JP2002313391A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the low temperature startability of a fuel cell. SOLUTION: Anode electrodes 2 and cathode electrodes 3 are installed on both sides of solid polymer electrolyte membranes 4, and reaction gas passages A1, A2, C1 and C2 are provided on the outside of the electrodes to form a cell 5. Electric heaters 33 are installed in coolant passages R in the partial areas of the power generating surfaces of the cell 5. When the fuel cell is started at a low temperature, the electric heaters 33 are turned ON to locally heat the cell 5 for local power generation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell having a solid polymer electrolyte membrane, and more particularly to a fuel cell having excellent low-temperature startability.

[0002]

2. Description of the Related Art In a fuel cell, a solid polymer electrolyte membrane is sandwiched between an anode electrode and a cathode electrode to form a membrane-electrode structure, and the membrane-electrode structure is sandwiched between a pair of separators. There is something. In this fuel cell, a fuel gas (for example, hydrogen gas) is supplied to a power generation surface of an anode electrode, and an oxidant gas (for example, air containing oxygen) is supplied to a power generation surface of a cathode electrode to perform a chemical reaction. Electrons are taken out to an external circuit and used as DC electric energy. At the cathode electrode, an oxidizing gas (for example,
Hydrogen-containing air)
The electrons and oxygen react to produce water. Therefore, it has attracted attention as a driving source for vehicles because it has little effect on the environment.

Generally, the operating temperature of this type of fuel cell is 7
Although the temperature is set to about 0 ° C. to 80 ° C., the power generation efficiency is reduced at low temperatures, so that the startability at low temperatures is a major problem. Therefore, when the fuel cell is used for a vehicle, there is a problem that it takes a long time to start when the outside air temperature is low, for example, when the fuel cell is started below freezing. On the other hand, for example, JP-T-2000-5120
As described in JP-A-68-68, there is a fuel cell in which the reaction is promoted by supplying electric power to an external load of the fuel cell, and the temperature is raised by self-heating to improve the startability.

[0004]

However, in the conventional technique using self-heating, for example, when the fuel cell is below freezing at startup, the entire fuel cell having a large heat capacity is heated only by self-heating. There is a problem that it takes a long time to do so. In addition, although the fuel cell is generating power in order to warm up the fuel cell, the amount of heat generated by the fuel cell itself is insufficient due to the self-heating of the fuel cell. Was.
Accordingly, the present invention provides a fuel cell which has a low temperature start-up property by promoting self-heating by locally heating a part of the power generation surface of the fuel cell by a heating means, enabling the temperature of the fuel cell to rise in a short time. Is provided.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention described in claim 1 is based on both sides of a solid polymer electrolyte membrane (for example, a solid polymer electrolyte membrane 4 in each embodiment described later). Are provided with an anode electrode (for example, an anode electrode 2 in each embodiment described later) and a cathode electrode (for example, a cathode electrode 3 in each embodiment described later), and a reaction gas passage ( For example, a fuel cell (for example, a cell 5 in each embodiment described later) provided with a cell (for example, a cell 5 in each embodiment described later) provided with fuel gas passages A1 and A2 and air passages C1 and C2 in each embodiment described later. In the fuel cell 1 according to each embodiment described above, a heating unit (for example, a first unit to be described later)
, The electric heater 53 according to the second embodiment, the catalyst 65 according to the third embodiment, and the oxidizing / reducing agent 72 according to the fourth embodiment. .

[0006] With this configuration, when the fuel cell is started at a low temperature, the heating means can quickly heat the partial area of the power generation surface, and the ion passing resistance of the solid polymer electrolyte membrane in this area can be increased. To increase the power generation efficiency, thereby promoting self-heating and quickly raising the temperature of the area. This high temperature area can be extended over the entire power generation surface to increase the temperature of the fuel cell.

According to a second aspect of the present invention, in the first aspect, the heating means is an electric heater (for example, an electric heater 3 in a first embodiment described later).
3. The electric heater 53 according to the second embodiment. With this configuration,
The heating means can be operated with electric energy.

According to a third aspect of the present invention, in the second aspect of the present invention, the cell includes a coolant passage (for example, a coolant passage R in a first embodiment described later). The passage is provided with the electric heater (for example, an electric heater 33 in a first embodiment described later). With this configuration, the electric heater can be easily attached to the cell.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the fuel cell comprises a plurality of the cells stacked, and a fastening bolt (for example, a second bolt described later) for fastening the stacked cells. The electric heater (for example, an electric heater 53 according to a second embodiment described later) is built in the stud bolt 40A according to the embodiment. With this configuration, it is possible to locally heat the periphery of the fastening bolt.

According to a fifth aspect of the present invention, in the first aspect, the heating means is a catalytic combustor (for example, a catalyst 65 in a third embodiment described later). . With this configuration,
Only by supplying an oxidizing gas (for example, oxygen or air) and a reducing gas (for example, hydrogen) to the catalytic combustor, these gases can be rapidly burned, and a part of the power generation surface can be quickly heated.

According to a sixth aspect of the present invention, in the first aspect of the invention, the heating means includes an oxidizing / reducing agent (for example, an oxidizing / reducing agent 72 in a fourth embodiment described later) which is oxidized. It is characterized by utilizing heat generated at the time of the operation. With this configuration, it is possible to quickly heat a part of the power generation surface only by supplying the oxidizing gas (for example, oxygen or air).

According to a seventh aspect of the present invention, in the first aspect of the invention, the operation of the heating means is controlled in accordance with the temperature of the fuel cell. With this configuration, the heating unit is operated only when the temperature of the fuel cell is low to locally heat a part of the power generation surface of the cell, and the operation of the heating unit is stopped when the temperature of the fuel cell is high. As a result, local heating of the cell can be stopped.

According to an eighth aspect of the present invention, in the first aspect of the invention, the operation of the heating means is controlled in accordance with the output voltage of the fuel cell. With this configuration, the heating unit is operated only when the output voltage of the fuel cell is low to locally heat a part of the power generation surface of the cell, and when the output voltage of the fuel cell is high, the heating unit is operated. To stop the local heating of the cell.

According to a ninth aspect of the present invention, in the first aspect, the fuel cell includes a plurality of the stacked cells, and controls the operation of the heating means according to the temperature of each cell. It is characterized by. With this configuration, it is possible to operate or stop the heating means according to the temperature state of each cell.

According to a tenth aspect of the present invention, in the first aspect, the fuel cell includes a plurality of the stacked cells, and controls the operation of the heating means in accordance with the output voltage of each cell. It is characterized by the following. With this configuration, the heating unit can be operated or stopped according to the state of the output voltage of each cell.

According to an eleventh aspect of the present invention, in the first aspect of the invention, the fuel cell includes a plurality of the stacked cells. It is characterized in that it is provided at a different position above. With this configuration, when current flows between the cells, current flows in a direction perpendicular to the cell stacking direction, and since the current path has electric resistance, Joule heat is generated, Heat the fuel cell.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel cell according to the present invention will be described below with reference to FIGS. Note that the fuel cell in the embodiment described below is an embodiment mounted on a fuel cell vehicle.

[First Embodiment] First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. FIG. 2 is a longitudinal sectional view of a part of the fuel cell 1. The fuel cell 1 has a cell (unit fuel cell) 15 in which a solid polymer electrolyte membrane 4 is sandwiched between an anode electrode 2 and a cathode electrode 3 and the outside thereof is sandwiched between a pair of separators 6 and 7. A plurality of fuel cells are stacked and fastened with stud bolts (not shown) to form, for example, a fuel cell stack for a vehicle. In this embodiment, a single cell 5 will be described as an example for convenience of explanation.

The solid polymer electrolyte membrane 4 uses, for example, a perfluorosulfonic acid polymer or the like. Also,
The anode electrode 2 and the cathode electrode 3 are mainly composed of platinum Pt, and are disposed on a diffusion layer made of porous carbon cloth or porous carbon paper. The separators 6 and 7 are made of dense carbon or metal, and electric power is extracted from these separators 6 and 7.

FIG. 1 is a front view of the cathode-side separator 7 as viewed from the side facing the membrane electrode assembly 5. The cathode-side separator 7 has reaction gas passages C1 and C2 partitioned into an upper half and a lower half. Here, in the case of a dense carbon separator, the reaction gas passage is constituted by a plurality of grooves. It is composed of As the reaction gas passages C1 and C2, various shapes such as a meandering passage and a U-shaped passage can be adopted. For convenience of illustration, the reaction gas passage of the separator 6 on the anode side is also indicated by a chain line.

The reaction gas passage C1 in the upper half of the separator 7 on the cathode side originates from an inlet-side oxidant gas communication hole 10 formed in the lower part of the right side of the separator 7 on the cathode side, and has a diagonal corner. It terminates in the outlet-side oxidant gas communication hole 11 arranged in the direction. Similarly, a reaction gas passage C2, an inlet-side oxidizing gas communication hole 10, and an outlet-side oxidizing gas communication hole 11 having the same configuration as the upper half are formed in the lower half of the separator 7 on the cathode side. I have. Here, each of the inlet-side oxidant gas communication holes 10 is connected to a supercharger S / C via a supply pipe (supply path) 13 and is an oxidant gas from the supercharger S / C driven by the motor m. Although air is supplied, a supply pipe 13 on the lower half side is provided with a valve 14 for shutting off the supply of air.

On the other hand, the separator 6 on the anode side also has reaction gas passages A1, A2 divided into an upper half and a lower half corresponding to the separator 7 on the cathode side. In other words, the fuel gas passages C1 and C2 on the cathode side start at the inlet-side fuel gas communication holes 20 formed in the lower part of the left side of the separator 6 on the anode side, and are arranged diagonally. Reactive gas passages A1 and A2 terminated by the outlet side fuel gas communication holes 21 are formed in the upper half and the lower half, respectively. Here, each of the inlet side fuel gas communication holes 20 is
Although connected to the hydrogen tank H2 via the supply pipe 23, the lower supply pipe 23 is provided with a valve 24 for shutting off the supply of hydrogen gas. Note that, instead of the hydrogen tank H2, a methanol tank equipped with a reformer may be used.

A pair of inlet-side coolant communication holes 30, 30 are provided on the lower sides of the anode-side separator 6 and the cathode-side separator 7, respectively. A pair of outlet-side coolant communication holes 31, 31 are formed in the sides. In the separator 6 on the anode side, a coolant passage R connecting the opposed coolant communication holes 30 and 31 is formed. The cooling liquid passage R is connected to a cooling system pipe (not shown).

The cathode electrode 3 corresponding to the upper half of the cathode-side separator 7 and the anode-side separator 6
A power generation surface of the anode electrode 2 (that is, a portion where the reaction gas passage C1 exists in FIG. 1) is configured as a local power generation region (a region indicated by a broken line in FIG. 3) S1 and both coolants in this region S1 As shown in FIG.
An electric heater (heating means) 33 is provided as shown in FIG. The electric heater 33 is constituted by a so-called thin film heater. The electric heater 33 is provided on the surface of the separator 7 on the side where the reaction gas passages C1 and C2 are not formed and at a position corresponding to the two cooling liquid passages R and R in the region S1. It is formed by appropriate means such as printing or vapor deposition.

In the fuel cell 1 formed by stacking a large number of cells 5 having the above-described structure, terminal members of one outermost cathode-side separator 7 and the other outermost anode-side separator 6 (see FIG. Fuel cell 1 (not shown)
A closed circuit for extracting an output from the fuel cell 1 is formed, and the driving motor M and the external load F (including an electric heater of an embodiment described later) are driven by the output power of the fuel cell 1.

As shown in FIG. 2, a plurality of cells 5
The separator 7 of one of the cells 5 has the area S
A temperature sensor 34 for detecting a representative temperature of the fuel cell 1 is provided at a predetermined portion (for example, at the center of the region S1) in 1. The temperature sensor 34 is composed of, for example, a thermistor, and an output signal of the temperature sensor 34 is input to the fuel cell control ECU 50. Furthermore, this fuel cell 1
In, in order to detect the output voltage of each cell 5, a voltage sensor 36 is connected to the separators 6, 7 of each cell 5, and an output signal of the voltage sensor 36 is input to the ECU 50.

The ECU 50 is provided with the hydrogen tank H
2. The motor m of the supercharger S / C, the valve 24 of the supply pipe connected to the hydrogen tank H2, and the valve 14 of the supply pipe 13 connected to the supercharger S / C. The ECU 50 is operated by electric power stored in a battery (not shown) when the fuel cell 1 is started.

The fuel cell 1 thus configured operates as follows in the full power generation mode. In the full power generation mode, hydrogen gas and air flow through both the upper and lower reaction gas passages A1 and A2 and the reaction gas passages C1 and C2, and the coolant flows through both the left and right cooling liquid passages R and R. That is, hydrogen gas is supplied to the inlet side fuel gas communication hole 20 to flow the hydrogen gas through the reaction gas passages A1 and A2, and is discharged to the outlet side fuel gas communication hole 21. In addition, the supercharger S / C is driven to supply air to the inlet-side oxidant gas communication hole 10, flow air through the reaction gas passages C1 and C2, and discharge the air to the outlet-side oxidant gas communication hole 11. Further, the coolant is supplied to the inlet-side coolant communication hole 30 to flow the coolant upward through the coolant passages R, R, and is discharged to the outlet-side coolant communication hole 31. As a result, power is generated on the entire power generation surface of all the cells 5.

As described above, in a fuel cell provided with a solid polymer electrolyte membrane, the power generation efficiency is reduced when the temperature is low, as described above. In addition, if the outside air temperature is below freezing (for example, -10
At low temperatures such as (.degree. C.), the water generated in the fuel cell 1 that could not be completely removed at the time of shutdown is often frozen in a part of the grooves of the reaction gas passages C1, C2, A1, and A2. . If the fuel cell 1 is started in the full power generation mode when the fuel cell 1 is started under such conditions, it takes a long time for the temperature of the fuel cell 1 to rise.

Therefore, when the fuel cell 1 is started at such a low temperature, the fuel cell 1 is operated in the local power generation mode in order to raise the temperature of the fuel cell 1 quickly. Is shifted to the full power generation mode. In the local power generation mode, the cooling liquid does not flow through the two cooling liquid passages R, and the hydrogen gas flows only through the upper half side reaction gas passage A1 by closing the valve 24 of the hydrogen supply system. When the valve 14 of the air supply system is closed, air flows only into the upper half-side reaction gas passage C1 and does not flow into the lower half-side reaction gas passage C2. Then, the electric heater 33 is turned on. This way,
In each cell 5, only the local power generation area S1 on the upper half side serves as a power generation surface, and the lower half side of each cell 5 can be prevented from contributing to power generation.

Then, when an electric current is applied to the electric heater 33, the electric heater 33 generates heat, and the heat is passed through the separators 6, 7 to the anode electrode 2, the cathode electrode 3,
Heat is transferred to the solid polymer electrolyte membrane 4 and these are quickly heated. As a result, local power generation is rapidly performed in the region S1. In addition, the rapid generation of electricity promotes self-heating due to the reaction, and the electric heater 3
3, the temperature of the local power generation region S1 is quickly increased by the self-heating.

Here, the electric heater is set so that the sum of the heat of reaction at the time of power generation and the heat of external assist by the electric heater 33 is larger than the sum of the heat and heat radiation required for preventing freezing of generated water generated by power generation. By controlling the calorific value of 33, freezing of the generated water can be prevented. In other words, before the operation of the fuel cell 1 is stopped due to a voltage drop due to the freezing of the generated water (that is, before the output voltage of the fuel cell 1 drops to the operation limit voltage), the local power generation region S1 of each cell 5 Can be raised to 0 ° C. or higher. As a result, power generation in the local power generation region S1 can be continued, and power generation can be continued as a whole of the fuel cell 1 even when other parts (for example, the lower half of the cell 5) are below freezing. Become.

Further, the heat generated by the local heat generation in the local power generation region S1 and the heat generated by the electric heater 33 also transfers to the periphery of the local power generation region S1, and as shown in FIG. The lower half of the fuel cell 1 is also gradually heated, so that the fuel cell 1 can be heated earlier.

Further, since the power generation in the local power generation region S1 can be maintained, the minimum energy required for the operation of the fuel cell 1 (that is, the electric power required for the operation of auxiliary equipment such as a supercharger) is saved. Power generation. In the local power generation mode, only the local power generation region S1 needs to be kept in a state where power can be generated. Therefore, compared to a case where the entire surface of the cell 5 is heated by the electric heater 33, only a small energy is required. , Power consumption in the device can be suppressed.

Further, before starting at low temperature, a pre-processing (for example,
When performing purging in the reaction gas passages C1 and C2 and preheating by the electric heater 33 before the start-up, etc., only the local power generation region S1 needs to be in a startable state. Can be reduced.

Next, an example of the startup control of the fuel cell 1 is shown in FIG.
This will be described with reference to the flowchart of FIG. First, in step S101, it is determined whether or not the ignition switch is ON. The determination result of step S101 is “YES”
If it is (ignition switch ON), the process proceeds to step S102, and the determination result of step S101 is “N”.
If it is "O" (ignition switch OFF), the execution of this routine is temporarily ended.

After performing a system check in step S102, the flow advances to step S103 to determine whether there is any abnormality in the system. If the determination result of step S103 is “YES” (no abnormality), step S10
The process proceeds to step S4, and when the result of the determination in step S103 is "NO" (abnormal), the process proceeds to step S105. In step S104, it is determined whether or not the internal representative temperature of the fuel cell 1 detected by the temperature sensor 34 is lower than 0 ° C. If the determination result in step S104 is “NO” (0 ° C. or more), the process proceeds to step S106, and shifts to the full power generation mode. If the determination result of step S104 is “YE
S ”(less than 0 ° C.), the process proceeds to step S107, and shifts to the local power generation mode.

In the local power generation mode in step S107, as described above, the coolant is not supplied to the two coolant passages R, and the electric heaters 33 of all the cells 5 are turned on to heat the local power generation region S1. The local power generation in the local power generation region S1 is performed by supplying hydrogen gas and air only to the reaction gas passage A1 and the reaction gas passage C1 on the upper half side of the cell 5.

Then, in step S108, it is determined whether or not the internal representative temperature of the fuel cell 1 is lower than a set temperature of 0 ° C. or more (for example, 2 ° C.).
If it is “S” (less than 2 ° C.), the process returns to step S107. If the determination result is “NO” (2 ° C. or more), the process proceeds to step S106. That is, while the internal representative temperature of the fuel cell 1 is lower than the set temperature (2 ° C.), the operation of the fuel cell 1 in the local power generation mode is continued, and the internal representative temperature of the fuel cell 1 becomes the set temperature (2 ° C.). If the temperature rises above, the local power generation mode is terminated and the mode shifts to the full power generation mode. Upon termination of the local power generation mode, the electric heater 33 is turned off.

In the full power generation mode in step S106,
As described above, the coolant flows through both coolant passages R, R,
Hydrogen gas flows through both reaction gas passages A1 and A2 of each cell 5 and air flows through both reaction gas passages C1 and C2, and power generation is performed using the entire power generation surface of all cells 5. When the process proceeds to step S105, the process proceeds to the abnormality processing mode, and
The execution of this routine ends once.

In the start control, it is determined whether to proceed to the local power generation mode and to shift to the full power generation mode based on the internal representative temperature of the fuel cell 1.
Instead of this, it may be determined whether to proceed to the local power generation mode or to transition to the full power generation mode based on the total output voltage of the fuel cell 1.

In the start-up control, when the operation proceeds to the local power generation mode, the electric heaters 33 of all the cells 5 are turned off.
N, the local power generation region S1 of all the cells 5 is heated, but in the present invention, each cell 5 is
It may be determined whether or not the electric heater 33 of the module is turned on, or whether or not the electric heater 33 of the module is turned on for each module with a plurality of cells 5 as one module. By doing so, the cells 5 that need to be heated by the electric heater 33 can be narrowed down, so that the energy consumed in the local power generation mode can be reduced.

To determine whether or not to turn on the electric heater 33 for each cell 5, for example, a temperature sensor 34 is provided for each cell 5 and the temperature of the local power generation region S1 is set to 0.
The electric heater 33 of the cell 5 is turned ON only for the cell 5 determined to be lower than ゜ C, and the electric heater 33 is turned OFF when the temperature of the local power generation region S1 of the cell 5 becomes 2 ° C or more. To

The electric heater 33 is provided for each module.
When it is determined whether or not to turn ON, for example, a temperature sensor 34 is provided for each module, and only the module for which the temperature of the local power generation region S1 is determined to be less than 0 ° C. The electric heaters 33 of all the cells 5 are turned on, and the electric heaters 33 of the modules are turned off when the temperature of the local power generation region S1 of the module becomes 2 ° C. or more.

Further, when the temperature sensor 34 is provided for each cell 5 or each module as described above, the electric heater 33 is operated in the following power saving mode in accordance with the remaining power of the battery (not shown). May be performed. First, when the mode is shifted to the local power generation mode, it is determined whether or not enough power remaining in the battery (not shown) to maintain the operation of the fuel cell 1 even when all the electric heaters 33 are turned on, If the electric heater 33 remains, the electric heater 33 is controlled by the normal control method. If the electric heater 33 does not remain, the electric heater 33 is controlled in the power saving mode.

In the power saving mode, for example, a voltage drop rate is calculated for each cell 5. When the control is performed for each cell 5, only the electric heater 33 of the cell 5 whose voltage drop rate is positive (voltage drop) is turned on, and the voltage drop rate is negative (voltage drop does not occur). The electric heater 33 of the cell 5 is turned off. When the control is performed for each module, for a module having at least one cell 5 whose voltage drop rate is positive (voltage drop), the electric heaters 33 of all the cells 5 of the module are turned on, and the module is turned on. For the module whose voltage drop rate of all the cells 5 is positive, the electric heaters 33 of all the cells 5 of the module are turned off. With this configuration, the energy consumed in the local power generation mode can be further reduced.

In the fuel cell 1, the electric heaters 3 are provided in all of the regions corresponding to the overlapping portions of the reaction gas passages A1 and C1 in the two coolant passages R, R.
3 is provided as the local power generation region S1, but the electric heater 33 may be provided only in a part (for example, the center) of the region corresponding to the overlapping portion, and only this part may be used as the local power generation region. It is possible. Further, the installation position of the electric heater 33 is not limited to the coolant passage R, but may be embedded in each passage separator 6, 7.

Further, in the above-described embodiment, in the local power generation mode, the hydrogen gas and the air are allowed to flow only through the reaction gas passages A1 and C1 on the upper half side. The hydrogen gas may flow through both the reaction gas passages A1 and A2, and the air may flow through both the upper and lower reaction gas passages C1 and C2. As described above, when the reaction gas is supplied to the entire power generation surface, first, the local power generation region S1 on the upper half side whose temperature has been increased by the electric heater 33 is used.
As the self-generated heat generated by this power generation and the heat generated by the heating of the electric heater 33 spread to the power generation surface in the lower half and the temperature in the lower half also rises, power generation also occurs in the power generation surface in the lower half. To start.

Further, in the above-described embodiment, the reaction gas passages A1, A2, C1, and C2 are linear passages extending in the horizontal direction, respectively.
2, C1 and C2 are not limited to straight passages. For example, as shown in FIG. 6, the inlet-side oxidant gas communication hole 10 is located on the upper left side, and the outlet-side oxidant gas communication hole 11 is located on the right side. The reactant gas passages A1 and C1 may be meandered with the inlet side fuel gas communication hole 20 positioned at the upper right side and the outlet side fuel gas communication hole 21 positioned at the lower left side. In this case, the reaction gas flows so as to descend while meandering in the reaction gas passages A1 and C1.

In this case, the area where the electric heater 33 is provided in the two coolant passages R, that is, the local power generation area S1 is, for example, as shown by a two-dot chain line in FIG. It can be set to a region corresponding to a portion where the upper horizontal portion overlaps. In addition,
The setting of the local power generation region S1 is not limited to this, and can be set to a wider range or a narrower range. Even if you do this,
The same operation and effect as described above can be obtained.

[Second Embodiment] Next, a fuel cell according to a second embodiment of the present invention will be described with reference to FIGS. The difference between the fuel cell of the second embodiment and the fuel cell of the first embodiment lies in the installation location of the electric heater. In the first embodiment, the electric heater 33 is used.
Is provided in a part of the coolant passage R. However, in the second embodiment, an electric heater is not provided in the coolant passage R, and an electric heater is built in a stud bolt for tightening a large number of stacked cells. Let me.

More specifically, FIG. 7 is a front view of the separator 7 on the cathode side, and the same parts as those in the first embodiment are denoted by the same reference numerals. In the fuel cell 1 according to the second embodiment, stud bolts (tightening bolts) 40 arranged at three places at the upper part and three places at the lower part are used.
All stacked cells are tightened. Of the six stud bolts 40, only the stud bolt 40A arranged at the upper center has an electric heater.

FIG. 8 is a cross-sectional view of the stud bolt 40A. An insulating layer 52 is provided on the outer periphery of the base material 51 of the stud bolt 40A, and an electric heater (heating means) 53 is provided on the outer periphery of the insulating layer 52. An insulating layer 54 is provided on the outer periphery of the electric heater 53. The insulating layers 52 and 54
In order to ensure insulation between the electric heater 53 and the base material 51 and the outside (such as the fuel cell 1) and to have durability, it is made of a glass fiber based Teflon (registered trademark) resin or the like. A temperature sensor 55 is embedded in the outer insulating layer 54. The temperature sensor 55 and the electric heater 53 are connected to a temperature controller 56. The temperature controller 56 keeps the surface temperature of the stud bolt 40A, that is, the surface temperature of the insulating layer 54 always within a predetermined temperature range (for example, 50 to 70 °). C) so that the electric heater 53
Control.

In the second embodiment, the electric heater 53 of the stud bolt 40A is turned on in the local power generation mode to heat the stud bolt 40A, so that the area around the stud bolt 40A in each cell 5 is heated. Then, the area near the stud bolt 40A can be set as the local power generation area S2. In the case of the second embodiment, the electric heater 53 quickly raises the temperature of the power generation surface of the local power generation region S2 to generate a high-temperature portion, and local power generation starts from the local power generation region S2. The high-temperature portion gradually spreads over the entire power generation surface on the upper half side by heat conduction, and local power generation is performed on the entire power generation surface on the upper half side. Therefore, also in the fuel cell 1 of the second embodiment, the same operation and effect as those of the first embodiment can be obtained.

The fuel cell 1 according to the second embodiment is not limited to the above-described example. For example, the number of stud bolts 40A including the electric heater 53 may be changed depending on the total number and arrangement of the stud bolts 40. Two or more bolts may be set, and the position of the stud bolt 40A may be set appropriately. Further, also in the fuel cell 1 of the second embodiment, the passage form of the reaction gas passage can be a passage form other than a horizontal straight line (for example, a meandering passage shown in FIG. 6).

[Third Embodiment] Next, a third embodiment of the fuel cell according to the present invention will be described with reference to FIGS. 9 and 10. FIG. The fuel cell of the third embodiment differs from that of the first embodiment in the means for locally heating the cells 5. In the case of the first embodiment described above, the electric heater 3
3 is provided and the cell 5 is locally heated by passing an electric current through the electric heater 33. In the third embodiment, instead of providing the electric heater in the coolant passage R, a predetermined portion of the cell 5 is provided. A catalytic combustor was provided, and the vicinity of the catalytic combustor in the cell 5 was locally heated by catalytic combustion of hydrogen and oxygen in the air in the catalytic combustor. Hereinafter, this will be described in detail.

FIG. 9 is a longitudinal sectional view of a part of the fuel cell 1 according to the third embodiment, and corresponds to FIG. 2 in the first embodiment. The basic configuration of the fuel cell 1 is the same as that of the first embodiment in the third embodiment, and the same reference numerals are given to the same parts in FIG. FIG. 10 is a front view of the anode-side separator 6 as viewed from the side where the coolant passage R is formed.

As in the fuel cell 1 of the first embodiment, the fuel cell 1 has an inlet-side oxidant gas communication hole 10, an outlet-side oxidant gas communication hole 11, an inlet-side fuel gas communication hole 20, and an outlet. The fuel gas communication hole 21, the inlet-side coolant communication hole 30, and the outlet-side coolant communication hole 31 are provided.
Are provided with coolant passages R, R on one surface thereof. Although not shown in FIG. 10, the reaction gas passages A1 and A2 are provided on the other surface of the separator 6, and the reaction gas passages C1 and C2 are provided in the separator 7. This is the same as the embodiment.

In the fuel cell 1 of the third embodiment, two communication holes are further provided between the outlet-side fuel coolant communication holes 31 and 31 through the cell 5, and the inlet-side coolant communication is provided. One communication hole is provided between the holes 30, 30 so as to penetrate the cell 5. One of the two communication holes provided in the upper portion is a hydrogen gas communication hole 61 for supplying hydrogen gas, and the other is an air communication hole 62 for supplying air. The one communication hole provided in the lower part is an exhaust communication hole 63 for discharging combustion gas.

Further, the separator 6 in each cell 5 has the same surface as the surface on which the cooling liquid passages R, R are provided, and between the cooling liquid passages R, R, the hydrogen gas communication hole 61 and the air communication. Gas passage 64 connecting hole 62 and exhaust communication hole 63
Is provided. The gas passage 64 is provided with the hydrogen gas communication hole 6.
The gas passage connected to 1 and the gas passage connected to the air communication hole 62 are merged, and the gas passage after the merge is connected to the exhaust passage 63. The wall surface of the junction (the hatched portion in FIG. 10) A catalyst (catalytic combustor, heating means) 65 for reacting hydrogen with oxygen in the air is attached. Further, one of the plurality of separators 7 is provided with a temperature sensor 69 for detecting a representative temperature of the fuel cell 1 at a position corresponding to the vicinity of the portion where the catalyst 65 is attached. The temperature sensor 69 is formed of, for example, a thermistor, and an output signal of the temperature sensor 69 is input to the fuel cell control ECU 50.

The hydrogen gas communication hole 61 is connected to a hydrogen supply device 67 via a control valve 66, and the air communication hole 62 is connected to an air supply device 68. The control valve 66, the hydrogen supply device 67, the air supply device 68 is a fuel cell control ECU 50
Is controlled by In the above-described first embodiment, the cell 5 is locally heated by turning on the electric heater 33 in the local power generation mode at the time of low-temperature startup. However, in the fuel cell 1 of the third embodiment, the low-temperature startup is performed. In the local power generation mode at the time, hydrogen gas is supplied from the hydrogen supply device 67 to the hydrogen gas communication hole 61, air is supplied from the air supply device 68 to the air communication hole 62, and each cell 5 is supplied from the communication hole 61, 62. The hydrogen gas flowing into the gas passage 64 and the oxygen in the air are caused to react by the catalyst 65 at the junction, and the reaction heat locally heats the vicinity of the junction. Thus, also in the third embodiment, it is possible to form the local power generation region S3 in each cell 5,
The same operation and effect as those of the first embodiment can be obtained.

Moreover, in the fuel cell 1 according to the third embodiment, since the hydrogen gas and the oxygen in the air are catalytically combusted, a large heat energy can be obtained and the temperature rise rises quickly. , Electric heater 3
Heating faster than 3 is possible. Further, since hydrogen is also a fuel of the fuel cell 1, the fuel can be unified, and
There is also an advantage that the device configuration becomes easy.

Next, an example of the startup control of the fuel cell 1 according to the third embodiment will be described with reference to the flowchart of FIG. Steps S201 to S205 are the same as steps S101 to S105 in the startup control according to the first embodiment, and thus description thereof is omitted. In the third embodiment, step S2
If the determination in step 04 is negative and the process proceeds to step S206 to enter the full power generation mode, the supply of combustion hydrogen from the hydrogen supply device 67 to the hydrogen gas communication hole 61 is stopped, and the air supply from the air supply device 68 is stopped. The supply of air to the communication hole 62 is stopped. Then, the coolant flows through both the coolant passages R, R, the hydrogen gas flows through the reaction gas passages A1, A2 of each cell 5, the air flows through the reaction gas passages C1, C2, and the entire power generation surface of all the cells 5 Use to generate electricity.

On the other hand, if the result of the determination in step S204 is affirmative and the process proceeds to step S207 and the local power generation mode is set, the coolant is not supplied to the coolant passages R, and the reactant gas in the upper half of each cell 5 is not supplied. Hydrogen gas and air are supplied only to the passages A1 and C1. Further, by supplying air for combustion from the air supply device 68 to the air communication hole 62 and supplying hydrogen gas for combustion from the hydrogen supply device 67 to the hydrogen gas communication hole 61, the local power generation in the local power generation region S3 is achieved. Execute The supply amount of the combustion hydrogen is determined by the ECU 50 according to the representative internal temperature of the fuel cell 1 with reference to a map prepared in advance.
0 executes the flow rate control by the control valve 66.

Then, in step S208, it is determined whether or not the internal representative temperature of the fuel cell 1 is lower than a set temperature of 0 ° C. or higher (for example, 2 ° C.), and the determination result is “YE
S ”(less than 2 ° C.), the flow returns to step S207 to continue the local power generation mode, and the determination result is“ NO ”(2
If (゜ C or more), the process proceeds to the full power generation mode in step S206.

In the starting control, it is determined whether or not to proceed to the local power generation mode and whether to shift to the full power generation mode based on the internal representative temperature of the fuel cell 1.
Instead of this, it may be determined whether to proceed to the local power generation mode or to transition to the full power generation mode based on the total output voltage of the fuel cell 1. In the start-up control, when the internal representative temperature of the fuel cell 1 is higher than 0 ° C., the mode shifts to the full power generation mode. However, when the internal representative temperature of the fuel cell 1 is 0 ° C. or higher, However, when the temperature is in a relatively low temperature range (for example, 15 ° C. or lower), a slight warm-up is performed by supplying a small amount of combustion hydrogen and combustion air to the gas passage 64. It is also possible to promote the temperature rise of the fuel cell 1. Furthermore, the execution condition of the slight warm-up may be weighted by the fact that there is a voltage drop in any of the cells 5.

In the third embodiment, when in the local power generation mode, the upper half reaction gas passages A1, C
1, the hydrogen gas and the air flow only in the first and second reaction gas passages A1 and A2 in the local power generation mode.
Hydrogen gas through the upper and lower reaction gas passages C1 and C2.
It is the same as in the first embodiment that the air may be supplied to the air. Also in the fuel cell 1 of the third embodiment, as in the case of the first embodiment,
The passage form of the reaction gas passage can be a passage form other than a horizontal straight line (for example, a meandering passage shown in FIG. 6).

[Fourth Embodiment] Next, a fuel cell according to a fourth embodiment of the present invention will be described with reference to FIGS. The configuration of the fuel cell according to the fourth embodiment is very similar to that of the third embodiment. In the third embodiment, a catalytic combustor is provided at a predetermined portion of the cell 5, and in this catalytic combustor, the cell 5 is locally heated by catalytic combustion of hydrogen and oxygen in the air. In the fourth embodiment, an oxidizing / reducing agent is provided at a predetermined portion of the cell 5, and the cell 5 is locally heated by utilizing heat generated when the oxidizing / reducing agent is oxidized by oxygen. ing.

FIG. 12 is a longitudinal sectional view of a part of the fuel cell 1 according to the fourth embodiment, and is a view corresponding to FIG. 9 in the third embodiment. Are denoted by the same reference numerals. FIG. 13 is a front view of the separator 6 in the fourth embodiment as viewed from the side where the coolant passage R is formed, and is a view corresponding to FIG. 10 in the third embodiment. The same parts as those in FIG. 10 are denoted by the same reference numerals.

In the fuel cell 1 according to the fourth embodiment, one communication hole is provided between the outlet side coolant communication holes 31 and 31 so as to penetrate the cell 5. A hydrogen supply device 67 and an air supply device 68 are connected to a communication hole 70. The separator 6 has a gas communication hole 70 and an exhaust communication hole 63 between the coolant passages R, R.
Is provided, and a gas passage 71 is provided.
1 upstream part (that is, a part close to the gas communication hole 70)
As shown by hatching in FIG. 13, an oxidizing / reducing agent (heating means) 72 is attached to the wall surface.

In the above-described third embodiment, in the local power generation mode at the time of low-temperature start-up, hydrogen gas and air are simultaneously supplied to the gas passage 64, and the hydrogen gas and oxygen in the air are reacted by the catalyst 65 at the junction. The cell 5 was locally heated by the reaction heat. However, this fourth
In the embodiment, only the air is supplied from the air supply device 68 to the gas communication hole 70 and the hydrogen gas is not supplied to the gas communication hole 70 in the local power generation mode at the time of low temperature startup. This way,
The air supplied to the gas passage 70 is supplied to the gas passage 7 of each cell 5.
1 and the oxidizing / reducing agent 7 in the upstream portion of the gas passage 71.
2 generates heat when it oxidizes by reacting with oxygen in the air, and this reaction heat locally heats the vicinity of the upstream portion of the gas passage 71. Thus, also in the fourth embodiment, the local power generation region S4 can be formed in each cell 5, and the same operation and effect as in the third embodiment can be obtained.

In the fourth embodiment, the supply of air to the gas communication holes 70 is stopped when the local power generation mode ends, and a predetermined amount of hydrogen gas is supplied from the hydrogen supply device 67 to the gas communication holes 70. I do. As a result, the oxidizing / reducing agent 72 reacts with hydrogen, is reduced and returns to its original state, and absorbs heat at this time.

[Fifth Embodiment] Next, a fuel cell according to a fifth embodiment of the present invention will be described with reference to FIGS. 14 and 15. FIG. In each of the embodiments described above,
In all the cells 5 constituting the fuel cell 1, the local power generation regions S1 to S4 are provided at the same position when viewed from the front of the power generation surface. On the other hand, in the fifth embodiment, FIG.
4. As shown in FIG. 15, the position of the local power generation region S is provided at a different position on the power generation surface between the adjacent cells 5. In this way, when a current flows between the cells 5 and 5 in the local power generation mode, a current flows in the separators 6 and 7 in a direction perpendicular to the stacking direction of the cells 5 as indicated by arrows in FIG. As a result, Joule heat is generated due to the loss of the electrical resistance of the separators 6 and 7, and the warm-up of the fuel cell 1 can be further promoted.

Although the method of forming the local power generation region S in the fifth embodiment is not particularly limited, a part of the separator (such as a coolant passage) as in the first embodiment described above.
A method of providing an electric heater is particularly preferable, and
As in the third and fourth embodiments, a method in which a catalytic combustor or an oxidizing / reducing agent is provided in the cell 5 is also possible. Further, the positions of the local power generation regions S of all the adjacent cells 5 may be different, or the positions of the local power generation regions S may be different for each module.

[0075]

As described above, according to the first aspect of the present invention, when the fuel cell is started at a low temperature, a part of the power generation surface can be quickly heated by the heating means. In order to increase the power generation efficiency by lowering the ion passing resistance of the solid polymer electrolyte membrane in the above, the self-heating is promoted and the temperature of the region concerned is quickly raised, and this high temperature region is expanded to the entire power generation surface, and the fuel cell Since the temperature of the fuel cell can be increased, the start-up time can be shortened as compared with the case where the entire power generation surface is heated by self-heating, and there is an effect that the low-temperature startability of the fuel cell can be improved.

According to the second aspect of the invention, there is an effect that the heating means can be operated by electric energy. According to the invention described in claim 3, there is an effect that the electric heater can be easily attached to the cell. According to the invention described in claim 4, the periphery of the fastening bolt can be a local power generation unit.

According to the fifth aspect of the present invention, it is possible to quickly burn these gases by simply supplying the oxidizing gas and the reducing gas to the catalytic combustor and quickly heat a part of the power generation surface. This has the effect of simplifying the configuration of the heating means. In addition, since rapid heating can be realized, the temperature rise of the fuel cell can be further accelerated, and there is an effect that the low-temperature startability of the fuel cell can be further improved.

According to the sixth aspect of the present invention, it is possible to quickly heat a part of the power generation surface only by supplying the oxidizing gas, so that the structure of the heating means is simplified. In addition, since rapid heating can be realized, the temperature rise of the fuel cell can be further accelerated, and there is an effect that the low-temperature startability of the fuel cell can be further improved.

According to the invention described in claim 7, the heating means is operated only when the temperature of the fuel cell is low to locally heat the cell, and when the temperature of the fuel cell is high, the operation of the heating means is stopped. As a result, the local heating of the cell can be stopped, so that there is an effect that energy consumption can be reduced.

According to the present invention, the heating means is operated only when the output voltage of the fuel cell is low to locally heat the cell, and when the output voltage of the fuel cell is high, the heating means is operated. Can be stopped to stop local heating of the cell, so that there is an effect that energy consumption can be reduced.

According to the ninth aspect of the present invention, since the heating means can be activated or deactivated according to the temperature condition of each cell, the effect of reducing energy consumption can be obtained. is there. According to the tenth aspect of the present invention, since the heating means can be operated or stopped according to the state of the output voltage of each cell, there is an effect that energy consumption can be reduced. .

According to the eleventh aspect of the present invention, when a current flows between cells provided with different heating means, a current flows in a direction perpendicular to the cell stacking direction. Since the current path has electric resistance, Joule heat is generated, and the fuel cell is also heated by the Joule heat, so that the temperature rise of the fuel cell can be further accelerated, and the low-temperature startability of the fuel cell can be improved. Has the effect of being able to further increase

[Brief description of the drawings]

FIG. 1 is a front view of a separator in a first embodiment of a fuel cell according to the present invention.

FIG. 2 is a longitudinal sectional view of the fuel cell according to the first embodiment.

FIG. 3 is a view showing a state in which a heating portion is expanded in the fuel cell according to the first embodiment.

FIG. 4 is a diagram showing a state in which a heating portion is expanded in the fuel cell according to the first embodiment.

FIG. 5 is a flowchart illustrating an example of start control in the fuel cell according to the first embodiment.

FIG. 6 is a front view of a separator in a modification of the fuel cell according to the first embodiment.

FIG. 7 is a front view of a separator in a second embodiment of the fuel cell according to the present invention.

FIG. 8 is a sectional view of a stud bolt in the fuel cell according to the second embodiment.

FIG. 9 is a longitudinal sectional view of a fuel cell according to a third embodiment of the present invention.

FIG. 10 is a front view of a separator in the fuel cell according to the third embodiment.

FIG. 11 is a flowchart illustrating an example of start control in the fuel cell according to the third embodiment.

FIG. 12 is a longitudinal sectional view of a fuel cell according to a fourth embodiment of the present invention.

FIG. 13 is a front view of a separator in the fuel cell according to the fourth embodiment.

FIG. 14 is a front view showing a positional relationship of a local power generation region S between adjacent cells in a fifth embodiment of the fuel cell according to the present invention.

FIG. 15 is a cross-sectional view showing a state of a current flowing between adjacent cells in the fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Anode electrode 3 Cathode electrode 4 Solid polymer electrolyte membrane 5 Cell A1, A2, C1, C2 Reaction gas passage R, R Coolant passage 33 Electric heater (heating means) 40A Stud bolt (tightening bolt) 53 Electric heater (Heating means) 65 Catalyst (Catalyst combustor, heating means) 72 Oxidizing / reducing agent (Heating means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01M 8/10 H01M 8/10 8/24 8/24 Z F-term (Reference) 5H026 AA06 CC03 CV00 5H027 AA06 CC00 CC06 CC11 KK46 KK54 MM00 MM16 MM21

Claims (11)

[Claims] 1. A fuel cell comprising a cell in which an anode electrode and a cathode electrode are provided on both sides of a solid polymer electrolyte membrane, and a reaction gas passage is provided outside each of the electrodes. A fuel cell comprising a heating means in a partial area of a surface. 2. The fuel cell according to claim 1, wherein said heating means is an electric heater. 3. The fuel cell according to claim 2, wherein the cell has a coolant passage, and the electric heater is provided in the coolant passage. 4. The fuel cell according to claim 2, wherein the fuel cell is formed by laminating a plurality of the cells, and the electric heater is built in a fastening bolt for fastening the laminated cells. 5. The fuel cell according to claim 1, wherein said heating means is a catalytic combustor. 6. The fuel cell according to claim 1, wherein the heating means uses heat generated when the oxidizing / reducing agent is oxidized. 7. The fuel cell according to claim 1, wherein the operation of the heating unit is controlled according to the temperature of the fuel cell. 8. The fuel cell according to claim 1, wherein the operation of the heating means is controlled according to the output voltage of the fuel cell. 9. The fuel cell according to claim 1, wherein the fuel cell is formed by stacking a plurality of the cells, and controls the operation of the heating unit according to the temperature of each cell. 10. The fuel cell according to claim 1, wherein the fuel cell is formed by stacking a plurality of the cells, and controls the operation of the heating means according to the output voltage of each cell. 11. The fuel cell according to claim 1, wherein a plurality of the cells are stacked, and in at least one pair of adjacent cells, the heating means are provided at different positions on a power generation surface. Item 2. The fuel cell according to Item 1,