JP4935038B2 - Fuel cell system and method for starting fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system for diluting and exhausting hydrogen accumulated by crossing over from an anode to a cathode while the fuel cell system is stopped, and a starting method thereof.

  In general, a fuel cell is a device that directly converts chemical energy of a fuel gas into electrical energy by electrochemically reacting a fuel gas such as hydrogen and an oxidant gas such as air. A polymer electrolyte fuel cell using a polymer electrolyte membrane as an electrolyte membrane is known.

  In this polymer electrolyte fuel cell system, hydrogen is usually left in the anode when the system is stopped. If the hydrogen remaining in the anode is left as it is, it crosses over from the anode to the cathode and accumulates in the cathode path. The accumulated high concentration hydrogen may be discharged from the cathode at a high concentration at the next start-up.

  As a method for solving such a problem, there is a fuel cell system that is configured to discharge until the output voltage becomes 0 V when stopped and consume residual hydrogen. For example, Japanese Patent Laid-Open No. 2001-345114 (Patent Document) 1).

  There is also a fuel cell system configured to suppress the flow rate of air exhausted at startup and reduce the amount of discharged hydrogen, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-172027 (Patent Document 2). Furthermore, in the conventional example disclosed in Patent Document 2, air is bypassed from the downstream side of the compressor to the exhaust path, and the hydrogen is diluted by the air.

Further, a conventional example of a fuel cell system configured to dilute hydrogen by providing a dilution device such as a dilution box and a dilution blower is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-179102 (Patent Document 3).
JP 2001-345114 A JP 2004-172027 A JP 2004-179102 A

  In the conventional example disclosed in Patent Document 1 described above, the remaining hydrogen is consumed by discharging until the output voltage reaches 0 V when the system is stopped. Therefore, when the fuel cell system stops abnormally, it does not function. Remained, and there was a problem that hydrogen having a combustible concentration or more was exhausted.

  Further, in the conventional example disclosed in Patent Document 2, the effect of diffusion is aimed at by suppressing the flow rate of air exhausted at the time of starting the system and reducing the amount of exhausted hydrogen. Is not preferred because it is above the flammable concentration. Furthermore, since the air flow rate is suppressed and the hydrogen concentration is reduced by diffusion, there is a problem that the time required for activation becomes long.

  Further, in the conventional example disclosed in Patent Document 2, since air is bypassed and diluted from the upstream side of the fuel cell in the cathode path to the exhaust path, there is a problem that noise and vibration are generated by the compressor at the time of dilution. there were.

  Furthermore, in the conventional example disclosed in Patent Document 3, since dilution is performed by providing a dilution device such as a dilution volume part and a dilution blower, a space for installing a volume part for dilution, a blower for dilution, and the like. Is necessary, and there are significant disadvantages for mounting in a limited space such as mobile media.

In order to solve the above-described problems, a fuel cell system according to the present invention is a fuel cell system including a shut valve upstream of a cathode of the fuel cell and an air pressure regulating valve downstream of the cathode of the fuel cell, At the start of the battery, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and hydrogen in the cathode path is combusted on the catalyst in the cathode . A hydrogen dilution treatment for diluting is performed.

The fuel cell system activation method of the present invention is a fuel cell system activation method comprising a shut valve upstream of the fuel cell cathode and an air pressure regulating valve downstream of the fuel cell cathode, wherein the fuel cell At the time of start-up, oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and the hydrogen in the cathode path is diluted by burning on the catalyst in the cathode. A hydrogen dilution treatment is performed.

  In the fuel cell system according to the present invention, when the fuel cell is started, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and hydrogen in the cathode path is filled with the catalyst in the cathode. Because it is consumed and diluted by the combustion process above, the hydrogen that crosses over from the anode and accumulates in the cathode during standing after the system is stopped is suppressed from being discharged at a high concentration when the system is started. Can do.

  Embodiments of a fuel cell system and a fuel cell system activation method according to the present invention will be described below.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating the configuration of the fuel cell system according to the first embodiment.

  As shown in FIG. 1, the fuel cell system 1 of the present embodiment includes a fuel cell (FC) 2 that is supplied with a fuel gas and an oxidant gas and generates power by an electrochemical reaction, and an air that is an oxidant gas. A compressor 3 that supplies pressure to the cathode of the fuel cell 2, a shut valve 4 that shuts off supply of air from the compressor 3 to the fuel cell 2, and a pressure sensor that detects the pressure at the cathode inlet of the fuel cell 2 (pressure detection means) ) 5, a voltage estimation unit (voltage estimation unit) 6 that estimates the voltage generated by the fuel cell 2, a hydrogen concentration estimation unit (hydrogen concentration estimation unit) 7 that estimates the hydrogen concentration at the cathode of the fuel cell 2, And an air pressure regulating valve 8 for adjusting the pressure of air in the fuel cell 2.

  Here, in the fuel cell system 1 described above, in the fuel cell 2, hydrogen gas, which is fuel gas, is supplied to the anode, and air, which is oxidant gas, is supplied to the cathode, and power generation is performed by the following electrochemical reaction. ing.

Anode (fuel electrode): H2 → 2H ++ 2e- (1)
Cathode (oxidizer electrode): 2H ++ 2e-+ (1/2) O2 → H2O (2)
In the air system shown in FIG. 1, air is pressurized by the compressor 3 and supplied to the cathode of the fuel cell 2, and the pressure of the air at the cathode is detected by the pressure sensor 5, and based on this detected value. The air pressure at the cathode is controlled by adjusting the rotation speed of the compressor 3 and the opening area of the air pressure regulating valve 8.

  The voltage estimation unit 6 estimates the voltage generated by the fuel cell 2 and may be installed for each fuel cell or may be installed in the fuel cell stack.

  The hydrogen concentration estimation unit 7 estimates the concentration of hydrogen accumulated by crossing over from the anode to the cathode during the system stoppage, based on the cathode off gas discharged from the cathode.

  On the other hand, the route parts other than the air system described above may be general, and in the hydrogen system that supplies hydrogen as the fuel gas to the fuel cell 2, Hydrogen gas is supplied to the anode. The high-pressure hydrogen supplied from the hydrogen tank is mechanically reduced to a predetermined pressure by a pressure reducing valve, and then the hydrogen gas pressure in the fuel cell 2 becomes a desired pressure by adjusting the opening of the hydrogen supply valve. So that it is controlled.

  Next, the starting method by the fuel cell system 1 of the present embodiment will be described based on the flowchart of FIG. 2 and the timing chart of FIG.

  First, in a state where the fuel cell system 1 is stopped, all the valves are closed. Then, when the ignition is turned on to start the fuel cell system 1 as shown in FIG. 2 (S201, FIG. 3: T1), the hydrogen concentration estimation unit 7 estimates the hydrogen concentration A1 of the cathode (S202).

  Then, it is determined whether or not the estimated hydrogen concentration A1 is larger than the predetermined value α1 (S203). If the hydrogen concentration A1 is equal to or lower than the predetermined value α1, it is determined that the process of diluting hydrogen is unnecessary. Then, normal power generation is started (S204). Here, the predetermined value α1 is set to a value having a margin below the lower limit value of the flammable concentration of hydrogen. In addition, it is not determined whether or not hydrogen dilution processing is necessary based on the hydrogen concentration, but whether or not hydrogen dilution processing is necessary depending on the time from when the fuel cell 2 was previously stopped to when it is started this time. May be determined. Accordingly, it is possible to determine the presence or absence of the hydrogen dilution treatment by a simpler method.

  On the other hand, if the hydrogen concentration A1 is larger than the predetermined value α1 in step S203, it is determined that the process of diluting hydrogen is necessary, and the shut valve 4 is opened (S205, FIG. 3: T2), and the compressor 3 is turned on. It drives and supplies air to the cathode of the fuel cell 2 (S206, FIG. 3: T3). At this time, since the air pressure regulating valve 8 is closed, the pressure is increased upstream of the air pressure regulating valve 8.

  Next, the pressure sensor 5 detects the pressure B1 in the cathode path (S207), and determines whether or not the detected pressure B1 is greater than a predetermined value β1 (S208).

  When the pressure B1 becomes larger than the predetermined value β1, the shut valve 4 is closed (S209, FIG. 3: T4), and the supply of air is stopped (S210). Here, as a method of setting the predetermined value β1, the amount of hydrogen is estimated from the volume of the cathode path between the air pressure regulating valve 8 and the shut valve 4 and the hydrogen concentration estimated by the hydrogen concentration estimating unit 7, and this hydrogen The pressure generated when the amount of oxygen necessary for consuming the amount by catalytic reaction is sealed in the cathode path is set as the predetermined value β1.

  When the shut valve 4 is closed in this way, a mixed gas of air and hydrogen is sealed in the cathode path between the air pressure regulating valve 8 and the shut valve 4 in a pressurized state. In this state, oxygen and hydrogen are supplied by diffusion on the catalyst in the fuel cell 2 and a catalytic reaction occurs.

  In this state, the hydrogen concentration estimation unit 7 estimates the hydrogen concentration C1 of the cathode path (S211), and determines whether the estimated hydrogen concentration C1 is smaller than the predetermined value γ1 (S212). Here, the predetermined value γ1 is set to a value having a margin sufficiently lower than the lower limit value of the flammable concentration of hydrogen.

  When the hydrogen concentration C1 becomes smaller than the predetermined value γ1, it is determined that the process of diluting hydrogen is completed, the shut valve 4 is opened (S213, FIG. 3: T5), and air and hydrogen are supplied (S214). , FIG. 3: T5) When normal power generation is started (S204, FIG. 3: T6), the start-up process by the fuel cell system 1 of this embodiment is terminated.

As described above, in the fuel cell system 1 of this embodiment, when the fuel cell 2 is started, air is pumped and sealed between the shut valve 4 and the air pressure regulating valve 8 until a predetermined pressure is reached, and is in the cathode path. Since hydrogen is diluted by consuming it in the fuel cell 2, the hydrogen that crosses over from the anode and accumulates in the cathode while the system is stopped is burned on the catalyst in the cathode of the fuel cell 2. it can be a high concentration of hydrogen from the cathode Ru can be suppressed to be discharged at system startup.

Further, in the fuel cell system 1 of this embodiment, in order to estimate the amount of hydrogen from the hydrogen concentration estimated by the hydrogen concentration estimating unit 7 and the volume of the cathode path to be enclosed, and to consume this hydrogen amount by catalytic reaction Since the pressure generated when the necessary amount of oxygen is sealed in the cathode path is set as the predetermined pressure β1, the oxygen necessary for burning the hydrogen accumulated on the cathode after crossing over from the anode after the system is stopped on the catalyst. Ru can be supplied without shortage.

Furthermore, in the fuel cell system 1 of the present embodiment, since it is determined whether or not the hydrogen dilution process is completed based on the hydrogen concentration estimated by the hydrogen concentration estimation unit 7, the system does not require more time than necessary. Ru can be kept low concentration of hydrogen gas discharged from the cathode at startup.

Further, in the fuel cell system 1 of the present embodiment, it is determined whether or not the hydrogen dilution process is to be performed based on the hydrogen concentration estimated by the hydrogen concentration estimation unit 7, so whether or not hydrogen dilution is necessary. the can be accurately determined, it may be shortened start-up time of the system when the dilution of hydrogen is not required.

Furthermore, in the fuel cell system 1 of the present embodiment, it is determined whether or not the hydrogen dilution process is performed depending on the time from when the fuel cell 2 is stopped to when it is started. It can determine whether in a simple manner, may be shortened start-up time of the system when the dilution of hydrogen is not required.

  Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram illustrating a configuration of the fuel cell system according to the second embodiment. As shown in FIG. 4, the fuel cell system 41 of this embodiment includes a circulation path 42 that circulates the cathode off-gas from the cathode outlet of the fuel cell to the cathode inlet, and a circulation pump 43 that circulates the gas in the circulation path 42. Is different from the first embodiment, and other configurations are the same as those of the first embodiment, and thus detailed description thereof is omitted.

  In the fuel cell system 41 of the present embodiment, when the fuel cell 2 is started, air is pumped and sealed between the shut valve 4 and the air pressure regulating valve 8 until a predetermined pressure is reached, and the sealed gas is fed by the circulation pump 43. It is made to circulate and the hydrogen dilution process is implemented.

  Next, the starting method by the fuel cell system 41 of the present embodiment will be described based on the flowchart of FIG. 5 and the timing chart of FIG.

  First, in a state where the fuel cell system 41 is stopped, all the valves are closed. Then, as shown in FIG. 5, when the ignition is turned on to start the fuel cell system 41 (S501, FIG. 6: T1), the hydrogen concentration estimation unit 7 estimates the hydrogen concentration A2 (S502).

  Then, it is determined whether or not the estimated hydrogen concentration A2 is larger than the predetermined value α2 (S503). If the hydrogen concentration A2 is equal to or lower than the predetermined value α2, it is determined that the process of diluting hydrogen is unnecessary. Then, normal power generation is started (S504). Here, the predetermined value α2 is set to a value having a margin below the lower limit value of the flammable concentration of hydrogen.

  On the other hand, if the hydrogen concentration A2 is larger than the predetermined value α2 in step S503, it is determined that the process of diluting hydrogen is necessary, the shut valve 4 is opened (S505, FIG. 6: T2), and the compressor 3 is turned on. It drives and supplies air to the cathode of the fuel cell 2 (S506, FIG. 6: T3). At this time, since the air pressure regulating valve 8 is closed, the pressure is increased upstream of the air pressure regulating valve 8. Further, at this time, the circulation pump 43 is driven (S507, FIG. 6: T3), and the gas in the cathode path and the circulation path 42 is circulated.

  Next, the pressure sensor 5 detects the pressure B2 in the cathode path (S508), and determines whether or not the detected pressure B2 is greater than a predetermined value β2 (S509).

  When the pressure B2 becomes larger than the predetermined value β2, the shut valve 4 is closed (S510, FIG. 6: T4), and the supply of air is stopped (S511). Here, as a method of setting the predetermined value β2, a hydrogen amount is estimated from the volume of the cathode path between the air pressure regulating valve 8 and the shut valve 4 and the hydrogen concentration estimated by the hydrogen concentration estimating unit 7, and this hydrogen The pressure generated when the amount of oxygen necessary for consuming the amount by catalytic reaction is enclosed in the cathode path or the circulation path 42 is set as the predetermined value β2.

  When the shut valve 4 is closed in this manner, the mixed gas of air and hydrogen is sealed in the cathode path and the circulation path 42 between the air pressure regulating valve 8 and the shut valve 4 in a pressurized state. In this state, oxygen and hydrogen are supplied by diffusion on the catalyst in the fuel cell 2 and a catalytic reaction occurs. Furthermore, since the gas sealed by the circulation pump 43 is circulated, the diffusion of hydrogen and oxygen can be promoted and burned on the catalyst more quickly.

  In this state, the hydrogen concentration estimation unit 7 estimates the hydrogen concentration C2 of the cathode path (S512), and determines whether or not the estimated hydrogen concentration C2 is smaller than the predetermined value γ2 (S513). Here, the predetermined value γ2 is set to a value with a margin sufficiently lower than the lower limit value of the flammable concentration of hydrogen.

  When the hydrogen concentration C2 becomes smaller than the predetermined value γ2, it is determined that the process of diluting hydrogen is completed, the shut valve 4 is opened (S514, FIG. 6: T5), and air and hydrogen are supplied (S515). FIG. 6: T5) When normal power generation is started (S504, FIG. 6: T6), the start-up process by the fuel cell system 41 of this embodiment is terminated.

As described above, the fuel cell system 41 of the present embodiment further includes the circulation path 42 that circulates the gas from the cathode outlet to the cathode inlet of the fuel cell 2 and the circulation pump 43 that circulates the gas in the circulation path 42. When the fuel cell 2 is started, air is pumped and sealed between the shut valve 4 and the air pressure regulating valve 8 until a predetermined pressure is reached, and the sealed gas is circulated by the circulation pump 43 to perform the hydrogen dilution process. Therefore, the hydrogen accumulated in the cathode by crossing over from the anode while the system is stopped can be burned on the catalyst in the cathode of the fuel cell, and high-concentration hydrogen is discharged from the cathode when the system is started. Can be suppressed. Furthermore, by circulating the encapsulated gas circulation path 42, that Do can be burned on the earlier catalyst to promote the diffusion of hydrogen and oxygen.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 7 is a block diagram illustrating the configuration of the fuel cell system according to the third embodiment. As shown in FIG. 7, the fuel cell system 71 according to the present embodiment includes a second shut valve 72 provided upstream of the circulation pump 43 in the circulation path 42, and an external portion between the circulation pump 43 and the second shut valve 72. The second embodiment is different from the second embodiment in that it includes a suction path 73 for sucking air from, a foreign matter filter 74 installed in the suction path 73, and a third shut valve 75 installed in the suction path 73. Since the configuration is the same as that of the second embodiment, detailed description thereof is omitted.

  In the fuel cell system 71 of this embodiment, when the fuel cell 2 is started, air is sucked in from the outside through the suction path 73 between the shut valve 4 and the air pressure regulating valve 8, and the third shut valve 75 is closed when a predetermined pressure is reached. The hydrogen dilution process is performed by circulating the gas sealed by the circulation pump 43.

  Next, the starting method by the fuel cell system 71 of the present embodiment will be described based on the flowchart of FIG. 8 and the timing chart of FIG.

  First, in a state where the fuel cell system 71 is stopped, all the valves are closed. Then, as shown in FIG. 8, when the ignition is turned on to start the fuel cell system 71 (S801, FIG. 9: T1), the hydrogen concentration estimation unit 7 estimates the hydrogen concentration A3 (S802).

  Then, it is determined whether or not the estimated hydrogen concentration A3 is larger than the predetermined value α3 (S803). If the hydrogen concentration A3 is equal to or lower than the predetermined value α3, it is determined that the process of diluting hydrogen is unnecessary. Then, normal power generation is started (S804). Here, the predetermined value α3 is set to a value having a margin below the lower limit value of the flammable concentration of hydrogen.

  On the other hand, if the hydrogen concentration A3 is larger than the predetermined value α3 in step S803, it is determined that a process for diluting hydrogen is necessary, and the third shut valve 75 is opened (S805, FIG. 9: T2), and circulation is performed. The pump 43 is driven (S806, FIG. 9: T3), and air is sucked from the outside through the suction path 73 and supplied to the cathode of the fuel cell 2. At this time, since the shut valve 4, the air pressure regulating valve 8, and the second shut valve 72 are closed, the pressure is increased on the upstream side of the air pressure regulating valve 8.

  Next, the pressure sensor 3 detects the pressure B3 in the cathode path (S807), and determines whether or not the detected pressure B3 is greater than a predetermined value β3 (S808).

  When the pressure B3 becomes larger than the predetermined value β3, the third shut valve 75 is closed (S809, FIG. 9: T4), the air suction is stopped, and the second shut valve 72 is opened (S810). Here, as a method of setting the predetermined value β3, the amount of hydrogen is estimated from the volume of the cathode path between the air pressure regulating valve 8 and the shut valve 4 and the hydrogen concentration estimated by the hydrogen concentration estimating unit 7, and this hydrogen The pressure generated when the amount of oxygen necessary for consuming the amount by catalytic reaction is enclosed in the cathode path or the circulation path 42 is set as the predetermined value β3.

  Thus, when the third shut valve 75 is closed and the second shut valve 72 is opened, the mixed gas of air and hydrogen is pressurized in the cathode path and the circulation path 42 between the air pressure regulating valve 8 and the shut valve 4. Will be enclosed. In this state, oxygen and hydrogen are supplied by diffusion on the catalyst in the fuel cell 2 and a catalytic reaction occurs. Furthermore, since the gas sealed by the circulation pump 43 is circulated, the diffusion of hydrogen and oxygen can be promoted and burned on the catalyst more quickly.

  In this state, the hydrogen concentration estimation unit 7 estimates the hydrogen concentration C3 of the cathode path (S811), and determines whether or not the estimated hydrogen concentration C3 is smaller than the predetermined value γ3 (S812). Here, the predetermined value γ3 is set to a value having a margin sufficiently lower than the lower limit value of the flammable concentration of hydrogen.

  When the hydrogen concentration C3 becomes smaller than the predetermined value γ3, it is determined that the process of diluting hydrogen is completed, the shut valve 4 is opened (S813, FIG. 9: T5), and air and hydrogen are supplied (S814). , FIG. 9: T5) When normal power generation is started (S804, FIG. 6: T6), the start-up process by the fuel cell system 71 of this embodiment is terminated.

As described above, in the fuel cell system 71 of this embodiment, the circulation path 42 is further provided with the suction path 73 for sucking air from the outside, and oxidation is performed between the shut valve 4 and the air pressure regulating valve 8 when the fuel cell 2 is started. Since the agent gas is sucked from the outside through the suction path 73 until it reaches a predetermined pressure and sealed, and the sealed gas is circulated by the circulation pump 43 to carry out the hydrogen dilution treatment, the gas is crossed from the anode while being left after the system is stopped. The hydrogen accumulated over the cathode can be combusted on the catalyst in the cathode of the fuel cell, and high concentration hydrogen can be prevented from being discharged from the cathode when the system is started. Furthermore, by circulating the gas sealed in the circulation path 42, diffusion of hydrogen and oxygen can be promoted and burned on the catalyst more quickly. Further, since the intake air without using the compressor 3, to prevent noise and vibration due to the driving of the compressor 3, Ru can be reduced power consumption.

  Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a flowchart illustrating a starting method of the fuel cell system according to the fourth embodiment. In addition, since the structure of the fuel cell system of a present Example is the same as Example 1, detailed description is abbreviate | omitted.

  In the first embodiment described above, it is determined whether or not the hydrogen dilution process is performed based on the hydrogen concentration estimated by the hydrogen concentration estimating unit 7. However, in the fuel cell system of the present embodiment, the voltage estimating unit 6 Based on the estimated voltage, it is determined whether or not to perform a hydrogen dilution process.

  Similarly, whether or not the hydrogen dilution process is completed is also determined based on the hydrogen concentration in the first embodiment, but is determined based on the voltage estimated by the voltage estimation unit 6 in the present embodiment. Like to do.

  Next, the starting method by the fuel cell system of the present embodiment will be described based on the flowchart of FIG. As shown in FIG. 10, in the starting method by the fuel cell system of the present embodiment, in step S1002, the voltage D generated by the fuel cell 2 is estimated by the voltage estimation unit 6, and the voltage D estimated in step S1003 is a predetermined value. It is determined whether or not it is larger than the value α4. Here, the predetermined value α4 is set to a voltage value generated by the fuel cell 2 when hydrogen is present in a combustible concentration or more.

  When the voltage D is equal to or lower than the predetermined value α4, it is determined that the process of diluting hydrogen is unnecessary, and normal power generation is started (S1004). When the voltage D is higher than the predetermined value α4, Then, it is determined that the process of diluting hydrogen is necessary, and the shut valve 4 is opened (S1005), and the hydrogen dilution process shown in steps S1005 to S1010 is performed. Since this hydrogen dilution process is the same as that of Example 1, detailed description is abbreviate | omitted.

  In this way, the hydrogen dilution process is performed, and the voltage E generated by the fuel cell 2 is estimated by the voltage estimation unit 6 in step S1011, and it is determined whether or not the estimated voltage is smaller than the predetermined value γ4 in step S1012. Here, the predetermined value γ4 is set to a voltage value generated by the fuel cell 2 when hydrogen is present in a flammable concentration or more.

  When the voltage E becomes smaller than the predetermined value γ4, it is determined that the hydrogen dilution process has been completed, normal power generation is started (S1004), and the start-up process by the fuel cell system of this embodiment is terminated.

As described above, in the fuel cell system of the present embodiment, since it is determined whether or not the hydrogen dilution processing is completed based on the voltage estimated by the voltage estimation unit 6, it is necessary without using the hydrogen concentration estimation unit 7. without requiring more time, Ru can be suppressed to be low concentration of hydrogen discharged from the cathode at system startup.

Further, in the fuel cell system of the present embodiment, since it is determined whether or not the hydrogen dilution process is performed based on the voltage estimated by the voltage estimation unit 6, the hydrogen concentration is estimated based on the output of the voltage estimation unit 6. to Ru it can determine whether to perform the hydrogen dilution process in a more simple way.

  Next, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a flowchart illustrating a starting method of the fuel cell system according to the fifth embodiment. In addition, since the structure of the fuel cell system of a present Example is the same as Example 1, detailed description is abbreviate | omitted.

  In the first embodiment described above, it is determined whether or not the hydrogen dilution process is to be performed based on the hydrogen concentration estimated by the hydrogen concentration estimating unit 7. In the fuel cell system of the present embodiment, the detection is performed by the pressure sensor 5. Whether or not to carry out the hydrogen dilution process is determined based on the applied pressure.

  Similarly, whether or not the hydrogen dilution process is completed is also determined based on the hydrogen concentration in the first embodiment, but is determined based on the pressure detected by the pressure sensor 5 in the present embodiment. I am doing so.

  Next, the starting method by the fuel cell system of the present embodiment will be described based on the flowchart of FIG. As shown in FIG. 11, in the starting method by the fuel cell system of the present embodiment, the pressure F in the cathode path is detected by the pressure sensor 5 in step S1102, and is the detected pressure F in step S1103 greater than a predetermined value α5? It is determined whether or not. Here, the predetermined value α5 is set to a pressure when hydrogen is present at a flammable concentration or more.

  When the pressure F is equal to or lower than the predetermined value α5, it is determined that the process of diluting hydrogen is unnecessary, and normal power generation is started (S1104). When the pressure F is higher than the predetermined value α5, Then, it is determined that the process of diluting hydrogen is necessary, and the shut valve 4 is opened (S1105), and the hydrogen dilution process shown in steps S1105 to S1110 is performed. Since this hydrogen dilution process is the same as that of Example 1, detailed description is abbreviate | omitted.

  Thus, the hydrogen dilution process is performed, and the pressure G in the cathode path is detected by the pressure sensor 5 in step S1111, and it is determined whether or not the pressure G detected in step S1112 is smaller than a predetermined value γ5. Here, the predetermined value γ5 is set to a pressure when hydrogen is present in a flammable concentration or more.

When the pressure G becomes smaller than the predetermined value γ5, it is determined that the hydrogen dilution process is completed, and normal power generation is started (S1104), and the start-up process by the fuel cell system of this embodiment is terminated.

  Whether the hydrogen dilution process is performed in step S1103 based on both the voltage value estimated by the voltage estimation unit 6 described in the fourth embodiment and the pressure detected by the pressure sensor 5 described in the present embodiment. It may be determined whether or not.

  Further, whether or not the hydrogen dilution process in step S1112 has been completed may also be determined based on both the voltage value estimated by the voltage estimation unit 6 and the pressure detected by the pressure sensor 5.

As described above, in the fuel cell system of this embodiment, it is determined whether or not the hydrogen dilution process is completed based on the pressure detected by the pressure sensor 5, so that it is more than necessary without using the hydrogen concentration estimation unit 7. without requiring time, Ru can be suppressed to be low concentration of hydrogen discharged from the cathode at system startup.

Further, in the fuel cell system of the present embodiment, it is determined whether or not the hydrogen dilution process is completed based on the voltage estimated by the voltage estimation unit 6 and the pressure detected by the pressure sensor 5, so that the hydrogen concentration estimation without requiring more time than necessary without the use of parts 7, Ru can be suppressed to be low concentration of hydrogen discharged from the cathode to more accurately system startup.

Furthermore, in the fuel cell system of the present embodiment, it is determined whether or not to perform the hydrogen dilution process based on the pressure detected by the pressure sensor 5, so the hydrogen concentration is estimated based on the output of the pressure sensor 5. Ru can determine whether to perform the hydrogen dilution process in a more simple way.

Further, in the fuel cell system of the present embodiment, since it is determined whether or not the hydrogen dilution process is performed based on the voltage estimated by the voltage estimation unit 6 and the pressure detected by the pressure sensor 5, the voltage estimation unit Ru can determine whether to perform more precisely hydrogen dilution process by estimating the hydrogen concentration based on both outputs of the 6 and the pressure sensor 5.

  Although the fuel cell system of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. Can do.

It is a block diagram which shows the structure of the fuel cell system which concerns on Example 1 of this invention. It is a flowchart which shows the starting method by the fuel cell system which concerns on Example 1 of this invention. It is a timing chart for demonstrating the starting method by the fuel cell system which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on Example 2 of this invention. It is a flowchart which shows the starting method by the fuel cell system which concerns on Example 2 of this invention. It is a timing chart for demonstrating the starting method by the fuel cell system which concerns on Example 2 of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on Example 3 of this invention. It is a flowchart which shows the starting method by the fuel cell system which concerns on Example 3 of this invention. It is a timing chart for demonstrating the starting method by the fuel cell system which concerns on Example 3 of this invention. It is a flowchart which shows the starting method by the fuel cell system which concerns on Example 4 of this invention. It is a flowchart which shows the starting method by the fuel cell system which concerns on Example 5 of this invention.

Explanation of symbols

1, 41, 71 Fuel cell system 2 Fuel cell 3 Compressor 4 Shut valve 5 Pressure sensor (pressure detection means)
6 Voltage estimation unit (voltage estimation means)
7 Hydrogen concentration estimation part (hydrogen concentration estimation means)
8 Air pressure regulating valve 42 Circulation path 43 Circulation pump 72 Second shut valve 73 Suction path 74 Foreign matter filter 75 Third shut valve

Claims (18)

A fuel cell system comprising a shut valve upstream of the cathode of the fuel cell and an air pressure regulating valve downstream of the cathode of the fuel cell,
When starting the fuel cell, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and the hydrogen in the cathode path is burned on the catalyst in the cathode. A fuel cell system for carrying out a hydrogen dilution treatment for diluting by the above. A circulation path for circulating gas from the cathode outlet of the fuel cell to the cathode inlet, and a circulation pump for circulating gas in the circulation path;
At the time of starting the fuel cell, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and the sealed gas is circulated by the circulation pump to perform the hydrogen dilution process. The fuel cell system according to claim 1, wherein: The circulation path further comprises a suction path for sucking oxidant gas from the outside,
At the time of starting the fuel cell, an oxidant gas is sucked from outside through the suction path until the pressure reaches a predetermined pressure between the shut valve and the air pressure regulating valve, and the sealed gas is circulated by the circulation pump. The fuel cell system according to claim 2, wherein the hydrogen dilution process is performed. Comprising hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell;
When the amount of hydrogen is estimated from the hydrogen concentration estimated by the hydrogen concentration estimating means and the volume of the enclosed cathode passage, and the amount of oxygen necessary to consume this amount of hydrogen by catalytic reaction is enclosed in the cathode passage The fuel cell system according to any one of claims 1 to 3, wherein a pressure generated in the fuel cell is set to the predetermined pressure. Comprising hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell;
The fuel cell system according to any one of claims 1 to 4, wherein it is determined whether or not the hydrogen dilution process is completed based on the hydrogen concentration estimated by the hydrogen concentration estimating means. . Pressure detecting means for detecting the pressure of the gas sealed between the shut valve and the air pressure regulating valve;
The fuel cell system according to any one of claims 1 to 4, wherein it is determined whether or not the hydrogen dilution process is completed based on a pressure detected by the pressure detection means. Comprising hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell;
Based on the hydrogen concentration estimated by the hydrogen concentration estimating means, fuel cell according to any one of claims 1 to 6, characterized in that determining whether to execute the hydrogen dilution process system. Pressure detecting means for detecting the pressure of the gas sealed between the shut valve and the air pressure regulating valve;
The fuel cell system according to any one of claims 1 to 6 , wherein it is determined whether or not to perform the hydrogen dilution processing based on a pressure detected by the pressure detection means. The fuel according to any one of claims 1 to 6 , wherein it is determined whether or not to perform the hydrogen dilution processing according to a time from when the fuel cell is stopped to when it is started. Battery system. A fuel cell system start-up method comprising a shut valve upstream of a fuel cell cathode and an air pressure regulating valve downstream of the fuel cell cathode,
When starting the fuel cell, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and the hydrogen in the cathode path is burned on the catalyst in the cathode. A start-up method for a fuel cell system, characterized in that a hydrogen dilution process for diluting is performed. The fuel cell system further comprises a circulation path for circulating gas from the cathode outlet to the cathode inlet of the fuel cell, and a circulation pump for circulating gas in the circulation path,
At the time of starting the fuel cell, an oxidant gas is pumped and sealed between the shut valve and the air pressure regulating valve until a predetermined pressure is reached, and the sealed gas is circulated by the circulation pump to perform the hydrogen dilution process. The start method of the fuel cell system according to claim 10 , wherein: The fuel cell system further includes a suction path for sucking an oxidant gas from the outside in the circulation path,
At the time of starting the fuel cell, an oxidant gas is sucked from outside through the suction path until the pressure reaches a predetermined pressure between the shut valve and the air pressure regulating valve, and the sealed gas is circulated by the circulation pump. The method according to claim 11 , wherein the hydrogen dilution process is performed. The fuel cell system comprises hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell,
When the amount of hydrogen is estimated from the hydrogen concentration estimated by the hydrogen concentration estimating means and the volume of the enclosed cathode passage, and the amount of oxygen necessary to consume this amount of hydrogen by catalytic reaction is enclosed in the cathode passage The method for starting the fuel cell system according to any one of claims 10 to 12 , wherein a pressure generated in the fuel cell is set to the predetermined pressure. The fuel cell system comprises hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell,
The fuel cell system according to any one of claims 10 to 13 , wherein it is determined whether or not the hydrogen dilution process is completed based on the hydrogen concentration estimated by the hydrogen concentration estimating means. How to start. The fuel cell system includes pressure detection means for detecting the pressure of gas sealed between the shut valve and the air pressure regulating valve,
The start of the fuel cell system according to any one of claims 10 to 13 , wherein it is determined whether or not the hydrogen dilution process is completed based on the pressure detected by the pressure detection means. Method. The fuel cell system comprises hydrogen concentration estimating means for estimating the hydrogen concentration at the cathode of the fuel cell,
The fuel cell according to any one of claims 10 to 15 , wherein it is determined whether or not to perform the hydrogen dilution processing based on the hydrogen concentration estimated by the hydrogen concentration estimation means. How to start the system. The fuel cell system includes pressure detection means for detecting the pressure of gas sealed between the shut valve and the air pressure regulating valve,
The fuel cell system according to any one of claims 10 to 15 , wherein whether or not to perform the hydrogen dilution processing is determined based on a pressure detected by the pressure detection means. starting method. The fuel according to any one of claims 10 to 15 , wherein whether or not to perform the hydrogen dilution processing is determined according to a time from when the fuel cell is stopped to when it is started. How to start the battery system.

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