JPH09139225A - Fastening device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening device for a fuel cell, capable of retaining necessary fastening pressure even in a condition where bellows pressure is lost, and eliminating the large size of the fuel cell even in a fuel cell having the many numbers of laminated layers. SOLUTION: A bellows 7 is provided, between an upper part base plate 5 installed in the upper part of a fuel cell 3 and a pushing plate 4 for pushing the fuel cell 3 to a lower part base plate 1, to supply pressure fluid to the bellows 7 from a pressure fluid supply device to generate fastening force for the fuel cell 3. A safety device can retain given fastening force when fastening force for the fuel cell 3 by the bellows 7 is lost. An interval retaining device can retain the interval, between the upper part base plate 5 and the pushing plate 4, at given interval.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening device for a stacked fuel cell, which is formed by alternately stacking a plurality of unit cells and separators.

[0002]

2. Description of the Related Art Generally, in a fuel cell, a matrix holding an electrolyte is sandwiched between a cathode and an anode electrode to form a unit cell, and a plurality of the unit cells are further stacked via a separator to form a stack. The battery is formed. Fuel gas is caused to flow on one side of the separator, and oxidant gas is caused to flow on the opposite side. That is, a combustible fuel gas containing hydrogen gas as the fuel gas is flown to the anode electrode side, and an oxidant gas containing oxygen is flown to the cathode side.

In this case, a gas is prevented from leaking by applying a load to the stacked stack in the stacking direction to maintain the contact pressure between the separator and the unit cell. Further, the electrical contact resistance of each member decreases as the surface pressure in the stacking direction increases, so that the output of the fuel cell can be increased by applying an excessive weight in the stacking direction.

On the other hand, in the fuel cell, each member tends to shrink with the lapse of operating time, the strength also decreases, and if the surface pressure in the stacking direction becomes too large, the shrinkage is promoted. Therefore, the surface pressure in the stacking direction needs to be constantly maintained at a uniform and appropriate value in terms of contributing to power generation.

Conventionally, a tightening device as shown in FIG. 5 has been used as a tightening device for tightening a stacked fuel cell from above and below to prevent gas leakage and to maintain electric contact resistance between unit cells. ing.

In FIG. 5, the stacked fuel cells 3 are sandwiched between the lower base plate 1 and the pressing plate 4 with the insulating material of the heat insulating material 2 interposed therebetween, and one or more sealed bellows 7 are provided above the pressing plate 4. Install. This bellows 7
The space between the upper base plate 5 and the pressing plate 4 on which is installed is held by a rod 6 vertically attached to the lower base plate 1, and the rod 6 is fixed to the upper base plate 5.

These bellows 7 are connected by a pressure transmission pipe 8 and supplied with a pressurized pressure fluid from a pressurized fluid inlet 9 to expand the can body. This tightens the fuel cell 3. According to this tightening device, the surface pressure in the stacking direction can be easily maintained at a constant value by adjusting the pressure of the pressure fluid, so that the tightening device is applied to many stacking fuel cell tightening devices.

[0008]

However, since the fuel cell tends to contract and become brittle during continuous operation, the fuel cell such as the bellows 7, the pressure transmission pipe 8, the pressure fluid supply device, etc. When the internal pressure of the can body (bellows) is lost due to corrosion or malfunction, the gas seal function may be deteriorated. For example, if the surface pressure in the stacking direction falls below the minimum required pressure value, the gas sealing function between the unit cells and the separator is lost, and fuel gas and oxidant gas leak. As a result, the fuel gas and the oxidant gas may directly burn or explode, which may lead to the destruction of the fuel cell.

Further, even if the pressure is temporarily lost, the brittle unit cell may be internally cracked due to a sudden change in surface pressure, and so-called cross in which the gas is directly mixed inside the fuel cell. It causes a leak, which causes an abnormal rise in temperature and a drop in performance, which may also lead to irreversible destruction of the fuel cell.

In principle, the fuel cell can generate only a voltage of about 0.8 V in a single cell, and the current that can be passed is (100 to 200 mm) A / cm 2, so that a high output can be obtained. Therefore, it is necessary to increase the electrode area and increase the number of unit cells to be stacked. When the number of stacked unit cells increases, the amount of shrinkage accompanying the operation of the fuel cell increases in proportion to the number of stacked units. Therefore, the operating distance of the bellows 7 also increases, so that if the bellows 7 have the same structure, the height of the bellows 7 increases in proportion to the number of stacked layers, and the tightening device becomes large.

As described above, the bellows type tightening device has an advantage that the tightening pressure can be easily controlled and the fuel cell can be uniformly tightened. However, when the bellows pressure is lost, a gas leak or a fuel cell failure occurs. There is a risk of destruction, and the device may increase in size.

An object of the present invention is to provide a tightening device for a fuel cell, which can maintain a necessary tightening pressure even when the bellows pressure is lost and does not become large even in a fuel cell having a large number of stacked layers. It is a thing.

[0013]

According to the invention of claim 1, there is provided a bellows provided between an upper base plate installed at an upper portion of the fuel cell and a pressing plate for pressing the fuel cell against the lower base plate, and a bellows. Pressure fluid supply device for supplying pressure fluid to generate the tightening force of the fuel cell, safety device for maintaining a predetermined tightening force when the bellows loses the tightening force of the fuel cell, upper base plate and pressing And a gap holding device for holding a gap between the plate and the plate at a predetermined gap.

According to the first aspect of the present invention, when the pressure of the pressure fluid supplied to the bellows is lost, the safety device holds a predetermined tightening force. Further, when the pressing plate moves to maintain the tightening force, the gap holding device holds the gap between the upper base plate and the pressing plate at a predetermined gap. As a result, the function of preventing gas leakage is maintained, electrical contact between the members of the fuel cell is maintained, and the tightening device can be downsized.

According to a second aspect of the present invention, in the first aspect of the present invention, the safety device includes a rod which is inserted between the upper base plate and the pressing plate and which rotates with the movement of the pressing plate, and is pressed by a bellows attached to the rod. A block with a stopper is provided which allows the rod to rotate in the direction of pressing against the plate and prevents the rod from rotating in the opposite direction to hold the tightening pressure of the fuel cell at the pressure of the normal operating state of the fuel cell.

According to the second aspect of the invention, the bellows expands in response to the contraction of the fuel cell to rotate the rod and move the block with stopper. The block with stopper holds the tightening pressure in that state as the tightening pressure in the normal operation state of the fuel cell. This maintains the pressure in the normal operating state even when the pressure of the pressure fluid supplied to the bellows is lost.

According to a third aspect of the present invention, in the space holding device according to the first aspect, the bellows expands due to contraction of the fuel cell, the pressing plate moves downward, and the distance between the upper base plate and the pressing plate is predetermined. When the value exceeds the upper limit of
The upper base plate is moved downward so that the distance between the upper base plate and the pressing plate becomes a predetermined distance.

According to the third aspect of the present invention, when the pressing plate moves downward due to the contraction of the fuel cell, the distance maintaining device moves the upper base plate downward so that the distance between the upper base plate and the pressing plate becomes a predetermined distance. Hold. As a result, the tightening device is downsized.

[0019]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing the first embodiment of the present invention. The first embodiment is provided with, as a safety device, a block 10a with a stopper, which is provided with a threaded portion on the rod 6 and engages with the threaded portion. This safety device maintains a predetermined tightening force when the tightening force of the fuel cell 3 by the bellows 7 is lost. Further, as a space maintaining device, a spring 12 provided on the spring rod 13 for pushing down the upper base plate 5 is used.
A nut 14 and a ring 15 for holding the spring 12, and a limiter block 11 that defines upper and lower limits of the distance between the upper base plate 5 and the pressing plate 4.
A block with a stopper 10b and a spring 12
Acts to push down the upper base plate 5, and when the pressing plate 4 moves downward due to contraction of the fuel cell 3 and reaches the upper limit defined by the limiter block, the upper base plate 5 is lowered downward to the lower limit defined by the limiter block. Push down. Then, at that time, the block with stopper 10b
Holds the position of the upper base plate 5. Thereby, the space between the upper base plate 5 and the pressing plate is maintained at a predetermined space.

In FIG. 1, the same elements as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. Similar to the conventional example shown in FIG. 5, the stacked fuel cells 3 have the base plate 1 and the pressing plate 4 with the insulating material of the heat insulating material 2 interposed therebetween.
It is sandwiched between and placed. A single or a plurality of sealed bellows 7 are provided on the top of the pressing plate 4. A rod 6 vertically attached to the lower base plate 1 is fixed to the upper base plate 5. Therefore, the bellows 7 is installed between the upper base plate 5 and the pressing plate 4.

The bellows 7 are connected by a pressure transmission pipe 8, and a pressurized fluid is supplied from a pressurized fluid inlet 9 to expand the can body (bellows). This tightens the fuel cell 3. Further, a block 10a with a stopper is fixedly installed on the pressing plate 4 through the threaded portion of the rod 6. The block 10a with a stopper is provided with a limiter block 11 that defines the upper limit and the lower limit of the distance between the upper base plate 5 and the pressing plate 4. Similarly, a block 10b with a stopper is fixed to the upper base plate 5 by penetrating the threaded portion of the rod 6.

Next, the spring rod 13 is arranged such that one end thereof is joined to the pressing plate 4, and the spring rod 13 is
Penetrates a hole formed in the upper base plate 5, and the spring 12 is inserted into the spring rod 13 there. The spring 12 is held by the ring 15 and the nut 14 so as to be sandwiched between the spring 12 and the base plate 5. Here, the spring 2 is tightened by the nut 14 by a required amount, and the spring reaction force is always applied, so that the upper base plate 5 is pressed against the pressing plate 4.

FIG. 2 is a detailed view of the block 10 with stopper. As shown in FIG. 2, the block with stopper 10
A shaft 16 with a gear is fixed in the inside of so as to mesh with the threaded portion of the rod 6, and rotates with the movement of the pressing plate 4 or the upper base plate 5. This geared shaft 1
A stopper 17 is attached to the gear No. 6 as shown in FIG. 2, and rotation in the direction of the arrow shown in the gear portion in FIG. 2 is allowed. It is configured to mesh with gears and prevent rotation. As a result, the block with stopper 10a prevents the pressing plate 4 from moving upward, and the block with stopper 10
b prevents the upper base plate 5 from moving upward.

Next, FIG. 3 shows a detailed view of the limiter block 11. As shown in FIG. 3, a terminal bar 19 that is constantly pushed up by a spring 18 is provided inside the stopper-equipped block 10 installed on the pressing plate 4.
The terminal bar 19 is in contact with the upper base plate 5, and the terminal bar 19 has the bar 2 at the position shown in FIG.
0 is installed and the bar 20 moves up and down as the upper base plate 5 moves. When the bar 20 reaches the upper limit, that is, the upper limit, the upper limit micro switch 21
Works. Similarly, the lower limit microswitch 22 operates when the bar 20 reaches the lower limit, or lower limit.

Here, when the upper limit microswitch 21 operates, the pressure of the pressurized fluid supplied to the bellows 7 is eliminated, and when the lower limit microswitch 22 acts, the pressure of the pressurized fluid recovers. Signal is sent to the pressurized fluid supply device via the lead wire 23.

Now, consider a case where the fuel cell 3 contracts and the bellows 7 expands due to the internal pressure to tighten the fuel cell 3. In that case, the block with stopper 10a
As a result, the pressing plate 4 can move in the contracting direction of the fuel cell 3, but cannot move in the expanding direction.
Further, due to the reaction force of the elastic deformation of the fuel cell 3, the pressing plate 4
Are not pushed back in the direction of expansion of the fuel cell 3. Therefore, since the pressing plate 4 is restrained at the position at that time, the reaction force acts on the fuel cell 3 itself and the tightening pressure is maintained.

On the other hand, when the pressing plate 4 moves downward due to contraction accompanying the operation of the fuel cell 3, a gap is created between the limiter block 11 and the upper base plate 5. When the fuel cell further contracts, the limiter block 11 is finally released.
The upper limit micro switch 21 operates to automatically release the fluid pressure of the bellows 7. Then, since the reaction force of the bellows 7 is lost, the upper base plate 5 is pushed down by the spring 12, the gap between the upper base plate 5 and the limiter block 11 becomes small again, and the terminal bar 19 is pushed down. Further, when the interval becomes smaller, the lower limit micro switch 22 operates and pressure is applied to the bellows 7 again. As long as the fuel cell 3 continues to contract, this series of operations is repeated, so that the upper base plate 5 constantly repeats movement in accordance with the contraction of the fuel cell 3 so as to keep the distance from the pressing plate 4 substantially constant.

As described above, according to the first embodiment, the required tightening pressure is constantly maintained and the distance between the upper base plate 5 and the pressing plate 4 is kept substantially constant by the extremely simple mechanism. Therefore, the required operating distance of the bellows 7 may be designed to be the distance between the upper and lower limit microswitches. This makes it possible to provide a very compact tightening device.

Next, FIG. 4 shows a second embodiment of the present invention. In the second embodiment, the upper base plate 5 is pressed downward by a servo motor 26 in place of the spring 12 of the spacing device in the first embodiment. That is, the spring 12,
Instead of the spring rod 13, the nut 14, and the ring 15, a nut with gear 24 for supplying a pressing force to the upper base plate 5, a worm gear 25 for transmitting a torque to the nut 24 with a gear, and a worm gear 25 with torque. The servo motor 26 is given.

In FIG. 4, the same elements as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The stacked fuel cells 3 are sandwiched by the base plate 1 and the pressing plate 4 with the insulating material of the heat insulating material 2 interposed therebetween. A sealed bellows 7 is provided on the top of the pressing plate 4. The upper base plate 5 is fixed to the rod 6 vertically attached to the lower base plate 1,
The bellows 7 is arranged between the pressing plate 4 and the upper base plate 5.

The bellows 7 are connected by a pressure transmission pipe 8, and a pressurized fluid is supplied from a pressurized fluid inlet 9 to expand the can body (bellows) to tighten the fuel cell 3. Further, the block with a stopper 10a is fixedly installed on the pressing plate 4 by penetrating the threaded portion of the rod 6. Similarly, a block 10b with a stopper is fixed to the upper base plate 5 as well by penetrating the threaded portion of the rod 6.

A limiter block 11 is attached to the pressing plate 4. On the upper part of the block with stopper 10b attached to the upper base plate 5,
A nut 24 with a gear attached to the rod 6 is installed, and the nut 24 with a gear is a worm gear 25.
It is configured to be rotated by the servo motor 26 via.

Inside the limiter block 11, a terminal bar 19 which is constantly pushed up by a spring 18 is in contact with the upper base plate 5 as shown in FIG. This terminal bar 19 has a bar 2 at a position as shown in FIG.
0 is installed and the bar 20 moves up and down as the upper base plate 5 moves. An upper limit micro switch 21 that operates when the bar 20 reaches the upper limit,
A lower limit microswitch 22 is fixed which operates when the bar 20 reaches the lower limit. Although not shown in FIG. 3, when the upper limit microswitch 21 operates, the servomotor 26 rotates so that the nut 22 lowers, and when the lower limit microswitch 22 acts, the rotation of the servomotor 26 is prevented. Configure to stop.

With this configuration, as long as the fuel cell 3 continues to contract, this series of operations is repeated, so that the upper base plate 5 keeps the space between the upper base plate 5 and the pressing plate 4 almost constant. It is obvious that the same effect as that of the first embodiment can be obtained because it has the action of always returning according to the contraction of 3.

[0035]

As described above, according to the present invention, when the position of the pressing plate where the bellows directly presses the fuel cell contracts as the operating time of the fuel cell elapses, the pressing plate responds to the contraction. Moves, the position of the pressing plate is restrained from moving in the direction opposite to the contracting direction to hold the position of the pressing plate, and when the pressing plate moves downward by a certain distance due to contraction of the fuel cell, Since the upper base plate is pushed down to a predetermined distance, the pressing plate is restrained at the position at that time without returning to the reverse direction of the load direction (the expansion direction of the fuel cell).

Therefore, the reaction force generated by the elastic deformation of the fuel cell corresponding to the surface pressure during normal operation acts on the fuel cell itself and the tightening pressure is maintained. Therefore, the gas sealing function between the unit cell and the separator is maintained, and the rapid expansion of the fuel cell is avoided. Further, since the structure of the bellows may have a minimum required working distance, a compact tightening device that does not depend on the number of stacked fuel cells can be provided.

As described above, the present invention has a simple mechanism,
It is possible to maintain the gas sealing function of the fuel cell while maintaining the required tightening pressure. In addition to preventing damage due to sudden expansion of the fuel cell to prevent unrecoverable deterioration of performance of the fuel cell, the operating distance of the bellows can be minimized regardless of the number of stacked fuel cells. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a block with a stopper according to the present invention.

FIG. 3 is an explanatory diagram of a limiter block according to the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional example.

[Explanation of symbols]

 1 Lower Base Plate 2 Heat Insulation Material 3 Fuel Cell 4 Pressing Plate 5 Upper Base Plate 6 Rod 7 Bellows 8 Pressure Transmission Pipe 9 Pressurized Fluid Inlet 10 Block with Stopper 11 Limiter Block 12 Spring 13 Spring Rod 14 Nut 15 Ring 16 Geared Shaft 17 Stopper 18 Spring 19 Terminal Bar 20 Bar 21 Upper Micro Switch 22 Lower Micro Switch 23 Lead Wire 24 Nut with Gear 25 Worm Gear 26 Servo Motor

Claims (3)

[Claims] 1. A fuel cell formed by alternately stacking a plurality of unit cells and separators is clamped from above and below to prevent leakage of a fuel gas and an oxidant gas supplied to the unit cells, and between the unit cells. In a tightening device of a fuel cell for maintaining the electrical contact of, a bellows provided between an upper base plate installed on the upper part of the fuel cell and a pressing plate for pressing the fuel cell to the lower base plate, A pressure fluid supply device for supplying a pressure fluid to the bellows to generate a tightening force of the fuel cell, and a safety device for maintaining a predetermined tightening force when the bellows loses the tightening force of the fuel cell. And a gap holding device for holding the gap between the upper base plate and the pressing plate at a predetermined gap. Batteries tightening device. 2. The safety device includes a rod which is inserted between the upper base plate and the pressing plate and which rotates as the pressing plate moves, and a pressing direction of the bellows attached to the rod to the pressing plate. In contrast to the above, a block with a stopper is provided, which enables rotation of the rod and prevents rotation in the opposite direction to hold the tightening pressure of the fuel cell at the pressure of the normal operating state of the fuel cell. The tightening device for a fuel cell according to claim 1. 3. In the gap holding device, the bellows expands due to contraction of the fuel cell, the pressing plate moves downward, and the gap between the upper base plate and the pressing plate becomes larger than a predetermined upper limit value. The fastening device for a fuel cell according to claim 1, wherein the upper base plate and the pressing plate are moved downward so that the distance between the upper base plate and the pressing plate is a predetermined distance.