JPH08138704A - Fuel cell humidifier, humidification control device, and manufacture of humidifier - Google Patents

Abstract

PURPOSE: To prevent excess wetting of a supply electrode, and prevent drop in output of a fuel cell by supplying water in a good state of steam. CONSTITUTION: A hydrogen gas humidifier 110 is constituted with a porous film 111, and separators 113, 115 which interpose the porous 111 from both sides and form a hydrogen gas flow path 113p and a water flow path 115p respectively. The porous film 111 is a polyolefin porous film and has hydrophilic nature. In the hydrogen gas humidifier 110, water in the water flow path 115p permeates the porous film 111 according to the difference between the pressure of water flowing in the water flow path 115p and the pressure of hydrogen gas flowing in the hydrogen gas flow path 113p. Since the porous film 111 has hydrophilic nature, permeated water comes in contact with the porous film 111 in a wide contact area. Water is easily vaporized by receiving heat from both the porous film 111 and the hydrogen gas, humidification is conducted in a good state of steam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell humidifier for humidifying a material gas supplied to an electrode of a fuel cell, a fuel cell humidifier controller for controlling the amount of humidification, and a method for manufacturing the humidifier. And about.

[0002]

2. Description of the Related Art In a polymer electrolyte fuel cell, which is one of the fuel cells, the reaction of converting hydrogen gas into hydrogen ions and electrons at the anode and oxygen gas, hydrogen ions and electrons at the cathode are as shown in the following equation. From which water is produced.

Anode reaction: H ₂ → 2H ⁺ + 2e ^- Cathode reaction: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O

The hydrogen ions generated at the anode become hydrated (H ⁺ .xH ₂ O) and move to the cathode in the electrolyte membrane. For this reason, water becomes insufficient in the vicinity of the surface of the electrolyte membrane on the anode side, and in order to continuously carry out the above-mentioned reaction, it is necessary to replenish this insufficient water. The electrolyte membrane used in the polymer electrolyte fuel cell has good electric conductivity in a wet state, but when the water content decreases, the electric resistance of the electrolyte membrane increases and the electrolyte membrane does not sufficiently function as an electrolyte. Will stop the electrode reaction.

This water replenishment is generally performed by humidifying the fuel gas. As a device for humidifying the fuel gas, a device for bubbling the fuel gas to humidify is well known. However, for example, when trying to use this bubbling humidifier for a fuel cell stack mounted on an electric vehicle, a bubbler with a large volume must be prepared and heated by an electric heater, which is practical in terms of volume and energy consumption. Hard to say.

Therefore, as another humidifying device, a device for humidifying the fuel gas through a porous membrane made of tetrafluoroethylene resin has been proposed (for example, Japanese Patent Laid-Open No. 3-269958). This is because water and gas are made to flow through the porous membrane and the pressure of water is made higher than that of gas,
Due to the pressure difference, water is permeated to the gas side through the porous membrane, and the water is vaporized on the surface of the porous membrane to try to humidify the gas.

The humidifying device using such a porous membrane can be incorporated inside the solid polymer fuel cell stack or can be assembled integrally on the outside of the solid polymer fuel cell stack, and the humidifying part can be provided. It can be made compact, and since the heat generated by the reaction of the fuel cell can be used as heat for vaporizing water, it does not require a heating means such as an electric heater and is excellent in terms of energy consumption. ing.

[0008]

However, this humidifying device has a problem that water can be supplied only in the state of water droplets, not in the state of good water vapor. In this humidifier, since a water-repellent porous membrane made of tetrafluoroethylene resin is used, water that has passed to the gas flow path side becomes spherical water droplets on the gas side surface of the porous membrane. I will end up. Since the water droplets have a small contact area with the gas, they cannot be easily vaporized, and successively receive water supplied through the porous membrane to grow into larger water droplets. Then, at last, it falls by gravity or is blown off by the gas, and a large amount of water drops are scattered. In this way, the humidifying water does not reach the expected steam state,
A large amount of water droplets are supplied to the anode.

If the same water is used but is moistened in the form of water droplets, the anode becomes too wet and the pores of the electrode base material are blocked. As a result,
This hindered the diffusion of fuel gas to the anode, resulting in a decrease in the output of the polymer electrolyte fuel cell.

Japanese Unexamined Patent Publication (Kokai) No. 3-269958 describes an example in which a fluorophore made by Sumitomo Electric Co., Ltd. and a membrane made by Japan Gore-Tex are used as a porous membrane made of tetrafluoroethylene resin. Therefore, the present inventor conducted an experiment using this film. In this experiment, among these membranes, the commercially available product having the smallest pore size and the largest thickness, that is, the product having the least water permeation as the porous membrane was used. As a result, the water was still supplied only in the form of water drops, and the expected good steam was not generated.

The fuel cell humidifier according to the present invention has been made in view of these problems. It is possible to supply water in a good water vapor state to prevent the supply electrode from becoming too wet. The purpose is to prevent the output of the fuel cell from decreasing.

On the other hand, the humidification control device for a fuel cell according to the present invention aims to optimally adjust the humidification amount.

[0013]

In order to achieve such an object, the following constitution is adopted as a means for solving the above problems.

That is, the humidifying device for a fuel cell of the present invention is a humidifying device for humidifying a material gas supplied to an electrode of a fuel cell, which is in contact with a water flow path and the material gas flow path. The gist of the present invention is to provide a porous membrane that permeates the water according to the pressure difference between the material gas and the material gas, and the porous membrane has hydrophilicity.

In the fuel cell humidifier having such a structure, the porous membrane may be a polyolefin (C _n H _2n ) resin film having a large number of pores having a diameter of 10 ^-8 m to 10 ^-7 m. . Further, the porous membrane may be configured to have a large number of pores whose pore diameter is narrowed by silicone. The porous film may be bent and arranged three-dimensionally.

A humidification control device for a fuel cell according to the present invention is a humidification control device for controlling a humidification amount of a material gas supplied to an electrode of a fuel cell, which is in contact with a water flow path and the material gas flow path. A porous membrane that permeates the water in accordance with the pressure difference between the water and the material gas, a water pressure detection unit that detects the water pressure of the water flow path, and a gas pressure of the material gas flow path. Gas pressure detecting means, operating state detecting means for detecting the operating state of the fuel cell, and necessary vapor amount in the material gas required by the fuel cell from the detected operating state of the fuel cell With the water vapor amount calculation means, the ideal pressure difference calculation means for calculating the ideal pressure difference between the water and the material gas from the calculated required water vapor amount, and the water pressure detected by the water pressure detection means and the gas pressure detection means. The water and material based on the detected gas pressure Scan and that the pressure difference and control means for controlling at least one of the water pressure or the gas pressure so that the ideal pressure differential, and the gist thereof.

In the fuel cell humidification control device having such a configuration, the operating state detecting means may be provided with a temperature detecting means for detecting the temperature of the fuel cell.
The operating state detecting means may include an impedance detecting means for detecting the impedance of the fuel cell. Further, the operating state detecting means may be configured to include a gas flow rate detecting means for detecting a flow rate of the material gas discharged from the fuel cell, or a current detecting means for detecting a load current of the fuel cell. It may be configured.

Further, in the humidification control device for a fuel cell having the above-described structure, a stop time determination means for determining a stop time of the fuel cell, and a pressure of the water and the material gas when the stop time is determined. It may be configured to include a stop time control unit that controls at least one of the water pressure and the gas pressure so that the difference becomes a large pressure difference equal to or larger than a predetermined pressure difference.

A method for manufacturing a humidifying device for a fuel cell according to the present invention is a method for manufacturing a humidifying device for a fuel cell according to claim 3, which comprises a step of diluting a silicone adhesive with an organic solvent and the dilution. Filtering a solution of the silicone adhesive under pressure using the porous membrane,
The summary is.

[0020]

According to the humidifier for a fuel cell of the present invention having the above-mentioned structure, since the porous membrane has hydrophilicity, it permeates through the porous membrane to reach the material gas side surface. The water that has exuded comes into contact with the porous membrane with a large contact area. Therefore, since heat can be received from both the porous membrane and the material gas, the water is easily vaporized and is supplied into the material gas in the state of good water vapor. On the other hand, in the case of the conventional water-repellent porous film, the water leached on the material gas side surface of the porous film becomes spherical water droplets, which is only a point for the porous film. They cannot come into contact with each other, so that the water droplet cannot receive heat from the porous membrane and is not vaporized.

According to the humidifier of the third aspect of the fuel cell, the amount of water permeating from the porous membrane is reduced by narrowing the pore diameter. For this reason, it becomes possible to use a porous membrane which cannot be used as it is because the amount of humidification is too large.

In the fuel cell humidifier of the fourth aspect, since the porous membrane is bent and arranged three-dimensionally, the porous membrane having a larger surface area is incorporated in the humidifier having a small volume. It becomes possible. Therefore, a larger amount of humidification can be realized with a humidifier having a small volume.

According to the humidification control device for a fuel cell of the fifth aspect, the required water vapor amount in the material gas required by the fuel cell is calculated from the operating state of the fuel cell detected by the operating state detecting means. The ideal pressure difference between water and the material gas is calculated by the ideal pressure difference calculation means from the required amount of water vapor. Then, by controlling at least one of the water pressure and the gas pressure by the control means, the pressure difference between water and the material gas is controlled to the ideal pressure difference. The porous membrane permeates water according to its ideal pressure difference controlled by the control means. The permeated water is vaporized into water vapor and supplied to the material gas. As a result, the amount of water that permeates the porous membrane is ideally determined according to the operating state of the fuel cell.

According to the humidification control device for a fuel cell of the sixth aspect, the required water vapor amount calculating means calculates the required water vapor amount in the material gas in accordance with the temperature of the fuel cell detected by the temperature detecting means. . Therefore, the higher the temperature of the fuel cell, the greater the amount of saturated water vapor in the gas, so that it becomes possible to increase the required amount of water vapor according to the increase in the temperature of the fuel cell, and as a result, the temperature of the fuel cell rises. The amount of humidification increases accordingly.

According to the humidification control device for a fuel cell of the seventh aspect, the required water vapor amount calculation means calculates the required water vapor amount in the material gas in accordance with the impedance of the fuel cell detected by the impedance detection means. . The higher the impedance, the drier the membrane-electrode assembly, that is, the fuel cell unit. Therefore, the pressure difference between the water pressure and the gas pressure is increased according to the increase in the impedance to increase the amount of humidification.

According to the humidification control device of the fuel cell of the present invention, the required water vapor amount calculation means calculates the required water vapor content in the material gas in accordance with the flow rate of the material gas from the fuel cell detected by the gas flow rate detection means. The amount is calculated. The higher the gas flow rate, the larger the amount of humidifying water required in the fuel cell. Therefore, the pressure difference between the water pressure and the gas pressure is increased in accordance with the increase in the gas flow rate to increase the humidifying amount.

According to the humidification control device of the fuel cell of the ninth aspect, the required water vapor amount calculation means calculates the required water vapor amount in the material gas in accordance with the load current of the fuel cell detected by the current detection means. It Since the gas flow rate of the fuel cell is determined according to the load current, like the gas flow rate,
The higher the load current, the larger the amount of humidifying water required in the fuel cell. Therefore, the humidification amount is increased by increasing the pressure difference between the water pressure and the gas pressure as the gas flow rate increases.

According to the humidification controller for a fuel cell of the tenth aspect, when the stop determination means determines that the fuel cell is stopped, the pressure difference between the water and the material gas is equal to or more than a predetermined pressure difference. At least one of water pressure and gas pressure is controlled by the stop time control means so that a large pressure difference is obtained.

According to the method of manufacturing a humidifying device of claim 11, the solution of the silicone adhesive diluted with the organic solvent is filtered under pressure using the porous membrane, so that only the solvent is the porous membrane. Of the silicone adhesive, and a part of the silicone adhesive acts so as to remain on the surface and inside of the porous membrane.

[0030]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above.

FIG. 1 is a schematic configuration diagram of a polymer electrolyte fuel cell stack (hereinafter referred to as a fuel cell stack) 1 as a first embodiment to which a fuel cell humidifying device of the present invention is applied. The fuel cell stack 1 includes a plurality of unit cells 1
A power generation unit 100 including 0, and a humidification unit 200 including a hydrogen gas humidifier 110 that humidifies hydrogen gas and an oxygen-containing gas humidifier 120 that humidifies oxygen-containing gas (air). The power generation unit 100 includes a tightening bolt 312, between the two end plates 300, 310.
The humidifying unit 200 is assembled between the one end plate 310 and the third end plate 320 by tightening bolts 322 and 324.

In the power generation unit 100, a plurality of cells 10 (three in this embodiment) are laminated, cooling water passages 20 and 30 are provided on both sides in the laminating direction, and further cooling water passages 20 and 30 are provided.
The configuration is such that the current collectors 40 and 50 are provided outside the 30.

The structure of the cell 10 will be described below. The cell 10 has an electrolyte membrane 11 as shown in the structural diagram of FIG.
And a cathode 12 and an anode 13 serving as a gas diffusion electrode sandwiching the electrolyte membrane 11 from both sides, and an oxygen-containing gas and a fuel gas flow between the cathode 12 and the anode 13 sandwiching the sandwich structure from both sides. It is composed of separators 14 and 15 that form a passage.

The electrolyte membrane 11 is an ion-exchange membrane made of a polymer material, for example, a fluororesin, and exhibits good electric conductivity in a wet state. The cathode 12 and the anode 13 are made of carbon cloth woven with a yarn made of carbon fiber.
Carbon powder carrying platinum or an alloy of platinum and another metal as a catalyst is kneaded into the gap of the cloth. The separators 14 and 15 are formed of a dense carbon plate. The separator 14 on the cathode 12 side forms a flow path for the oxygen-containing gas, which is a material gas, with the surface of the cathode 12, and also forms an oxygen gas flow path 14p that serves as a water collection path for water generated in the cathode 12. In addition, the separator 15 on the anode 13 side forms a hydrogen gas flow path 15p that forms a flow path of a mixed gas of hydrogen gas that is a fuel gas and water vapor with the surface of the anode 13.

This is the basic structure of the cell 10, and the current collector plates 40 and 50 (FIG. 1) arranged outside the cell 10 serve as the collector electrodes of the cathode 12 and the anode 13 of these cells 10. . The collector plates 40 and 50 are made of copper (Cu)
It is formed by. Insulating plates 60 and 70 are interposed between the current collector plate 40 and the end plate 300 and between the current collector plate 50 and the end plate 310.

The structure of the hydrogen gas humidifier 110 will be described below. As shown in the structural diagram of FIG. 3, the hydrogen gas humidifier 110 is composed of a porous film 111 and separators 113 and 115 that sandwich the porous film 111 from both sides and form hydrogen gas and water flow paths. Has been done.

The porous membrane 111 is a polyolefin-based porous film having hydrophilicity, a porosity of 50 [%] or more, and an average pore diameter of 0.05 [μm].
It is of a degree. The porous membrane 111 allows water to permeate according to the pressure difference between both sides of the film. The porous membrane 111 can be obtained, for example, from Asahi Kasei Kogyo under the trade name “HIPORE 1000”.

The separators 113 and 115 are formed of a dense carbon plate which is made by impressing carbon to make gas impermeable. A plurality of convex portions arranged in parallel are provided on the surface of the separators 113 and 115 on the side of the porous membrane 111, and the plurality of convex portions and the porous membrane 111 form a plurality of hydrogen gas flow passages 113p and water flow. Forming a path 115p. In addition, the separators 113 and 115 and the porous film 11
1 is sealed by O-rings 116 and 117, and both sides of the porous membrane 111 in the longitudinal direction are sealed by seal members 118 and 119.

Although the separator 113 is formed of gas impermeable carbon in the embodiment, it may be formed of any material as long as it is not corroded by hydrogen gas and has excellent thermal conductivity. Also, the separator 1
The material 15 may be formed of any material as long as it is a material stable to water and excellent in thermal conductivity.

The hydrogen gas humidifier 110 thus constructed
Is the hydrogen gas flow path 1 described above in the hydrogen gas circulation path C1.
13p is located and the above-mentioned water flow path 1 is provided in the water circulation path C2.
It is arranged so that 15p is located. As a result, the water in the water channel 115p permeates the porous membrane 111 according to the difference between the pressure of the water flowing in the water channel 115p and the pressure of the hydrogen gas flowing in the hydrogen gas channel 113p. The permeated water vaporizes on the surface of the porous membrane 111 to humidify the hydrogen gas.

The oxygen-containing gas humidifier 120 for humidifying the oxygen-containing gas used in the cell 10 of the fuel cell has the same porous membrane 121 and separators 123 and 125 (FIG. 1) as the hydrogen gas humidifier 110 described above. Therefore, the oxygen-containing gas is caused to flow through the oxygen gas passage 123p of the separator 123. Therefore, the oxygen-containing gas humidifier 120 is configured so that the pressure of the water flowing through the water flow passage 125p and the oxygen gas flow passage 123p.
Depending on the pressure difference between the oxygen-containing gas flowing through the water channel 12
Water in 5p passes through the porous membrane 121. The permeated water vaporizes on the surface of the porous membrane 121 to humidify the oxygen-containing gas.

Next, the fuel gas and oxygen-containing gas passages 14p and 15p of the cell 10, the cooling water passage 20, the water passage 115p and hydrogen gas passage 113p of the hydrogen gas humidifier 110, and the oxygen-containing gas humidifier 120 are formed. Water channel 125p
A connection state of the oxygen gas flow path 123p and the like will be described. The inlets of the cooling water passages 20 and 30 of the power generation unit 100 are connected to a water tank (not shown) via a water passage 510 and a pump 500, and the outlets of the cooling water passages 20 and 30 are connected to hydrogen via the water passage 520. Water channel 115p of the gas humidifier 110 and water channel 1 of the oxygen-containing gas humidifier 120
It is connected to the entrance of 25p. Therefore, the water used as the cooling water in the power generation unit 100 is supplied to the water flow passage 115p of the hydrogen gas humidifier 110 and the water flow passage 125p of the oxygen-containing gas humidifier 120. Further, the outlets of both water flow paths 115p and 125p are connected to a heat exchanger and a water storage tank (not shown) via a water passage 530.

The pump 500 is provided with an electric motor 500a for varying the rotation speed of the pump 500. The electric motor 500a drives the pump 500 at a rotation speed based on a control signal from the outside. Therefore, pump 5
The water pressure in the cooling water flow passage 20 and the water flow passages 115p and 125p can be adjusted by changing the rotation speed of 00.

Separator 113 of the hydrogen gas humidifier 110
The inlet of the hydrogen gas flow passage 113p formed in the above is connected to a hydrogen gas storage tank (not shown) via the hydrogen gas passage 540 and the blower 550, and the outlet of the hydrogen gas flow passage 113p is connected to the hydrogen gas passage It is connected via 560 to the inlet of the hydrogen gas flow path 15p formed in the separator 15 of the cell 10. Therefore, the mixed gas of hydrogen gas and water vapor flows into the hydrogen gas flow path 15p. The outlet of the hydrogen gas flow path 15p is connected to a hydrogen gas recovery tank (not shown) via a hydrogen gas passage 570.

Separator 1 of the oxygen-containing gas humidifier 120
The inlet of the oxygen gas flow passage 123p formed in 23 is connected to the blower 590 via the oxygen gas passage 580, and the outlet of the oxygen gas flow passage 123p is connected to the oxygen gas passage 59.
2 is connected to the inlet of the oxygen gas flow path 14p formed in the separator 14 of the cell 10 through the line 2. Therefore,
A mixed gas of an oxygen-containing gas and water vapor flows into the oxygen gas flow path 14p. Further, the outlet of the oxygen gas flow path 14p is connected to the external atmosphere via the oxygen gas passage 594.

Fuel cell stack 1 constructed in this way
In the above, the chemical energy is directly converted into electric energy by the above-mentioned chemical reaction, but this chemical reaction is smoothly performed by the material gas (hydrogen gas and oxygen-containing gas) humidified by the humidification unit 200.

That is, in the anode 13 of the cell 10,
Hydrogen reacts with hydrogen ions to become electrons, and the generated hydrogen ions combine with water near the anode 13 to be in a hydrated state and move in the electrolyte membrane 11. Therefore, if water is left as it is in the vicinity of the anode 13 of the electrolyte membrane 11, this shortage is replenished by the water vapor in the mixed gas of hydrogen gas and water vapor. As a result, the electrolyte membrane 11 is always in a wet state, hydrogen ions can move smoothly in the electrolyte membrane 11, and the cathode reaction is smoothly performed. At the cathode 12, a reaction for producing water is carried out by hydrogen ions, electrons and oxygen. The water vapor in the mixed gas of the oxygen-containing gas and the water vapor secures the wet state of the electrolyte membrane 11 immediately after the start of operation and reduces the contact resistance between the cathode 12 and the separator 14 or the like.

As described above in detail, in the fuel cell stack 1 of the first embodiment, the hydrogen gas and oxygen-containing gas, which are the material gases to be supplied to the fuel cell, are used as the hydrogen gas humidifier 11.
0 and oxygen-containing gas humidifier 120 humidifies. In this hydrogen gas humidifier 110, since the porous film 111 is of a polyolefin type having hydrophilicity, water that has permeated the porous film 111 contacts the porous film 111 with a large contact area. Therefore, since heat can be received from both the porous film 111 and the hydrogen gas, the water can be easily vaporized and contained in the hydrogen gas in the state of good water vapor, not in the state of water droplets. it can. Therefore, the anode 1 of the cell 10 to which hydrogen gas is supplied
It is possible to prevent the output of the fuel cell stack 1 from being lowered due to the excessively wet state of the fuel cell stack 3.

Further, also in the oxygen-containing gas humidifier 120, since the porous film 121 is made of a hydrophilic polyolefin, the water that has permeated the porous film 121 can be easily vaporized to form water droplets. It can be contained in the oxygen-containing gas in a good water vapor state instead of the above state. For this reason,
It is possible to prevent the cathode 12 of the cell 10, which is the supply destination of the hydrogen gas, from getting too wet.

The graph of FIG. 4 shows the result of measurement of the amount of humidification using Hypore 1000 manufactured by Asahi Kasei Corporation as an example of the porous film 111. The conditions of this experiment were that the oxygen-containing gas supplied to the cathode 12 was air, the pressure thereof was 1.5 atm, and the gas utilization rate of the fuel cell was 100.
[%] And the current density of the fuel cell is 0.3 [A / cm ² ]. In this experiment, water vapor with good mist can be obtained within the measurement range, and as shown in the graph of FIG. 4, the relationship between the pressure difference ΔP acting on the porous membrane 111 and the humidification amount W is shown. , ΔP was 0.2 to 1 [kgf / cm ² ], W could be in the range of 0.01 to 1 [milliliter / cm ² · minute]. This is a practical range when the polymer electrolyte fuel cell is applied to electric vehicle applications.

Various porous membranes having different amounts of water passing were prepared and experiments were conducted to see how they were actually humidified. The observation results are shown below.

Humidification amount is 0.001 [milliliter / cm ² · min]
The degree of humidification is small, and it is not possible to visually judge whether the gas is humidified. The amount of humidification is 0.01 [ml /
In the case of about cm ² · min], the gas is humidified, and a good vapor in the form of a thin mist is obtained. Humidification amount is 0.1 [ml / cm ² ·
In a minute], the gas is humidified and good mist-like water vapor is obtained. When the amount of humidification is about 1 [milliliter / cm ² · min], the gas is humidified and good vapor in the form of a thick mist is obtained. When the amount of humidification is about 10 [milliliter / cm ² · min], the gas is humidified, but many water droplets are scattered,
No mist-like water vapor can be obtained. Humidification amount is 100 [ml /
cm ² · min], a large amount of water is scattered as if it were not a gas but water, and it is not in the state of water vapor.

That is, it is in the range of 0.01 to 1 [milliliter / cm ² · min] that good humidification can be realized. From this fact as well, in the humidifier using the Hypore 1000 described above. It can be seen that good humidification can be performed.

In the fuel cell stack 1 of the first embodiment, the power generation unit 100 and the humidification unit 200 are assembled separately, so that the following effects are obtained. Firstly, since the power generation unit 100 and the humidification unit 200 are separate bodies, the tightening pressure (torque) between the power generation unit 100 and the humidification unit 200 can be set to different magnitudes. Play.

The tightening pressure of the power generation unit 100 is to prevent gas leakage from the fuel cell and to reduce the cell resistance (cell resistance) of the fuel cell to such an extent that power generation is not hindered. Can be decided In general, the gas seal can be secured with a slight tightening pressure, so that the tightening pressure is actually determined by the cell resistance value. On the other hand, since the tightening pressure of the humidifying unit 200 does not generate electricity, the tightening pressure is
It is determined only by the gas sealability.

In the conventional structure in which the humidifying device is integrated with the power generation unit, the humidifying device is hindered by the tightening pressure determined by the cell resistance, that is, the large tightening pressure. When a porous membrane is used in the humidifier as in this example, the membrane is thin and has low strength. Therefore, when the humidifier is tightened with a large tightening pressure, the porous membrane has a gas flow path and a water flow path. It was strongly pressed against the edge of the groove, and the porous membrane was torn.

On the other hand, in the first embodiment, the tightening pressure of the humidifying unit 200 is not limited by the tightening pressure of the power generation unit 100.
Humidification unit 20 with a large tightening pressure as described above
No need to tighten 0. Therefore, damage to the porous membrane can be prevented.

Further, in the fuel cell stack 1 of the first embodiment, since the power generation unit 100 and the humidification unit 200 are assembled separately, there is an effect that the repair is easy. For example, when an abnormality is found in the battery characteristics, conventionally, it is necessary to completely disassemble not only the power generation part but also the humidifier. On the contrary,
In this embodiment, the power generation unit 100 and the humidification unit 2
Since 00 and 00 are separately assembled, the power generation unit 100 and the humidification unit 200 can be disassembled independently, and the repair thereof is easy.

In general, when the power generation unit 100 and the humidification unit 200 are separated, the heat generation of the fuel cell main body cannot be transferred to the humidification unit because both of them are also thermally isolated. Therefore, the efficiency of humidification is reduced in the humidifying unit 200. However, in the first embodiment, since the cooling water used for cooling the fuel cell main body is used for the water flow paths 115p and 125p, power generation is performed. The unit 100 and the humidification unit 200 can be thermally coupled. Therefore, the humidifying unit 2
At 00, the efficiency of humidification is not lowered.

In the first embodiment, the water passage 115p of the hydrogen gas humidifier 110 (and the water passage 125p of the oxygen-containing gas humidifier 120) is connected to the cooling water passage 20 of the power generation unit 100 as a circulation passage. However, instead of this, the water flow path 115p may be a flow path of a system different from the cooling water flow path 20, and the outlet side of the water flow path 115p may be closed.

In the first embodiment, the polyolefin film is used as the porous film 111. However, instead of this, a cellulose type, a polyamide type, a polysulfone type, or a polypropylene type may be used. In short, 0.01 to 1 [ml /
Any hydrophilic porous membrane can be used as long as it can provide a humidification amount in the range of [cm ² · min]. Here, the hydrophilic porous membrane can be distinguished from the water-repellent porous membrane by the shape of the water droplet when the water droplet adheres to the surface of the porous membrane. That is, on the surface of the water-repellent porous film, the water drops are exactly water drops, that is, in the form of spheres, but on the surface of the hydrophilic film, the water drops are not in the form of spheres and are flat on the film surface. It spreads. In addition, when a hydrophilic porous membrane is quantitatively shown, when the contact angle between the water droplet and the surface of the porous membrane when the water droplet adheres to the surface of the membrane is preferably 30 degrees or less, the hydrophilic porous membrane is It shall be defined as a quality membrane.

The second embodiment of the present invention will be described below. FIG. 5 is a structural diagram of the humidifier 600 of the fuel cell of the second embodiment. As shown in FIG. 5, the humidifier 600 of the fuel cell according to the second embodiment is different from the hydrogen gas humidifier 110 according to the first embodiment in that the porous membrane 602 and the separator 60.
4, 606 and a porous carbon sheet 608,
The difference is that 610 is provided. Both sheets 608,
Sealing members 612 to 615 made of dense carbon are joined to both outer sides in the longitudinal direction of 610 to prevent gas leakage in that direction. Although not shown in detail in FIG. 5, the hydrogen gas humidifier 110 of the first embodiment is used.
Similarly to the above, an O-ring may be used to further improve the sealing performance.

In the second embodiment constructed as described above,
The porous film 111 is covered with the sheets 608 and 610. Since the porous film 111 is as thin as tens to hundreds of microns,
If it is left as it is, it may be damaged due to the pressure difference ΔP acting on the porous film 111.
By covering with 10, it is possible to reliably prevent damage to the porous film 111.

The sheets 608 and 610 may be of any type as long as they are excellent in gas and water permeability and have a certain level of strength. Instead of porous carbon, foamed carbon is used. Alternatively, foamed nickel, glass, or a mesh sheet may be used.

The third embodiment of the present invention will be described below. FIG. 6 is a structural diagram of the humidifier 700 of the fuel cell of the third embodiment. As shown in FIG. 6, in the humidifier 700 of the fuel cell according to the third embodiment, the porous membrane 702 is bent and arranged three-dimensionally as compared with the hydrogen gas humidifier 110 according to the first embodiment. The difference is. Although not shown in detail in FIG. 6, the hydrogen gas humidifier 11 according to the first embodiment is used.
As in the case of 0, an O-ring is used to improve the sealing performance.

In the third embodiment constructed as described above,
Since the porous membrane 702 is bent and arranged three-dimensionally, it is possible to incorporate a porous membrane having a larger surface area with a humidifier having a small volume. When the porous membrane 702 is bent, the thickness of each humidifying device increases, but rather than increasing the number of humidifying devices, a large amount of humidifying with one humidifying device reduces the total thickness of the humidifying portion. You can Therefore, a larger amount of humidification can be realized with a humidifier having a small volume.

In the third embodiment, in order to prevent damage to the porous film 702, a support film may be provided along the porous film 702 as in the second embodiment.

The fourth embodiment of the present invention will be described below. FIG. 7 is a structural diagram of a humidifier 800 for a fuel cell according to the fourth embodiment. As shown in FIG. 7, the humidifier 800 of the fuel cell of the fourth embodiment differs from the hydrogen gas humidifier 110 of the first embodiment in the shape of the porous membrane 802. The porous film 802 has a rectangular tubular shape, and a water flow path 804 through which water flows is provided inside the porous film 802, and a support film 806 similar to that of the second embodiment is provided outside the water flow path 804. Flow path 808 formed by separators 808 and 810
Both p and 810p are channels for gas (hydrogen gas or oxygen-containing gas). Although not shown in detail in FIG. 7, the hydrogen gas humidifier 110 of the first embodiment has an O-ring as in the hydrogen gas humidifier 110 to improve the sealing performance.

In the fourth embodiment constructed as described above,
Since the porous film 802 has a three-dimensional structure, it is possible to realize humidification with a larger surface area, and it is more compact. In this embodiment, either the hydrogen gas or the oxygen-containing gas is made to flow in both flow paths 808p and 810p outside the porous membrane 802.
Instead of this, a configuration may be adopted in which hydrogen gas is passed through one channel and oxygen-containing gas is passed through the other channel. With this configuration,
It is possible to simultaneously humidify both the hydrogen gas supplied to the anode 13 and the oxygen-containing gas supplied to the cathode 12 with one humidifier.

In the above-described first to fourth embodiments, good humidification is obtained by using "HYPORE 1000" as the porous membrane 111 (602, 702, 802).
Alternatively, if a polyolefin film having too large pores is used, the amount of humidification may be excessive. Therefore, a technique for transforming such a film having too large pores into an optimal porous membrane by blocking a part of the pores or narrowing the pore diameter will be described below.

As a porous membrane, a hydrophilic cellulose type membrane filter having a pore size of 0.80 micron, a porosity of 72% and a thickness of 125 micron, such as C0 manufactured by Advantech.
Use 80A. A thermosetting silicone adhesive that polymerizes in an addition type reaction, for example, CY52-227 manufactured by Toray Dow Corning Silicone is used. Using these, work is performed according to the following procedures.

The silicone adhesive is diluted with an organic solvent (xylene or toluene). The weight ratio of the silicone adhesive and the organic solvent is about 1: 100 to 2: 100.
At this time, the whole amount of the silicone adhesive is diluted by gradually adding an organic solvent little by little while stirring. Note that if the order is reversed and the silicone adhesive is gradually added to the entire amount of the organic solvent while stirring, the dilution cannot be performed well, so be careful. The silicone adhesive solution diluted with an organic solvent is vacuum degassed at room temperature to remove air bubbles in the solution. By setting the porous membrane in the holder for pressure filtration and filtering this silicone adhesive solution under pressure, only the solvent passes through the porous membrane, and part of the silicone adhesive is deposited on the surface and inside the porous membrane. To remain. The porous membrane in this state is naturally dried at room temperature for about 30 minutes, and then dried by heating at 60 to 80 [° C.] for 30 minutes to completely vaporize the organic solvent remaining on the surface and inside of the porous membrane. . Next, it is heated at 120 [° C.] for 1 hour to cure the silicone adhesive remaining on the surface and inside of the porous film.

In the porous membrane treated in this way, a part of the pores on the surface and inside is blocked by the silicone adhesive and the diameter of most of the pores is narrowed by the silicone adhesive as compared with before treatment. It Therefore, the amount of humidification of the porous film after the treatment is significantly smaller than that before the treatment.

By carrying out such a treatment, the porous membrane which cannot be humidified well due to too much humidification can be used as the porous membrane of the first to fourth embodiments.

The amount of moistening after the treatment is the ratio of the silicone adhesive to the organic solvent, that is, the dilution rate, and the porous membrane is set in a holder for pressure filtration, and the silicone adhesive solution is pressure filtered. It can be determined by the ratio of the area of the porous membrane to the volume of the silicone adhesive solution, that is, the filtration amount per unit area. It can be appropriately determined from the quantity value.

A fuel cell system as a fifth embodiment to which the fuel cell humidification controller of the present invention is applied will be described below. FIG. 8 is a schematic configuration diagram of the fuel cell system. As shown in the figure, the fuel cell system is
The fuel cell stack 1 is the same as that of the embodiment, and a control system 1100 for controlling the humidification amount of hydrogen gas by the hydrogen gas humidifier 110 in the fuel cell stack 1.

The control system 1100 includes a temperature sensor 1105 composed of a thermocouple for detecting the temperature of the power generation unit 100,
A first pressure sensor 1110 that detects the pressure of hydrogen gas supplied to the hydrogen gas flow path 113p of the humidification unit 200.
And a second for detecting the pressure of water supplied to the water flow path 115p.
Pressure sensor 1120 of FIG. Control system 1100
In addition, these sensors 1105, 1110, 112
It comprises an electronic control unit 1200 connected to 0.

The electronic control unit 1200 is configured as a logic circuit centering on a microcomputer, and more specifically, the CPU 1210 and the CPU 1210, which execute predetermined arithmetic operations according to a preset control program, execute various arithmetic operations. ROM 1220 in which necessary control programs and control data are stored in advance, and CPU
A RAM 1230 in which various data necessary for executing various arithmetic processes in 1210 are temporarily read and written, an input interface 1240 for inputting detection signals from the first pressure sensor 1110 and the second pressure sensor 1120,
An output interface 1250 that outputs a control signal to the electric motor 500a according to the calculation result of the CPU 1210 is provided.

The electronic control unit 1200 having such a configuration
The temperature sensor 1105 and the first pressure sensor 11
10 and the second pressure sensor 1120, the electric motor 500a is controlled according to the output signals from the hydrogen gas humidifier 1.
The humidification amount by 10 is adjusted.

This amount of humidification is controlled by adjusting the pressure difference ΔP with the porous membrane 111 as a boundary. The pressure difference control routine for controlling the pressure difference ΔP will be described in detail below with reference to the flowchart of FIG. This pressure difference control routine is stored in the ROM 1220 in the form of a program, and is executed every predetermined time (for example, every 10 msec) after the operation of the power generation unit 100 is started.

When this routine is started, first the CP
U1210 is the temperature T of the power generation unit 100 detected by the temperature sensor 1105, and the first pressure sensor 111.
The hydrogen gas pressure Ph detected by 0 and the water pressure Pw detected by the second pressure sensor 1120 are read via the input interface 1240 (step S10).
0). Next, the required amount H of steam required by the power generation unit 100 of the fuel cell stack 1 is calculated based on the read temperature T (step S110).

The calculation of the required water vapor amount H is made in advance in the ROM.
This is performed using the map A stored in 1220 and showing the correlation between the temperature T and the required amount H of steam. An example of map A is shown in FIG. As shown in FIG. 10, this map A
Is set so that the humidification amount H increases as the temperature T increases. In step S110, step S1
The temperature T read in 00 is compared with the map A to obtain the required amount H of water vapor.

Then, the set differential pressure ΔPset between the water pressure and the hydrogen gas pressure is determined based on the obtained required water vapor amount H (step S120). Required water vapor amount H and set pressure difference ΔP
The set has a correlation in which the logarithms logH and logΔPset of each other change linearly as shown in FIG. 11, and the set differential pressure ΔPset can be calculated from the required water vapor amount H by calculation.

Subsequently, the CPU 1210 causes the step S1.
The hydrogen gas pressure Ph is subtracted from the water pressure Pw read at 00 to obtain the differential pressure ΔP (step S130). After that, the absolute value of the difference between this pressure difference ΔP and the set pressure difference ΔPset is calculated,
This absolute value is compared with the threshold value Pref (step S1).
30). Here, the threshold value Pref is the maximum value of the pressure difference allowed for the differential pressure ΔP from the set differential pressure ΔPset. This threshold value Pref is determined by a minimum value or the like that can control the rotation speed of the pump 500.

When the absolute value of the difference between the differential pressure ΔP and the set differential pressure ΔPset is less than or equal to the threshold value Pref, it is determined that the pressure difference is within the range suitable for obtaining an appropriate amount of humidification, and this routine is executed. finish. When it is larger than the threshold value Pref, the difference between the differential pressure ΔP and the set differential pressure ΔPset is multiplied by the control gain K to obtain the rotational speed increase / decrease amount ΔF (step S150), and CP
The U1210 outputs a control signal to the electric motor 500a via the output interface 1250 to increase or decrease the rotation speed of the pump 500 by the rotation speed increase / decrease amount ΔF (step S
160). In this way, the pressure difference ΔP between the water pressure Pw and the hydrogen gas pressure Ph is controlled to the set pressure difference ΔPset to obtain an appropriate amount of humidification.

According to the humidification controller of the fifth embodiment described above, the required water vapor amount H is calculated based on the temperature T of the power generation unit 100 detected by the temperature sensor 1105, and the required water vapor amount H is calculated according to the required water vapor amount H. , The pressure difference ΔP acting on the porous membrane 111 is controlled to an ideal pressure difference. Therefore, in this humidification control device, the amount of water that permeates the porous membrane 111 can be ideally determined according to the temperature T of the power generation unit 100. That is, the higher the temperature of the fuel cell,
Since the amount of saturated water vapor in hydrogen gas increases, the porous membrane 1
The pressure difference ΔP applied to 11 can be increased to increase the humidification amount of hydrogen gas. Therefore, the power generation unit 10
The hydrogen gas supplied to 0 can be properly humidified.

The sixth embodiment of the present invention will be described below. The sixth embodiment is different from the fifth embodiment in that its hardware is provided with an impedance sensor for detecting the impedance Z of the power generation unit 100, instead of the temperature sensor 1105. Have the same configuration. On the other hand, the software is different in the content of the process of step S110 in the pressure difference control routine executed by the electronic control unit 1200.

In step S110 of the pressure difference control routine of this embodiment, the required amount of water vapor H required by the power generation unit 100 is calculated based on the impedance Z detected by the impedance sensor.

The calculation of the required water vapor amount H is made in advance in the ROM.
This is performed using the map B stored in 1220 and showing the correlation between the impedance Z and the required amount H of water vapor. An example of map B is shown in FIG. As shown in FIG. 12, this map B is set so that the humidification amount H linearly increases as the logarithmic value logZ of the impedance Z increases. In this step, impedance Z is mapped to map B
The required amount of water vapor H is obtained by comparing with. When the processing of the step of obtaining the required amount H of water vapor is completed, the processing after step S130 is executed as in the fifth embodiment.

According to the humidification control apparatus of the sixth embodiment described above, the required water vapor amount H is calculated based on the impedance Z of the power generation unit 100 detected by the impedance sensor, and the required water vapor amount H is calculated in accordance with the required water vapor amount H. The pressure difference ΔP acting on the porous membrane 111 is controlled to an ideal pressure difference. Therefore, in this humidification control device, the porous film 111
The amount of water that permeates through can be ideally determined according to the impedance Z of the power generation unit 100. That is, as the impedance is higher, the cell 10 of the power generation unit 100 is in a dry state, so that the pressure difference ΔP can be increased to increase the humidification amount of hydrogen gas. Therefore, the hydrogen gas supplied to the power generation unit 100 can be properly humidified.

The seventh embodiment of the present invention will be described below. The seventh embodiment is different from the fifth embodiment in that its hardware is provided with a gas flow rate sensor for detecting the flow rate of the fuel gas discharged from the power generation unit 100, instead of the temperature sensor 1105. They are different, and the other configurations are the same. On the other hand, the software is different in the content of the process of step S110 in the pressure difference control routine executed by the electronic control unit 1200.

In step S110 of the pressure difference control routine of this embodiment, the required amount of water vapor H required by the power generation unit 100 is calculated based on the gas flow rate M detected by the gas flow rate sensor.

Calculation of the required water vapor amount H is performed in advance in the ROM.
Gas flow rate M stored in 1220 and required water vapor amount H
This is performed using map C showing the correlation with. An example of map C is shown in FIG. As shown in FIG. 13, this map C is set so that the moisture amount H linearly increases as the gas flow rate M increases. In this step, the required water vapor amount H is obtained by comparing the gas flow rate M with the map C. When the processing of the step of obtaining the required amount H of water vapor is completed, the processing after step S130 is executed as in the fifth embodiment.

According to the humidification control apparatus of the seventh embodiment described above, the required water vapor amount H is calculated based on the gas flow rate M discharged from the power generation unit 100 detected by the gas flow rate sensor, and the required water vapor amount is obtained. According to H, the pressure difference ΔP acting on the porous film 111 is controlled to an ideal pressure difference. Therefore, in this humidification control device, the porous film 111
The amount of water that permeates through can be ideally determined according to the gas flow rate M of the power generation unit 100. That is, the higher the gas flow rate, the larger the amount of humidifying water required in the power generation unit 100. Therefore, the pressure difference ΔP can be increased to increase the amount of humidifying the hydrogen gas. Therefore, the power generation unit 100
It is possible to properly humidify the hydrogen gas supplied to.

The eighth embodiment of the present invention will be described below. The eighth embodiment is different from the fifth embodiment in that the hardware is provided with a current sensor for detecting the load current of the power generation unit 100, instead of the temperature sensor 1105, and the others. Have the same configuration. On the other hand, the software executes step S110 in the pressure difference control routine executed by the electronic control unit 1200.
The contents of the process are different.

In step S110 of the pressure difference control routine of this embodiment, the load current I detected by the current sensor is detected.
The required amount H of steam required by the power generation unit 100 is calculated based on the above.

The calculation of the required water vapor amount H is made in advance in the ROM.
Load current I stored in 1220 and required water vapor amount H
This is done using map D showing the correlation with. An example of the map D is shown in FIG. As shown in FIG. 14, this map D is set so that the moisture amount H linearly increases as the load current I increases. In this step, the required steam amount H is obtained by comparing the load current I with the map C. When the processing of the step of obtaining the required amount H of water vapor is completed, the processing after step S130 is executed as in the fifth embodiment.

According to the humidification controller of the eighth embodiment described above, the power generation unit 10 detected by the current sensor is used.
The required water vapor amount H is calculated based on the load current I of 0, and the pressure difference ΔP acting on the porous membrane 111 is controlled to an ideal pressure difference according to the required water vapor amount H. Therefore, in this humidification control device, the amount of water that permeates the porous membrane 111 can be ideally determined according to the load current I of the power generation unit 100. That is, since the gas flow rate from the fuel cell is determined according to the load current, like the gas flow rate M,
The higher the load current I, the larger the amount of humidifying water required in the power generation unit 100. Therefore, the pressure difference ΔP can be increased to increase the humidifying amount of hydrogen gas. Therefore, the hydrogen gas supplied to the power generation unit 100 can be properly humidified.

In the fifth to eighth embodiments, the required water vapor amount H is calculated based on the temperature of the fuel cell, the impedance, the load current, or the flow rate of the hydrogen gas gas discharged from the fuel cell. Instead of this, the required water vapor amount H may always be a constant value. When the fuel cell is operating in a steady state, the required amount of water vapor H is a relatively stable amount. Therefore, even if a constant value determined uniquely to the fuel cell is set as the required amount of water vapor H, The amount of humidification can be controlled with high accuracy.

In the fifth to eighth embodiments, the required amount of water vapor H is calculated based on any one of the temperature, impedance, load current and gas flow rate of the fuel cell. The required water vapor amount H may be calculated using two or more of these parameters.

The phosphoric acid type fuel cell, the molten carbonate type fuel cell, and the solid electrolyte type fuel cell for stationary use are premised on continuous operation at a constant output state. When applying a fuel cell to an electric vehicle,
As a matter of course, the electric vehicle repeats running, stopping, accelerating and braking, and the operating state of the polymer electrolyte fuel cell changes in a complicated manner. Therefore, when the polymer electrolyte fuel cell is applied to an electric vehicle, it is necessary to perform more precise control. Therefore, by calculating the required amount of water vapor H using two or more parameters, it becomes possible to operate the polymer electrolyte fuel cell with higher accuracy, stability, and high efficiency.

How to calculate the required water vapor amount H using two or more parameters will be described in detail as a ninth embodiment. Here, the case where the impedance Z and the load current I are used as parameters will be described as an example.

In the sixth embodiment in which the impedance Z is used as a parameter, the load current I = large → ΔP = large and the load current I = small → ΔP = small are controlled. on the other hand,
In the eighth embodiment using the load current I as a parameter,
Impedance Z = Large → △ P = Large, Impedance Z =
It is controlled by the logic of small → ΔP = small.

However, in the fuel cell stack, the impedance Z does not necessarily become large when the load current I = large, and the impedance Z does not become large when the load current I = small.
= It cannot be small. This is, as I said,
This is because when a polymer electrolyte fuel cell is applied to an electric vehicle, its operating conditions change every moment.

Therefore, by combining the logic of the sixth embodiment and the logic of the eighth embodiment, the load current I = large and the impedance Z = large → ΔP =
Large, load current I = small, and impedance Z = small → ΔP =
However, if the load current I = large and the impedance Z = small, and the load current I = small and the impedance Z = large, ΔP is not changed, and control is performed to see the situation for a while.

This is because, for example, when the load current I = high and the impedance Z = small, the load current I increases, so the amount of humidification must be increased. However, the impedance Z is already low and there is a tendency for over-wetting. Therefore, if the humidification amount is increased as it is, the fuel cell may be completely wetted and the fuel cell may stall. While watching the situation for a while, the impedance Z gradually recovered,
If the load current I = high and the impedance Z = high, the control of ΔP = high may be performed at that time.

When the load current I is small and the impedance Z is large, the load current I is small and the amount of humidification must be reduced. However, since the impedance Z is already large and there is a tendency to be too dry, This is because if the amount of humidification is reduced as it is, the polymer electrolyte will be completely overdried, and the polymer electrolyte fuel cell may stall. While watching the situation for a while, if the impedance Z gradually recovers and the load current I = small and the impedance Z = small, the control of ΔP = small may be performed at that point.

Therefore, the required water vapor amount H may be calculated from the impedance Z and the load current I according to such a logic. Specifically, load current I = large and impedance Z = large → H =
Large, load current I = small, and impedance Z = small → H =
Small, load current I = large and impedance Z = small → H = not changed Load current I = small and impedance Z = large → H = not changed, showing impedance Z, load current I and It is calculated using a three-dimensional map having the required water vapor amount H as three axes.

According to the ninth embodiment having such a construction, the hydrogen gas can be humidified more accurately, and the polymer electrolyte fuel cell can be controlled with high accuracy.

Although the fifth to ninth embodiments have been described focusing only on the anode gas system, that is, the hydrogen gas system, the oxygen-containing gas humidifier can be adjusted by increasing or decreasing the number of revolutions of the pump 500. Since the water pressure Pw on the 120 side is also adjusted at the same time, the cathode side gas system, that is, the oxygen-containing gas system can have an appropriate amount of humidification as in the hydrogen gas system.

Further, in the fifth to ninth embodiments, the pump 5 determines the pressure difference ΔP between the water pressure Pw and the hydrogen gas pressure Ph.
It was adjusted by changing the rotation speed of 00, but blower 5
The hydrogen gas pressure Ph may be adjusted by changing the amount of pressurization of 50. Further, a configuration in which the rotation speed of the pump 500 and the pressurization amount of the blower 550 are both changed is also suitable. Further, in the above-described embodiment, the humidification amount of the oxygen-containing gas is adjusted according to the adjustment of the humidification amount of hydrogen gas. However, by adjusting the pressurization amount of the blower 590, It is also preferable to adjust independently.

The tenth embodiment of the present invention will be described below. When the polymer electrolyte fuel cell becomes large, even the humidifying unit 200 cannot humidify a necessary amount of humidification with one plate, so that a plurality of humidifying plates are connected in parallel,
It is necessary to secure the amount of humidification. Generally, for 5 to 10 cells of the polymer electrolyte fuel cell stack,
Since one plate of the humidifying unit is required, the number of cells in a large polymer electrolyte fuel cell stack with an output of several kW to several tens of kW is several hundred, and therefore the number of humidifying plates is large. Will reach dozens.

In such a large-scale humidification system, if it is attempted to control the amount of humidification for all the humidification plates at the same time, it is necessary to control the water pressurizing pump having a large capacity. In particular, in a system (also called a solid polymer fuel cell hybrid system) in which a polymer electrolyte fuel cell and a secondary battery (for example, a lead battery) are combined, a large load fluctuation or a short-term load fluctuation causes a secondary load fluctuation. Since it can be absorbed by the cell, the fuel cell itself can be operated under relatively constant operating conditions. Therefore, for this purpose, as shown in FIG. 15, in this humidifying system 2000, while supplying water with a large water pressurizing pump 2010 as a whole system, some of the humidifying units 2100 have a small size. The water pressurizing pump 2020 is used to start the small water pressurizing pump 2020 so as to actuate the fluctuation of the humidification amount due to the load fluctuation of the polymer electrolyte fuel cell (power generation unit 100).

According to the tenth embodiment, the responsiveness of pressurization is improved and the power consumption of the entire water pressurizing pump can be reduced. In addition, in FIG. 15, in order to explain the system configuration in an easy-to-understand manner, the humidifying units 2100 and 220
Although 0 and 2300 are written as independent, it is preferable that the humidifying units 2100 to 2300 are integrated and thermally coupled to each other. Therefore, as in the first embodiment, the cooling water used in the power generation unit 100 is also supplied to the humidification units 2100 to 2300 to generate the power generation unit 100.
It is desirable to transfer the heat generated in step 1 to the humidifying part.

The eleventh embodiment of the present invention will be described below. In a polymer electrolyte fuel cell mounted on an automobile, it is necessary to quickly lower the temperature T of the polymer electrolyte fuel cell when stopped. Therefore, in the eleventh embodiment, a configuration for lowering the temperature T of the fuel cell by using the humidifying unit 200 described so far is shown.

The humidification controller of the eleventh embodiment is the fifth embodiment.
It has the same hardware and software configuration as the fuel cell system as an example. Further, the humidification control device of this embodiment also executes a stop control routine shown in FIG. 16 as a control process executed by the electronic control unit 1200. Hereinafter, this stop control routine will be described in detail. This stop control routine is stored in the ROM 1220 in the form of a program, and the power generation unit 100
After the operation is started, the operation is performed every predetermined time (for example, every 50 msec).

When this stop control routine is executed, the CPU 1210 first determines whether or not the power generation unit 100 is stopped (step S200). This determination is made based on, for example, whether or not a command to stop the load is received from the load side. If it is determined that the power generation unit 100 is stopped, the polymer electrolyte fuel cell (power generation unit 100) is stopped (step S210).
The process of stopping the polymer electrolyte fuel cell includes a process of cooling the power generation unit 100 by a general method, and further, the pressure of the material gas (hydrogen gas and oxygen-containing gas) is reduced. Processing is also included.

Then, a control signal is output to the electric motor 500a of the pump 500 provided in the water passage 510 to maintain the pressure of the pump 500 in the current state (step S2).
20). Although the hydrogen gas pressure Ph (and the oxygen-containing gas pressure) is lowered in step S210, step S22
Since the water pressure Pw becomes a constant pressure due to 0, as a result, the pressure difference ΔP acting on the porous membrane 111 becomes a large pressure difference equal to or larger than a predetermined pressure, passes through the porous membrane 111, and flows from the water channel 115p to the gas flow. The amount of humidifying water flowing into the passage 113p is increased. As a result, a large amount of water is supplied to the inside of the power generation unit 100, and due to the heat of vaporization of this water,
The power generation unit 100 is further cooled.

After execution of step S220, it is determined whether or not a predetermined time has elapsed (step S230), and the process of step S220 is repeated until the time has elapsed, and cooling of the power generation unit 100 is continued. When the predetermined time has elapsed, the processing of this stop control routine is temporarily terminated.

As described in detail above, according to the eleventh embodiment, when the power generation unit 100 is stopped, the hydrogen gas humidifier 110 and the oxygen-containing gas humidifier 120 are used to supply hydrogen gas and oxygen-containing gas. Actively increase the amount of humidification. For this reason, the increased heat of vaporization of water can quickly cool the power generation unit 100.

In this embodiment, the amount of humidification may be increased by positively increasing the water pressure Pw to make the pressure difference ΔP a large pressure difference equal to or larger than a predetermined pressure. In addition, in this embodiment, both the anode gas system and the cathode gas system are targeted for humidification, but either the cathode gas system or the cathode gas system may be targeted for humidification.

In the eleventh embodiment, the processing when the power generation unit 100 is normally stopped is described, but the following processing is performed when the power is stopped urgently.

The emergency here means when the temperature of the polymer electrolyte fuel cell abnormally rises (when the cooling system does not function and thermal runaway occurs). When the polymer electrolyte fuel cell undergoes thermal runaway, it is necessary to immediately cut off the gas system and the electric system (electric system to the load). Even if these are immediately cut off, the polymer electrolyte fuel cell stack itself Due to the heat capacity, it is difficult to immediately reduce the temperature of the stack (battery temperature).

The method of dealing with this emergency differs depending on the control method of the gas system at the time of emergency shutdown of the polymer electrolyte fuel cell. When the valve of the gas system is closed at the time of an emergency stop and the control is performed so that the gas is trapped in a state where the emergency stop is activated, the water pressure Pw is increased to increase the pressure difference ΔP and to increase the porosity. The amount of humidifying water that passes through the membrane 111 and flows into the gas flow passage 113p from the water flow passage 115p is increased.

On the other hand, in the case of performing control such that the gas is released from the safety valve of the gas system (exhaust to the exhaust system) at the time of emergency stop and the gas is released to the atmospheric pressure, the solid polymer fuel cell With the emergency stop, the pressure of the gas is lowered, but at this time, the pressurization pressure of the water pump for the humidifying water is maintained without being lowered (the method of the 11th embodiment).

In this way, even when the power generation unit 100 is in an emergency stop, the power generation unit 100 can be cooled more quickly.

Still another embodiment will be described. In the fifth to eleventh embodiments described above, the hydrogen gas humidifier 11 is used.
0 and the oxygen-containing gas humidifier 120 were used to adjust the humidification of the material gas supplied to the power generation unit 100. Instead, the bypass flow bypassing the hydrogen gas humidifier 110 (and the oxygen-containing gas humidifier 120) is used. A passage is provided, and the humidifier for dry gas and hydrogen gas passing through this bypass passage 11
By adjusting the mixing ratio with the humidified gas from 0,
It may be configured to control humidification of the material gas.

Another embodiment of the humidifier of the fuel cell will be described below. In a conventional humidifier using a membrane filter (filtration membrane), the amount of humidification is too large, so the humidification area (both gas and water flow) to supply the required amount of humidification to the polymer electrolyte fuel cell stack. The area in contact with the road) may be small. However, in such a small area, even when trying to change the liquid water that has passed from the water flow path side to the gas flow path side to the gaseous water, since a relatively large amount of liquid water exists in a small area, Even if the heat generated by the fuel cell stack is transferred, it cannot be easily vaporized. In this state, when gas is flowing in the gas flow path, liquid water is blown off by the gas and scattered, and is supplied to the gas inlet of the fuel cell stack in the state of water droplets, not in the required state of water vapor. I will end up.

The humidifying device of the embodiments described below has a structure for vaporizing this water into a steam state even in the presence of a relatively large amount of water in a small humidifying area. FIG. 17 is a structural diagram showing a part of the structure of the gas humidifier of the twelfth embodiment as the humidifier for such a fuel cell. Note that (A) in FIG. 17 is A-A in (B).
It is a line sectional view. 17B is a sectional view taken along the line BB of FIG.

As shown in FIG. 17, a gas humidifier 3000.
Is a plurality (only one is shown in the figure) of the porous membranes 3100 and the plate 31 that holds the porous membranes 3100 from the side.
10, a central layer corresponding to the porous membrane 111 of the first embodiment is formed, and the central layer is sandwiched by the same separators 3113 and 3115 as in the first embodiment, so that the gas flow path 3 is formed.
113p and 3115p are formed. Further, a second porous film 3200, which is more porous than the porous film 3100 (hereinafter referred to as the first porous film), is provided between the central layer and the separator 3113 on the gas flow channel 3113p side.

As the first porous membrane 3100, a hydrophilic fluorine-based microfiltration membrane having a pore size of 1 micron, a porosity of 83% and a thickness of 35 microns is used. As the second porous film 3200, a porous carbon plate having a pore diameter of 55 μm, a porosity of 55% and a thickness of 2 mm is used. As the plate 3020, a dense carbon plate having excellent thermal conductivity is used.

In the gas humidifier 3000 thus constructed, the water (humidifying water) which has passed through the first porous membrane 3100 from the water flow passage 3115p side to the gas flow passage 3113p side has the first porous membrane 3100 and the second porous membrane 3100. It is deposited at the interface of the film 3200. The water deposited on the interface permeates into the second porous membrane 3200 and spreads over the entire second porous membrane 3200, and is vaporized into gas from the gas flow channel side surface of the second porous membrane 3200. Go. Since the second porous film 3200 has a larger area than the first porous film 3100, heat is not locally taken away due to vaporization, and the second porous film 32
00 can be vaporized into the gas from the gas flow path side surface.

Therefore, when a hydrophilic fluorine-based microfiltration membrane having a pore size of 1 micron, a porosity of 83%, and a thickness of 35 microns is used as the first porous membrane 3100, by combining it with the second porous membrane 3200, Water can be vaporized to a good water vapor state. Therefore, it is possible to prevent the anode of the fuel cell, which is the destination of the hydrogen gas, from getting too wet,
It is possible to prevent the output of the fuel cell from decreasing.

The second porous membrane 3200 is provided on the entire surface of the center layer on the side of the separator 3115. Instead, however, the second porous membrane 3200 is provided downstream of each of the first porous membranes 3100 to the gas channel 3113p. The configuration may be limited to a certain range toward the side. Also with this configuration, since the second porous membrane 3200 has a larger area than the first porous membrane 3100, heat is not locally taken away due to vaporization, and the gas flow of the second porous membrane 3200 is reduced. Vaporization from the roadside surface can be promoted.

The thirteenth embodiment will be described below. FIG.
FIG. 8 is an explanatory view showing the structure of a part of the gas humidifier of the thirteenth embodiment. In addition, (a) of FIG. 18 is C- of (b).
It is a C line sectional view. 18B is the DD of FIG.
It is a line sectional view.

As shown in FIG. 18, the gas humidifier 4000 of the thirteenth embodiment is the same as the gas humidifier 30 of the twelfth embodiment.
Compared with No. 00, the configuration of the second porous membrane 3200 is different, and other configurations are the same (the same parts are denoted by the same numbers as in the twelfth embodiment). That is, in the gas humidifier 3000 of the twelfth embodiment, the second porous film 3200 is used.
On the other hand, in the gas humidifier 400 of this embodiment, the gas flow passage 3113p itself is the second porous membrane 4200, whereas the gas flow passage is above the above.

The second porous film 4200 is not filled over the entire area of the gas flow channel 3113p, but is in a constant range from each first porous film 3100 toward the downstream side of the gas flow path 3113p. It is filled only. The second porous film 4200 is more porous than the porous film 3111 provided on the gas flow channel 3113p side, and is more porous than the second porous film 3200 of the twelfth embodiment described above. It is of quality. Specifically, the second porous membrane 4200 has a pore diameter of 1.5 mm and a porosity of 95.
% Foamed nickel plate is used.

In the gas humidifier 4000 thus constructed, the water (humidifying water) deposited on the gas channel side of the first porous membrane 3100 is blown off by the gas and adheres to the second porous membrane 4200. . Since the second porous membrane 4200 is installed on the downstream side of the gas flow including the point where water is deposited, the water spreads throughout the second porous membrane 4200, and Is vaporized into irregularly flowing (turbulent) gas. Second porous membrane 420
0 has a larger area than the first porous membrane 3100,
The heat is not locally absorbed due to the vaporization, and the vapor can be vaporized into the gas inside the second porous film 4200.

Therefore, in the gas humidifier 4000 of the thirteenth embodiment, as in the twelfth embodiment, water can be vaporized into a good water vapor state, and the fuel cell of the hydrogen gas supply destination can be used. By preventing the anode from getting too wet, it is possible to prevent the output of the fuel cell from decreasing.

Incidentally, the gas humidifier 40 of the thirteenth embodiment
00, as shown in FIG.
An electric heater 4500 for heating may be incorporated inside the separator 3113 forming p. 19, (a) is a sectional view taken along line EE of (b),
(B) is the FF sectional view taken on the line of (A). With this configuration, vaporization of water that has passed through the first porous membrane 3100 from the water flow channel 3115p side to the gas flow channel 3113p side can be assisted by heat generation of the electric heater. Therefore, water can be vaporized into a more preferable state of water vapor. As a result of the promotion of vaporization, the volume of the second porous membrane 4200 can be made smaller than that of the configuration of the thirteenth embodiment, and as a result, the humidifier can be further downsized. Play.

Further, in the structure using the electric heater 4500, the water droplet state on the downstream side of the second porous film 4200 may be detected and the electric heater 4500 may be turned on / off in accordance with the detection result. Good. With this configuration, more accurate humidification can be performed.

The embodiments of the present invention have been described above.
The present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various modes without departing from the scope of the present invention.

[0143]

As described above, in the humidifier for a fuel cell of the present invention, since the porous membrane has hydrophilicity, water that has permeated through the porous membrane is easily vaporized,
Water can be included in the material gas in the state of good water vapor, not in the state of water droplets. For this reason, it is possible to prevent the electrode of the fuel cell, which is the supply destination of the material gas, from becoming too wet and the output of the fuel cell from decreasing.

If the pore size is narrowed with silicone, the amount of water that permeates from the porous membrane can be adjusted to a small amount. Therefore, the amount of humidification is too large to use as it is. Can be used even.

If the porous membrane is bent and arranged three-dimensionally, it is possible to realize a larger amount of humidification with a humidifier having a small volume and to make the apparatus compact.

According to the humidification control device for a fuel cell of the present invention described above, the amount of water that permeates the porous membrane can be ideally determined according to the operating state of the fuel cell. For this reason, the material gas supplied to the fuel cell can be properly humidified.

The operation state of the fuel cell depends on the temperature of the fuel cell, the impedance of the fuel cell, the flow rate of the material gas discharged from the fuel cell, and the load current of the fuel cell. For example, the material gas supplied to the fuel cell can be properly humidified according to these parameters.

According to the humidification control device of the tenth aspect,
When the fuel cell is stopped, the pressure difference between the water in contact with the porous membrane and the material gas becomes a large pressure difference, and the amount of water that passes through the porous membrane and flows from the water channel to the material gas channel is Will be increased. As a result, a large amount of water is supplied into the fuel cell, and the heat of vaporization of the water can cool the fuel cell. That is, when the fuel cell is stopped,
Using this humidification control device, the fuel cell can be cooled immediately.

In the method of manufacturing the humidifying device of the present invention, a part of the silicone adhesive can be left on the surface and inside of the porous film. Therefore, the porous membrane has a large number of pores whose pore diameter is narrowed by silicone, and as a result, the amount of water permeating from the porous membrane can be adjusted to be small.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fuel cell stack as a first embodiment to which a humidifying device for a fuel cell according to the present invention is applied.

FIG. 2 is a structural diagram of a cell of a fuel cell.

FIG. 3 is a structural diagram of a hydrogen gas humidifier 110.

FIG. 4 is a graph showing a correlation between a pressure difference ΔP and a humidification amount in a porous film 111.

FIG. 5 is a structural diagram of a humidifier 600 for a fuel cell according to a second embodiment.

FIG. 6 is a structural diagram of a humidifier 700 of a fuel cell according to a third embodiment.

FIG. 7 is a structural diagram of a humidifier 800 for a fuel cell according to a fourth embodiment.

FIG. 8 is a schematic configuration diagram of a fuel cell system as a fifth embodiment to which the humidification control device for a fuel cell of the present invention is applied.

FIG. 9 is an electronic control unit 12 of the fuel cell system.
10 is a flowchart showing a pressure difference control routine executed by No. 00.

FIG. 10 is a graph showing the correlation between the temperature T of the fuel cell and the required water vapor amount H.

FIG. 11 is a graph showing the correlation between the required water vapor amount H and the set pressure difference ΔPset.

FIG. 12 is a graph showing the correlation between the impedance Z and the required water vapor amount H used in the sixth embodiment.

FIG. 13 is a graph showing the correlation between the gas flow rate M and the required water vapor amount H used in the seventh example.

FIG. 14 is a graph showing the correlation between the load current I and the required water vapor amount H used in the eighth embodiment.

FIG. 15 is a schematic configuration diagram showing a humidification system for a fuel cell as a tenth embodiment.

FIG. 16 is a flowchart showing a stop control routine executed by the electronic control unit in the eleventh embodiment.

FIG. 17 is a structural diagram showing a partial structure of a gas humidifier 3000 of the twelfth embodiment.

FIG. 18 is a structural diagram showing a partial structure of a gas humidifier 4000 of the thirteenth embodiment.

FIG. 19 is a structural diagram of a modified example of the thirteenth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 10 ... Cell 11 ... Electrolyte membrane 12 ... Cathode 13 ... Anode 14 ... Separator 14p ... Oxygen gas channel 15 ... Separator 15p ... Hydrogen gas channel 20, 30 ... Cooling water channel 20 ... Cooling water channel 40, 50 ... Current collecting plate 60, 70 ... Insulating plate 100 ... Power generation unit 110 ... Hydrogen gas humidifier 111 ... Porous membrane 113 ... Separator 113p ... Gas channel 113p ... Hydrogen gas channel 115 ... Separator 115p ... Water channel 116, 117 O-ring 118, 119 ... Sealing member 120 ... Oxygen-containing gas humidifier 121 ... Porous membrane 123, 125 ... Separator 123p ... Oxygen gas flow path 125p ... Water flow path 200 ... Humidification unit 300 ... End plate 310 ... End plate 312, 314 ... Bolt 320 ... Third end plate 322 324 ... Volt 400 ... Gas humidifier 500 ... Pump 500a ... Electric motor 510 ... Water passage 520 ... Water passage 530 ... Water passage 540 ... Hydrogen gas passage 550 ... Blower 560 ... Hydrogen gas passage 570 ... Hydrogen gas passage 580 ... Oxygen gas passage 590 ... Blower 592 ... Oxygen gas passage 594 ... Oxygen gas passage 600 ... Humidifier 602 ... Porous membrane 604, 606 ... Separator 608, 610 ... Sheet 612-615 ... Seal member 700 ... Humidifier 702 ... Porous membrane 800 ... Humidifier 802 ... Porous membrane 804 ... Water channel 806 ... Film 808, 810 ... Separator 808p, 810p ... Channel 1100 ... Control system 1105 ... Temperature sensor 1110 ... First pressure sensor 1120 ... Second pressure sensor 1200 ... Electronic control unit 1210 ... CPU 1220 ... ROM 1230 ... RAM 1240 ... Input interface 1250 ... Output interface 2000 ... Humidification system 2010 ... Water pressurizing pump 2020 ... Water pressurizing pump 2100-2300 ... Humidifying unit 3000 ... Gas humidifier 3020 ... Plate 3100 ... First porous membrane 3110 ... Plate 3113 ... Separator 3113p ... Gas flow path 3115 ... Separator 3115p ... Water flow path 3200 ... Second porous membrane 4000 ... Gas humidifier 4200 ... Second porous membrane 4500 ... Electric heater C1 ... Circulation path C2 ... Circulation path H ... Necessary Water vapor amount I ... Load current M ... Gas flow rate Ph ... Hydrogen gas pressure Pw ... Water pressure T ... Temperature Z ... Impedance ΔP ... Pressure difference

Claims (11)

[Claims] 1. A humidifier for humidifying a material gas to be supplied to an electrode of a fuel cell, the humidifier being in contact with a water flow path and the material gas flow path, and depending on a pressure difference between the water and the material gas. A humidifier for a fuel cell, which comprises a porous membrane that permeates the water, and the porous membrane has hydrophilicity. 2. The porous membrane has a diameter of 10 ⁻⁸ m to 1
0 ^-7 polyolefin having a large number of m holes (C _n H _2n)
The humidifying device for a fuel cell according to claim 1, which is a resin film. 3. The humidifier for a fuel cell according to claim 1, wherein the porous membrane has a large number of pores whose pore diameter is narrowed by silicone. 4. The humidifying device for a fuel cell according to claim 1, wherein the porous membrane is bent and arranged three-dimensionally. 5. A humidification control device for controlling the amount of humidification of a material gas supplied to an electrode of a fuel cell, the device being in contact with a water flow path and the material gas flow path, A porous membrane that permeates the water according to a pressure difference, a water pressure detection unit that detects the water pressure of the water channel, a gas pressure detection unit that detects the gas pressure of the material gas channel, and the fuel. An operating state detecting means for detecting an operating state of the cell; a necessary water vapor amount calculating means for calculating a required water vapor amount in the material gas required by the fuel cell from the detected operating state of the fuel cell; Based on the ideal pressure difference calculating means for calculating the ideal pressure difference between the water and the material gas from the required amount of water vapor, and the water pressure detected by the water pressure detecting means and the gas pressure detected by the gas pressure detecting means, The pressure difference between the water and the material gas is the ideal The fuel cell humidification control and control means for controlling at least one of the water pressure or the gas pressure so that the force difference. 6. The operating state detecting means includes a temperature detecting means for detecting the temperature of the fuel cell.
A humidification control device for a fuel cell as described above. 7. The humidification control device for a fuel cell according to claim 5, wherein the operating state detection means includes impedance detection means for detecting the impedance of the fuel cell. 8. The humidification control device for a fuel cell according to claim 5, wherein the operating state detecting means includes a gas flow rate detecting means for detecting a flow rate of the material gas discharged from the fuel cell. 9. The humidification control device for a fuel cell according to claim 5, wherein the operating state detecting means includes a current detecting means for detecting a load current of the fuel cell. 10. The humidification control device for a fuel cell according to claim 5, further comprising a stop time determination means for determining a stop time of the fuel cell, and the water and the material when the stop time is determined. A humidification control device for a fuel cell, comprising: a stop control means for controlling at least one of the water pressure and the gas pressure so that the pressure difference between the gas and the gas becomes a large pressure difference equal to or larger than a predetermined pressure difference. 11. A method of manufacturing a humidifier for a fuel cell according to claim 3, wherein a step of diluting the silicone adhesive with an organic solvent, and a step of diluting the silicone adhesive solution with the porous membrane. And a step of filtering under pressure, the method of manufacturing a humidifier.