JP2001229945A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize unreacted hydrogen in a fuel cell system. SOLUTION: A second FC stack 210 is provided for generating power which uses noreaction hydrogen in a first FC stack 200 as a fuel. When the increasing change rate of a stepping operation amount Δof an acceleration pedal is positive, namely the operation amount Δ tends to increase, a hydrogen valve 505 provided in a hydrogen passage via which the unreacted hydrogen in the first FC stack 200 is fed to the second FC stack 210 is closed. When the increasing change rate of the stepping operation amount Δ is however zero or lower, namely the operation amount Δ tends to decrease or is constant, the hydrogen valve 505 is opened. Power generated by the second FC stack 210 is supplied to accessories (m) and a battery V. As a result, the unreacted hydrogen is used effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system applied to a system that operates using electric energy generated by a chemical reaction between hydrogen and oxygen as a power source, such as a vehicle, a ship, and a portable generator. It is effective when applied to moving objects.

[0002]

2. Description of the Related Art As described above, a fuel cell generates electric power by chemically reacting hydrogen and oxygen.
It is necessary to supply hydrogen and oxygen according to the required electric energy. For this reason, if more than necessary hydrogen is supplied to the fuel cell, unreacted hydrogen is released together with exhaust gas (such as water vapor and carbon dioxide).

On the other hand, for example, Japanese Patent Application Laid-Open No. 11-797 / 1999
According to the invention described in Japanese Patent Publication No. 2 (1994), unreacted hydrogen is recovered, and the recovered unreacted hydrogen is reused as heating fuel for the reformer.

[0004]

By the way, the case where unreacted hydrogen is generated in the first place is a case where the amount of supplied hydrogen is larger than the required amount of electric power (power generation amount). When the recovered unreacted hydrogen is reused as heating fuel for the reformer, the amount of hydrogen generated in the reformer (hydrogen production unit) increases. Reuse as fuel is not always an appropriate measure.

[0005] In view of the above, it is an object of the present invention to appropriately treat unreacted hydrogen discharged from a fuel cell.

[0006]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, a first fuel cell (200) for generating electric energy by reacting hydrogen and oxygen. And an operating force generating means (M) that operates by obtaining electric energy from the first fuel cell (200), and generates electric energy by a chemical reaction between unreacted hydrogen and oxygen discharged from the first fuel cell (200). And a second fuel cell (210) to be generated.

[0007] This makes it possible to generate electric power with unreacted hydrogen and use the generated electric power effectively.

According to the second aspect of the present invention, there is provided a hydrogen generator (100) for reforming a hydrocarbon-based fuel to produce a hydrogen-rich gas containing a large amount of hydrogen, and a first fuel cell (20).
0) from the second fuel cell (21).
0) is provided with a valve (505) for opening and closing the exhaust passage leading to the first fuel cell (20) from the hydrogen generator (100).
The valve (505) is opened when the rate of change in the amount of the hydrogen-rich gas supplied to (0) falls below a predetermined value.

Thus, it is possible to prevent the amount of hydrogen in the first fuel cell (200) from being lower than the amount of hydrogen originally required by the first fuel cell (200), that is, the operating force generating means (M). In addition, unreacted hydrogen can be used effectively.

[0010] As described in the third aspect of the invention, if the secondary battery (V) can be supplied with power from the second fuel cell (210), unreacted hydrogen can be further reduced. It can be used more effectively.

Further, according to the invention described in claim 4,
If the electric device (m) can be supplied with electric power from the second fuel cell (210), the unreacted hydrogen can be more effectively used.

Incidentally, the reference numerals in parentheses of the above-mentioned means are examples showing the correspondence with specific means described in the embodiments described later.

[0013]

(Embodiment) In this embodiment, a fuel cell system according to the present invention is applied to an electric vehicle (hereinafter abbreviated as "vehicle"), and FIG. 1 shows a first embodiment. It is a schematic diagram which shows a fuel cell system.

A reference numeral 100 (enclosed by a dashed line) produces (generates) a hydrogen-rich gas containing a large amount of hydrogen from a mixed solution of water and methanol (hereinafter, this mixed solution is referred to as a methanol mixed solution). A hydrogen producing device (hydrogen supplying means) for supplying a hydrogen-rich gas to a first fuel cell 200 described later. The hydrogen producing device 100 is a hydrogen producing fuel evaporator (hereinafter, evaporating) for evaporating a methanol mixed solution. 110) and a chemical reaction between the methanol vapor evaporated (vaporized) in the evaporator 110 and water vapor,
The fuel cell system is provided with a fuel reformer (hereinafter, abbreviated as reformer) 120 for hydrogen production that reforms into hydrogen, carbon dioxide, and a small amount of carbon monoxide.

Reference numeral 130 denotes a methanol mixed solution tank mounted on the vehicle to store the methanol mixed solution, and 131 denotes a first pump for sending the methanol mixed solution in the methanol mixed solution tank 130 toward the evaporator 110. .

Reference numeral 200 denotes a first fuel cell (hereinafter, referred to as a first fuel cell) for generating a voltage of 288 volts by generating a chemical reaction between the hydrogen-rich gas produced by the hydrogen producing apparatus 100 and air (oxygen).
Notated as FC stack. ), The driving electric motor (operating force generating means) M is driven by the electric power generated by the first FC stack 200.

Since the catalytic function of the electrode catalyst in the first FC stack 200 is easily reduced by carbon monoxide, in this embodiment, the carbon monoxide generated in the reformer 120 is oxidized to carbon dioxide. Changing carbon monoxide reducer 1
40 is provided in the hydrogen generator 100.

A second fuel cell 210 (hereinafter referred to as a second FC cell) for generating a voltage of 12 volts generates electric power by chemically reacting unreacted hydrogen and oxygen discharged from the first FC stack 200.
Notated as stack. ), And auxiliary equipment (electric equipment) different from the traveling electric motor M such as a compressor or a fuel pump due to the electric power generated by the second FC stack 210.
m and a secondary battery (battery) V that can be charged and discharged.

The accessories m and the battery V are connected to the second F
When power is not supplied from the C stack 210,
Electric power is supplied from a generator such as an alternator driven by the traveling electric motor M.

Reference numeral 221 denotes the first and second FC stacks 200,
An air humidifier that humidifies the air sent to 210,
Reference numeral 222 denotes a dehumidifier that cools exhaust gas (steam, air, etc.) discharged from the first and second FC stacks 200 and 210 to remove and recover moisture. Then, the water separated and removed by the dehumidifier 222 is returned to the air humidifier 221 via the condensed water return passage 223, and is returned to the first and second FC stacks 20.
It is reused for humidifying the air blown to 0 and 210.

The first and second FC stacks 200 and 21
2, the positive electrode side and the negative electrode side are separated with a polymer film interposed therebetween as shown in FIG. 2, air (oxygen) is supplied to the positive electrode side, and hydrogen-rich gas is supplied to the negative electrode side. Therefore, exhaust containing a large amount of water vapor is discharged from the positive electrode side, and unreacted hydrogen gas, carbon dioxide, and the like are discharged from the negative electrode side.

In FIG. 1, reference numeral 300 denotes a methanol fuel tank which is mounted on a vehicle and stores fuel for heating the evaporator 110 (in this embodiment, methanol), and 310 is stored in the methanol fuel tank 300. The second pump sends methanol (fuel) to the evaporator 110. Reference numeral 311 denotes a fuel return valve that opens and closes a methanol return passage 312 that returns a part of the methanol discharged from the second pump 310 to the methanol fuel tank 300.

An air pump 400 sucks air from the outside and blows air to the hydrogen generator 100 (evaporator 110 and reformer 120) and the first and second FC stacks 200 and 210. The combustion exhaust gas generated at 100 and the exhaust generated at the first FC stack 200 flow through the exhaust passages 411 to 414 and are discharged to the atmosphere.

Reference numeral 501 denotes a first air distribution valve which distributes the blast air discharged from the air pump 400 to the hydrogen generator 100 and the first FC stack 200 and adjusts the distribution amount. 50
The air distributed to the hydrogen production device 100 by the first and second air distribution valves 502 and 503 is supplied to the evaporator 1
10, while being distributed to the reformer 120 and the carbon monoxide reducer 140, the distribution amount is adjusted.

Reference numeral 504 denotes a methanol valve for supplying methanol supplied from the methanol fuel tank 300 to the evaporator 110 and the reformer 120 and adjusting the supply amount. Reference numeral 505 denotes an exhaust gas on the negative electrode side of the first FC stack 200. A hydrogen valve for opening and closing the port 505a. Incidentally, in the present embodiment, the exhaust gas from the exhaust port on the negative electrode side of the second FC stack 210 is also discharged to the atmosphere as in the exhaust passage 414.

FIG. 3 is a control block diagram of the fuel cell system according to this embodiment. Reference numeral 601 denotes an accelerator sensor (accelerator operation) for detecting the amount of depression of an accelerator pedal (not shown) operated by the driver. The detection signal of the accelerator sensor 601 is input to an FC system controller (hereinafter, referred to as FCCU) 600 for controlling the entire fuel cell system.

The accelerator pedal controls the output of the electric motor M for traveling by the driver's operation. In this embodiment, the output of the electric motor M for traveling is increased as the operation amount of the accelerator pedal is increased. As the amount increases, the amount of hydrogen-rich gas supplied to the first FC stack 200 increases. On the other hand, as the operation amount of the accelerator pedal decreases, the output of the traveling electric motor M decreases, and the amount of the hydrogen-rich gas supplied to the first FC stack 200 decreases. The fuel cell system is controlled so that the amount of the hydrogen-rich gas decreases.

Similarly, the first to third air distribution valves 501 to 501
The FCCU 503 and the methanol valve 504 detect the FCCU 6 based on the detection signal of the sensor group S that detects the operation state such as the temperature of the first FC stack 200 and the load of the traveling electric motor.
00.

Next, the operation of the hydrogen valve 505 which is a feature of this embodiment will be described.

FIG. 4 shows the operation amount Δ of the accelerator pedal.
(Hereinafter, abbreviated as an operation amount Δ).
The operation amount Δ changes with the running state (time) of the vehicle. At this time, when the rate of increase in the operation amount Δ is positive (when the amount of operation Δ is on the rise), the rate of increase in the amount of hydrogen-rich gas supplied to the first FC stack 200 is positive (greater than zero). , The hydrogen valve 505 is closed.

As a result, the first F
The hydrogen-rich gas supplied to the C stack 200 is
The power is consumed by the first FC stack 200 without flowing out to the FC stack 210, and the power generation amount increases.

On the other hand, when the increasing change rate of the manipulated variable Δ is equal to or less than zero (when the manipulated variable Δ is falling or in a constant tone),
Assuming that the rate of increase in the amount of hydrogen-rich gas supplied to the first FC stack 200 is less than or equal to zero, the hydrogen valve 505
open.

As a result, the first F
Since unreacted hydrogen among the hydrogen-rich gas supplied to the C stack 200 is supplied to the second FC stack 210, power generation is started in the second FC stack 210, and power is supplied to the accessories m and the battery V. .

Next, the features of this embodiment will be described.

The unreacted hydrogen and oxygen discharged from the first FC stack 200 are chemically reacted to generate power,
Since it has the second FC stack 210 different from the first FC stack 200 that supplies electric power to the traveling electric motor M, it is possible to generate electric power with unreacted hydrogen and use the generated electric power effectively.

At this time, as in the present embodiment, the second FC
If the electric power generated by the stack 210 is supplied to the accessories m and the battery V, the load on the electric motor M for traveling can be reduced, and the unreacted hydrogen can be used more effectively.

In this embodiment, when the rate of change of the manipulated variable Δ becomes zero or less, the hydrogen valve 505 is opened to supply unreacted hydrogen to the second FC stack 210. Or surplus hydrogen (unreacted hydrogen), such as when changing from acceleration to running at a constant speed
Unreacted water can be surely supplied to the second FC stack 210 only when the occurrence of water is likely to occur. Therefore, it is possible to effectively use unreacted hydrogen while preventing the amount of hydrogen in the first FC stack 200 from being lower than the amount of hydrogen originally required in the first FC stack 200 (the electric motor M for traveling). it can.

(Other Embodiments) In the above embodiment, the hydrogen valve 50 is operated based on the operation amount of the accelerator pedal.
Although the hydrogen valve 505 is opened and closed, the hydrogen valve 505 may be opened and closed based on other parameters indicating the traveling state such as the electric power required by the traveling electric motor M.

In the above embodiment, the hydrogen valve 5
Although the opening / closing control of the hydrogen valve 505 is simply performed, the opening of the hydrogen valve 505 may be continuously adjusted based on other parameters indicating the running state such as the operation amount of the accelerator pedal.

Further, in the above-described embodiment, the second FC stack 210 is for 12 V, but this is in accordance with the operating voltage of the accessories m and the battery V, and the present invention is not limited to this. Not something.

In the above-described embodiment, the hydrogen supply device 100 is used as the hydrogen supply means for reforming the hydrocarbon fuel to produce a hydrogen-rich gas containing a large amount of hydrogen. However, the present invention is not limited to this, and a high-pressure hydrogen tank that can supply pure hydrogen gas, a hydrogen tank using a hydrogen storage alloy, or the like may be used as the hydrogen supply means.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram of an FC stack.

FIG. 3 is a control block diagram of the fuel cell system according to the first embodiment of the present invention.

FIG. 4 is a graph showing a change in an accelerator pedal operation amount Δ.

[Explanation of symbols]

100: hydrogen generator, 200: first FC stack (first
Fuel cell), 210: second FC stack (second fuel cell), 505: hydrogen valve.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kunio Okamoto 1-1-1, Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (Reference) 5H027 AA02 AA06 BA01 BA16 DD03 KK00 MM08

Claims (4)

[Claims] 1. A fuel cell system applied to a system that operates using electric energy generated by a chemical reaction between hydrogen and oxygen as a power source, wherein a first reaction is performed by reacting hydrogen and oxygen to generate electric energy. A fuel cell (200); an operating force generating means (M) that operates by receiving electric energy from the first fuel cell (200); and unreacted hydrogen and oxygen discharged from the first fuel cell (200). And a second fuel cell (210) for generating electric energy by the chemical reaction of (2). 2. A hydrogen generator (10) for reforming a hydrocarbon fuel to produce a hydrogen-rich gas containing a large amount of hydrogen.
0), and a valve (505) for opening and closing an exhaust passage for guiding unreacted hydrogen discharged from the first fuel cell (200) to the second fuel cell (210). ) To the first fuel cell (20
2. The fuel cell system according to claim 1, wherein the valve is opened when a rate of change in the amount of hydrogen-rich gas supplied to 0) becomes equal to or less than a predetermined value. 3. 3. A chargeable / dischargeable secondary battery (V), wherein the secondary battery (V) is configured to be able to receive power supply from the second fuel cell (210). The fuel cell system according to claim 1, wherein: 4. An electric device (m) different from the operating force generating means (M), wherein the electric device (m) can receive power supply from the second fuel cell (210). The fuel cell system according to any one of claims 1 to 3, wherein the fuel cell system is configured as described above.