JP5152546B2 - Fuel cell system and moving body - Google Patents

Description

  The present invention relates to a fuel cell system and a moving body.

  Currently, a fuel cell system including a fuel cell that receives a supply of reaction gas (fuel gas and oxidizing gas) and generates electric power has been proposed and put into practical use. When power generation is performed with such a fuel cell system, moisture is generated inside the fuel cell due to an electrochemical reaction, but this moisture stays in the reaction gas flow path in the fuel cell, preventing the flow of the reaction gas. There is. In addition, when the fuel cell system is operated under a low temperature environment such as below freezing point, moisture existing inside the electrode (catalyst layer or diffusion layer) of the fuel cell may freeze and start-up performance may be significantly reduced. .

In order to solve various problems due to moisture generated inside the fuel cell in this way, in recent years, when the operation of the fuel cell is stopped, dry oxygen is supplied to the reaction gas flow path according to the wet state in the fuel cell. A technique (scavenging technique) for removing moisture in the fuel cell by supplying dry hydrogen is proposed (for example, see Patent Document 1).
JP 2002-208421 A

  By the way, the fuel cell may be mounted on various mobile bodies (vehicles, robots, ships, aircrafts, etc.) and serve as a drive source. When the fuel cell is fixed to the mobile body, The attitude of the fuel cell also changes according to the attitude. For example, when the fuel cell is fixed to the vehicle body of the fuel cell vehicle, if the vehicle body is tilted after stopping on the slope of the fuel cell vehicle, the fuel cell is also tilted accordingly.

  However, since the conventional scavenging technique described in Patent Document 1 does not consider changes in the attitude of the fuel cell, effective scavenging can be performed when the fuel cell is inclined as described above. It was difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to perform appropriate scavenging control in accordance with the inclination state of the moving body in a fuel cell system including a fuel cell fixed to the moving body.

  In order to achieve the above object, a fuel cell system according to the present invention includes a fuel cell fixed to a moving body, and scavenging means for discharging moisture in the fuel cell to the outside by supplying gas into the fuel cell. The scavenging control means for setting the gas supply condition to the fuel cell by the scavenging means in accordance with the inclination state of the moving body is provided.

  According to such a configuration, the gas supply condition (scavenging condition) to the fuel cell by the scavenging means can be set according to the inclination state of the moving body to which the fuel cell is fixed. For example, when the moving body is inclined so that the moisture in the fuel cell is not easily discharged to the outside, the gas supply conditions can be set so as to promote the discharge of moisture. As a result, it is possible to suppress the occurrence of various problems (for example, a decrease in starting performance in a low temperature environment) caused by moisture remaining in the fuel cell.

  In the fuel cell system, the scavenging control means sets gas supply conditions that promote the discharge of moisture when the moving body is inclined so that the moisture in the fuel cell is not easily discharged to the outside. When the moving body is inclined so that the moisture in the fuel cell can be easily discharged to the outside, it is possible to set a gas supply condition that suppresses the discharge of moisture.

  For example, the scavenging control means sets the gas supply pressure to the fuel cell by the scavenging means to be large (increase the supply flow rate) when the moving body is inclined so that the moisture in the fuel cell is not easily discharged to the outside. On the other hand, when the moving body is inclined so that the moisture in the fuel cell is easily discharged to the outside, the gas supply pressure to the fuel cell by the scavenging means can be set small (the supply flow rate is small). . The scavenging control means sets the gas supply time to the fuel cell by the scavenging means longer when the moving body is inclined so that the moisture in the fuel cell is not easily discharged outside. When the moving body is inclined so that the water is easily discharged to the outside, the gas supply time to the fuel cell by the scavenging means can be set short.

  By doing in this way, even when the moving body is inclined so that the water in the fuel cell is not easily discharged to the outside, the discharge of the water in the fuel cell can be promoted. As a result, it is possible to suppress a decrease in start-up performance due to the generated water remaining in the fuel cell in a low temperature environment. On the other hand, when the moving body is inclined so that the water in the fuel cell is easily discharged to the outside, the discharge of the water in the fuel cell can be suppressed. As a result, it is possible to suppress the occurrence of dry-up in the fuel cell (insufficient water in the electrolyte membrane) and to save energy necessary for scavenging.

  Moreover, the moving body which concerns on this invention is provided with the said fuel cell system.

  According to such a configuration, since the fuel cell system capable of performing appropriate scavenging control according to the inclination state of the moving body is provided, it has excellent start-up performance in a low-temperature environment and energy necessary for scavenging. It is possible to provide a mobile object that can reduce the cost.

  ADVANTAGE OF THE INVENTION According to this invention, in a fuel cell system provided with the fuel cell fixed to a moving body, it becomes possible to perform suitable scavenging control according to the inclination state of a moving body.

  Hereinafter, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an on-vehicle power generation system of a fuel cell vehicle 100 (FIGS. 2 and 3) as a moving body will be described.

  First, the structure of the fuel cell system 1 according to the embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the fuel cell system 1 according to the present embodiment includes a fuel cell 10 that generates electric power upon receiving a supply of reaction gas (oxidation gas and fuel gas), and the fuel cell 10 has an oxidant gas. An oxidizing gas piping system 2 for supplying the air, a hydrogen gas piping system 3 for supplying hydrogen gas as a fuel gas to the fuel cell 10, a control device 4 for integrated control of the entire system, and the like.

  The fuel cell 10 has a stack structure in which a required number of unit cells that generate power upon receiving a reaction gas are stacked. The electric power generated by the fuel cell 10 is supplied to a PCU (Power Control Unit) 11. The PCU 11 includes an inverter that supplies electric power to the traction motor 12 of the fuel cell vehicle 100, an inverter that supplies electric power to various auxiliary devices such as a compressor motor and a hydrogen pump motor, charging the secondary battery, and from the secondary battery. It includes a DC-DC converter that supplies power to motors.

  The oxidant gas piping system 2 includes an air supply passage 21 that supplies the oxidant gas (air) humidified by the humidifier 20 to the fuel cell 10, and an air exhaust that guides the oxidant off-gas discharged from the fuel cell 10 to the humidifier 20. A flow path 22 and an exhaust flow path 23 for guiding the oxidizing off gas from the humidifier 21 to the outside are provided. The air supply passage 21 is provided with a compressor 24 that takes in the oxidizing gas in the atmosphere and pumps it to the humidifier 20. The operation of the compressor 24 is controlled by the control device 4.

  The hydrogen gas piping system 3 includes a hydrogen tank 30 as a fuel supply source storing high-pressure hydrogen gas, a hydrogen supply flow path 31 for supplying the hydrogen gas in the hydrogen tank 30 to the fuel cell 10, and the fuel cell 10. A circulation flow path 32 for returning the discharged hydrogen off-gas to the hydrogen supply flow path 31.

  The hydrogen supply flow path 31 is provided with a shutoff valve 33 that shuts off or allows the supply of hydrogen gas from the hydrogen tank 30 and a regulator 34 that adjusts the pressure of the hydrogen gas. In the present embodiment, a modulatable pressure regulator 34 that can change the target value of the supply pressure by a step motor is employed. The operations of the shut-off valve 33 and the regulator 34 are controlled by the control device 4.

  A discharge channel 37 is connected to the circulation channel 32 via a gas-liquid separator 35 and an exhaust drain valve 36. The gas-liquid separator 35 collects moisture from the hydrogen off gas. The exhaust / drain valve 36 is operated according to a command from the control device 4 to discharge (purge) moisture collected by the gas-liquid separator 35 and hydrogen off-gas containing impurities in the circulation flow path 32 to the outside. Is. The circulation channel 32 is provided with a hydrogen pump 38 that pressurizes the hydrogen off-gas in the circulation channel 32 and sends it to the hydrogen supply channel 31 side. The gas in the discharge channel 37 is diluted by a diluter (not shown), and merges with the gas in the exhaust channel 23 in the discharge pipe 39.

  Further, as shown in FIG. 2, the fuel cell 10 is fixed to the vehicle body in a state where the fuel cell 10 is disposed at a substantially central portion in the front-rear direction of the fuel cell vehicle 100. The gas flow path inside the fuel cell 10 is set so as to be substantially horizontal when the fuel cell vehicle 100 travels horizontally, and the outlet for the water flowing in the gas flow path is located behind the fuel cell 10. Is provided. In addition, various pipes (exhaust flow path 23, discharge flow path 37, discharge pipe 39, etc.) connected to the fuel cell 10 are connected to the fuel cell vehicle 100 from the substantially central part in the front-rear direction of the fuel cell vehicle 100 toward the rear. It is arranged so as to be substantially horizontal when traveling horizontally. Therefore, when the fuel cell vehicle 100 travels downhill as shown in FIG. 2 (a), the discharge pipe 39 is inclined so that the outlet side of the discharge pipe 39 is located above the fuel cell 10 side. When the fuel cell vehicle 100 travels uphill as shown in FIG. 2B, the discharge pipe 39 is inclined so that the outlet side of the discharge pipe 39 is positioned below the fuel cell 10 side.

  Further, the fuel cell vehicle 100 is equipped with a tilt sensor (not shown) that detects a tilt angle θ in the front-rear direction. In the present embodiment, as shown in FIG. 2A, the inclination angle of the discharge pipe 39 with respect to the horizontal plane when the outlet side of the discharge pipe 39 is positioned higher than the fuel cell 10 side is the positive angle of the fuel cell vehicle 100. The inclination angle (+ θ). Further, as shown in FIG. 2B, the inclination angle of the discharge pipe 39 with respect to the horizontal plane when the outlet side of the discharge pipe 39 is located below the fuel cell 10 side is defined as the negative inclination angle (− θ). Information relating to the inclination angle θ of the fuel cell vehicle 100 detected by the inclination sensor is transmitted to the control device 4 and used for scavenging control.

  The control device 4 receives control information such as an accelerator signal (required load) of a vehicle (not shown) and controls operations of various devices in the system. The control device 4 is configured by a computer system (not shown). Such a computer system includes a CPU, ROM, RAM, HDD, input / output interface, display, and the like, and various control operations are realized by the CPU reading and executing various control programs recorded in the ROM. It is like that.

  Specifically, the control device 4 drives and controls the compressor 24, the shut-off valve 33, and the regulator 34 to supply gas (oxidizing gas and hydrogen gas) into the fuel cell 10 to thereby remove moisture in the fuel cell 10. Carry out “scavenging” exhausted to the outside. That is, the compressor 24, the shutoff valve 33, the regulator 34, and the control device 4 constitute one embodiment of the scavenging means in the present invention. The control device 4 temporarily suppresses or stops humidification of the oxidizing gas by the humidifier 20 when performing scavenging. It should be noted that the control device 4 in the present embodiment scavenges both when the operation of the fuel cell 10 is stopped (when power generation is stopped) and when the fuel cell 10 is purged (discharge of gas in the circulation passage 32). Control shall be performed.

  In addition, the control device 4 sets an appropriate scavenging condition according to the inclination state of the fuel cell vehicle 100. Specifically, as shown in FIG. 2 (a), the control device 4 uses a gas that promotes the discharge of moisture in a state where the moisture in the fuel cell 10 is hard to be discharged to the outside at a positive inclination angle (+ θ). Set the supply conditions. On the other hand, as shown in FIG. 2 (b), the control device 4 supplies gas that suppresses the discharge of moisture in a state where the moisture in the fuel cell 10 is easily discharged to the outside at an inclination angle of negative (−θ). Set conditions. That is, the control device 4 functions as an embodiment of the scavenging control means in the present invention.

  The control device 4 in this embodiment performs scavenging control using a map as shown in FIG. That is, the control device 4 decreases the supply pressure P of the gas to the fuel cell 10 and decreases the supply flow rate Q as the inclination angle θ of the fuel cell vehicle 100 is smaller (the inclination angle is negative and the absolute value is larger). In addition to setting, the gas supply time T to the fuel cell 10 is set short. In other words, the control device 4 increases the gas supply pressure P to the fuel cell 10 and increases the supply flow rate Q as the inclination angle θ of the fuel cell 100 increases (the inclination angle is positive and the absolute value increases). While setting many, the supply time T of the gas to the fuel cell 10 is set long.

  Next, a scavenging operation after the operation stop of the fuel cell system 1 according to the present embodiment will be described using the flowchart of FIG.

  During normal operation of the fuel cell system 1, hydrogen gas is supplied from the hydrogen tank 30 to the fuel electrode of the fuel cell 10 through the hydrogen supply channel 31, and the air that has been subjected to humidification adjustment passes through the air supply channel 21. Then, power is generated by being supplied to the oxidation electrode of the fuel cell 10. At this time, the power (required power) to be drawn from the fuel cell 10 is calculated by the control device 4, and hydrogen gas and air in an amount corresponding to the amount of power generation are supplied into the fuel cell 10. During normal operation, the fuel cell 10 is in a wet state, so that when the operation is stopped, moisture remains in the fuel cell 10. In the present embodiment, “scavenging” for discharging the moisture in the fuel cell 10 to the outside is performed after the normal operation is stopped.

  That is, first, the control device 4 of the fuel cell system 1 determines the presence or absence of an operation stop signal due to an ignition switch OFF operation or the like (operation stop determination step: S1). And the control apparatus 4 detects the inclination angle of the fuel cell vehicle 100 using an inclination sensor, when an operation stop signal is detected (inclination angle detection process: S2).

Next, the control device 4 sets a scavenging condition corresponding to the inclination angle detected in the inclination angle detection step S2 based on the map shown in FIG. 3 (scavenging condition setting step: S3). For example, when the fuel cell vehicle 100 is stopped on a downhill and the inclination angle is “θ ₁ ” (when the water in the fuel cell 10 is difficult to be discharged to the outside), the control device 4 supplies the gas supply The pressure, gas supply flow rate, and gas supply time are set to “P ₅ ”, “Q ₅ ”, and “T ₅ ”, respectively. In addition, when the fuel cell vehicle 100 is stopped on an uphill and the inclination angle is “−θ ₂ ” (when water in the fuel cell 10 is easily discharged to the outside), the control device 4 The supply pressure, gas supply flow rate, and gas supply time are set to “P ₂ ”, “Q ₂ ”, and “T ₂ ”, respectively.

  Next, the control device 4 drives and controls the compressor 24, the shutoff valve 33, and the regulator 34 so as to realize the scavenging conditions set in the scavenging condition setting step S3, and gas (oxidizing gas and hydrogen gas) in the fuel cell 10. , The water remaining in the fuel cell 10 is discharged to the outside (scavenging step: S4). In the scavenging step S4, the control device 4 keeps the exhaust drain valve 36 open, and the water discharged from the fuel cell 10 to the circulation flow path 32 passes through the discharge flow path 37 and the discharge pipe 39 to the fuel cell vehicle 100. To discharge outside.

  In the fuel cell system 1 according to the embodiment described above, the scavenging conditions can be set according to the inclination state of the fuel cell vehicle 100 to which the fuel cell 10 is fixed. That is, when the fuel cell vehicle 100 is inclined so that the moisture in the fuel cell 10 is not easily discharged to the outside (when the inclination angle is positive), the gas supply conditions are set so as to promote the discharge of moisture. can do. As a result, it is possible to suppress the occurrence of various problems (for example, a decrease in starting performance in a low temperature environment) due to the moisture remaining in the fuel cell 10. In addition, when the fuel cell vehicle 100 is inclined so that the moisture in the fuel cell 10 is easily discharged to the outside (when the inclination angle is negative), the gas supply conditions are set so as to suppress the discharge of moisture. can do. As a result, the occurrence of dry-up (insufficient water in the electrolyte membrane) in the fuel cell 10 can be suppressed, and energy required for scavenging can be reduced.

  Moreover, since the fuel cell vehicle 100 (moving body) according to the embodiment described above includes the fuel cell system 1 capable of performing appropriate scavenging control according to the inclination state, it is excellent in a low temperature environment. Thus, it is possible to reduce the energy required for scavenging.

  In the above embodiment, the example in which the circulation channel 32 is provided in the hydrogen gas piping system 3 of the fuel cell system 1 has been shown. For example, as shown in FIG. Can be directly connected to eliminate the circulation flow path 32. Even when such a configuration (dead end method) is adopted, the same effect as that of the above embodiment can be obtained by performing the scavenging control similar to that of the above embodiment with the control device 4.

  In the above embodiment, the scavenging control is performed after the normal operation of the fuel cell 10 is stopped. However, the scavenging control can also be performed when the purge operation is performed during the normal operation. In such a case, as shown in FIG. 6, the control device 4 determines whether or not it is time to execute the purge operation (purge determination step: S11). When it is determined that it is time to execute the purge operation, the control device 4 detects the inclination angle of the fuel cell vehicle 100 (inclination angle detection step: S12). Thereafter, the control device 4 sets a scavenging condition corresponding to the detected inclination angle (scavenging condition setting step: S13), and drives and controls the compressor 24 and the like so as to realize the set scavenging condition. By supplying gas, moisture remaining in the fuel cell 10 is discharged to the outside (scavenging step: S14). The inclination angle detection step S12, the scavenging condition setting step S13, and the scavenging step S14 are the same as in the above embodiment.

  Moreover, in the above embodiment, although the example which set all the supply pressure, supply flow rate, and supply time of the gas into the fuel cell 10 according to the inclination angle of the fuel cell vehicle 100 was shown, gas supply conditions The (scavenging conditions) is not limited to this. For example, one of gas supply pressure, supply flow rate, and supply time may be set according to the inclination angle of the fuel cell vehicle 100. Further, the gas temperature can be set according to the inclination angle of the fuel cell vehicle 100, or the pulsation mode of the gas can be changed.

  Moreover, in the above embodiment, although the example which provided the hydrogen pump 38 in the circulation flow path 32 was shown, it replaces with the hydrogen pump 38 and may employ | adopt an ejector. Moreover, in the above embodiment, although the example which provided the exhaust drain valve 36 in the circulation flow path 32 which implement | achieves both exhaust_gas | exhaustion and waste_water | drain was shown, the water | moisture content collect | recovered with the gas-liquid separator 35 is discharged | emitted outside. A drain valve and an exhaust valve for discharging the gas in the circulation flow path 32 to the outside can be provided separately, and the drain valve and the exhaust valve can be controlled separately by the control device 4.

  In each of the above embodiments, the fuel cell system according to the present invention is mounted on the fuel cell vehicle. However, the present invention is applied to various mobile bodies (robots, ships, airplanes, etc.) other than the fuel cell vehicle. Such a fuel cell system can also be mounted.

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. FIG. 1 shows a fuel cell vehicle equipped with a fuel cell of the fuel cell system shown in FIG. 1, wherein (a) is a conceptual diagram showing a state of stopping on a downhill, and (b) is a state of stopping on an uphill. FIG. 3 is a map showing the relationship between the inclination angle of the fuel cell vehicle shown in FIG. 2 and scavenging conditions. 2 is a flowchart for explaining a scavenging operation after the operation of the fuel cell system shown in FIG. 1 is stopped. It is a block diagram which shows the modification of the fuel cell system shown in FIG. 2 is a flowchart for explaining a scavenging operation at the time of purging of the fuel cell system shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 4 ... Control apparatus (a part of scavenging means, scavenging control means), 10 ... Fuel cell, 24 ... Compressor (a part of scavenging means), 33 ... Shut-off valve (a part of scavenging means), 34 ... Regulator (part of scavenging means), 100 ... Fuel cell vehicle (moving body)

Claims (5)

In a fuel cell system comprising: a fuel cell fixed to a moving body; and scavenging means for discharging moisture in the fuel cell to the outside by supplying gas into the fuel cell.
A sensor that detects an inclination angle of the moving body in the front-rear direction when the operation of the fuel cell system is stopped;
And a scavenging control means for setting the supply conditions of the gas to the fuel cell by the scavenging means according to the inclination angle of the movable body, wherein the sensor detects,
The scavenging control means has a map that defines a correlation between an inclination angle of the moving body and a gas supply condition to the fuel cell, and the moisture in the fuel cell is discharged to the outside using the map. When the moving body is inclined so that it is difficult to be performed, the gas supply conditions are set such that the greater the absolute value of the detected inclination angle is, the more the moisture discharge is promoted. When the moving body is inclined so as to be easily discharged to the outside, a gas supply condition is set such that the greater the absolute value of the detected inclination angle is, the more the moisture discharge is suppressed.
Fuel cell system. The scavenging control means uses the map to determine a gas supply pressure to the fuel cell by the scavenging means when the moving body is inclined so that moisture in the fuel cell is not easily discharged to the outside. While the absolute value of the detected inclination angle is larger, the absolute value is set to be larger. On the other hand, when the moving body is inclined so that the moisture in the fuel cell is easily discharged to the outside, The gas supply pressure is set to be smaller as the absolute value of the detected tilt angle is larger .
The fuel cell system according to claim 1. The scavenging control means uses the map to determine the gas supply flow rate to the fuel cell by the scavenging means when the moving body is inclined so that the moisture in the fuel cell is not easily discharged to the outside. The larger the absolute value of the detected inclination angle is, the larger the value is set. On the other hand, when the moving body is inclined so that the moisture in the fuel cell is easily discharged to the outside, The gas supply flow rate is set to be smaller as the absolute value of the detected tilt angle is larger .
The fuel cell system according to claim 1. The scavenging control means uses the map to determine the gas supply time to the fuel cell by the scavenging means when the moving body is inclined so that the moisture in the fuel cell is not easily discharged to the outside. The longer the detected inclination angle is set, the longer it is set, while the scavenging means supplies gas to the fuel cell when the moving body is inclined so that the moisture in the fuel cell is easily discharged to the outside. The time is set shorter as the absolute value of the detected tilt angle is larger .
The fuel cell system according to claim 1. Comprising the fuel cell system according to any one of claims 1 to 4,
Moving body.

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