JP2003187846A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of shortening a start-up time, even if the air flow control means is frozen or fixed. <P>SOLUTION: There are provided a fuel cell body 12, which generates power from the reformed gas generated by a reformer 11 and the air supplied from an air supply means, a combustor 13 which catalytically combusts the gas exhausted from the fuel cell body 12 by receiving the air from the air supply means, and flow control valves 8-10 which control the flow rate of the air supplied to the reformer 11, the fuel cell body 12, and the combustor 13 by the air supply means, by changing the opening degree of a flow channel. To stop the power generation of the fuel cell body 12, the flow control valves 8-10 are closed immediately after power generation is stopped, and then the flow control valve 8-10 are opened, when a prescribed condition is established. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a vehicle fuel cell system.

[0002]

2. Description of the Related Art When a fuel cell system is left in a low temperature atmosphere of 0 ° C. or less in a stopped state and the air flow rate control means (valve) is frozen and stuck due to moisture contained in the air, the ice is melted at the time of startup. It is necessary to make the air flow rate control means movable. As a means for this, a method of raising the temperature of the system by a high temperature gas supplied by using a compressor or the like which is conventionally an air supply means (Japanese Patent Application Laid-Open No. 2000-2000)
(-12060, JP-A-5-131131)
Have been proposed.

[0003]

However, the method of thawing the air flow rate control means by raising the temperature of the system by the high temperature air supplied from the air supply means as in the above-mentioned conventional example is until melting of ice. Since it takes a long time, there was a problem that the system startup time becomes long.

Further, when the power generation is stopped normally, the air flow rate control means maintains the fully closed state.
Since the air supplied from the air supply means does not reach the device located downstream of the air flow rate control means, there is also a problem that the system startup time becomes longer.

In general, a method of melting ice by using a heater or an electric heater can be considered, but in this case, the system becomes complicated and it is necessary to use attached energy such as a battery.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell system capable of shortening the start-up time even when the air flow rate control means is frozen or stuck.

[0007]

The first invention is a fuel reforming means for producing a hydrogen-rich reformed gas through a reforming reaction of a raw fuel under a reforming catalyst, and the fuel reforming means. The power generation means for generating power from the reformed gas and the air supplied from the air supply means, the combustion means for catalytically burning the exhaust gas discharged from the power generation means by supplying the air from the air supply means, and the air supply means for changing the fuel. Air flow rate control means for controlling the flow rate of the air supplied to the quality means, the power generation means and the combustion means by changing the opening degree of the flow path, and when stopping the power generation of the power generation means, the air flow rate immediately after the power generation is stopped. And a power generation stop time control means for closing the control means and then opening the air flow rate control means when a predetermined condition is satisfied.

The second aspect of the invention is to supply the power generation means for generating power from the hydrogen gas supplied from the hydrogen storage means and the air supplied from the air supply means and the exhaust gas discharged from the power generation means from the air supply means. A combustion means for receiving the catalyst and performing catalytic combustion; an air flow rate control means for controlling the flow rate of the air supplied by the air supply means to the fuel reforming means, the power generation means and the combustion means by changing the opening of the flow path; When the power generation is stopped, the air flow control means is closed immediately after the power generation is stopped, and then the air flow control means is opened when a predetermined condition is satisfied.

A third invention is the first or second invention.
In the invention described above, the power generation stop control means determines that the predetermined condition is satisfied since the time until the temperature of the catalyst does not react decreases after the power generation is stopped.

The catalyst has at least one of fuel reforming means and combustion means.

A fourth invention is the first or second invention.
In the invention, the power generation stop time control means makes the valve closing period of the air flow rate control means longer as the power generation amount in the power generation means within a preset time immediately before the power generation stop is larger.

A fifth aspect of the present invention is the first or second aspect.
In the invention described above, the power generation stop control means has a detection means for detecting the temperature of at least one of the fuel reforming means and the combustion means, and it is predetermined that the temperature detected after the power generation stop has fallen to a predetermined value. As the condition is satisfied, the flow rate control means is opened.

Further, in a sixth aspect based on the fifth aspect, the predetermined condition is satisfied when the temperature detected by the temperature detecting means is a temperature at which the catalytic reaction of the fuel reforming means and the combustion means is stopped.

In a seventh aspect based on the fifth aspect, the temperature detecting means detects the temperature of the reforming catalyst of the fuel reforming means or the combustion catalyst of the combustion means.

In an eighth aspect based on the fifth aspect, the temperature detecting means estimates the temperature of the catalyst based on the temperature of air or combustion gas in the catalyst.

In a ninth aspect based on the fifth aspect, the temperature detecting means detects the temperature of the refrigerant in the heat exchanger of the catalyst and estimates the temperature of the catalyst based on the temperature of the refrigerant. .

In a tenth aspect based on the fifth aspect, the temperature detecting means detects the container temperature of the catalyst and estimates the temperature of the catalyst based on the detected temperature.

The eleventh aspect of the present invention is the power supply control means according to the first or second aspect, wherein the power generation stop control means requires an opening degree for opening the air flow rate control means after a predetermined condition is satisfied at system startup. It has an opening degree setting means for setting it according to a proper air flow rate.

In a twelfth aspect based on the eleventh aspect, the opening degree setting means controls the opening degree of the air flow rate control means to maintain the temperature at which the catalyst reacts and to generate electricity in an auxiliary machine of an automobile. Set it to a value that allows the flow rate of air required to generate the power required for driving.

In a thirteenth aspect of the present invention based on the eleventh or twelfth aspect, the opening degree setting means has an outside air temperature detecting means for detecting the outside air temperature, and the outside air temperature when power generation is stopped becomes lower. The opening degree of the air flow rate control means is set large.

In addition, in a fourteenth aspect based on the first or second aspect, the air flow rate control means maintains the opening degree set after the power generation is stopped when freeze is detected at the time of system startup. It has freeze detection means.

The fifteenth aspect of the invention is the fuel cell system according to the fourteenth aspect, wherein the air flow rate control means controls the opening degree when freezing is not detected at system startup or when the frozen state is resolved. Shift to control during normal operation.

The sixteenth aspect of the invention is the fuel cell system according to the fourteenth aspect, wherein the freeze detecting means has an opening degree detecting means for detecting an opening degree of the valve, and a command value to the air flow rate controlling means and an opening degree. Whether or not the air flow rate control means is frozen is detected by comparing the opening degree of the air flow rate control means detected by the degree detection means.

A seventeenth aspect of the invention is the fuel cell system according to the fourteenth aspect, wherein the freezing detection means has a current detection means for detecting a current supplied to the air flow rate control means. By comparing the command value with the current value detected by the current detection means, the presence or absence of freezing of the air flow rate control means is detected.

In addition, in an eighteenth invention based on the sixteenth or seventeenth invention, the freeze detecting means issues at least two different opening command values.

[0026]

Therefore, according to the first or second aspect of the invention, the air flow rate control means is closed immediately after the power generation is stopped, so that the supply of air to the fuel reforming means and the power generation means is cut off and the catalytic reaction is stopped. Will stop and the entire system can be stopped without fail.

After that, when a predetermined condition is satisfied, the air flow rate control means is opened, so that the air flow path is secured even if the flow rate control means freezes and sticks after the power generation is stopped. With this valve opening, the system can be started up in a short time at the next startup regardless of whether or not there is freezing.

Further, according to the third aspect of the present invention, the time required until the catalyst becomes unreacted, which is obtained in advance by an experiment or the like, is set, so that it is not necessary to increase the number of sensors and the like, and the apparatus can be configured simply.

Further, in the fourth aspect of the invention, when the amount of power generated by the power generation means is large, the temperature of the catalyst (fuel reforming means and combustion means) also becomes high, so the power generation means at a preset time immediately before the stop of power generation. When the power generation amount is large, the time until the air flow rate control means is opened is extended, so the air flow rate control means is opened while the temperature of the catalyst of the fuel reforming means and the combustion means is still reacting. Can be prevented.

Further, according to the fifth aspect of the invention, the air flow rate control means can be opened after the detected temperature of at least one of the fuel reforming means and the combustion means has dropped to a predetermined value. Can be controlled.

Further, in the sixth aspect of the invention, since the predetermined temperature for opening the air flow control means is the temperature at which the catalyst (fuel reforming means and combustion means) does not react, the air flow control means is opened. Even if air later flows in, the fuel cell system can be reliably stopped.

Further, in the seventh aspect of the invention, it is possible to determine whether the predetermined condition is satisfied by detecting the temperature of the reforming catalyst of the fuel reforming means or the combustion catalyst of the combustion means.

In the eighth aspect of the invention, the temperature of the reformed gas and the combustion gas in the fuel reforming means and the combustion means is directly detected, and the temperature of the catalyst is estimated from this temperature, so that the satisfaction of the predetermined condition can be determined. .

In the ninth aspect of the invention, it is possible to determine whether the predetermined condition is satisfied by detecting the refrigerant temperature of the heat exchanger of the catalyst such as the fuel reforming means and the combustion means. Particularly, since the refrigerant temperature is lower than the temperature of the catalyst, the temperature can be detected by a simple detecting means.

Further, in the tenth aspect of the invention, it is possible to determine whether or not the predetermined condition is satisfied by detecting the temperature of the container in the catalyst (fuel reforming means and combustion means). In particular, the temperature can be detected by a simple method without making a large change to the container body or the like in order to detect the temperature of the container surface.

According to the eleventh or twelfth aspect of the invention, when the air flow rate control means is opened after the above predetermined conditions are satisfied, the reaction of the catalysts of the fuel reforming means and the combustion means can be maintained, and the automobile By controlling the electric power required to drive each auxiliary device so that the opening degree allows the power generation means to generate power, the air flow rate control means freezes at the next system startup,
Since the flow path of the air supplied by the air supply means can be secured even when the air supply means is fixed, the fuel cell system can be reliably started up and the frozen flow rate control means can be thawed.

Further, in the thirteenth invention, since the opening degree of the air flow rate control means is set to be larger as the outside air temperature is lower when the system is stopped, even if the air flow rate control means is frozen at the next system startup, The system can be started in a short time, and the frozen air flow rate control means can be quickly dissolved.

In the fourteenth aspect of the present invention, the air flow rate control means has freeze detection means, and when freeze is detected at the time of start-up, the opening set after the last system stop is maintained, so that freeze or sticking is performed. It is possible to avoid forcibly moving the air flow rate control means.

Further, according to the fifteenth aspect, when the freezing of the air flow rate control means is thawed, the control returns to the control during normal operation, so that the fuel reforming means and the power generating means perform efficient reforming reaction and power generation. You can

In the sixteenth aspect of the invention, the air flow rate control means has an opening degree detection means, and the presence or absence of freezing can be confirmed by comparing the input opening degree command value with the opening degree at that time. I can.

In the seventeenth aspect of the invention, the air flow rate control means has a current detection means, and the presence or absence of freezing can be confirmed by comparing the input opening command value with the current at that time.

According to the eighteenth aspect of the present invention, since the command value of the freezing detecting means is detected by at least two different command values for one detection operation, the opening degree of the flow rate controlling means and the Even if the opening degree of one command value is the same, the freeze detection can be surely performed by the other command values.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

In FIG. 1, 1 is an air filter, 2 and 5-7 are air flow meters, 3 is a compressor, 4 is a compressor drive motor, 8-10 are flow control valves, 11 is a reformer, and 12 is a fuel cell main body. , 13 are combustors, and 14 are mufflers.

Further, in FIG. 1, the air filter 1 to the compressor drive motor 4 constitute an air supply means, and an air flow meter 5 and a flow rate control valve 8, an air flow meter 6 and a flow rate control valve 9, an air flow meter 7 and a flow rate control valve 10 are provided.
Respectively constitute the air flow rate control means.

A reformer (fuel reforming means) 11 for reforming raw fuel is provided downstream of the flow rate control valve 10. Downstream of the reformer 11 and the flow rate control valve 9 is a power generation means. A fuel cell body 12 is provided.

A combustor 13 as a combustion means is provided downstream of the fuel cell body 12 and the flow control valve 8.
The exhaust gas generated in the combustor 13 is released to the atmosphere via the muffler 14.

The air supply means controls the compressor drive motor 4 so that the discharge amount of the compressor 3 becomes a desired flow rate after the air flow meter 5 detects the flow rate of the air cleaned by the air filter 1. .

The air flow rate control means is provided in each of the flow paths to the reformer 11, the fuel cell main body 12, and the combustor 13, and is located at a desired downstream from the flow rates detected by the air flow meters 5, 6, and 7. Flow control valves 8, 9
The opening of 10 is changed, the reformer 11, the fuel cell main body 12,
The flow rate of air supplied to the combustor 13 is controlled.

The reformer 11 is a hydrocarbon fuel (raw fuel) such as methanol or gasoline from a tank (not shown) or the like.
A reforming reaction is caused in the reforming catalyst by using water and air supplied from the air and air supply means to generate a mixed gas of H ₂ and CO. Since CO poisons the platinum electrode of the fuel cell body 12 and significantly deteriorates the performance of the fuel cell body, the reformer 11 uses C in the mixed gas by means such as selective oxidation reaction.
It is also equipped with a device for removing O and generating a hydrogen-rich reformed gas.

The fuel cell main body 12 is supplied with the reformed gas generated in the reformer 11 to the fuel electrode and reacts with the air supplied from the air supply means to generate electricity.

The combustor 13 oxidizes the reformed reformed gas discharged from the fuel cell main body 12 and air with a catalyst and converts it into a substance such as water vapor that can be released into the atmosphere.

The flow control valves 8-10 are controlled by the control unit 100. The control unit 100 includes an outside air temperature detected by the temperature sensor 200, a combustor temperature detected by the temperature sensor 201, and a temperature sensor 2
02, the temperature of the reformer 11, the air flow rate detected by the air flow meters 2, 5, 6, and 7, the fuel cell body 12
The opening degree of each of the flow rate control valves 8, 9, 10 is determined based on the power generation amount of 1) and driven.

The flow chart of FIG. 2 shows an example of the flow rate control valve control performed by the control unit 100,
It is executed when the fuel cell system is stopped.

First, in step S1, the power generation stop signal is input to start the power generation stop processing.

In step S2, the flow rate control valves 8, 9 and 10 are closed to stop the respective reactions by stopping the air supply to the reformer 11, the fuel cell 12 and the combustor 13.

Next, in step S3, it is determined whether or not the temperatures of the catalysts of the reformer 11 and the combustor 13 have reached a non-reacting state (a predetermined condition is satisfied).

To detect the temperature at which the reaction of the catalyst is stopped, the temperatures detected by the temperature sensors 201 and 202 can be used. If the temperatures detected by the temperature sensors 201 and 202 are below a predetermined value, respectively. It is determined that the catalytic reaction has stopped, and the process proceeds to step S4.

The judgment of the termination of the catalytic reaction may be made based on the value detected or estimated indirectly, in addition to the method of directly detecting the temperature of the catalyst as described above.

For example, in FIG.
Or the time t until the catalyst of the combustor 13 stops the reaction
It shows the relationship between o and the catalyst temperature. The elapsed time to that can be equal to or lower than the temperature To at which the catalyst does not react is calculated from this graph or the like based on the detected temperatures of the reformer 11 and the combustor 13. In this case, in step S3, the elapse of time to is monitored by a timer or the like, and when this elapsed time to elapses, it is considered that the catalytic reaction has stopped, and the process proceeds to step S4.

Alternatively, FIG. 4 shows the relationship between the power generation amount W in the fuel cell main body 12 and the catalyst temperatures of the reformer 11 and the combustor 13 within a predetermined time immediately before the stop of power generation.

In this case, the detected fuel cell body 12
The catalyst temperature To is determined from the power generation amount W of the above, and the time to corresponding to the catalyst temperature To is obtained from the graph of FIG.
In 3, monitor the time to elapse with a timer etc.,
When this elapsed time to has elapsed, it is considered that the catalytic reaction has stopped, and the process proceeds to step S4. This allows
The control can be performed without directly detecting the temperatures of the reformer 11 and the combustor 13. The larger the amount of power generation within the preset time immediately before the stop of power generation, the longer the period (time) for closing the flow control valve and waiting for the stop of the catalytic reaction.

Besides, the temperature sensor 202 detects the temperature of the reformed gas in the reformer 11, and the temperature sensor 201 detects the temperature of the combustor 1.
The temperature of the combustion gas in 3 may be detected. In this case, the detected temperature Tg of each gas as shown in FIG.
And the catalyst temperature To are used to estimate the catalyst temperature.
Then, when the detected gas temperature Tg reaches the temperature To at which the catalytic reaction stops, the process can proceed to step S4.

Alternatively, the same determination can be made by estimating the temperature of the catalyst from the temperature of the refrigerant of the heat exchanger that cools the reformer 11 and the combustor 13.

Next, in step S4, the temperature sensor (outside air temperature detecting means) 200 detects the outside air temperature when power generation is stopped, and the outside air temperature detected in step S5 is necessary for the reformer 11 and the combustion when the system is started. The openings of the flow rate control valves 8, 9 and 10 are determined so as to maintain the temperature at which the catalyst of the vessel 13 reacts and to obtain the air flow rate required to generate the electric power required to drive the auxiliary equipment of the automobile in the fuel cell main body 12. .

The air flow rate required for system startup becomes larger as the outside air temperature is lower, and the relationship between the outside air temperature and the flow control valve opening is as shown in the map of FIG. 6, and the outside air temperature is low. The opening of the flow control valve is 10
It becomes 0% (fully open), and the opening degree of the flow control valve approaches 0% (fully closed) as the outside air temperature rises. However, the valve is not fully closed for the next startup, and the predetermined opening is regulated as the minimum opening as shown in FIG.

Then, in step S6, the flow rate control valves 8, 9 and 10 are opened to the opening degrees determined in step S5, and the power generation stop processing ends. The opening degree of the flow rate control valves 8, 9 and 10 opened in step S6 may be a constant value regardless of the outside air temperature. When the control power supply of the entire system is forcibly shut off, the flow rate control valves 8, 9, 10 are mechanically opened.

By the above power generation stop processing, the flow control valves 8, 9 and 10 are closed to stop the power generation, and the reformer 1 is closed.
1 or the catalytic reaction of the combustor 13 is stopped. And
When it is determined that the catalytic reaction has stopped based on the temperature of each catalyst detected directly or indirectly, the flow rate control valves 8, 9, 10 are opened at an opening degree according to the outside air temperature when the power generation is stopped. .

Therefore, since each flow rate control valve is opened during the power generation stop period, even if the flow rate control valve freezes and sticks after the power generation stop due to a low outside air temperature, etc. Since the flow path of is secured, the system can be started up in a short time at the next start-up, and unlike the conventional example, the time for melting ice is not required, and the start-up time of the fuel cell system can be reduced. It can be shortened.

Next, FIG. 7 shows a flowchart when the system is started.

First, in step S11, the compressor 3, which is an air supply means, is activated to supply high temperature and high pressure air to the flow path.

In steps S12 and S13, freezing and sticking of the air flow control valves 8, 9 and 10 are detected. The air flow control valves 8, 9 and 10 each have an opening sensor (opening detection means) or a current sensor (current detection means) and are frozen or stuck depending on whether or not to respond to a drive command from the control unit 100. Detect the presence or absence.

That is, the control unit 100
Is a command value having at least two types of A1 and A2 having different values (opening) as shown in FIG.
Send to 9, 10.

Then, in response to these opening command values, one or more appropriate outputs (responses) from the opening sensor of each flow control valve.
Judgment of freezing and sticking is made depending on whether there is any. In the absence of one or more suitable outputs, these flow control valves 8,
It is determined that Nos. 9 and 10 are frozen or stuck, and the process proceeds to step S14, and the current opening (set value when power generation is stopped)
The air supplied from the compressor 3 is kept flowing while maintaining the above condition, and the reformer 11, the fuel cell main body 12, and the combustor 13 are continuously prepared for operation, and at the same time, the supplied hot air causes the flow control valves 8, 9, 10 to flow. Thaw the freeze. And
After a lapse of a predetermined time, the process returns to step S12 again, the freezing and sticking detection operation of the flow rate control valves 8, 9, 10 is performed, and the same determination as above is performed.

In step S14, if a proper output is not obtained as a result of repeating the detection a predetermined number of times, it is judged that the flow control valves 8, 9, 10 have failed.

On the other hand, in step S13, if there is at least one appropriate output from the opening sensor of each flow control valve, the flow control valves 8, 9, 10 are not frozen or have been melted. Then, the process proceeds to step S15 to start the control during normal operation.

When freezing is detected by a current sensor, freezing or sticking may be detected when the current of each flow control valve exceeds a predetermined value with respect to the opening command values A1 and A2. .

As described above, at the time of starting the fuel cell system, it is detected whether or not the flow rate control valves 8, 9, 10 are frozen or stuck, and if they are frozen or stuck,
It can be started at an opening degree according to the outside air temperature set when power generation is stopped, and high-temperature and high-pressure air can be supplied to each flow rate control valve 8, 9, 10 at this opening degree to promote melting of ice. As shown in the example, it is possible to shorten the time required for start-up as compared with the case where the system is started after freezing or sticking is eliminated.

Further, since the flow rate control valves 8, 9 and 10 are opened according to the outside air temperature when the power generation is stopped, the fuel cell system can be surely immediately started even if it is frozen. As a result, the operation of the vehicle can be started, and the practicality of the vehicle equipped with the fuel cell system can be improved.

FIG. 9 shows a case where the present invention is applied to another fuel cell system. While the reformer 11 is deleted,
A hydrogen cylinder 15 is provided, and the flow rate control valve 10 controls the flow rate of hydrogen.

In this case, since the catalytic combustion is performed only in the combustor 13, the flow control valves 8, 9 and 10 which are determined when the power generation is stopped wait for the catalytic reaction of the combustor 13 to stop, and the outside air temperature. It is only necessary to open the opening degree to a certain value or a fixed value, and the same effect as the above can be obtained.

The graphs of FIGS. 3 to 5 may be set in advance by experiments or the like and stored in the control unit 100 in advance as a map or a table.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fuel cell system showing an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a power generation stop process performed by a control unit.

FIG. 3 is a graph showing the relationship between the time taken to stop the catalytic reaction and the temperature of the catalyst when the power generation was stopped.

FIG. 4 is a graph showing the relationship between the amount of power generation and the catalyst temperature immediately before the stop of power generation.

FIG. 5 is a graph showing the relationship between gas temperature and catalyst temperature.

FIG. 6 is a map showing the opening of the flow control valve according to the outside air temperature.

FIG. 7 is a flowchart showing an example of a startup process performed by the control unit.

FIG. 8 shows a drive pattern for detecting freezing or sticking of a flow control valve, and shows a relationship between time and opening.

FIG. 9 is a schematic configuration diagram showing another form of a fuel cell system.

[Explanation of symbols]

1 Air filter 2 Air flow meter 3 compressor 4 Compressor drive motor 5-7 Air flow meter 8-10 flow control valve 11 reformer 12 Fuel cell body 13 Combustor 14 Muffler (silencer) 100 control unit 200-202 Temperature sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/00 H01M 8/00 ZF term (reference) 3D035 AA03 BA01 5H027 AA02 BA01 BA13 BA16 BC12 DD00 KK42 KK48 MM02 MM12

Claims (18)

[Claims] 1. A fuel reforming means for producing a hydrogen-rich reformed gas by a reforming reaction under a reforming catalyst, and a reformed gas produced by the fuel reforming means and an air supply means. Power generation means for generating power from air, combustion means for catalytically burning the exhaust gas discharged from the power generation means by supplying air from the air supply means, and air supply means for supplying fuel reforming means, power generation means and combustion means And an air flow rate control means for controlling the flow rate of the air by changing the opening of the flow path, and when stopping the power generation of the power generation means, the air flow rate control means is closed immediately after the power generation is stopped, and then a predetermined A fuel cell system comprising: a power generation stop control means for opening the air flow rate control means when a condition is satisfied. 2. A power generation means for generating power from hydrogen gas supplied from the hydrogen storage means and air supplied from the air supply means, and exhaust gas discharged from the power generation means is catalytically burned by receiving air supply from the air supply means. A combustion means, an air flow rate control means for controlling the flow rate of the air supplied by the air supply means to the fuel reforming means, the power generation means and the combustion means by changing the opening of the flow path, The fuel cell system further comprises a power generation stop time control unit that closes the air flow rate control unit immediately after the power generation is stopped and then opens the air flow rate control unit when a predetermined condition is satisfied. 3. The power generation stop control means determines whether or not a predetermined condition is satisfied, since the time until the temperature at which the catalyst does not react decreases after the power generation is stopped. 2. The fuel cell system according to item 2. 4. The power generation stop control means makes the valve closing period of the air flow rate control means longer as the amount of power generation in the power generation means within a preset time immediately before power generation stop is larger. Item 3. The fuel cell system according to Item 1 or 2. 5. The power generation stop control means has a detection means for detecting the temperature of at least one of the fuel reforming means and the combustion means, and the temperature detected after the power generation stop has fallen to a predetermined value. 3. The fuel cell system according to claim 1, wherein the flow rate control means is opened when the predetermined condition is satisfied. 6. The fuel cell system according to claim 5, wherein the predetermined condition is satisfied when the temperature detected by the temperature detecting means is a temperature at which the catalytic reaction stops. 7. The fuel cell system according to claim 5, wherein the temperature detecting means detects the temperature of the reforming catalyst of the fuel reforming means or the combustion catalyst of the combustion means. 8. The fuel cell system according to claim 5, wherein the temperature detecting means estimates the temperature of the catalyst based on the temperature of air or combustion gas in the catalyst. 9. The fuel cell according to claim 5, wherein the temperature detecting means detects the temperature of the refrigerant in the heat exchanger of the catalyst and estimates the temperature of the catalyst based on the temperature of the refrigerant. system. 10. The fuel cell system according to claim 5, wherein the temperature detecting means detects the container temperature of the catalyst and estimates the temperature of the catalyst based on the detected temperature. 11. The power generation stop control means has an opening degree setting means for setting an opening degree for opening the air flow rate control means in accordance with an air flow rate required at system startup after a predetermined condition is satisfied. The fuel cell system according to claim 1 or 2, which is characterized. 12. The opening degree setting means sets a value of the opening degree of the air flow rate control means such that an air flow rate required for maintaining a temperature at which the catalyst reacts and for generating electric power required for driving an auxiliary machine of an automobile in the power generation means is set. 12. It is set to
The fuel cell system according to 1. 13. The opening degree setting means has an outside air temperature detecting means for detecting an outside air temperature, and the opening degree of the air flow rate controlling means is set to be larger as the outside air temperature at the time of power generation stop is lower. The fuel cell system according to claim 11 or 12. 14. The air flow rate control means according to claim 1, further comprising freezing detection means for maintaining the opening degree set after the power generation is stopped when freezing is detected at the time of system startup. The fuel cell system described. 15. The air flow rate control means shifts control of the opening degree to control during normal operation when freezing is not detected at system startup or when the freezing state is resolved. The fuel cell system according to claim 14. 16. The freeze detecting means has an opening detecting means for detecting an opening of a valve, and a command value to the air flow controlling means and an opening of the air flow controlling means detected by the opening detecting means. 15. The fuel cell system according to claim 14, wherein the presence or absence of freezing of the air flow rate control means is detected by comparing the degrees. 17. The freezing detection means has a current detection means for detecting a current supplied to the air flow rate control means, and a command value to the air flow rate control means and a current value detected by the current detection means. The presence / absence of freezing of the air flow rate control means is detected by comparing with.
4. The fuel cell system according to item 4. 18. The fuel cell system according to claim 16, wherein the freezing detection means issues at least two different opening instruction values.