JP2006004680A - Fuel cell system and transportation equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system and a transport device using the same, in which liquid discharged from the fuel cell can be effectively reused without waste.
SOLUTION: A fuel cell system 10 includes a fuel cell 12 that generates electric energy by an electrochemical reaction, an aqueous solution tank 18 that contains an aqueous methanol solution S, and a water tank into which exhaust gas containing moisture discharged from the fuel cell 12 is introduced. 44, a water level sensor 54 for detecting the amount of water in the water tank 44, a water pump 60 for returning the water in the water tank 44 to the aqueous solution tank 18, and a CPU for controlling the operation of each component of the fuel cell system 10. . In the fuel cell system 10, the amount of water in the water tank 44 is detected by the water level sensor 54 before the start of power generation. If the amount is above a predetermined amount, the water pump 60 is driven to return the water in the water tank 44 to the aqueous solution tank 18. Let
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system and a transport device using the same, and more specifically to a fuel cell system that collects liquid discharged from the fuel cell and a transport device such as a motorcycle using the fuel cell system.

  In general, in a fuel cell system, a technique for recovering liquid discharged from the fuel cell has been proposed. For example, Patent Document 1 discloses a technique in which water stored in a water tank at the end of power generation in a fuel cell system is transferred to an aqueous solution tank that stores an aqueous methanol solution.

There is also known a fuel cell system that introduces exhaust gas discharged from a fuel cell together with water into a water tank when an air pump that supplies air to the fuel cell is driven. In such a fuel cell system, water is stored in a water tank, and exhaust gas is discharged from an outlet provided in the water tank.
JP 2000-21430 A

  In the technique of Patent Document 1, water in the water tank is transferred to the aqueous solution tank and unnecessary water is discharged, so that the water tank is empty at the end of power generation. Seeps from the fuel cell and accumulates in the water tank. When exhaust gas is discharged from the outlet of the water tank, the water stored in the water tank after power generation ends is scraped by the swirling flow of the exhaust gas introduced into the water tank when the air pump is driven at the next power generation start. There was a risk of being lifted and discharged from the outlet. As a result, in a fuel cell system that requires water for power generation, the water discharged from the fuel cell may not be effectively reused.

  Further, in the fuel cell system, water is supplied to the fuel cell so that the electrolyte does not dry after the completion of power generation, and the water that exudes from the fuel cell by crossover after power generation is stored in the water tank. In particular, some fuel cell systems that use methanol as the fuel supply an aqueous methanol solution to the fuel cell after the end of power generation to keep the electrolyte moist. In this case, the methanol aqueous solution is discharged at the start of the next power generation, and methanol is used. There was a risk of reducing the rate.

  Therefore, a main object of the present invention is to provide a fuel cell system and a transport device using the same, which can effectively reuse liquid discharged from the fuel cell without waste.

  In order to achieve the above object, a fuel cell system according to claim 1 is a fuel cell that generates electric energy by an electrochemical reaction, an air pump that supplies air necessary for generating electric energy to the fuel cell, and a fuel cell. A first tank into which liquid and exhaust gas discharged from the tank are introduced; a discharge port provided in the first tank for discharging exhaust gas introduced into the first tank from the first tank; A sensor for detecting the amount of liquid, a second tank to which the liquid in the first tank is transferred, a liquid pump for transferring the liquid in the first tank to the second tank, and a sensor in the first tank that is detected by the sensor before the start of power generation When the amount of liquid is larger than a predetermined amount, control means is provided for executing a process of transferring the liquid in the first tank to the second tank by the liquid pump before driving the air pump.

  The fuel cell system according to claim 2 includes a fuel cell that generates electric energy by an electrochemical reaction, an air pump that supplies air necessary for generating electric energy to the fuel cell, and a liquid and exhaust gas discharged from the fuel cell. A first tank to be introduced; a discharge port provided in the first tank for exhausting exhaust gas introduced into the first tank from the first tank; a sensor for detecting the amount of liquid in the first tank; The second tank to which the liquid in the tank is transferred, the liquid pump for transferring the liquid in the first tank to the second tank, and the case where the amount of liquid in the first tank detected by the sensor after power generation is stopped is greater than a predetermined amount. Control means for executing a process of transferring the liquid in one tank to the second tank by a liquid pump is provided.

  According to a third aspect of the present invention, there is provided the fuel cell system according to the first aspect, wherein the control means detects the first tank when the amount of liquid in the first tank detected by the sensor after power generation is stopped is greater than a predetermined amount. A process of transferring the liquid in the tank to the second tank by a liquid pump is performed.

  According to a fourth aspect of the present invention, there is provided the fuel cell system according to the second or third aspect, wherein the control means is provided when the amount of liquid in the first tank detected by the sensor after power generation is stopped is greater than a predetermined amount. The process of transferring the liquid in one tank to the second tank by a liquid pump is performed at predetermined time intervals.

  The fuel cell system according to claim 5 is the fuel cell system according to any one of claims 1 to 4, wherein the second tank is an aqueous solution tank that stores an aqueous methanol solution to be supplied to the fuel cell. To do.

  The fuel cell system according to claim 6 is the fuel cell system according to claim 5, wherein the fuel cell is provided below the aqueous solution tank.

  The fuel cell system according to claim 7 is the fuel cell system according to any one of claims 1 to 6, wherein the fuel cell system is a direct methanol fuel cell system.

  The transportation device according to claim 8 is characterized in that the fuel cell system according to any one of claims 1 to 7 is used.

  In the fuel cell system according to claim 1, if the amount of liquid in the first tank detected before the start of power generation is larger than a predetermined amount, it will be discharged from the discharge port by the exhaust gas accompanying the drive of the air pump. The liquid in the first tank is transferred to the second tank before the air pump is driven. Therefore, the discharge of the liquid from the discharge port at the start of power generation can be suppressed, and the liquid discharged from the fuel cell can be effectively reused without waste.

  In the fuel cell system according to claim 2, when the amount of liquid in the first tank detected after the end of power generation is larger than a predetermined amount, it is discharged from the discharge port by the exhaust gas accompanying the driving of the air pump at the next start of power generation. The liquid in the first tank will be transferred to the second tank. Therefore, the liquid discharge from the discharge port at the start of the next power generation can be suppressed, and the liquid discharged from the fuel cell can be effectively reused without waste.

  In the fuel cell system according to claim 3, when the amount of liquid in the first tank detected after the end of power generation is larger than a predetermined amount in addition to before the start of power generation, the exhaust gas accompanying the driving of the air pump causes the discharge from the outlet. The liquid in the first tank that will be discharged is transferred to the second tank. Therefore, the liquid discharged from the fuel cell before the end of power generation and the liquid that exudes from the fuel cell after the end of power generation can be suppressed from being discharged, and the liquid discharged from the fuel cell can be reused more reliably.

  In the fuel cell system according to claim 4, when the amount of liquid in the first tank detected every predetermined time after the end of power generation is larger than the predetermined amount, the liquid in the first tank is always in the second tank. Moved to. In other words, the liquid amount in the first tank is adjusted so as not to exceed a predetermined amount every predetermined time after the end of power generation. Therefore, the liquid that oozes out from the fuel cell after the end of power generation does not reach the outlet of the first tank and is discharged, and the liquid that oozes out from the fuel cell after the end of power generation can be reliably reused.

  In the fuel cell system according to claim 5, since the aqueous solution tank for storing the aqueous methanol solution to be supplied to the fuel cell is a second tank, there is no need to separately provide a second tank, and the fuel can be produced without increasing the size of the system. The liquid discharged from the battery can be effectively reused without waste.

  According to the present invention, the liquid that oozes out from the fuel cell after power generation can be effectively reused without waste. Therefore, as described in claim 6, the fuel cell is provided below the aqueous solution tank. However, the methanol utilization rate of the fuel cell system in which the aqueous methanol solution is supplied to the fuel cell is not lowered.

  In the direct methanol fuel cell system, since the aqueous methanol solution is directly supplied to the fuel cell, a reformer is not required, and the system configuration can be simplified. For these reasons, the direct methanol fuel cell system is suitably used for devices that require portability and devices that require downsizing. In order to improve the portability of equipment using direct methanol fuel cell systems and direct methanol fuel cell systems, materials necessary for power generation are provided within the fuel cell system as much as possible without relying on external supply. There is a need. Since the present invention can effectively reuse the liquid discharged from the fuel cell without waste, it is particularly effective in a direct methanol fuel cell system suitably used for a device requiring portability as described in claim 7. .

  Since the fuel cell system described above can effectively reuse the liquid discharged from the fuel cell without waste, it is suitably used for transportation equipment in which it is difficult to secure the liquid as described in claim 8.

  According to the present invention, the liquid discharged from the fuel cell can be effectively reused without waste.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIGS. 1-4, the fuel cell system 10 of one Embodiment of this invention is comprised as a direct methanol type fuel cell system. Since the direct methanol fuel cell system does not require a reformer, it is suitably used for equipment that requires portability or equipment that requires downsizing. Here, the case where the fuel cell system 10 is used for a motorcycle which is an example of a transportation device will be described. In addition, as shown in FIG. 2, only the vehicle body frame 200 is shown about a motorcycle. The fuel cell system 10 is disposed along the vehicle body frame 200.

  Referring mainly to FIG. 1, the fuel cell system 10 includes a fuel cell 12. The fuel cell 12 includes a plurality of direct methanol fuel cells including a solid polymer membrane 12a that is an electrolyte and an anode (fuel electrode) 12b and a cathode (air electrode) 12c that sandwich the solid polymer membrane 12a from both sides in series. It is configured as a connected (stacked) fuel cell stack.

  The fuel cell system 10 also includes a fuel tank 14 that contains a high-concentration methanol fuel (an aqueous solution containing about 50 wt% of methanol), and the fuel tank 14 contains an aqueous methanol solution S through a fuel supply pipe 16. Connected to an aqueous solution tank 18. A fuel pump 20 is inserted into the fuel supply pipe 16, and the methanol fuel F in the fuel tank 14 is supplied to the aqueous solution tank 18 by driving the fuel pump 20. A water level sensor 15 is attached to the fuel tank 14 to detect the water level of the methanol fuel F in the fuel tank 14. A water level sensor 22 is attached to the aqueous solution tank 18 to detect the water level of the aqueous methanol solution S in the aqueous solution tank 18.

  The aqueous solution tank 18 is connected to the anode 12 b of the fuel cell 12 through the aqueous solution pipe 24. An aqueous solution pump 26, a heat exchanger 30 having a cooling fan 28, and an aqueous solution filter 32 are inserted into the aqueous solution pipe 24 in this order from the upstream side. The aqueous methanol solution S in the aqueous solution tank 18 is supplied toward the anode 12b by driving the aqueous solution pump 26, cooled by the heat exchanger 30 as necessary, further purified by the aqueous solution filter 32, and supplied to the anode 12b. .

  On the other hand, an air pump 34 is connected to the cathode 12 c of the fuel cell 12 via an air side pipe 36, and an air filter 38 is inserted into the air side pipe 36. Therefore, air containing oxygen from the air pump 34 is purified by the air filter 38 and then given to the cathode 12c.

  The anode 12b and the aqueous solution tank 18 are connected via a pipe 40, and the unreacted aqueous methanol solution S discharged from the anode 12b and the generated carbon dioxide are given to the aqueous solution tank 18.

  Further, a water tank 44 is connected to the cathode 12c through a pipe 42. A gas-liquid separator 48 having a cooling fan 46 is inserted in the pipe 42. By driving the air pump 34, exhaust gas containing moisture is discharged from the cathode 12 c and supplied to the water tank 44 via the pipe 42.

The aqueous solution tank 18 and the water tank 44 are connected via a CO ₂ vent pipe 50. A methanol trap 52 for separating the aqueous methanol solution S is inserted in the CO ₂ vent pipe 50. As a result, the carbon dioxide discharged from the aqueous solution tank 18 is given to the water tank 44.

  A water level sensor 54 is attached to the water tank 44 to detect the water level in the water tank 44. An exhaust gas pipe 56 is attached to the water tank 44, and carbon dioxide and exhaust gas from the cathode 12c are discharged from the exhaust gas pipe 56.

  The water tank 44 is connected to the aqueous solution tank 18 through a water reflux pipe 58, and a water pump 60 is inserted into the water reflux pipe 58. The water in the water tank 44 is appropriately returned to the aqueous solution tank 18 by driving the water pump 60. In this embodiment, the water tank 44 corresponds to the first tank, and the aqueous solution tank 18 corresponds to the second tank.

  In the aqueous solution pipe 24, a bypass pipe 62 is formed between the heat exchanger 30 and the aqueous solution filter 32. Further, in the fuel cell system 10, a concentration sensor 64 for detecting the concentration of the aqueous methanol solution S is provided in the bypass pipe 62, and a temperature sensor 66 for detecting the temperature of the fuel cell 12 is attached to the fuel cell 12. An outside air temperature sensor 68 for detecting the outside air temperature is provided in the vicinity of the air pump 34.

  As can be seen from FIGS. 2 and 3, in the fuel cell system 10, the fuel cell 12 is disposed below the aqueous solution tank 18 so that the methanol aqueous solution S flows down from the aqueous solution tank 18 by gravity even after the completion of power generation. Configured. Although the aqueous solution pump 26 is not operating after the power generation is completed, the aqueous methanol solution S flowing down from the aqueous solution tank 18 cannot be completely blocked by the aqueous solution pump 26. The aqueous methanol solution S flowing down from the aqueous solution tank 18 passes through the aqueous solution pump 26, fills the aqueous solution pipe 24, and is supplied to the anode 12b. The aqueous methanol solution S filling the anode 12 b and the pipe 40 returns to the aqueous solution tank 18 via the pipe 40.

  In this way, even after power generation is completed, by supplying the aqueous methanol solution S to the anode 12b, the solid polymer film 12a is moisturized, and a decrease in the ionic conductivity of the solid polymer film 12a when power generation is stopped is prevented. Yes. In addition, the moisture retention of the solid polymer film 12a prevents the deterioration of the solid polymer film 12a such as cracks due to drying. A part of the aqueous methanol solution S supplied to the anode 12 b after the end of power generation is discharged from the cathode 12 c by the crossover from the solid polymer film 12 a and is stored in the water tank 44.

As shown in FIG. 4, the fuel cell system 10 includes a control circuit 70.
The control circuit 70 performs necessary calculations and controls the operation of the fuel cell system 10, a normal mode clock circuit 74 that gives the normal mode clock to the CPU 72, and a low power consumption mode slower than the normal mode clock to the CPU 72. Low-consumption mode clock circuit 75 for supplying a clock, memory 76 including, for example, an EEPROM for storing a program, data, operation data, and the like for controlling the operation of the fuel cell system 10, and preventing malfunction of the fuel cell system 10 Reset IC 78, interface circuit 80 for connection with external equipment, voltage detection circuit 84 for detecting voltage in electric circuit 82 for connecting fuel cell 12 to motor 202 for driving the motorcycle, electric circuit 82 Current to detect the current flowing through The output circuit 86, an ON / OFF circuit 88 for opening and closing the electric circuit 82, a voltage protection circuit 90 for preventing overvoltage of the electric circuit 82, a diode 92 provided in the electric circuit 82, and a voltage for normal mode in the electric circuit 82 And a power supply circuit 95 for supplying the electric circuit 82 with a low consumption mode voltage.

  Detection signals from the water level sensors 15, 22, and 54 are input to the CPU 72 of the control circuit 70, and detection signals from the concentration sensor 64, the temperature sensor 66, and the outside air temperature sensor 68 are input. Further, the CPU 72 receives a detection signal from the fall switch 96 that detects the presence or absence of the fall. Further, the CPU 72 is given a signal from the input unit 98 for various settings and information input. From the input unit 98, for example, a signal that triggers the start or end of power generation is given to the CPU 72 in accordance with an ON / OFF operation to a main switch (not shown).

  The CPU 72 controls auxiliary equipment such as the fuel pump 20, the aqueous solution pump 26, the air pump 34, the heat exchanger cooling fan 28, the gas-liquid separator cooling fan 46, and the water pump 60. Further, the CPU 72 controls the display unit 100 for displaying various information and notifying the various passengers of the motorcycle.

  A secondary battery 102 is connected in parallel to the fuel cell 12. The secondary battery 102 is also connected in parallel to the motor 202. The secondary battery 102 complements the output from the fuel cell 12, is charged by the electric energy from the fuel cell 12, and gives electric energy to the motor 202 and the auxiliary machines by the discharge.

  A meter 204 for measuring various data of the motor 202 is connected to the motor 202, and the data measured by the meter 204 and the status of the motor 202 are given to the CPU 72 via the interface circuit 104.

  In this embodiment, the CPU 72 corresponds to the control means. In this embodiment, a program and data for executing the operations shown in FIGS. 7 and 8 are stored in the memory 76.

Here, the water tank 44 will be described in detail.
As shown in FIGS. 2 and 3, the water tank 44 is made of, for example, FRP, and is configured to be small in size so as to correspond to the arrangement position in the vehicle body frame 200 and is configured to bulge the lower part from the upper part. . The volume of the water tank 44 is about 500 cc.

  Referring to FIGS. 5 and 6, water pipe 44 is attached so that introduction pipes 106 and 108 and discharge pipes 110 and 112 made of, for example, SUS304 are fitted.

  The introduction pipe 106 includes a cylindrical portion 106 a that fits into the water tank 44 from the front and slightly above the water tank 44, and a substantially trumpet-shaped expanded portion 106 b that bends downward in the water tank 44. The opening area of the inlet 114b of the expansion part 106b is set larger than that of the inlet 114a of the cylindrical part 106a. A pipe 42 is connected to the cylindrical portion 106a.

  The discharge pipe 110 is a cylindrical pipe that fits into the water tank 44 from the back surface of the water tank 44, and is provided in the water tank 44 so that the discharge port 115 is positioned above the expanded portion 114 b of the introduction pipe 106. It is done. In this way, the expanding portion 106b and the discharge pipe 110 are arranged so that the introduction port 114b and the discharge port 115 do not face each other in the water tank 44. An exhaust gas pipe 56 is connected to the discharge pipe 110.

The introduction pipe 108 is a cylindrical pipe that fits into the water tank 44 from the top corner of the water tank 44, and is disposed above the discharge pipe 110 in the water tank 44. A CO ₂ vent pipe 50 is connected to the introduction pipe 118.
The discharge pipe 112 is a cylindrical pipe that fits into the water tank 44 from the back and near the bottom of the water tank 44, and the water return pipe 58 is connected to the discharge pipe 112.

Accordingly, the exhaust gas containing moisture from the cathode 12 c is introduced into the water tank 44 from the introduction pipe 106 via the pipe 42. Carbon dioxide via the aqueous solution tank 18 and the CO ₂ vent pipe 50 is introduced into the water tank 44 from the introduction pipe 108. Moisture in the water tank 44 flows into the water reflux pipe 58 via the discharge pipe 112. The exhaust gas containing carbon dioxide in the water tank 44 is discharged to the outside through the exhaust pipe 110 and the exhaust gas pipe 56.

  A water level sensor 54 composed of, for example, a float sensor for detecting the water level in the water tank 44 is provided below the expanding portion 106b. As shown in FIG. 6, the water level sensor 54 includes a sensor main body 54a and a float portion 54b attached to the sensor main body 54a. The water level sensor 54 can detect the water level in the water tank 44 by floating the float portion 54 b as the water level in the water tank 44 changes. In other words, the water level sensor 54 can detect the amount of liquid (the amount of water) in the water tank 44 based on the position of the floating float 54b.

An example of the operation of the fuel cell system 10 during power generation will be described.
At the start of power generation, the aqueous methanol solution S stored in the aqueous solution tank 18 is sent to the fuel cell 12 by driving the aqueous solution pump 26, cooled by the heat exchanger 30 as necessary, and purified by the aqueous solution filter 32. It is supplied to the anode 12b. On the other hand, air containing oxygen is sent toward the fuel cell 12 by driving the air pump 34, purified by the air filter 38, and supplied to the cathode 12c.

  In the anode 12b of the fuel cell 12, methanol and water in the aqueous methanol solution S are electrochemically reacted to generate carbon dioxide and hydrogen ions, and the generated hydrogen ions pass through the solid polymer membrane 12a to the cathode 12c. Inflow. The hydrogen ions electrochemically react with oxygen in the air supplied to the cathode 12c to generate water and electric energy.

Carbon dioxide generated at the anode 12b of the fuel cell 12 is supplied to the water tank 44 through the pipe 40, the aqueous solution tank 18, the CO ₂ vent pipe 50 and the discharge pipe 108, and is discharged from the exhaust gas pipe 56 through the discharge pipe 110. Is done.

  On the other hand, most of the water vapor generated at the cathode 12c of the fuel cell 12 is liquefied and discharged as water, but the saturated water vapor is discharged in a gas state. A part of the water vapor discharged from the cathode 12 c is liquefied by lowering the dew point with the gas-liquid separator 48. Exhaust gas (water and water vapor and unreacted air) containing moisture from the cathode 12c discharged by driving the air pump 34 is supplied to the water tank 44 via the pipe 42 and the introduction pipe 106. Further, the water moved to the cathode 12 c due to the water crossover is discharged from the cathode 12 c and supplied to the water tank 44. Further, water, carbon dioxide, and methanol generated at the cathode 12 c due to methanol crossover are discharged from the cathode 12 c and supplied to the water tank 44.

  The water crossover is a phenomenon in which several moles of water move to the cathode 12c as the hydrogen ions generated at the anode 12b move to the cathode 12c. The methanol crossover is a phenomenon in which methanol moves to the cathode 12c as hydrogen ions move to the cathode 12c. Most of the methanol that has moved to the cathode 12c reacts with the air supplied from the air pump 34 and is decomposed into water and carbon dioxide.

  Such exhaust gas containing water (water, water vapor and methanol) from the cathode 12c is introduced into the water tank 44 from the introduction port 114b of the introduction pipe 106 as shown by an arrow W in FIG. The At this time, since a strong swirling flow is generated in the water tank 44, water having a water surface height H1 (water amount of about 250 cc) or more indicated by a one-dotted line in FIG. 115 is discharged.

  The water stored in the water tank 44 is appropriately returned to the aqueous solution tank 18 via the water reflux pipe 58 by driving the water pump 60 and reused as the methanol aqueous solution S. In the fuel cell system 10, about 80% of the moisture contained in the exhaust gas discharged from the cathode 12 c is returned to the aqueous solution tank 18 via the water tank 44 so that the supply of water from the outside is not necessary.

  The liquefaction operation of water vapor by the gas-liquid separator 48 is performed by operating the cooling fan 46 to lower the dew point. This operation is controlled based on the output from the water level sensor 54 provided in the water tank 44. Also good. In this way, power consumption in the cooling fan 46 can be reduced.

Next, an example of the operation of the fuel cell system 10 before starting power generation will be described.
In the state before the start of power generation (power generation stopped state), part of the fuel cell system 10 is activated in the low consumption mode using the clock circuit 75 and the power supply circuit 95 for the low consumption mode. The “low consumption mode” refers to a state in which a minimum system can be started in a power generation stop state and can be shifted to various check modes.

  Referring to FIG. 7, first, a main switch ON signal is input from input unit 98 to CPU 72 (step S1), so that the clock circuit and the power supply circuit are switched to the normal mode and shifted to the normal mode (step S1). S3). Then, it waits until the power supply voltage rises, and enters a water amount check mode when it becomes stable, and the water level in the water tank 44 is detected by the water level sensor 54 (step S5).

  If the amount of water detected in step S5 is equal to or greater than a first predetermined amount (for example, 250 cc) set in advance (YES in step S7), then the water pump 60 is driven and the water in the water tank 44 is returned to the water. The solution is returned to the aqueous solution tank 18 through the pipe 58 (step S9). Thereafter, when the amount of water detected by the water level sensor 54 reaches a preset second predetermined amount (for example, 220 cc) (YES in step S11), the water pump 60 is stopped (step S13).

  Further, after step S9, even if the amount of water detected by the water level sensor 54 does not become the second predetermined amount (NO in step S11), if a certain time (for example, 1 minute) elapses (YES in step S15), step S13 Move on. Thus, by stopping the water pump 60 after a predetermined time has elapsed, for example, the amount of water detected due to an abnormality of the water level sensor 54 does not become the second predetermined amount indefinitely and power generation cannot be performed. Until the predetermined time elapses (NO in step S15), the process of step S9 is continued.

  After step S13, the auxiliary devices such as the fuel pump 20, the aqueous solution pump 26, the air pump 34, the heat exchanger cooling fan 28, the gas-liquid separator cooling fan 46, and the water pump 60 are driven as described above. Power generation is performed (step S17). Similarly, when the amount of water detected in step S5 is less than the first predetermined amount (NO in step S7), the process proceeds to step S17.

  In step S <b> 9, the water pump 60 is driven by the power of the secondary battery 102, but it may be determined that the water pump 60 is not driven because the remaining capacity of the secondary battery 102 is insufficient. In this case, in order to prevent the fuel cell system 10 from going down, the operation proceeds to power generation without driving the water pump 60. If it is not possible to shift to power generation, the fuel cell system 10 is manually connected to an external power source, and thereafter, the processes after step S9 are performed.

Next, an example of the operation of the fuel cell system 10 after the end of power generation will be described.
Referring to FIGS. 8 and 9, first, a main switch OFF signal is input from input unit 98 to CPU 72 (step S <b> 101), and the operations of various auxiliary devices are sequentially stopped to generate power by fuel cell system 10. The operation ends (step S103). Then, the clock circuit and the power supply circuit are switched to the low consumption mode and enter the low consumption mode (step S105). Thereafter, there is no input to the input unit 98 (NO in step S107), and when a fixed time (for example, 30 minutes) has elapsed (YES in step S109), the clock circuit and the power supply circuit are switched to the normal mode and shift to the normal mode. (Step S111). Until a certain time elapses (NO in step S109), external input is waited.

  After step S111, it waits until the power supply voltage rises, and when it becomes stable, it enters the water amount check mode, and the water level in the water tank 44 is detected by the water level sensor 54 (step S113). If the amount of water detected in step S113 is greater than or equal to a preset first predetermined amount (for example, 250 cc) (YES in step S115), then the remaining amount of secondary battery 102 is detected (step S116). If the secondary battery 102 still has electric power that can drive the water pump 60 (YES in step S117), the water pump 60 is driven, and the water in the water tank 44 passes through the water reflux pipe 58. Then, the solution is returned to the aqueous solution tank 18 (step S119). Thereafter, when the amount of water detected by the water level sensor 54 reaches a preset second predetermined amount (for example, 220 cc) (YES in step S121), the water pump 60 is stopped (step S123), and the process returns to step S105.

  Further, when the water pump 60 cannot be driven with the remaining amount of the secondary battery 102 detected in step S116 (in the case of NO in step S117) and when the amount of water detected in step S113 is less than the first predetermined amount (in step S115). Similarly, in the case of NO), the process returns to step S105.

  Further, after step S119, even if the amount of water detected by the water level sensor 54 does not become the second predetermined amount (NO in step S121), if a certain time (for example, 1 minute) has passed (YES in step S125), step S123 is reached. The process returns to step S105. Thus, by stopping the water pump 60 after a certain time has elapsed, for example, the amount of water detected due to an abnormality of the water level sensor 54 does not become the second predetermined amount forever, and the power of the secondary battery 102 is wasted. There is no end to it. Until the predetermined time has elapsed (NO in step S125), the process of step S119 is continued.

  If there is an input to the input unit 98 in step S107 (YES) and the input is the main switch ON (YES in step S127), the process proceeds to step S3 of the operation in FIG. On the other hand, if NO in step S127, other processing is performed (step S129), and then external input is again waited. In step S129, for example, a charging process for the secondary battery 102 is performed. In the charging process for the secondary battery 102, the fuel cell system 10 is manually connected to an external power source, and the secondary battery 102 is charged.

  The first predetermined amount and the second predetermined amount in the operations of FIGS. 7 to 9 can be arbitrarily set as long as the first predetermined amount is larger than the second predetermined amount. Further, the time from the drive to stop of the water pump 60 in the operations of FIGS. 7 to 9 and the time to enter the water amount check mode of the operations of FIGS. 8 and 9 can be arbitrarily set.

  In such a fuel cell system 10, when the amount of water in the water tank 44 detected before the start of power generation is larger than the first predetermined amount, it is discharged from the discharge port 115 by the exhaust gas accompanying the driving of the air pump 34. The water in the brazing water tank 44 is returned to the aqueous solution tank 18 before the air pump 34 is driven. Further, when the amount of water in the water tank 44 detected every predetermined time after the end of power generation is larger than the first predetermined amount, the water is discharged from the discharge port 115 by the exhaust gas accompanying the driving of the air pump 34 each time. The water in the brazing water tank 44 is returned to the aqueous solution tank 18. In other words, the amount of water in the water tank 44 is adjusted so as not to exceed the first predetermined amount every predetermined time after the end of power generation and before the start of power generation. Therefore, the water discharge from the discharge port 115 at the start of power generation is suppressed, and the water that exudes from the fuel cell 12 after power generation ends in addition to the water discharged from the fuel cell 12 before power generation ends without waste. Can be reused.

  Thus, the water in the water tank 44 can be returned to the aqueous solution tank 18 before the start of power generation, and the water in the water tank 44 can be returned to the aqueous solution tank 18 every predetermined time after the end of power generation. The water discharged from 12 can be reused.

  In particular, since it can be recirculated to the aqueous solution tank 18 every predetermined time after the end of power generation, the aqueous methanol solution S that is supplied for moisturizing the solid polymer film 12a after the end of power generation and exudes from the fuel cell 12 reaches the outlet 115. In other words, the methanol utilization rate is not reduced.

  In the fuel cell system 10, only one of the operation shown in FIG. 7 and the operation shown in FIGS. 8 and 9 may be performed.

  Further, the fuel cell system 10 can be suitably used not only for motorcycles but also for any transportation equipment such as automobiles and ships.

  The present invention can also be applied to a fuel cell system equipped with a methanol steam reformer or a fuel cell system of supplying hydrogen to a fuel cell. The present invention can also be applied to a small installation type fuel cell system.

It is an illustration figure which shows the principal part of the fuel cell system of this invention. 1 is a perspective view showing a state in which a fuel cell system is mounted on a frame of a motorcycle. It is an illustration figure which shows the principal part of a fuel cell system. It is a block diagram which shows the electric constitution of a fuel cell system. It is a front view which shows a water tank and its vicinity. It is a side view which shows a water tank and its vicinity. It is a flowchart which shows an example of operation | movement of this invention. It is a flowchart which shows the other example of operation | movement of this invention. FIG. 9 is a flowchart showing a continuation of the operation of FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell system 12 Fuel cell 12a Solid polymer membrane 12b Anode 12c Cathode 15,22,54 Water level sensor 34 Air pump 40,42 Pipe 44 Water tank 50 CO ₂ vent pipe 56 Exhaust gas pipe 58 Water recirculation pipe 70 Control circuit 72 CPU
106, 108 Introduction pipe 110, 112 Discharge pipe 114b Introduction port 115 Discharge port 200 Body frame 202 Motor

Claims (8)

A fuel cell that generates electrical energy through an electrochemical reaction;
An air pump for supplying air necessary for generating electric energy to the fuel cell;
A first tank into which liquid and exhaust gas discharged from the fuel cell are introduced;
A discharge port for discharging exhaust gas provided in the first tank and introduced into the first tank from the first tank;
A sensor for detecting the amount of liquid in the first tank;
A second tank to which the liquid in the first tank is transferred;
A liquid pump for transferring the liquid in the first tank to the second tank, and when the amount of liquid in the first tank detected by the sensor before the start of power generation is greater than a predetermined amount, before driving the air pump A fuel cell system comprising control means for executing a process of transferring the liquid in the first tank to the second tank by the liquid pump. A fuel cell that generates electrical energy through an electrochemical reaction;
An air pump for supplying air necessary for generating electric energy to the fuel cell;
A first tank into which liquid and exhaust gas discharged from the fuel cell are introduced;
A discharge port for discharging exhaust gas provided in the first tank and introduced into the first tank from the first tank;
A sensor for detecting the amount of liquid in the first tank;
A second tank to which the liquid in the first tank is transferred;
A liquid pump for transferring the liquid in the first tank to the second tank; and when the amount of liquid in the first tank detected by the sensor after power generation is stopped is larger than a predetermined amount, the liquid in the first tank is A fuel cell system comprising control means for executing a process of transferring to the second tank by the liquid pump.   The control means executes a process of transferring the liquid in the first tank to the second tank by the liquid pump when the amount of liquid in the first tank detected by the sensor after power generation is stopped is larger than a predetermined amount. The fuel cell system according to claim 1.   When the amount of liquid in the first tank detected by the sensor after power generation is stopped is greater than a predetermined amount, the control means performs processing for transferring the liquid in the first tank to the second tank by the liquid pump for a predetermined time. The fuel cell system according to claim 2 or 3, which is executed every time.   The fuel cell system according to any one of claims 1 to 4, wherein the second tank is an aqueous solution tank that stores an aqueous methanol solution to be supplied to the fuel cell.   The fuel cell system according to claim 5, wherein the fuel cell is provided below the aqueous solution tank.   The fuel cell system according to any one of claims 1 to 6, which is a direct methanol fuel cell system.   Transportation equipment using the fuel cell system according to claim 1.

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