JP5219394B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system such as a polymer electrolyte fuel cell using, for example, hydrogen and air, and more particularly to improvement of discharge of residual gas on the anode (hydrogen electrode) side.

  Conventionally, a fuel cell system mounted on a vehicle or the like is formed by a solid polymer fuel cell in which an anode (hydrogen electrode) and a cathode (oxygen electrode) are disposed so as to sandwich a solid polymer electrolyte membrane from both sides. Is done.

  In the polymer electrolyte fuel cell, when hydrogen gas is supplied as fuel gas to the anode and air is supplied to the cathode, an electrochemical reaction occurs, and an electromotive force is generated between the anode and the cathode.

  As is well known, this polymer electrolyte fuel cell fuel cell system is generating power due to initial defects in the solid polymer electrolyte membrane, pinholes due to durability deterioration, gasket defects, etc. In addition, a “cross leak” occurs in which nitrogen at the cathode permeates the solid polymer electrolyte membrane and leaks to the anode side.

  When the “cross leak” occurs, the nitrogen that has permeated the solid polymer electrolyte membrane accumulates on the anode side, so that the hydrogen concentration on the anode side of the fuel cell decreases, and the power generation efficiency of the fuel cell system significantly decreases. To do.

  Therefore, every time the hydrogen concentration (hydrogen gas pressure) decreases to a predetermined value (lower limit) due to power generation, a part of the remaining gas on the anode side is discharged to the outside, and the unnecessary remaining gas is removed together with the hydrogen gas. Therefore, the hydrogen concentration is increased to maintain a hydrogen concentration that does not hinder power generation.

  The remaining gas on the anode side after discharging the hydrogen concentration to the lower limit value is discharged without waiting until the hydrogen concentration decreases to the lower limit value. This is because there is a possibility of causing various adverse effects, and the power generation efficiency (fuel efficiency of power generation) itself is also lowered.

  By the way, in a hydrogen circulation type fuel cell system which is an example of a fuel cell system of this type of polymer electrolyte fuel cell, in order to suppress wasteful hydrogen gas discharge due to discharge of residual gas on the anode side, anode circulation The hydrogen gas contained in the residual gas (anode exhaust gas) discharged by providing an electrochemical hydrogen pump in the path is selectively taken out and returned to the anode, and only the remaining impurities of the residual gas are discharged out of the circulation path. It has been proposed. In this case, wasteful discharge of hydrogen gas can be reduced, and safety can be enhanced while suppressing a decrease in power generation efficiency (see, for example, Patent Document 1).

On the other hand, the applicant of the present application, in a fuel cell system of this type of polymer electrolyte fuel cell, discharges water (generated water) staying on the anode side of the fuel cell by power generation without using a pump or the like A simple and inexpensive configuration has already been filed (Japanese Patent Application No. 2005-310221, Japanese Patent Application No. 2006-074825).
JP 2006-19120 (abstract, [0002]-[0004], [0009]-[0010], [0016]-[0024], FIG. 1 etc.)

  The conventional system of Patent Document 1 needs to be provided with an electrochemical hydrogen pump in the anode circulation path, resulting in a complicated configuration and a problem of increasing system cost and complication of control.

  In addition, although the amount of hydrogen gas discharged outside the circulation path is reduced due to the action of the electrochemical hydrogen pump, the concentration of hydrogen gas in the residual gas at the time of discharge is as low as possible from the viewpoint of improving safety. Is desirable. Therefore, even in the conventional system of Patent Document 1, it is necessary to wait until the hydrogen concentration on the anode side is sufficiently lowered by power generation before discharging the residual gas. In this case, the remaining gas is discharged after waiting until the hydrogen concentration on the anode side becomes sufficiently low due to normal power generation, so the power generation period in a low hydrogen concentration state becomes longer, and in fact sufficient power generation efficiency Cannot be obtained. That is, even in the conventional system of Patent Document 1, it is difficult to sufficiently increase both power generation efficiency and safety.

  Moreover, the application range is limited to a hydrogen circulation type fuel cell system in which residual gas (anode exhaust gas) discharged from the anode outlet of the fuel cell is circulated to the anode inlet side and reused, and there is no fuel cell having an anode circulation path. There are problems that are not applicable to the system.

  In the conventional system having another configuration, such as the already-filed fuel cell system of the present applicant, the remaining gas is discharged after waiting until the hydrogen concentration on the anode side of the fuel cell becomes sufficiently low by power generation. Therefore, it is difficult to make both power generation efficiency and safety sufficiently high.

  The present invention has a simple and inexpensive configuration that can be applied to a fuel cell system of any system / configuration, so that the remaining gas on the anode side of the fuel cell can be discharged safely whenever necessary. It is an object of the present invention to provide a novel anode-side residual gas discharge structure that can sufficiently increase both safety and safety.

In order to achieve the above object, a fuel cell system according to the present invention is provided in an anode upper flow path from a fuel tank to the anode side of the fuel cell, and supplies fuel gas from the fuel tank to the anode side of the fuel cell. Supply control means for adjusting the discharge, and discharge control means for opening and closing the anode lower flow path from the anode side of the fuel cell to the discharge port, and intermittently discharging the residual gas on the anode side of the fuel cell, the supply The control means shuts off or reduces the supply of fuel gas from the fuel tank to the anode side of the fuel cell before discharging the residual gas to maintain the fuel cell in a power generation state, and controls the anode side in the fuel cell. The discharge control means opens the anode lower flow path after the anode side of the fuel cell is in the reduced pressure state, and the residual gas Is intended to discharge, if reduced to set the concentration of the fuel gas is gas pressure Px of the anode side of the fuel cell, the anode side of the fuel in the cell by the pressure reducing function of the supply control means in a reduced pressure state, wherein After the fuel gas on the anode side of the fuel cell decreases to a concentration of gas pressure Py (<Px), the discharge control means opens the anode lower flow path to discharge the residual gas, and the anode side of the fuel cell When the fuel gas drops to the lower limit concentration of the gas pressure Pmin (<Py), the discharge is stopped, and the fuel gas is supplied to the anode side of the fuel cell by the supply control means at the initial gas pressure Pmax (> Px). The supply is performed until the initial concentration is reached (claim 1).

Further, the fuel cell system of the present invention reduces the anode side in the fuel cell by the pressure reducing function of the supply control means before entering the tunnel when the approach of the tunnel is found based on the road information of the car navigation. The discharge control means opens the anode lower flow path to discharge the residual gas, and the supply control means supplies the initial concentration of the fuel gas to the anode side of the fuel cell. which may be (claim 2).

  According to the first aspect of the present invention, when the remaining gas on the anode side is not discharged, the anode side of the fuel cell is put into a reduced pressure state by the pressure reducing function of the supply control means provided in the anode upper flow path. That is, the supply of fuel gas from the fuel tank to the anode side of the fuel cell is interrupted or reduced to maintain the fuel cell in the power generation state.

  Then, the remaining gas (hydrogen and nitrogen) on the anode side of the fuel cell is “concentrated” by power generation of the fuel cell in a state where the supply of the fuel gas is cut off or reduced.

Incidentally, the term "enriched" the residual gas in the specification and the like of the present application, by small block or decrease the supply of fuel gas to the anode side, the hydrogen concentration (partial pressure) constituting the remaining gas in the anode side only To reduce the total gas pressure on the anode side.

  Then, the fuel gas concentration (hydrogen concentration) is lowered by bringing the anode side into a reduced pressure state of the total gas pressure by “concentration” of the residual gas, so that a safe state is achieved.

  Further, in a safe state where the anode side fuel gas concentration is low, the discharge control means opens the anode lower flow path and discharges the anode side residual gas.

  In this case, before discharging the remaining gas on the anode side, the supply of fuel gas to the fuel cell is cut off or reduced, so that the remaining gas on the anode side is “concentrated” and its total pressure is reduced. Therefore, the anode side fuel gas concentration is set to a safe state and the residual gas is discharged, so that the anode side residual gas can be safely discharged whenever necessary.

  Then, a decompression function is added to the supply control means for the anode upper flow path, and a simple discharge control means for opening and closing the lower flow path is provided in the anode lower flow path, which can be formed with a simple and inexpensive configuration. The present invention can be applied not only to the circulation type fuel cell system, but also to any type of fuel cell system including the fuel cell system already filed by the present applicant.

Therefore, the simple and inexpensive configuration applicable to any type of fuel cell system can safely discharge the anode-side residual gas whenever necessary , regardless of whether the vehicle is running or stopped. During normal power generation, the remaining gas is discharged early in a state where the fuel gas concentration on the anode side of the fuel cell is high, and the fuel gas concentration on the anode side of the fuel cell is refreshed to the original high concentration state to improve the power generation efficiency. It is possible to provide a novel anode-side residual gas discharge structure that is sufficiently high in both safety and in a state where the hydrogen gas concentration is low until the gas pressure Px is reduced to the gas pressure Py as in the conventional system. without being maintained for a long time for power generation, Ru can significantly improve the power generation efficiency.

According to the invention of claim 2, when it is found that the approach of the tunnel where fuel gas is liable to stay and discharge of the remaining gas is not preferable on the basis of the road information of the car navigation, it is forcibly made before entering the tunnel. Transition to the decompressed state, discharge the residual gas on the anode side of the fuel cell, refresh the fuel gas concentration to the initial concentration state, and do not discharge the residual gas on the anode side of the fuel cell in the tunnel It is possible to further improve the performance.

  Next, in order to describe the present invention in more detail, an embodiment will be described in detail with reference to FIGS.

  FIG. 1 is a block diagram of the anode side of the fuel cell system, and FIG. 2 is a flowchart of the anode control of FIG. FIG. 3 is an explanatory view of the time change of the anode side gas partial pressure of the fuel cell of FIG. 1, and FIG. 4 is an explanatory view of the time change of the anode side gas partial pressure of the fuel cell of the conventional system for comparison.

  The fuel cell system of FIG. 1 is an improvement of the above-mentioned solid polymer type fuel cell fuel cell system of the present applicant, and is mounted on a vehicle such as a light vehicle.

  In FIG. 1, reference numeral 1 denotes a solid polymer fuel cell (FC) using hydrogen and oxygen, which is supplied to the fuel gas supplied to the anode (hydrogen electrode) side and to the cathode (air electrode) side. An electrochemical reaction is generated with the oxygen in the air through the polymer electrolyte membrane to generate power.

  2 is a fuel tank upstream of the anode of the fuel cell 1, 3 is its main stop valve, 4, 5 and 6 are regulators, supply valves, and pressure sensors provided in the anode upper flow path 7 from the fuel tank 2 to the fuel cell 1. It is.

One of the regulator 4 and the supply valve 5 forms the supply control means of the present invention, and the supply of hydrogen gas (fuel gas) from the fuel tank 2 to the anode side of the fuel cell 1 is adjusted (including opening and closing). Further, by having the pressure reducing function of the present invention, the supply of hydrogen gas from the fuel tank 2 to the anode side of the fuel cell 1 is shut off by closing the supply valve 5 before discharging the residual gas of the fuel cell 1, or by squeezing regulator 4, adjusting the anode-side gas total pressure to reduce the hydrogen gas pressure. The supply valve 5 is also used for controlling the discharge of the generated water.

  8 is an anode lower flow path from the fuel cell 1 to a normally closed exhaust valve 10 and a drain valve 11 described later, and 9 is a rectangular box or cylindrical container of an appropriate size provided in the anode lower flow path 8. A water reservoir for storing the generated water discharged from the fuel cell 1 is formed.

  Reference numeral 10 denotes an exhaust valve provided in an insertion passage (one end portion of the anode lower flow path 8) at the upper peripheral surface of the container 9, which forms the discharge control means of the present invention and opens and closes the anode lower flow path 8 to open the fuel. The residual gas on the anode side of the battery 1 is discharged intermittently. 11 is a drain valve 11 provided in the insertion passage (the other end portion of the anode lower flow path 8) at the lower peripheral surface of the container 9 and is opened only when the stored water in the container 9 is discharged.

  The valves 3, 5, 10, 11 and the regulator 4 are in a state in which white portions are open and in a state in which black portions are closed, and opening / closing and the like are controlled by a control ECU (not shown).

  Next, for the sake of simplicity, the supply of the fuel gas (hydrogen gas) from the fuel tank 2 to the anode side of the fuel cell 1 is shut off by the pressure reducing function of the supply valve 5 before the remaining gas of the fuel cell 1 is discharged. The operation of the fuel cell system of FIG. 1 will be described with reference to FIGS.

  First, when power generation is commanded in conjunction with the turn-on of the ignition key, etc., the exhaust valve 10 and the drain valve 11 are closed before the start of power generation due to the “pressurization” of the loop of steps S1 and S2 in FIG. The high-pressure hydrogen gas that has passed through the main stop valve 3 of the fuel tank 2 is supplied to the anode side of the fuel cell 1 through the regulator 4, the supply valve 5, and the pressure sensor 6. Increases to the concentration (initial concentration) of the set initial gas pressure (upper limit pressure) Pmax shown in FIG. 3B, and the fuel cell 1 enters the “initial” state of FIG. 3A shows the partial pressure state on the anode side of the fuel cell 1, where the hatched portion α is the hydrogen partial pressure and the hatched portion β is the nitrogen partial pressure. In this case, the sum of the hydrogen partial pressure α and the nitrogen partial pressure β is the total gas pressure on the anode side. Further, the solid line in FIG. 3B shows the change in the hydrogen gas pressure (hydrogen partial pressure) on the anode side of the fuel cell 1.

  When the "initial" hydrogen partial pressure state is reached, the process proceeds from step S2 in FIG. 2 to step S3, and the high-pressure hydrogen gas that has passed through the main stop valve 3 of the fuel tank 1 is transferred by the loop of steps S3 and S4. The pressure is adjusted appropriately by the regulator 4 and supplied to the anode side of the fuel cell 1 through the supply valve 5 and the pressure sensor 6 by quantitative control in consideration of power generation consumption.

  At this time, the fuel cell 1 starts power generation by an electrochemical reaction through a polymer electrolyte membrane between hydrogen gas supplied to the anode side and oxygen (air) supplied to the cathode side, and FIG. It shifts to “steady-state” normal power generation.

  Then, while power generation is continued while supplying a certain amount of hydrogen gas to the anode side of the fuel cell 1 by “steady” normal power generation, nitrogen at the cathode of the fuel cell 1 permeates the polymer membrane and returns to the anode side. When accumulated, as shown in FIG. 3B, the hydrogen partial pressure on the anode side of the fuel cell 1 gradually decreases, and the hydrogen concentration (fuel gas concentration) decreases.

  Next, for example, in “normal” normal power generation, a timer set time of “initial” period τ1 + “steady” period τ2 based on “initial” start or period τ2 based on “steady” start When (usually time in minutes) elapses and the hydrogen gas concentration on the anode side decreases to the set concentration of the gas pressure Px and before the remaining gas on the anode side is discharged, the remaining gas on the anode side of the fuel cell 1 2 is shifted from step S4 in FIG. 2 to step S5 to shift to “depressurization” in FIG.

  When this “decompression” occurs, the supply valve 5 is closed by the loop of steps S5 and S6 in FIG. 2, and the supply of hydrogen gas from the fuel tank 2 to the anode side of the fuel cell 1 is shut off, and the fuel cell 1 generates power. Maintained in a state. At this time, on the anode side of the fuel cell 1, the partial pressure of the gas is rapidly reduced as shown in FIG. Concentration decreases.

  Then, for example, the time τ3 set by the timer elapses, and the hydrogen gas concentration on the anode side of the fuel cell 1 decreases to the safe lower limit concentration of the set gas pressure Py, as shown in the blank portion γ in FIG. When the hydrogen gas on the anode side of the fuel cell 1 decreases (the blank portion γ indicates the disappearance ratio of the hydrogen gas) and the anode side of the fuel cell 1 is in a reduced pressure state, the process proceeds from step S6 to step S7 in FIG. The “discharge” state shown in FIG. At this time, the total gas pressure on the anode side of the fuel cell 1 is higher than the atmospheric pressure even in the reduced pressure state.

  Then, in the “exhaust” state, the exhaust valve 10 is opened by the loop of steps S7 and S8 in FIG. 2, and a part of the residual gas on the anode side of the fuel cell 1 is exhausted from the anode lower flow path 8 in the period τ4. It passes through the valve 10 and is discharged out of the system through the discharge port 8a. A hatched portion δ1 in FIG. 3A indicates the hydrogen gas discharge rate, and a hatched portion δ2 in FIG. 3A indicates the nitrogen gas discharge rate.

  Further, for example, when the period τ4 elapses and the hydrogen gas concentration on the anode side of the fuel cell 1 decreases to the safe lower limit concentration of the set gas pressure (lower limit value) Pmin, the process proceeds from step S8 in FIG. 2 to step S9.

  Then, unless termination of power generation is instructed, the process returns from step S9 in FIG. 2 to step S1, the exhaust valve 10 is closed, the supply valve 5 is opened, and the process proceeds to “pressurization” in FIG. At this time, with the exhaust valve 10 and the drain valve 11 closed, the high-pressure hydrogen gas that has passed through the main stop valve 3 of the fuel tank 2 passes through the regulator 4, the supply valve 5, and the pressure sensor 6. Supplied to the anode side.

  Then, when the hydrogen gas concentration of the entire anode side of the fuel cell 1 rises to the original initial gas pressure Pmax during the “pressurization” period τ 5, the above-described “initial” state is obtained again. At this time, as shown in FIG. 3 (a), the blank portion γ and the shaded portions δ1, δ2 are replaced with hydrogen gas, and the hydrogen gas concentration on the anode side of the fuel cell 1 is refreshed to the original high concentration state of the gas pressure Pmax. Is done.

  Thereafter, the fuel cell system of FIG. 1 continues power generation in a cycle operation in which the transition is made in order of “initial”, “steady state”, “decompression”, “discharge”, and “pressurization”.

  By the way, during power generation, the generated water generated on the cathode side of the fuel cell 1 due to the electrochemical reaction between hydrogen and oxygen is reversely diffused and mixed into the anode side of the fuel cell 1 through the polymer electrolyte membrane.

  When the mixed generated water is left and power generation is continued for a long period of time, the generated water accumulates on the anode side of the fuel cell 1, and the hydrogen gas concentration on the anode side gradually decreases due to the accumulation of the generated water. The battery 1 is damaged.

  Therefore, when the wet state of the anode side of the fuel cell 1 due to the accumulation of the generated water is detected by control different from the refreshing of the hydrogen gas concentration on the anode side of the fuel cell 1, the supply valve 5 is closed and the supply valve is closed. 5. The power generation of the fuel cell 1 is performed with the exhaust valve 10 and the drain valve 11 closed, and the supply valve 5 is opened after the inside of the fuel cell 1 is in a decompressed state, and hydrogen gas is supplied into the fuel cell 1 in the decompressed state. The generated water on the anode side of the fuel cell 1 is injected into the container 9 and then the drain valve 11 is opened to discharge the generated water from the drain port 8b to the outside of the system.

  In the case of the fuel cell system of the present embodiment configured as described above, before the “exhaust” of the residual gas on the anode side of the fuel cell 1, the “pressure reduction” that does not exist in the conventional system causes The pressure reducing function (closed) of the supply valve 5 as the provided supply control means operates, and the fuel cell 1 is brought into a power generation state in a state where the supply of hydrogen gas from the fuel tank 2 to the anode side of the fuel cell 1 is shut off. Maintain, “concentrate” the remaining gas on the anode side of the fuel cell 1, quickly reduce the total gas pressure on the anode side to reduce the hydrogen concentration (fuel gas concentration) to a safe state, and then control the emission The exhaust valve 10 as a means is opened to discharge the remaining gas on the anode side.

  Therefore, unlike the conventional system, there is no need to wait for the hydrogen gas concentration in the fuel cell 1 to naturally drop to a safe concentration (gas pressure Py) by normal power generation, and the discharge of the residual gas on the anode side of the fuel cell 1 can be performed. When necessary, the remaining gas on the anode side can be safely discharged by performing “decompression”.

  Moreover, the gas pressure Px that shifts to “decompression” is higher than the gas pressure Py of “exhaust”, and accordingly, the “steady” period τ2 is generated in the fuel cell 1 by “normal” normal power generation as in the conventional system. This is shorter than when waiting for the hydrogen gas concentration to naturally drop to a safe gas pressure Py. As a result, the fuel cell 1 generates power only when the hydrogen gas concentration is higher than the gas pressure Px, and the power generation efficiency of the fuel cell 1 is also improved.

  Since the opening / closing control of the supply valve 5 provided in the anode upper flow path 7 and the exhaust valve 10 provided in the anode lower flow path 8 may be performed, the fuel cell system can be applied to any system / configuration. It is realized with a simple and inexpensive configuration.

  Therefore, a simple and inexpensive configuration that can be applied to any type of fuel cell system and configuration allows the remaining gas on the anode side of the fuel cell 1 to be safely discharged whenever necessary, thereby improving power generation efficiency. It is possible to provide a novel anode side residual gas discharge structure capable of sufficiently increasing both safety.

  For comparison, FIG. 4 shows a power generation cycle and a partial pressure state of the conventional system. 4A shows a partial pressure state on the anode side of the fuel cell 1 corresponding to FIG. 3A, and FIG. 4B shows hydrogen gas on the anode side of the fuel cell 1 corresponding to FIG. 3B. The change in pressure (hydrogen partial pressure) is shown.

As shown in FIG. 4, the conventional system continues power generation with a cycle operation in which “initial”, “steady”, “discharge”, and “pressurization” are one cycle, and fuel cell with “normal” normal power generation. hydrogen gas concentration in 1 proceeds to "drain" wait for the drops naturally safe concentrations (gas pressure Py). In FIG. 3, “initial”, “steady”, “discharge”, and “pressurization” periods τ11, τ21, τ31, and τ51 correspond to the periods τ1, τ2, τ3, and τ5 in FIG. Corresponds to one period Ta. Also, the shaded portions δ11 and δ21 in FIG. 3A correspond to the shaded portions δ1 and δ2 in FIG.

  As is clear from a comparison between FIG. 3 and FIG. 4, for example, by setting the gas pressure Px in FIG. 3B to a gas pressure as close to the initial gas pressure Pmax as possible, “ The “steady” period τ2 is much shorter than the period τ21 of the conventional system, and power generation is continued at a period Ta shorter than one period Tb of the conventional system. At this time, the period τ2 is short, and the fuel cell 1 repeats power generation in a state where the hydrogen gas concentration is higher than the gas pressure Px, and the hydrogen gas concentration is low until the gas pressure Px is reduced to the gas pressure Py as in the conventional system. The power generation efficiency is remarkably improved without being maintained for a long time in the power generation in the state. Note that the higher the gas pressure Px, the higher the power generation efficiency. However, the hydrogen gas refresh effect per “discharge” is reduced accordingly. Therefore, it is preferable to determine the gas pressure Px based on the balance between the power generation efficiency and the refresh effect of the hydrogen gas concentration on the anode side.

  Moreover, since the residual gas on the anode side of the fuel cell 1 can be discharged whenever necessary and the hydrogen gas concentration can be refreshed to the “initial” high concentration state, for example, based on the road information of the car navigation mounted on the vehicle, When the hydrogen gas approaches a tunnel-like structure or the like in which hydrogen gas tends to stay and discharge of residual gas is not desirable, the gas pressure Px is set to the current hydrogen gas pressure (detected value or elapsed time) on the anode side of the fuel cell 1. The gas pressure is temporarily changed to the following gas pressure, and the residual gas on the anode side of the fuel cell 1 is forcibly shifted from “steady” to “depressurized” before entering a tunnel-like structure. The hydrogen gas concentration is refreshed to a high initial state and the remaining gas on the anode side of the fuel cell 1 is not discharged in the structure to further improve safety. Rukoto is also possible.

  In addition, based on the setting and variable adjustment of the gas pressure Px, the remaining gas on the anode side of the fuel cell 1 can be safely discharged whenever necessary during the generation of power, regardless of whether the vehicle is running or stopped. The hydrogen gas concentration on the anode side of the battery 1 can be refreshed to the original high initial state.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof, for example, hydrogen on the anode side of the fuel cell 1 Instead of indirectly detecting the increase or decrease of the gas pressure to each gas pressure Pmax, Px, Py, Pmin in FIG. 3B from the passage of the time set by the timer as in the above embodiment, Actually, a hydrogen concentration sensor, a hydrogen gas pressure sensor, etc. may be provided to detect directly from the concentration and gas pressure of the hydrogen gas on the anode side of the fuel cell 1, and in this case, there is an advantage that the management accuracy of hydrogen gas is improved. is there.

  In the above embodiment, the supply of the fuel gas (hydrogen gas) from the fuel tank 2 to the anode side of the fuel cell 1 is shut off by the pressure reducing function of the supply valve 5 before discharging the residual gas of the fuel cell 1. Although the case where the total gas pressure on the anode side is reduced and the hydrogen concentration is reduced has been described, the regulator 4 reduces the pressure from the fuel tank 2 to the anode side of the fuel cell 1 before discharging the residual gas from the fuel cell 1. The fuel gas (hydrogen gas) may be reduced to reduce the total gas pressure on the anode side to reduce the hydrogen concentration. In this case, the regulator 4 forms the supply control means of the present invention.

  Furthermore, each period τ1 to τ5 and one cycle Ta in FIG. 3 may be variously set according to the performance of the fuel cell 1 and the like, and any control means may be used. .

  The present invention is not limited to, for example, a fuel cell system in which the container 9 and the drain valve 11 in FIG. 1 are omitted, and the above-described hydrogen circulation type fuel cell system, but also a phosphoric acid type or molten carbonate type fuel cell. The present invention can also be applied to a fuel cell system of a reforming type or the like. In this case, the fuel gas may of course be other than hydrogen gas, and of course, the fuel cell system mounted on the vehicle and the fuel cell system for various uses may be used.

1 is a block diagram of a fuel cell system according to an embodiment of the present invention. It is a flowchart of the anode control of FIG. It is explanatory drawing of the time change of the anode side gas partial pressure of the fuel cell of FIG. It is explanatory drawing of the time change of the anode side gas partial pressure of the fuel cell of the conventional system for a comparison.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel tank 4 Regulator 5 Supply valve 7 Anode upper flow path 8 Anode lower flow path 8a Outlet 10 Exhaust valve

Claims (2)

A supply control means for adjusting supply of fuel gas from the fuel tank to the anode side of the fuel cell, provided in an anode upper flow path from the fuel tank to the anode side of the fuel cell;
A discharge control means for opening and closing the anode lower flow path from the anode side of the fuel cell to the discharge port, and for intermittently discharging the residual gas on the anode side of the fuel cell;
The supply control means shuts off or reduces the supply of fuel gas from the fuel tank to the anode side of the fuel cell before discharging the residual gas to maintain the fuel cell in a power generation state. It has a pressure reducing function that makes the anode side in a reduced pressure state,
The discharge control means opens the anode lower flow path after the anode side of the fuel cell is in the reduced pressure state and discharges the residual gas ,
When the fuel gas on the anode side of the fuel cell decreases to a set concentration of the gas pressure Px, the pressure reducing function of the supply control means causes the anode side in the fuel cell to be in a reduced pressure state, and the fuel cell anode side After the fuel gas has dropped to the concentration of gas pressure Py (<Px), the discharge control means opens the anode lower flow path to discharge the remaining gas, and the fuel gas on the anode side of the fuel cell is gas. The discharge is stopped when the pressure Pmin (<Py) decreases to the lower limit concentration, and the fuel gas is supplied to the anode side of the fuel cell by the supply control means until the initial concentration of the initial gas pressure Pmax (> Px) is reached. A fuel cell system. When the approach of the tunnel is determined based on the road information of the car navigation, before entering the tunnel, the anode side in the fuel cell is forcibly shifted to a reduced pressure state by the pressure reducing function of the supply control means, and the discharge control means 2. The fuel cell according to claim 1, wherein the anode lower flow path is opened to discharge the residual gas, and the fuel gas having an initial concentration is supplied to the anode side of the fuel cell by the supply control means. system.

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