JP2005150006A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently use electric power when operating an oxygen enrichment apparatus in a fuel cell system. <P>SOLUTION: The oxygen enrichment apparatus 14 for producing oxygen enriched gas when it is operated with electric power is disposed in a supply system of cathode gas to the fuel cell 2. Surplus electric power in the system which is not consumed in a motor 8 is used as electric power to operate the oxygen enrichment apparatus 14. For example, in case of the fuel cell system loaded on a vehicle, electric power is regenerated when reducing speed of a vehicle and the oxygen enrichment apparatus 14 is operated with the regenerated electric power. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates electric power to be supplied to a motor with a fuel cell, and in particular, a cathode gas supply system for a fuel cell includes an oxygen enrichment device for generating a cathode gas having a high oxygen concentration. The present invention relates to a fuel cell system.

A fuel cell is supplied with a fuel gas containing hydrogen (anode gas) at the anode and an oxidizing gas containing oxygen (cathode gas) at the cathode, causing an electrochemical reaction at both electrodes and generating an electromotive force. It is a mechanism to do. Cathode gas is generally supplied to the cathode by pumping air with a compression pump. However, in order to increase the power generation efficiency, the cathode gas is supplied to the cathode so that a cathode gas with a higher oxygen concentration can be obtained. A technique in which an oxygen enricher is arranged in the system has been proposed. As an oxygen enrichment device used in a fuel cell system, for example, as described in Patent Document 1, a magnetic field is generated between a casing and a rotor, and a difference in magnetic susceptibility between oxygen and nitrogen is utilized to generate nitrogen. As described in a magnetic field type device that separates oxygen from water and Patent Document 2 and Patent Document 3, an oxygen-enriched film is arranged in an air supply line, and the difference in permeability coefficient between oxygen and nitrogen is utilized. A membrane separation type apparatus for separating oxygen from nitrogen is known.
JP 2002-289245 A Japanese Patent Laid-Open No. 6-208553 JP 58-53165 A

  By the way, in order to produce | generate oxygen-enriched gas with an oxygen enrichment apparatus, the electric power for operating an oxygen enrichment apparatus is needed. For example, in the case of a magnetic field type device, electric power for rotating the rotor is required. Further, in the case of a membrane separation type apparatus, the oxygen-enriched membrane becomes a resistance and a pressure loss occurs. Therefore, it is necessary to supply power to the compression pump to compensate for this pressure loss.

  In a fuel cell system, how to efficiently use the power generated by the fuel cell is an important issue. Therefore, the oxygen enrichment apparatus should not be operated simply, but should be operated so that the power in the system can be used efficiently. However, in the conventional fuel cell system provided with the oxygen enrichment device, the contents of control for controlling the operation state of the oxygen enrichment device have not been sufficiently studied.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell system that enables efficient use of electric power in operating an oxygen enricher.

In order to achieve the above object, a first invention provides a fuel cell that generates electricity by being supplied with an anode gas containing hydrogen and a cathode gas containing oxygen;
A motor operated by electric power,
An oxygen enrichment device disposed in a supply system of a cathode gas to the fuel cell and operating with electric power to generate an oxygen enriched gas;
Control means for controlling the operating state of the oxygen enricher,
The control means supplies surplus power in the system that is not consumed by the motor to the oxygen enricher.

  Furthermore, the second invention is characterized in that, in the first invention, a storage means for storing the oxygen-enriched gas generated by the oxygen-enriching device is provided.

  Furthermore, a third invention is characterized in that, in the second invention, when the generated power of the fuel cell is insufficient with respect to the required power, oxygen-enriched gas is supplied from the storage means to the fuel cell. It is said.

  Furthermore, a fourth aspect of the present invention is the control device according to the second aspect, wherein when the storage amount of the storage unit is equal to or less than a predetermined value, the control unit controls the oxygen enricher regardless of a surplus state of power in the system. It is characterized by operating.

  Furthermore, a fifth aspect of the present invention is the control device according to any one of the second to fourth aspects, wherein the control means operates the oxygen enricher under a predetermined condition regardless of a surplus state of power in the system. It is characterized by being stopped.

A sixth invention provides a fuel cell system mounted on a vehicle in order to achieve the above object.
A fuel cell that generates electricity by supplying an anode gas containing hydrogen and a cathode gas containing oxygen;
An oxygen enrichment device disposed in a supply system of a cathode gas to the fuel cell and operating with electric power to generate an oxygen enriched gas;
Storage means for storing the oxygen-enriched gas produced by the oxygen-enriching device;
A drive motor that operates with electric power to drive the vehicle;
Regenerative means for regenerating deceleration energy of the vehicle as electric power;
Control means for controlling the operating state of the oxygen enricher;
Line switching means for switching the cathode gas supply line in the system,
During powering by the drive motor, the operation of the oxygen enrichment device is stopped by the control means, and the supply line is switched by the line switching means so that cathode gas is supplied to the fuel cell,
At the time of regeneration by the regeneration means, the oxygen enrichment apparatus is operated by the control means, and the line switching means allows the oxygen enriched gas generated by the oxygen enrichment apparatus to be stored in the storage means. The supply line can be switched.

  Further, the seventh invention is the sixth invention, wherein the oxygen enriched gas is supplied from the storage means to the fuel cell when the generated power of the fuel cell is insufficient with respect to the required power. The supply line is switched by a line switching means.

  Further, in an eighth aspect based on the sixth aspect, when the storage amount of the storage means is less than or equal to a predetermined value, the oxygen enrichment device is operated by the control means regardless of the driving state of the vehicle. In addition, the supply line is switched by the line switching means so that at least a part of the oxygen-enriched gas generated by the oxygen enrichment apparatus is stored in the storage means.

  Furthermore, a ninth invention is the invention according to any one of the sixth to eighth inventions, wherein, under a predetermined condition, the operation of the oxygen enrichment device is stopped by the control means regardless of the driving state of the vehicle. It is characterized by that.

  According to the first invention, since the oxygen enricher is operated by the surplus power in the system that is not consumed by the motor, the electric power can be effectively used.

  According to the second invention, surplus power in the system is stored by being replaced with oxygen-enriched gas, and can be used whenever necessary.

  According to the third invention, when the generated power of the fuel cell is insufficient with respect to the required power, the oxygen-enriched gas is supplied from the storage means to the fuel cell, so that the generated power of the fuel cell is used as the required power. Can be raised to match.

  According to the fourth invention, it is avoided that the oxygen-enriched gas cannot be supplied when necessary due to a shortage of the storage amount of the storage means.

  According to the fifth aspect, it is possible to prevent power consumption due to useless operation of the oxygen enricher.

  According to the sixth aspect of the invention, the oxygen enrichment device is not operated during power running when power is consumed by the drive motor, and the oxygen enrichment device is activated during regeneration when the power in the system is excessive. In addition to reducing the available power, the surplus power can be used effectively. Moreover, since the oxygen-enriched gas generated by the operation of the oxygen-enriching device is stored in the storage means, the surplus power is stored after being replaced by the oxygen-enriched gas, and can be used whenever necessary. become. That is, according to the present invention, it is possible to effectively use power in the entire system.

  According to the seventh invention, when the generated power of the fuel cell is insufficient with respect to the required power, the supply line is switched so that the oxygen-enriched gas is supplied from the storage means to the fuel cell. The generated power can be increased to meet the required power.

  According to the eighth invention, when the storage amount of the storage means decreases, the supply line is switched so that at least a part of the oxygen-enriched gas generated in the oxygen enrichment device is stored in the storage means. It is avoided that the oxygen-enriched gas cannot be supplied when necessary due to a shortage of the storage amount of the storage means.

  According to the ninth aspect, it is possible to prevent power consumption due to useless operation of the oxygen enricher.

Embodiment 1 FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of a fuel cell system as Embodiment 1 of the present invention. The fuel cell system is a vehicle fuel cell system mounted on a vehicle, and a fuel cell 2 that generates power by receiving supply of a fuel gas containing hydrogen (anode gas) and an oxidizing gas containing oxygen (cathode gas); A drive motor 8 is provided that operates by electric power to drive the vehicle. In FIG. 1, a line indicated by a dotted line indicates a power supply line in the system. First, the configuration of the power system in the fuel cell system will be described.

  In the present fuel cell system, the power generated by the fuel cell 2 is used as power for operating the drive motor 8. Since the generated power of the fuel cell 2 is DC power, the operating power of the drive motor 8 is AC power, so an inverter 6 is provided for converting DC power into AC power. Moreover, the secondary battery 4 for absorbing the imbalance of the supply and demand of electric power is also provided. During rapid acceleration, power generation may not be in time due to a delay in the supply of fuel (anode gas and cathode gas) to the fuel cell 2, and the generated power of the fuel cell 2 may be insufficient with respect to the required power of the drive motor 8. In such a case, insufficient power is supplied from the secondary battery 4 to the drive motor 8. Conversely, during deceleration, the generated power of the fuel cell 2 may exceed the required power of the drive motor 8. In such a case, surplus power is charged in the secondary battery 4.

  Further, the drive motor 8 according to the present fuel cell system also has a function as a generator that generates electric power by being supplied with a driving force. When the vehicle is decelerated, the deceleration energy can be regenerated as electric power by causing the drive motor 8 to function as a generator. The inverter 6 according to the present fuel cell system also functions as a converter. When the drive motor 8 functions as a generator, electric power obtained by regeneration (hereinafter referred to as regenerative power) is converted into AC power by the inverter 6. To DC power, and the secondary battery 4 is charged.

  This fuel cell system has an electric compression pump (pressurizer) 10 in addition to the drive motor 8 as a load of the electric power system. The compression pump 10 is disposed in a cathode gas supply line (hereinafter referred to as a cathode gas line) to the cathode 2 a of the fuel cell 2. Below, the structure of the supply system of the cathode gas in this fuel cell system is demonstrated.

  In FIG. 1, a line indicated by a solid line connected to the cathode 2 a of the fuel cell 2 indicates a cathode gas line. In the drawing, elements other than the cathode 2a constituting the fuel cell 2 such as an anode and an electrolyte membrane are not shown. The cathode gas line is provided with a compression pump 10 for sucking air and pumping it downstream as described above. A three-way switching valve 18 having three ports is disposed on the upstream side of the compression pump 10. The three-way switching valve 18 is an electromagnetic valve that switches the communication between the ports upon receiving an electric signal, and the compression pump 10 is connected to one of the ports. The oxygen enricher 14 and the filter 16 are connected to the other two ports. The oxygen enrichment apparatus 14 has an oxygen enriched film inside, and an oxygen enriched gas having a high oxygen concentration can be obtained by passing air through the oxygen enriched film. The filter 16 is a filter for removing dust in the air. Although there is no oxygen enrichment effect like the oxygen enrichment device 14, the pressure loss before and after the device is low. By switching the three-way switching valve 18 as necessary, either the oxygen enricher 14 or the filter 16 is selectively connected to the compression pump 10.

  The cathode gas line is branched into two lines on the downstream side of the compression pump 10. One branch line is connected to the cathode 2 a, and the other branch line is connected to the storage device 12. The storage device 12 is a pressure tank capable of storing compressed air. The storage device 12 is installed in the vicinity of the cathode 2a so that the gas flow path from the storage device 12 to the cathode 2a is as short as possible. A switching valve 22 is disposed on the branch line connected to the cathode 2 a, and another switching valve 20 is disposed on the branch line connected to the storage device 12. The switching valves 20 and 22 are electromagnetic valves that switch between open and closed states in response to the supply of electrical signals. When the switching valve 20 opens, the compression pump 10 and the storage device 12 communicate with each other, and when the switching valve 22 opens, compression is performed. The pump 10 communicates with the cathode 2a.

  In the fuel cell system, the switching control of the three-way switching valve 18 and the two switching valves 20 and 22 is performed by the control device 30 along with the flow rate control of the compression pump 10. The control device 30 performs switching control of the three-way switching valve 18 and the switching valves 20 and 22 based on information such as current value, wheel speed, and accelerator opening, and performs flow control of the compression pump 10. In FIG. 1, a line indicated by a solid thin line indicates a signal flow in the system. The current value is detected by a direct current sensor 32 attached to the inverter 6, and the wheel speed is detected by an encoder 34 attached to the drive motor 8. Further, the accelerator opening is detected by an accelerator opening sensor (not shown). Hereinafter, the switching control of the three-way switching valve 18 and the switching valves 20 and 22 and the flow rate control of the compression pump 10 by the control device 30 will be described in detail for each driving situation of the vehicle with reference to FIGS. I will explain it. In addition, in the cathode gas line in FIGS. 2 to 5, a portion indicated by a solid bold line is a line through which a gas flows, and an arrow indicates a flow direction. The part shown with the dashed-two dotted line in the figure has shown the line which gas does not flow.

  FIG. 2 is a diagram illustrating the flow of the cathode gas during powering of the vehicle, that is, during travel by the drive motor 8. During power running, the three-way switching valve 18 is switched so as to connect the filter 16 to the compression pump 10, and the switching valve 20 is closed and the switching valve 22 is opened. Thereby, the air which passed the filter 16 is compressed with the compression pump 10, and is supplied to the cathode 2a of the fuel cell 2 as cathode gas. Since the filter 16 has a lower resistance than the oxygen enrichment device 14 having an oxygen enrichment membrane, the filter 16 passes through the filter 16 without passing through the oxygen enrichment device 14 so that the air sucked into the compression pump 10 is reduced. The pressure loss can be suppressed, and the power consumption of the compression pump 10 can be reduced correspondingly.

  FIG. 3 is a diagram showing the flow of the cathode gas during regeneration, that is, when the drive motor 8 is caused to function as a generator (regeneration means). At the time of regeneration, the three-way switching valve 18 is switched to connect the oxygen enricher 14 to the compression pump 10, and the switching valve 20 is opened and the switching valve 22 is closed. Whether the vehicle is in a power running state or a regenerative state can be determined by the direction of the signal from the DC current sensor 32. Thus, the following effects can be obtained by switching the cathode gas supply line between regeneration and power running.

  In the oxygen enrichment device 14, a pressure difference is generated before and after the oxygen enriched film by the action of the suction force from the compression pump 10, and oxygen is separated from nitrogen in the air by this pressure difference. Thereby, an oxygen-enriched gas having a high oxygen concentration is generated downstream of the oxygen-enriched film, and the oxygen-enriched gas is compressed by the compression pump 10 and stored in the storage device 12. Since the oxygen-enriched membrane has a high resistance, the power consumption of the compression pump 10 is higher than when the air that has passed through the filter 16 is compressed. At this time, the electric power supplied to the compression pump 10 is the drive motor. 8 is regenerative electric power regenerated from the deceleration energy. In the conventional system, a part of the regenerative electric power is only used for charging the secondary battery 4, and the rest is converted into heat generated by brake braking, for example, and discarded as surplus electric power. On the other hand, according to the present fuel cell system, this surplus power can be used for the generation of oxygen-enriched gas and can be stored in the storage device 12. That is, surplus power can be converted into oxygen-enriched gas and stored without being discarded.

  When the drive motor 8 functions as a generator, the regenerative power obtained acts on the vehicle as a braking force. For this reason, when the consumption amount of the regenerative electric power in the compression pump 10 fluctuates, the braking force of the vehicle fluctuates, and acts on the occupant as a fluctuation in deceleration. The fluctuation of the deceleration causes discomfort to the occupant and deteriorates the driving performance. In particular, the fluctuation in deceleration when the vehicle speed is extremely low greatly deteriorates the driving performance at the time of stopping. Therefore, the control device 30 controls the amount of power supplied to the compression pump 10 during regeneration according to the amount of regenerative power obtained by the drive motor 8. That is, control is performed such that the larger the regenerative power amount, the larger the supplied power amount. Further, when the wheel speed detected from the rotation speed of the drive motor 8 becomes a predetermined speed or less, the valves 18, 20, and 22 are switched to the state of power running. By not operating the oxygen enrichment device 14, that is, by not sucking air through the oxygen enrichment membrane, fluctuations in the consumption of regenerative power by the compression pump 10 can be suppressed. In addition, when it is not necessary to supply the cathode gas to the fuel cell 2, the compression pump 10 may be stopped when the wheel speed becomes a predetermined speed or less.

  By the way, the storage amount of the storage device 12 has a limit. For this reason, even if the oxygen-enriched gas can be generated by using the surplus power at the time of regeneration, the surplus power converted into the oxygen-enriched gas is stored when the storage amount of the storage device 12 is limited. I ca n’t keep it. On the contrary, the amount of electric power consumed unnecessarily by the operation of the compression pump 10. Therefore, in the present fuel cell system, when the storage amount of the storage device 12 exceeds a predetermined upper limit value, the valves 18, 20, and 22 are switched to the power running state to suppress the power consumption of the compression pump 10. I am doing so. In this case, when it is not necessary to supply the cathode gas to the fuel cell 2, the compression pump 10 may be stopped.

  On the other hand, there may be a situation where the storage amount of the storage device 12 is insufficient only by generating the oxygen-enriched gas by using surplus power during regeneration. Although the use of the oxygen-enriched gas stored in the storage device 12 will be described later, if the storage amount of the storage device 12 is insufficient, the necessary amount of oxygen-enriched gas cannot be used when necessary. Therefore, in the present fuel cell system, when the storage amount of the storage device 12 falls below a predetermined lower limit value, the oxygen-enriched gas is stored in the storage device 12 even when the vehicle is powered as shown in FIG. I am doing so.

  FIG. 4 is a diagram showing the flow of the cathode gas when the storage amount of the storage device 12 falls below the lower limit value during powering of the vehicle. In this case, the three-way switching valve 18 is switched to connect the oxygen enricher 14 to the compression pump 10, and both the switching valve 20 and the switching valve 22 are opened. As a result, the oxygen-enriched gas generated by the oxygen enricher 14 is compressed by the compression pump 10, a part of which is supplied to the cathode 2 a of the fuel cell 2, and the rest is stored in the storage device 12. Here, an oxygen-enriched gas having a flow rate sufficient to obtain necessary generated power is supplied to the fuel cell 2 and the remainder is supplied to the storage device 12 for storage. Thereby, the storage amount of the storage device 12 is ensured, and the necessary amount of oxygen-enriched gas can be used when necessary. In addition, the distribution ratio of the oxygen-enriched gas supplied from the compression pump 10 to the fuel cell 2 and the oxygen-enriched gas supplied to the storage device 12 controls the duty ratios of both switching valves 20 and 22 that are electromagnetic valves. Can be adjusted.

  In addition, the secondary battery 4 is provided in the fuel cell system, but the secondary battery 4 is driven in place of the fuel cell 2 when power generation by the fuel cell 2 is not in time as in the case of sudden acceleration. It becomes a power supply source to the motor 8. For this reason, the secondary battery 4 must always be charged with a sufficient amount of power. Therefore, in the present fuel cell system, when the amount of charge (SOC) of the secondary battery 4 falls below a predetermined value, the fuel cell 2 is operated to generate power even during regeneration. That is, the valves 18, 20, and 22 are switched to the power running state to supply the cathode gas to the fuel cell 2. Thereby, the charge amount of the secondary battery 4 is ensured, and the power can be supplied from the secondary battery 4 when necessary.

  Next, utilization of the oxygen-enriched gas stored in the storage device 12 during regeneration will be described.

  When the driving motor 8 requires a large driving force, the power required by the driving motor 8 for the fuel cell 2 also increases. Here, FIG. 6 is a diagram showing the relationship between the flow rate of the cathode gas and the power consumption of the compression pump 10 required to realize it. The power generated by the fuel cell 2 can be increased by increasing the flow rate of the cathode gas. However, if the flow rate of the cathode gas is increased as shown in FIG. 6, the power consumption of the compression pump 10 is increased accordingly. Resulting in. In the present fuel cell system, the oxygen-enriched gas stored in the storage device 12 is used as means for increasing the generated power of the fuel cell 2 without increasing the power consumption of the compression pump 10.

  FIG. 5 is a diagram showing the flow of cathode gas during acceleration, for example, when the driving motor 8 requires a large driving force during powering of the vehicle, for example. At the time of acceleration, the three-way switching valve 18 is switched to connect the filter 16 to the compression pump 10, and both the switching valve 20 and the switching valve 22 are opened. Thus, the oxygen-enriched gas stored in the storage device 12 is supplied to the cathode 2a together with the air compressed by the compression pump 10 through the filter 16. The supply amount of the oxygen-enriched gas from the storage device 12 to the cathode 2a is controlled according to the required power required for the fuel cell 2. That is, the larger the required power, the larger the supply amount of the oxygen-enriched gas is set. The magnitude of the required power is calculated based on information such as the accelerator opening and the wheel speed. The supply amount can be controlled by duty control of the switching valve 20 which is an electromagnetic valve.

  FIG. 7 is a graph showing the influence of the oxygen concentration of the cathode gas on the relationship between the current density and the voltage in the fuel cell 2. As shown in this figure, at the same current density, a higher voltage can be obtained as the oxygen concentration becomes higher. In particular, as the current density becomes higher as in acceleration, the increase in oxygen concentration gives an increase in voltage. The effect is high. Therefore, as shown in FIG. 5, the oxygen-enriched gas having a high oxygen concentration is supplied from the storage device 12 to the cathode 2a, so that the power generated by the fuel cell 2 can be reduced without increasing the power consumption of the compression pump 10. It can be increased. That is, according to the present fuel cell system, it is possible to store surplus power during regeneration in the form of oxygen-enriched gas and convert it to power again for use.

  In FIG. 5, the oxygen-enriched gas is supplied from the storage device 12 to the cathode 2a, and the air compressed by the compression pump 10 by operating the compression pump 10 is also supplied to the cathode 2a. If the flow rate can be secured, the compression pump 10 may be stopped and only the oxygen-enriched gas from the storage device 12 may be supplied to the cathode 2a. FIG. 8 is a diagram showing the relationship between the flow rate of the cathode gas and the oxygen concentration required to obtain a constant generated power. The higher the oxygen concentration, the smaller the required cathode flow rate until the oxygen concentration exceeds a certain value. Become. Therefore, when the oxygen-enriched gas having a high oxygen concentration is supplied from the storage device 12, the flow rate thereof can be reduced as compared with the case where the compressed air is simply supplied from the compression pump 10.

  The oxygen-enriched gas stored in the storage device 12 can be used when the driving motor 8 requires a large driving force as described above, or when the voltage of the battery cell of the fuel cell 2 decreases. The use of is also considered. In many cases, the voltage drop of the battery cell is caused by insufficient fuel supply to the battery cell. However, if the voltage drop state is left as it is, the battery cell may burn out due to the heat generated by the battery cell itself. is there. As a voltage recovery means in such a case, it is effective to increase the supply amount of the cathode gas to the cathode 2a. However, if the rotation speed of the compression pump 10 is increased to increase the cathode flow rate, the consumption is reduced. Not only will the power increase, but there will also be a time delay before the flow rate increases. Therefore, in the present fuel cell system, when the cell voltage of the fuel cell 2 falls below a predetermined value, the oxygen-enriched gas is supplied from the storage device 12. According to this, it becomes possible to recover the voltage more quickly and without increasing the power consumption of the compression pump 10. Note that the supply amount of the oxygen-enriched gas from the storage device 12 to the cathode 2a at this time increases according to the difference between the cell voltage and the predetermined value, that is, as the difference between the cell voltage and the predetermined value increases. Set to.

  As described above, according to the present fuel cell system, when power is consumed by the drive motor 8, oxygen is not sucked through the oxygen enrichment device 14 during powering, and oxygen is generated during regeneration when the power in the system becomes redundant. Since air is sucked through the enrichment device 14 to generate the oxygen-enriched gas, the available power of the drive motor 8 is not reduced and surplus power can be used effectively. Moreover, since the generated oxygen-enriched gas is stored in the storage device 12, the surplus power is stored after being replaced with the oxygen-enriched gas, and can be used whenever necessary. That is, according to the present fuel cell system, it is possible to effectively use electric power in the entire system.

  In the first embodiment described above, the “oxygen enrichment device” of the first invention and the sixth invention is constituted by the oxygen enrichment device (oxygen enrichment film) 14, the compression pump 10, and the three-way switching valve 18. It has been realized. In the first and sixth inventions, “activate the oxygen enrichment device” means that, in the above-described first embodiment, the compression pump 10 is operated by the three-way switching valve 18 in a state where the compression pump 10 is operated. This means that the connection is switched to the oxygen enrichment device 14 side, and “stopping the operation of the oxygen enrichment device” means that the operation of the compression pump 10 is stopped or the compression pump 10 is activated. This means that the connection with the compression pump 10 by the three-way switching valve 18 is switched to the filter 16 side.

Embodiment 2. FIG.
The second embodiment of the present invention will be described below with reference to FIGS. This fuel cell system is obtained by replacing the configuration of the most upstream part of the cathode gas line with the configuration shown in FIGS. 9 and 10 in the configuration of the fuel cell system of Embodiment 1 shown in FIG. In the figure, the same reference numerals are given to the same elements as those in the first embodiment. FIG. 9 is a diagram illustrating a switching state of the valves 18, 20, and 22 when the vehicle is powering, and FIG. 10 is a diagram illustrating a switching state of the valves 18, 20, and 22 during regeneration.

  The fuel cell system of this embodiment is characterized in that two types of oxygen permeable membranes having different separation coefficients are used. As shown in FIGS. 9 and 10, the oxygen enrichment device 14 </ b> A and another oxygen enrichment device 14 </ b> B are connected to two ports other than the port connected to the compression pump 10 of the three-way switching valve 18. One oxygen enrichment device 14A has an oxygen enrichment membrane with a high separation factor of oxygen from nitrogen, and the other oxygen enrichment device 14B has an oxygen enrichment membrane with a low separation factor.

  FIG. 11 is a diagram showing the relationship between the separation coefficient and resistance (passage resistance) of the oxygen-enriched film. The larger the separation coefficient, the larger the resistance, and the smaller the separation coefficient, the smaller the resistance. Therefore, when the three-way switching valve 18 is switched to the oxygen enrichment device 14A side having an oxygen enriched membrane with a high separation coefficient, the power consumption of the compression pump 10 is increased, but a high concentration oxygen enriched gas is obtained. be able to. Conversely, when the three-way switching valve 18 is switched to the oxygen enrichment device 14B side having an oxygen enriched membrane with a low separation coefficient, a high concentration oxygen enriched gas cannot be obtained, but the consumption of the compression pump 10 The power can be reduced.

  In this fuel cell system, at the time of regeneration, as shown in FIG. 10, the three-way switching valve 18 is switched so as to connect the oxygen enriching device 14A having an oxygen enriched membrane having a high separation coefficient to the compression pump 10, and the switching valve 20 is opened and the switching valve 22 is closed. Thereby, like Embodiment 1, high concentration oxygen-enriched gas is compressed by the compression pump 10 and stored in the storage device 12. On the other hand, at the time of power running, as shown in FIG. 9, the three-way selector valve 18 is switched to connect the oxygen enricher 14B having an oxygen enriched membrane with a low separation coefficient to the compression pump 10, and the selector valve 20 is closed. The switching valve 22 is opened. Thereby, it is possible to supply the fuel cell 2 with a cathode gas having a higher oxygen concentration than in the case of the first embodiment while suppressing an increase in power consumption of the compression pump 10.

  As described above, according to the present fuel cell system, the two types of oxygen permeable membranes having different separation coefficients are provided, and the connection with the compression pump 10 is switched according to the situation. The power generation efficiency of the fuel cell 2 can be further improved while enabling effective use of the power. In addition, although switching of each valve 18, 20, and 22 at the time of power running and regeneration was demonstrated here, if switching of each valve 18, 20, and 22 in another condition is performed similarly to Embodiment 1. FIG. Good.

  In the second embodiment described above, the “oxygen enrichment device” of the first invention and the sixth invention is constituted by the oxygen enrichment device (oxygen enrichment film) 14A, the compression pump 10, and the three-way switching valve 18. It has been realized. In the first and sixth inventions, “activate the oxygen enrichment device” means that, in the above-described second embodiment, the compressor pump 10 is operated by the three-way switching valve 18 in a state where the compression pump 10 is operated. This means that the connection is switched to the oxygen enrichment device 14A side, and “stopping the operation of the oxygen enrichment device” means that the operation of the compression pump 10 is stopped or the compression pump 10 is activated. This means that the connection with the compression pump 10 by the three-way switching valve 18 is switched to the oxygen enrichment device 14B side.

Others.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above-described embodiment, a membrane separation type apparatus is used as the oxygen enrichment apparatus, but the oxygen enrichment apparatus according to the present invention is not limited to the membrane separation type. That is, any oxygen-enriching device that operates by supplying electric power may be used. For example, a magnetic field type device as described in Patent Document 1 or a known pressure swing type separation device may be used.

It is a figure which shows schematic structure of the fuel cell system as Embodiment 1 of this invention. It is a figure which shows the flow of the cathode gas at the time of power running in the system of FIG. It is a figure which shows the flow of the cathode gas at the time of regeneration in the system of FIG. It is a figure which shows the flow of the cathode gas when the storage amount of a storage device falls below a lower limit at the time of power running in the system of FIG. It is a figure which shows the flow of the cathode gas at the time of acceleration in the system of FIG. It is a figure which shows the relationship between the flow volume of cathode gas, and the power consumption of the compression pump required to implement | achieve it. It is a figure which shows about the influence which the oxygen concentration of cathode gas has on the relationship between the current density and voltage in a fuel cell. It is a figure which shows the relationship between the flow volume of the cathode gas required for obtaining fixed electric power generation, and oxygen concentration. It is a figure which shows the flow of the cathode gas at the time of power running in the fuel cell system as Embodiment 2 of this invention. It is a figure which shows the flow of the cathode gas at the time of regeneration in the fuel cell system as Embodiment 2 of this invention. It is a figure which shows the relationship between the separation coefficient of oxygen enrichment membrane, and passage resistance.

Explanation of symbols

2 Fuel cell 2a Cathode 4 Secondary battery 6 Inverter 8 Drive motor 10 Compression pump 12 Storage device 14 Oxygen enrichment device (oxygen enrichment membrane)
14A oxygen enrichment device (oxygen enrichment membrane with high separation factor)
14B oxygen enricher (low separation factor oxygen enriched membrane)
16 Filter 18 Three-way switching valve 20, 22 Switching valve 30 Control device

Claims (9)

A fuel cell that generates electricity by supplying an anode gas containing hydrogen and a cathode gas containing oxygen;
A motor operated by electric power,
An oxygen enrichment device disposed in a supply system of a cathode gas to the fuel cell and operating with electric power to generate an oxygen enriched gas;
Control means for controlling the operating state of the oxygen enricher,
The fuel cell system, wherein the control means supplies surplus power in the system that is not consumed by the motor to the oxygen enricher.   2. The fuel cell system according to claim 1, further comprising storage means for storing the oxygen-enriched gas generated by the oxygen-enriching device.   3. The fuel cell system according to claim 2, wherein oxygen-enriched gas is supplied from the storage unit to the fuel cell when the generated power of the fuel cell is insufficient with respect to the required power.   3. The fuel cell according to claim 2, wherein the control means operates the oxygen enricher regardless of a surplus state of electric power in the system when the storage amount of the storage means is equal to or less than a predetermined value. system.   The fuel according to any one of claims 2 to 4, wherein the control means stops the operation of the oxygen enricher under a predetermined condition regardless of a surplus state of electric power in the system. Battery system. In a fuel cell system mounted on a vehicle,
A fuel cell that generates electricity by supplying an anode gas containing hydrogen and a cathode gas containing oxygen;
An oxygen enrichment device disposed in a supply system of cathode gas to the fuel cell and operating with electric power to generate an oxygen enriched gas;
Storage means for storing the oxygen-enriched gas produced by the oxygen-enriching device;
A drive motor that operates with electric power to drive the vehicle;
Regenerative means for regenerating deceleration energy of the vehicle as electric power;
Control means for controlling the operating state of the oxygen enricher;
Line switching means for switching the cathode gas supply line in the system,
During powering by the drive motor, the operation of the oxygen enrichment device is stopped by the control means, and the supply line is switched by the line switching means so that cathode gas is supplied to the fuel cell,
At the time of regeneration by the regeneration means, the oxygen enrichment apparatus is operated by the control means, and the line switching means allows the oxygen enriched gas generated by the oxygen enrichment apparatus to be stored in the storage means. A fuel cell system, wherein a supply line is switched.   The supply line is switched by the line switching means so that oxygen-enriched gas is supplied from the storage means to the fuel cell when the power generated by the fuel cell is insufficient with respect to the required power. The fuel cell system according to claim 6.   When the storage amount of the storage means is equal to or less than a predetermined value, the oxygen enrichment device is operated by the control means regardless of the driving state of the vehicle, and the oxygen enrichment generated by the oxygen enrichment device 7. The fuel cell system according to claim 6, wherein the supply line is switched by the line switching means so that at least a part of the gas is stored in the storage means. 9. The fuel cell system according to claim 6, wherein the operation of the oxygen enrichment device is stopped by the control unit under a predetermined condition regardless of an operation state of the vehicle. .

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