JP2007328933A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make constitution suitable from the standpoint of achieving simple constitution and efficient heat supply while keeping performance and function of a heater or a heat storage means. <P>SOLUTION: A fuel cell system is equipped with a fuel cell 2 generating electric power by the electrochemical reaction of reaction gasses; a coolant circulation passage 41 circulating a coolant between the fuel cell 2 and a radiator 43; the heat storage means 46 installed in the coolant circulation passage 41; and a heat exchanger 46a for heating and a heater 46b for heating installed inside the heat storage means 46. The coolant circulation passage 41 has a bypass passage 44 bypassing the radiator 43, and preferably, the heat storage means 46 is installed in the bypass passage 44. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system. More specifically, the present invention relates to an improvement in a fuel cell cooling system in a fuel cell system.

Conventionally, as a fuel cell system, a fuel cell cooling system including a refrigerant circulation channel, a radiator, a pump, and the like is generally provided, and a refrigerant is circulated to cool the fuel cell stack. A fuel cell system having a configuration in which such a refrigerant circulation channel is provided with a bypass channel that passes through a heat storage means with a heater is also known (see, for example, Patent Document 1).
JP 2005-93117 A

  However, in the fuel cell system as described above, since the heat stored in the heat storage means is used only for warming up the fuel cell, for example, when heating is additionally provided, a heating heat medium is separately provided. It was necessary to prepare for. For example, it is not always preferable to separately prepare a heating medium for heating in this way from the viewpoint of simplification of the configuration. Also, it is not preferable from the viewpoint of efficient heat supply in the entire system.

  Accordingly, an object of the present invention is to provide a fuel cell system having a suitable configuration from the viewpoint of simplifying the configuration and increasing the efficiency of heat supply while maintaining the performance and function of the heater and the heat storage means.

  In order to solve this problem, the present inventor has made various studies. For example, in the case of a fuel cell vehicle (FCHV) equipped with a fuel cell, the fuel cell cooling system may be provided with devices such as an electric heater, an air conditioner heater, and a hot water pot. The use of each device in this case is, for example, for an electric heater, to maintain the temperature in the fuel cell stack after a freezing point breakage at a low temperature startup, for a heater for an air conditioner, to secure a heat source for heating, and for a hot water pot to stop processing This includes shortening the drying time of the electrolyte membrane in the fuel cell and increasing the temperature in the stack during the startup process. Of course, there are various uses and purposes of each device as described above, but the present inventor who paid attention to the function has led to a new idea that leads to the solution of the problem as a result of further studies.

  The fuel cell system of the present invention is based on such an idea, and is a fuel cell that generates electricity by an electrochemical reaction of a reaction gas, and a refrigerant circulation that circulates a refrigerant between the fuel cell and a radiator to cool the fuel cell. It is characterized by comprising a flow path, a heat storage means provided in the refrigerant circulation flow path, and a heating heat exchanger and a heater provided in the heat storage means.

  In the case of this fuel cell system, heat can be stored in the heat storage means provided in the fuel cell cooling system (refrigerant circulation passage). In addition, a heat exchanger for heating and a heater for heating are provided in the heat storage means, and the stored heat can be used as a heat source for the heat exchanger for heating and the heater for heating. According to this, for example, the heat of the heat storage means that can be heated by the heater can be used for warming up and air-conditioning of the fuel cell. Heat can be efficiently distributed to both batteries and air conditioning.

  Moreover, in the fuel cell system according to the present invention, the refrigerant circulation passage includes a bypass passage that bypasses the radiator, and the heat storage means is provided in the bypass passage. For example, when warming up at a low temperature, it is possible to speed up the warming by separating the radiator and circulating the refrigerant. Moreover, since the heat storage means is provided with a heat exchanger for heating, when the heat generated by the fuel cell and the heat consumed by the heating are balanced, the heat can be used efficiently without driving the radiator. Therefore, energy saving can be realized.

  Furthermore, when the fuel cell is activated, when there is a heating request, it is preferable to control the output of the heater based on the heating request and the heating request of the fuel cell. According to this, since heat of both the fuel cell and the heating can be generated using one heater and heat exchange is performed in the same heat storage means, the heat of the heater is one side (for example, only the fuel cell, Alternatively, heat can be supplied uniformly without being biased to heating only).

  It is also preferable to supply heat at a temperature exceeding the temperature of the refrigerant flowing through the refrigerant circulation channel by heating the refrigerant using the heater.

  According to the present invention, it is possible to simplify the configuration of the heater and the heat storage means in the fuel cell cooling system, and it is also possible to supply heat more efficiently. Moreover, it is possible to achieve simplification and efficiency while maintaining the performance and function of these heaters and heat storage means.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 3 show an embodiment of a fuel cell system according to the present invention. The fuel cell system 1 of the present embodiment includes a fuel cell 2 that generates power by an electrochemical reaction of a reaction gas, and a refrigerant circulation channel that cools the fuel cell 2 by circulating a refrigerant between the fuel cell 2 and the radiator 43. 41, a heat storage means 46 provided in the refrigerant circulation passage 41, and a heating heat exchanger and a heating heater provided in the heat storage means 46. With such a configuration, The configuration of the refrigerant piping system 5 is simplified and the efficiency of heat supply is improved (see FIGS. 1 and 2).

  In the following, the overall configuration of the fuel cell system 1 will be described first, and then the detailed configuration of the refrigerant piping system 5 in such a fuel cell system 1 will be described.

  FIG. 1 shows a schematic configuration of a fuel cell system 1 in the present embodiment. As shown in the figure, a fuel cell system 1 includes a fuel cell 2, an oxidizing gas supply / discharge system (hereinafter also referred to as an oxidizing gas piping system) 3 for supplying air (oxygen) as an oxidizing gas to the fuel cell 2, a fuel A fuel gas supply / discharge system (hereinafter also referred to as a fuel gas piping system) 4 for supplying hydrogen as a gas to the fuel cell 2, a refrigerant piping system 5 for supplying a refrigerant to the fuel cell 2 and cooling the fuel cell 2, A power system 6 that charges and discharges system power and a control unit 7 that performs overall control of the entire system are provided.

  The fuel cell 2 is formed of, for example, a solid polymer electrolyte type and has a stack structure in which a large number of single cells are stacked. A single cell of the fuel cell 2 has an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and a pair of separators so as to sandwich the air electrode and the fuel electrode from both sides. have. The fuel gas is supplied to the fuel gas flow path of one separator and the oxidizing gas is supplied to the oxidizing gas flow path of the other separator, and the fuel cell 2 generates electric power by this gas supply.

  The oxidizing gas piping system 3 has a supply path 11 through which the oxidizing gas supplied to the fuel cell 2 flows, and a discharge path 12 through which the oxidizing off gas discharged from the fuel cell 2 flows. The supply path 11 is provided with a compressor 14 that takes in the oxidizing gas via the filter 13, and a humidifier 15 that humidifies the oxidizing gas fed by the compressor 14. The oxidizing off-gas flowing through the discharge path 12 is subjected to moisture exchange by the humidifier 15 through the back pressure regulating valve 16, and is finally exhausted into the atmosphere outside the system as exhaust gas. The compressor 14 takes in the oxidizing gas in the atmosphere by driving the motor 14a.

  The fuel gas piping system 4 includes a hydrogen supply source 21, a supply path 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 2 flows, and a supply path for supplying hydrogen offgas (fuel offgas) discharged from the fuel cell 2. 22, a circulation path 23 for returning to the junction point A of 22, a pump 24 that pumps the hydrogen off-gas in the circulation path 23 to the supply path 22, and a discharge path 25 that is branched and connected to the circulation path 23. .

  The hydrogen supply source 21 is composed of, for example, a high-pressure tank or a hydrogen storage alloy, and is configured to be able to store, for example, 35 MPa or 70 MPa of hydrogen gas. When the main valve 26 of the hydrogen supply source 21 is opened, hydrogen gas flows out into the supply path 22. The hydrogen gas is finally depressurized to about 200 kPa, for example, by the pressure regulating valve 27 and other pressure reducing valves, and supplied to the fuel cell 2.

  A shutoff valve 28 is provided on the upstream side of the junction point A of the supply path 22. The hydrogen gas circulation system is configured by sequentially communicating a flow path downstream from the confluence point A of the supply path 22, a fuel gas flow path formed in the separator of the fuel cell 2, and the circulation path 23. Yes. The hydrogen pump 24 circulates and supplies hydrogen gas in the circulation system to the fuel cell 2 by driving the motor 24a.

  The discharge path 25 is provided with a purge valve 33 that is a shut-off valve. By appropriately opening the purge valve 33 when the fuel cell system 1 is operating, impurities in the hydrogen off gas are discharged together with the hydrogen off gas to a hydrogen diluter (not shown). By opening the purge valve 33, the concentration of impurities in the hydrogen off-gas in the circulation path 23 decreases, and the concentration of hydrogen in the hydrogen off-gas supplied in circulation increases.

  The refrigerant piping system 5 includes a refrigerant circulation channel 41 communicating with the cooling channel in the fuel cell 2, a cooling pump 42 provided in the refrigerant circulation channel 41, and a radiator that cools the refrigerant discharged from the fuel cell 2. 43, a bypass passage 44 that bypasses the radiator 43, and a three-way valve (switching valve) 45 that sets the flow of cooling water to the radiator 43 and the bypass passage 44. The cooling pump 42 circulates and supplies the refrigerant in the refrigerant circulation passage 41 to the fuel cell 2 by driving the motor 42a.

  The power system 6 includes a high-voltage DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, and various auxiliary inverters 65, 66, and 67. The high-voltage DC / DC converter 61 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 62 and outputs it to the traction inverter 63 side, and the direct-current input from the fuel cell 2 or the traction motor 64. And a function of adjusting the voltage and outputting it to the battery 62. The charge / discharge of the battery 62 is realized by these functions of the high-voltage DC / DC converter 61. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 61.

  The battery 62 is configured such that battery cells are stacked and a constant high voltage is used as a terminal voltage, and surplus power can be charged or power can be supplementarily supplied under the control of a battery computer (not shown). The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 is, for example, a three-phase AC motor, and constitutes, for example, a main power source of a vehicle on which the fuel cell system 1 is mounted.

  The auxiliary machine inverters 65, 66, and 67 are electric motor control devices that control driving of the corresponding motors 14a, 24a, and 42a, respectively. Auxiliary machine inverters 65, 66, and 67 convert a direct current into a three-phase alternating current and supply it to motors 14a, 24a, and 42a, respectively. Auxiliary machine inverters 65, 66, and 67 are, for example, pulse width modulation type PWM inverters, which convert a DC voltage output from fuel cell 2 or battery 62 into a three-phase AC voltage in accordance with a control command from control unit 7. The rotational torque generated by each motor 14a, 24a, 42a is controlled.

  The control unit 7 is configured as a microcomputer including a CPU, a ROM, and a RAM inside. The CPU executes a desired calculation according to the control program, and performs various processes and controls such as a thawing control of the pump 24 described later. The ROM stores control programs and control data processed by the CPU. The RAM is mainly used as various work areas for control processing. The control unit 7 inputs detection signals such as various pressure sensors, temperature sensors, and outside air temperature sensors used in the gas system (3, 4) and the refrigerant piping system 5, and outputs control signals to each component.

  Next, a characteristic structure of the fuel cell system 1 according to the present invention, more specifically, a structure in the refrigerant piping system 5 will be described (see FIG. 2 and the like). Hereinafter, a case where the fuel cell system 1 is mounted on a fuel cell vehicle will be described, but the application range of the fuel cell system 1 according to the present invention is not limited to such a fuel cell vehicle.

  As described above, the fuel cell system 1 according to the present embodiment has a refrigerant that cools the fuel cell 2 by circulating the refrigerant (for example, the cooling system LLC) between the fuel cell 2 and the radiator 43 in the refrigerant piping system 5. The circulation channel 41, the heat storage means 46, a heating heat exchanger, and a heating heater are provided.

  The heat storage means 46 is for making it possible to use the heat stored in the refrigerant piping system 5 as a heat source in other devices as necessary. For example, the heat storage means 46 of the present embodiment is disposed in the middle of the bypass flow path 44 and can exchange heat with the refrigerant flowing through the bypass flow path 44 (see FIG. 2). .

  The heat storage means 46 is configured as a warming / warming device integrated by a hot water pot or a hot water tank with a built-in electric heater. Both functions can be demonstrated. For example, in the case of this embodiment, this heat storage means 46 is comprised by the warm water pot 46a arrange | positioned in the middle of the bypass flow path 44, and the heater 46b for heating incorporated in this warm water pot 46a (refer FIG. 2). .

  The hot water pot 46a is a container that stores heat by temporarily storing hot water (in the case of the present embodiment, a coolant such as cooling water that is heated by receiving heat from the fuel cell 2 in this embodiment). The hot water pot 46a itself may be a known one, and for example, a hot water pot (see reference numeral 461 in FIG. 2) that has been used can be used. Moreover, the capacity | capacitance and shape of a container are not specifically limited, Based on the specification and structure of the said fuel cell system 1, it can determine suitably. The hot water pot 46a of the present embodiment is provided so as to be able to supply heat to the in-vehicle air conditioner 8, and can exhibit the same function as the air conditioner heater (see reference numeral 463 in FIG. 2) that has been used. Specifically, for example, when the heating performance of the air conditioner 8 is insufficient only by performing normal heat exchange with the outside air, such as when traveling at low temperatures, heat is generated between the hot water pot 46a and the refrigerant (hot water). By performing the exchange, it can function as a heat exchanger for heating (see FIG. 2).

  The heater 46b is an electric heater built in the hot water pot 46a. For example, the heating heater 46b of the present embodiment is provided so as to generate heat when power is supplied from the battery 62 via the high-voltage DC / DC converter 61, and heats the refrigerant in the hot water pot 46a. A function similar to that of the electric heater (see reference numeral 462 in FIG. 2) can be exhibited. Specifically, for example, the heating heater 46b is used in a situation where the temperature inside the fuel cell stack that has exceeded the freezing point is maintained by raising the temperature when the fuel cell 2 is started or after the starting point. In the present embodiment, an electric heater is illustrated, but this is only an example of a suitable heater, and other various heaters can be applied.

  In addition, the fuel cell system 1 in the present embodiment further includes an ion exchanger 47, an air compressor 48, and an intercooler 49 in the refrigerant piping system 5 (see FIG. 2). The ion exchanger 47 removes impurities in the circulating refrigerant by adsorbing ions, and suppresses corrosion of the metal and deterioration of the function of the fuel cell 2. The air compressor 48 compresses the air taken in from the outside, and the intercooler 49 cools the air that has been compressed to a high temperature. In the case of this embodiment, another flow paths 41a and 41b parallel to the above-described bypass flow path 44 are provided, an ion exchanger 47 is provided in one flow path 41a, and an air compressor 48 and an intercooler 49 are provided in the other flow path 41b. Are arranged (see FIG. 2).

  The heat storage means 46 of this embodiment can act or function as follows when the operation is stopped or started when the fuel cell vehicle is mounted, for example.

  That is, as described above, by incorporating the heater 46b in the hot water pot 46a, the heat storage means 46 having a structure in which the heat retaining device and the warming device are integrated, the function of storing hot water and the inside It can exhibit both functions of generating heat. For example, when the operation of the fuel cell 2 is stopped, the scavenging time is shortened by drying the electrolyte membrane of each cell in the fuel cell 2 earlier during the scavenging process for discharging the moisture in the fuel cell 2 to the outside. Is possible. Further, when the fuel cell 2 is activated, it is possible to perform a process in which warm water is poured into the fuel cell stack immediately before the activation process to increase the temperature in the stack. According to this, for example, when starting below freezing, it is possible to break through the freezing point earlier than usual by preheating so that it is possible to start up in a state where the freezing point has been broken in advance. Time can be shortened. Further, at the time of startup, it is possible to further shorten the time required for the startup process by performing rapid warm-up by low-efficiency operation.

  Here, the quick warm-up by the low efficiency operation is briefly described as follows. That is, the low-efficiency operation is an operation in which an operating point is brought into a region where the power generation efficiency is low, and the input hydrogen energy is converted into heat correspondingly. During normal operation, the IV characteristic (current-voltage characteristic) is as shown by a solid line in FIG. 3, but is shown by a broken line by limiting the air stoichiometric ratio and causing a voltage drop due to concentration overvoltage, for example. It is possible to change to such a low efficiency operation state and shift the operating point by the change. In such a case, although the power generation efficiency is inferior, the amount of heat generation can be increased correspondingly and used for rapid warm-up (see FIG. 3).

  Further, for example, when the fuel cell 2 is activated below the freezing point and there is a heating request to the air conditioner 8, the output of the heater 46b is controlled based on the heating request (warming-up request) of the fuel cell 2 and the heating request. It is preferable. According to the fuel cell system 1 of the present embodiment, not only can the heat that can be supplied to both the fuel cell 2 and the heating be generated using a single heater, but also inside the single heat storage means 46. Since the heat exchange is performed, the heat of the heater for heating 46b can be supplied uniformly without being consumed in the fuel cell 2 or the heating. For example, if there is a heating request at the time of starting below freezing as described above, it is possible to simultaneously and quickly perform both warm-up and heating by increasing the output of the heater 46b.

  Furthermore, since the fuel cell system 1 of the present embodiment includes the bypass flow path 44 that bypasses the radiator 43, for example, when starting or warming up at low temperatures, the radiator 43 is disconnected and the refrigerant is circulated. It is also preferable that In this way, warm-up can be further accelerated.

  As described so far, according to the fuel cell system 1 of the present embodiment, the fuel having a preferable configuration from the viewpoint of simplification of the configuration and efficiency of heat supply while maintaining the performance and function of the heater, the heat storage device, and the like. The battery system 1 can be constructed. In other words, since the heat storage means 46 is a form in which heating and heating functions are integrally added to a pot that previously had only a heat retaining function, for example, when there is a margin in SOC (State of Charge), It is possible to store heat using the pot 46a. In short, it is possible to construct a novel heating / warming device that does not lose the performance and function of the fuel cell 2 and the heating air conditioner 8 that both require heat at the same time.

  Also, according to the fuel cell system 1 of the present embodiment, it becomes possible to supply heat at a temperature exceeding the refrigerant temperature in the operating state, so that the scavenging time when the operation is stopped can be shortened, or warm air using preheating can be reduced. It is preferable in that it can reduce the chance of starting below freezing. For example, even in an atmosphere of −5 ° C., the fuel cell 2 is preheated using the heat storage means 46 and then started, so that the start-up opportunity is low when the stack temperature is below freezing. Become.

  In addition, if the SOC has a margin as described above, heat is stored in the heat storage means 46. In addition, for example, when the battery 62 cannot accept regenerative power (when fully charged), the heat storage means. The fuel consumption of the fuel cell vehicle can be improved by storing heat in 46. In this case, further improvement can be achieved if charge / discharge control of the battery 62 is also performed when the vehicle is stopped or started.

  Further, for example, if the conventional electric heater (462) and the air conditioner heater (463) are simply integrated, most of the heat generated by these heaters at the time of low temperature start-up or running is transferred to the fuel cell 2. May be consumed and the contribution to the heating function may be greatly reduced. In this respect, in this embodiment, since the heat retaining function is integrated with the apparatus having the warming / heating function, heat supply can be appropriately distributed between the fuel cell 2 and the air conditioner 8. Therefore, if the fuel cell vehicle described in the present embodiment is used, for example, it is possible to obtain a heat supply for heating even at the time of starting below freezing. It is preferable in that it can be obtained.

  Moreover, according to the heat storage means 46 of the present embodiment in which the devices that have been individually constructed are integrated, the configuration of the heater and the heat storage device in the fuel cell cooling system (refrigerant piping system 5) is simplified. It becomes possible. In addition, this device is advantageous in terms of downsizing and weight reduction, and a compact configuration is also possible.

  In addition, the heat storage means 46 as in the present embodiment is preferable from the viewpoint of energy saving. As described above, since the heat storage means 46 has the hot water pot (heat exchanger for heating) 46a, for example, when the heat generated in the fuel cell 2 and the heat consumed by the heating are balanced, It is also possible to efficiently use heat without driving the radiator 43. When such an operation state is constructed in the fuel cell system 1, it is possible to save energy by suppressing power consumption.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the case where the present invention is applied to a fuel cell vehicle (FCHV; Fuel Cell Hybrid Vehicle) equipped with the fuel cell 2 or its in-vehicle power generation system has been described. The present invention can be applied to a self-propelled body such as a body (for example, a ship or an airplane) or a robot, and further can be applied as a stationary fuel cell system.

It is a figure which shows the structure of the fuel cell system in this embodiment. It is a figure which shows an example of a structure of a fuel cell cooling system (refrigerant piping system). It is a graph which shows an example of an IV characteristic curve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 41 ... Refrigerant circulation flow path, 43 ... Radiator, 44 ... Bypass flow path, 46 ... Heat storage means, 46a ... Hot water pot (heat exchanger for heating), 46b ... Heating heater

Claims (4)

A fuel cell that generates electricity by an electrochemical reaction of the reaction gas; and
A refrigerant circulation passage for circulating the refrigerant between the fuel cell and the radiator to cool the fuel cell;
Heat storage means provided in the refrigerant circulation flow path;
A heating heat exchanger and a heating heater provided in the heat storage means;
A fuel cell system comprising:   2. The fuel cell system according to claim 1, wherein the refrigerant circulation passage includes a bypass passage that bypasses the radiator, and the heat storage unit is provided in the bypass passage. 3.   2. The fuel cell system according to claim 1, wherein when the fuel cell is activated, when there is a heating request, the output of the heater is controlled based on the heating request of the fuel cell and the heating request.   The fuel cell according to any one of claims 1 to 3, wherein heat of a temperature exceeding a refrigerant temperature flowing through the refrigerant circulation passage is supplied by heating the refrigerant using the heater for heating. system.

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