JP4863689B2 - Fuel cell system and concentration adjustment method thereof - Google Patents

Description

  The present invention relates to a fuel cell system and a concentration adjustment method thereof, and more particularly to a fuel cell system for controlling the concentration of a fuel aqueous solution and a concentration adjustment method thereof.

An example of a technique for adjusting the fuel concentration is disclosed in Patent Document 1.
In Patent Document 1, the component of the gas discharged from the fuel cell and the amount of power generated by the fuel cell are measured without directly measuring the fuel concentration in the dilution tank, and the fuel to be supplied to the dilution tank based on the results thereof, and A technique for controlling the amount of water and adjusting the concentration is disclosed.
JP 2005-26215 A

However, with the technique described in Patent Document 1, it is considered that the concentration cannot be adjusted accurately when an oxidant deficiency process (air stave process) is performed.
In other words, the oxidant deficiency process is a process in which the supply of the oxidant to the cathode of the fuel cell is temporarily stopped or the supply amount of the oxidant to the cathode is temporarily reduced to bring the cathode into an oxidant deficiency state. However, there is a problem that the concentration cannot be adjusted accurately immediately after the execution of this process, but Patent Document 1 does not disclose or suggest the concentration adjustment when the oxidizing agent deficiency process is executed.

  Therefore, a main object of the present invention is to provide a fuel cell system and its concentration adjusting method capable of accurately adjusting the concentration of the aqueous fuel solution even when the oxidant deficiency treatment is executed.

  In order to achieve the above object, the fuel cell system according to claim 1 is a fuel cell that generates electric energy by an electrochemical reaction, and electrochemical characteristics of an aqueous fuel solution used for generating electric energy in the fuel cell. A first concentration detecting means for detecting concentration information corresponding to the concentration of the aqueous fuel solution using a second concentration detecting means for detecting concentration information corresponding to the concentration of the aqueous fuel solution by a method different from the first concentration detecting means; Storage means for storing concentration information detected before the oxidant deficiency treatment by the first concentration detection means, and concentration adjustment based on the concentration information detected by the second concentration detection means after the oxidant deficiency processing, The concentration is adjusted to be higher than the target concentration, and the concentration information detected after the oxidant deficiency treatment by the first concentration detection means is stored in the storage means. When the it is determined that with higher concentration than the concentration information comprises concentration adjusting means for adjusting the concentration of the fuel aqueous solution based on the concentration information detected by the first density detecting means.

  The fuel cell system according to claim 2 is the fuel cell system according to claim 1, wherein the second concentration detecting means detects concentration information of the aqueous fuel solution based on the current from the fuel cell.

  A motorcycle according to a third aspect includes the fuel cell system according to the first or second aspect.

  A transportation device according to a fourth aspect includes the fuel cell system according to the first or second aspect.

  The fuel cell system concentration adjusting method according to claim 5 is a fuel cell that generates electric energy by an electrochemical reaction, and a fuel that uses an electrochemical characteristic of an aqueous fuel solution used for generating electric energy in the fuel cell. First concentration detecting means for detecting concentration information corresponding to the concentration of the aqueous solution, second concentration detecting means for detecting concentration information corresponding to the concentration of the aqueous fuel solution by a method different from the first concentration detecting means, and storing the concentration information A fuel cell system concentration adjustment method comprising a storage means capable of storing concentration information detected by the first concentration detection means before the oxidant deficiency process in the storage means, after the oxidant deficiency process, Adjusting the concentration of the aqueous fuel solution to be higher than the target concentration based on the concentration information detected by the concentration detecting means; and a first concentration When the concentration information detected after the oxidant deficiency treatment by the output means indicates a higher concentration than the concentration information stored in the storage means, the concentration of the aqueous fuel solution is determined based on the concentration information detected by the first concentration detection means. Adjusting.

  Here, the “target concentration” refers to a target concentration of the aqueous fuel solution after the oxidant deficiency treatment.

  In the fuel cell system according to the first aspect, the concentration information detected by the first concentration detection means before the oxidant deficiency treatment is stored in the storage means. Then, the concentration of the aqueous fuel solution (fuel concentration) is adjusted to be higher than the target concentration based on the concentration information detected after the oxidant deficiency processing by the second concentration detection unit, and the oxidant deficiency processing is performed by the first concentration detection unit. When the concentration information detected later indicates a higher concentration than the concentration information stored in the storage means, the concentration of the aqueous fuel solution is adjusted based on the concentration information detected by the first concentration detection means. That is, it is known that even if the concentration information is detected immediately after the oxidant deficiency treatment by the first concentration detection means that detects the concentration information using the electrochemical characteristics of the aqueous fuel solution, the detection result is not accurate. Therefore, in order to avoid this, the concentration information of the first concentration detection means is temporarily not used immediately after the oxidant deficiency treatment, and the concentration of the aqueous fuel solution is adjusted based on the concentration information by the second concentration detection means. In addition, the concentration of the aqueous fuel solution is adjusted to be higher than the target concentration. Accordingly, it is possible to maintain high detection accuracy of the fuel concentration in the fuel cell system that performs the oxidant deficiency process, and to quickly return the detection accuracy of the first concentration detection means to normal after the oxidant deficiency process and detect the second concentration. It is possible to quickly switch from the means to the first concentration detecting means. As a result, the fuel concentration can be accurately adjusted even when the oxidant deficiency treatment is performed. The same applies to the fuel cell system concentration adjustment method according to claim 5.

  The concentration detection accuracy of the first concentration detection means is reduced immediately after the execution of the oxidant deficiency process, but in the fuel cell system according to claim 2, the fuel based on the current from the fuel cell is immediately after the execution of the oxidant deficiency process. Since the concentration information of the aqueous solution can be acquired, it is possible to suppress a decrease in concentration detection accuracy.

  Since the motorcycle including the fuel cell system as described in claim 3 and claim 4 and thus the transportation equipment is subjected to an oxidant deficiency treatment as necessary in order to improve power generation efficiency, the present invention is preferably used. It is done.

  According to the present invention, the concentration of the aqueous fuel solution can be accurately adjusted in the fuel cell system that executes the oxidant deficiency treatment.

  Embodiments of the present invention will be described below with reference to the drawings. Here, a case where the fuel cell system 100 of the present invention is mounted on a motorcycle 10 which is an example of a transportation device will be described.

  First, the motorcycle 10 will be described. Left and right, front and rear, and top and bottom in the embodiment of the present invention mean left and right, front and back, and top and bottom, based on a state where the driver is seated on the seat of the motorcycle 10 toward the handle 24 thereof.

  1 to 7, the motorcycle 10 includes a vehicle body 11, and the vehicle body 11 has a vehicle body frame 12. The vehicle body frame 12 includes a head pipe 14, a front frame 16 having an I-shaped longitudinal section extending obliquely downward from the head pipe 14, and a rear frame connected to a rear end portion of the front frame 16 and rising obliquely upward rearward. 18 and a seat rail 20 attached to the upper end of the rear frame 18. The rear end portion of the front frame 16 is connected to a position slightly closer to the lower end portion than the center portion of the rear frame 18, and the front frame 16 and the rear frame 18 as a whole have a substantially Y shape in side view.

  The front frame 16 has a plate-like member 16a having a width in the up-down direction, extending obliquely downward to the rear and orthogonal to the left-right direction, and formed at the upper and lower edges of the plate-like member 16a, respectively, and to the rear. Flange portions 16b and 16c extending obliquely downward and having a width in the left-right direction, reinforcing ribs 16d projecting on both surfaces of the plate-like member 16a, and the rear frame 18 are connected to each other by, for example, bolts provided at the rear end portion. Connecting portion 16e. The reinforcing rib 16d partitions both surfaces of the plate-like member 16a together with the flange portions 16b and 16c to form a storage space for storing components of the fuel cell system 100 described later.

  On the other hand, the rear frame 18 extends rearward and obliquely upward, has a width in the front-rear direction, and is disposed so as to sandwich the connecting portion 16e of the front frame 16, and the plate-shaped members 18a and 18b. And a plate-like member (not shown) for connecting the two.

  As shown in FIG. 1, a steering shaft 22 for changing the vehicle body direction is rotatably inserted into the head pipe 14. A handle support portion 26 to which a handle 24 is fixed is attached to the upper end of the steering shaft 22, and grips 28 are attached to both ends of the handle 24. The right grip 28 constitutes a rotatable throttle grip.

  A display operation unit 30 is disposed in front of the handle 24 of the handle support unit 26. The display operation unit 30 includes a meter 30a for measuring and displaying various data of an electric motor 60 (described later), a display unit 30b configured by, for example, a liquid crystal display for providing various information such as a running state, and various information input. The input unit 30c and the like are integrated. A headlamp 32 is fixed below the display operation section 30 in the handle support section 26, and flasher lamps 34 are provided on both the left and right sides of the headlamp 32.

  A pair of left and right front forks 36 are attached to the lower end of the steering shaft 22, and a front wheel 38 is attached to the lower end of each front fork 36 via a front axle 40. The front wheel 38 is rotatably supported by the front axle 40 while being buffered and suspended by the front fork 36.

  On the other hand, a frame-like seat rail 20 is attached to the rear end portion of the rear frame 18. The seat rail 20 is fixed to the upper end portion of the rear frame 18 by welding, for example, and is disposed substantially in the front-rear direction. A seat (not shown) is provided on the seat rail 20 so as to be freely opened and closed. A mounting bracket 42 is fixed to the rear end portion of the seat rail 20, and a tail lamp 44 and a pair of left and right flasher lamps 46 are mounted on the mounting bracket 42, respectively.

  A swing arm (rear arm) 48 is swingably supported at the lower end portion of the rear frame 18 via a pivot shaft 50, and an electric motor 60 (described later) is provided at a rear end portion 48a of the swing arm 48. A rear wheel 52, which is a drive wheel, is rotatably supported, and the swing arm 48 and the rear wheel 52 are buffered and suspended from the rear frame 18 by a rear cushion (not shown).

  Further, a footrest mounting bar 54 is fixed to the front side of the lower end portion of the rear frame 18 so as to protrude from the rear frame 18 in the left-right direction, and a footrest (not shown) is mounted on the footrest mounting bar 54. Behind the footrest mounting bar 54, a main stand 56 is rotatably supported by a swing arm 48, and the main stand 56 is urged toward the closing side by a return spring 58.

  In this embodiment, the swing arm 48 is connected to the rear wheel 52, for example, an axial gap type electric motor 60 for rotating the rear wheel 52, and a drive unit 62 electrically connected to the electric motor 60. And built-in. The drive unit 62 includes a controller 64 for controlling the rotational drive of the electric motor 60.

  A fuel cell system 100 is attached to the vehicle body 11 of the motorcycle 10 along the vehicle body frame 12. The fuel cell system 100 generates electrical energy for driving the electric motor 60 and other components.

Hereinafter, the fuel cell system 100 will be described.
The fuel cell system 100 is a direct methanol fuel cell system that directly uses methanol (aqueous methanol solution) for power generation without reforming.

  The fuel cell system 100 includes a fuel cell stack (hereinafter simply referred to as a cell stack) 102 disposed below the front frame 16.

  As shown in FIGS. 8 and 9, the cell stack 102 sandwiches a separator 106 with a fuel cell (fuel cell) 104 that can generate electric energy by an electrochemical reaction between hydrogen ions based on methanol and oxygen. A plurality of layers are stacked. Each fuel cell 104 constituting the cell stack 102 includes an electrolyte (electrolyte membrane) 104a composed of a solid polymer membrane and the like, an anode (fuel electrode) 104b and a cathode (air electrode) facing each other across the electrolyte 104a. 104c. Each of the anode 104b and the cathode 104c includes a platinum catalyst layer provided on the electrolyte 104a side.

  As shown in FIG. 4 and the like, the cell stack 102 is placed on a skid 108, and the skid 108 is supported by a stay stack 110 that is suspended from a flange portion 16 c of the front frame 16.

  As shown in FIG. 6, an aqueous solution radiator 112 and a gas-liquid separation radiator 114 are disposed below the front frame 16 and above the cell stack 102. The radiators 112 and 114 are integrally formed, and have a plurality of plate-like fins (not shown) whose front surfaces are disposed slightly forward of the vehicle and are orthogonal to the front surfaces. Such radiators 112 and 114 can sufficiently receive wind during traveling.

  As shown in FIG. 6 and the like, the radiator 112 includes a radiator pipe 116 that is formed to pivot. The radiator pipe 116 is formed as a single continuous pipe from the inlet 118a (see FIG. 5) to the outlet 118b (see FIG. 3) by welding a straight pipe made of stainless steel or the like and a U-shaped joint pipe. Is formed. A radiator cooling fan 120 is provided on the back side of the radiator 112 so as to face the radiator pipe 116.

  Similarly, the radiator 114 includes two radiator pipes 122 formed to meander. Each radiator pipe 122 is a single continuous pipe from the inlet 124a (see FIG. 3) to the outlet 124b (see FIG. 3) by welding a straight pipe made of stainless steel or the like and a U-shaped joint pipe. Is formed. A radiator cooling fan 126 is provided on the back surface side of the radiator 114 so as to face the radiator pipe 122.

  1 to 7 and mainly referring to FIG. 3, a fuel tank 128, an aqueous solution tank 130, and a water tank 132 are arranged in order from the top on the rear side of the connecting portion 16 e of the front frame 16. The fuel tank 128, the aqueous solution tank 130, and the water tank 132 are obtained by, for example, PE (polyethylene) blow molding.

  The fuel tank 128 is disposed below the seat rail 20 and is attached to the rear end portion of the seat rail 20. The fuel tank 128 contains methanol fuel (high-concentration aqueous methanol solution) with a high concentration (for example, containing about 50 wt% of methanol) that becomes a fuel for the electrochemical reaction of the cell stack 102. The fuel tank 128 has a lid 128a on its upper surface, and the lid 128a is removed to supply methanol fuel.

  The aqueous solution tank 130 is provided below the fuel tank 128 and attached to the rear frame 18. The aqueous solution tank 130 contains an aqueous methanol solution obtained by diluting the methanol fuel from the fuel tank 128 to a concentration suitable for the electrochemical reaction of the cell stack 102 (for example, containing about 3 wt% of methanol). That is, the aqueous solution tank 130 contains an aqueous methanol solution to be sent out toward the cell stack 102 by an aqueous solution pump 146 (described later).

  A level sensor 129 is attached to the fuel tank 128 to detect the level of the methanol fuel level in the fuel tank 128. A level sensor 131 is attached to the aqueous solution tank 130 to detect the level of the aqueous methanol solution in the aqueous solution tank 130. By detecting the liquid level height with the level sensors 129 and 131, the amount of liquid in the tank can be detected. The liquid level in the aqueous solution tank 130 is controlled, for example, within a range indicated by A in FIG.

  The water tank 132 is disposed between the plate-like members 18 a and 18 b of the rear frame 18 and on the rear side of the cell stack 102. A level sensor 133 is attached to the water tank 132 and the height of the water surface in the water tank 132 is detected.

  A secondary battery 134 is provided on the front side of the fuel tank 128 and on the upper side of the flange portion 16 b of the front frame 16. The secondary battery 134 is disposed on the upper surface of a plate-like member (not shown) of the rear frame 18. The secondary battery 134 stores the electrical energy generated in the cell stack 102 and supplies the electrical energy to the corresponding electrical component in accordance with a command from a controller 156 (described later). For example, the secondary battery 134 supplies electric energy to the auxiliary machines and the drive unit 62.

  A fuel pump 136 and a detection valve 138 are disposed above the secondary battery 134 and below the seat rail 20. A catch tank 140 is disposed above the aqueous solution tank 130.

  The catch tank 140 is provided with a lid 140a on the upper surface thereof. For example, in a state where the fuel cell system 100 has never been activated (the aqueous solution tank 130 is empty), the aqueous methanol solution is supplied by removing the lid 140a. The catch tank 140 is obtained by PE (polyethylene) blow molding, for example.

  An air filter 142 for removing foreign substances such as dust contained in the gas is disposed in a space surrounded by the front frame 16, the cell stack 102, and the radiators 112 and 114. On the side, an aqueous solution filter 144 is arranged.

  As shown in FIG. 4, an aqueous solution pump 146 and an air pump 148 are stored in the storage space on the left side of the front frame 16. An air chamber 150 is disposed on the left side of the air pump 148. By driving the aqueous solution pump 146, an aqueous methanol solution is sent out toward the cell stack 102.

  Further, as shown in FIG. 5, a main switch 152, a DC-DC converter 154, a controller 156, a rust prevention valve 158, and a water pump 160 are arranged in order from the front in the storage space on the right side of the front frame 16. The main switch 152 is provided so as to penetrate the storage space of the front frame 16 from the right side to the left side. A horn 162 is provided on the front surface of the cell stack 102. The DC-DC converter 154 converts the voltage from 24V to 12V, and the fans 120 and 126 are driven by the converted 12V voltage.

The piping of the fuel cell system 100 arranged in this way will be described with reference to FIGS. 4 to 7 and FIG.
The fuel tank 128 and the fuel pump 136 are connected by a pipe P1, and the fuel pump 136 and the aqueous solution tank 130 are connected by a pipe P2. The pipe P1 connects the lower left end of the fuel tank 128 and the lower left end of the fuel pump 136, and the pipe P2 connects the lower left end of the fuel pump 136 and the lower left end of the aqueous solution tank 130. By driving the fuel pump 136, the methanol fuel in the fuel tank 128 is supplied to the aqueous solution tank 130 through the pipes P1 and P2.

  The aqueous solution tank 130 and the aqueous solution pump 146 are communicated by a pipe P3, the aqueous solution pump 146 and the aqueous solution filter 144 are communicated by a pipe P4, and the aqueous solution filter 144 and the cell stack 102 are communicated by a pipe P5. The pipe P3 connects the lower left side corner of the aqueous solution tank 130 and the rear portion of the aqueous solution pump 146, the pipe P4 connects the rear portion of the aqueous solution pump 146 and the left side surface of the aqueous solution filter 144, and the pipe P5 connects the aqueous solution filter 144. The right side is connected to the anode inlet I1 located at the lower right corner of the front surface of the cell stack 102. By driving the aqueous solution pump 146, the aqueous methanol solution from the aqueous solution tank 130 is sent from the pipe P3 side to the pipe P4 side, and after impurities are removed by the aqueous solution filter 144, the aqueous solution pump 146 enters the cell stack 102 via the pipe P5. Given. In this embodiment, pipes P4 and P5 constitute pipes for guiding the aqueous methanol solution sent out by the aqueous solution pump 146 to each fuel cell 104 of the cell stack 102.

  The cell stack 102 and the aqueous solution radiator 112 are connected by a pipe P6, and the radiator 112 and the aqueous solution tank 130 are connected by a pipe P7. The pipe P6 connects the anode outlet I2 located at the upper left corner of the rear surface of the cell stack 102 and the inlet 118a (see FIG. 5) of the radiator pipe 116 drawn from the lower right end of the radiator 112, and the pipe P7 is connected to the radiator 112. The outlet 118b of the radiator pipe 116 (see FIG. 3) drawn from a position slightly closer to the center from the lower left end of the lower surface of the aqueous solution tank 130 is connected to the upper left corner of the aqueous solution tank 130. The unreacted aqueous methanol solution and carbon dioxide discharged from the cell stack 102 are supplied to the radiator 112 via the pipe P6, the temperature is lowered, and returned to the aqueous solution tank 130 via the pipe P7. As a result, the temperature of the aqueous methanol solution in the aqueous solution tank 130 can be lowered.

  The pipes P1 to P7 described above mainly serve as fuel flow paths.

  Further, the air filter 142 and the air chamber 150 are communicated by a pipe P8, the air chamber 150 and the air pump 148 are communicated by a pipe P9, and the air pump 148 and the rust prevention valve 158 are connected by a pipe P10 and are used for rust prevention. The valve 158 and the cell stack 102 are connected by a pipe P11. The pipe P8 connects the rear part of the air filter 142 and a position slightly ahead of the center part of the air chamber 150, and the pipe P9 connects the lower side of the center part of the air chamber 150 and the rear part of the air pump 148. P10 connects the air pump 148 located on the left side of the plate member 16a of the front frame 16 and the rust prevention valve 158 located on the right side of the plate member 16a, and the pipe P11 is connected to the rust prevention valve 158 and the cell stack 102. To the cathode inlet I3 located at the upper right end of the rear surface. When the fuel cell system 100 is operated, the rust prevention valve 158 is opened, and the air pump 148 is driven in this state, whereby oxygen-containing air is sucked from the outside. The sucked air is purified by the air filter 142 and then flows into the air pump 148 through the pipe P8, the air chamber 150 and the pipe P9, and further, the cell is passed through the pipe P10, the rust prevention valve 158 and the pipe P11. Is provided to the stack 102. The rust prevention valve 158 is closed when the fuel cell system 100 is stopped, and prevents the backflow of water vapor to the air pump 148 and prevents the air pump 148 from rusting.

  The cell stack 102 and the radiator 114 for gas-liquid separation are communicated with each other by two pipes P12. The radiator 114 and the water tank 132 are communicated by two pipes P13, and the water tank 132 is connected to a pipe (exhaust pipe) P14. Is provided. Each pipe P12 connects a cathode outlet I4 located at the lower left corner of the front surface of the cell stack 102 and an inlet 124a (see FIG. 3) of each radiator pipe 122 drawn from the lower left end of the radiator 114. The outlet 124b (see FIG. 3) of each radiator pipe 122 drawn from a position slightly on the left side of the lower surface of the radiator 114 is connected to the front upper part of the water tank 132, and the pipe P14 is an upper rear part of the water tank 132. It is formed in a U shape so that it rises once and then descends. Exhaust gas containing water (water and water vapor) and carbon dioxide discharged from the cathode outlet I4 of the cell stack 102 is given to the radiator 114 via the pipe P12, and the water vapor is liquefied. Exhaust gas from the radiator 114 is supplied to the water tank 132 together with water through the pipe P13, and is discharged to the outside through the pipe P14.

  The pipes P8 to P14 described above mainly serve as an exhaust passage.

  Further, the water tank 132 and the water pump 160 are communicated by a pipe P15, and the water pump 160 and the aqueous solution tank 130 are communicated by a pipe P16. The pipe P15 connects the lower right side of the water tank 132 and the central part of the water pump 160, and the pipe P16 connects the central part of the water pump 160 and the upper left corner of the aqueous solution tank 130. By driving the water pump 160, the water in the water tank 132 is returned to the aqueous solution tank 130 via the pipes P15 and P16.

  The pipes P15 and P16 described above serve as water flow paths.

  In addition, a pipe P17 is connected to the pipe P4 so that a part of the methanol aqueous solution sent out by the aqueous solution pump 146 and flowing through the pipe P4 flows. As shown in FIG. 4, the ultrasonic sensor 164 for detecting the methanol concentration in the pipe P17 is attached to the pipe P17. The ultrasonic sensor 164 detects the methanol concentration of the aqueous methanol solution in the pipe P17 by utilizing the fact that the ultrasonic wave propagation speed changes in accordance with the methanol concentration of the methanol aqueous solution that has flowed in (ratio of methanol in the aqueous methanol solution). Used for.

  As shown in FIG. 4, the ultrasonic sensor 164 includes a transmission unit 164a that generates ultrasonic waves and a reception unit 164b that detects ultrasonic waves. Transmitter 164a is inserted in pipe P4. The starting end of the pipe P17 is connected to the branch port 165 of the transmitter 164a, and an aqueous methanol solution is introduced into the pipe P17 via the branch port 165. The receiving unit 164b is connected to the end of the pipe P17 and disposed on the left side surface of the secondary battery 134. In the ultrasonic sensor 164, the time from the generation of ultrasonic waves at the transmission unit 164a to the reception of the ultrasonic waves at the reception unit 164b after the transmission unit 164a generates ultrasonic waves, the reception unit 164b receives ultrasonic waves. Is detected, and the propagation speed is converted into a voltage value to obtain physical concentration information. The controller 156 detects the methanol concentration of the aqueous methanol solution in the pipe P17 based on the concentration information.

  The receiving unit 164b and the detection valve 138 are communicated with each other by a pipe P18. Further, the detection valve 138 and the aqueous solution tank 130 are communicated with each other by a pipe P19. The pipe P18 connects the upper surface of the receiving unit 164b and the left side surface of the detection valve 138, and the pipe P19 connects the right side surface of the detection valve 138 and the upper surface of the aqueous solution tank 130.

  The pipes P17 to P19 described above mainly serve as a concentration detection flow path.

  Further, the aqueous solution tank 130 and the catch tank 140 are communicated by a pipe P20, the catch tank 140 and the aqueous solution tank 130 are communicated by a pipe P21, and the catch tank 140 and the air chamber 150 are communicated by a pipe P22. The pipe P20 connects the upper left corner of the aqueous solution tank 130 and the upper left corner of the catch tank 140, and the pipe P21 connects the lower end of the catch tank 140 and the lower left corner of the aqueous solution tank 130. The pipe P22 connects a position near the upper left side of the catch tank 140 and the upper end surface of the air chamber 150. The gas (mainly carbon dioxide, vaporized methanol and water vapor) in the aqueous solution tank 130 is given to the catch tank 140 via the pipe P20. The vaporized methanol and water vapor are cooled and liquefied in the catch tank 140, and then returned to the aqueous solution tank 130 through the pipe P21. The gas (carbon dioxide, unliquefied methanol and water vapor) in the catch tank 140 is supplied to the air chamber 150 via the pipe P22.

  The pipes P20 to P22 described above mainly serve as fuel processing channels.

  As shown in FIG. 10, the receiver 164 b of the ultrasonic sensor 164 is provided with a first temperature sensor 166 for detecting the temperature of the aqueous methanol solution that passes through the ultrasonic sensor 164. Further, in the vicinity of the anode inlet I1 of the cell stack 102, a voltage sensor 168 for detecting concentration information corresponding to the concentration of the aqueous methanol solution supplied to the cell stack 102 using the electrochemical characteristics of the aqueous methanol solution and the cell A second temperature sensor 170 for detecting the temperature of the aqueous methanol solution supplied to the stack 102 is provided. Further, an outside air temperature sensor 171 for detecting the outside air temperature is provided in the vicinity of the air filter 142. The voltage sensor 168 detects an open circuit voltage of the fuel cell (fuel cell) 104 and uses the voltage value as electrochemical concentration information.

The electrical configuration of such a fuel cell system 100 will be described with reference to FIG.
The controller 156 of the fuel cell system 100 performs necessary calculations to control the operation of the fuel cell system 100, a clock circuit 174 for supplying a clock to the CPU 172, a program and data for controlling the operation of the fuel cell system 100 In addition, a memory 176 made of, for example, an EEPROM for storing calculation data, a reset IC 178 for preventing malfunction of the fuel cell system 100, an interface circuit 180 for connecting to an external device, and an electric motor 60 for driving the motorcycle 10 The voltage detection circuit 184 for detecting the voltage in the electric circuit 182 for connecting the cell stack 102 to the battery cell 102, the current detection circuit 186 for detecting the current flowing through the fuel cell 104 and the cell stack 102, and the electric circuit 182 are opened. An ON / OFF circuit 188 for preventing the overvoltage, a voltage protection circuit 190 for preventing an overvoltage of the electric circuit 182, a diode 192 provided in the electric circuit 182, and a power supply circuit 194 for supplying a predetermined voltage to the electric circuit 182. Including.

  The CPU 172 of the controller 156 includes a detection signal from the ultrasonic sensor 164, voltage sensor 168, first temperature sensor 166, second temperature sensor 170, and outside air temperature sensor 171, and a current detection value from the current detection circuit 186. Is entered. The CPU 172 also has a detection signal from the fall switch 196 that detects the presence or absence of a fall, an input signal from the main switch 152 for turning on and off the power, and a signal from the input unit 30c for various settings and information input. Is given. Further, the CPU 172 is also provided with detection signals from the level sensors 129, 131 and 133.

  In the memory 176 that is a storage means, in addition to a program for executing the operation shown in FIG. 13 and calculation data, etc., physical concentration information of the aqueous methanol solution obtained by the ultrasonic sensor 164 (corresponding to the ultrasonic propagation velocity) Conversion information for converting the voltage concentration) into the concentration, and the conversion information for converting the electrochemical concentration information (the open circuit voltage of the fuel cell 104) of the aqueous methanol solution obtained by the voltage sensor 168 into the concentration. The These pieces of conversion information are, for example, table data indicating the correspondence between sensor output information and the corresponding density.

  Further, the memory 176 stores the energization time (methanol fuel input amount) of the fuel pump 136 based on the concentration information consisting of the value (current integrated value) obtained by integrating the current obtained by the current detection circuit 186 by the CPU 172. ) Is stored as table data, for example. The memory 176 stores data indicating the target concentration of the aqueous methanol solution.

  The CPU 172 controls auxiliary equipment such as the fuel pump 136, the aqueous solution pump 146, the air pump 148, the water pump 160, the cooling fans 120 and 126, the detection valve 138, and the rust prevention valve 158. Further, the CPU 172 controls the display unit 30b for displaying various information and notifying various information to the rider of the motorcycle.

  Further, a secondary battery 134 and a drive unit 62 are connected to the cell stack 102. The secondary battery 134 and the drive unit 62 are connected to the electric motor 60. The secondary battery 134 complements the output from the cell stack 102, is charged by the electric energy from the cell stack 102, and gives electric energy to the electric motor 60 and the auxiliary devices by the discharge.

  A meter 30 a for measuring various data of the electric motor 60 is connected to the electric motor 60, and the data measured by the meter 30 a and the state of the electric motor 60 are given to the CPU 172 via the interface circuit 198.

  In this embodiment, the voltage sensor 168 corresponds to the first concentration detection unit, and the current detection circuit 186 and the CPU 172 correspond to the second concentration detection unit. The fuel supply means including the pipes P1 and P2 and the fuel pump 136, the water supply means including the pipes P15 and P16 and the water pump 160, and the CPU 172 correspond to the concentration adjusting means. The fuel supply means only needs to include at least the fuel pump 136, and the water supply means only needs to include at least the water pump 160.

Next, main operations during operation of the fuel cell system 100 will be described.
When the main switch 152 is turned on, the fuel cell system 100 drives auxiliary equipment such as the aqueous solution pump 146 and the air pump 148 and starts operation.

  By driving the aqueous solution pump 146, the aqueous methanol solution stored in the aqueous solution tank 130 is sent from the pipe P 3 side to the pipe P 4 side and supplied to the aqueous solution filter 144. The methanol aqueous solution from which impurities and the like have been removed by the aqueous solution filter 144 is directly supplied to the anode 104b of each fuel cell 104 constituting the cell stack 102 via the pipe P5 and the anode inlet I1.

  On the other hand, the air (air) drawn from the air filter 142 by driving the air pump 148 is silenced by flowing into the air chamber 150 via the pipe P8. Then, the sucked air and the gas from the catch tank 140 given to the air chamber 150 are supplied to the cathode 104c of each fuel cell 104 constituting the cell stack 102 via the pipes P9 to P11 and the cathode inlet I3. The

  In the anode 104b of each fuel cell 104, methanol and water in the supplied aqueous methanol solution chemically react to generate carbon dioxide and hydrogen ions. The generated hydrogen ions flow into the cathode 104c through the electrolyte 104a, and electrochemically react with oxygen in the air supplied to the cathode 104c side to generate water (water vapor) and electric energy. That is, power generation is performed in the cell stack 102. The generated electrical energy is sent to and stored in the secondary battery 134 and is used for driving the motorcycle 10 and the like.

  On the other hand, the carbon dioxide and unreacted methanol aqueous solution generated at the anode 104b of each fuel cell 104 rise in temperature due to the heat generated by the electrochemical reaction (for example, about 65 ° C. to 70 ° C.), and unreacted methanol. A part of the aqueous solution is vaporized. The carbon dioxide and the unreacted aqueous methanol solution flow into the aqueous solution radiator 112 via the anode outlet I2 of the cell stack 102, and are cooled by the fan 120 while flowing through the radiator pipe 116 (for example, about 40 ° C.). . The cooled carbon dioxide and the unreacted methanol aqueous solution are returned to the aqueous solution tank 130 via the pipe P7.

  On the other hand, most of the water vapor generated at the cathode 104c of each fuel cell 104 is liquefied and converted into water and discharged from the cathode outlet I4 of the cell stack 102, but the saturated water vapor is discharged in a gas state. A part of the water vapor discharged from the cathode outlet I4 is cooled by the radiator 114 and liquefied by lowering the dew point. The water vapor liquefaction operation by the radiator 114 is performed by operating the fan 126. Water (water and water vapor) from the cathode outlet I4 is supplied to the water tank 132 through the pipe P12, the radiator 114 and the pipe P13 together with unreacted air.

  Further, in the cathode 104c of each fuel cell 104, the vaporized methanol from the catch tank 140 and the methanol moved to the cathode by the crossover react with oxygen in the platinum catalyst layer and decompose into harmless moisture and carbon dioxide. . Moisture and carbon dioxide decomposed from methanol are discharged from the cathode outlet I4 and supplied to the water tank 132 via the radiator 114. Further, the water moved to the cathode 104c of each fuel cell 104 due to the water crossover is discharged from the cathode outlet I4 and supplied to the water tank 132 via the radiator 114.

  The water collected in the water tank 132 is appropriately refluxed to the aqueous solution tank 130 through the pipes P15 and P16 by driving the water pump 160, and used as water of the methanol aqueous solution.

  In the fuel cell system 100 in operation, the concentration detection process of the aqueous methanol solution is periodically executed in order to cause each fuel cell 104 to efficiently generate power while preventing the deterioration of each fuel cell 104. Based on the detection result, the methanol concentration of the aqueous methanol solution to be supplied to the cell stack 102 is adjusted. Specifically, based on the detection result of the methanol concentration, the methanol fuel in the fuel tank 128 is supplied to the aqueous solution tank 130, and the water in the water tank 132 is returned to the aqueous solution tank 130.

FIG. 12 shows data when the oxidant deficiency process is executed in such a fuel cell system 100.
In a period immediately after the execution of the oxidant deficiency process shown in the period (2) of FIG. 12, the voltage generated due to the lack of the reactive oxidant (oxygen) decreases. Therefore, the change characteristic of the open circuit voltage of the fuel cell 104 is greatly different from the change characteristic of the concentration of the methanol aqueous solution, and the correlation between the open circuit voltage and the concentration of the methanol aqueous solution becomes low. Cannot be detected accurately. On the other hand, if the current from the fuel cell 104, that is, the cell stack 102 is detected and integrated, the amount of fuel consumed and the concentration of aqueous methanol solution can be estimated from the amount of electric power taken out. Therefore, in a period immediately after the execution of the oxidant deficiency process shown in the period (2), it is possible to obtain higher detection accuracy by detecting the concentration of the aqueous methanol solution based on the current value from the fuel cell 104 rather than the open circuit voltage. . That is, the density adjustment is executed based on the density information from the output of the current detection circuit 186 without using the density information of the open circuit voltage of the voltage sensor 168.

  Then, if the open circuit voltage falls below the value before the oxidant deficiency treatment, it is judged that the reaction has been sufficiently performed and the open circuit voltage has returned to a stable state, and in the period (3), the aqueous methanol solution based on the open circuit voltage Concentration is used. In FIG. 12, since the scale of the vertical axis of the graph is large, it is difficult to grasp that the open circuit voltage has fallen below the value before the oxidant deficiency treatment, but it should be noted that it is clearly below at time point P.

  In this embodiment, the concentration is adjusted using the concentration of the aqueous methanol solution based on the open circuit voltage in the periods (1) and (3), and the concentration of the aqueous methanol solution based on the current from the fuel cell 104 is used in the period (2). To adjust the density.

The operation of the fuel cell system 100 will be described with reference to FIG.
The operation shown in FIG. 13 is performed at a relatively high temperature where the detection accuracy of the voltage sensor 168 is high. For example, the operation detected by the second temperature sensor 170 is performed at 45 ° C. or higher.

  First, the open circuit voltage detected by the voltage sensor 168 before the oxidant deficiency process is stored in the memory 176 (step S1). At this time, the open circuit voltage may be acquired a plurality of times and an average value may be taken. When the open circuit voltage is low, the concentration of the aqueous methanol solution is high, and when the open circuit voltage is high, the concentration of the aqueous methanol solution is low.

  Next, the air pump 148 is stopped and the oxidant deficiency process is executed (step S3). After a predetermined time, the driving of the air pump 148 is resumed (step S5), and the current from the fuel cell 104, that is, the cell stack 102 is detected by the current detection circuit 186. (Step S7), and the current value is integrated for a predetermined period by the CPU 172 to obtain an integrated current value (step S9). Then, the CPU 172 refers to conversion information for obtaining the fuel pump energizing time from the accumulated current value stored in the memory 176, determines the energizing time of the fuel pump 136 corresponding to the accumulated current value (step S11), and the fuel pump 136 is energized and methanol fuel is supplied into the aqueous solution tank 130 (step S13). Only at this time, a table set so that the energization time (pump drive time) of the fuel pump 136 corresponding to the concentration is slightly longer is used so that the concentration of the aqueous methanol solution is slightly higher than the target concentration. This induces the open circuit voltage to quickly fall below the value before the oxidant deficiency treatment.

  Then, the CPU 172 determines whether or not a certain time (9 minutes in this embodiment) has elapsed (step S15). If the certain time has not elapsed, the open circuit voltage stored in the memory 176 is deficient in oxidant. The CPU 172 determines whether or not the value before the processing is lower, that is, whether or not the concentration information of the aqueous methanol solution indicates a higher concentration than the concentration information before the oxidizing agent deficiency processing (step S17).

  In step S17, if the open circuit voltage is not lower than the value before the oxidant deficiency treatment, it is determined that the open circuit voltage has not returned to a normal value, and the process returns to step S7.

  On the other hand, if the open circuit voltage falls below the value before the oxidant deficiency treatment, it is determined that the open circuit voltage has returned to the normal value, and the process proceeds to step S19. In step S15, the process also proceeds to step S19 when a predetermined time has elapsed.

  In step S19, the CPU 172 refers to the conversion information stored in the memory 176, and detects the concentration of the aqueous methanol solution based on the open circuit voltage. Based on the comparison between the detected concentration and the target concentration, the energization time of the fuel pump 136 and the energization time of the water pump 160 are determined (step S21). At this time, the energization time of the fuel pump 136 and the water pump 160 is determined in consideration of the water level of the aqueous solution tank 130.

  Then, the pump whose energization time is determined is energized for that time, whereby methanol fuel and / or water is supplied into the aqueous solution tank 130, and the concentration of the aqueous methanol solution and the amount of the aqueous solution in the aqueous solution tank 130 become the target concentration and amount. Adjustment is made (step S23), and the process ends. In this way, the concentration adjustment of the aqueous methanol solution when the oxidant deficiency treatment is executed is performed.

  According to such a fuel cell system 100, immediately after execution of the oxidant deficiency process, concentration information of the aqueous methanol solution can be acquired based on the current from the fuel cell 104, so that a decrease in concentration detection accuracy can be suppressed, and oxidant deficiency Even when processing is performed, the detection accuracy of the fuel concentration of the aqueous methanol solution can be maintained high.

  Further, by adding a large amount of high-concentration methanol fuel so that the concentration of the methanol aqueous solution exceeds the target concentration, the open circuit voltage is returned to the value before the oxidant depletion treatment in a shorter time, that is, the detection accuracy of the voltage sensor 168. Can be quickly returned to normal, and the means used for density adjustment can be switched from the current detection circuit 186 to the voltage sensor 168 at an early stage. As a result, the fuel concentration can be accurately adjusted even when the oxidant deficiency treatment is performed.

  In the density detection process in the normal mode, density information from the current detection circuit 186 may be added to density information from the voltage sensor 168. Further, after the oxidant deficiency treatment, the concentration information from the current detection circuit 186 may be added with the concentration information from another detection means.

  In order to improve the power generation efficiency, the oxidant-deficient treatment is executed in motorcycles, including automobiles, ships, etc., including the fuel cell system, so that the present invention is suitable for any of these transportation equipments. Used.

  In the above-described embodiment, the voltage sensor 168 is used as the first concentration detecting means for electrochemically detecting the concentration information of the aqueous methanol solution. However, the present invention is not limited to this, for example, US Pat. No. 6,254, Any sensor that detects the concentration electrochemically, such as the sensor disclosed in US Pat. No. 748, can be used. Further, instead of detecting the open circuit voltage of the fuel cell 104 by the voltage sensor 168, the open circuit voltage of the cell stack 102 may be detected and used as concentration information.

  In the above-described embodiment, the second concentration detection unit includes the current detection circuit 186, but is not limited thereto, and any unit that detects concentration information by a method different from the first concentration detection unit can be used. . In this embodiment, any sensor other than the voltage sensor 168 that detects an open circuit voltage can be used.

  The conversion information may be an arithmetic expression for converting density information into density.

  In the above embodiment, methanol is used as the fuel, and methanol aqueous solution is used as the fuel aqueous solution. However, the present invention is not limited to this. Good.

1 is a left side view showing a motorcycle according to an embodiment of the present invention. It is the perspective view which looked at the arrangement state of the fuel cell system with respect to the body frame of a motorcycle from the diagonally left front. It is the perspective view which looked at the arrangement state of the fuel cell system with respect to the body frame of a motorcycle from diagonally left rear. It is a left view which shows the piping state of a fuel cell system. It is a right view which shows the piping state of a fuel cell system. It is the perspective view which looked at the piping state of the fuel cell system from diagonally left forward. It is the perspective view which looked at the piping state of the fuel cell system from diagonally right forward. It is an illustration figure which shows a fuel cell stack. It is an illustration figure which shows a fuel cell. It is a system diagram which shows piping of a fuel cell system. It is a block diagram which shows the electric constitution of a fuel cell system. It is a graph which shows the data at the time of performing an oxidant deficiency process. It is a flowchart which shows an example of operation | movement of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Motorcycle 100 Fuel cell system 102 Fuel cell stack 104 Fuel cell (fuel cell)
136 Fuel pump 156 Controller 160 Water pump 164 Ultrasonic sensor 168 Voltage sensor 172 CPU
176 Memory 186 Current detection circuit P1 to P22 Pipe

Claims (5)

A fuel cell that generates electrical energy through an electrochemical reaction;
First concentration detecting means for detecting concentration information corresponding to the concentration of the aqueous fuel solution by using electrochemical characteristics of the aqueous fuel solution used for generating electric energy in the fuel cell;
Second concentration detection means for detecting concentration information corresponding to the concentration of the aqueous fuel solution by a method different from the first concentration detection means;
Storage means for storing the concentration information detected before the oxidant deficiency treatment by the first concentration detection means; and after the oxidant deficiency treatment, the concentration is adjusted based on the concentration information detected by the second concentration detection means, and The concentration of the aqueous fuel solution is adjusted to be higher than the target concentration, and the concentration information detected by the first concentration detection means after the oxidant deficiency treatment is higher than the concentration information stored in the storage means. A fuel cell system comprising a concentration adjusting means for adjusting the concentration of the aqueous fuel solution based on the concentration information detected by the first concentration detecting means.   2. The fuel cell system according to claim 1, wherein the second concentration detection unit detects concentration information of the aqueous fuel solution based on a current from the fuel cell.   A motorcycle including the fuel cell system according to claim 1.   A transportation device including the fuel cell system according to claim 1. A fuel cell that generates electric energy by an electrochemical reaction, and firstly detects concentration information corresponding to the concentration of the aqueous fuel solution using the electrochemical characteristics of the aqueous fuel solution used for generating electric energy in the fuel cell. Concentration of a fuel cell system comprising: concentration detection means; second concentration detection means for detecting concentration information corresponding to the concentration of the aqueous fuel solution by a method different from the first concentration detection means; and storage means capable of storing concentration information An adjustment method,
Storing concentration information detected by the first concentration detection means before the oxidant deficiency treatment in the storage means;
Adjusting the concentration of the aqueous fuel solution to be higher than a target concentration based on the concentration information detected by the second concentration detection means after the oxidant deficiency processing; and the oxidant deficiency by the first concentration detection means A step of adjusting the concentration of the aqueous fuel solution based on the concentration information detected by the first concentration detection means when the concentration information detected after processing indicates a higher concentration than the concentration information stored in the storage means; A method for adjusting the concentration of a fuel cell system.

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