JP2001313055A - Fuel cell device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent accumulation of hydrogen gas in a fuel cell main body after operation stop. In a direct water injection type fuel cell device, when the fuel cell device is stopped, after the water supply device is stopped, the air supply fan is stopped to remove moisture from the air chamber of the fuel cell body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fuel cell device, and more particularly, to a stop control thereof. The present invention
For example, it is suitable for a so-called PEM type fuel cell device having a polymer solid electrolyte membrane.

[0002]

2. Description of the Related Art A fuel cell body of a fuel cell device has a fuel electrode (also referred to as a hydrogen electrode when hydrogen is used as a fuel gas) and an oxidation electrode (generally, oxygen in the air is an oxidizing gas (reactive gas). (Also referred to as an oxygen electrode and also referred to as an air electrode).

[0003] The electrolyte of the fuel cell body must contain a sufficient amount of moisture since it allows protons to permeate during the power generation reaction. However, when the temperature of the fuel cell rises, moisture in the electrolyte is released, the resistance of the electrolyte increases, and operation becomes impossible. As a method for suitably maintaining the water content in the electrolyte, the applicant has proposed a so-called water direct injection type fuel cell device (Japanese Patent Application No. 10-378161).
No., applicant reference number: EQ97083-2, agent reference number: P0
6703). In this fuel cell device, a large amount of water is sprayed directly to the oxidation electrode side in a liquid state.

[0004]

The inventors of the present invention have made further studies on such a type of fuel cell device, and have found the following problems. Since a large amount of water is supplied to the oxidizing electrode side in the water direct injection type fuel cell device, a large amount of water remains in the oxidizing gas chamber (air flow path) of the fuel cell body even when this is stopped. I have. On the other hand, even if the supply of the fuel gas (reactive gas) is stopped to stop the fuel cell device, it is impossible to immediately stop the reaction in the electrolyte of the fuel cell main body. Continues the state where voltage is applied. When water is present in the fuel cell body while a voltage is applied between the oxidation electrode and the fuel electrode, the water is electrolyzed by the voltage and hydrogen gas is introduced into the oxidation gas chamber of the fuel cell body. May accumulate. This hydrogen gas can be exhausted by oxidizing gas (air) supplied at the start of operation, but it is preferable to prevent the generation of hydrogen gas in the fuel cell body beforehand.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has the following structure. That is,
A fuel cell body including an electrolyte and a fuel electrode and an oxidation electrode arranged to sandwich the electrolyte, an oxidizing gas supply device that supplies an oxidizing gas to an oxidizing gas chamber of the fuel cell body,
A fuel cell device comprising: a fuel gas supply device that supplies a fuel gas to a fuel gas chamber of the fuel cell body; and a water supply device that supplies water to the oxidizing gas chamber in a liquid state. The fuel cell device according to claim 1, wherein when the fuel cell device is stopped, the oxidizing gas supply device is stopped after the water supply device is stopped.

According to the fuel cell device configured as described above, even when water supplied from the water supply device is present in the oxidizing gas chamber when the fuel cell device is stopped, the supply of the oxidizing gas to the water is stopped. By supplying the water later, the water can be evaporated and / or moved to the water condenser, and then discharged out of the fuel cell main body. This can prevent the generation of hydrogen due to the electrolysis of water in the fuel cell body. In a fuel cell device of the type in which water is sprayed directly into the oxidizing gas chamber to control the wet state of the electrolyte in the fuel cell body, a large amount of water remains in the oxidizing gas chamber after the fuel cell device is stopped. Therefore, it is particularly preferable to remove the water by applying the present invention. However, the present invention relates to a fuel cell device of a type in which steam or mist is introduced into an oxidizing gas flow (air flow) to prevent excessive drying of an electrolyte. This does not preclude the application of. Claim 22 of the original specification considers the latter type of fuel cell device. Further, as in the invention described in claim 23 of the original specification, it is anticipated that water remaining in the fuel cell body will be electrolyzed to generate hydrogen, and this hydrogen is periodically removed from the fuel cell body. Can be discharged to the outside. For example, after stopping of the fuel cell device, 0.1 to 0.5 every 2.0 hours.
The blowing device as the oxidizing gas supply device is driven for 5.0 minutes to flow the oxidizing gas (air) into the oxidizing gas chamber (air chamber) of the fuel cell body. Thereby, even if hydrogen is generated, this hydrogen is surely discharged out of the system.

In order to reliably remove water remaining in the fuel cell body and prevent its electrolysis and hydrogen generation, the supply of water is stopped when the fuel cell device is stopped, and then a predetermined air volume is applied. The supply of the oxidizing gas is continued for a predetermined time. For example, the supply of the oxidizing gas is continued for 5 minutes or more. More preferably, it lasts 10 minutes or more. At this time, the supply mode of the oxidizing gas may be the same as before the shutdown of the fuel cell device, but in order to further ensure the removal of water, the supply amount of the oxidizing gas per unit time is increased. It is assumed that the supplied oxidizing gas passes through the oxidizing gas chamber and is discharged out of the system of the fuel cell device. It is desirable that the water evaporated in the oxidizing gas be recovered by a recovery device such as a water condenser and reused.

In one aspect of the present invention, the supply of the oxidizing gas is stopped after confirming that the moisture in the oxidizing gas chamber of the fuel cell body has been substantially removed or the moisture has been substantially dried. Let it. Therefore, a detection device (detection means) for detecting the state of the fuel cell main body is provided. The first type of detection device detects the voltage of the fuel cell main body after stopping the fuel cell device. When the detected voltage becomes equal to or less than a predetermined value, it is determined that the electrolysis of water has substantially disappeared, and the supply of the oxidizing gas is stopped. FIG. 1 shows the time course of the voltage of a single cell (one fuel cell main body) from when the fuel cell device was stopped except for the blower fan and when all functions including the blower fan were stopped (0 hour). Indicates a change. In the case of the fan-off, the voltage temporarily drops immediately after stopping the fuel cell device. This is considered to be due to electricity flowing into water (directly supplied to the air chamber (oxidizing gas chamber)) existing in the fuel cell device. That is, immediately after stopping the fuel cell device, if a large amount of water exists in the device,
In addition to the electrolyte membrane, an electric path is formed between the oxidation electrode and the fuel electrode via the water. When electricity flows through this path, water is decomposed there and hydrogen is generated. The peak of this electrolysis was 5
The electrolysis is no longer observed after 10 minutes. This is because the water that formed the electrical path between the oxidizing electrode and the fuel electrode disappeared (drops due to gravity, drying,
Due to electrolysis). On the other hand, when the fan is continuously rotated, such a decrease in voltage is not observed, and it is considered that electrolysis of water hardly occurs. Therefore, it is preferable that the fan be continuously rotated for 5 minutes or more after the fuel cell is stopped, that is, after the supply of water is stopped. More preferably, it is 10 minutes or more. More preferably, it is 15 minutes or more. The reason why the high voltage is maintained for a while after the fuel cell device is stopped is that protons are present in the electrolyte membrane, and the voltage gradually decreases as the protons are consumed. In terms of promoting the voltage drop, it is preferable to drive the blower fan for 20 minutes or more after the fuel cell device is stopped (at least after the fuel gas is stopped). More preferably, it is 35 minutes or more.

The second type of detecting device detects the concentration of hydrogen in the oxidizing gas discharged from the fuel cell body after stopping the fuel cell device. When the hydrogen concentration in the exhaust gas becomes equal to or less than a predetermined value, it is determined that the electrolysis of water has substantially disappeared, and the supply of the oxidizing gas is stopped. The third type of detection device directly or indirectly detects the temperature of the fuel cell body after stopping the fuel cell device. For example, the temperature of the fuel cell main body is indirectly detected by detecting the temperature of the oxidizing gas discharged from the fuel cell main body. Hydrogen generated by electrolysis of water in the oxidizing gas chamber easily enters at least the catalyst layer of the oxidizing electrode in the electrolyte. On the other hand, since water and oxygen are present in the electrolyte, it is considered that the electrolyte reacts with the generated hydrogen to generate heat. Therefore, if the temperature of the fuel cell body is monitored and the temperature falls below a predetermined value, it is determined that the electrolysis of water has been substantially eliminated,
Stop supplying the oxidizing gas. After stopping the fuel cell device, the fourth type of detection device detects the humidity (water vapor amount) in the exhaust gas of the fuel cell body or in the air chamber of the fuel cell body. If the humidity falls below a predetermined value, it is determined that the water has been sufficiently removed from the fuel cell body, and the supply of the oxidizing gas is stopped. The fifth type of detection device detects the amount of water recovered from the oxidizing gas discharged from the fuel cell main body after stopping the fuel cell device. For example, when the amount of water collected per unit time becomes equal to or less than a predetermined value, it is determined that the water has been sufficiently removed from the fuel cell body, and the supply of the oxidizing gas is stopped. Alternatively, since the water supply system is a closed system, when the water level in the water tank reaches a predetermined value, it is determined that sufficient water has been recovered from the fuel cell main body, and the supply of the oxidizing gas is stopped. The supply control of the oxidizing gas, that is, the forced drying control of at least the oxidizing gas chamber of the fuel cell body can be performed by using two or more of the first to fifth types of detecting devices in combination.

Hereinafter, each element of the present invention will be described. As means for efficiently using the latent heat of water, the particle diameter of water supplied to the oxidizing gas chamber is 50 μm to 500 μm.
It is preferable that It is desirable that the thickness of the electrolyte membrane of the fuel cell body be 20 μm to 200 μm. As a result of using the latent heat of water efficiently, the cooling plate can be thinned out or omitted from the stack of the fuel cell body. It is preferable to provide a cooling plate, a cooling pipe, or another cooling device in the stack of the fuel cell main body in consideration of a case where evaporation of a sufficient amount of water may not be ensured.
The heat of the stack is taken out to the outside by a heat medium (usually water) flowing to such a cooling device and can be used for heating the interior of the vehicle (so-called cogeneration). In the water direct injection type fuel cell device to which the present invention is suitably applied, the operation state of the fuel cell device is always controlled by controlling at least one of the amount of supplied water and the amount of supplied oxidizing gas (blowing amount). It is preferable to keep good. When controlling both, it is preferable to control each independently. The supply amount of water and / or the supply amount of oxidizing gas (blowing amount) can be controlled based on the temperature, output, exhaust gas component, and the like of the fuel cell device. In a water injection type fuel cell device, a sufficient amount of water is always supplied to the oxidizing gas chamber. That is, it is assumed that liquid water is always present in the oxidizing gas chamber during the operation of the fuel cell device, even if there is one that evaporates due to the heat of the fuel cell body. In the above, the oxidizing gas is supplied to the oxidizing electrode without being substantially compressed. The present invention can also be applied to a fuel cell device of a type having a pressurized oxidizing gas supply system. The pressurized oxidizing gas supply system includes not only the case where the oxidizing gas supply system is provided with the oxidizing gas compressor but also the case where the pressure inside the system becomes higher than the atmospheric pressure due to the resistance of the gas pipe. The temperature of the fuel cell body can of course be measured by attaching a thermometer to the fuel cell body, but the temperature can also be measured indirectly by measuring the temperature of the oxidized gas discharged. It is. In this case, it is preferable to measure the temperature of the oxidizing gas immediately after being discharged from the fuel cell body. The operating state of the fuel cell body is detected based on these temperatures. The thermometer serves as the operating condition detecting means.

[0011]

Next, embodiments of the present invention will be described. FIG. 2 shows a schematic configuration of the fuel cell device 1 of the embodiment.
As shown in FIG. 2, the apparatus 1 includes a stack of a fuel cell body 10, a hydrogen gas supply system 20 for supplying hydrogen gas as a fuel gas, an air supply system 40 for supplying air as an oxidizing gas, and a water supply system 50. , An output system 70.

FIG. 3 shows a schematic configuration of a unit of the fuel cell main body 10. The unit of the fuel cell body 10 has a configuration in which a solid polymer electrolyte membrane 12 is sandwiched between an air electrode 11 and a fuel electrode 13. In an actual device, a plurality of these unit units are stacked to form a fuel cell stack. FIG.
As shown in the figure, the air electrode 11-the solid polymer electrolyte membrane 1
2- The unit unit of the fuel electrode 13 has a thin plate shape and is sandwiched between a pair of carbon connector plates 16 and 17. A plurality of grooves 18 for circulating air are formed on the surface of the connector plate 16 facing the air electrode 11. Each groove 18 is formed in the up-down direction so that the manifold 14 and the first
Is connected to the duct 43 of FIG. As a result, the atomized water supplied from the nozzle 51 flows along the groove 18 along the air electrode 11.
To the lower part of. The peripheral surface of the groove 18 and the air electrode 1
An air chamber (oxidizing gas chamber) A is constituted by the exposed surface 1. The upper opening in the figure of the air chamber A is an air inlet (upstream opening), and the lower opening in the figure is an air outlet (downstream opening). It is preferable to provide a thermometer so as to detect the exhaust gas temperature at the outlet. In the embodiment, the liquid such as water is ejected directly to the upstream opening and supplied. However, the liquid such as water can be supplied from the downstream opening. Furthermore, a through-hole in the left-right direction in the figure can be formed in the connector plate, and a liquid such as water can be supplied to the air chamber A from this. The water supplied in this manner evaporates exclusively on the surface constituting the air chamber A (the peripheral surface of the groove 18 and the exposed surface of the air electrode 11: these are likely to be relatively hot). Similarly, the connector plate 17 facing the anode 13
Is formed with a groove 19 for flowing hydrogen gas. In the embodiment, a plurality of the grooves 19 are formed in the horizontal direction. A fuel chamber (oxidizing gas chamber) B is formed by the peripheral surface of the groove 19 and the exposed surface of the connector plate 17. Water can be supplied to the fuel chamber B in the same manner as in the air chamber A described above.

Since the air electrode 11 is supplied with water, it is formed of a water-resistant material. Further, if a water film is formed thereon, the effective area of the air electrode 11 is reduced.
Material 1 is also required to have high water repellency. As such a material, a gas diffusion layer in which (C + PTFE) was applied using carbon cloth as a base material was used. Solid polymer electrolyte membrane 1
A thin film of general-purpose Nafion (trade name: DuPont) was used for 2. The thickness of the membrane is not particularly limited as long as it allows reverse osmosis of the generated water from the air electrode side, and is, for example, 20 to 200 μm. The fuel electrode 13 has the same structure as the air electrode 11. The structure between the fuel electrode 13 and the air electrode 11 may be changed.

On the side of the air electrode 11 and the fuel electrode 13 which is in contact with the electrolyte membrane 12, a well-known platinum-based catalyst used to promote the reaction between oxygen and hydrogen with a certain thickness is uniformly applied. Dispersed in the air electrode 1
1 and a catalyst layer in the fuel electrode 13.

A plurality of water injection nozzles 51 are attached to the manifold 14 formed above the air chamber A. Water is directly injected from the nozzle 51 toward the upstream opening of the air chamber A. Most of the water directly sprayed toward the upstream opening of the air chamber A once adheres to the peripheral surface of the air chamber A, removes heat therefrom and evaporates (cooling by latent heat). The evaporation of water controls the evaporation of water from the electrolyte. Water adhering to the peripheral wall of the air chamber A moves downstream due to gravity and air flow. The mounting position of the water injection nozzle 51 in the manifold 14 is not particularly limited, but it is assumed that the water injected from the nozzle 51 uniformly spreads to the air chamber A of each fuel cell main body 10 constituting the stack.

It is preferable that the nozzle 51 directly sprays water toward the upstream opening of the air chamber A. Thus, a desired amount of water can be supplied to the air electrode side regardless of the air supply amount. That is, the supply amount of air and the supply amount of water can be controlled independently (independent supply type). According to the independent supply type, a desired amount of water can be reliably supplied to the air electrode side even in a state of a large air supply amount (air volume) such as at the time of startup. Therefore, the start-up time can be reduced. In a type in which water droplets are discharged into an air flow and supplied to the air electrode side while being placed on the air flow, the air supply amount and the water supply amount cannot be independently controlled (non-independent supply type). The change in the air supply and the change in the water supply are not always required at the same time, and may need to be changed independently. For example, when only the supply amount of air needs to be changed, if the supply amount of water is also changed, the response of control of the fuel cell main body becomes slow, which may lead to a decrease in output of the fuel cell device. . On the other hand, in the independent supply type employed in this embodiment, a required amount of water and / or air can be supplied at a required timing, so that the fuel cell main body can be efficiently controlled. Further, by independently controlling the supply of water and air, it is possible to avoid supply of useless air and useless water. Also in this respect, the operation of the fuel cell main body becomes efficient. Furthermore, the capacity of the condenser can be reduced by avoiding the supply of waste water and waste air.

As a hydrogen supply source of the hydrogen gas supply system 20,
In this embodiment, a hydrogen cylinder containing the hydrogen storage alloy 21 is used. In addition, a reforming reaction of a reforming raw material such as a hydrogen cylinder of liquid hydrogen or a water / methanol mixture is performed in a reformer to generate a hydrogen-rich reformed gas, and the reformed gas is stored in a tank. This can be used as a hydrogen source.
When the fuel cell device 1 is used while being fixed indoors, a hydrogen pipe can be used as a hydrogen source. Hydrogen storage alloy 21
The fuel electrode 13 is connected to the fuel electrode 13 via a hydrogen supply pressure regulating valve 23 and a hydrogen supply solenoid valve 24 via a hydrogen gas supply path 22. The pressure regulating valve 23 regulates the pressure of the hydrogen gas supplied to the fuel electrode 13 and may be of a general configuration. The solenoid valve 24 opens and closes the hydrogen gas supply path 22.

A hydrogen storage gauge 25 is attached to the tank of the hydrogen storage alloy 21. As the hydrogen fuel gauge 25, a type in which a hydrogen storage alloy is bonded with a binder to measure its electric resistance value can be used (Japanese Patent Application No. 11-162279, applicant's serial number: EQ99042, agent) Reference number: P0148). General-purpose hydrogen gas pressure sensors are provided as a hydrogen primary pressure sensor 27 and a hydrogen secondary pressure sensor 28 on the upstream side of the pressure regulating valve 23 and on the downstream side of the electromagnetic valve 24, respectively.

The filling of hydrogen into the hydrogen storage alloy 21 is as follows:
Attach the filling valve to the external hydrogen gas source and set the relief valve 3
2. The purge valve 33 and the hydrogen supply electromagnetic valve 24 are closed, and the purge electromagnetic valve 34 is opened. A storage nozzle 61 for spraying water is attached to the tank of the hydrogen storage alloy 21. Hydrogen storage alloy 2 with water supplied from nozzle 61
By cooling 1, the hydrogen storage capacity of the hydrogen storage alloy 21 is improved. A general-purpose hydrogen storage alloy 21 can be used. For example, for example, Ti-Fe alloy, Ti-M
An n-based alloy, a La-based alloy, a Mn-based alloy, a V-based alloy, or the like can be used.

In the hydrogen gas discharge system 35, a hydrogen discharge solenoid valve 37 opens and closes according to a predetermined rule. The hydrogen exhaust solenoid valve 37 is closed to stop the flow of the hydrogen gas and to prevent the electrolyte membrane 12 from being unnecessarily dried from the fuel electrode 13 side. If the hydrogen exhaust solenoid valve 37 is closed, hydrogen gas around the fuel electrode 13 will be consumed.
It is opened according to a predetermined rule to supply fresh hydrogen gas to the fuel electrode 13. Reference numeral 36 denotes a hydrogen exhaust solenoid valve 3
7 is a check valve for preventing external air from flowing into the fuel electrode 13 when the valve 7 is opened.

The air supply system 40 takes in air as oxidizing gas from outside air and sends it to the air chamber A of the fuel cell main body 10. The air from which dust has been removed by the filter 41 is sent into the air manifold 14 by the air supply fan 42. The air supply fan 42 is driven by a servomotor, and its air volume can be arbitrarily controlled. The air sent into the air manifold 14 enters the air chamber A of the fuel cell body 10, where the air electrode (oxidation electrode)
Supply necessary oxygen to 11. Then, the air warmed by the reaction through the air chamber A passes through the tank of the hydrogen storage alloy 21 through the first duct 43 and heats it.
Thereby, the hydrogen release efficiency of the hydrogen storage alloy 21 is improved. After that, the water vapor component is sent to the water condenser 65 through the second duct 44 and condensed and recovered. Reference numeral 45 denotes a filter, which prevents entry of dust and dirt from the outside when the operation of the fuel cell device is stopped. A temperature sensor 46 is attached to the first duct 43, and the temperature of the exhaust air discharged from the fuel cell main body 10 is measured. Second duct 44
The temperature sensor 47 is also attached to measure the temperature of the exhaust air discharged from the water condenser 65.

The water supply system 50 supplies water directly to the air electrode 11 side of the fuel cell body 10 to control the evaporation of the electrolyte membrane 12 and / or the temperature of the fuel cell body 10. The water stored in the water tank 55 is given a predetermined water pressure by the water direct injection pump 54 and is jetted from the water direct injection nozzle 51. Numeral 53 in the figure denotes a direct-fountain solenoid valve 53, which is closed when the water supply system 50 is off to prevent unnecessary evaporation of water. The filter 52 prevents foreign matter from entering the fuel cell body 10 before it occurs. A water level sensor 56 is attached to the water tank 55, and when the water level falls below a predetermined range,
Alarm means not shown (alarm light, alarm sound, etc.)
Informs the user of water shortage. When such a water shortage occurs, the water supply electromagnetic valve 68 is opened and water is injected from the water supply port 67 into the water tank 55. On the other hand, when the water level exceeds the predetermined range, in order to prevent water overflow, the control device operates to reduce the water recovery capacity of the water condenser 65.

Air manifold 1 from water direct injection nozzle 51
The water jetted to 4 directly enters the air chamber A of the fuel cell main body 10 from the upstream opening by the water force. Water evaporates preferentially in the air chamber A by removing latent heat from the surrounding air, the electrode surface, and the separator surface. Thereby, excessive evaporation of the water in the electrolyte membrane 12 is prevented. There is also an effect of cooling the fuel cell main body 10 by removing latent heat. The water supplied in this manner is pushed by gravity and airflow, and the first duct 43 → the tank of the hydrogen storage alloy 21 → the second duct 44
→ Move to the water condenser 65. The water that has reached the water condenser 65 is returned to the water tank 55 via the direct fountain solenoid valve 66. The water condenser 65 condenses and collects the water vapor contained in the discharged air.

The water from the water direct injection pump 54 is also supplied to the storage nozzle 61 via the storage electromagnetic valve 62. The nozzle 61 sprays water toward cooling fins provided in a hydrogen storage alloy tank and cools the water. The water discharged from the nozzle 61 is passed through the second duct 44 to the water condenser 6.
5 and returned to the water tank 55. The cooling of the hydrogen storage alloy 21 is performed only when hydrogen is stored in the alloy. In the normal operation state of the fuel cell device 1, the storage solenoid valve 62 is closed.

The output system 70 is for taking out the output from the stack of the fuel cell body 10 to the outside. In the example of FIG. 2, the power is sent to the secondary battery 74 and the external motor 77 via the relay switch 71 and the diode 72. Reference numeral 75 is a relay switch, and reference numeral 76 is an inverter. The stack of the fuel cell body 10 has an FC voltage sensor 78 for detecting the entire output voltage and a module therein (the fuel cell body 10).
A module voltage sensor 79 for detecting an output voltage for each of a plurality of sub-stacks is provided.

Next, the operation of the fuel cell device 1 according to the embodiment will be described. FIG. 4 is a block diagram showing main elements involved when controlling the operation of the fuel cell device 1. FIG.
Is a main flow showing the control of the fuel cell device 1. In FIG. 4, the control device 80 and the memory 83 are a control box (not shown in FIG. 1) of the fuel cell device 1.
It is stored in. The memory 83 stores a control program that regulates the operation of the control device 80 composed of a computer, and parameters and lookup tables for executing various controls.

First, the operation of the hydrogen gas supply system 20 performed in step 1 of FIG. 5 will be described. At startup,
With the hydrogen discharge electromagnetic valve 37 kept closed, the hydrogen pressure regulating valve 23 is adjusted so that hydrogen gas is supplied to the fuel electrode 13 at a predetermined concentration lower than the explosion limit. When the fuel cell apparatus 1 is operated with the hydrogen exhaust solenoid valve 37 closed, the fuel electrode 13 is affected by N ₂ , O _2, or generated water that passes through the air electrode.
As the partial pressure of hydrogen consumed in the process gradually decreases, the output voltage also decreases, and a stable voltage cannot be obtained.

Therefore, the exhaust valve 37 is opened based on a predetermined rule to exhaust the gas having a reduced hydrogen partial pressure, and the atmosphere gas of the fuel electrode 13 is refreshed. The predetermined rules are stored in the memory 83, and the exhaust solenoid valve 3
The opening and closing of the valve 7 and the adjustment of the pressure regulating valve 23 are executed by the control device 80 by reading the rules from the memory 83. In this embodiment, the output voltage of the entire stack is monitored by the FC voltage sensor 78, and when the output voltage drops below a predetermined threshold, the exhaust solenoid valve 37 is opened for a predetermined time (for example, one second). Alternatively, a time interval at which the output voltage starts to decrease when the fuel cell device 1 is operated with the exhaust electromagnetic valve 37 closed is measured in advance, and the exhaust gas is exhausted at a cycle substantially equal to or slightly shorter than the time interval. To release the solenoid valve 37,
The opening and closing of the exhaust solenoid valve 37 is controlled intermittently. By making the flow of the hydrogen gas intermittent as in this embodiment, the drying of the electrolyte membrane 12 on the fuel electrode 13 side can be reduced as much as possible. This eliminates the need to add a humidifier to the hydrogen gas supply system.

Next, the operation of the air supply system 30 executed in step 3 of FIG. 5 will be described. Fuel cell body 1
The temperature of the exhaust air immediately after being discharged from
6 to detect. If the temperature exceeds, for example, 80 ° C., the fuel cell body 10 may be burned.
The rotation speed of the fan 42 is increased to increase the air volume, thereby lowering the temperature of the air electrode 11 which is a heat generation source. When the detected temperature is equal to or lower than 80 ° C., the load of the fuel cell main body 10 is detected. In the case of this embodiment, the output voltage of the stack is detected using the FC voltage sensor 78. The control device 80 adjusts the detected voltage value so as to optimize the air volume based on the relationship stored in the memory 83 in advance. The air volume is adjusted by controlling the rotation speed of the air supply fan 42.

Next, the operation of the water supply system 50 executed in step 5 of FIG. 5 will be described. The water in the tank 55 is pumped by the pump 54. Then, the water is sprayed from the water injection nozzle 51. As a result, the water is supplied to the air chamber A of the fuel cell main body 10 in a liquid state (fog state). The supply amount to the air chamber A is controlled by controlling the output of the pump 54.

The supply amount of water is determined in advance according to the temperature of the fuel cell body. That is, the minimum amount of water required to maintain the fuel cell body at that temperature is supplied. Pump 4
This is for minimizing the power loss due to 6. When the temperature of the fuel cell body falls below a predetermined temperature (for example, 30 ° C.), the supply of water can be stopped. Further, at another predetermined temperature (for example, at a temperature of 50 ° C. or less and exceeding 30 ° C.), the supply of water can be intermittent. The relationship between the temperature of the fuel cell body 10 and the amount of water to be supplied at that time is stored in the memory 83. In addition, the water supply system 50 may be operated every predetermined time (for example, 5 to 10 seconds) to intermittently supply water.

Next, the operation of the fuel cell device 1 of the embodiment at the time of startup will be described with reference to FIG. When an ignition switch (not shown) is turned on (step 11), the pump 54 is turned on (step 1).
3). Then, regardless of the operating condition (operating temperature) of the fuel cell main body 10, the nozzle 5 is controlled to have a predetermined water injection amount.
Water is injected from step 1 (step 15). In order to protect the fuel cell body 10 from an abnormal reaction, it is desirable that the amount of water injected into the air electrode 11 be the maximum amount. Thereafter, the air supply system 40 is turned on (step 17). At this time, the air volume of the fan 42 is also maximized to cool the fuel cell main body 10 and prevent an abnormal reaction. Subsequently, the hydrogen supply system 20 is turned on (step 19). When a desired output voltage is confirmed in the stack of the fuel cell body 10, power is output to the outside.

In the above, the operation of the air supply system 40 may be performed before the operation of the water supply system 50. Further, the air supply system 40 may be operated after the hydrogen supply system 20 is operated.
However, before operating the hydrogen supply system 20, the water supply system 50
It is necessary to operate. Since air is present in the fuel cell main body 1 regardless of whether the air supply system 40 is operating or not, if hydrogen is supplied while the electrolyte membrane 12 is dry,
Abnormal combustion may occur. In other words, when this abnormal heat is generated, water is injected before the hydrogen is supplied so that the fuel cell body 1 is not damaged so that the fuel cell body 1 is not damaged.
Keep 1 wet. By doing so, the abnormal heat is converted to the heat of evaporation of water, and further, the wetting of the electrolyte membrane 12 is promoted, thereby preventing the fuel cell body 1 from being damaged.

Next, control when the fuel cell device 1 of this embodiment is stopped will be described with reference to FIGS. 7 and 8. FIG. FIG. 7 shows a flow for confirming that the ignition key has been turned off. In step 21, it is always monitored whether or not the voltage value of the ignition signal is larger than a threshold value (5.2V). When the occupant (operator) turns on the ignition switch, the control device 8
The CPU of 0 detects the input signal. In the fuel cell device 1 of this embodiment, the ignition signal is always maintained at more than 5.2 V when the ignition is turned on. If the ignition is on, step 2
At 2 the ignition count becomes 0 and the steady operation continues. If the ignition is turned off, step 21
At, the ignition signal becomes 5.2 V or less, and the routine proceeds to step 23. In step 23, the value of the ignition count is increased by one. In step 24,
When an ignition signal of 5.2 V or less is detected more than three times, it is recognized that the ignition has been turned off, and a stop operation process is performed in step 25.

FIG. 8 shows the flow of the stop operation processing. In the operation stop processing, first, in step 30, the relay switch 71 is turned off to disconnect the fuel cell device 1 from the motor 77 as a load. Next, the hydrogen supply solenoid valve 2
4 is closed to stop the supply of hydrogen (step 31). At this time, it is preferable to release the hydrogen exhaust solenoid valve 37. In step 32, the operation of the accessories other than the air supply fan 42 is stopped. Specifically, the operation of the water supply pump 54 is stopped. Note that the water condenser 65 is in an operating state. In step 33, the relay switch 75 is removed to disconnect the fuel cell device 1 from the battery 74. In step 34, the ignition on / off state is confirmed again (the flow of FIG. 7 is executed). When the ignition is on, the system is restarted (step 35). If it can be confirmed that the ignition is off, the process proceeds to step 36. In step 36, the operation state of the air supply fan 42 is confirmed, and if the fan 42 is stopped, it is driven (step 37). Normally, the fan 42 maintains the driving state even after the ignition stops. It is assumed that the driving state (rotation speed) of the air supply fan 42 after the stop of the ignition maintains the driving state (rotation speed) immediately after the stop of the ignition. Then, in step 38, time measurement is started from step 36, and if the drive of the fan 24 has elapsed for 10 minutes, the flow proceeds to step 39. In step 39, the output voltage of each sub-stack of the fuel cell main body 1 (in this embodiment, the stack is composed of four sub-stacks) is measured by the module voltage sensor 79, and the voltage of all the sub-stacks is 10 V or less. If so, the moisture is substantially removed from the air chamber A of the fuel cell main body 1, and it is determined that the moisture has been substantially dried, and the rotation of the air supply fan 41 is stopped (step 40).

[0036]

According to the fuel cell device of the present invention, since the air blowing is continued in accordance with a predetermined rule even after the device is stopped, unnecessary moisture is removed from the fuel cell main body, especially from the air chamber.
Therefore, generation of hydrogen gas due to electrolysis of water can be reliably prevented. Therefore, a safe fuel cell device can be provided.
The system design is simplified by using the blowing time as a control parameter in order to reliably remove water from the fuel cell body. If the state of the fuel cell body is monitored to determine the degree of water removal, the generation of hydrogen gas can be more reliably prevented.

The present invention is not limited to the description of the above-described embodiments and examples. Various modifications are included in the present invention without departing from the scope of the claims and within the scope of those skilled in the art.

Hereinafter, the following matters will be disclosed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between stack voltage and time after stopping a fuel cell (continuation of air supply fan rotation).

FIG. 2 is a schematic diagram showing a configuration of a fuel cell device according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a basic configuration of the fuel cell body.

FIG. 4 is a schematic diagram showing a control system of the fuel cell device.

FIG. 5 is a main flow showing the operation of the fuel cell device.

FIG. 6 is a flowchart showing control when the fuel cell device is started.

FIG. 7 is a flowchart showing control at the time of stop.

FIG. 8 is a flowchart showing control at the time of stop.

[Description of Signs] 1 Fuel cell device 10 Fuel cell main body 11 Air electrode 12 Electrolyte membrane 13 Fuel electrode 20 Hydrogen supply system 35 Hydrogen exhaust system 40 Air supply system 50 Water supply system 70 Output system

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Kamiya 2-19-12 Sotokanda, Chiyoda-ku, Tokyo Inside Equos Research Co., Ltd. (72) Inventor Kiyoshi Kawamoto 2-19 Sotokanda, Chiyoda-ku, Tokyo No. 12 Inside Equos Research Co., Ltd. (72) Inventor Shingo Ishida 2-19-12 Sotokanda, Chiyoda-ku, Tokyo F-term inside Equos Research Co., Ltd. 5H026 AA06 CC03 5H027 AA06 KK31 KK46 KK54 MM03 MM04

Claims (23)

[Claims] A fuel cell body including an electrolyte and a fuel electrode and an oxidation electrode disposed so as to sandwich the electrolyte; an oxidizing gas supply device configured to supply an oxidizing gas to an oxidizing gas chamber of the fuel cell body; A fuel cell device comprising: a fuel gas supply device that supplies a fuel gas to a fuel gas chamber of the fuel cell main body; and a water supply device that supplies water to the oxidizing gas chamber in a liquid state. The fuel cell device according to claim 1, wherein when the fuel cell device is stopped, the oxidizing gas supply device is stopped after the water supply device is stopped. 2. The fuel cell device according to claim 1, wherein, when the fuel cell device is stopped, the water supply device is stopped after the fuel gas supply device is stopped. 3. The fuel cell device according to claim 1, wherein the oxidizing gas supply device is stopped after moisture is substantially removed from an air chamber of the fuel cell body. 4. The fuel cell device according to claim 1, wherein, after the water supply device is stopped, the oxidizing gas supply device is driven for 5 minutes or more and then stopped. 5. The fuel cell device according to claim 1, wherein, after the water supply device is stopped, the oxidizing gas supply device is driven for 10 minutes or more and then stopped. 6. A detecting means for detecting a state of the fuel cell main body, wherein the oxidizing gas supplying means is stopped based on a detection result of the detecting means after the fuel gas supply device and the water supply device are stopped. The fuel cell device according to claim 1, wherein: 7. The fuel cell system according to claim 6, wherein the detecting means detects a voltage of the fuel cell main body, and the oxidizing gas supply means is stopped when the detected voltage becomes equal to or less than a predetermined value. 3. The fuel cell device according to item 1. 8. The detecting means directly or indirectly detects the temperature of the fuel cell main body, and when the detected temperature falls below a predetermined value, the oxidizing gas supply means is stopped. The fuel cell device according to claim 6, wherein: 9. The detecting means detects a predetermined component contained in the exhaust gas discharged from the fuel cell main body, and when the predetermined component falls below a predetermined value, the oxidizing gas supply means stops. The fuel cell device according to claim 6, wherein: 10. The fuel cell device according to claim 9, wherein the predetermined component is hydrogen or water vapor. 11. A fuel cell main body including an electrolyte, a fuel electrode and an oxidation electrode disposed so as to sandwich the electrolyte, an oxidizing gas supply device for supplying an oxidizing gas to an oxidizing gas chamber of the fuel cell main body, A method for stopping a fuel cell device comprising: a fuel gas supply device that supplies a fuel gas to a fuel chamber of the fuel cell body; and a water supply device that supplies water to the oxidizing gas chamber in a liquid state. Stopping the supply of the water and then stopping the supply of the oxidizing gas. 12. When the fuel cell device is stopped,
The method according to claim 11, wherein the water supply device is stopped after the fuel gas supply device is stopped. 13. The method according to claim 11, wherein the oxidizing gas supply device is stopped after moisture is substantially removed from an air chamber of the fuel cell body. 14. The stopping method according to claim 11, wherein the oxidizing gas supply device is driven for 5 minutes or more after the water supply device is stopped, and then stopped. 15. After the water supply device is stopped, the oxidizing gas supply device is driven for 10 minutes or more and then stopped.
The stopping method according to claim 11, wherein: 16. A detecting means for detecting a state of the fuel cell main body, wherein the oxidizing gas supplying means is stopped based on a detection result of the detecting means after the fuel gas supply device and the water supply device are stopped. The stopping method according to claim 11, wherein 17. The fuel cell system according to claim 16, wherein the detecting means detects a voltage of the fuel cell main body, and the oxidizing gas supply means is stopped when the detected voltage becomes a predetermined value or less. Stop method described in. 18. The fuel cell system according to claim 18, wherein the detecting means directly or indirectly detects the temperature of the fuel cell main body, and the oxidizing gas supply means is stopped when the detected temperature falls below a predetermined value. 17. The stopping method according to claim 16, wherein: 19. The detecting means detects a predetermined component contained in exhaust gas discharged from the fuel cell main body,
17. The stopping method according to claim 16, wherein the oxidizing gas supply unit is stopped when the predetermined component falls below a predetermined value. 20. The method according to claim 19, wherein the predetermined component is hydrogen or steam. 21. A fuel cell main body including an electrolyte, a fuel electrode and an air electrode arranged to sandwich the electrolyte, means for supplying air to an air chamber of the fuel cell main body, Means for supplying hydrogen to the fuel chamber; means for directly spraying water in a liquid state to the air electrode of the fuel cell main body; and forcibly drying the air chamber of the fuel cell main body after stopping the fuel cell device. Means for causing a fuel cell device. 22. A fuel cell main body including an electrolyte, a fuel electrode and an air electrode disposed so as to sandwich the electrolyte, means for supplying air to an air chamber of the fuel cell main body, Means for supplying hydrogen to the fuel chamber; means for supplying water to the air electrode of the fuel cell body; and means for forcibly drying the fuel cell body after the fuel cell device is stopped. Fuel cell device. 23. A method for controlling operation of a fuel cell device, wherein water is directly sprayed into an air chamber of a fuel cell body in a liquid state,
An operation control method for a fuel cell device, comprising: circulating air to the air chamber at a predetermined timing after stopping the fuel cell device.