JP2003178791A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system which can discharge not only condensed water and formed water during the operation, but also condensed water present before starting, to prevent clogging with water. <P>SOLUTION: Water pool portions 10 for temporarily storing condensed water or formed water condensed or formed in a fuel gas feeding pipe 4, a fuel gas discharging pipe 5, an air feeding pipe 6 or an air exhaust pipe 7, or from a fuel cell stack 1 are provided at respective connection parts of these pipes to an end plate 3. A drain pipe 12 is connected to each water pool portion 10 through an electromagnetic valve 11 that is a drain valve opening and closing according to electric signals to drain water stored in the water pool portion 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system that produces water by an electrochemical reaction and has improved drainage performance.

[0002]

2. Description of the Related Art When excessive water is present in a gas passage in a fuel cell (hereinafter referred to as water clogging), the gas supply becomes a resistance and the power generation efficiency of the fuel cell decreases.

In order to prevent this, for example, Japanese Patent Laid-Open No. 11-1
In Japanese Patent No. 62489, a heat exchanger capable of exchanging heat between a fuel gas and cooling water that cools and circulates a fuel cell is installed, and a flow of cooling water at the time of startup is switched to the heat exchanger. Before supplying the humidified and heated fuel gas to the fuel cell, it exchanges heat with the cooling water, which is the temperature of the fuel cell that is still cold, to lower the temperature, condense excess water vapor, and The method of preventing it from condensing in is taken.

[0004]

However, in this conventional example, only the vapor contained in the fuel cell is prevented from condensing at the time of start-up, and the vapor remaining in the fuel cell at the time of the operation stop before that is caused by the fuel cell. It also has a preventive effect against condensation that occurs as the temperature decreases, or water vapor that remains in the fuel cell inlet / outlet piping section also condenses and flows into the fuel cell at startup, resulting in water clogging. Since it does not exist, water clogging occurs due to condensed water that exists from the beginning at startup, causing a sudden drop in cell voltage,
There is a problem in that the desired output cannot be obtained, and in the worst case, the system must be stopped in order to protect the fuel cell from a drop in cell voltage.

In view of the above problems, an object of the present invention is to allow not only condensed water and generated water during operation but also condensed water existing before start-up to be discharged to prevent water clogging. Is to provide.

[0006]

In order to achieve the above object, the invention according to claim 1 is to provide a fuel cell main body for generating power by an electrochemical reaction of a fuel gas and an oxidant gas, and a fuel gas for the fuel cell main body. In a fuel cell system including a fuel gas supply means for supplying and an oxidant gas supply means for supplying an oxidant gas to the fuel cell body, at least one of a fuel gas passage and an oxidant gas passage of the fuel cell body. In the gas passage, a water pool for temporarily storing water, water guiding means for guiding the water in the gas passage to the water pool, and a drain valve for draining the water in the water pool are provided. And

In order to achieve the above object, the invention according to claim 2 is the fuel cell system according to claim 1, wherein the opening degree of the drainage valve, the valve opening time, The gist is to adjust at least one of the valve opening intervals.

To achieve the above object, the invention according to claim 3 is the fuel cell system according to claim 1, wherein the electric power taken out from the fuel cell main body is below a predetermined value according to the amount of water in the gas passage. The point is to limit to.

In order to achieve the above object, the invention according to claim 4 is the fuel cell system according to claim 1, wherein at least the fuel gas and the oxidant gas are contained in accordance with the amount of water in the gas passage. The point is to adjust one gas flow rate.

In order to achieve the above object, the invention according to claim 5 is the fuel cell system according to any one of claims 2 to 4, wherein pressure detecting means for detecting pressure is provided downstream of the drain valve. The gist of the present invention is to estimate the amount of water in the gas passage based on the pressure fluctuation when the drain valve is opened, which is detected by the pressure detecting means.

To achieve the above object, the invention according to claim 6 provides the fuel cell system according to claim 5, wherein a tank is provided downstream of the drain valve, and the pressure detecting means detects the pressure in the tank. The point is to do.

In order to achieve the above object, the invention according to claim 7 is the fuel cell system according to any one of claims 1 to 6, wherein the drainage is carried out at the time of start-up before the electric power is taken out from the fuel cell main body. The gist is to open the valve and drain the water in the water pool.

To achieve the above object, the invention according to claim 8 is the fuel cell system according to any one of claims 1 to 7, wherein the fuel cell main body comprises a stack in which a plurality of cells are laminated. The gas passage includes a manifold penetrating each cell, a gas flow channel formed on each cell inner electrode surface, and a connection hole that connects the manifold and the gas flow channel formed on each cell electrode surface. The gist of the water guiding means is that the water guiding means is inclined toward the water pool provided on the lower surface of the manifold.

In order to achieve the above object, a ninth aspect of the present invention provides a fuel cell system according to the eighth aspect, in which a lower surface of the manifold is lower than a lower end portion of the connection hole.

To achieve the above object, the invention according to claim 10 is characterized in that, in the fuel cell system according to claim 9, the lower end portion of the connection hole is provided with an inclination decreasing toward the manifold. To do.

To achieve the above object, the invention according to claim 11 is the fuel cell system according to any one of claims 1 to 10, wherein the water pool portion contains the fuel gas or the oxidant gas. The gist is that the gas pipe is provided in the vicinity of the connecting portion to the fuel cell body.

[0017]

According to the invention of claim 1, a fuel cell main body for generating power by an electrochemical reaction of a fuel gas and an oxidant gas, and a fuel gas supply means for supplying the fuel gas to the fuel cell main body. In a fuel cell system including an oxidant gas supply means for supplying an oxidant gas to the fuel cell main body, water is temporarily supplied to at least one of a fuel gas passage and an oxidant gas passage of the fuel cell main body. By providing a water pool for storing, water guiding means for guiding the water in the gas passage to the water pool, and a drain valve for draining the water in the water pool, the water vapor remaining at the time of the previous stop Condensed water that has condensed and accumulated in the gas passage, as well as condensed water during operation and generated water can be guided to the water pool by the water guiding means and drained from the drain valve. To prevent water clogging of the scan path, thereby facilitating the starting of the fuel cell, there is an effect that stable operation of the cell voltage becomes possible.

According to a second aspect of the present invention, in the fuel cell system according to the first aspect, depending on the amount of water in the gas passage, the opening degree of the drainage valve, the valve opening time, and the valve opening interval are set. Since at least one is adjusted, in addition to the effect of the invention described in claim 1, there is an effect that unnecessary valve opening is suppressed and effective drainage can be performed.

According to the invention described in claim 3, in the fuel cell system according to claim 1, the electric power taken out from the fuel cell main body is limited to a predetermined value or less in accordance with the amount of water in the gas passage. Therefore, in addition to the effect of the invention according to claim 1, in addition to the effect of the invention of claim 1, until the discharge of the condensed water is completed, the power extraction is limited to a predetermined value or less, the increase of the generated water is suppressed, or the power is unreasonably taken out when the power generation efficiency decreases Therefore, there is an effect that it is possible to prevent the fuel cell from being damaged.

According to the invention described in claim 4, in the fuel cell system according to claim 1, the gas flow rate of at least one of the fuel gas and the oxidant gas is changed according to the amount of water in the gas passage. Therefore, in addition to the effect of the invention described in claim 1, when the amount of water is large, it is possible to increase the gas flow rate and blow off the water.

According to the invention of claim 5, in the fuel cell system according to any one of claims 2 to 4, pressure detecting means for detecting pressure is provided downstream of the drain valve, and the pressure is detected. Since the amount of water in the gas passage is estimated based on the pressure fluctuation when the drainage valve is opened, which is detected by the detection means, in addition to the effects of the invention according to claims 2 to 4, Instead of providing water quantity detection means in each water pool, the pressure detection means commonly provided downstream of each drain valve changes the pressure downstream of the drain valve according to the amount of water discharged. The effect is that the amount of can be estimated.

According to the invention of claim 6, in the fuel cell system according to claim 5, a tank is provided downstream of the drain valve, and the pressure detecting means detects the pressure in the tank. Therefore, in addition to the effect of the invention as set forth in claim 5, there is an effect that the pressure downstream of the drain valve can be easily detected and the amount of water can be easily estimated.

According to a seventh aspect of the invention, in the fuel cell system according to any one of the first to sixth aspects, the drain valve is opened before power is taken out from the fuel cell main body at startup. Since the water in the water pool is drained, in addition to the effects of the invention according to claims 1 to 6, the water condensed in the fuel cell main body or the gas pipe connected to the main body is discharged in advance. Therefore, it is possible to take out a desired output in a shorter time after starting.

According to an eighth aspect of the present invention, in the fuel cell system according to any one of the first to seventh aspects, the fuel cell main body includes a stack in which a plurality of cells are laminated, and the gas passage is provided. Includes a manifold penetrating each cell, a gas flow channel formed on each cell inner electrode surface, and a connection hole that connects the manifold and the gas flow channel formed on each cell inner electrode surface, Since the means is inclined so as to decrease toward the water pool portion provided on the lower surface of the manifold, in addition to the effects of the invention according to claims 1 to 7, energy is consumed for water induction with a simple configuration. There is an effect that water can be automatically guided to the water pool by gravity.

According to the invention of claim 9, in the fuel cell system according to claim 8, the lower surface of the manifold is lower than the lower end portion of the connection hole. In addition, the water in the manifold is unlikely to enter the electrode surface, and the water on the electrode surface is easily discharged to the manifold, so that the water clogging prevention performance can be improved.

According to the invention of claim 10, claim 9 is provided.
In the fuel cell system described above, by providing an inclination that decreases toward the manifold at the lower end of the connection hole, it is possible to further improve the water clogging prevention performance.

According to the invention of claim 11, claim 1
In the fuel cell system according to any one of claims 1 to 10, in the stack, the water pool portion is provided in the vicinity of a connection portion of a gas pipe of the fuel gas or the oxidant gas to the fuel cell body. Since it is not necessary to carry the condensed water and the generated water of a long distance, there is an effect that the water discharge time is shortened.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a perspective view of a fuel cell stack 1 for explaining a first embodiment of a fuel cell system according to the present invention.

In FIG. 1, a fuel cell stack 1 which is a fuel cell main body for generating electricity by an electrochemical reaction of a fuel gas and an oxidant gas is a solid polymer electrolyte membrane and an anode (fuel electrode) to which the fuel gas is supplied. And a plurality of fuel battery cells (hereinafter, simply referred to as cells) 2 each including a cathode (oxidant electrode) to which an oxidant gas is supplied are stacked.

The plurality of cells 2 are fixed by sandwiching both ends between two end plates 3 (only one end is shown in FIG. 1). Further, to the end plate 3, a fuel gas supply pipe 4 for supplying a fuel gas 4, a fuel gas exhaust pipe 5 for exhausting the fuel gas 5, an air supply pipe 6 for supplying air as an oxidant gas 6, an air for exhausting air An exhaust pipe 7, a coolant supply pipe 8 for supplying a coolant, and a coolant discharge pipe 9 for discharging the coolant are connected to each other.

The fuel gas supply pipe 4, the fuel gas exhaust pipe 5, the air supply pipe 6, and the air exhaust pipe 7 are connected to the respective end plates 3 in the pipes or from the fuel cell stack 1. A water pool portion 10 for temporarily storing condensed water to be condensed or generated and generated water is provided,
A drain pipe 12 is connected to the water reservoir 10 via a solenoid valve 11 which is a drain valve that opens and closes in response to an electric signal, so that water accumulated in the water reservoir 10 can be drained.

Then, the fuel gas is supplied to the fuel gas supply pipe 4 from the fuel gas supply means (not shown), and the air is supplied to the air supply pipe 6 from the compressor as the oxidant gas supply means (not shown). As the fuel gas supply means, for example, a means for supplying hydrogen gas from a fuel tank such as a high pressure hydrogen tank via a pressure reducer can be considered.

In such a fuel cell system,
If the polymer membrane is not in a sufficiently wet state, it cannot function as a proton exchange membrane, so some kind of humidification method is applied to the membrane. The most general method among them is to supply sufficient fuel vapor only to the fuel gas or to both the fuel gas and the air by a humidifying means (not shown) before supplying the fuel gas to the fuel cell. As a result, the polymer membrane is supplied with sufficient water and exhibits a function as a proton exchange membrane.

FIG. 2 is a view showing an example of each flow path of the anode (a) and the cathode (b) of the bipolar plate used in the fuel cell 2 of the present invention.

In the anode flow channel shown in FIG. 2A, a thin fuel gas flow channel is formed on the electrode surface 21 by two interdigitated partition walls. Fuel gas is supplied from an internal manifold 20a penetrating the stacked cells 2 via an electrode surface inlet (connection hole) 21a, and discharged to an internal manifold 20c via an electrode surface outlet (connection hole) 21b. It is like this.

Further, the internal manifolds 20a and 20c for supplying and discharging gas are formed vertically long, and the connection holes 21a and 21b which are the entrances and exits to the electrode surface are connected only to the upper portions of the internal manifolds 20a and 20c, respectively. The lower surface of the internal manifold is lower than the lower end of the connection hole.

The lower surface of the connection holes 21a and 21b are
Since there is an inclination A from the electrode surface entrance / exit toward the internal manifolds 20a and 20c, the internal manifold 20
The water condensed in a and 20c is hard to flow into the electrode surface 21, and the water condensed in the electrode surface 21 is the internal manifold 2
It is easily discharged to 0a and 20c.

Similarly, in the cathode channel of FIG. 2B, a thin air channel is formed on the electrode surface 22 by two interdigitated partition walls. Stacked cells 2
Air is supplied from an internal manifold 20b penetrating through the internal manifold 20b through an electrode surface inlet (connection hole) 22a, and is discharged to the internal manifold 20d through an electrode surface outlet (connection hole) 22b.

Further, the internal manifolds 20b and 20d for supplying and discharging the gas are formed vertically long, and the connection holes 22a and 22b which are the entrances and exits to the electrode surface are connected only to the upper portions of the internal manifolds 20b and 20d, respectively. The lower surface of the internal manifold is lower than the lower end of the connection hole.

Further, the lower surfaces of the connection holes 22a and 22b are
Since there is an inclination A from the electrode surface entrance / exit toward the internal manifolds 20b and 20d, the internal manifold 20
The water condensed in b and 20d does not easily flow into the electrode surface 22, and the water condensed in the electrode surface 22 does not flow into the internal manifold 2
It is easily discharged to 0b and 20d.

FIG. 3 is a sectional view of the gas pipe and the internal manifold. As shown in FIG. 3, in the internal manifold 20 of each cell 2, the hole diameter is gradually increased toward the gas inlet to incline the lower surface of the internal manifold 20. As a result, the condensed water / produced water flows smoothly into the water pool portion 10 installed at the lowest position in the vicinity of the fuel cell stack 1 at the end plate 3 attachment portion of each gas pipe 4, 5, 6, 7. Has become. Further, a solenoid valve 11 is installed below the water pool 10, and its operation causes the water in the water pool 10 to be discharged through a drain pipe 12.

FIG. 4 is a system configuration diagram showing the configuration of the control system in the embodiment of the fuel cell system according to the present invention. In FIG. 4, each drain pipe 12 a, 12 b, 1 is provided downstream of the solenoid valve 11 installed below the water pool 10.
2c and 12d are respectively connected to an air system and a fuel gas system to form an air system drain pipe 12e and a fuel gas system drain pipe 12f.
, And are connected to the air side water tank 13 and the fuel gas side water tank 14, respectively.

The inside of these water tanks 13 and 14 is at atmospheric pressure when the solenoid valve 11 is closed by the pipe connected further downstream, and the pressure inside the tank is controlled by the pressure sensor 15 in the space where the gas is accumulated. It is designed to detect. The pressure detected by the pressure sensor 15 is input to the control device 16, and the operating condition at startup is determined according to the pressure.

Here, the water accumulated in the air side water tank 13 can be recovered and reused as humidifying water or the like.

FIG. 5 is a time chart showing the relationship between the water discharge amount and the water tank internal pressure. When the amount of water discharged by periodically opening the electromagnetic valve 11 that is a drain valve is large, the amount of water that flows in is relatively small with respect to the volume in the tank, so the pressure inside the water tank changes greatly. It doesn't happen. When the excess water is discharged, the ratio of fuel gas and air flowing in when the solenoid valve 11 is opened increases.
The pressure change becomes large. This makes it possible to determine whether or not the drainage of the condensed water at the time of startup is completed.

FIG. 6 is a time chart showing the relationship between the water tank internal pressure and the solenoid valve opening period, which is the period for opening the solenoid valve 11.

When the internal pressure of the air side water tank 13 or the fuel gas side water tank 14 is less than Pl, the control device 16 shown in FIG.
Is opened and closed with the shortest cycle Tmin, and the output of the fuel cell stack 1 is limited to a predetermined value Lp or less.
When the internal pressure of the water tank becomes equal to or higher than Pl, the opening cycle T of the solenoid valve 11 is sequentially lengthened to Ta, Tb, ... In accordance with the internal pressure value, and the output limit of the fuel cell stack 1 is set to L.
Relax it to p2 (Lp2> Lp) or less. When the internal pressure of the water tank exceeds Ph, it is judged that the discharge of the excess condensed water has ended, and the opening cycle of the solenoid valve 11 is set to the maximum value Tmax.

FIG. 8 is a diagram showing a control flow chart of the solenoid valve open cycle control. First, in step S10, in order to start the fuel cell, the power source of the battery or the like is turned on and the power supply to the control device is started. Then
In step S12, the operation of the electromagnetic valve 11 for drainage is started with the open cycle T set to the shortest cycle, and drainage of the condensed water condensed inside the fuel cell after the previous stop is started. Step S
At 14, the supply of fuel gas and air to the fuel cell stack is started, and the circulation of the coolant is started. Next, in step S16, the output extraction from the fuel cell stack is started, and in step S18, it is determined whether or not the normal operation of the fuel cell is possible based on the temperature of the fuel cell main body, the gas supply pressure, and the like. Move to normal operation control. If normal operation is not possible, in step S20, the pressure sensor 1
It is determined whether the internal pressure P of the water tanks 13 and 14 detected by 5 is lower than the pressure set value Pl. Internal pressure P is pressure set value P
If it is lower than l, in step S22, the output of the fuel cell stack is limited to the output limit value Lp [kW] or less, and the open period T of the drainage solenoid valve 11 is set to the shortest period, and the step S is performed.
Return to 18.

If it is determined in step S20 that the internal pressure P is equal to or higher than the pressure setting value Pl, it is determined in step S24 whether the internal pressure P is lower than the pressure setting value Ph. If the internal pressure P is lower than the pressure set value Ph, in step S26, the output of the fuel cell stack is limited to the output limit value Lp2 [kW] or less, and the opening cycle T of the electromagnetic valve 11 for drainage is set using the internal pressure P.
As a cycle of T = P × a + b (a and b are appropriate constants),
Return to step S18. If it is determined in step S24 that the internal pressure P is equal to or higher than the pressure set value Ph, in step S28,
The output limitation from the fuel cell stack due to the internal pressure P is eliminated, and the open cycle T of the drainage solenoid valve 11 is set to the longest cycle.
Return to step S18.

The pressure set values Pl and Ph for judging the internal pressures of the air side water tank 13 and the fuel gas side water tank 14 are set.
Usually do not match and often differ depending on the design value of the hydrogen gas concentration in the fuel gas, the shape of the gas passage, the shape of the drain pipe, the capacity of the water tank, and the like. In this case, the detection value of the pressure sensor 15 for each individual water tank is compared with the set Pl and Ph, and the drainage solenoid valve 11 provided in the air pipe and the fuel gas system The electromagnetic valve 11 for drainage provided in the pipe is controlled for each system.

Further, in the above flow chart, the opening cycle T of the solenoid valve is changed, but similarly the opening of the valve is changed (shortening the cycle = increasing the opening, increasing the cycle = opening). Alternatively, the valve opening time may be changed (shortening the cycle = increasing the opening degree, lengthening the cycle = decreasing the opening degree).

Further, by opening all the drainage solenoid valves 11 at the time of start-up and performing a condensed water discharge mode in which gas is supplied without taking out the output from the fuel cell stack, the discharge of condensed water is further promoted, and the condensed water is discharged more quickly. In addition, it is possible to take out a desired output from the fuel cell stack.

A control flow chart at this time is shown in FIG. First, in step S30, in order to start the fuel cell, the power source of the battery or the like is turned on and the power supply to the control device is started. Next, in step S32, all the electromagnetic valves 11 for drainage are held in the open state, and the condensed water condensed inside the fuel cell after the last stop is drained. In step S34, the supply of a predetermined amount of fuel gas and air to the fuel cell stack is started, the circulation of the coolant is started, and this state is maintained for a predetermined time. Then, step S
When a predetermined time elapses in 34, the open cycle T of the electromagnetic valve 11 for drainage is set to the shortest cycle in step S36. In step S38, the flow rates of the fuel gas and the air supplied to the fuel cell stack are set to the startup flow rates, and the output extraction from the fuel cell stack is suspended.

Then, in step S40, output extraction from the fuel cell stack is started, and in step S42, it is judged whether or not the normal operation of the fuel cell is possible based on the temperature of the fuel cell main body, the gas supply pressure, and the like. If so, shift to control of normal operation. If normal operation is not possible, step S44
Then, it is determined whether the internal pressure P of the water tanks 13 and 14 detected by the pressure sensor 15 is lower than the pressure set value Pl. If the internal pressure P is lower than the pressure set value Pl, in step S46,
The output of the fuel cell stack is limited to the output limit value Lp [kW] or less, and the open period T of the electromagnetic valve 11 for drainage is set as the shortest period, and the process returns to step S42.

If it is determined in step S44 that the internal pressure P is not less than the pressure setting value Pl, it is determined in step S48 whether the internal pressure P is lower than the pressure setting value Ph. If the internal pressure P is lower than the pressure set value Ph, in step S50, the output of the fuel cell stack is limited to the output limit value Lp2 [kW] or less, and the opening cycle T of the drainage solenoid valve 11 is set to the internal pressure P.
As a cycle of T = P × a + b (a and b are appropriate constants),
Return to step S42. If it is determined in step S48 that the internal pressure P is equal to or higher than the pressure set value Ph, in step S52,
The output limitation from the fuel cell stack due to the internal pressure P is eliminated, and the open cycle T of the drainage solenoid valve 11 is set to the longest cycle.
Return to step S42.

FIG. 7 shows a solenoid valve 1 for drainage even during normal operation.
The operation example in the case of suppressing water clogging by using No. 1 is shown. The operation of the solenoid valve 11 is almost the same as that at the start-up, but the difference is that it enters the water clogging elimination operation mode. In the water clogging elimination operation mode, the flow rate of fuel gas and air is increased to reduce the gas utilization rate, whereby the water can be blown away to eliminate the water clogging.

A flow chart at this time is shown in FIG. First, in step S60, it is determined whether or not the operation is stopped from the normal operation state. If the operation is stopped, the operation is ended. If the operation is not stopped, it is determined in step S62 whether the internal pressure P of the water tanks 13 and 14 detected by the pressure sensor 15 is lower than the pressure set value Pl. If the internal pressure P is lower than the pressure set value Pl, the opening period T of the drainage solenoid valve 11 is set to the shortest period in step S64, and the flow rates of the fuel gas and the air are increased in step S66 (at this time, the gas utilization rate). Decreases by c%), and the process returns to step S60.

If it is determined in step S62 that the internal pressure P is equal to or higher than the pressure set value Pl, it is determined in step S68 whether the internal pressure P is lower than the pressure set value Ph. If the internal pressure P is lower than the pressure set value Ph, in step S72, the opening cycle T of the drainage solenoid valve 11 is set to T = P × a + using the internal pressure P.
b (a and b are appropriate constants), and the step S
At 74, the flow rates of the fuel gas and air are increased (at this time, the gas utilization rate decreases by d%), and the process returns to step S60.

If it is determined in step S68 that the internal pressure P is equal to or higher than the pressure set value Ph, in step S70, the open period T of the drainage solenoid valve 11 is set to the longest period, and the flow rates of the fuel gas and air are set to the normal flow rate. Then, the process returns to step S60.

Next, a second embodiment of the fuel cell system according to the present invention will be described. In the first embodiment described above, the water pool and the solenoid valve are provided near the supply gas pipe mounting part outside the end plate, but in the second embodiment, an example in which the water pool is provided inside the end plate will be described. .

As shown in FIGS. 11 and 12, in the second embodiment, an end plate 30 with a water pool is provided in which a water pool 31 is provided inside the end plate, and a solenoid valve is integrated into this end plate 30. Valve block 32
It has a structure to attach. According to this embodiment, the fuel cell stack can be downsized and the mechanical strength can be improved.

In addition to the above-mentioned embodiments, the lower surface of the manifold may be inclined toward the water pool by a method of inclining the manifold itself or by inclining the stack itself.

[Brief description of drawings]

FIG. 1 is a perspective view of a fuel cell stack 1 illustrating a first embodiment of a fuel cell system according to the present invention.

FIG. 2 is a diagram showing an example of each flow path of an anode (a) and a cathode (b) of a bipolar plate used in the fuel cell 2 of the present invention.

FIG. 3 is a cross-sectional view of a gas pipe and an internal manifold according to the first embodiment.

FIG. 4 is a system configuration diagram showing a configuration of a control system in the embodiment of the fuel cell system according to the present invention.

FIG. 5 is a time chart showing the relationship between the water discharge amount and the water tank internal pressure.

FIG. 6 is a time chart showing the relationship between the internal pressure of the water tank and the solenoid valve opening period, which is the period for opening the solenoid valve 11.

FIG. 7 is a time chart diagram showing an operation example of suppressing water clogging by using the electromagnetic valve 11 for drainage during normal operation.

FIG. 8 is a view showing a control flowchart of a solenoid valve opening cycle at the time of startup in the embodiment.

FIG. 9 is a diagram showing a control flowchart of a solenoid valve opening cycle at the time of startup in the embodiment.

FIG. 10 is a diagram showing a control flowchart in the case of suppressing water clogging by using a solenoid valve for drainage even during normal operation.

FIG. 11 is a cross-sectional view of a gas pipe and an internal manifold according to the second embodiment.

FIG. 12 is a perspective view showing a configuration of a fuel cell stack according to a second embodiment.

[Explanation of symbols]

1 ... Fuel cell stack 2 ... cell 3 ... End plate 4 ... Fuel gas supply piping 5 ... Fuel gas exhaust pipe 6 ... Air supply piping 7 ... Air exhaust piping 8 ... Coolant supply pipe 9 ... Coolant discharge pipe 10 ... Puddle 11 ... Solenoid valve (drain valve) 12 ... Drainage pipe

Claims (11)

[Claims] 1. A fuel cell main body for generating power by an electrochemical reaction of a fuel gas and an oxidant gas, fuel gas supply means for supplying the fuel gas to the fuel cell main body, and an oxidant gas for supplying the fuel cell main body In the fuel cell system including an oxidant gas supply means for controlling, in at least one of the fuel gas passage and the oxidant gas passage of the fuel cell main body, a water reservoir for temporarily storing water, and in the gas passage A fuel cell system comprising: a water guiding unit that guides the water in the water pool to the water pool; and a drain valve that drains the water in the water pool. 2. The fuel cell according to claim 1, wherein at least one of an opening degree, a valve opening time, and a valve opening interval of the drain valve is adjusted according to the amount of water in the gas passage. system. 3. The fuel cell system according to claim 1, wherein the electric power taken out from the fuel cell main body is limited to a predetermined value or less according to the amount of water in the gas passage. 4. The fuel cell system according to claim 1, wherein the gas flow rate of at least one of the fuel gas and the oxidant gas is adjusted according to the amount of water in the gas passage. 5. A pressure detecting means for detecting a pressure is provided downstream of the drain valve, and the amount of water in the gas passage is determined based on the pressure fluctuation detected by the pressure detecting means when the drain valve is opened. The fuel cell system according to claim 2, wherein the fuel cell system is estimated. 6. The fuel cell system according to claim 5, wherein a tank is provided downstream of the drain valve, and the pressure detecting means detects the pressure in the tank. 7. The water in the water pool is drained by opening the drain valve at the time of start-up before extracting electric power from the fuel cell body. Fuel cell system. 8. The fuel cell main body comprises a stack in which a plurality of cells are stacked, and the gas passage has a manifold penetrating each cell, a gas flow path formed on an electrode surface inside each cell, and a manifold and each A connection hole for communicating a gas flow path formed on the in-cell electrode surface, wherein the water guiding means is inclined so as to decrease toward the water pool portion provided on the lower surface of the manifold. The fuel cell system according to any one of claims 1 to 7. 9. The fuel cell system according to claim 8, wherein a lower surface of the manifold is lower than a lower end portion of the connection hole. 10. The fuel cell system according to claim 9, wherein the lower end portion of the connection hole is provided with an inclination decreasing toward the manifold. 11. The water pool part is provided in the vicinity of a connection part of a gas pipe of the fuel gas or the oxidant gas to the fuel cell main body, wherein the water pool part is provided. The fuel cell system according to the item.