JP2006114261A - Fuel cell system and transport equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery system and transport equipment using the same which can reduce an amount of water discharged to the outside irrespective of a surrounding temperature. <P>SOLUTION: A fuel battery system 10 arranged along a flame of a motorcycle includes a fuel battery 12. A cathode 12c in the fuel battery 12 is connected to a switchable valve 42 and to the switchable valve 42, a radiator side pipe 44 which leads water and an exhaust gas including vapor discharged from the cathode 12c to a radiator 48, and an outside pipe 46 which leads them to the outside are connected. In operation, when an mount of water in a water tank 54 exceeds a predetermined upper limit, the switchable valve 42 switches the passage of water and an exhaust gas including vapor discharged from the cathode 12c from the radiator side pipe 44 to the outside pipe 46 in response to an instruction from a CPU. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a transport device using the same, and more particularly to a fuel cell system that liquefies water vapor contained in exhaust gas 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, exhaust gas containing water vapor discharged from a fuel cell is cooled by a gas-liquid separator to liquefy the water vapor, and the obtained water is stored in a water tank. In a direct methanol fuel cell system, water stored in a water tank is used as an aqueous methanol solution. In the hydrogen fuel cell system, the water stored in the water tank is used for humidifying the fuel cell. Thus, in the fuel cell system, the use of water in the water tank is indispensable.

As such a fuel cell system, in Patent Document 1, when the amount of water in the water tank is necessary and sufficient, liquefaction of water vapor contained in the exhaust gas is reduced by reducing the cooling capacity of the gas-liquid separator (water condenser). A technique for reducing the amount of water given to the water tank while suppressing the above is disclosed.
JP 2002-280046 A

  However, in the technique of Patent Document 1, even if the cooling capacity of the gas-liquid separator is reduced when the amount of water in the water tank is necessary and sufficient, if the outside air temperature (ambient temperature) is low, The water vapor contained in the exhaust gas liquefies and the water flows into the water tank. As a result, a large amount of water may overflow from the water tank and be discharged outside the fuel cell system.

  Therefore, a main object of the present invention is to provide a fuel cell system and a transport device using the same, which can suppress the amount of water discharged to the outside regardless of the ambient temperature.

  In order to achieve the above-mentioned object, a fuel cell system according to claim 1 liquefies water vapor by cooling a fuel cell that generates electric energy by an electrochemical reaction and exhaust gas containing water vapor discharged from the fuel cell. Exhaust cooling means, water tank for storing water from exhaust cooling means, first pipe for guiding exhaust discharged from fuel cell to exhaust cooling means, second pipe for guiding exhaust discharged from fuel cell to outside And control means for controlling the amount of exhaust gas flowing into the first pipe and the second pipe.

  The fuel cell system according to claim 2 is the fuel cell system according to claim 1, wherein the control means sets the flow path of the exhaust gas discharged from the fuel cell from the first pipe to the second pipe or from the second pipe. Switching means for switching to the first pipe is included, and the amount of exhaust gas flowing into the first pipe and the second pipe is controlled by causing the switching means to perform switching operation of the exhaust flow path.

  The fuel cell system according to claim 3 is the fuel cell system according to claim 2, wherein the control unit causes the switching unit to perform the switching operation of the exhaust passage in accordance with the amount of liquid in the water tank. Features.

  The fuel cell system according to claim 4 is the fuel cell system according to any one of claims 1 to 3, wherein the second pipe includes a heat insulating member.

  The fuel cell system according to claim 5 is the fuel cell system according to any one of claims 1 to 4, further comprising an exhaust pipe connected to the water tank, wherein the second pipe is connected to the exhaust pipe. It is characterized by.

  A fuel cell system according to claim 6 is the fuel cell system according to claim 5, wherein the exhaust pipe is provided upward.

  A transportation device according to a seventh aspect is characterized by using the fuel cell system according to any one of the first to sixth aspects.

  In the fuel cell system according to the first aspect, the control means controls the amount of exhaust gas flowing into the first pipe and the second pipe. Therefore, when there is sufficient water in the water tank, the amount of exhaust gas guided to the outside through the second pipe is increased, and the amount of exhaust gas guided to the water tank through the first pipe and then to the water tank is increased. Can be reduced. For example, if there is enough water in the water tank, excessive generation of water will occur even if the ambient temperature is low if the exhaust cooling means and thus the amount of exhaust gas guided to the water tank are reduced as described above. A large amount of water does not overflow from the water tank, and the amount of water discharged to the outside can be suppressed. In this way, by suppressing the amount of water discharged to the outside, wetting of the placement location of the fuel cell system is reduced, and the aesthetic appearance of the placement location is not impaired.

  In the fuel cell system according to the second aspect, the switching unit included in the control unit switches the flow path of the exhaust gas containing the water vapor discharged from the fuel cell from the first pipe to the second pipe. As a result, when there is sufficient water in the water tank, the exhaust gas containing water vapor is guided and discharged directly to the outside without going through the exhaust cooling means and the water tank. For example, if there is enough water in the water tank, switching the flow path as described above will cause excessive water to overflow from the water tank without generating excessive water even if the ambient temperature is low. No, the amount of water discharged to the outside can be reduced.

  In the fuel cell system according to the third aspect, the control unit causes the switching unit to perform the switching operation of the exhaust passage according to the amount of liquid in the water tank. Therefore, the exhaust gas containing excess water vapor from the fuel cell can be discharged to the outside so as not to pass through the exhaust cooling means and thus the water tank while securing an appropriate amount of water in the water tank.

  In the fuel cell system according to claim 4, the second pipe includes a heat insulating member so that the temperature of the exhaust gas containing water vapor does not decrease when passing through the second pipe. Therefore, the liquefaction of water vapor contained in the exhaust from the fuel cell can be further suppressed, and the amount of water discharged to the outside can be suppressed.

  In the fuel cell system according to claim 5, the second pipe is connected to the exhaust pipe provided in the water tank. Therefore, only one exhaust outlet is required, and the fuel cell system can be easily configured.

  In the fuel cell system according to claim 6, the exhaust pipe is provided upward. As a result, the water liquefied from the water vapor contained in the exhaust gas in the exhaust pipe can flow down to the water tank and be difficult to discharge to the outside.

  In transportation equipment such as motorcycles that use fuel cell systems, water tanks with the minimum capacity required for miniaturization are used, so that water overflows from the water tanks and damages the aesthetics of road surfaces and parking spaces. Is likely to occur. Since the present invention can suppress the amount of water discharged to the outside, as described in claim 7, it is suitably used for transportation equipment such as a motorcycle.

  According to this invention, the amount of water discharged to the outside can be suppressed regardless of the ambient temperature.

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 is configured as a fuel cell stack in which a plurality of fuel cells including an electrolyte 12a and an anode (fuel electrode) 12b and a cathode (air electrode) 12c sandwiching the electrolyte 12a from both sides are connected (stacked) in series. The

  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 radiator 28 that functions as a heat exchanger, and an aqueous solution filter 30 are sequentially inserted into the aqueous solution pipe 24 from the upstream side. A cooling fan 32 for cooling the radiator 28 is disposed in the vicinity of the radiator 28. The aqueous methanol solution S in the aqueous solution tank 18 is supplied to the anode 12b by the aqueous solution pump 26, cooled as required by the radiator 28, further purified by the aqueous solution filter 30, 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 switching valve 42 as a switching means is connected to the cathode 12c, and a radiator side pipe 44 as a first pipe and an external side pipe 46 as a second pipe are connected to the switching valve 42. The switching valve 42, which is a switching means, moves the flow path of exhaust gas and water containing water vapor discharged from the cathode 12c by driving the air pump 34 from the radiator side pipe 44 to the external side pipe 46, or from the external side pipe 46 to the radiator side pipe. Switch to 44. The switching valve 42 is configured to include, for example, a butterfly valve and a solenoid that drives the butterfly valve, and switches a flow path of exhaust gas including water vapor discharged from the cathode 12c and water. Note that the switching valve 42 can distribute exhaust gas including water vapor discharged from the cathode 12c and water at a predetermined ratio and allow them to flow into the radiator-side pipe 44 and the external-side pipe 46, respectively.

  The radiator side pipe 44 connects the switching valve 42 and the radiator 48 functioning as a gas-liquid separator, and guides the exhaust gas including water vapor and water discharged from the cathode 12 c to the radiator 48. A cooling fan 50 for cooling the radiator 48 is disposed in the vicinity of the radiator 48 serving as an exhaust cooling means. The radiator 48 is connected to a water tank 54 through a pipe 52, and exhaust gas and water containing water vapor cooled by the radiator 48 is supplied to the water tank 54 through the pipe 52.

  The water tank 54 contains water from the radiator 48. A water level sensor 56 is attached to the water tank 54 to detect the water level in the water tank 54. Further, an exhaust pipe 58 is connected to the water tank 54, and a muffler 60 for silencing is attached to the exhaust pipe 58.

  Referring also to FIG. 5 and FIG. 6, the external pipe 46 is connected to the exhaust pipe 58 via a connecting pipe 61 that is fitted into the exhaust pipe 58, and exhaust and water containing water vapor discharged from the cathode 12 c. The exhaust pipe 58 is guided to the outside of the fuel cell system 10.

The aqueous solution tank 18 and the water tank 54 are connected via a CO ₂ vent pipe 62. A methanol trap 64 for separating the aqueous methanol solution S is inserted in the CO ₂ vent pipe 62. As a result, the carbon dioxide discharged from the aqueous solution tank 18 is given to the water tank 54.

  The water tank 54 is connected to the aqueous solution tank 18 through a water reflux pipe 66, and a water pump 68 is inserted into the water reflux pipe 66. The water in the water tank 54 is returned to the aqueous solution tank 18 by driving the water pump 68 when necessary according to the situation of the aqueous solution tank 18.

  In the aqueous solution pipe 24, a bypass pipe 70 is formed between the radiator 28 and the aqueous solution filter 30. Further, in the fuel cell system 10, a concentration sensor 72 for detecting the concentration of the aqueous methanol solution S is provided in the bypass pipe 70, and a temperature sensor 74 for detecting the temperature of the fuel cell 12 is attached to the fuel cell 12. An outside air temperature sensor 76 for detecting the outside air temperature is provided in the vicinity of the air pump 34.

As shown in FIG. 4, the fuel cell system 10 includes a control circuit 78.
The control circuit 78 stores a CPU 80 that performs necessary calculations and controls the operation of the fuel cell system 10, a clock circuit 82 that supplies a clock to the CPU 80, a program, data, and calculation data for controlling the operation of the fuel cell system 10. For connecting the fuel cell 12 to a memory 84 made of, for example, an EEPROM, a reset IC 86 for preventing malfunction of the fuel cell system 10, an interface circuit 88 for connecting to an external device, and a motor 202 for driving a motorcycle A voltage detection circuit 92 for detecting a voltage in the electric circuit 90, a current detection circuit 94 for detecting a current flowing through the electric circuit 90, an ON / OFF circuit 96 for opening and closing the electric circuit 90, and A voltage protection circuit 98 and an electric circuit 90 for preventing overvoltage Diode 100 kicked includes a power supply circuit 102 for supplying a predetermined voltage to the electric circuit 90.

  Detection signals from the water level sensors 15, 22, and 56 are input to the CPU 80 of the control circuit 78, and detection signals from the concentration sensor 72, the temperature sensor 74, and the outside air temperature sensor 76 are input. Further, the CPU 80 receives a detection signal from the fall switch 104 that detects the presence or absence of the fall. Further, the CPU 80 is given a signal from the input unit 106 for various settings and information input. From the input unit 106, for example, a signal that triggers the start or end of power generation is given to the CPU 80 in accordance with an ON / OFF operation to a main switch (not shown).

  Further, the CPU 80 controls accessories such as the fuel pump 20, the aqueous solution pump 26, the air pump 34, the heat exchanger cooling fan 32, the switching valve 42, the gas-liquid separator cooling fan 50, and the water pump 68. Further, the CPU 80 controls the display unit 108 for displaying various types of information and notifying various types of information to the rider of the motorcycle.

  In this embodiment, the CPU 80 and the switching valve 42 constitute a control means, and the CPU 80 contains water vapor in the switching valve 42 in accordance with a detection signal from the water level sensor 56, that is, the liquid amount (water amount) in the water tank 54. The switching operation of the exhaust and water flow paths is performed.

  The fuel cell 12 is connected in parallel with a secondary battery 110 and a storage amount detection device 112 for detecting the storage amount of the secondary battery 110. The secondary battery 110 and the charged amount detection device 112 are also connected in parallel to the motor 202. The secondary battery 110 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 80 via the interface circuit 114.

Here, the water tank 54, the exhaust pipe 58 connected to the water tank 54, and the external pipe 46 connected to the exhaust pipe 58 will be described in detail with reference to FIGS.
As shown in FIGS. 2 and 3, the water tank 54 is made of, for example, FRP, is configured to be small in size so as to correspond to the location of the body frame 200, and is configured to bulge the lower part from the upper part. . The capacity of the water tank 54 is about 500 cc.

The water tank 54 is attached so that introduction pipes 116 and 118 and discharge pipes 120 and 122 made of, for example, SUS304 or the like are fitted therethrough.
The introduction pipe 116 includes a cylindrical portion 116 a that fits into the water tank 54 from the front and slightly above the water tank 54, and a substantially trumpet-shaped expansion portion 116 b that bends downward in the water tank 54. The opening area of the introduction port 124a of the expansion part 116b is set larger than that of the inlet 124b of the cylindrical part 116a. A pipe 52 is connected to the cylindrical portion 116a.

  The discharge pipe 120 is a cylindrical pipe that fits into the water tank 54 from the back surface of the water tank 54, and is provided in the water tank 54 so that the discharge port 125 is positioned above the expanded portion 116 b of the introduction pipe 116. It is done. Thus, the expansion part 116b and the discharge pipe 120 are disposed so that the introduction port 124a and the discharge port 125 do not face each other in the water tank 54.

  As shown in FIGS. 5 and 6, an exhaust pipe 58 provided upward is connected to the discharge pipe 120. One end of the exhaust pipe 58 is connected to the water tank 54 via the discharge pipe 120. From that position, the exhaust pipe 58 is stretched in the rearward direction and in the horizontal direction, then bent in the vehicle width direction and slightly obliquely upward. Further, the exhaust gas pipe 58 is bent in a direction directly behind and extended in an obliquely upward direction with a stepwise increase in inclination, and a first inclined portion 58a and a second inclined portion 58b are provided. The connecting pipe 61 is fitted into the second inclined portion 58 b of the exhaust pipe 58, and the exhaust pipe 58 and the external pipe 46 are connected via the connecting pipe 61. By providing the exhaust pipe 58 upward, most of the water flowing into the exhaust pipe 58 through the external pipe 46 and the water liquefied from water vapor in the exhaust pipe 58 flows down to the water tank 54. Can do.

  As can be seen from FIGS. 5 and 6, the external pipe 46 is configured by covering the pipe body 46 a with a heat insulating material 46 b made of urethane or the like. Thereby, the temperature drop of the exhaust gas and water containing water vapor passing through the external pipe 46 can be suppressed, and the liquefaction of the water vapor contained in the exhaust gas can be suppressed.

The introduction pipe 118 is a cylindrical pipe that fits into the water tank 54 from the top corner of the water tank 54, and is disposed above the discharge pipe 120 in the water tank 54. A CO ₂ vent pipe 62 is connected to the introduction pipe 118.
The discharge pipe 122 is a cylindrical pipe that fits into the water tank 54 from the back and near the bottom of the water tank 54, and a water reflux pipe 66 is connected to the discharge pipe 122.

Therefore, the exhaust gas including water vapor and water from the radiator 48 are introduced into the water tank 54 from the introduction pipe 116 through the pipe 52, and the water is accommodated in the water tank 54. Carbon dioxide that has passed through the aqueous solution tank 18 and the CO ₂ vent pipe 62 in this order is introduced into the water tank 54 from the introduction pipe 118. The water in the water tank 54 flows into the water reflux pipe 66 through the discharge pipe 122. Exhaust gas containing water vapor and carbon dioxide in the water tank 54 passes through the exhaust pipe 120, the exhaust pipe 58, and the muffler 60 in order, and is exhausted to the outside. In addition, when exhaust gas and water containing water vapor are allowed to flow into the exhaust pipe 58 via the external pipe 46, most of the water in the exhaust pipe 58 flows down to the water tank 54, and the exhaust gas mainly containing water vapor becomes the muffler 60. It is discharged to the outside through.

  Further, a windproof member 126 is provided in the water tank 54. The wind-proof member 126 is made of, for example, SUS304, and includes a substantially rectangular and plate-like separator 126a and a mounting portion 126b that is bent at a substantially right angle with respect to the separator 126a. The attachment portion 126b is attached to the inner wall of the side surface of the water tank 54 so that the separator 126a is substantially horizontal, and the windproof member 126 is fixed in the water tank 54. The interior of the water tank 54 is partitioned into an upper space 128a and a lower space 128b by the separator 126a. The introduction pipes 116 and 108 and the discharge pipe 120 are provided on the upper space 128a side, and the discharge pipe 122 is provided on the lower space 128b side.

  The attachment position of the wind-proof member 126 is set to a height that allows the lower space 128b to contain water necessary and sufficient for replenishment to the aqueous solution tank 18. Further, the windbreak member 126 is not in contact with the inner wall of the water tank 54 except for the attachment portion 126b, that is, the gap 130 is formed between the three outer edges of the separator 126a and the corresponding inner wall 3 surface of the water tank 54. Member 126 is positioned.

  Further, as shown in FIG. 7, the separator 126a is provided with a plurality (here, 21) of small diameter through holes 132a and a plurality (here, 13) of large diameter through holes 132b. The small-diameter through-hole 132a faces the introduction port 124a and is concentratedly provided at the exhaust and water discharge locations including water vapor from the introduction port 124a. Preferably, the diameter of the small diameter through hole 132a is set to 4 mm, and the diameter of the large diameter through hole 132b is set to 6 mm. By providing the small-diameter through hole 132a at such a position, water can be efficiently recovered while suppressing the entry of exhaust gas into the lower space 128b.

  Furthermore, as shown in FIG. 5, a protrusion (baffle plate) 134 is provided on the inner wall of the front surface on the lower space 128b side below the separator 126a and at a position having a predetermined gap from the separator 126a. The protrusion 134 is provided so as to close the gap 130 between the inner wall on the front surface of the water tank 54 and the separator 126a when viewed from the vertical direction.

  Further, in the lower space 128b, a water level sensor 56 composed of, for example, a float sensor for detecting the water level in the water tank 54 is provided. As shown in FIG. 6, the water level sensor 56 includes a sensor main body 56a and a float portion 56b attached to the sensor main body 56a. The water level sensor 56 can detect the water level in the lower space 128b when the float 56b floats as the water level in the lower space 128b changes. In other words, the water level sensor 56 can detect the amount of liquid in the water tank 54 based on the position of the floated float 56b.

Next, an example of the operation of the fuel cell system 10 during power generation will be described.
At the start of power generation, a methanol aqueous solution S having a desired concentration stored in the aqueous solution tank 18 is sent to the fuel cell 12 by driving the aqueous solution pump 26, purified by the aqueous solution filter 30 via the radiator 28, and then 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 of the aqueous methanol solution S are electrochemically reacted to generate carbon dioxide and hydrogen ions, and the generated hydrogen ions flow into the cathode 12c through the electrolyte 12a. The hydrogen ions electrochemically react with oxygen in the air supplied to the cathode 12c to generate water (water vapor) and electric energy.
The carbon dioxide generated at the anode 12b of the fuel cell 12 passes through the pipe 40, the aqueous solution tank 18, the CO ₂ vent pipe 62 and the introduction pipe 118 in this order, and is supplied to the water tank 54. The discharge pipe 120, the exhaust pipe 58 and the muffler 60 Are discharged in order.

  A part of the water vapor generated at the cathode 12c of the fuel cell 12 is liquefied to become water, and is discharged from the cathode 12c together with the exhaust by driving the air pump 34. Other saturated water vapor components are discharged from the cathode 12c as exhaust gas in the gas state by driving the air pump 34.

  When the flow path of the exhaust gas containing water vapor discharged from the cathode 12c and the water is the radiator side pipe 44, the water vapor contained in the exhaust gas is cooled by the radiator 48 and partly liquefied by lowering the dew point. The steam liquefaction operation by the radiator 48 is performed by operating the cooling fan 50 to cool the radiator 48. Exhaust gas including water vapor and water (including water liquefied from water vapor) from the radiator 48 are supplied to the water tank 54 through the pipe 52 and the introduction pipe 116 in order.

Exhaust gas and water containing water vapor from the radiator 48 are introduced into the upper space 128a from the introduction port 124a of the introduction pipe 116 by the drive of the air pump 34 as shown by an arrow W in FIG. Occurs. Most of the exhaust gas collides with the separator 126a of the windproof member 126 and swirls in the upper space 128a, and does not flow so much into the lower space 128b. The water introduced into the upper space 128a from the introduction port 124a flows down through the plurality of small diameter through holes 132a and the plurality of large diameter through holes 132b of the separator 126a, and the gap 130 between the separator 126a and the inner wall of the water tank 54. It flows down through and is stored in the lower space 128b. Even if the water stored in the lower space 128b is picked up by the swirling flow, it collides with the protrusion 134 as shown by the arrow X in FIG. 5, so that the water does not flow back into the upper space 128a.
The water stored in the water tank 54 is appropriately returned to the aqueous solution tank 18 through the water reflux pipe 66 by driving of the water pump 68 and used as water of the aqueous methanol solution S.

  On the other hand, when the flow path of the exhaust gas and water containing water vapor discharged from the cathode 12 c is the external pipe 46, the exhaust gas and water containing water vapor flows into the exhaust pipe 58 without passing through the radiator 48. At this time, the water vapor contained in the exhaust gas is hardly liquefied by passing through the external pipe 46 of the heat insulating structure. Most of the water flowing into the exhaust pipe 58 through the external pipe 46 and the water liquefied from the steam in the exhaust pipe 58 flows down to the water tank 54, and the exhaust mainly containing the steam is discharged from the muffler 60.

  The air pump 34 drives the cathode 12c to discharge water that has moved to the cathode 12c due to water crossover, and water and carbon dioxide that are generated at the cathode 12c due to methanol crossover. The water crossover is a phenomenon in which several moles of water move to the cathode 12c as the hydrogen ions generated in 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.

Next, an example of the main operation at the time of starting the fuel cell system 10 will be described.
Referring to FIG. 8, first, when a main switch (not shown) is turned on and a signal of main switch ON is input to CPU 80 (step S1), it waits until the power supply voltage rises, and when it becomes stable, The secondary battery remaining capacity is detected by 112 (step S3). It is determined whether or not the water pump 68 can be driven based on the detected secondary battery remaining capacity (step S5).

  If the secondary battery remaining capacity can supply the power required for power generation (auxiliary drive power), it is determined that the water pump 68 can be driven (YES in step S5), and the liquid level check mode is entered. The amount of liquid (water amount) in the water tank 54 is detected by the sensor 56 (step S7).

  If the amount of liquid detected in step S7 is not less than a first predetermined amount (for example, 250 cc) set in advance (YES in step S9), the water pump 68 is driven by the electric power of the secondary battery 110, and the water tank 54 Is returned to the aqueous solution tank 18 through the water reflux pipe 66 (step S11). Thereafter, when the amount of liquid detected by the water level sensor 56 is equal to or less than a second predetermined amount (for example, 220 cc) set in advance (YES in step S13), the water pump 68 is stopped (step S15).

  In step S13, even if the liquid level detected by the water level sensor 56 is not less than or equal to the second predetermined amount (NO in step S13), if a certain time (for example, 1 minute) has elapsed (YES in step S17), step S15 is performed. Proceed to In this way, by stopping the water pump 68 after a certain time has elapsed, the amount of liquid detected due to, for example, an abnormality of the water level sensor 56 does not become the second predetermined amount indefinitely and power generation cannot be performed. Until the predetermined time elapses (NO in step S17), the process of step S11 is continued.

  After step S15, the auxiliary devices such as the fuel pump 20, the aqueous solution pump 26, the air pump 34, the heat exchanger cooling fan 32, the gas-liquid separator cooling fan 50, and the water pump 68 are driven to generate power as described above. Performed (step S19). If the amount of liquid in the water tank 54 is less than the first predetermined amount in step S9 (NO in step S9), the process proceeds to step S19.

  If the remaining capacity of the secondary battery is so small that the power necessary for power generation (power for driving auxiliary equipment) cannot be supplied, it is determined that the water pump 68 cannot be driven (NO in step S5). In this case, in order to prevent the fuel cell system 10 from going down, another process is performed without driving the water pump 68 (step S21), and the process proceeds to step S19 to start power generation.

Next, an example of main operations during operation (power generation) of the fuel cell system 10 will be described with reference to FIG.
When the operation of the fuel cell system 10 is started, the liquid level of the aqueous methanol solution S in the aqueous solution tank 18 is detected by the water level sensor 22 (step S101). If the detected liquid amount in the aqueous solution tank 18 is a predetermined amount (for example, 1000 cc) or less (YES in step S103), the water pump 68 is driven by an instruction from the CPU 80, and the water in the water tank 54 is supplied to the water reflux pipe. 66 is returned to the aqueous solution tank 18 (step S105).

  After step S105, the water level sensor 56 detects the amount of liquid in the water tank 54 (step S107), and if the amount of liquid in the water tank 54 is less than a lower limit (for example, 100 cc) (YES in step S109). The water pump 68 is stopped (step S111). In step S109, even if the liquid level detected by the water level sensor 56 is not less than the lower limit (NO in step S109), if a certain time (for example, 1 minute) has passed (YES in step S113), the process proceeds to step S111. Until the predetermined time has elapsed (NO in step S113), the processing in step S105 is continued.

  If a certain time (for example, 3 minutes) has elapsed from step S101 after step S111 (YES in step S115), the liquid level in the water tank 54 is detected by the water level sensor 56 (step S117). Until a predetermined time has elapsed (NO in step S115), the process waits. In step S103, if the amount of liquid in the aqueous solution tank 18 exceeds the predetermined amount (NO in step S103), the process proceeds to step S115.

  If the amount of liquid in the water tank 54 detected in step S117 exceeds an upper limit value (for example, 400 cc) (YES in step S119), and the flow path of exhaust discharged from the cathode 12c is the radiator side pipe 44 (step When S121 is YES), the switching valve 42 performs the flow path switching operation according to the instruction of the CPU 80. (Step S123).

  In step S123, the switching valve 42 switches the flow path of exhaust gas and water containing water vapor discharged from the cathode 12c from the radiator side pipe 44 to the external side pipe 46. As a result, the exhaust gas containing water vapor and water discharged from the cathode 12c flow into the exhaust pipe 58, and most of the water in the exhaust pipe 58 flows down to the water tank 54, and the exhaust gas containing a small amount of water and water vapor. Are discharged from the muffler 60.

  Then, after step S123, the cooling fan 50 is stopped according to the instruction from the CPU 80 (step S125), and the process returns to step S101. When the exhaust gas including water vapor discharged from the cathode 12c and water do not pass through the radiator 48, the temperature of the radiator 48 naturally decreases. Therefore, by stopping the cooling fan 50, the power consumption of the fuel cell system 10 is reduced. Energy efficiency can be improved. In step S121, if the flow path of the exhaust discharged from the cathode 12c is the external side pipe 46 (NO in step S121), the process returns to step S101.

  On the other hand, if the amount of liquid in the water tank 54 detected in step S117 is less than or equal to the upper limit (step S119 is NO), and the flow path of the exhaust discharged from the cathode 12c is the external pipe 46 (step S127). Is YES), the driving of the cooling fan 50 is started (step S129). After step S129, the switching valve 42 performs a flow path switching operation in accordance with an instruction from the CPU 80. (Step S131).

  In step S131, the switching valve 42 switches the flow path of the exhaust gas containing water vapor and water discharged from the cathode 12c from the external pipe 46 to the radiator side pipe 44. As a result, the exhaust gas including water vapor discharged from the cathode 12 and water are supplied to the radiator 48 and the water tank 54.

  Then, after step S131, the process returns to step S101. In step S127, if the flow path of the exhaust discharged from the cathode 12c is the radiator side pipe 44 (NO in step S127), the process returns to step S101.

  In the above-described embodiment, the case where the switching valve 42 switches the flow path of the exhaust gas and the water from the cathode 12c to either the radiator side pipe 44 or the external side pipe 46 has been described. The control of the amount of exhaust gas and water flowing into 46 is not limited to this. For example, the switching valve 42 may distribute the exhaust gas and water from the cathode 12c at a predetermined ratio so as to flow into the radiator side pipe 44 and the external side pipe 46, respectively.

  In such a fuel cell system 10, when the amount of liquid in the water tank 54 exceeds the upper limit during operation (power generation), exhaust and water flow paths including water vapor discharged from the cathode 12 c by the switching valve 42. Is switched from the radiator side pipe 44 to the external side pipe 46. That is, while ensuring an appropriate amount of water in the water tank 54, the exhaust gas including water vapor discharged from the cathode 12 c and the water are guided to the exhaust pipe 58 so as not to pass through the radiator 48 and thus the water tank 54. Accordingly, water does not overflow from the water tank 54 even when the ambient temperature is low. Further, the exhaust gas including water vapor and water discharged from the cathode 12c do not pass through the radiator 48, in other words, bypass the radiator 48 and are guided to the exhaust pipe 58 by the external pipe 46 having a heat insulating structure. Thereby, the liquefaction of water vapor contained in the exhaust gas discharged from the cathode 12c can be suppressed, most of the water vapor can be discharged to the outside as a gas, and the amount of water discharged to the outside can be suppressed. Further, by providing the exhaust pipe 58 upward, most of the water in the exhaust pipe 58 can flow down to the water tank 54, and the amount of water discharged to the outside can be suppressed. In this way, by suppressing the amount of water discharged to the outside, wetting of the parking space of the motorcycle is reduced and the aesthetic appearance is not impaired.

  Further, by connecting the external pipe 46 to the exhaust pipe 58, one muffler 60 may be provided, and the system can be configured easily.

  The means for detecting the amount of liquid in the water tank 54 is not limited to the means for detecting based on the water level in the water tank 54, and any other means can be applied.

  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 reformer-mounted fuel cell system and a fuel cell system that supplies hydrogen to the 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 which concerns on 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 side view which shows a water tank and its vicinity. It is a cross-sectional solution figure which shows a water tank and its vicinity. It is AA sectional drawing in FIG. It is a flowchart which shows an example of main operation | movement at the time of starting of the fuel cell system concerning this invention. It is a flowchart which shows an example of main operation | movement at the time of operation | movement of the fuel cell system which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell system 12 Fuel cell 12c Cathode 15,22,56 Water level sensor 28,48 Radiator 32,50 Cooling fan 42 Switching valve 44 Radiator side pipe 46 External side pipe 46a Pipe main body 46b Thermal insulation material 54 Water tank 58 Exhaust pipe 60 Muffler 80 CPU
200 body frame

Claims (7)

A fuel cell that generates electrical energy through an electrochemical reaction;
An exhaust cooling means for liquefying the water vapor by cooling the exhaust gas containing water vapor discharged from the fuel cell;
A water tank for containing water from the exhaust cooling means,
A first pipe for guiding the exhaust discharged from the fuel cell to the exhaust cooling means;
A fuel cell system, comprising: a second pipe that guides the exhaust discharged from the fuel cell to the outside; and a control unit that controls an amount of the exhaust flowing into the first pipe and the second pipe.   The control means includes switching means for switching a flow path of the exhaust discharged from the fuel cell from the first pipe to the second pipe or from the second pipe to the first pipe, and the switching means includes the switching means. 2. The fuel cell system according to claim 1, wherein an amount of the exhaust gas flowing into the first pipe and the second pipe is controlled by performing an operation of switching an exhaust passage. 3.   3. The fuel cell system according to claim 2, wherein the control unit causes the switching unit to perform a switching operation of the exhaust passage in accordance with an amount of liquid in the water tank.   The fuel cell system according to any one of claims 1 to 3, wherein the second pipe includes a heat insulating member.   The fuel cell system according to any one of claims 1 to 4, further comprising an exhaust pipe connected to the water tank, wherein the second pipe is connected to the exhaust pipe.   The fuel cell system according to claim 5, wherein the exhaust pipe is provided upward. Transportation equipment using the fuel cell system according to claim 1.

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