JP2001155753A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system which heats the fuel cell and increases the temperature of fuel cell rapidly. SOLUTION: When the temperature of the coolant heated by burning type heater 4 is less than a determined temperature, the temperature of the burning exhaust is decreased by inputting new air into the burning exhaust, the temperature decreased burning exhaust is supplied to the fuel cell 1 and the fuel cell 1 is heated and its temperature is increased, and when the temperature of the coolant is less than the predetermed temperature, the fuel cell 1 is heated and its temperature is increased by burning exhaust cooled and heated coolant. Using that, since the thermal defect of the fuel cell 1 is prevented and heat of burning exhaust is given to the fuel cell 1 with good efficiently, the fuel cell 1 can be rapidly heated and increased in its temperature.

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 for managing the temperature of a fuel cell (heating and raising the temperature), and is effective when applied to a fuel cell vehicle running using a fuel cell as a power source.

[0002]

2. Description of the Related Art As is well known, a fuel cell generates (generates) electric power by utilizing a chemical reaction between hydrogen and oxygen, and is considered as a driving source of a moving body such as a vehicle. In a polymer electrolyte fuel cell, under the temperature condition of 0 ° C. or lower, there is a problem that moisture existing near the electrode freezes, which inhibits the diffusion of the reaction gas and lowers the electric conductivity of the electrolyte membrane. is there.

Therefore, in the invention described in Japanese Patent Application Laid-Open No. 7-94202, for example, a fluid is heated by a combustion-type heater and the heated fluid (hot water) is supplied to the fuel cell to heat the fuel cell. It is warm (warm up).

[0004]

However, immediately after the start of the combustion type heater, the temperature of the combustion type heater and the fluid are reduced to the outside air temperature, and the combustion type heater and the fluid are relatively large. Because it has heat capacity,
A high-temperature fluid (hot water) cannot be supplied to the fuel cell simultaneously with the activation of the combustion heater. Therefore, the fuel cell cannot be heated and heated quickly.

[0005] In view of the above, it is an object of the present invention to quickly heat and raise the temperature of a fuel cell.

[0006]

According to the first aspect of the present invention, there is provided a fuel cell for generating electric power by chemically reacting hydrogen and oxygen.
And a combustion heater (4) for burning fuel to generate heat, and after cooling combustion exhaust gas of the combustion heater (4),
A first fuel cell heating means (8, 8) for guiding the cooled combustion exhaust gas to the fuel cell (1) and heating and raising the temperature of the fuel cell (1).
17) and second fuel cell heating means (5, 14) for circulating the fluid heated by the combustion heater (4) in the fuel cell (1) to heat and raise the temperature of the fuel cell (1). It is characterized by having.

As a result, even immediately after the start of the combustion type heater (4) and the temperature of the fluid is low, the fuel cell (1) can be quickly heated and heated by the high temperature combustion exhaust gas. .

By the way, the temperature of the combustion exhaust is generally 1
Since the temperature is 000 ° C. or higher and higher than the heat-resistant temperature of the fuel cell (1), if the combustion exhaust gas is directly supplied into the fuel cell (1), the fuel cell (1) is damaged.

On the other hand, in the present invention, since the cooled combustion exhaust gas is supplied to the fuel cell (1) after cooling the combustion exhaust gas, it is possible to prevent the fuel cell (1) from being damaged. Can be prevented.

Further, the fuel cell (1) can be heated and heated by both the combustion exhaust gas and the fluid heated by the combustion type heater (4), so that the fuel cell (1) can be heated only by either the combustion exhaust gas or the fluid. The heat generated by the combustion type heater (4) can be effectively given to the fuel cell (1), as compared with the case where the temperature is raised by heating (1).

By the way, when the combustion exhaust gas and the fluid are supplied to the fuel cell (1) when the temperature of the fluid is low, the heat of the combustion exhaust gas is transferred to the low-temperature fluid in the fuel cell (1), so that the combustion is performed. There is a possibility that the heat of the exhaust gas cannot be efficiently supplied to the fuel cell (1).

On the other hand, according to the second aspect of the invention, when the temperature of the fluid heated by the combustion heater (4) is lower than a predetermined temperature, the first fuel cell heating means (8, 1
7) The fuel cell (1) is heated and heated, and when the temperature of the fluid heated by the combustion heater (4) is equal to or higher than a predetermined temperature, it is added to the first fuel cell heating means (8, 17). And the second
It is characterized in that the fuel cell (1) is heated and heated by the fuel cell heating means (5, 14).

Thus, when the temperature of the fluid is low, the heat of the combustion exhaust can be prevented from being transferred to the low-temperature fluid, so that the heat of the combustion exhaust can be efficiently provided to the fuel cell (1). .

[0014] According to a third aspect of the present invention, the combustion exhaust may be cooled by injecting fresh air into the combustion exhaust.

Further, the combustion exhaust gas may be cooled by injecting water into the combustion exhaust gas.

Further, as in the fifth aspect of the present invention, the electric heater (4a) for heating the fluid circulated through the fuel cell (1) may be built in the combustion type heater (4).

Further, as in the sixth aspect of the present invention, it is desirable that the combustion heater (4) generates heat by burning the fuel of the fuel cell (1).

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

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
The fuel cell system according to the present invention is applied to an electric vehicle (fuel cell vehicle) that runs using a fuel cell as a power source, and FIG. 1 is a schematic diagram of the fuel cell system according to the present embodiment.

In FIG. 1, reference numeral 1 denotes a fuel cell (FC stack) that generates electric power by utilizing a chemical reaction between hydrogen and oxygen and supplies electric power to an electric device EV such as a running electric motor or a battery. As shown in FIG. 2, this fuel cell 1 is a known solid polymer composed of an electrolyte membrane 1a, a carbon cloth 1b, a cooling plate 1c, a separator 1d, a refrigerant (fluid) passage 1e, and an air (oxygen) passage 1f. It is also a type.

The hydrogen supplied to the fuel cell 1 is generated from water and methanol, and the generated hydrogen flows through the fuel cell 1 in a direction orthogonal to the air passage 1f. Air (oxygen) flowing in the air passage 1f
To generate electric power. Incidentally, reference numeral 2 denotes a hydrogen pipe for supplying the generated hydrogen to the fuel cell 1, and reference numeral 3 denotes an air pipe through which air supplied to the air passage 1f (the fuel cell 1) flows.

In FIG. 1, reference numeral 4 denotes a combustion heater for burning fuel to generate heat, and reference numeral 5 denotes a refrigerant (fluid) heated by the combustion heater 3 in a fuel cell 1 (refrigerant passage 1).
This is a refrigerant pipe to be supplied (circulated) to f). Reference numeral 6 denotes a radiator that exchanges heat between the refrigerant and the outside air (atmosphere) and cools the refrigerant. The radiator 6 is disposed in the refrigerant circuit so as to be in parallel with the flow of the refrigerant flowing through the combustion type heater 4. ing. In this embodiment, methanol (fuel of the fuel cell 1) is used as fuel for the combustion heater 4 in order to generate hydrogen.

Reference numeral 7 denotes a bypass circuit for circulating the refrigerant flowing out of the combustion type heater 4 and returning to the combustion type heater 4 by bypassing the fuel cell 1. Reference numeral 8 designates the combustion exhaust gas of the combustion type heater 4 as the fuel cell 1 (air passage 1f). ) Exhaust pipe (exhaust passage)
It is.

Reference numeral 9 denotes a bypass circuit 7 and a fuel cell 1
A first flow control valve (first flow control means) for controlling the amount of refrigerant flowing through the second flow control valve (second flow control) for controlling the amount of refrigerant flowing through the radiator 6 and the combustion type heater 4 Means 11 for switching between a case where the combustion exhaust gas is supplied to the fuel cell 1 and a case where the combustion exhaust gas is discharged into the atmosphere, and a third flow control valve (third control valve) for adjusting the amount of the combustion exhaust gas supplied to the fuel cell 1. Flow control means).

Reference numerals 12 and 13 denote a fuel cell 1 (air passage 1f).
A switching valve for switching between a case where air for power generation (air supplied from the air pipe 3) and a case where combustion exhaust gas is circulated therein. The two switching valves 12 and 13 operate in conjunction with each other. Things. Incidentally, in the fuel cell 1 (air passage 1f), the direction of the flow of the air for power generation is opposite to the direction of the flow of the combustion exhaust gas.

Reference numeral 14 denotes a water pump for circulating a refrigerant, 15 denotes a fuel pump for supplying fuel to the combustion type heater 4, and 16 denotes a first air pump for supplying combustion air to the combustion type heater 4. Reference numeral 17 denotes a second air pump which supplies outside air (fresh air) into the exhaust pipe 8 to dilute the combustion exhaust gas to lower its temperature.

Reference numerals 18 and 19 denote first and second sensors for detecting the temperature of the refrigerant.
Two temperature sensors (first and second refrigerant temperature detecting means), the first temperature sensor 18 detects the temperature of the refrigerant immediately after flowing out of the fuel cell 1, and the second temperature sensor 19 flows out of the bypass circuit 7. Detects the temperature of the refrigerant. Reference numeral 20 denotes an FC temperature sensor that detects the temperature of the fuel cell 1 (the electrolyte membrane 1a). The FC temperature sensor 20 detects the temperature of the fuel cell 1 at a plurality of locations.

The detected temperatures of the sensors 18 to 20 are input to an electronic control unit (ECU) 21 as shown in FIG. 3, and the ECU 21 sets in advance based on the detected temperatures of the sensors 18 to 20. According to the program
Devices such as the combustion heater 4, the first to third flow control valves 9 to 11, the switching valves 12 and 13, the water pump 14, the fuel pump 15, and the first and second air pumps 16 and 17 are controlled.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG.

When a vehicle start switch (not shown) is turned on, the temperature of the fuel cell 1 (the temperature detected by the FC temperature sensor 20) is read (S100), and the temperature of the fuel cell 1 (FC temperature) Tfc is determined. It is determined whether the temperature is equal to or higher than the first predetermined temperature T1 and equal to or lower than the second predetermined temperature (S110).

Here, the first predetermined temperature T1 is determined by the fuel cell 1
Means the temperature in which a predetermined margin is added to the lowest temperature at which power can be generated, and the second predetermined temperature takes into account a predetermined margin with respect to the maximum temperature at which power can be generated by the fuel cell. It means temperature.

When the FC temperature Tfc is lower than the first predetermined temperature, the combustion is continued until the temperature Tw1 of the refrigerant flowing out of the bypass circuit 7 (the temperature detected by the second temperature sensor 19) becomes equal to or higher than the third predetermined temperature T3. A third flow control valve 11 and a switching valve 12 so that the exhaust gas flows through the fuel cell 1;
13 so that all of the refrigerant heated by the combustion type heater 4 flows through the bypass circuit 7.
A state in which the flow control valve 9 is operated (hereinafter, this state is referred to as a first state).
Called warm-up mode. ), The water pump 14 and the combustion type heater 4 are started (S120 to S150). Note that the third predetermined temperature T3 is equal to or higher than the first predetermined temperature T1,
The temperature is lower than the predetermined temperature T2.

Thereafter, when the temperature Tw1 becomes equal to or higher than the third predetermined temperature, the temperature T1 of the refrigerant flowing out of the fuel cell 1 is increased.
Until w2 (the temperature detected by the first temperature sensor 18) becomes equal to or higher than the first predetermined temperature T1, the second warming which supplies all the refrigerant heated by the combustion type heater 4 to the fuel cell 1 in addition to the combustion exhaust gas. The machine mode is executed (S160, S170).

Here, in the first and second warm-up modes, fresh air is sent into the exhaust pipe 8 by the second air pump 17, and the combustion exhaust gas is diluted and cooled to be supplied to the fuel cell 1. After the combustion exhaust gas is cooled by the exhaust pipe 8 and the second air pump 17 and the like, the first fuel cell heating means is configured to guide the cooled combustion exhaust gas to the fuel cell 1 to heat and raise the temperature of the fuel cell 1. I have. Further, a second fuel cell heating means for circulating the refrigerant heated by the combustion type heater 4 in the fuel cell 1 by the refrigerant pipe 5 and the water pump 14 to heat and raise the temperature of the fuel cell 1 is configured. .

Thereafter, when the temperature Tw2 of the refrigerant flowing out of the fuel cell 1 becomes equal to or higher than the first predetermined temperature T1, it is considered that the fuel cell 1 is in a state capable of generating power, and the combustion type heater 4 Is stopped to stop supplying combustion exhaust gas to the fuel cell 1 (S180), and hydrogen and oxygen (air) are supplied to the fuel cell 1 to start power generation (S190).

Next, it is determined whether the temperature Tw2 detected after the start of power generation is equal to or higher than the fourth predetermined temperature T4 (S20).
0), when the temperature Tw2 is equal to or higher than the fourth predetermined temperature T4, the refrigerant is circulated to the radiator 6, and the radiator 6 is controlled so that the temperature Tw2 is equal to or higher than the first predetermined temperature T1 and equal to or lower than the second predetermined temperature T2. An FC cooling mode for controlling the amount of refrigerant to be circulated and the amount of cooling air supplied to the radiator 6 is executed (S210). The fourth predetermined temperature T4
Is a temperature equal to or higher than the third predetermined temperature T3 and lower than the second predetermined temperature T2.

Incidentally, when it is determined in S110 that the temperature (FC temperature) Tfc of the fuel cell 1 is equal to or higher than the first predetermined temperature T1 and equal to or lower than the second predetermined temperature, the fuel cell 1 is heated and heated (warm-up). Assuming that there is no need to perform power generation, power generation is started (S190).

At S110, the temperature of the fuel cell 1 (F
When it is determined that (C temperature) Tfc is higher than the second predetermined temperature, it is assumed that the temperature of the fuel cell 1 is excessively increased (overheated), and the refrigerant is circulated between the radiator 6 and the fuel cell 1. To cool the fuel cell 1 (S
200).

Next, the features of this embodiment will be described.

In this embodiment, since the first fuel cell heating means for heating and raising the temperature of the fuel cell 1 by the combustion exhaust gas of the combustion type heater 4 is provided, the refrigerant is supplied immediately after the combustion type heater 4 is started. Even when the temperature is low, the fuel cell 1 can be quickly heated and heated by the high-temperature combustion exhaust gas.

Incidentally, the temperature of the combustion exhaust gas is generally 1
000 ° C. or higher and higher than the heat-resistant temperature of the fuel cell 1 (electrolyte membrane 1a) (about 100 ° C. in the case of the solid polymer type). 1a) is damaged.

On the other hand, in the present embodiment, the fresh air is supplied to the exhaust pipe 8 by the second air pump 17 to lower the temperature of the combustion exhaust (to about 200 ° C.) and the combustion exhaust is Since the fuel cell 1 is supplied, the fuel cell 1 (electrolyte membrane 1a) can be prevented from being damaged.

By the way, when the combustion exhaust gas and the refrigerant are supplied to the fuel cell 1 when the refrigerant temperature is low, the heat of the combustion exhaust is transferred to the low-temperature refrigerant in the fuel cell 1, and the heat of the combustion exhaust gas is efficiently removed. There is a possibility that the fuel cell 1 cannot be provided well.

On the other hand, in the present embodiment, the temperature of the refrigerant heated by the combustion type heater 4 is equal to the third predetermined temperature T3.
When the temperature is lower than the predetermined temperature, the fuel cell 1 is heated and heated by the combustion exhaust gas. When the temperature of the refrigerant becomes equal to or higher than the third predetermined temperature T3, the fuel cell 1 is heated and heated by the combustion exhaust gas and the heated refrigerant. When the refrigerant temperature is low, it is possible to prevent the heat of the combustion exhaust from being transferred to the low-temperature refrigerant. Therefore, the heat of the combustion exhaust gas can be efficiently provided to the fuel cell 1.

When the temperature of the refrigerant heated by the combustion heater 4 is equal to or higher than the third predetermined temperature T3, the fuel cell 1 is heated and heated by both the combustion exhaust gas and the refrigerant heated by the combustion heater 4. The heat generated by the combustion type heater 4 can be effectively given to the fuel cell 1 as compared with the case where the fuel cell 1 is heated and heated only by one of the combustion exhaust and the refrigerant.

Incidentally, in a polymer electrolyte fuel cell,
Although it is necessary to humidify the electrolyte membrane 1a, in this embodiment, since the combustion exhaust is supplied into the fuel cell 1, the electrolyte membrane 1a can be humidified by the water vapor contained in the combustion exhaust.

(Second Embodiment) In the first embodiment, the first
The combustion exhaust gas supplied to the fuel cell 1 is cooled by injecting fresh air into the exhaust pipe 8 by the air pump 17, but in the present embodiment, as shown in FIG. In addition to providing the tank 22, the water stored in the water storage tank 22 is injected into the exhaust pipe 8 by an injector (injection device) 23 to humidify and cool the combustion exhaust gas.

Thus, the combustion exhaust gas can be cooled while humidifying the electrolyte membrane 1a more reliably.

(Third Embodiment) As shown in FIG. 6, this embodiment is a fuel cell system according to the first embodiment (FIG. 1).
1), the bypass circuit 7 for bypassing the fuel cell 1 to return the refrigerant flowing out of the combustion heater 4 to the combustion heater 4 and the second temperature sensor 19 are eliminated.

This embodiment may be applied to the fuel cell system according to the second embodiment (see FIG. 5).

(Fourth Embodiment) In this embodiment, as shown in FIG. 7, an electric heater 4a for heating a refrigerant (fluid) circulated through the fuel cell 1 is built in the combustion type heater 4. In FIG. 7, 4b is an ignition device, and 4c is a fuel injection nozzle.

Thus, in addition to the combustion heat of the combustion type heater 4 (both the heat of the combustion exhaust and the heat supplied to the refrigerant),
Since the heat of the electric heater 4a can be supplied to the fuel cell 1, the fuel cell 1 can be heated and heated in a short time.

In general, in the combustion type heater 4, if the calorific value is excessively reduced, the fuel cannot be stably burned. Therefore, the lower limit of the calorific value is 30% to 50% of the maximum capacity. % And relatively large. Therefore, the fuel cell 1
At a low heat load where the amount of heat required for heating and raising the temperature is small, it is difficult to heat and raise the temperature only with the combustion heater 4.

Therefore, in this embodiment, as shown in FIG. 8, the fuel cell 1 is heated and heated by the electric heater 4a at the time of a low heat load, and only the combustion type heater 4 or the combustion type The fuel cell 1 is heated and heated by using the heater 4 and the electric heater 4a together. Thereby, the fuel cell 1 can be efficiently heated and heated.

(Other Embodiments) In the above-described embodiment, the combustion heater 4 was operated using methanol (fuel of the fuel cell 1) as a fuel.
The fuel is not limited to methanol (the fuel of the fuel cell 1) but may be a fuel such as light oil or gasoline. When using light oil, gasoline, or the like as a fuel, it is desirable to provide a filter for removing substances harmful to the fuel cell 1 contained in the combustion exhaust gas.

In the above-described embodiment, the combustion type heater 4 is used only for heating and raising the temperature of the fuel cell 1 (warming up).
It may also be used as a combustion type heater for heating the vehicle interior.
Similarly, the electric heater 4a may also be used as an electric heater for heating the passenger compartment.

[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 structural diagram of a fuel cell.

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

FIG. 4 is a flowchart showing an operation of the fuel cell system according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram of a fuel cell system according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram of a fuel cell system according to a third embodiment of the present invention.

FIG. 7 is a schematic view of a combustion heater used in a fuel cell system according to a third embodiment of the present invention.

FIG. 8 is a chart showing the operation of a combustion heater used in a fuel cell system according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 4 ... Combustion heater, 5 ... Refrigerant piping, 6 ...
Radiator, 7: bypass circuit, 8: exhaust pipe, 17: second air pump.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hirokuni Sasaki 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Nobuo Fujita 1-Toyota-cho, Toyota-shi, Aichi Prefecture Inside Toyota Motor Corporation F-term (reference) 5H027 AA02 CC02 KK46 KK48 MM16 5H115 PG04 PI16 PI18 TI10 TO05 UI30 UI35

Claims (6)

[Claims] 1. A fuel cell (1) that generates electric power by chemically reacting hydrogen and oxygen, and a combustion heater (4) that generates heat by burning fuel.
After cooling the combustion exhaust gas of the combustion type heater (4), the cooled combustion exhaust gas is guided to the fuel cell (1), and the first fuel cell heating means ( 8, 17) and a second fuel cell heating means (5) for circulating the fluid heated by the combustion heater (4) in the fuel cell (1) to heat and raise the temperature of the fuel cell (1). , 14). A fuel cell system comprising: 2. When the temperature of the fluid heated by the combustion heater (4) is lower than a predetermined temperature, the fuel cell (1) is heated by the first fuel cell heating means (8, 17). When the temperature of the fluid heated by the combustion heater (4) is equal to or higher than a predetermined temperature, the first fuel cell heating means (8,
17), the second fuel cell heating means (5, 1
The fuel cell system according to claim 1, wherein the fuel cell (1) is heated and heated in 4). 3. The first fuel cell heating means (8, 17).
3. The fuel cell system according to claim 1, wherein the fuel gas is cooled by injecting fresh air into the combustion exhaust gas. 4. 4. The first fuel cell heating means (8, 17).
The fuel cell system according to claim 1, wherein the fuel cell cools the combustion exhaust by injecting water into the combustion exhaust. 5. An electric heater (4) for heating a fluid circulated through the fuel cell (1) is provided in the combustion type heater (4).
The fuel cell system according to claim 1, wherein a) is incorporated. 6. The fuel cell according to claim 1, wherein the combustion heater (4) generates heat by burning fuel of the fuel cell (1). system.