JP2010049915A - Fuel cell system and scavenging method for the same - Google Patents

Abstract

A scavenging method for a fuel cell system capable of performing a scavenging process at an appropriate timing.
A cooling water temperature change rate detecting step for detecting a cooling water temperature change rate using a detection value in a cooling water temperature detecting step S14, and a fuel cell temperature using a detection value in an anode gas temperature detecting step S12. A determination step S18 for determining whether or not the cooling water temperature change rate detected in the cooling water temperature change rate detection step S16 is less than or equal to a predetermined temperature change rate, as well as determining whether or not the first predetermined temperature or lower; The scavenging step S22 performs scavenging when it is determined in the determination step S18 that the temperature of the fuel cell is equal to or lower than the first predetermined temperature and the cooling water temperature change rate is equal to or lower than the predetermined temperature change rate.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell system and a scavenging method for the fuel cell system.

  In a fuel cell, a membrane electrode structure is formed by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode from both sides, and a pair of separators are arranged on both sides of the membrane electrode structure to form a flat unit fuel. A battery (hereinafter referred to as “unit cell”) is configured, and a plurality of unit cells are stacked to form a fuel cell stack. In this fuel cell, a hydrogen gas is supplied as a fuel gas to an anode gas passage formed between the anode electrode and the anode side separator, and a cathode gas passage formed between the cathode electrode and the cathode side separator. Is supplied with air as an oxidant gas. As a result, hydrogen ions generated by the catalytic reaction at the anode electrode permeate the solid polymer electrolyte membrane and move to the cathode electrode, and the cathode electrode causes an electrochemical reaction with oxygen in the air to generate power. Further, water is generated along with this power generation (hereinafter referred to as generated water).

In this type of fuel cell, the generated water (hereinafter referred to as residual water) remaining in the reaction gas channel (fuel gas channel and oxidant gas channel) is used to supply fuel gas and oxidant gas to the membrane electrode structure. This hinders power generation performance. When the fuel cell is driven below freezing point, the power generation area in the membrane electrode structure is reduced due to the freezing of the residual water, thereby reducing the power generation performance.
Therefore, a technique has been proposed in which scavenging gas is supplied into the reaction gas flow path to remove residual water. It is necessary to perform scavenging before the temperature of the fuel cell falls below freezing point. Therefore, Patent Document 1 discloses a technique for determining the scavenging timing in the anode gas flow path with a temperature sensor (absolute value) in the cooling system.
US Pat. No. 7,270,904

However, when an offset failure occurs in the temperature sensor, the temperature of the fuel cell cannot be accurately detected. Therefore, there is a problem that it becomes difficult to perform scavenging before the fuel cell becomes below freezing point. In this case, since the generated water freezes inside the fuel cell stack, the startability and power generation performance of the fuel cell system are deteriorated.
Therefore, an object of the present invention is to provide a fuel cell system capable of performing a scavenging process at an appropriate timing and a scavenging method therefor.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a reactive gas flow path (for example, the anode gas flow path 11 or the cathode gas flow path 12 in the embodiment) to a reactive gas (for example, hydrogen gas in the embodiment or A fuel cell (for example, the fuel cell 1 in the embodiment) that supplies power by supplying air) and a cooling fluid (for example, a coolant channel (for example, the refrigerant channel 40 in the embodiment) inside the fuel cell) Cooling water in the embodiment), scavenging gas supply means (for example, the air compressor 7 in the embodiment) for supplying a scavenging gas (for example, air in the embodiment) to the reaction gas flow path, and power generation of the fuel cell. A scavenging control unit (for example, the controller 60 in the embodiment) for scavenging the inside of the fuel cell with the scavenging gas in a stopped state. A fuel cell system (for example, the fuel cell system 100 in the embodiment), a reaction gas temperature detection means (for example, an anode gas temperature sensor T1 in the embodiment) for detecting the temperature of the reaction gas, and a temperature of the cooling fluid A cooling fluid temperature detection means (for example, a cooling water temperature sensor T3 in the embodiment), and a detection value of one of a detection value of the reaction gas temperature detection means or a detection value of the cooling fluid temperature detection means ( For example, a first determination unit that determines whether or not the temperature of the fuel cell is equal to or lower than a first predetermined temperature (for example, the first predetermined temperature A1 in the embodiment) using the anode gas temperature TH in the embodiment. For example, the controller 60) in the embodiment and the other detection value not used in the first determination unit (for example, in the embodiment). A temperature change rate detecting means (for example, the controller 60 in the embodiment) for detecting a temperature change rate (for example, a TW change rate in the embodiment) using the cooling water temperature TW), and the first determination unit of the fuel cell. When the temperature is determined to be equal to or lower than the first predetermined temperature, the temperature change rate detected by the temperature change rate detecting means is equal to or lower than a predetermined temperature change rate (for example, the predetermined temperature change rate D in the embodiment). A second determination unit (for example, the controller 60 in the embodiment) for determining whether or not the scavenging control unit has a temperature change rate equal to or lower than the predetermined temperature change rate by the second determination unit. Scavenging is performed when it is determined that.

  The invention according to claim 2 is characterized in that the determination by the second determination unit is not performed when the first determination unit determines that the temperature of the fuel cell exceeds the first predetermined temperature. To do.

  In the invention according to claim 3, in the first determination unit, it is determined that the temperature of the fuel cell is equal to or lower than a second predetermined temperature (for example, a second predetermined temperature A2 in the embodiment) lower than the first predetermined temperature. If it is, scavenging is performed by the scavenging control unit.

  According to a fourth aspect of the present invention, there is provided a fuel cell that generates a power by supplying a reaction gas to a reaction gas channel, a cooling fluid supplied to a refrigerant channel inside the fuel cell, and a scavenging gas to the reaction gas channel. Scavenging gas supply means for supplying, scavenging control unit for scavenging the inside of the fuel cell with the scavenging gas in a state where power generation of the fuel cell is stopped, and reaction gas temperature detection for detecting the temperature of the reaction gas And a cooling fluid temperature detection means for detecting the temperature of the cooling fluid, the scavenging method of the fuel cell system, wherein the reaction gas temperature detection means detects the temperature of the reaction gas by the reaction gas temperature detection means (For example, the anode gas temperature detection step S12 in the embodiment) and the cooling fluid temperature detection step (for example, in the embodiment, the temperature of the cooling fluid is detected by the cooling fluid temperature detection means). The temperature of the fuel cell is set to a first predetermined temperature using one of a detection value of the cooling water temperature detection step S14), a detection value of the reaction gas temperature detection step, or a detection value of the cooling fluid temperature detection step. A temperature change that detects a rate of temperature change using a first determination step (for example, determination step S18 in the embodiment) for determining whether or not it is below and the other detection value that is not used in the first determination step. When the rate detection step (for example, the cooling water temperature change rate detection step S16 in the embodiment) and the first determination step determine that the temperature of the fuel cell is equal to or lower than the first predetermined temperature, the temperature change A second determination step (for example, determination step S18 in the embodiment) for determining whether or not the temperature change rate detected in the rate detection step is equal to or less than a predetermined temperature change rate; and the second determination step When it is determined that the temperature change rate is below the predetermined temperature change rate have, scavenging of performing scavenging by the scavenging control section (e.g., scavenging reaction process S22 in the embodiment) and is characterized by having a.

  The invention according to claim 5 is characterized in that in the first determination step, when it is determined that the temperature of the fuel cell exceeds the first predetermined temperature, the determination in the second determination step is not performed.

  According to a sixth aspect of the present invention, when it is determined in the first determination step that the temperature of the fuel cell is equal to or lower than a second predetermined temperature lower than the first predetermined temperature, the scavenging step is performed. Features.

According to the first or fourth aspect of the present invention, the temperature of the fuel cell is set to the first predetermined temperature by using one of the detection value of the reaction gas temperature detection means and the detection value of the cooling fluid temperature detection means. Since it is determined whether or not it is below, even when an offset failure occurs in the other temperature detecting means, the scavenging process can be performed at an appropriate timing before the fuel cell becomes below freezing point.
Further, when it is determined that the temperature change rate is equal to or lower than the predetermined temperature change rate, the temperature of the fuel cell is in a soaking state close to the outside air temperature, and water vapor in the fuel cell is condensed to the maximum. . By performing the scavenging process in this state, the generated water in the fuel cell can be efficiently removed. Even when an offset failure occurs in the temperature detecting means, it is possible to accurately grasp that the fuel cell is in a soaking state by detecting the temperature change rate.

  According to the invention according to claim 2 or 5, when the temperature of the fuel cell exceeds the first predetermined temperature, there is no possibility that the generated water will freeze in the fuel cell. Energy consumption can be prevented.

  According to the invention of claim 3 or 6, even when the outside air temperature is extremely low and the temperature change rate does not fall below the predetermined temperature change rate, the scavenging process can be performed at an appropriate timing before the fuel cell becomes below freezing point. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Fuel cell system)
FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system. The fuel cell system 100 includes a fuel cell 1 that supplies a cathode gas and an anode gas to generate power. The fuel cell 1 is formed by stacking a number of unit fuel cells (hereinafter referred to as “unit cells”) and electrically connecting them in series. The unit cell has a sandwich structure in which separators are arranged on both sides of the membrane electrode structure. Specifically, the membrane electrode structure is configured by arranging an anode electrode and a cathode electrode on both sides of a solid polymer electrolyte membrane (electrolyte membrane) made of, for example, a fluorine-based electrolyte material. An anode-side separator is disposed facing the anode electrode of the membrane electrode structure, and an anode gas flow path 11 is formed therebetween. A cathode-side separator is disposed facing the cathode electrode of the membrane electrode structure, and a cathode gas flow path 12 is formed between them.

  In this fuel cell 1, a fuel gas such as hydrogen gas is supplied as an anode gas to the anode gas flow path 11, and an oxidant gas such as air containing oxygen is supplied as the cathode gas flow path 12 to the cathode gas flow path 12. Then, hydrogen ions generated by the catalytic reaction at the anode electrode pass through the solid polymer electrolyte membrane and move to the cathode electrode. The hydrogen ions cause an electrochemical reaction with oxygen at the cathode electrode to generate power, and water is generated on the cathode electrode side with the power generation.

  A fuel gas supply path 17 is connected to the inlet side of the anode gas flow path 11 of the fuel cell 1. The fuel gas supply path 17 includes a hydrogen tank 15, an electromagnetic shut-off valve (not shown) that shuts off the flow of the fuel gas, a pressure-reducing valve (not shown) that decompresses the fuel gas according to the pressure of the oxidant gas, A filter (not shown) that removes impurities in the fuel gas supply path 17, a heat exchanger (not shown) that adjusts the temperature of the fuel gas, and an ejector 19 that joins the anode off-gas to the fuel gas supply path 17, It is provided in order.

An anode circulation path 18 is provided from the outlet side of the anode gas flow path 11 of the fuel cell 1 to the ejector 19.
The fuel gas supplied from the hydrogen tank 15 is supplied to the anode gas passage 11 of the fuel cell 1 through the fuel gas supply passage 17. The anode off gas is sucked into the ejector 19 through the anode circulation path 18, merges with the fuel gas supplied from the hydrogen tank 15, is supplied to the fuel cell 1 again, and is circulated.

An anode off-gas discharge pipe 22 is branched from the anode circulation path 18 via an electromagnetically driven purge valve 21. The purge valve 21 is periodically opened according to the operating state of the fuel cell 1 such as when the concentration of impurities (water, air, nitrogen, etc.) in the anode off-gas circulating through the fuel cell 1 becomes high. The anode off gas is discharged from the discharge pipe 22. A scavenging gas discharge pipe 22a is branched from the anode circulation path 18 via an electromagnetically driven scavenging gas discharge valve 21a.
The anode off gas and the scavenging gas contain unreacted fuel gas. Therefore, the anode off gas discharge pipe 22 and the scavenging gas discharge pipe 22 a are connected to the diluter 30. The diluter 30 dilutes the anode off-gas and the scavenging gas with the cathode off-gas and discharges it to the outside.

On the other hand, an oxidant gas supply path 8 is connected to the inlet side of the cathode gas flow path 12 of the fuel cell 1. The oxidant gas supply path 8 is provided with an air compressor 7 that supplies the oxidant gas and a humidifier (not shown) that humidifies the oxidant gas using the cathode off gas. A cathode offgas discharge pipe 9 is connected to the outlet side of the cathode gas passage 12. The cathode offgas discharge pipe 9 passes through the humidifier and is connected to the diluter 30 via the back pressure control valve 10. A bypass flow path 32 is branched from the oxidant gas supply path 8 and connected to the diluter 30. The bypass passage 32 is provided with a dilution ventilation valve (not shown) that switches the communication state of the bypass passage 32.
The air pressurized by the air compressor 7 is supplied to the cathode gas flow path 12 of the fuel cell 1 through the oxidant gas supply path 8. After this oxygen in the air is used as an oxidant for power generation, it is discharged from the fuel cell 1 as a cathode off gas.

Inside the fuel cell 1, a coolant channel 40 through which cooling water flows is provided. A coolant circulation path 41 is provided outside the fuel cell 1, and cooling water circulates through the coolant flow path 40 and the coolant circulation path 41. The refrigerant circulation path 41 is provided with a cooling water pump 42 that supplies cooling water to the refrigerant flow path 40. Further, the refrigerant circulation path 41 is provided with an FC radiator 44 that performs heat exchange of the cooling water discharged from the refrigerant flow path 40.
The fuel cell 1 generates heat with power generation, but is cooled by cooling water flowing through the refrigerant flow path 40. The cooling water discharged from the fuel cell 1 is supplied to the fuel cell 1 again by the cooling water pump 42 and circulated after heat exchange is performed by the FC radiator 44.

(Temperature sensor)
An anode gas temperature sensor (TH2STKOUT) T1 for detecting the temperature of the anode gas (anode off gas) is provided in the anode circulation path 18 near the outlet of the anode gas path 11. A cathode gas temperature sensor (TASTKOUT) T2 for detecting the temperature of the cathode gas (cathode offgas) is provided in the cathode offgas discharge pipe 9 near the outlet of the cathode gas passage 12. In addition, a coolant temperature sensor (TWSTKOUT) T3 for detecting the temperature of the coolant is provided in the coolant circulation path 41 near the outlet of the coolant channel 40.

(Scavenging gas supply means)
The fuel cell system 100 includes scavenging gas supply means for supplying a scavenging gas to the reaction gas flow path. Specifically, air is supplied from the air compressor 7 to the anode gas passage 11 and the cathode gas passage 12. In order to supply air to the anode gas passage 11, a scavenging gas introduction passage 24 is provided branched from the oxidant gas supply passage 8. The scavenging gas introduction path 24 is connected to the fuel gas supply path 17 via the scavenging gas introduction valve 23.

  The fuel cell system 100 also includes a controller 60 that controls the operation of each unit. The controller 60 functions as a first determination unit that determines whether or not the temperature of the fuel cell 1 is equal to or lower than a first predetermined temperature using the detection value of the anode gas temperature sensor T1. Further, the controller 60 functions as a temperature change rate detection unit that detects the temperature change rate using the detection value of the cooling water temperature sensor T3. Furthermore, the controller 60 functions as a second determination unit that determines whether or not the detected temperature change rate is equal to or lower than a predetermined temperature change rate. Details of these will be described later.

Further, the controller 60 functions as a scavenging control unit that scavenges the reaction gas flow path in a state where the power generation of the fuel cell 1 is stopped.
When scavenging the anode gas flow path 11, the controller 60 first closes the dilution ventilation valve, the fuel gas shutoff valve, the circulation shutoff valve, the purge valve 21 and the back pressure control valve 10, and the scavenging gas introduction valve 23 and the scavenging gas. The discharge valve 21a is opened. Next, the controller 60 operates the air compressor 7 to supply air as scavenging gas. The air supplied from the air compressor 7 does not flow into the cathode gas passage 12 because the back pressure control valve 10 is closed, and flows into the scavenging gas introduction passage 24 in which the scavenging gas introduction valve 23 is opened, Furthermore, since the scavenging gas discharge valve 21a is opened, it flows into the anode gas flow path 11. This scavenging gas is discharged from the scavenging gas discharge pipe 22a together with the generated water remaining in the anode gas flow path 11 and the generated water adhering to the anode electrode.

  When scavenging the cathode gas flow path 12, the controller 60 first closes the dilution ventilation valve, the fuel gas shutoff valve, the circulation shutoff valve, the scavenging gas introduction valve 23, the purge valve 21 and the scavenging gas discharge valve 21 a, and back pressure. The control valve 10 is opened. Next, the controller 60 operates the air compressor 7 to supply air as scavenging gas. The air supplied from the air compressor 7 does not flow into the scavenging gas introduction passage 24 because the scavenging gas introduction valve 23 is closed, and flows into the cathode gas passage 12 because the back pressure control valve 10 is opened. To do. This scavenging gas is discharged from the cathode offgas discharge pipe 9 along with the generated water remaining in the cathode gas flow path 12 and the generated water adhering to the cathode electrode.

(Scavenging method)
Next, a scavenging method for the fuel cell system will be described.
FIG. 2 is a flowchart of the scavenging method of the fuel cell system according to the present embodiment. The scavenging process is performed during the soak period of the fuel cell 1 (the period from when the fuel cell is stopped until it is next started). Therefore, the flowchart of FIG. 4 starts from a state in which the ignition switch is turned off.

First, in S10, the controller 60 starts RTC monitoring. Specifically, each temperature sensor is activated every predetermined time (for example, 5 minutes) to detect the temperature. Next, in S12, the anode gas temperature TH is detected by the anode gas temperature sensor T1 (anode gas temperature detection step). In S14, the cooling water temperature TW is detected by the cooling water temperature sensor T3 (cooling water temperature detection step). Next, in S16, the TW change rate is detected (cooling water temperature change rate detection step). Specifically, the difference between the TW detected this time and the TW detected last time is obtained.
Next, in S18, it is determined whether TH is equal to or lower than the first predetermined temperature, and it is determined whether the TW change rate is equal to or lower than the predetermined temperature change rate (determination step). If the determination in S18 is Yes (TH is equal to or lower than the first predetermined temperature and the TW change rate is equal to or lower than the predetermined temperature change rate), the process proceeds to S22 and the scavenging process is performed (scavenging process). .

  FIG. 3A is a graph of the change with time of the anode gas temperature (TH), and FIG. 3B is a graph of the change with time of the cooling water temperature (TW) change rate. In FIG. 3, the time when the ignition switch is turned off and the fuel cell is stopped is set to zero. As shown in FIG. 3A, the anode gas temperature TH, which is the detected value of the anode gas temperature sensor T1, decreases monotonously after the fuel cell 1 stops operating. The same applies to the cathode gas temperature TA, which is a detection value of the cathode gas temperature sensor T2, and the cooling water temperature TW, which is a detection value of the cooling water temperature sensor T3. Since TH, TA, and TW are proportional to the temperature of the fuel cell, the temperature of the fuel cell can be estimated using TH, TA, and TW.

  On the other hand, the TW change rate shown in FIG. 3B is proportional to the difference between the cooling water temperature TW and the outside air temperature. As described above, the TW decreases with the passage of time, so that the TW change rate also decreases with the passage of time as shown in FIG. When a long time elapses and the temperature of the fuel cell reaches a soaking state in which it approaches the outside air temperature, the TW change rate approaches zero.

By the way, the scavenging process needs to be performed before the fuel cell 1 becomes below freezing point. Therefore, for example, it is conceivable to perform the scavenging process when the temperature of the fuel cell becomes 10 ° C. or lower.
However, an offset failure may occur in the cooling water temperature sensor T3. For example, when an offset failure of + 5 ° C. occurs, the detected value of the cooling water temperature sensor T3 indicates 45 ° C. even though the actual cooling water temperature is 40 ° C. In this case, the temperature of the fuel cell is erroneously estimated, and it is difficult to perform the scavenging process at an appropriate timing.

Therefore, in the present embodiment, as shown in FIG. 3A, the temperature of the fuel cell 1 is set to the first predetermined temperature A1 (for example, 10 ° C.) using the anode gas temperature TH that is a detection value of the anode gas temperature sensor T1. It is determined whether or not: In addition, you may determine whether TH itself is below 1st predetermined temperature. As described above, by using the anode gas temperature TH that is the detection value of the anode gas temperature sensor T1, even when an offset failure occurs in the cooling water temperature sensor T3, scavenging is performed at an appropriate timing before the fuel cell 1 becomes below freezing point. Processing can be performed.
An offset failure may occur in the anode gas temperature sensor T1. In this case, the temperature of the fuel cell 1 may be estimated not only from TH but also from TA and TW, and the lowest value of the estimated temperatures may be compared with the first predetermined temperature.

In the present embodiment, as shown in FIG. 3B, it is determined whether or not the TW change rate is equal to or less than a predetermined temperature change rate D. Since the TW change rate is the difference between the TW detected this time and the TW detected last time, even if an offset failure occurs in the cooling water temperature sensor T3, the offset can be eliminated. Thereby, it is possible to accurately grasp that the fuel cell is in a soaking state regardless of the presence or absence of an offset failure.
When the fuel cell is in a soaking state, the water vapor in the fuel cell is fully condensed. By scavenging in this state, the generated water in the fuel cell can be efficiently discharged.

  Note that it is first determined whether or not the temperature of the fuel cell is equal to or lower than the first predetermined temperature (first determination step), and when it is determined that the temperature is equal to or lower than the first predetermined temperature, the TW change rate changes to the predetermined temperature. You may determine whether it is below a rate (2nd determination process). In this first determination step, when it is determined that the temperature of the fuel cell exceeds the first predetermined temperature, the second determination step and the scavenging step are not performed. When the temperature of the fuel cell 1 exceeds the first predetermined temperature, there is no possibility that the generated water will freeze in the fuel cell, so that wasteful energy consumption can be prevented by stopping the scavenging process.

Returning to FIG. 2, when the determination in S18 is No, the scavenging process is not performed. In this case, the process proceeds to S20, the TW is stored for detection of the next TW change rate, and the RTC monitoring in S20 is continued.
On the other hand, after the scavenging process is performed in S22, the process proceeds to S24 to stop the RTC monitoring, and all the processes are terminated.

FIG. 4 is a flowchart of a scavenging method for a fuel cell system according to a modification of the present embodiment. Detailed description of the same steps as those in this embodiment will be omitted.
In the above-described embodiment, even if TH is equal to or lower than a first predetermined temperature (for example, 10 ° C.), the scavenging process is not performed unless the TW change rate is equal to or lower than the predetermined temperature change rate. Therefore, when the outside air temperature is extremely low, there is a possibility that the TW change rate does not fall below the predetermined temperature change rate even when the fuel cell is below freezing point.

  Therefore, in this modification, after detecting the anode gas temperature TH in S12, it is determined in S13 whether TH is lower than a second predetermined temperature (for example, 5 ° C.). If the determination in S13 is Yes, the process proceeds to S22 and the scavenging process is immediately performed. As a result, even when the outside air temperature is extremely low and the TW change rate does not fall below the predetermined temperature change rate, the scavenging process can be performed at an appropriate timing before the fuel cell is below freezing point.

The present invention is not limited to the embodiment described above.
For example, although the anode gas temperature TH and the first predetermined temperature are compared in the embodiment, the cathode gas temperature TA and the first predetermined temperature may be compared, and the cooling water temperature TW and the first predetermined temperature may be compared. May be. Moreover, you may carry out combining these.
On the other hand, in the embodiment, the TW change rate and the predetermined temperature change rate are compared, but the TH change rate and the predetermined temperature change rate may be compared, or the TA change rate and the predetermined temperature change rate may be compared. . Moreover, you may carry out combining these. However, since the fluctuation range of the TW change rate is larger than the TH change rate and the TA change rate, the use of the TW change rate can improve the accuracy of comparison with the predetermined temperature change rate.
The fuel cell system shown in FIG. 1 is an example, and other configurations may be adopted.

1 is a block diagram showing a schematic configuration of a fuel cell system according to an embodiment. It is a flowchart of the scavenging method of the fuel cell system which concerns on embodiment. (A) is a graph of the change with time of the anode gas temperature, and FIG. 3 (b) is a graph of the change with time of the cooling water temperature change rate. It is a flowchart of the scavenging method of the fuel cell system which concerns on the modification of embodiment.

Explanation of symbols

  A1 ... first predetermined temperature A2 ... second predetermined temperature D ... predetermined temperature change rate S12 ... anode gas temperature detection step S14 ... cooling water temperature detection step S16 ... cooling water temperature change rate detection step S18 ... determination step S22 ... scavenging step T1 ... anode gas temperature sensor (reaction gas temperature detection means) T2 ... cathode gas temperature sensor (reaction gas temperature detection means) T3 ... cooling water temperature sensor (cooling fluid temperature detection means) TA ... cathode gas temperature TH ... anode gas temperature TW ... Cooling water temperature 1 ... Fuel cell 7 ... Air compressor (scavenging gas supply means) 40 ... Refrigerant flow path 60 ... Controller (scavenging control unit, temperature change rate detection means, first determination unit, second determination unit)

Claims (6)

A fuel cell that supplies the reaction gas to the reaction gas channel to generate power;
A cooling fluid supplied to a refrigerant flow path inside the fuel cell;
A scavenging gas supply means for supplying a scavenging gas to the reaction gas flow path;
A scavenging control unit for scavenging the inside of the fuel cell with the scavenging gas in a state where power generation of the fuel cell is stopped;
A fuel cell system comprising:
Reaction gas temperature detection means for detecting the temperature of the reaction gas;
Cooling fluid temperature detection means for detecting the temperature of the cooling fluid;
It is determined whether or not the temperature of the fuel cell is equal to or lower than a first predetermined temperature using one of the detection value of the reaction gas temperature detection means and the detection value of the cooling fluid temperature detection means. A first determination unit;
A temperature change rate detecting means for detecting a temperature change rate using the other detection value not used in the first determination unit;
Whether or not the temperature change rate detected by the temperature change rate detection means is less than or equal to a predetermined temperature change rate when the first determination unit determines that the temperature of the fuel cell is lower than or equal to the first predetermined temperature. A second determination unit for determining whether or not
Further comprising
The scavenging control unit performs scavenging when the second determination unit determines that the temperature change rate is equal to or less than the predetermined temperature change rate.   2. The fuel according to claim 1, wherein when the first determination unit determines that the temperature of the fuel cell exceeds the first predetermined temperature, the determination by the second determination unit is not performed. 3. Battery system.   The scavenging control unit performs scavenging when the first determination unit determines that the temperature of the fuel cell is equal to or lower than a second predetermined temperature lower than the first predetermined temperature. The fuel cell system according to claim 1 or 2. A fuel cell that supplies the reaction gas to the reaction gas channel to generate power;
A cooling fluid supplied to a refrigerant flow path inside the fuel cell;
A scavenging gas supply means for supplying a scavenging gas to the reaction gas flow path;
A scavenging control unit for scavenging the inside of the fuel cell with the scavenging gas in a state where power generation of the fuel cell is stopped;
Reaction gas temperature detection means for detecting the temperature of the reaction gas;
Cooling fluid temperature detection means for detecting the temperature of the cooling fluid;
A scavenging method for a fuel cell system comprising:
A reaction gas temperature detection step of detecting the temperature of the reaction gas by the reaction gas temperature detection means;
A cooling fluid temperature detection step of detecting a temperature of the cooling fluid by the cooling fluid temperature detection means;
It is determined whether or not the temperature of the fuel cell is equal to or lower than a first predetermined temperature by using one of the detection value of the reaction gas temperature detection step and the detection value of the cooling fluid temperature detection step. A first determination step;
A temperature change rate detection step of detecting a temperature change rate using the other detection value not used in the first determination step;
Whether or not the temperature change rate detected in the temperature change rate detection step is less than or equal to a predetermined temperature change rate when it is determined in the first determination step that the temperature of the fuel cell is lower than or equal to the first predetermined temperature. A second determination step for determining whether or not
A scavenging step of scavenging by the scavenging control unit when it is determined in the second determination step that the temperature change rate is equal to or less than the predetermined temperature change rate;
A scavenging method for a fuel cell system.   5. The fuel cell system according to claim 4, wherein in the first determination step, when it is determined that the temperature of the fuel cell exceeds the first predetermined temperature, the determination in the second determination step is not performed. Scavenging method.   5. The scavenging step is performed when it is determined in the first determination step that the temperature of the fuel cell is equal to or lower than a second predetermined temperature lower than the first predetermined temperature. Item 6. A scavenging method for a fuel cell system according to Item 5.

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