JP2002280039A - Fuel cell cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fluctuation of a round level of a car body caused by liquid junction of a fuel cell by coolant. SOLUTION: This fuel cell cooling device 1 is furnished with a fuel cell storage case to store the fuel cell in thermal insulation and/or in electric insulation, a heat exchanging means 4 to cool the coolant to cool the fuel cell 3 stored in the fuel cell storage case 6 outside of the fuel cell storage case 6 and a coolant circulating line 5 connecting the fuel cell 3 and the heat exchanging means 4 to each other through a wall surface of the fuel cell storage case 6 and circulate the coolant between the fuel cell 3 and the heat exchanging means 4, and a pair of through parts 7 through which the coolant circulating line 5 passes the fuel cell storage case 6 is connected to a ground of a control device of the fuel cell 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell cooling device for cooling a cooling liquid flowing through a fuel cell.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, a fuel cell 50 has a hydrogen permeable membrane 51 and catalyst electrodes 52 on both sides thereof.
An electrode membrane structure (MEA) 56 composed of a plurality of unit cells 59 is sandwiched between a pair of separators 57 and 58 via gas diffusion layers 54 and 55 to form a plurality of unit cells 59. Gas diffusion layers 54 and 55 of each unit cell 59
Defines an anode gas passage 60 through which a fuel gas (eg, hydrogen gas) flows and a cathode gas passage 61 through which an oxidizing gas (eg, air containing oxygen) flows. The fuel gas guided to the anode gas diffusion layer 54 is ionized on the electrode reaction surface of the catalyst electrode 52. Thus, the extracted electrons can be used as DC electric energy.

[0003] Each of the separators 57, 58 is provided with a coolant (for example, pure water) which penetrates through the separators 57, 58 and suppresses heat generated when the fuel gas is ionized.
Is defined in the cooling liquid passage 62 through which the cooling fluid flows. Also,
Adjacent separators 57, 58 of adjacent unit cells 59
Between them, a coolant flow groove 63 communicating with the coolant channel 62 is formed.

[0004] These coolant flow channels 62 and coolant flow grooves 63 are formed in adjacent separators 5 of adjacent unit cells 59.
Sealed to the outside by a waterproof seal 64 disposed between the cells 7 and 58 and a waterproof and insulating pole seal 65 disposed between the separators 57 and 58 of each unit cell 59. FIG. 5 shows the cooling liquid passage 62 of each unit cell 59.
As shown in the figure, the radiator 66 outside the fuel cell 50
Coolant circulation line 6 for circulating coolant between
7 is connected. The cooling liquid heated in the unit cell 59 enters the radiator 66 through the cooling liquid circulation line 67, and after being cooled there, can flow through the cooling liquid flow path 62 in the unit cell 59 again. I have.

[0005] The fuel cell 50 is housed in a fuel cell housing case 68 made of, for example, an insulating material to keep the fuel cell 50 warm and / or insulated, while the radiator 66 is mounted in the fuel cell housing case. It is arranged outside 68 and exchanges heat with the outside air. Therefore, the coolant circulation line 67 is connected to the fuel cell 5
At a position on the way from 0 to the radiator 66 and a position on the way from the radiator 66 to the fuel cell 50, they penetrate the wall surface of the fuel cell storage case 68.

In this case, the coolant circulation line 67
The coolant circulated through the inside is always in contact with the channel wall surface of the coolant channel 62 in the unit cell 59, the channel wall surface in the radiator 66, and the like. The radiator is generally made of a metal having a high thermal conductivity in order to ensure high heat dissipation performance. For this reason, as the coolant circulates through the coolant circulation line 67, metal ions dissolve into the coolant from these metal parts, and the conductivity of the coolant increases.

Further, since the space between the flow path wall of the unit cell 59 and the coolant is not electrically insulated, the coolant circulation line 6
The rise in the conductivity of the coolant flowing through the separator 7 causes the separators 57 and 58 in each unit cell 59 electrically insulated by the inter-electrode seal 62 to be electrically connected via the coolant. A so-called "liquid junction" phenomenon. This liquid junction phenomenon is equivalent to connecting the separators 57 and 58 with the resistor 69 as schematically shown in FIG.

When the conductivity of the coolant increases in the presence of such a liquid junction phenomenon, a potential distribution occurs along the coolant circulation line 67. That is, as shown in FIG. 6, assuming that the distance along the circulation line from the positive electrode of the fuel cell 50 is L, the potential of the coolant circulation line 67 gradually decreases from the positive electrode and connects to the ground with the control device. Ground potential at the position of the radiator 66,
Further, it gradually decreases to the negative electrode of the fuel cell 50. For example, one connection flange 70 of the coolant circulation line 67
Is at the potential Va with respect to the potential at the position of the radiator 66.

As a result, a weak current is generated in the coolant circulation line 67 through the coolant. Coolant circulation line 6
The generation of the current along 7 involves inconveniences such as causing power loss of the fuel cell 50 due to heat generation of the coolant circulation line 67.

Further, as described above, the cooling liquid circulation line 67 is not limited to the inside of the fuel cell storage case 68, but also penetrates the wall surface of the fuel cell storage case 68 and is exposed to the outside of the fuel cell storage case 68. The piping constituting the coolant circulation line 67 is electrically insulated from the coolant, but if a potential distribution occurs in the coolant, the coolant leaks to the outside for some reason, or In the case where dew condensation occurs on the connection flange 69 provided in the coolant circulation line 67, a weak current leaks outside the fuel cell storage case 68, and the ground level of the vehicle body on which the fuel cell 50 is mounted becomes lower. There may be inconveniences that fluctuate and adversely affect the operation of a control device or a sensor of the fuel cell that operates based on the ground level.

Conventionally, in order to suppress an increase in the conductivity of the coolant, an ion removal filter (not shown) is arranged at a position midway along the coolant circulation line 67 so that metal ions dissolved from a flow path in the radiator 66 are removed. Elimination has been done.

[0012]

However, since the ion removal performance of the ion removal filter decreases with use, in order to keep the conductivity of the coolant constantly low, the ion removal filter is frequently used. Must be replaced. Therefore, when the generation of the potential distribution along the coolant circulation line 67 is suppressed by the ion removal filter, there is a problem that the cost required for maintenance is increased.

The present invention has been made in view of the above-mentioned circumstances, and even if a liquid junction phenomenon of a fuel cell due to a coolant flowing through a circulation line occurs, a weak current of the fuel cell along the circulation line outside the case is generated. It is an object of the present invention to provide a fuel cell cooling device capable of sufficiently suppressing generation thereof.

[0014]

In order to achieve the above object, the present invention employs the following means. According to the first aspect of the present invention, there is provided a fuel cell storage case for storing at least a fuel cell, and a heat exchange means for radiating a coolant of the fuel cell outside the fuel cell storage case (for example,
The radiator 4) in the embodiment is connected to the fuel cell and the heat exchange means through the wall surface of the fuel cell storage case, and the coolant is circulated between the fuel cell and the heat exchange means. A coolant circulation line, and at least a pair of penetration portions (for example, the ring-shaped member 7 in the embodiment) through which the coolant circulation line penetrates the fuel cell storage case are provided as grounds for the control device of the fuel cell. The fuel cell cooling device is characterized by being connected to the fuel cell cooling device.

According to the cooling device of the present invention, the coolant circulated in the fuel cell is caused to flow along the coolant circulating line and cooled by the heat exchange means outside the fuel cell storage case. The fuel flows along the coolant circulation line and returns to the fuel cell inside the fuel cell storage case. Thereby, the fuel cell is cooled.

As the coolant is circulated along the coolant circulation line, the conductivity of the coolant is increased by metal ions dissolved from the fuel cell, heat exchange means and other metal parts, and both electrodes of the fuel cell are liquefied. And a potential distribution is generated along the coolant circulation line. That is, the potential decreases from the positive electrode of the fuel cell to the negative electrode of the fuel cell along the coolant circulation line.

In this case, according to the cooling device of the present invention, the coolant circulation line is connected to the ground of the control device of the fuel cell at a pair of penetration portions penetrating the fuel cell storage case. The potential on the outer surface of the coolant circulation line is once set to the ground potential in the penetrating portion of the fuel cell storage case. As a result, the generation of a weak current in the cooling liquid circulation line disposed outside the fuel cell storage case is suppressed, and the ground level of the control device disposed outside the fuel cell storage case is changed. Occurrence is also suppressed.

According to a second aspect of the present invention, in the fuel cell cooling device according to the first aspect, the pair of penetration portions are each electrically connected to the coolant flowing inside the coolant circulation line. A battery cooling device is proposed. According to the fuel cell cooling device of the present invention, the pair of through portions connected to the ground are electrically connected to the coolant, so that the coolant flowing through the coolant circulation line also communicates with each of the through portions. It will be connected to ground at the conduction position.

Therefore, in the section outside the fuel cell storage case sandwiched between the two penetration portions, the coolant in the cooling liquid circulation line is also set to the ground potential, and the cooling liquid disposed outside the fuel cell storage case is arranged. Generation of a current due to a liquid junction in the circulation line can be more reliably suppressed.

According to a third aspect of the present invention, in the fuel cell cooling device according to the first or second aspect, the pair of penetrating portions are electrically conductive through the fuel cell storage case. The device is proposed. According to the fuel cell cooling device according to the present invention, the pair of conductive penetrating portions and the fuel cell storage case are set to the same potential, which is generated in the coolant circulation line inside the fuel cell storage case. The potential distribution is shielded by the fuel cell storage case connected to the ground, so that the current generated inside the fuel cell storage case can be suppressed from leaking to the outside of the fuel cell storage case.

According to a fourth aspect of the present invention, in the fuel cell cooling device according to any one of the first to third aspects, the heat exchange means is electrically connected to a cooling liquid flowing inside the fuel cell cooling apparatus, and A fuel cell cooling device connected to the ground of a battery control device has been proposed. According to the fuel cell cooling device according to the present invention, the cooling liquid circulation line connected to the ground of the control device at the penetration portion of the fuel cell storage case is disposed at an intermediate position between the two penetration portions. Is connected to the ground, it is possible to more reliably prevent a potential distribution from being generated in the coolant circulation line outside the fuel cell storage case.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a fuel cell cooling device 1 according to the present embodiment is a radiator that cools a cooling liquid (for example, pure water) that flows through a fuel cell 3 in which a plurality of unit cells 2 are stacked. (Heat exchange means) 4, a radiator 4, and a coolant circulation line 5 for connecting the radiator 4 and the fuel cell 3 and circulating a coolant between them.
Is provided.

The fuel cell 3 is, for example,
Is stored in a fuel cell storage case 6 made of an insulating material such as a heat-resistant resin in order to keep the temperature and / or insulate it from the outside. In addition, the radiator 4
Are arranged outside the fuel cell storage case 6 for heat exchange with the outside air. Therefore, the coolant circulation line 5 penetrates the wall surface of the fuel cell storage case 6 at a position halfway between the fuel cell 3 and the radiator 4 and at a position halfway between the radiator 4 and the fuel cell 3. ing.

The coolant circulation line 5 is constituted by, for example, a pipe 8 made of a conductive metal material.
The pipe 8 is electrically insulated from the cooling liquid by a suitable means such as, for example, coating the inner surface with an electrically insulating paint or the like. Alternatively, the pipe 8 itself may be made of an electrically insulating material to be electrically insulated from the coolant.

In the fuel cell cooling device 1 according to the present embodiment, conductive base ring-shaped rings are used as two penetration portions through which the coolant circulation line 5 provided on the wall surface of the fuel cell storage case 6 penetrates. Form member 7 is arranged. These ring-shaped members 7 are electrically connected to a pipe 8 constituting the coolant circulation line 5, and are connected to a vehicle body (ground) on which the fuel cell 3 and its control device (not shown) are mounted. Have been. In the illustrated example, the radiator 4 is also connected to the vehicle body. In the drawing, reference numeral 9 denotes a pipe 8 outside the fuel cell storage case 6.
This is a connection flange for connecting.

According to the fuel cell cooling device 1 of the present embodiment configured as described above, a liquid junction phenomenon of the fuel cell 3 occurs, so that the cooling liquid is provided in the longitudinal direction of the cooling liquid circulation line 5. A potential distribution along it occurs. Further, since the coolant and the pipe 8 forming the coolant circulation line 5 are electrically insulated, it is possible to prevent the potential distribution generated in the coolant from causing the pipe 8 to generate a potential distribution.

Further, even if the coolant leaks to the outer surface of the pipe 8 constituting the coolant circulation line 5 for some reason, or if dew condensation occurs on the outer surface of the pipe 8 and the connection flange 9, the coolant circulation is performed. Since the line 5 is connected to the ground by the ring-shaped member 7 provided at the penetrating portion of the fuel cell storage case 6, it is possible to prevent a potential distribution from being generated in the pipe 8 exposed to the outside of the fuel cell storage case 6.

As a result, a current caused by a liquid junction is prevented from flowing through the coolant circulation line 5 outside the fuel cell storage case 6, and the occurrence of inconvenience such as a fluctuation in the ground level of the vehicle body is suppressed. . In particular, in the present embodiment, the radiator 4 provided at an intermediate position of the coolant circulation line 5 is also connected to the vehicle body. Therefore, the fuel cell housing connected to the ground at two places by the two ring-shaped members 7 is provided. The piping 8 outside the case 6 is also set to the ground potential at the radiator 4 at an intermediate position, and the generation of a potential distribution along the coolant circulation line 5 outside the fuel cell storage case 6 is more reliably suppressed. Will be.

Next, a fuel cell cooling device 10 according to a second embodiment of the present invention will be described below. The external configuration of the cooling device 10 according to the present embodiment is the same as that of the cooling device 1 according to the above-described first embodiment, except that the ring-shaped member 7 disposed in the penetration portion of the fuel cell storage case 6 This is different from the cooling device 1 according to the first embodiment in that it is electrically connected to the liquid.

In the present embodiment, for example, the piping 8 constituting the coolant circulation line 5 referred to in the first embodiment
When the electrically insulating paint on the inner surface is not applied at the position of the ring-shaped member 7 or a part of the pipe 8 made of the electrically insulating material is partially conductive at the position of the ring-shaped member 7. It is assumed that it is made of a material.

According to the fuel cell cooling device 10 of the present embodiment, the coolant circulation line 5 is connected to the fuel cell storage case 6.
Is connected to the ground, not only the pipes 8 constituting the coolant circulation line 5 but also the coolant flowing through the pipes 8 can be connected to the ring-shaped members 7. Is set to the ground potential at the position. FIG. 2 shows the relationship between the distance L along the coolant circulation line 5 with the positive electrode of the fuel cell as the origin and the potential Va of the coolant.
It becomes as follows.

That is, in the cooling device 10 of the present embodiment, the cooling liquid from the fuel cell 3 disposed inside the fuel cell storage case 6 to the position of the ring-shaped member 7 which is a penetrating portion of the fuel cell storage case. Although the potential changes, in the cooling circulation line 5 arranged outside the fuel cell storage case 6, the potential of the coolant is maintained at the ground potential. Also, at the position of the connection flange 9 of the pipe 8 arranged between them, the potential of the coolant is the potential of the ground. Therefore, no current flows along the coolant circulation line 5 outside the fuel cell storage case 6, and the occurrence of inconvenience due to the liquid junction of the fuel cell 3 is reliably prevented.

Next, a fuel cell cooling device 20 according to a third embodiment of the present invention will be described below with reference to FIG. In this embodiment, the same reference numerals are given to portions having the same configuration as those of the cooling devices 1 and 10 according to the first and second embodiments described above, and the description will be simplified.

In the cooling device 20 according to the present embodiment, the fuel cell storage case 21 for storing the fuel cell 3 is made of a conductive material, and is electrically connected to the ring-shaped member 7 forming the through portion. This is different from the cooling devices 1 and 10 according to the above-described first and second embodiments.

According to the cooling device 20 of the present embodiment configured as described above, the coolant circulation line 5 inside the fuel cell storage case 21 in which the potential distribution occurs in the coolant due to the liquid junction of the fuel cell 3, The fuel cell can be shielded by the fuel cell storage case 21 held at the ground potential. As a result, the weak current generated inside the fuel cell storage case 21 is prevented from leaking to the outside of the fuel cell storage case 21, and the fluctuation of the ground level of the vehicle body can be more reliably prevented.

In the above embodiments, the case where the radiator 4 is connected to the ground has been described.
When the radiator 4 is not made of a conductive material or the like, it is not necessary to connect to the ground. In this case, the middle position of the coolant circulation line 5 disposed outside the fuel cell storage cases 6 and 21 may be connected to the ground by another method.

In the above embodiments, pure water has been described as an example of the cooling liquid. However, the present invention may be applied to a case where an arbitrary cooling liquid such as ethylene glycol or oil is used instead. . Further, although the ring-shaped member 7 is employed as a penetrating portion in which the coolant circulation line 5 penetrates the fuel cell storage cases 6 and 21, the invention is not limited to this. , 21 as long as they can be connected to the ground at the entrances and exits.

[0038]

As is clear from the above description, the present invention has the following effects. (1) According to the fuel cell cooling device according to the first aspect of the present invention, the potential distribution generated along the coolant circulating line due to the liquid junction of the fuel cell causes the pair of penetration portions to penetrate the fuel cell storage case. By setting to the ground potential, it is possible to prevent a current from flowing to the coolant circulation line outside the fuel cell storage case due to a liquid junction. As a result, fluctuations in the ground level in the vehicle body on which the fuel cell is mounted are suppressed, and the control device and the sensor that operate based on the ground level can be operated properly.

(2) According to the fuel cell cooling device according to the second aspect of the present invention, the coolant penetrates the coolant through the through portion of the coolant circulation line connected to the ground, so that the coolant also flows through the ground at the through portion. Set to potential. As a result, the coolant in the coolant circulation line is also set to the ground potential in a section outside the fuel cell storage case sandwiched between the two penetration portions, and a current generated through the coolant is generated outside the fuel cell storage case. Can also be prevented.

(3) According to the fuel cell cooling device according to the third aspect of the invention, the pair of through portions and the fuel cell storage case are set to the same potential as the ground potential, and are disposed between the pair of through portions. Generation of a potential distribution in the cooling liquid circulation line outside the fuel cell storage case can be suppressed, and the cooling liquid circulation line inside the fuel cell storage case can also be shielded to prevent leakage current from the fuel cell storage case. Generation can also be prevented.

(4) According to the fuel cell cooling device according to the fourth aspect of the present invention, the cooling liquid is kept at the ground potential even in the heat exchange means arranged at a position midway in the cooling liquid circulation line outside the fuel cell storage case. By setting, it is possible to more reliably prevent the potential distribution from being generated in the circulation line in the section outside the fuel cell storage case.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fuel cell cooling device according to first and second embodiments of the present invention.

FIG. 2 is a diagram showing a potential distribution along a coolant circulation line of the cooling device of FIG. 1;

FIG. 3 is a schematic diagram showing a fuel cell cooling device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining the structure of a fuel cell.

FIG. 5 is a schematic view showing a conventional fuel cell cooling device.

6 is a diagram showing a potential distribution along a coolant circulation line of the cooling device of FIG. 5;

[Explanation of symbols]

 1, 10, 20 fuel cell cooling device 2 unit cell 3 fuel cell 4 radiator (heat exchange means) 5 coolant circulation line 6, 21 fuel cell storage case 7 ring-shaped member (penetrating part)

Claims (4)

[Claims] 1. A fuel cell storage case for storing at least a fuel cell, heat exchange means for radiating a coolant of the fuel cell outside the fuel cell storage case, and a fuel cell penetrating through a wall surface of the storage case. A coolant circulation line for circulating a fuel cell coolant between the fuel cell and the heat exchange means, wherein at least the coolant circulation line passes through the storage case. A pair of through-holes connected to a ground of a control device of the fuel cell. 2. The fuel cell cooling device according to claim 1, wherein each of the pair of through portions is electrically connected to a coolant flowing inside the circulation line. 3. The fuel cell system according to claim 1, wherein the pair of penetrating portions are electrically connected via the fuel cell storage case.
Or the fuel cell cooling device according to claim 2. 4. The apparatus according to claim 1, wherein the heat exchange means is electrically connected to a coolant flowing through the heat exchange means and is connected to the ground. Fuel cell cooling device.