JPH10255828A - Fuel cell and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain supply gas in an optimal humidifying condition, and prevent the deterioration of fuel cell performance by controlling a pure water injecting means on the basis of signals from a supply gas flow rate detecting means, a supply gas temperature detecting means, a pure water temperature detecting means, a fuel cell load detecting means and a fuel cell internal temperature detecting means. SOLUTION: A gas flow rate correction value is read in on the basis of a supply gas flow rate detected through a supply gas flow rate detecting means 16, and a basic pure water injection quantity is set in response to the gas flow rate correction value. An operation is performed on an actual pure water injection quantity by multiplying the basic pure water injection quantity by a gas temperature correction value, a fuel cell temperature correction value and a fuel cell load correction value. Pure water set to a pure water injection quantity is injected into supply gas in a gas supply passage 14 from a pure water injecting means 20, and it is humidified. Therefore, a humidifying quantity according to an operating condition of a fuel cell main body 12 is controlled by adding a flow rate and a temperature of the supply gas, and optimal fuel cell output is obtained from the fuel cell main body 12, and drying of an electrolyte film by lack of humidification can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fuel cell for supplying a humidified supply gas into a fuel cell body and a control method thereof.

[0002]

2. Description of the Related Art For example, a fuel cell has been developed in which a plurality of fuel cell structures each having an anode electrode and a cathode electrode opposed to each other with a solid polymer electrolyte membrane interposed therebetween are sandwiched by a separator and stacked. Are being put to practical use for various applications.

In this type of fuel cell, for example, hydrogen gas (fuel gas) is supplied to an anode side electrode and oxidizing gas (air) is supplied to a cathode side electrode, so that the hydrogen gas is ionized. It is configured such that it flows through the solid polymer electrolyte membrane, thereby obtaining electric energy outside.

In this case, in the fuel cell, it is necessary to maintain the solid polymer electrolyte membrane in a desired humidified state in order to exhibit an effective power generation function. For this reason, humidification of a supply gas which is a hydrogen gas or an oxidizing gas is performed. For example, a supply gas humidifier disclosed in Japanese Patent Application Laid-Open No. Hei 7-263010 is known.

In the above prior art, a signal from a load detecting means for detecting a load of a fuel cell is received, and an amount of pure water corresponding to a required water amount of the fuel cell is determined by a gas supplied to the fuel cell. While supplying to the supply passage, receiving a signal from temperature detecting means for detecting the internal temperature of the fuel cell,
The heating unit provided in the pure water supply passage is controlled so that the temperature of the pure water becomes substantially equal to the internal temperature of the fuel cell. That is, in the above-described related art, the load and the internal temperature of the fuel cell are detected, and the amount and the temperature of the pure water supplied to the gas supply passage are controlled.

[0006]

However, in the above prior art, since the humidification state of the supply gas is adjusted based on the load and the internal temperature of the fuel cell, a response delay tends to occur with time. As a result, there is a possibility that an optimum humidification amount cannot be ensured particularly in a transitional period, a desired battery output cannot be obtained, and a humidification amount is insufficient and the electrolyte membrane may be dried. That is, even if the flow rate of the supply gas is increased, if the amount of pure water injected into the supply gas is not changed, an optimal humidification amount cannot be obtained, and the electrolyte membrane is dried and the battery is dried. It has been pointed out that the output is greatly reduced.

The present invention solves this kind of problem and provides a fuel that can optimally humidify a supply gas according to the operating state of a fuel cell and can reliably obtain a desired cell output. It is an object to provide a battery and a control method thereof.

[0008]

In order to solve the above-mentioned problems, a fuel cell and a control method thereof according to the present invention include:
Supply gas supplied to the fuel cell body by controlling the pure water injection means based on detection signals from the supply gas flow rate detection means, the pure water temperature detection means, the battery load detection means and the battery internal temperature detection means Is controlled.
Therefore, optimal supply gas humidification control according to the operating condition of the fuel cell is performed without causing a time response delay or the like. As a result, a decrease in the battery output due to an insufficient humidification amount and the drying of the electrolyte membrane can be prevented as much as possible, and an effective battery output can be always obtained.

Further, a detection signal from the supply gas temperature detection means is added to control the pure water injection means. For this reason,
In addition to preventing the formation of dew in the gas supply passage, when the temperature of the supply gas increases, the battery output does not decrease due to insufficient humidification of the supply gas.

[0010]

FIG. 1 is a schematic configuration diagram of a fuel cell 10 according to a first embodiment of the present invention.

The fuel cell 10 includes a fuel cell main body 12, a gas supply passage 14 for supplying a supply gas (fuel gas / oxidant gas) to the fuel cell main body 12, and a gas supply passage 14.
Supply gas flow rate detecting means 16 for detecting the flow rate of the supply gas flowing through the supply gas, supply gas temperature detection means 18 for detecting the temperature of the supply gas flowing through the gas supply passage 14, and the supply gas flowing through the gas supply passage 14. A pure water injection means 20 for supplying pure water to the water; a pure water temperature detection means 22 for detecting a temperature of the pure water supplied to the pure water injection means 20;
A battery load detecting means 24 for detecting a battery load of the fuel cell main body 12, a battery internal temperature detecting means 26 for detecting a temperature inside the fuel cell main body 12, and a control unit (control means for controlling the driving of the fuel cell 10) ) 28.

The control unit 28 includes, for example, a CPU, an R
It is composed of a microcomputer having an OM and a RAM, and includes a supply gas flow rate detection means 16, a supply gas temperature detection means 18, a pure water temperature detection means 22, a battery load detection means 24
And a function of controlling the pure water injection means 20 based on a signal from the battery internal temperature detection means 26.

The fuel cell body 12 has a fuel cell structure 3 in which an air electrode (cathode side electrode) 32 and a hydrogen electrode (anode side electrode) 34 are opposed to each other with a solid polymer electrolyte membrane 30 interposed therebetween.
6 is provided. The fuel cell structure 36 is formed by laminating a plurality of the fuel cell structures 36 via a separator (not shown), thereby forming the fuel cell main body 12.

The operation of the fuel cell 10 configured as described above will be described below in relation to the control method according to the present invention.

First, the relationship between the flow rate of the supply gas and the humidification amount is shown in FIG. 2A. As the flow rate of the supply gas increases, the humidification amount of the electrolyte membrane 30 constituting the fuel cell body 12 decreases. There is a tendency. Therefore, as shown in FIG. 2B, the relationship between the flow rate of the supply gas and the pure water injection amount is set.

On the other hand, as shown in FIG. 3, a correction table of the gas flow rate correction value corresponding to the change of the supply gas flow rate is set in advance. Other correction tables include a supply gas temperature correction value corresponding to the supply gas temperature (see FIG. 4), a pure water temperature correction value for the pure water temperature (see FIG. 5), and a battery temperature correction value for the battery temperature (see FIG. 6). , And a battery load correction value (see FIG. 7) corresponding to the battery load.

The operation of the fuel cell 10 will now be described with reference to the flowchart shown in FIG. First, when the supply gas is supplied to the gas supply passage 14, the flow rate of the supply gas flowing through the gas supply passage 14 is detected via the supply gas flow detection means 16 (step ST1). Further, when it is determined in step ST2 that the supply gas is flowing through the gas supply passage 14 (in step ST2,
YES), the process proceeds to step ST3, and the gas flow rate correction value is read.

A basic pure water injection amount Tiw as shown in FIG. 9 (b) is set from the gas flow rate correction value shown in FIG. 3 and the pure water injection amount shown in FIG. 2B, and is read in step ST3. The basic pure water injection amount Tiw is read based on the obtained gas flow correction value (step ST4).

Next, the temperature of the supply gas flowing through the gas supply passage 14 is detected by the supply gas temperature detecting means 18 (step ST5). As shown in FIG. 4, a gas temperature correction value Tgf is read based on the detected supply gas temperature (step ST6). Pure water is supplied to the supply gas in the gas supply passage 14 via the pure water injection means 20, and the temperature of the pure water is detected by the pure water temperature detection means 22.
And the pure water temperature correction value T as shown in FIG.
wf is read (step ST7, step ST7).
8).

The supply gas humidified by the pure water is supplied into the fuel cell main body 12, and oxygen gas or air is supplied to the air electrode 32 constituting each fuel cell structure 36, while hydrogen gas is supplied to the hydrogen electrode 34. Gas is supplied and power is generated.

The internal temperature of the fuel cell main body 12 is detected via the cell internal temperature detecting means 26 (step ST9),
As shown in FIG. 6, a battery temperature correction value Tfcf is read based on the detected battery temperature (step ST10). Further, the battery load of the fuel cell body 12 is detected by the battery load detecting means 24 (step ST1).
1) As shown in FIG. 7, a battery load correction value Tfcff corresponding to the detected battery load is read (step ST12).

Then, the process proceeds to step ST13, where the actual pure water injection amount is calculated based on the basic pure water injection amount Tiw, the gas temperature correction value Tgf, the pure water temperature correction value Twf, the battery temperature correction value Tfcf, and the battery load correction value Tfcff. Injection amount Tiwf
Is calculated. Then, the pure water injection means 20 is controlled, and the pure water set to the calculated pure water injection amount Tiwf is injected into the supply gas flowing through the gas supply passage 14 (step ST14).

In this case, in the first embodiment, first, a gas flow rate correction value is read based on the supply gas flow rate detected by the supply gas flow rate detection means 16, and the gas flow rate correction value is read in accordance with the gas flow rate correction value. The basic pure water injection amount Tiw is set. Next, the gas temperature correction value Tg is added to the basic pure water injection amount Tiw.
f (if necessary), the pure water temperature correction value Twf, the battery temperature correction value Tfcf, and the battery load correction value Tfcff are multiplied to calculate the actual pure water injection amount Tiwf. Then, the pure water set to the pure water injection amount Tiwf is injected into the supply gas in the gas supply passage 14 and humidified.

For this reason, the humidification amount control in accordance with the operating condition of the fuel cell main body 12 is performed in consideration of the flow rate and the temperature of the supply gas. For example, only the internal temperature of the fuel cell main body 12 is detected. In comparison, there is no time delay in response. As a result, an optimal cell output can be obtained from the fuel cell main body 12, and the electrolyte membrane 3
An effect is obtained that it is possible to reliably avoid problems such as drying due to insufficient humidification.

FIG. 9 shows the effect of the gas flow rate correction value alone, FIG. 10 shows the effect of the gas temperature correction value only, and FIG. The effect of only the temperature correction value is shown.

That is, in FIG. 9, a gas flow rate correction value is set based on the gas flow rate (see (a) in FIG. 9), and the basic pure water injection amount Tiw is changed based on the gas flow rate correction value. (See (b) in FIG. 9). Then, by injecting the basic pure water injection amount Tiw into the supply gas as the pure water injection amount Tiwf, the effect of effectively increasing the battery output with an increase in the gas flow rate is obtained ((c) in FIG. 9). )
reference). Therefore, when the flow rate of the supply gas becomes large,
It is possible to reliably prevent the battery output from lowering due to the drying of the electrolyte membrane 30.

In FIG. 10, a gas temperature correction value Tgf is read corresponding to the supply gas temperature (see (a) in FIG. 10), and the pure water injection amount Tiwf is changed based on the gas temperature correction value Tgf. (See (b) in FIG. 10). Here, if a large amount of pure water is injected when the temperature of the supply gas is low, dew condensation occurs in the gas supply passage 14. Therefore, when the supply gas temperature is low, the pure water injection amount Tiwf is kept low. On the other hand, when the temperature of the supply gas becomes high, the pure water injection amount Tiwf
Set many. This makes it possible to secure an optimal humidification amount and improve the battery output (see FIG. 10,
(C)).

In FIG. 11, a pure water temperature correction value Twf is read according to the pure water temperature, and a pure water injection amount Tiwf is read based on the pure water temperature correction value Twf (FIG. 11).
Medium, (a) and (b)). Here, if a large amount of pure water is injected when the temperature of the pure water is low, the temperature of the supply gas in the gas supply passage 14 decreases, and dew condensation occurs. For this reason,
When the pure water temperature is low, the pure water injection amount Tiwf is kept low. On the other hand, when the temperature of the pure water increases, the humidification amount tends to be insufficient, and the pure water injection amount Tiwf is increased in accordance with the pure water temperature. Thereby, it is possible to always secure the optimal humidification amount and improve the battery output (see (c) in FIG. 11).

FIG. 12 is a schematic structural explanatory view of a fuel cell 60 according to a second embodiment of the present invention.

The fuel cell 60 includes a humidifying section 62
The humidifying section 60 is integrally attached to the fuel cell main body 64. Note that the same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the fuel cell 60 configured as described above,
Similar to the fuel cell 10 according to the first embodiment, effects such as an optimum humidification amount control according to the operation state of the fuel cell main body 64 can be obtained.

[0032]

As described above, in the fuel cell and the control method thereof according to the present invention, the supply gas flow rate detection means, the supply gas temperature detection means (if necessary), the pure water temperature detection means,
Since the pure water injection unit is controlled based on the signals from the battery load detection unit and the battery internal temperature detection unit, the supply gas can be maintained in an optimal humidified state. As a result, it is possible to effectively prevent a decrease in battery performance, drying of the electrolyte membrane, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view of a fuel cell according to a first embodiment of the present invention.

FIG. 2A is a relationship diagram between a supply gas flow rate and a humidification amount, and FIG. 2B is a relationship diagram between a supply gas flow rate and a pure water injection amount.

FIG. 3 is a correction table of a supply gas flow rate and a gas flow rate correction value.

FIG. 4 is a correction table of a supply gas temperature and a gas temperature correction value.

FIG. 5 is a correction table of a pure water temperature and a pure water temperature correction value.

FIG. 6 is a correction table of a battery temperature and a battery temperature correction value.

FIG. 7 is a correction table of a battery load and a battery load correction value.

FIG. 8 is a flowchart illustrating an operation of the fuel cell.

FIG. 9 is an explanatory diagram of an effect by a gas flow rate correction value.

FIG. 10 is an explanatory diagram of an effect by a gas temperature correction value.

FIG. 11 is an explanatory diagram of an effect of a pure water temperature correction value.

FIG. 12 is a schematic structural explanatory view of a fuel cell according to a second embodiment of the present invention.

[Explanation of symbols]

10, 60 ... fuel cell 12, 64 ... fuel cell body 14 ... gas supply passage 16 ... supply gas flow rate detection means 18 ... supply gas temperature detection means 20 ... pure water injection means 22 ... pure water temperature detection means 24 ... battery load detection Means 26 ... Battery internal temperature detecting means 28 ... Control unit 30 ... Electrolyte membrane 32 ... Air electrode 34 ... Hydrogen electrode 36 ... Fuel cell structure 62 ... Humidification section

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[Procedure amendment]

[Submission date] June 23, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 8

[Correction method] Change

[Correction contents]

FIG. 8

Claims (5)

[Claims] A fuel cell body incorporating a fuel cell structure having an anode electrode and a cathode electrode opposed to each other with an electrolyte membrane interposed therebetween; a gas supply passage for sending a supply gas to the fuel cell body; Supply gas flow detecting means for detecting a flow rate of the supply gas flowing through the gas supply passage; pure water injection means for supplying pure water to the supply gas flowing through the gas supply passage; and the pure water injection means A pure water temperature detecting means for detecting a temperature of the pure water supplied to the fuel cell; a battery load detecting means for detecting a battery load of the fuel cell main body; and a temperature detecting means for detecting a temperature in the fuel cell main body. Battery internal temperature detecting means, based on signals from the supply gas flow rate detecting means, the pure water temperature detecting means, the battery load detecting means and the battery internal temperature detecting means, A fuel cell, comprising: control means for controlling. 2. The fuel cell according to claim 1, further comprising a supply gas temperature detecting means for detecting a temperature of the supply gas flowing through the gas supply passage, wherein the control means comprises a control unit for detecting a temperature of the supply gas from the supply gas temperature detecting means. Wherein the pure water injection means is controlled by adding the signal of Detecting a flow rate of a supply gas sent through a gas supply passage to a fuel cell body incorporating a fuel cell structure in which an anode electrode and a cathode electrode are opposed to each other with an electrolyte membrane interposed therebetween; A step of detecting a temperature of pure water injected into the supply gas flowing through the gas supply passage; a step of detecting a cell load of the fuel cell main body; a step of detecting a temperature inside the fuel cell main body; Controlling the pure water injection means based on the detected flow rate of the supplied gas, the temperature of the pure water, the battery load, and the battery internal temperature. 4. The control method according to claim 3, further comprising: reading a gas flow rate correction value based on the detected flow rate of the supply gas, and reading a basic pure water injection amount corresponding to the gas flow rate correction value. Reading a pure water temperature correction value, a battery load correction value and a battery internal temperature correction value based on the detected temperature of the pure water, the battery load and the battery internal temperature; and Based on the pure water temperature correction value, the battery load correction value and the battery internal temperature correction value,
Calculating a pure water injection amount to be injected into the supply gas. 5. The control method according to claim 4, wherein a temperature of the supply gas flowing through the gas supply passage is detected, and a gas temperature correction value is read based on the detected temperature of the supply gas. A fuel cell control method comprising calculating the pure water injection amount by adding a gas temperature correction value.