JP2004179080A - Fuel supply device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove an impure gas which stays in a hydrogen electrode space while a system is left standing, before the power generation of a fuel cell system is started. <P>SOLUTION: A hydrogen tank 3 is connected to the hydrogen electrode 2A of the fuel cell 2 via a hydrogen supply passage 4, and a hydrogen shut-off valve 6 is provided in this hydrogen supply passage 4. A hydrogen-circulating passage 4A is provided in the hydrogen supply passage 4, and an unused hydrogen, which does not contribute to the generation of the fuel cell 2, is circulated to the fuel cell 2 and is recycled. A pressure sensor 9 for detecting the pressure of the hydrogen, flowing from the hydrogen tank 3 to the fuel cell 2 at the inlet side of the hydrogen electrode 2A, is provided at the hydrogen-circulating passage 4A. The time, from the valve-opening starting time of the hydrogen shut-off valve 6 to the valve-opening starting time of a hydrogen purge valve 10 is set, in response to the detected value by the pressure sensor 9. When this time has elapsed, the pressure of the inlet side of the hydrogen electrode 2A is considered to have risen to "atmospheric pressure + several kPas", and the hydrogen purge valve 10 is opened. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel supply device for a fuel cell that supplies hydrogen to a fuel cell serving as a power source of an electric vehicle, for example.
[0002]
[Prior art]
When starting a fuel cell system that is a power source of an electric vehicle (hereinafter referred to as a vehicle), hydrogen from a hydrogen tank is supplied to a hydrogen electrode space of the fuel cell, and after the hydrogen pressure reaches a predetermined pressure, Methods for starting power generation are known. That is, the fuel cell system has a configuration in which a hydrogen shutoff valve (hydrogen supply port) is provided on the upstream side of the hydrogen electrode of the fuel cell and a hydrogen purge valve (hydrogen discharge port) is provided on the downstream side. Then, the hydrogen purge valve is closed and the hydrogen shut-off valve is opened. In this state, hydrogen is supplied to the hydrogen electrode space of the fuel cell system, and after the hydrogen pressure reaches a predetermined pressure, power generation is started. It is started to increase power generation efficiency.
[0003]
Further, when such hydrogen is used as a fuel, a circulation system is used for supplying hydrogen to the fuel cell stack constituting the fuel cell system in order to increase its utilization efficiency (improve fuel efficiency) (for example, Patent Document 1). As a circulation system, a blower for pressurizing hydrogen, an ejector for generating negative pressure and sucking hydrogen, a hydrogen pump, and the like are used. As a result, unused hydrogen that has not contributed to power generation in the fuel cell is circulated to the fuel cell, thereby improving fuel efficiency.
[0004]
[Patent Document 1]
JP-A-6-275300 (page 4, FIG. 1)
[0005]
[Problems to be solved by the invention]
By the way, in the prior art, after the fuel cell system is stopped for a long time (for example, when the fuel cell system is stopped overnight), an impurity gas such as air gradually flows to the hydrogen electrode side with the lapse of time after the stop. And the concentration of hydrogen at the hydrogen electrode decreases.
[0006]
In order to solve such a problem, a method is conceivable in which the hydrogen purge valve is opened before the start of power generation to discharge impurities together with hydrogen to the outside. However, depending on the elapsed time after the fuel cell system is stopped and the fluctuation of the atmospheric pressure, the pressure in the hydrogen electrode may be reduced to the atmospheric pressure or less. Impurities may flow back to the pole side, and there is a problem that the reliability of the fuel cell system is reduced. That is, when the power generation of the fuel cell is stopped, hydrogen remains in the gas passage of the fuel cell. However, hydrogen permeates from the hydrogen electrode to the air electrode through the solid polymer membrane due to cross leak, and the hydrogen flows over the air electrode. , The hydrogen gas remaining in the hydrogen electrode is consumed, and the gas pressure at the hydrogen electrode decreases. Since only hydrogen exists at the hydrogen electrode, the power generation consumption may drop below atmospheric pressure in some cases. When the hydrogen purge valve is opened when the fuel cell is restarted in this state, the atmosphere is sucked ( Backflow). That is, the prior art does not consider such a problem.
[0007]
Therefore, according to the present invention, before starting the power generation in the fuel cell system, the impurity gas (air) staying inside (hydrogen electrode space) while the system is left is efficiently removed and replaced with high-concentration hydrogen. Accordingly, it is an object of the present invention to provide a fuel cell fuel supply device capable of smoothly starting (starting power generation) a fuel cell system.
[0008]
[Means for Solving the Problems]
A fuel supply device for a fuel cell according to the present invention that solves the above-mentioned problems includes a hydrogen tank that stores hydrogen to be supplied to the fuel cell, a hydrogen shutoff valve that flows and shuts off between the hydrogen tank and the fuel cell, A hydrogen circulation path for circulating unused hydrogen not contributing to power generation in the battery to the fuel cell; and a hydrogen purge valve located downstream of the hydrogen cutoff valve for purging hydrogen in the hydrogen circulation path. are doing.
[0009]
The first aspect of the present invention is characterized in that, when the hydrogen shutoff valve is opened, a pressure detection unit that detects a pressure of a hydrogen electrode of the fuel cell and a detection value of the pressure detection unit. Valve opening start time setting means for setting the valve opening start time of the hydrogen purge valve accordingly.
[0010]
In such a configuration, the pressure of the hydrogen electrode of the fuel cell can be detected by the pressure detecting means when the hydrogen shut-off valve is opened. Therefore, the valve opening start time of the hydrogen purge valve is set in accordance with the detection value of the pressure detecting means. Can be set. Thus, backflow of the impurity gas such as air into the hydrogen circulation path can be prevented, and the purge of hydrogen in the hydrogen circulation path can be performed smoothly.
[0011]
Further, the feature of the configuration adopted by the invention according to claim 2 is that a pressure detecting means for detecting the pressure of the hydrogen electrode of the fuel cell,
Determining means for determining whether the detection value of the pressure detecting means is equal to or greater than a predetermined value,
A hydrogen purge valve opening means for opening the hydrogen purge valve when the detection value of the pressure detection means becomes equal to or more than a predetermined value after the opening of the hydrogen cutoff valve.
[0012]
In the case of such a configuration, the pressure of the hydrogen electrode of the fuel cell can be detected by the pressure detecting means when the hydrogen shutoff valve is opened, so that the determining means determines whether or not the detected value of the pressure detecting means is equal to or more than a predetermined value. be able to. When the value detected by the pressure detecting means is equal to or more than a predetermined value, the hydrogen purge valve can be opened by the hydrogen purge valve opening means, and the hydrogen in the hydrogen circulation path can be purged smoothly. Therefore, the backflow of the impurity gas such as air into the hydrogen circulation path can be prevented.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
A fuel supply device for a fuel cell according to a first embodiment of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is a configuration diagram showing a configuration of a fuel supply device according to the present embodiment, and FIG. 2 is a flowchart of control by a fuel supply control device. FIG. 3 is a characteristic diagram showing the relationship between the hydrogen electrode inlet pressure and the hydrogen purge valve opening start time, and FIG. 4 is a time chart showing the relationship between the hydrogen electrode inlet pressure, the hydrogen cutoff valve, and the hydrogen purge valve. is there.
[0015]
As shown in FIG. 1, a fuel supply device 1 includes a hydrogen tank 3 for storing hydrogen as a fuel to be supplied to a fuel cell 2, and a hydrogen supply connecting the hydrogen tank 3 and a hydrogen electrode 2 </ b> A of the fuel cell 2. There is provided a passage 4 and an air supply passage 5 for supplying air to the air electrode 2B of the fuel cell 2.
[0016]
Here, a hydrogen shut-off valve 6 is provided on the upstream side of the hydrogen supply passage 4, and the hydrogen shut-off valve 6 is normally kept in a closed state, and is provided between the hydrogen electrode 2 A of the fuel cell 2 and the hydrogen tank 3. Is shut off. Then, when a signal from the ECU 13 described later is input to the hydrogen shutoff valve 6, the hydrogen shutoff valve 6 opens and allows the fuel to flow between the fuel cell 2 and the hydrogen tank 3 via a regulator (not shown). .
[0017]
The hydrogen supply path 4 has a hydrogen circulation path 4A. The hydrogen circulation path 4A circulates unused hydrogen that has not contributed to the power generation in the fuel cell 2 to the fuel cell 2 for reuse. is there. A hydrogen pump 7 pressurizes the hydrogen in the hydrogen circulation path 4A in the direction of the arrow in FIG. 1 and a negative pressure is generated in the hydrogen supply path 4 to supply hydrogen from the hydrogen tank 3 to the hydrogen circulation path 4A. An ejector 8 for suctioning and a pressure sensor 9 serving as pressure detecting means for detecting the pressure of hydrogen flowing into the fuel cell 2 from the hydrogen tank 3 on the inlet side of the hydrogen electrode 2A are provided. Note that a configuration in which one of the hydrogen pump 7 and the ejector 8 is omitted may be adopted. Although the hydrogen pump 7 and the ejector 8 are provided in series in the hydrogen circulation path 4A, they may be provided in parallel.
[0018]
Further, the hydrogen supply path 4 is provided with a hydrogen purge valve 10 located downstream of the hydrogen cutoff valve 6 for purging hydrogen in the hydrogen circulation path 4A. The hydrogen purge valve 10 is normally closed and opens when a signal from the ECU 13 is input to purge hydrogen in the hydrogen circulation path 4.
[0019]
On the other hand, the air supply path 5 is provided with a supercharger 11 for blowing air toward the air electrode 2B of the fuel cell 2 and a pressure adjusting valve 12 for adjusting the pressure of air or the like flowing in the air supply path 5. ing. The pressure regulating valve 12 is normally closed, and opens when a signal from the ECU 13 is input.
[0020]
Next, control of an ECU (Electrical Control Unit) 13 serving as a fuel supply control device that controls the fuel supply device 1 will be described with reference to FIGS.
[0021]
First, in step 1 of FIG. 2, it is determined whether or not the ignition switch 14 (see FIG. 1) is ON. If it is ON (Yes), the process proceeds to step 2, and if it is OFF (No), Returning to step 1, the process is repeated.
[0022]
Next, in step 2, the hydrogen shutoff valve 6 is opened and the hydrogen pump 7 is operated to supply hydrogen from the hydrogen tank 3 to the hydrogen electrode 2A of the fuel cell 2 via the hydrogen supply path 4. Further, the supercharger 11 is operated, the pressure regulating valve 12 is opened, and air is supplied to the air electrode 2B of the fuel cell 2 via the air supply path 5, and the process proceeds to step 3.
[0023]
In step 3, the pressure sensor 9 detects the hydrogen pressure P1 on the inlet side of the hydrogen electrode 2A. That is, the pressure sensor 9 turns on the ignition switch 14 and detects the pressure before the reaction gas is supplied into the hydrogen electrode 2A of the fuel cell 2, that is, the pressure of the hydrogen electrode 2A when power generation is stopped. Here, the ECU 13 has a characteristic diagram shown in FIG. 3, and calculates a predetermined time (valve opening start time) T1 corresponding to the hydrogen pressure P1 based on the characteristic diagram. In this characteristic diagram, in order to prevent the backflow of the impure gas into the hydrogen circulation path 4A as described later, the opening time of the hydrogen shutoff valve 6 is set to be longer as the hydrogen pressure P1 is smaller. I have. Then, the ECU 13 sets a time T1 (see FIG. 4) from the opening start time of the hydrogen shutoff valve 6 to the opening start time of the hydrogen purge valve 10 according to the value detected by the pressure sensor 9 (pressure P1). It has a valve opening start time setting means.
[0024]
Next, in step 4, it is determined whether or not a predetermined time T1 has elapsed since the opening of the hydrogen shutoff valve 6. When the predetermined time T1 has elapsed (Yes), it is considered that the hydrogen pressure P1 has increased to "atmospheric pressure + several kPa" (see FIG. 4), and the routine proceeds to step 5. When the predetermined time T1 has not elapsed (No), it is considered that the hydrogen pressure P1 has not reached “atmospheric pressure + several kPa”, and the process of step 4 is repeated.
[0025]
Finally, in step 5, the hydrogen purge valve 10 is kept open for a predetermined time T2 (see FIG. 4) using a timer (not shown) or the like, and during this time, the hydrogen circulation path 4A The hydrogen inside is purged, and the process ends.
[0026]
As described above, in the present embodiment, as shown in FIG. 4, before the power generation by the fuel cell 2 is started, the hydrogen purge is performed with the hydrogen electrode inlet pressure (P1) previously set to “atmospheric pressure + several kPa”. The hydrogen purge in the hydrogen circulation path 4A can be performed by the valve 10, the backflow of the impurity gas such as air into the hydrogen circulation path 4A can be prevented, and the hydrogen in the hydrogen circulation path 4A can be smoothly purged. Can be.
[0027]
Therefore, before the start of power generation, the impurity gas (air) staying in the hydrogen electrode 2A space of the fuel cell 2 can be efficiently removed, whereby the inside of the hydrogen circulation path 4A can be replaced with high-concentration hydrogen. Thus, the start-up (start of power generation) of the fuel cell 2 can be performed smoothly. Note that “several kPa” in “atmospheric pressure + several kPa” is determined from the viewpoint of preventing the backflow of the impurity gas.
[0028]
(Second embodiment)
Next, FIG. 5 is a flowchart of control by the fuel supply control device according to the second embodiment of the present invention. Thus, control of the ECU serving as the fuel supply control device according to the present embodiment will be described with reference to FIG.
[0029]
First, in step 11, it is determined whether or not the ignition switch 14 is ON. If it is ON (Yes), the process proceeds to step 12, and if it is OFF (No), the process returns to step 11 and the process is repeated. .
[0030]
Next, in step 12, the hydrogen shutoff valve 6 is opened and the hydrogen pump 7 is operated to supply hydrogen from the hydrogen tank 3 to the hydrogen electrode 2A of the fuel cell 2 via the hydrogen supply path 4. Further, the supercharger 11 is operated, the pressure regulating valve 12 is opened, and air is supplied to the air electrode 2B of the fuel cell 2 via the air supply path 5, and the process proceeds to step S13.
[0031]
In step 13, the pressure sensor 9 detects the hydrogen pressure P1 on the inlet side of the hydrogen electrode 2A, and determines whether or not the hydrogen pressure P1 is greater than a predetermined value (atmospheric pressure + several kPa). I do. As with the first embodiment, the ignition switch 14 is turned on for the pressure sensor 9 so that the pressure before the reaction gas is supplied to the hydrogen electrode 2A of the fuel cell 2, that is, the hydrogen when the power generation is stopped, The pressure of the pole 2A is detected. The ECU 13 according to the present embodiment has a determination unit that determines whether the detection value of the pressure sensor 9 is equal to or greater than a predetermined value.
[0032]
If the hydrogen pressure P1 is higher than the predetermined value (atmospheric pressure + several kPa) in step 13 (Yes), the process proceeds to step 14, and if lower (No), the process returns to step 13 and repeats the process.
[0033]
In step 14, the hydrogen purge valve 10 is kept open for a certain period of time. During this time, the hydrogen in the hydrogen circulation path 4A is purged, and the process ends. That is, the ECU 13 according to the present embodiment has a hydrogen purge valve opening unit that holds the hydrogen purge valve 10 in the open state when the hydrogen pressure P1 detected by the pressure sensor 9 is equal to or higher than a predetermined value.
[0034]
Also in the present embodiment configured as described above, before the power generation by the fuel cell 2 starts, the hydrogen circulation by the hydrogen purge valve 10 is performed in a state where the hydrogen electrode inlet pressure (P1) is previously set to “atmospheric pressure + several kPa”. The hydrogen purging in the passage 4A can be performed, the backflow of the impurity gas such as air into the hydrogen circulation passage 4A can be prevented, and substantially the same operation and effect as in the first embodiment can be obtained.
[0035]
Lastly, the present invention is not limited to the fuel supply device according to each of the above-described embodiments, and can be implemented with appropriate modifications without departing from the technical scope of the invention. For example, in each embodiment, hydrogen was supplied to the fuel cell as fuel, but any fuel may be used as long as it reacts with oxygen in compressed air. For example, an organic hydrogen-containing compound may be reformed in a reformer. By doing so, reformed hydrogen and the like generated can also be supplied.
[0036]
【The invention's effect】
As described in detail above, according to the first aspect of the present invention, before the power generation of the fuel cell is started, the pressure detecting means opens the hydrogen purge valve according to the pressure of the hydrogen electrode at the time of opening the hydrogen shutoff valve. Since the valve start time is set, it is possible to prevent the backflow of the impurity gas such as air into the hydrogen circulation path, and to smoothly purge the hydrogen within the hydrogen circulation path. Therefore, before the start of power generation by the fuel cell, the impurity gas remaining in the hydrogen electrode space of the fuel cell can be efficiently removed, and the inside of the hydrogen circulation path can be replaced with high-concentration hydrogen. Startup (power generation start) can be performed smoothly.
[0037]
According to the second aspect of the invention, when the detected value of the pressure detecting means is equal to or more than the predetermined value, the hydrogen purge valve is opened by the hydrogen purge valve opening means. Can be smoothly performed, and in the same manner as in the first aspect of the present invention, backflow of impurity gas such as air into the hydrogen circulation path can be prevented before the start of power generation by the fuel cell. Impurity gas remaining in the hydrogen electrode space of the battery can be efficiently removed. Then, the inside of the hydrogen circulation path can be replaced with high-concentration hydrogen, and the fuel cell can be smoothly started (start of power generation).
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a fuel supply device for a fuel cell according to a first embodiment of the present invention.
FIG. 2 is a flowchart of control by an ECU in FIG. 1;
FIG. 3 is a characteristic diagram showing a relationship between a hydrogen electrode inlet pressure and a hydrogen purge valve opening start time according to the first embodiment.
FIG. 4 is a time chart showing a relationship between a hydrogen electrode inlet pressure, a hydrogen cutoff valve, and a hydrogen purge valve according to the first embodiment.
FIG. 5 is a flowchart of control of an ECU according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel supply device 2 Fuel cell 2A Hydrogen electrode 2B Air electrode 3 Hydrogen tank 4 Hydrogen supply path 6 Hydrogen shutoff valve 9 Pressure sensor (pressure detecting means)
10 hydrogen purge valve 13 ECU (fuel supply control device)

Claims (2)

A hydrogen tank that stores hydrogen to be supplied to the fuel cell, a hydrogen shutoff valve that circulates and shuts off the hydrogen tank and the fuel cell, and supplies unused hydrogen that has not contributed to power generation in the fuel cell to the fuel cell. In a fuel supply device for a fuel cell, comprising: a hydrogen circulation path to be circulated; and a hydrogen purge valve positioned downstream of the hydrogen cutoff valve to purge hydrogen in the hydrogen circulation path.
At the time of opening the hydrogen cutoff valve, pressure detecting means for detecting the pressure of the hydrogen electrode of the fuel cell,
A fuel supply device for a fuel cell, comprising: valve opening start time setting means for setting a valve opening start time of a hydrogen purge valve according to a value detected by the pressure detecting means. A hydrogen tank that stores hydrogen to be supplied to the fuel cell, a hydrogen shutoff valve that circulates and shuts off the hydrogen tank and the fuel cell, and unused hydrogen that has not contributed to power generation in the fuel cell. In a fuel supply device for a fuel cell, comprising: a hydrogen circulation path to be circulated; and a hydrogen purge valve located downstream of the hydrogen cutoff valve to purge hydrogen in the hydrogen circulation path.
Pressure detection means for detecting the pressure of the hydrogen electrode of the fuel cell,
Determining means for determining whether the detected value of the pressure detecting means is equal to or greater than a predetermined value,
A hydrogen purge valve opening means for opening the hydrogen purge valve when a detection value of the pressure detection means becomes equal to or more than a predetermined value after the opening of the hydrogen cutoff valve. Battery fuel supply.

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