JP2007280715A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of preventing system freezing caused by produced water without excessively complicating system constitution and without limiting using fuel gas to low freezing point alcohol-based hydrocarbon. <P>SOLUTION: A connection passage 41 connecting an oxidant gas passage 31 and a cooling liquid passage 21 is installed, and antifreeze in the cooling liquid passage 21 is made to flow to the gas passage through the connection passage 41. Therefore, the oxidant gas passage 31 does not freeze thanks to the antifreeze. Since freezing is prevented by the antifreeze, fuel gas is not limited to low freezing point alcohol-based hydrocarbon such as methanol. To prevent freezing, only the connection passage 41 and peripheral components 42, 43 are additionally required, and addition of a methanol tank or a methanol supply device is unnecessary. Excess complication of system constitution can be avoided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

Conventionally, a methanol tank that stores methanol, which is a raw fuel for generating fuel gas to be supplied to the fuel cell, an oxidation exhaust gas path through which the oxidation exhaust gas discharged from the fuel cell flows, and the methanol tank and the oxidation exhaust gas path are connected. A fuel cell system including a methanol addition path is known. In this fuel cell system, methanol is supplied into the oxidation exhaust gas passage through the methanol addition passage, and methanol is mixed with the product water condensed in the oxidation exhaust gas passage. By mixing methanol with the produced water in this way, the melting point of the produced water is lowered, and even when the outside air temperature is lowered during the shutdown of the fuel cell, the oxidation exhaust gas path is prevented from freezing due to the produced water being frozen. (For example, refer patent document 1).
JP-A-10-223249

  However, in the conventional fuel cell system, the fuel gas needs to be a low freezing point alcohol hydrocarbon such as methanol, and in the fuel cell system using pure hydrogen as the fuel gas, a methanol tank, a methanol supply device, etc. are separately mounted. There is a need. In addition, the conventional fuel cell system has a complicated system configuration. As a result, the number of parts is large, the cost is increased, and the system volume is increased.

  The present invention has been made in order to solve such a conventional problem. The object of the present invention is to prevent the system configuration from being greatly complicated, and the fuel gas used is a low freezing point alcohol hydrocarbon. However, the present invention is to provide a fuel cell system capable of preventing system freezing due to generated water.

  The fuel cell system of the present invention includes a fuel cell, a coolant flow path, a gas flow path, a connection flow path, and a control means. The fuel cell reacts with the supplied gas to generate electric power, and the coolant flow path becomes a flow path for circulating the antifreeze liquid. The gas channel is a channel through which the supply gas supplied to the fuel cell and the gas discharged from the fuel cell flow, and the connection channel connects the gas channel and the coolant channel. The control means causes the antifreeze liquid in the coolant flow path to flow into the gas flow path via the connection flow path.

  According to the present invention, the connecting channel that connects the gas channel and the coolant channel is provided, and the antifreeze liquid in the coolant channel is caused to flow into the gas channel via the connecting channel. In this way, since the antifreeze liquid flows into the gas flow path, the gas flow path is not frozen by freezing of the generated water. In particular, since freezing is prevented by the antifreeze liquid, the fuel gas is not limited to low freezing point alcohol hydrocarbons such as methanol, and freezing can be prevented. Furthermore, in order to prevent freezing, it is only necessary to add the connection flow path and its surrounding parts to the fuel cell system, and it is not necessary to add a methanol tank, a methanol supply device, or the like separately. Therefore, the system configuration is not greatly complicated. Therefore, the system configuration can be prevented from becoming very complicated, and the fuel gas to be used is not limited to the low freezing point alcohol hydrocarbons, and the system freezing by the generated water can be prevented.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a fuel cell system according to a first embodiment of the present invention. As shown in the figure, the fuel cell system 1 includes a fuel cell 10, a coolant circulation system 20, an oxidant gas supply system 30, an antifreeze liquid movement system 40, and a controller (control means) 50. .

  The fuel cell 10 includes a fuel electrode that receives supply of fuel gas (hydrogen gas) and an oxidant electrode that receives supply of oxidant gas (oxygen). The fuel cell 10 includes supply of the supplied fuel gas and oxidant gas. It generates electricity by reacting gas. Further, the fuel electrode and the oxidant electrode are overlapped with an electrolyte membrane interposed therebetween to constitute a power generation cell, and the fuel cell 10 has a stack structure in which a plurality of layers of these power generation cells are stacked.

  The coolant circulation system 20 is for suppressing the temperature so that the temperature of the fuel cell 10 does not become too high. The coolant circulation system 20 includes a coolant flow path 21, a radiator 22, a reservoir tank 23, and a pump (coolant circulation means) 24. The coolant flow path 21 serves as a flow path for circulating an antifreeze liquid (for example, an ethylene glycol aqueous solution or an insulating oil such as silicon oil) in the coolant circulation system 20, and the antifreeze liquid is a fuel cell 10, a radiator 22, a reservoir tank. 23 and the pump 24 in this order, and flows into the fuel cell 10 again. The radiator 22 is for cooling the antifreeze liquid by heat exchange with the outside air. The reservoir tank 23 stores an excess amount of the antifreeze liquid. The pump 24 serves as a circulation source for circulating the antifreeze liquid in the coolant flow path 21.

  The oxidant gas supply system 30 includes an oxidant gas flow path (gas flow path) 31, a compressor (gas supply means) 32, and a switching valve 33. The oxidant gas flow path 31 is a flow path through which the oxidant gas of the supply gas supplied to the fuel cell 10 flows. Further, the oxidant gas flow path 31 is a channel through which the cathode off-gas discharged from the fuel cell 10 flows. The compressor 32 is provided in the oxidant gas flow path 31 and supplies supply gas to the fuel cell 10, and has a structure in which air is compressed and sent to the oxidant electrode of the fuel cell 10. The switching valve 33 is provided in the oxidant gas flow path 31 on the upstream side of the compressor 32 and opens or closes the oxidant gas flow path 31 by opening and closing.

  The antifreeze liquid moving system 40 is configured to cause the antifreeze liquid in the coolant circulation system 20 to flow into the oxidant gas supply system 30 and return the antifreeze liquid that has flowed into the oxidant gas supply system 30 to the coolant circulation system 20. The antifreeze liquid movement system 40 includes a connection channel 41, a first connection channel valve (connection channel valve) 42, and a second connection channel valve (connection channel valve) 43. The connection channel 41 connects the coolant channel 21 and the oxidant gas channel 31. One end of the connection channel 41 is connected to the coolant channel 21 in the section from the fuel cell 10 to the radiator 22, and the other end is connected to the oxidant gas channel 31 on the downstream side of the fuel cell 10. Yes. The first connection channel valve 42 is provided at one end side of the connection channel 41, that is, at a connection portion between the coolant channel 21 and the connection channel 41. The first connection flow path valve 42 is constituted by a three-way valve, and is configured to connect or block the coolant flow path 21 and the connection flow path 41. The second connection flow path valve 43 is provided at the other end side of the connection flow path 41, that is, at the connection portion between the oxidant gas flow path 31 and the connection flow path 41. The second connection flow path valve 43 is constituted by a three-way valve, and is configured to communicate or block the oxidant gas flow path 31 and the connection flow path 41. Moreover, these connection path | route valves 42 and 43 can adjust the flow volume of the antifreezing liquid which flows into the connection flow path 41 by adjusting an opening degree.

  The controller 50 controls the entire fuel cell system 1. In this embodiment, the controller 50 particularly controls the rotational speeds of the pump 24 and the compressor 32, the opening and closing of the switching valve 33, and the opening degrees of the connection path valves 42 and 43. It has a configuration. The controller 50 controls the opening degree of the connection path valves 42 and 43 so that the antifreeze liquid in the coolant flow path 21 flows into the oxidant gas flow path 31 via the connection flow path 41.

  Here, the fuel cell 10 generates water by power generation. This generated water may accumulate in the oxidant gas flow path 31, and when the fuel cell system 1 is stopped in a low temperature environment, the generated water may freeze and freeze the oxidant gas flow path 31.

  However, in the present embodiment, the controller 50 causes the antifreeze liquid to flow into the oxidant gas flow path 31. As a result, the oxidant gas flow path 31 is not frozen by the antifreeze liquid even if the produced water exists. In particular, since freezing is prevented by the antifreeze liquid, the fuel gas is not limited to low freezing point alcohol hydrocarbons such as methanol, and freezing can be prevented. Furthermore, in order to prevent freezing, it is only necessary to add the connection flow path and its surrounding parts to the fuel cell system, and it is not necessary to add a methanol tank, a methanol supply device, or the like separately. Therefore, the system configuration is not greatly complicated.

  In the fuel cell system 1, the total volume of the coolant channel 21 and the reservoir tank 23 is preferably larger than the volume of the oxidant gas channel 31. This is because the oxidant gas channel 31 can be filled with the antifreeze liquid, and freezing can be further prevented.

  Next, an outline of the operation of the fuel cell system 1 according to the present embodiment will be described. FIG. 2 is a flowchart showing the operation of the fuel cell system 1 according to the first embodiment, and shows the operation when the fuel cell system 1 is stopped.

  First, it is assumed that the pump 24 and the compressor 32 of the fuel cell system 1 are in an operating state. When a system stop signal is input as shown in FIG. 2 (ST1), the controller 50 stops the compressor 32 (ST2). Next, the controller 50 closes the switching valve 33 (ST3).

  And the controller 50 controls the 1st connection flow path valve 42, and connects the coolant flow path 21 and the connection flow path 41 (ST4). Further, the controller 50 controls the second connection flow path valve 43 to connect the oxidant gas flow path 31 and the connection flow path 41 (ST4). As described above, the controller 50 controls the first and second connection flow path valves 42 and 43 to stop the antifreeze liquid in the connection flow path 41 when the system is stopped, and drives the pump 24 to drive the connection flow path 41. The antifreeze liquid in the coolant flow path 21 is caused to flow into the oxidant gas flow path 31. Thereafter, the controller 50 stops the pump 24 (ST5). Then, the process shown in FIG. 2 ends.

  In addition, the stop determination of the pump 24 in step ST5 is performed as follows. That is, the controller 50 stops the pump 24 when it is detected that the pressure drop has disappeared based on the detection value of the pressure sensor installed in the oxidant gas flow path 31, for example. Further, the controller 50 may stop the pump 24 when it is detected that the water level is not decreased based on the detection value of the water level sensor installed in the reservoir tank 23.

  FIG. 3 is a flowchart showing the operation of the fuel cell system 1 according to the first embodiment, and shows the operation when the fuel cell system 1 is started. First, it is assumed that the pump 24 and the compressor 32 of the fuel cell system 1 are in a stopped state. As shown in FIG. 3, when a system activation signal is input (ST11), the controller 50 opens the switching valve 33 (ST12). Thereafter, the controller 50 operates the compressor 32 (ST3). Thus, the controller 50 supplies the compressor 32 with air as the supply gas when the antifreeze liquid flows through the connection flow path 41 of the first and second connection flow path valves 42 and 43, thereby oxidizing. The antifreeze liquid sealed in the agent gas flow path 31 is returned to the coolant flow path 21.

  Then, the controller 50 controls the first connection channel valve 42 to block communication between the coolant channel 21 and the connection channel 41 (ST14). Further, the controller 50 controls the second connection flow path valve 43 to block communication between the oxidant gas flow path 31 and the connection flow path 41 (ST14). Thereafter, the controller 50 operates the pump 24 (ST15). And the process shown in FIG. 3 will be complete | finished.

  It should be noted that the flow passage judgment of the first and second connection flow passage valves 42 and 43 in step ST14 is performed as follows. That is, the controller 50 shuts off the flow path when it is detected that the pressure drop has disappeared based on the detection value of the pressure sensor installed in the coolant flow path 21, for example. Further, the controller 50 may block the flow path when it is detected that the water level does not increase based on the detection value of the water level sensor installed in the reservoir tank 23.

  Further, it is desirable that the oxidant gas flow path 31 has a layout that rises toward the inlet A so that the antifreeze liquid does not leak to the outside when the switching valve 33 is opened in step ST12. Further, the processes of step ST12 and step ST13 may be performed almost simultaneously to prevent the antifreeze liquid from leaking outside.

  Further, when the antifreeze liquid is caused to flow into the oxidant gas flow path 31 as in the above embodiment, the antifreeze liquid in the cooling liquid flow path 21 decreases or the antifreezing liquid in the cooling liquid flow path 21 disappears. There is no generated water generated by power generation in the flow path 21, and it can be said that the coolant flow path 21 does not freeze even if the antifreeze liquid in the coolant flow path 21 decreases or disappears.

  Next, a first modification of the fuel cell system 1 according to the first embodiment of the present invention will be described. FIG. 4 is a configuration diagram of a first modification of the fuel cell system 1 according to the first embodiment of the present invention. As shown in the figure, the fuel cell system 1 according to the first modification includes a fuel gas supply system 60, and the connection flow path 41 includes a coolant flow path 21 and a fuel gas flow path 61 of the fuel gas supply system 60. Is configured to connect.

  Specifically, the fuel gas supply system 60 includes a fuel gas passage (gas passage) 61, a hydrogen pump (gas supply means) 62, and a switching valve 63. The fuel gas channel 61 is a channel through which the fuel gas of the supply gas supplied to the fuel cell 10 flows. In addition, the fuel gas passage 61 is a passage through which the anode off gas discharged from the fuel cell 10 flows. The hydrogen pump 62 is provided in the fuel gas passage 61 and sends fuel gas into the fuel cell 10. The switching valve 63 is provided in the fuel gas channel 61 on the upstream side of the hydrogen pump 62, and opens or closes the fuel gas channel 61 by opening and closing. In the first modification, the second connection flow path valve 43 is provided at a connection portion between the fuel gas flow path 61 and the connection flow path 41.

  Next, the operation of the fuel cell system 1 according to the first modification will be described. FIG. 5 is a flowchart showing the operation of the fuel cell system 1 according to the first modification of the first embodiment, and shows the operation when the fuel cell system 1 is stopped.

  First, it is assumed that the pump 24 and the hydrogen pump 62 of the fuel cell system 1 are in an operating state. When a system stop signal is input as shown in FIG. 5 (ST21), the controller 50 stops the hydrogen pump 62 (ST22). Next, the controller 50 closes the switching valve 63 (ST23).

  Then, the controller 50 controls the first connection flow path valve 42 to connect the coolant flow path 21 and the connection flow path 41 (ST24). Further, the controller 50 controls the second connection flow path valve 43 to connect the fuel gas flow path 61 and the connection flow path 41 (ST24). Thereafter, the controller 50 stops the pump 24 (ST25). Then, the process shown in FIG. 5 ends.

  FIG. 6 is a flowchart showing the operation of the fuel cell system 1 according to the first modification of the first embodiment, and shows the operation when the fuel cell system 1 is activated. First, it is assumed that the pump 24 and the hydrogen pump 62 of the fuel cell system 1 are stopped. When a system activation signal is input as shown in FIG. 6 (ST31), the controller 50 opens the switching valve 63 (ST32). Thereafter, the controller 50 operates the hydrogen pump 62 (ST33).

  Then, the controller 50 controls the first connection channel valve 42 to block communication between the coolant channel 21 and the connection channel 41 (ST34). Furthermore, the controller 50 controls the second connection flow path valve 43 to block the communication between the fuel gas flow path 61 and the connection flow path 41 (ST34). Thereafter, the controller 50 operates the pump 24 (ST35). Then, the process shown in FIG. 6 ends.

  As described above, the antifreeze liquid may be caused to flow into the fuel gas passage 61 as in the first modification to prevent the fuel gas passage 61 from freezing. Further, the antifreeze may be allowed to flow into both the fuel gas channel 61 and the oxidant gas channel 31. Further, when the antifreeze liquid is allowed to flow into both, the processing at the time of system stop and the processing at the time of system startup may be performed first with respect to the oxidant gas flow channel 31 or may be performed first with respect to the fuel gas flow channel 61. . Moreover, you may make it perform both simultaneously.

  Next, a second modification of the fuel cell system 1 according to the first embodiment of the present invention will be described. In the fuel cell system 1 according to the second modification, the coolant channel 21 is provided at a position higher than the oxidant gas channel 31. For this reason, the antifreeze liquid flows from the coolant flow path 21 to the oxidant gas flow path 31 by its own weight through the connection flow path 41. Thereby, the antifreeze liquid can be caused to flow into the oxidant gas flow path 31 without pumping the antifreeze liquid by the pump 24.

  Further, in the fuel cell system 1 according to the second modification, the oxidant gas flow path 31 may be provided at a position higher than the coolant flow path 21. As a result, the antifreeze liquid flows from the oxidant gas flow path 31 to the coolant flow path 21 by its own weight through the connection flow path 41, and the antifreeze liquid can be returned to the coolant flow path 21 without being pumped by the compressor 32. it can.

  Here, in the first embodiment, the first modified example, and the second modified example, the controller 50 causes the antifreeze liquid in the coolant flow path 21 to flow into the oxidant gas flow path 31, and then the first and second coupled flows. It is desirable to control at least one of the path valves 42 and 43 to block communication with the connection channel 41 and to enclose the antifreeze liquid in the oxidant gas channel 31. Thereby, freezing can be reliably prevented without returning the antifreeze liquid to the coolant flow path 21. When the coolant flow path 21 is higher than the oxidant gas flow path 31, the antifreeze liquid is sealed in the oxidant gas flow path 31 with this configuration. That is, it is desirable that the antifreeze liquid does not return to the coolant flow path 21.

  Next, a third modification of the fuel cell system 1 according to the first embodiment of the present invention will be described. FIG. 7 is a flowchart showing the operation of the fuel cell system 1 according to the third modification of the first embodiment, and shows the operation when the fuel cell system 1 is stopped. Note that the processing in steps ST41 to ST45 shown in FIG. 7 is the same as the processing in steps ST1 to ST5 shown in FIG.

  After stopping the pump 24 in step ST45, the controller 50 opens the switching valve 33 (ST46). Thereafter, the controller 50 operates the compressor 32 (ST47). Then, the controller 50 controls the first connection channel valve 42 to block communication between the coolant channel 21 and the connection channel 41 (ST48). Further, the controller 50 controls the second connection channel valve 43 to block communication between the oxidant gas channel 31 and the connection channel 41 (ST48). Thereafter, the controller 50 stops the compressor 32 (ST49). Then, the process shown in FIG. 7 ends.

  As described above, as in the third modification, when the system is stopped, the antifreeze liquid may be caused to flow into the oxidant gas flow path 31 and then the antifreeze liquid in the oxidant gas flow path 31 may be returned to the coolant flow path 21. As a result, the generated water in the oxidant gas channel 31 is once washed away by the antifreeze liquid, and the possibility of freezing can be reduced even when the fuel cell system 1 is exposed to a low temperature environment. Further, it is not necessary to perform a startup flow (for example, the process shown in FIG. 3) when the system is started, and the startup time can be shortened.

  Thus, according to the fuel cell system 1 and the modification thereof according to the first embodiment, the connection channel 41 includes the connection channel 41 that connects the gas channels 31 and 61 and the coolant channel 21. Then, the antifreeze liquid in the coolant flow path 21 is caused to flow into the gas flow paths 31 and 61. As described above, since the antifreeze liquid is caused to flow into the gas flow paths 31 and 61, the gas flow path is not frozen by freezing of the generated water. In particular, since freezing is prevented by the antifreeze liquid, the fuel gas is not limited to low freezing point alcohol hydrocarbons such as methanol, and freezing can be prevented. Furthermore, in order to prevent freezing, it is only necessary to add the connection channel 41 and its peripheral parts 42 and 43 to the fuel cell system 1, and it is not necessary to add a methanol tank or a methanol supply device separately. Therefore, the system configuration is not greatly complicated. Therefore, the system configuration can be prevented from becoming very complicated, and the fuel gas to be used is not limited to the low freezing point alcohol hydrocarbons, and the system freezing by the generated water can be prevented.

  Further, when the system is stopped, the first and second connection flow path valves 42 and 43 are controlled so that the antifreeze liquid flows through the connection flow path 41, and the pump 24 is driven to drive the coolant flow through the connection flow path 41. The antifreeze liquid in the channel 21 is allowed to flow into the gas channels 31 and 61. As described above, the antifreeze liquid can be caused to flow into the gas flow paths 31 and 61 when the system is stopped only by controlling the first and second connection flow path valves 42 and 43 and driving the pump 24.

  In addition, since the antifreeze liquid is sealed in the gas flow paths 31 and 61 after the antifreeze liquid has flowed into the gas flow paths 31 and 61, the antifreeze liquid can be reliably prevented from freezing without returning to the coolant flow path 21. it can.

  Further, when the antifreeze liquid flows through the connection flow path 41 with respect to the first and second connection flow path valves 42 and 43, the gas flow paths 31 and 61 are supplied by supplying the supply gas with the compressor 32 and the hydrogen pump 62. The antifreeze liquid enclosed in the gas is returned to the gas flow paths 31 and 61. Therefore, the antifreeze liquid that has flowed into the gas flow paths 31 and 61 can be returned to the coolant flow path 21 and used again for cooling the fuel cell 10.

  The coolant channel 21 is provided at a position higher than the gas channels 31 and 61. For this reason, the antifreeze liquid flows from the coolant flow path 21 to the gas flow paths 31 and 61 by its own weight through the connection flow path 41, and the antifreeze liquid flows into the gas flow paths 31 and 61 without being pumped by the pump 24 or the like. Can be made.

  Further, the gas flow paths 31 and 61 are provided at a position higher than the coolant flow path 21. For this reason, the antifreeze liquid flows from the gas flow path 31 to the cooling liquid flow path 21 by its own weight through the connection flow path 41, and the antifreezing liquid can be returned to the cooling liquid flow path 21 without pumping the antifreezing liquid by the compressor 32 or the like. .

  Further, when the system is stopped, the first and second connection flow path valves 42 and 43 are controlled so that the antifreeze liquid flows through the connection flow path 41, and the pump 24 is driven to drive the coolant flow through the connection flow path 41. The antifreeze liquid in the channel 21 is caused to flow into the gas flow paths 31 and 61, and then the supply gas is supplied by the compressor 32 and the hydrogen pump 62, whereby the antifreeze liquid in the gas flow paths 31 and 61 is returned to the coolant flow path 21. As a result, the water produced in the gas flow paths 31 and 61 is once washed away by the antifreeze, and the possibility of freezing can be reduced even when the fuel cell system 1 is exposed to a low temperature environment. Also, it is not necessary to perform a startup flow when the system is started, and the startup time can be shortened.

  In addition, the pump 24 is used to allow the antifreeze liquid to flow into the gas flow paths 31, 61, and the compressor 32 and the hydrogen pump 62 are used to return the antifreeze liquid to the coolant flow path 21. be able to.

  Next, a second embodiment of the present invention will be described. The fuel cell system according to the second embodiment is the same as that of the first embodiment, but the configuration and processing contents are different. Hereinafter, differences from the first embodiment will be described.

  FIG. 8 is a configuration diagram of a fuel cell system according to the second embodiment of the present invention. As shown in the figure, the fuel cell system 2 according to the second embodiment newly includes a temperature sensor 71, a timer 72, and a determination unit 73.

  The temperature sensor 71 detects an outside air temperature around the fuel cell system 1. The timer 72 has a time measurement function, and measures the stop duration of the fuel cell system 1. The determination unit 73 determines whether or not the antifreeze liquid is allowed to flow into the oxidant gas flow path 31, and only when the determination unit 73 determines that the antifreeze liquid is allowed to flow into the oxidant gas flow path 31, the first and second connection flow path valves. The antifreeze liquid is caused to flow into the oxidant gas flow path 31 by controlling 42 and 43 and the like.

  FIG. 9 is a flowchart showing the operation of the fuel cell system 2 according to the second embodiment, and shows the operation when the fuel cell system 2 is stopped. First, it is assumed that the pump 24 and the compressor 32 of the fuel cell system 2 are in an operating state.

  When a system stop signal is input as shown in FIG. 9 (ST51), the controller 50 stops the compressor 32 (ST52). Next, the determination unit 73 reads information on the outside air temperature detected by the temperature sensor 71 (ST53). Thereafter, determination unit 73 determines whether or not the outside air temperature is 0 ° C. or less (ST54).

  Here, when it is determined that the outside air temperature is 0 ° C. or lower (ST54: YES), the process proceeds to step ST58, and the antifreeze liquid is caused to flow into the oxidant gas flow path 31. On the other hand, when it is determined that the outside air temperature is not 0 ° C. or lower (ST54: NO), the determination unit 73 reads the outside air temperature profile (ST55). Next, the determination unit 73 determines whether or not the outside air temperature may be 0 ° C. or less based on the outside air temperature profile (ST56).

  FIG. 10 is a diagram showing an outside air temperature profile. In FIG. 10, the vertical axis represents the outside air temperature (° C.), and the horizontal axis represents the scheduled stop time (hr). As shown in FIG. 10, the outside air temperature profile indicates the correlation between the outside air temperature and the scheduled stop time according to each region and season. The determination unit 73 measures the duration of the system stop by the timer 72 every time the fuel cell system 2 stops. And the determination part 73 accumulate | stores the information of a system stop continuation time. When the system stop signal is input, the determination unit 73 obtains a predicted stop time of the fuel cell system 2 based on information on the past system stop duration. Then, the determination unit 73 determines whether or not the outside air temperature becomes 0 ° C. or less within the scheduled stop time based on the outside air temperature corresponding to each region and season.

  Specifically, when the outside air temperature is 0 ° C. or lower as shown by the line L1 in FIG. 10, the controller 50 determines “YES” in step ST56, and the outside air temperature is 0 as shown by the line L2 in FIG. If it is not lower than ° C., “NO” is determined in step ST56. Further, the controller 50 determines “YES” in step ST56 because there is a possibility of freezing even when the outside air temperature temporarily becomes 0 ° C. or lower as indicated by a line L3 in FIG.

  When it is determined that there is no possibility that the outside air temperature becomes 0 ° C. or lower (ST56: NO), the controller 50 stops the pump 24 (ST57). Then, the process shown in FIG. 9 ends. As described above, when it can be determined that the outside air temperature is not 0 ° C. or less and is not likely to be 0 ° C. or less, there is no concern about freezing, and therefore the controller 50 causes the antifreeze liquid to flow into the oxidant gas flow path 31. The process is terminated without any processing.

  On the other hand, if it is determined that the outside air temperature may be 0 ° C. or less (ST56: YES), the process proceeds to step ST58, and the antifreeze liquid is caused to flow into the oxidant gas flow path 31. That is, the controller 50 closes the switching valve 33 (ST58) and controls the first connection flow path valve 42 to connect the coolant flow path 21 and the connection flow path 41 (ST59). Further, the controller 50 controls the second connection flow path valve 43 to connect the oxidant gas flow path 31 and the connection flow path 41 (ST59). As a result, the antifreeze liquid in the coolant channel 21 is caused to flow into the oxidant gas channel 31 via the connection channel 41. Thereafter, the controller 50 stops the pump 24 (ST57), and the process shown in FIG. 9 ends.

  In the second embodiment, the example in which the antifreeze liquid is allowed to flow into the oxidant gas flow path 31 has been described.

  Thus, according to the fuel cell system 2 according to the second embodiment, the system freezing due to the generated water can be prevented as in the first embodiment. Further, when the system is stopped, the antifreeze liquid can be caused to flow into the oxidant gas flow path 31, so that freezing can be surely prevented. Further, the antifreeze liquid that has flowed into the oxidant gas flow path 31 can be returned to the coolant flow path 21 and used again for cooling the fuel cell 10. Further, the antifreeze liquid can be caused to flow into the oxidant gas flow path 31 without pumping the antifreeze liquid by the pump 24 or the like, and the antifreeze liquid can be returned to the coolant flow path 21 without pumping the antifreeze liquid by the compressor 32 or the like. it can.

  Further, according to the second embodiment, whether or not the antifreeze liquid in the coolant flow path 21 is caused to flow into the gas flow paths 31 and 61 via the connection flow path 41 is determined based on the system stop duration time and the outside air around the system. Judgment is based on temperature. Here, if the system stop duration is short, for example, even if the fuel cell system 2 is in a low temperature environment, the possibility of freezing is small. Also, if the outside air temperature around the system is high, there may be no possibility of freezing in the first place. Therefore, it is determined whether or not the antifreeze liquid should flow into the gas flow paths 31 and 61 based on the system stop duration and the ambient temperature around the system, so that the antifreeze liquid flows into the gas flow paths 31 and 61 when necessary. Can be made.

  Next, a third embodiment of the present invention will be described. The fuel cell system according to the third embodiment is the same as that of the first embodiment, but the configuration and processing contents are different. Hereinafter, differences from the first embodiment will be described.

  FIG. 11 is a configuration diagram of a fuel cell system according to the third embodiment of the present invention. As shown in the figure, in the fuel cell system 3 according to the third embodiment, the antifreeze liquid moving system 40 is newly provided with a second connection channel (connection channel) 44, a water separation device 45, and a third connection channel. A valve (connection channel valve) 46 and a fourth connection channel valve (connection channel valve) 47 are provided.

  Similarly to the connection channel 41, the second connection channel 44 connects the coolant channel 21 and the oxidant gas channel 31. The water separation device 45 separates water from the antifreeze flowing through the second connection flow path 44 and has a water separation membrane. This water separation membrane separates water from the antifreeze liquid whose concentration has been reduced by containing water generated by the power generation in the fuel cell 10 so that the antifreeze liquid has a predetermined concentration. This water separation membrane utilizes, for example, the paver partition method (PV method). The PV method is a method in which a supply liquid is evaporated through a homogeneous membrane having no holes to obtain a concentrated liquid as permeated vapor. The water separator 45 has a mechanism for discharging the separated water to the outside. Note that the antifreeze liquid is brought to a predetermined concentration by the water separation membrane, and excess water is separated. Here, since the initial antifreeze liquid has a predetermined concentration, the water to be separated is generated water generated by power generation. Therefore, even if the separated water is discharged to the outside, the absolute amount of the antifreeze does not change and a problem due to the decrease in the antifreeze does not occur.

  Similarly to the first connection flow path valve 42, the third connection flow path valve 46 is provided at one end side of the second connection flow path 44, that is, at the connection portion between the coolant flow path 21 and the second connection flow path 44. ing. The third connection flow path valve 46 is constituted by a three-way valve, and is configured to communicate or block the coolant flow path 21 and the second connection flow path 44. The fourth connection flow path valve 47 is provided at the other end side of the second connection flow path 44, that is, at the connection portion between the oxidant gas flow path 31 and the second connection flow path 44. The fourth connection flow path valve 47 is configured by a three-way valve, and is configured to connect or block the oxidant gas flow path 31 and the second connection flow path 44. Moreover, these connection path | route valves 46 and 47 can adjust the flow volume of the antifreezing liquid which flows into the 2nd connection flow path 44 by adjusting an opening degree.

  FIG. 12 is a flowchart showing the operation of the fuel cell system 3 according to the third embodiment, and shows the operation when the fuel cell system 3 is activated. First, it is assumed that the pump 24 and the compressor 32 of the fuel cell system 3 are in a stopped state.

  When a system activation signal is input as shown in FIG. 12 (ST61), the controller 50 opens the switching valve 33 (ST62). The controller 50 controls the first connection channel valve 42 to block communication between the coolant channel 21 and the connection channel 41 (ST63). Furthermore, the controller 50 controls the second connection flow path valve 43 to block communication between the oxidant gas flow path 31 and the connection flow path 41 (ST63).

  Next, the controller 50 controls the third connection channel valve 46 to connect the coolant channel 21 and the second connection channel 44 (ST64). Furthermore, the controller 50 controls the fourth connection flow path valve 47 to connect the oxidant gas flow path 31 and the second connection flow path 44 (ST64). Thereafter, the controller 50 operates the compressor 32 (ST65). As a result, the antifreeze liquid is returned to the coolant flow path 21 through the second connection flow path 44. In addition, since the water separation device 45 is provided in the second connection channel 44, the concentration of the antifreeze liquid is adjusted by the water separation device 45 and then returned to the coolant channel 21.

  Next, the controller 50 controls the third connection channel valve 46 to block communication between the coolant channel 21 and the second connection channel 44 (ST66). Further, the controller 50 controls the fourth connection flow path valve 47 to block communication between the oxidant gas flow path 31 and the second connection flow path 44 (ST66). Thereafter, the controller 50 operates the pump 24 (ST67), and the process shown in FIG.

  Thus, according to the fuel cell system 3 according to the third embodiment, the system freezing due to the generated water can be prevented as in the first embodiment. Further, when the system is stopped, the antifreeze liquid can be caused to flow into the oxidant gas flow path 31, so that freezing can be surely prevented. Further, the antifreeze liquid that has flowed into the oxidant gas flow path 31 can be returned to the coolant flow path 21 and used again for cooling the fuel cell 10. Further, the antifreeze liquid can be caused to flow into the oxidant gas flow path 31 without pumping the antifreeze liquid by the pump 24 or the like, and the antifreeze liquid can be returned to the coolant flow path 21 without pumping the antifreeze liquid by the compressor 32 or the like. it can.

  In addition, according to the third embodiment, the water separation membrane is provided that separates water from the antifreeze liquid whose concentration has been reduced by including water generated by the power generation in the fuel cell 10 so that the antifreeze liquid has a predetermined concentration. For this reason, even when the antifreeze liquid and the produced water are mixed and the concentration of the antifreeze liquid is lowered, it is possible to separate the water by the water separation membrane and return the antifreeze liquid concentration to a predetermined concentration. Therefore, the non-freezing performance at a predetermined concentration can be maintained.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and modifications may be made without departing from the spirit of the present invention. May be combined.

  For example, in the above-described embodiment, the configuration including the hydrogen pump 62 has been described. However, the hydrogen pump 62 is not provided, a high-pressure hydrogen tank and a control valve are provided, and the opening degree of the control valve is adjusted so that the hydrogen gas is fueled. The structure supplied to the battery 10 may be sufficient.

1 is a configuration diagram of a fuel cell system according to a first embodiment of the present invention. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 1st Embodiment, and has shown operation | movement at the time of a stop of a fuel cell system. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 1st Embodiment, and has shown operation | movement at the time of starting of a fuel cell system. It is a block diagram of the 1st modification of the fuel cell system which concerns on 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the fuel cell system which concerns on the 1st modification of 1st Embodiment, and has shown operation | movement at the time of a stop of a fuel cell system. It is a flowchart which shows operation | movement of the fuel cell system which concerns on the 1st modification of 1st Embodiment, and has shown operation | movement at the time of starting of a fuel cell system. It is a flowchart which shows operation | movement of the fuel cell system which concerns on the 3rd modification of 1st Embodiment, and has shown operation | movement at the time of a stop of a fuel cell system. It is a block diagram of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 2nd Embodiment, and has shown operation | movement at the time of a stop of a fuel cell system. It is a figure which shows an external temperature profile. It is a block diagram of the fuel cell system which concerns on 3rd Embodiment of this invention. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 3rd Embodiment, and has shown operation | movement at the time of starting of a fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-3 ... Fuel cell system 10 ... Fuel cell 20 ... Coolant circulation system 21 ... Coolant flow path 22 ... Radiator 23 ... Reservoir tank 24 ... Pump (coolant circulation means)
30 ... Oxidant gas supply system 31 ... Oxidant gas channel (gas channel)
32. Compressor (gas supply means)
33 ... Switching valve 40 ... Antifreeze liquid moving system 41 ... Connection flow path (connection flow path)
42 ... 1st connection flow path valve (connection flow path valve)
43. Second connection flow path valve (connection flow path valve)
44 ... 2nd connection channel (connection channel)
45 ... Water separation device 46 ... Third connection flow path valve (connection flow path valve)
47. Fourth connection flow path valve (connection flow path valve)
50. Controller (control means)
60 ... Fuel gas supply system 61 ... Fuel gas flow path (gas flow path)
62 ... Hydrogen pump (gas supply means)
63 ... Switching valve 71 ... Temperature sensor 72 ... Timer 73 ... Determination part

Claims (8)

A fuel cell for generating electricity by reacting the supplied gas, and
A coolant flow path that serves as a flow path for circulating the antifreeze liquid;
A gas flow path through which a supply gas supplied to the fuel cell and a gas discharged from the fuel cell flow;
A connecting flow path connecting the gas flow path and the coolant flow path;
Control means for causing the antifreeze liquid in the coolant flow path to flow into the gas flow path via the connection flow path;
A fuel cell system comprising: A connection flow path valve capable of adjusting the flow rate of the antifreeze flowing through the connection flow path;
A coolant circulation means that serves as a drive source for circulating the antifreeze liquid in the coolant flow path,
The control means controls the connection flow path valve when the system is stopped so that the antifreeze liquid flows through the connection flow path, and drives the cooling liquid circulation means to drive the cooling liquid flow through the connection flow path. The fuel cell system according to claim 1, wherein an antifreeze liquid in a passage is caused to flow into the gas passage. The fuel cell system according to claim 2, wherein the control unit fills the antifreeze liquid in the gas flow path after flowing the antifreeze liquid into the gas flow path. Gas supply means for supplying a supply gas to the fuel cell;
The control means causes the gas supply means to supply a supply gas when the antifreeze liquid flows through the connection flow path with respect to the connection flow path valve, thereby removing the antifreeze liquid enclosed in the gas flow path. The fuel cell system according to claim 3, wherein the fuel cell system is returned to the coolant flow path. The control means determines whether or not to allow the antifreeze liquid in the coolant flow path to flow into the gas flow path through the connection flow path, based on a system stop duration and an outside air temperature around the system. The fuel cell system according to any one of claims 1 to 4, wherein the fuel cell system is provided. The fuel cell system according to any one of claims 1 to 5, wherein the coolant channel is provided at a position higher than the gas channel. The fuel cell system according to any one of claims 1 to 5, wherein the gas flow path is provided at a position higher than the coolant flow path. The water separation membrane which isolate | separates water from the antifreeze liquid which the density | concentration fell by containing the water produced | generated by the electric power generation in the said fuel cell, and makes an antifreeze liquid a predetermined density | concentration is further provided. 8. The fuel cell system according to any one of 7 above.

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