability from being deteriorated due to a deterioration reaction in the fuel cell due to such a situation.

  That is, during steady power generation of the fuel cell, if the supply valve is closed due to some trouble such as disconnection of the signal cable, the supply of the fuel gas is completely stopped. For this reason, the fuel gas is not supplied to the fuel cell during steady power generation.

  When such a situation occurs, for example, it becomes impossible to supply the fuel gas into the fuel chamber that consumes the fuel gas, and a situation occurs in which the reaction distribution becomes uneven on the surface of the fuel electrode. For this reason, a local abnormal power generation state occurs in the fuel chamber, and performance deterioration such as a voltage drop of the entire fuel cell occurs (referred to as a flooding phenomenon). As a result, this fuel cell system causes a deterioration reaction in the fuel cell and impairs the durability of the fuel cell.

  The present invention has been made in view of the above-described conventional situation, and an object to be solved is to provide a fuel cell system that hardly causes a deterioration reaction in the fuel cell and does not easily impair the durability of the fuel cell.

A fuel cell system according to claim 1 is a fuel cell having a fuel chamber for sandwiching a solid polymer film between a fuel electrode and an air electrode and supplying fuel gas to the fuel electrode;
One end connected to the fuel cell, a supply path for supplying the fuel gas to the fuel chamber, a supply valve for opening and closing the supply path, and a fuel connected to the other end of the supply path for supplying the fuel gas Fuel supply means having a supply source;
A pressure adjusting means provided between the fuel supply source and the supply valve, for adjusting a supply pressure of the fuel gas supplied to the fuel cell;
First pressure detecting means for detecting a supply pressure between the fuel supply source and the pressure adjusting means;
Second pressure detecting means for detecting a supply pressure between the supply valve and the fuel cell;
If the change value per unit time of the difference in supply pressure detected by the first pressure detection means and the second pressure detection means is larger than a predetermined value during steady power generation of the fuel cell, the supply valve is closed. And a control means for issuing an alarm signal upon determining that the alarm has occurred.

  The fuel cell system of the present invention having such a configuration operates as follows during steady power generation of the fuel cell.

  First, the fuel gas whose supply pressure is adjusted by the pressure adjusting means is supplied to the fuel chamber of the fuel cell by the fuel supplying means. At the same time, air containing oxygen is also supplied to the air electrode of the fuel cell. As a result, an electromotive force is generated between the fuel electrode and the air electrode of the fuel cell. Further, as the fuel gas is consumed in the fuel chamber of the fuel cell, the fuel gas is supplied to the fuel chamber through the supply path. Thus, the fuel cell system of the present invention can supply power from the fuel cell during steady power generation of the fuel cell.

  Here, the supply path is provided with a supply valve, a pressure adjusting means, a first pressure detecting means, and a second pressure detecting means. The supply valve opens and closes the supply path, the pressure adjusting means adjusts the supply pressure of the fuel gas to a predetermined pressure, and the first pressure detecting means is a supply pressure (hereinafter referred to as a first pressure) between the fuel supply source and the pressure adjusting means. 1 supply pressure (P1)), and the second pressure detecting means detects a supply pressure between the supply valve and the fuel cell (hereinafter referred to as a second supply pressure (P2)).

  When the change value per unit time of the difference in supply pressure detected by the first pressure detection means and the second pressure detection means is larger than a predetermined value during steady power generation of the fuel cell, the control means It determines that the supply valve is closed and issues an alarm signal.

  That is, when the supply valve is normally open and the supply path is open during steady power generation of the fuel cell, the fuel path is consumed as fuel gas is consumed in the fuel chamber of the fuel cell. Fuel gas is supplied to the fuel chamber.

  At this time, for example, if the load connected to the fuel cell system varies, the output voltage of the fuel cell also varies. For this reason, the supply amount of the fuel gas also varies according to the variation in the output voltage of the fuel cell. Therefore, the first supply pressure (P1) and the second supply pressure (P2) also vary according to the variation in the fuel gas supply amount. On the other hand, if the load is constant at a predetermined magnitude, the supply amount of fuel gas is also constant at a predetermined flow rate, and the first supply pressure (P1) and the second supply pressure (P2) are also constant at a predetermined pressure. .

  For this reason, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) regardless of the variation in the magnitude of the load is When the supply valve is normally opened, the value is 0 or a value close thereto.

  On the other hand, in the case of steady power generation of the fuel cell, if there is an abnormality that the supply valve closes due to some trouble such as signal cable disconnection, the supply path is closed and the fuel gas supply is completely It will stop. For this reason, the fuel gas is not supplied to the fuel cell during steady power generation.

  At this time, the first supply pressure (P1) on the upstream side of the pressure adjusting means is maintained at a substantially constant pressure that is equal to or close to the supply pressure of the fuel gas from the upstream side because the flow rate of the fuel gas is eliminated. It will be. On the other hand, the second supply pressure (P2), which is downstream from the supply valve, starts to decrease immediately after the flow of the fuel gas is lost and the fuel gas is consumed in the fuel chamber of the fuel cell. Will be reduced.

  Therefore, in this fuel cell system, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) is determined by the supply valve. When an abnormality that closes occurs, the value is somewhat larger than zero.

  Therefore, in consideration of the above, the threshold value X set to be somewhat higher than 0 is compared with dP / dt, and when dP / dt ≦ X, the abnormality determination means determines that “at the time of steady power generation of the fuel cell” It can be determined that the supply valve is normally open. As a result, this fuel cell system continues the steady power generation of the fuel cell as it is.

  On the contrary, the threshold value X is compared with dP / dt, and when dP / dt> X, the control means determines that “the supply valve is closed at the time of steady power generation of the fuel cell” and immediately outputs an alarm signal. It emits.

  For this reason, if an alarm signal is issued during steady power generation of the fuel cell, the fuel gas cannot be supplied into the fuel chamber, and a local abnormal power generation state occurs in the fuel chamber. It becomes clear that a deterioration reaction occurs in the battery and the durability of the fuel cell is impaired. For this reason, the fuel cell system according to the present invention is suitable for appropriate measures such as an abnormal stop operation of the fuel cell in order to minimize or prevent such deterioration of the fuel cell and a decrease in durability. It can also be migrated.

  Therefore, the fuel cell system of the present invention is unlikely to cause a deterioration reaction in the fuel cell, and it is difficult to impair the durability of the fuel cell.

  3. The fuel cell system according to claim 2, wherein when the alarm signal is issued, the control means stops the fuel cell with a predetermined abnormal stop operation.

  In this case, since the fuel cell system can reliably bring the fuel cell into a power generation stop state, the safety of the fuel cell system can be further enhanced.

The present invention may also be a method for operating a fuel cell system. A fuel cell system operating method according to claim 3 includes a fuel cell having a fuel chamber for sandwiching a solid polymer film between a fuel electrode and an air electrode and supplying fuel gas to the fuel electrode;
One end connected to the fuel cell, a supply path for supplying the fuel gas to the fuel chamber, a supply valve for opening and closing the supply path, and a fuel supply for supplying fuel gas connected to the other end of the supply path A fuel supply means having a source;
In a method for operating a fuel cell system, comprising: a pressure adjusting unit that is provided between the fuel supply source and the supply valve and adjusts a supply pressure of the fuel gas supplied to the fuel cell.
During steady power generation of the fuel cell, a difference between a supply pressure between the fuel supply source and the pressure adjusting means and a supply pressure between the supply valve and the fuel cell is detected, and the unit time of the difference is detected. When the hit change value is larger than a predetermined value, it is determined that the supply valve is closed and an alarm signal is issued.

  Hereinafter, a first embodiment of the fuel cell system of the present invention will be described with reference to the drawings.

  A fuel cell system 100 of Example 1 shown in FIG. 1 is one in which the polymer electrolyte fuel cell 1 shown in FIG. 2 is applied.

  In the fuel cell 1, the laminate 10 is sandwiched between two end plates 20a and 20b via current collectors and insulating plates (not shown). As shown in FIG. 3, the stacked body 10 is formed by sequentially stacking MEA (Membrane Electrode Assembly) 11 while being sandwiched between separators 12. The MEA 11 includes an electrolyte membrane 11a made of an ion exchange resin, a fuel electrode 11b made of carbon integrally formed on one surface of the electrolyte membrane 11a, and an air electrode made of carbon integrally formed on the other surface of the electrolyte membrane 11a. 11c. All the fuel electrodes 11b are electrically connected to one current collector plate, and all the air electrodes 11c are electrically connected to the other current collector plate. As shown in FIG. Each terminal 1a, 1b protrudes from the fuel cell 1.

  As shown in FIG. 3, a fuel chamber 12a is formed on the fuel electrode 11b side of each separator 12, and hydrogen gas, which is a fuel gas, is supplied to the fuel electrode 11b by the fuel chamber 12a. On the other hand, an air chamber 12b is formed on the air electrode 11c side of each separator 12, and air containing oxygen is supplied to the air electrode 11c by the air chamber 12b. The fuel chamber 12a is opened in the horizontal direction, and the air chamber 12b is opened in the vertical direction, which is a direction orthogonal to the fuel chamber 12a. In addition, only the fuel chamber 12a or the air chamber 12b is formed in the separator 12 of the both ends of the laminated body 10. FIG. Thus, the single cell 10a of the fuel cell 1 is configured by the single MEA 11 and the pair of separators 12. As shown in FIG. 2, all the fuel chambers 12a of each cell 10a communicate with a supply port 21a formed in one end plate 20a and a discharge port 21b formed in the other end plate 20b.

  As shown in FIG. 1, the fuel cell 1 is assembled with other components to constitute a fuel cell system 100.

  The following various components are connected to the supply port 21a and the discharge port 21b provided in the fuel chamber 12a of the fuel cell 1 to supply hydrogen gas into the fuel chamber 12a or from the fuel chamber 12a. It is possible to discharge hydrogen gas or replace the inside of the fuel chamber 12a with outside air.

  A hydrogen tank 50 is provided at the most upstream side of the supply port 21a, and a pipe 51 is provided from the hydrogen tank 50 to the connection point A. The pipe 51 includes a hydrogen source solenoid valve 60, a hydrogen source pressure sensor 71, and a hydrogen source regulator 61 from the hydrogen tank 50 side.

  A pipe 52 is provided from the connection point A to the connection point B. The pipe 52 has a first pressure sensor 72 and a hydrogen supply pressure regulator 62 downstream thereof. The first pressure sensor 72 can detect the supply pressure (first supply pressure (P1)) of hydrogen gas between the hydrogen source regulator 61 and the hydrogen supply pressure regulator 62.

  A pipe 53 is provided from the connection point B to the connection point C. The pipe 53 has a supply valve 63 and a second pressure sensor 73 downstream thereof. The second pressure sensor 73 can detect the supply pressure of hydrogen gas (second supply pressure (P2)) between the supply valve 63 and the supply port 21a.

  A pipe 54 is provided from the connection point C to the supply port 21a. The pipe 54 has a relief valve 64 that is opened when the pressure in the pipe 54 rises excessively and releases the gas in the pipe 54 to the atmosphere.

  A pipe 56 is provided from the discharge port 21b to the connection point D. The pipe 56 has a hydrogen pump 81.

  A pipe 57 is provided from a connection point D on the downstream side of the hydrogen pump 81 to a duct 91 described later. The pipe 57 has a hydrogen exhaust electromagnetic valve 67.

  A pipe 58 is provided from the connection point D to the connection point C via the connection point E. The pipe 58 has a hydrogen circulation solenoid valve 68 between the connection point D and the connection point E.

  The connection point E is provided with a pipe 55 whose other end is open. The pipe 55 includes an outside air introduction electromagnetic valve 65 and a filter 55b attached to the open end.

  The hydrogen tank 50, the pipe 51, the hydrogen source solenoid valve 60, the hydrogen source pressure sensor 71, and the hydrogen source regulator 61 constitute a fuel supply source. The pipes 52, 53, and 54 are supply paths. The fuel supply source, the supply path, and the supply valve 63 constitute fuel supply means.

  The hydrogen supply pressure regulator 62 is a pressure adjusting means for adjusting the supply pressure of hydrogen gas to a predetermined pressure. The first pressure sensor 72 is first pressure detection means, and the second pressure sensor 73 is second pressure detection means.

  Furthermore, the pipes 56 and 57 are discharge paths. The pipes 56 and 57 as the discharge path, the hydrogen pump 81, and the hydrogen exhaust electromagnetic valve 67 constitute fuel discharge means for discharging exhaust hydrogen gas from the discharge port 21b via the discharge path.

  Pipes 56, 58, and 54 are circulation paths that connect the discharge port 21b and the supply port 21a. The piping 56, 58, 54 as the circulation path, the hydrogen pump 81, and the hydrogen circulation electromagnetic valve 69 constitute fuel circulation means for supplying exhaust hydrogen gas to the supply port 21a.

  Further, the pipes 55, 58 and 54 are outside air paths. The outside air replacement means for supplying outside air to the supply port 21a and substituting the inside of the fuel chamber 12a with air is constituted by the piping 55, 58, 54 as the outside air path, the filter 55b, and the outside air introducing electromagnetic valve 65. Yes.

  Further, an air manifold 42 for taking in air is provided above the fuel cell 1. An air intake fan 41 having a filter 41a is connected to the air manifold 42 so that air can be supplied into the air chamber 12b. The air manifold 42 is provided with a water injection nozzle 99. The water injection nozzle 99 is connected to a water tank 97 in which a level gauge 97 a is built by a pipe 98. The pipe 98 includes a filter 98 a and a water direct injection pump 83.

  Further, below the fuel cell 1, an air discharge path 90 having a temperature sensor 90a, a condenser 92, a condenser fan 93, and a duct 91 for guiding the discharged air from the air discharge path 90 to the condenser 92, Is provided so that air can be discharged from the air chamber 12b. The condenser 92 is capable of separating air and water. The condenser 92 includes a pipe 94 for discharging the separated air to the atmosphere, a filter 94a, and a temperature sensor 94b. A pipe 96 for transporting the water to the water tank 97 and a water recovery pump 82 are provided.

  The fuel supply means, the pressure adjustment means, the fuel discharge means, the fuel circulation means, the outside air replacement means, the first pressure sensor 72 and the second pressure sensor 73 are electrically connected to the control system 45 and can be controlled. . The air suction fan 41, the level gauge 97a, the water direct injection pump 83, the temperature sensor 90a, the condenser fan 93, and other components are also electrically connected to the control system 45 and can be controlled.

  Further, the control system 45 includes control means S101 to S123, the details of which will be described later with reference to FIG. The control means S101 to S123 are configured so that the difference (P1−P2) between the first supply pressure (P1) based on the detection value of the first pressure sensor 72 and the second supply pressure (P2) based on the detection value of the second pressure sensor 73. ) Is determined based on a change value per unit time (dP / dt), and an abnormality that causes the supply valve 63 to close during steady power generation of the fuel cell 1 is determined, and an alarm signal is issued. Further, the control means stops the fuel cell 1 with a predetermined abnormal stop operation when an alarm signal is given.

  An outline of the operation of the fuel cell system 100 having the above configuration will be described. In the fuel cell system 100, during steady power generation of the fuel cell 1, air is taken in by the air suction fan 41 and the air manifold 42, and air is supplied into the air chamber 12b as shown in FIG. Then, hydrogen gas is supplied from the hydrogen tank 50 to the fuel chamber 12a through the supply port 21a by the fuel supply means. Thereby, an electrochemical reaction can be caused between the air electrode 11c and the fuel electrode 11b, and an electromotive force can be obtained.

  During this time, as shown in FIG. 1, exhaust hydrogen gas is re-supplied from the discharge port 21 b to the supply port 21 a by the pipes 56, 58, 54, the hydrogen pump 81, and the hydrogen circulation electromagnetic valve 68, 57, a hydrogen pump 81, and a hydrogen exhaust solenoid valve 67, exhaust hydrogen gas and produced water are intermittently transferred from the discharge port 21b of the fuel chamber 12a to the condenser 92 via the duct 91, and electrochemically. While continuously causing the reaction, it is possible to suppress a decrease in performance due to excessive retention of water in the fuel chamber 12a.

  Further, the water in the water tank 97 is pumped by the water direct injection pump 83 and injected from the water injection nozzle 99 into the air manifold 42. Thereby, drying of the air electrode 11c is prevented and the fuel cell 1 is cooled. Further, the air containing water discharged from the air chamber 12 b of the fuel cell 1 is transferred from the air discharge path 90 to the condenser 92 through the duct 91. The air separated by the condenser 92 is discharged from the pipe 94 to the atmosphere, and the separated water is collected in the water tank 97 by the water collection pump 82. Similarly, the exhaust hydrogen gas and the generated water transferred to the condenser 92 via the duct 91 are separated into hydrogen and water, the hydrogen is discharged into the atmosphere together with the air, and the water is collected in the water tank 97. The

  In the fuel cell system 100 that operates in this way, as shown in FIG. 4, the control means S101 to S123, when the fuel cell 1 is in a steady state of power generation, the abnormality occurs that the supply valve 63 closes due to some trouble, In the following procedure, it is determined that “the supply valve 63 is closed during steady power generation of the fuel cell 1”, and an alarm signal is issued.

  First, the control means performs the abnormality determination process according to the program shown in FIG. 4 continuously or periodically at a relatively short interval during the steady operation of the fuel cell 1.

  When the program of FIG. 4 is executed, first, in steps S101 to S117, the first supply pressure (P1) based on the detection value of the first pressure sensor 72 and the second supply based on the detection value of the second pressure sensor 73 are performed. A change value (dP / dt) per unit time of the difference (P1−P2) from the pressure (P2) is compared with a threshold value X described later. In this program, m is the number of comparisons between dP / dt and X, and n is the number of times determined in succession as dP / dt> X. The reason for this is to eliminate noise and errors of the first pressure sensor 72 and the second pressure sensor 73.

  Here, the threshold value X is determined in consideration of fluctuations in the first supply pressure (P1) and the second supply pressure (P2) that are caused by fluctuations in the magnitude of the load connected to the fuel cell system 100.

  That is, when the supply valve 63 is normally open and the pipe 53 is open during steady power generation of the fuel cell 1, for example, if the load connected to the fuel cell system 100 varies. The output voltage of the fuel cell 1 also varies. For this reason, according to the fluctuation | variation of the output voltage of the fuel cell 1, the supply amount of hydrogen gas also fluctuates. For this reason, the first supply pressure (P1) on the upstream side of the hydrogen supply pressure regulator 62, which is a pressure adjusting means, and the second supply pressure, which is on the downstream side of the supply valve 63, according to fluctuations in the supply amount of hydrogen gas. (P2) also varies. On the other hand, if the load is constant at a predetermined magnitude, the supply amount of hydrogen gas is also constant at a predetermined flow rate, and the first supply pressure (P1) and the second supply pressure (P2) are also constant at a predetermined pressure. .

  For this reason, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) regardless of the variation in the magnitude of the load is When the supply valve 63 is normally opened, the value is 0 or a value close thereto.

  On the other hand, in the case of steady power generation of the fuel cell 1, if an abnormality occurs such that the supply valve 63 closes due to some trouble such as disconnection of the signal cable, the supply of hydrogen gas is completely stopped. For this reason, hydrogen gas is no longer supplied to the fuel cell 1 during steady power generation.

  At this time, the first supply pressure (P1) on the upstream side of the hydrogen supply pressure regulator 62 is equal to or close to the supply pressure of the hydrogen gas from the upstream hydrogen source regulator 61 because the flow rate of the hydrogen gas is eliminated. An almost constant pressure will be maintained. On the other hand, the second supply pressure (P2), which is downstream of the supply valve 63, immediately begins to decrease because the flow rate of hydrogen gas disappears and the hydrogen gas is consumed in the fuel chamber 12a of the fuel cell 1. After that, it will decrease continuously.

  Therefore, in this fuel cell system 100, the change value (dP / dt) per unit time of the difference (P1-P2) between the first supply pressure (P1) and the second supply pressure (P2) When an abnormality that closes 63 occurs, the value is somewhat larger than zero.

  Therefore, in consideration of the above, the threshold value X is set to a value that is somewhat higher than 0 to the extent that the fluctuation in dP / dt accompanying the fluctuation in the magnitude of the load connected to the fuel cell system 100 is not determined to be abnormal. It is preferable to do.

  Then, as described above, when the number m of comparisons between dP / dt and X reaches the specified number as a result of performing steps S101 to S117, the control means ends the abnormality determination process, and “fuel cell 1 It is determined that the supply valve 63 is normally open at the time of steady power generation. As a result, the fuel cell system 100 continues the steady power generation of the fuel cell 1 as it is.

  On the other hand, when the number of times n determined continuously as dP / dt> X has reached the number of times of abnormality determination, in step S119, the control means indicates that “the supply valve 63 is closed during steady power generation of the fuel cell 1”. judge. Then, in step S121, the control means issues an alarm signal that “the supply valve 63 is closed during steady power generation of the fuel cell 1”. As a result, the fuel cell system 100 recognizes the abnormality and proceeds to step S123. Then, the control means performs a predetermined abnormal stop operation such as switching the hydrogen source electromagnetic valve 60 from the open state to the closed state, or replacing the hydrogen gas in the fuel chamber 12a with outside air, and stops the power generation of the fuel cell 1. To make it happen.

  For this reason, the fuel cell system 100 can minimize or prevent the occurrence of a deterioration reaction in the fuel cell 1 due to the inability to supply hydrogen gas into the fuel chamber 12a.

  Therefore, the fuel cell system 100 is unlikely to cause a deterioration reaction in the fuel cell 1 and the durability of the fuel cell 1 is not easily impaired.

  Further, in the fuel cell system 100, when the control unit issues an alarm signal, the fuel cell 1 is immediately shifted to a predetermined abnormal stop operation, and the fuel cell 1 can be surely brought into a power generation stop state. Therefore, the safety of the fuel cell system 100 can be further enhanced.

  Here, in the fuel cell system 100 of Example 1, as described below, an evaluation test of an abnormality determination unit assuming a failure of the supply valve 63 was performed. In addition, noise removal processing is performed for all graphs showing the results of the following tests.

  As a basic test, first, at the time of steady power generation of the fuel cell 1, the first supply pressure (P1) and the second supply pressure (P2) that are generated as the load connected to the fuel cell 1 fluctuates. Measurements were performed for variation.

  Specifically, as shown in FIG. 5 (a), the output power of the fuel cell system 100 was changed stepwise, assuming a change in the magnitude of the load connected to the fuel cell 1. In FIG. 5 (a), G1 represents the time change of the output power of the fuel cell system 100.

  At this time, as shown in FIG. 5B, the first supply pressure (P1) was continuously detected by the first pressure sensor 72, and the second supply pressure (P2) was detected by the second pressure sensor 73. . In FIG. 5B, G2 represents a time change of the first supply pressure (P1), and G3 represents a time change of the second supply pressure (P2). In addition, the time axis of Fig.5 (a) and FIG.5 (b) is the same scale.

  As a result, the first supply pressure (P1) and the second supply pressure (P2) are also changed according to the change in the output voltage of the fuel cell 1. In addition, the tendency of fluctuations in the first supply pressure (P1) and the second supply pressure (P2) is almost the same. This is because the supply amount of hydrogen gas varies as the output voltage of the fuel cell 1 varies. Further, in a state where the output power of the fuel cell 1 is kept constant at each stage, the first supply pressure (P1) and the second supply pressure (P2) are also constant at a predetermined pressure. This is because if the output voltage of the fuel cell 1 is constant, the supply amount of hydrogen gas is also constant at a predetermined flow rate.

  Therefore, regardless of fluctuations in the output power of the fuel cell 1, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2). It can be seen that when the supply valve 63 is normally opened, the value becomes 0 or a value close thereto.

Next, as an evaluation test, a simulation test for the occurrence of abnormality in the supply valve 63 was performed. Specifically, as shown in FIG. 6, during steady power generation of the fuel cell 1, the output power of the fuel cell 1 is kept constant, and the supply valve 63 is controlled by the control means at time (T ₀ ). By switching from the open state to the closed state, an abnormality that the supply valve 63 closes was simulated. As a result, the pipe 53 constituting the supply path is closed, and hydrogen gas is no longer supplied into the fuel chamber 12a of the fuel cell 1. This point was regarded as the occurrence of abnormality in this evaluation test.

  At this time, the first supply pressure (P1) was continuously detected by the first pressure sensor 72, and the second supply pressure (P2) was detected by the second pressure sensor 73. In FIG. 6, G4 shows the time change of the first supply pressure (P1), G5 shows the time change of the second supply pressure (P2), and G6 shows the first supply pressure (P1) and the second supply pressure (P2). ) With respect to time (P1-P2).

As a result, when the supply valve 63 before the time (T ₀ ) is not switched from the open state to the closed state, the first supply pressure (P1), the second supply pressure (P2), and the first supply pressure ( The difference (P1−P2) between P1) and the second supply pressure (P2) is constant.

On the other hand, when the supply valve 63 is switched from the open state to the closed state at time (T ₀ ), the pipe 53 is closed, and hydrogen gas is not supplied into the fuel chamber 12 a of the fuel cell 1.

  At this time, the first supply pressure (P1) is maintained at a substantially constant pressure that is equal to or close to the supply pressure of the hydrogen gas from the upstream hydrogen source regulator 61 because the hydrogen gas does not flow.

On the other hand, the second supply pressure (P2) starts to decrease immediately after the hydrogen gas does not flow and the hydrogen gas is consumed in the fuel chamber 12a of the fuel cell 1, and then decreases continuously. . However, as can be seen from the results of the basic test described above, the second supply pressure (P2) fluctuates with fluctuations in the output power of the fuel cell 1 during steady power generation of the fuel cell 1, so the second supply pressure ( Even if the absolute value of P2) starts to decrease, it cannot be immediately judged as abnormal. In this evaluation test, it can be determined that there is an abnormality at the time (T ₁ ) when the absolute value of the second supply pressure (P2) is sufficiently reduced. For this reason, it is understood that the required time becomes longer when the abnormality determination is made based on the absolute value of the second supply pressure (P2).

  Further, the case where the abnormality is determined based on the absolute value of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) is the same as the above case.

  For the above abnormality determination method, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) is as follows. It can be quickly determined as abnormal.

That is, as indicated by G6 in FIG. 6, immediately after time (T ₀ ), the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) has a certain slope. Therefore, the change value (dP / dt) per unit time of the difference (P1−P2) between the first supply pressure (P1) and the second supply pressure (P2) is immediately after the time (T ₀ ). The value is somewhat larger than 0. For this reason, the threshold value X is set in consideration of the fluctuations of the first supply pressure (P1) and the second supply pressure (P2) in the basic test, and by comparing dP / dt and the threshold value X, the abnormality is promptly determined to be abnormal. It can be judged. Note that the unit time in dP / dt is preferably set appropriately so as not to pick up noise or the like detected by sensors.

  Thus, from the results of the basic test and the evaluation test described above, it can be confirmed that the fuel cell system 100 of Example 1 can quickly determine that “the supply valve 63 is closed during steady power generation of the fuel cell 1”.

  In the above, the present invention has been described with reference to the first embodiment. However, the present invention is not limited to the first embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the spirit of the present invention. .

    The present invention is applicable to a fuel cell system.

1 is a schematic configuration diagram according to a fuel cell system of Example 1. FIG. 1 is an exploded perspective view of a fuel cell according to a fuel cell system of Example 1. FIG. 1 is a schematic cross-sectional view of a fuel cell stack according to a fuel cell system of Example 1. FIG. 3 is a flowchart of an abnormality determination processing program during steady power generation of the fuel cell according to the fuel cell system of Example 1; (A) And (b) is a graph which shows the result of a basic test regarding the fuel cell system of Example 1. FIG. 6 is a graph showing the results of an evaluation test relating to the fuel cell system of Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 11a ... Solid polymer membrane (electrolyte membrane)
11b ... Fuel electrode 11c ... Air electrode 12a ... Fuel chamber 12b ... Air chamber 50, 51, 60, 71, 72 ... Fuel supply source (50 ... Hydrogen tank, 51 ... Piping, 60 ... Hydrogen source solenoid valve, 61 ... Hydrogen source Regulator, 71 ... Hydrogen source pressure sensor)
52, 53, 54 ... Supply path (pipe)
50, 51, 52, 53, 54, 60, 61, 71, 63 ... fuel supply means (63 ... supply valve)
62 ... Pressure adjusting means (hydrogen supply pressure regulator)
72: First pressure detecting means (first pressure sensor)
73. Second pressure detecting means (second pressure sensor)
P1: Supply pressure between the fuel supply source and the pressure adjusting means (first supply pressure)
P2: Supply pressure between the supply valve and the fuel cell (second supply pressure)
dP / dt: change value per unit time of difference in supply pressure detected by the first pressure detection means and the second pressure detection means (dP = P1-P2)
DESCRIPTION OF SYMBOLS 100 ... Fuel cell system S101, S103, S105, S107, S109, S111, S113, S115, S117, S119, S121, S123 ... Control means

Claims (3)

A fuel cell having a fuel chamber for sandwiching a solid polymer film between a fuel electrode and an air electrode and supplying fuel gas to the fuel electrode;
One end connected to the fuel cell, a supply path for supplying the fuel gas to the fuel chamber, a supply valve for opening and closing the supply path, and a fuel connected to the other end of the supply path for supplying the fuel gas Fuel supply means having a supply source;
A pressure adjusting means provided between the fuel supply source and the supply valve, for adjusting a supply pressure of the fuel gas supplied to the fuel cell;
First pressure detecting means for detecting a supply pressure between the fuel supply source and the pressure adjusting means;
Second pressure detecting means for detecting a supply pressure between the supply valve and the fuel cell;
If the change value per unit time of the difference in supply pressure detected by the first pressure detection means and the second pressure detection means is larger than a predetermined value during steady power generation of the fuel cell, the supply valve is closed. A fuel cell system comprising: control means for determining that the alarm has occurred and issuing an alarm signal.   2. The fuel cell system according to claim 1, wherein the control means is configured to stop the fuel cell by a predetermined abnormal stop operation when the alarm signal is issued. A fuel cell having a fuel chamber for sandwiching a solid polymer film between a fuel electrode and an air electrode and supplying fuel gas to the fuel electrode;
One end connected to the fuel cell, a supply path for supplying the fuel gas to the fuel chamber, a supply valve for opening and closing the supply path, and a fuel supply for supplying fuel gas connected to the other end of the supply path A fuel supply means having a source;
In a method for operating a fuel cell system, comprising: a pressure adjusting unit that is provided between the fuel supply source and the supply valve and adjusts a supply pressure of the fuel gas supplied to the fuel cell.
During steady power generation of the fuel cell, a difference between a supply pressure between the fuel supply source and the pressure adjusting means and a supply pressure between the supply valve and the fuel cell is detected, and the unit time of the difference is detected. An operation method of a fuel cell system, characterized in that, when the hit change value is larger than a predetermined value, it is determined that the supply valve is closed and an alarm signal is issued.

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