JP2007134241A - Fuel cell cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain both long-time heat insulation and shortening of temperature-raising time of cooling water, in a fuel cell cooling system cooling a fuel cell by circulation of cooling water. <P>SOLUTION: The fuel cell cooling system is provided with a radiator channel 4 circulating cooling water to a radiator 3 carrying out radiation of the cooling water, a tank channel 6 circulating the cooling water to a tank 5 for storing it, and a bypass channel 7 for circulating the cooling water by bypassing the radiator 3 and the tank 5. Channels are to be changed over by an ECU 100 so that, if water temperature of the tank 5 is below freezing point at start-up of the fuel cell stack 2, the cooling water is made to flow through the bypass channel 7, and, if it is above freezing point, the cooling water is made to flow through the tank channel 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell cooling system that circulates cooling water to cool a fuel cell, and more particularly, to a fuel cell cooling system that achieves both long-term insulation of cooling water and shortening of temperature rising time.

  Fuel cell technology is attracting attention as a power source that enables clean exhaust and high energy efficiency against environmental problems in recent years, particularly air pollution caused by automobile exhaust gas and global warming caused by carbon dioxide.

  A fuel cell is an energy conversion system that supplies hydrogen gas as a fuel gas and air as an oxidant gas to a fuel cell stack and causes an electrochemical reaction to convert chemical energy into electric energy.

  Among such fuel cell systems, a solid polymer electrolyte fuel cell having a particularly high power density is generally controlled so that the stack temperature is 85 ° C. or lower. Therefore, a heat exchanger such as a radiator and the like It has a cooling system including a pump that circulates cooling water.

  As a conventional example of a fuel cell system provided with such a cooling system, for example, Japanese Unexamined Patent Application Publication No. 2004-158279 (Patent Document 1) is disclosed.

This conventional example includes a radiator that cools the cooling water by heat radiation, and a bypass passage that bypasses the radiator and allows the cooling water to flow. The fuel cell stack and the bypass passage are housed in an FC box so that the cooling water is supplied during warm-up. By flowing to the bypass passage, the heat of the cooling water was prevented from radiating to the outside.
JP 2004-158279 A

  However, in the above-described conventional fuel cell system, the bypass passage and the fuel cell stack are accommodated in the insulated FC box. Therefore, in order to raise the temperature by the heat generation of the fuel cell stack, depending on the heat capacity of the FC box The temperature rise time is affected.

  At this time, if the heat capacity of the FC box is small, the temperature rise time will be faster, but it will be easily affected by the outside air. Will fall. Conversely, if the heat capacity of the FC box is increased, such as by making the pipe thicker, it will be less susceptible to the influence of outside air, so it may take a long time to rise, although it may be kept at a higher temperature than the outside air at system startup. End up.

  As described above, in the above-described conventional fuel cell system, it has been difficult to achieve both the contradiction of increasing the temperature of the cooling water and keeping the inside of the FC box warm for a long time.

  In order to solve the above-described problems, a fuel cell cooling system according to the present invention is a fuel cell cooling system that circulates cooling water to cool the fuel cell, and circulates the cooling water to a radiator that radiates the cooling water. A radiator path, a tank path that circulates the cooling water to a tank that stores the cooling water, and a bypass path that bypasses the radiator and the tank and circulates the cooling water. When the water temperature of the stored cooling water is below the freezing point, the path is switched so that the cooling water flows to the bypass path, and when the cooling water temperature stored in the tank is higher than the freezing point, the cooling water flows to the tank path. When the water temperature at the inlet of the fuel cell becomes 0 ° C. or higher, the path is gradually switched to the bypass path. It is characterized in.

  In the fuel cell cooling system according to the present invention, since the tank for storing the cooling water is provided, the heat capacity can be increased, and a decrease in the cooling water temperature can be suppressed when the system is stopped. In particular, it is possible to suppress a decrease in the temperature of the cooling water stored in the tank.

  In addition, when the coolant temperature stored in the tank is below freezing point, the coolant is circulated using the bypass route, so most of the coolant is stored in the tank, and less coolant water in the bypass route is used. It is only necessary to raise the temperature, and the heat capacity can be reduced to shorten the temperature raising time.

  Therefore, it is possible to achieve both shortening of the temperature raising time and extension of the heat retention time, which were difficult in the past.

  Embodiments of a fuel cell system to which a fuel cell cooling system according to the present invention is applied will be described below with reference to the drawings.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the fuel cell system according to this embodiment.

  As shown in FIG. 1, the fuel cell system 1 of this embodiment includes a fuel cell stack 2 that is supplied with fuel gas and an oxidant gas and generates electric power through an electrochemical reaction, and a radiator 3 that cools cooling water by heat dissipation. A radiator path 4 for circulating cooling water to the radiator 3, a tank 5 for storing cooling water, a tank path 6 for circulating cooling water to the tank 5, a bypass path 7 for bypassing the radiator 3 and the tank 5, and a radiator A first three-way valve 8 for switching between the path 4 and the bypass path 7, a second three-way valve 9 for switching between the tank path 6 and the bypass path 7, a cooling water pump 10 for circulating cooling water, the fuel cell stack 2 and the tank 5 and the heat insulating box 11 that stores the bypass path 7, and the inlet water temperature sensor 1 that detects the coolant temperature at the inlet of the fuel cell stack 2. An outlet water temperature sensor 13 for detecting the coolant temperature at the outlet of the fuel cell stack 2, a tank water temperature sensor 14 for detecting the coolant temperature stored in the tank 5, an ECU (Electric Control Unit) 100, It has.

  In the fuel cell system 1 described above, in the fuel cell stack 2, hydrogen gas, which is fuel gas, is supplied to the anode, and air, which is oxidant gas, is supplied to the cathode, and power generation is performed by the following electrochemical reaction. .

Anode (anode): H2 → 2H ++ 2e- (1)
Cathode (Cathode): 2H ++ 2e-+ (1/2) O2 → H2O (2)
In the hydrogen supply system that supplies hydrogen to the fuel cell stack 2, hydrogen gas is supplied from the hydrogen tank to the anode of the fuel cell stack 2 through a pressure reducing valve, a hydrogen supply valve, and the like.

  On the other hand, in an air supply system that supplies air that is an oxidant gas, air sucked from the outside is pressurized by the compressor and supplied to the cathode of the fuel cell stack 2.

  In addition, since the tank 5 has a capacity equal to or larger than the amount of cooling water retained in the fuel cell stack 2, the high-temperature cooling water stored in the tank 5 at the time of start-up is cooled with the cooled fuel. The battery stack 2 can be filled, whereby the temperature rise at the start of the fuel cell stack 2 can be accelerated and the start-up time can be further shortened.

  Furthermore, since the heat insulation box 11 is insulated from the outside and houses the fuel cell stack 2, the tank 5, and the bypass path 7, the heat insulation box 11 uses a large amount of cooling water stored in the tank 5. 11 can be kept warm for a long time, whereby the startup time of the fuel cell stack 2 can be further shortened.

  In addition to the operation of the fuel cell stack 2, the ECU (control means) 100 switches the three-way valves 8, 9 based on the temperatures detected by the inlet water temperature sensor 12, the outlet water temperature sensor 13, and the tank water temperature sensor 14, and The operation of the cooling water pump 10 is controlled. The ECU 100 is constituted by a microcomputer including a CPU, a ROM, a RAM, and the like. Of the functions of the ECU 100, the processing related to the switching of the coolant path may be performed by another ECU.

  Next, the cooling water path switching process when the fuel cell system 1 of this embodiment is started will be described with reference to the flowchart of FIG.

  As shown in FIG. 2, when the fuel cell stack 2 is activated, the ECU 100 starts the operation of the cooling water pump 10 (S201). At this time, even if the outside air temperature is below the freezing point, the circulation path of the cooling water surrounded by the heat insulating box 11 is not easily affected by the outside air temperature, and the cooling water is stored in the tank 5. As a result, the heat capacity is increased and the structure is less susceptible to outside air temperature.

  Then, the ECU 100 detects the water temperature in the tank 5 by the tank water temperature sensor 14 and determines whether or not the water temperature is maintained at a temperature higher than 0 ° C. (S202). When the water temperature of the tank 5 is higher than 0 ° C., the first and second three-way valves 8 and 9 are switched to switch the path so that the cooling water circulates between the tank path 6 and the tank 5 (S203).

  Thereafter, power generation of the fuel cell stack 2 is started (S204), the temperature of the cooling water is raised (S205), and the temperature of the cooling water at the outlet of the fuel cell stack 2 is then detected by the outlet temperature sensor 13 to normally It is determined whether or not the operating temperature required during operation has risen (S206).

  When the water temperature at the outlet of the fuel cell stack 2 becomes higher than the operating temperature, the first and second three-way valves 8 and 9 are switched to switch the path so that the cooling water circulates in the bypass path 7 (S207). Cold cooling water remaining in the bypass path 7 is mixed.

  Similarly, when it is determined in step S202 that the water temperature in the tank 5 is below the freezing point of the outside air temperature when the system is left stopped for a long time, the first and second three-way valves 8, 9 is switched to the bypass path 7 side, and the path is switched so that the cooling water flows to the bypass path 7 (S207).

  When the first and second three-way valves 8 and 9 are thus switched to the bypass path 7 side, normal operation of the fuel cell stack 2 is started (S208), and the cooling water at the time of startup of the fuel cell system 1 of this embodiment is started. The route switching process is terminated.

  Here, the coolant temperature change in the case where the above-described cooling water path switching process is performed will be described.

  First, the temperature change of the cooling water in the conventional fuel cell system in which the tank 5 is not installed will be described with reference to FIG. As shown in FIG. 3, when the fuel cell stack stops operation, the water temperature in the bypass section that bypasses the radiator and the water temperature in the fuel cell stack decrease with the same change from the operating temperature of the fuel cell stack to the outside air temperature. Similarly, when the fuel cell stack is started, the temperature rises similarly from the outside temperature to the operating temperature.

  On the other hand, in the fuel cell system 1 of the present embodiment, when the fuel cell stack 2 stops operating as shown in FIG. 4, a large amount of cooling water is stored in the tank 5, so that the heat capacity increases. The water temperature in the tank 5 is difficult to decrease. Next to this, the water temperature in the fuel cell stack 2 becomes difficult to decrease, and the water temperature in the bypass path 7 is lowered to the outside temperature most quickly.

  Thereafter, when the fuel cell stack 2 is started up, if the water temperature in the tank 5 is 0 ° C. or higher, the cooling water circulates through the tank path 6, so the water temperature in the tank 5 is the water temperature in the fuel cell stack 2. The water temperature of the fuel cell stack 2 and the water temperature of the tank 5 rise with the same change. During this time, the cooling water does not flow through the bypass path 7, so the water temperature of the bypass path 7 remains at the outside air temperature.

When the water temperature of the fuel cell stack 2 and the water temperature of the tank 5 rise to the operating temperature of the fuel cell stack 2, the first and second three-way valves 8 and 9 are switched to flow the cooling water to the bypass path 7, so that the bypass path The water temperature of 7 begins to rise.

  On the other hand, when the water temperature in the tank 5 has dropped to 0 ° C. or lower while the fuel cell stack 2 is stopped, the first and second three-way valves 8, when the fuel cell stack 2 is started, as shown in FIG. 9 is switched so that the cooling water flows to the bypass path 7.

  As a result, the cooling water stored in the tank 5 does not circulate after the fuel cell stack 2 is started, so the water temperature in the tank 5 does not rise at the same temperature as the outside air temperature, and the water temperature in the bypass path 7 and the fuel cell stack 2 The water temperature inside rises. At this time, since only a small amount of cooling water in the bypass path 7 needs to be heated, the temperature of the cooling water can be rapidly raised to the operating temperature of the fuel cell stack 2.

  Thus, in the fuel cell system 1 of the present embodiment, since the tank 5 for storing the cooling water is provided, the heat capacity can be increased, and the cooling water temperature drop can be suppressed when the system is stopped. . In particular, it is possible to suppress a decrease in the temperature of the cooling water stored in the tank 5.

  Further, when the coolant temperature stored in the tank 5 is below the freezing point, the coolant is circulated using the bypass path 7, so that most of the coolant is stored in the tank 5 and is in the bypass path 7. It is only necessary to heat a small amount of cooling water, and the heat capacity can be reduced to shorten the temperature raising time.

  Therefore, it has become possible to achieve both shortening of the temperature raising time and extension of the heat retention time, which were difficult in the past.

  Further, in the fuel cell system 1 of the present embodiment, the capacity of the tank 5 is equal to or greater than the amount of cooling water retained in the fuel cell stack 2, so that the heat-retaining cooling water stored in the tank 5 at the time of startup is stored. Can be filled in the cooled fuel cell stack 2, thereby accelerating the temperature rise at the start of the fuel cell stack 2 and further shortening the startup time.

  Furthermore, in the fuel cell system 1 of the present embodiment, the fuel cell stack 2, the tank 5, and the bypass path 7 are installed in the heat insulation box 11 insulated from the outside, so that a large amount of cooling water stored in the tank 5 is stored. The inside of the heat insulation box 11 can be kept warm for a long time using this, whereby the startup time of the fuel cell stack 2 can be further shortened.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flow chart showing the cooling water path switching process when the fuel cell system of this embodiment is started. However, since the configuration of the fuel cell system of the present embodiment is the same as that of the first embodiment, detailed description thereof is omitted.

  As shown in FIG. 6, the processing from step S301 to S305 is the same as the processing from step S201 to S205 in FIG.

  When the coolant temperature starts to rise due to the power generation of the fuel cell stack 2 in step S305, the ECU 100 detects the coolant temperature at the inlet of the fuel cell stack 2 by the inlet temperature sensor 12 and determines whether or not the coolant temperature has risen to 0 ° C. or higher. Is determined (S306).

  When the water temperature at the inlet of the fuel cell stack 2 rises to 0 ° C. or higher, the second three-way valve 9 is slightly opened to the bypass path 7 side so that a small amount of cooling water flows to the bypass path 7 (S307). At this time, the opening degree of the second three-way valve 9 is adjusted so that the coolant temperature does not fall below 0 ° C.

  If the second three-way valve 9 is slightly opened to the bypass path 7 in this way, it is determined whether or not the opening degree of the second three-way valve 9 is fully opened to the bypass path 7 side (S308). In this case, the process returns to step S306 and the above-described processing is repeated, and the second three-way valve 9 is gradually opened until the opening degree of the second three-way valve 9 is fully opened to the bypass path 7 side.

  When the opening degree of the second three-way valve 9 is fully opened to the bypass path 7 side, the normal operation of the fuel cell stack 2 is started (S309), and the cooling water at the time of starting the fuel cell system of this embodiment is started. The route switching process is terminated.

  If it is determined in step S302 that the system has been stopped for a long period of time or the like, and the water temperature in the tank 5 is below the freezing point equivalent to the outside air temperature, the first and second three-way valves 8 are used. , 9 to the bypass path 7 side so that the cooling water flows to the bypass path 7 (S310), normal operation of the fuel cell stack 2 is started (S309), and the fuel cell system of this embodiment is started. At this time, the cooling water path switching process is terminated.

  Here, the coolant temperature change in the case where the above-described cooling water path switching process is performed will be described.

  In the fuel cell system of this embodiment, when the fuel cell stack 2 stops operating as shown in FIG. 7, the water temperature in the bypass path 7 becomes the lowest, then the water temperature in the fuel cell stack 2 becomes lower, and the tank 5 Water temperature is highest.

  When the fuel cell stack 2 is started when the water temperature in the tank 5 is 0 ° C. or higher, the first and second three-way valves 8 and 9 are first switched to the tank path 6 side, so that the cooling water circulates in the tank path 6. Then, the water temperature in the tank 5 starts to rise after being lowered to the water temperature in the fuel cell stack 2 once.

  Thereafter, when the water temperature at the inlet of the fuel cell stack 2 rises to 0 ° C. or higher, the second three-way valve 9 starts to gradually open toward the bypass path 7, so that the water temperature of the bypass path 7 rises.

  When the second three-way valve 9 is fully opened to the bypass path 7 side, the water temperature of the fuel cell stack 2 and the water temperature of the bypass path 7 are similarly raised to the operating temperature of the fuel cell stack 2.

  Thus, in the fuel cell system of this embodiment, when the temperature of the cooling water stored in the tank 5 is higher than below freezing point, the path is first switched so that the cooling water flows to the tank path 6. Immediately after startup, the water temperature can be raised using the cooling water in the tank 5 having a relatively high temperature.

  Thereafter, when the water temperature at the inlet of the fuel cell stack 2 becomes 0 ° C. or higher, the path is gradually switched to the bypass path 7, so the flow rate of the circulating cooling water is reduced to reduce the heat capacity, thereby rapidly cooling the cooling water. The water temperature can be raised.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. FIG. 8 is a flowchart showing a coolant switching process when the fuel cell system according to the present embodiment is started. However, since the configuration of the fuel cell system of the present embodiment is the same as that of the first embodiment, detailed description thereof is omitted.

  As shown in FIG. 8, when the fuel cell stack 2 is activated, the ECU 100 starts the operation of the cooling water pump 10 (S401), and the water temperature at the outlet of the fuel cell stack 2 detected by the outlet water temperature sensor 13 is the fuel. It is determined whether or not the temperature is lower than the operating temperature required during operation of the battery stack 2 (S402).

  Here, when the water temperature at the outlet of the fuel cell stack 2 is lower than the operating temperature, the same processes as those in steps S302 to S310 of FIG. 6 described in the second embodiment are performed in steps S403 to S411.

  On the other hand, when it is determined in step S402 that the water temperature at the outlet of the fuel cell stack 2 is equal to or higher than the operating temperature, the path is switched so that the first three-way valve 8 is opened to the radiator path 4 and the cooling water flows to the radiator 3. Then (S412), the normal operation of the fuel cell stack 2 is started (S410), and the cooling water path switching process at the start of the fuel cell system of this embodiment is completed.

  Thus, in the fuel cell system of this embodiment, when the temperature of the water at the outlet of the fuel cell stack 2 is higher than the operating temperature when the fuel cell stack 2 is started, the path is switched so that the cooling water flows to the radiator path 4. The fuel cell stack 2 can be prevented from being heated regardless of the state of the coolant temperature and the outside air temperature when the fuel cell stack 2 is started. For example, even when the outside air temperature is below freezing, the fuel cell stack 2 can be cooled in the case of so-called hot restart, and heating of the fuel cell stack 2 can be prevented.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a flowchart showing a coolant water path switching process when the fuel cell system according to this embodiment is stopped. However, since the configuration of the fuel cell system of the present embodiment is the same as that of the first embodiment, detailed description thereof is omitted.

  As shown in FIG. 9, first, when a command for notifying the operation stop of the fuel cell stack 2 is input (S501), the ECU 100 switches the first and second three-way valves 8, 9 to the tank path 6 side (S502). Cooling water rising to the operating temperature is circulated into the tank 5.

  Then, it is determined whether or not the water temperature in the tank 5 detected by the tank water temperature sensor 14 and the outlet water temperature of the fuel cell stack 2 detected by the outlet water temperature sensor 13 are substantially equal (S503). If the fuel cell stack 2 has stopped, the power generation of the fuel cell stack 2 is stopped (S504), the cooling water pump 10 is stopped (S505), and the cooling water path switching process when the fuel cell system of this embodiment is stopped is terminated.

  Thus, in the fuel cell system of the present embodiment, the path is switched so that the cooling water flows to the tank path 6 when the fuel cell stack 2 is stopped, and the water temperature in the tank 5 and the water temperature at the outlet of the fuel cell stack 2 are equal. Since the fuel cell stack 2 is stopped after the cooling water is circulated until the cooling water rises, the cooling water whose temperature has risen due to the heat generated by the fuel cell stack 2 can be stored in the tank 5 immediately before the stop, and until the next start after the system stops Can be kept warm for as long as possible.

  Further, since the fuel cell stack 2, the bypass path 7 and the tank 5 are accommodated in the same heat insulating box 11, the water temperature of the tank 5 gradually becomes the same temperature as the fuel cell stack 2 during operation. However, when the operation is stopped in a short time, the tank 5 may not rise to the operating temperature. At this time, the cooling water whose temperature has risen due to the heat generated by the fuel cell stack 2 is stored in the tank 5 immediately before the stop, so that the heat retention time can be maximized between the system stop and the next start. It is possible to gradually put the cooling water into the tank 5 during the operation of the system, but it is possible to keep the temperature more efficiently if the cooling water is put into the tank 5 just before the system is stopped.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a block diagram showing the configuration of the fuel cell system of this embodiment.

  As shown in FIG. 10, the fuel cell system 51 of the present embodiment is different from that of the first embodiment in that a bypass path 52 is installed between the fuel cell stack 2 and the tank 5. Detailed explanation is omitted.

  As described above, in the fuel cell system 51 of the present embodiment, the bypass path 52 is disposed between the tank 5 and the fuel cell stack 2, so that the bypass path 52 can be surrounded by parts having a large heat capacity. Can be kept warm for a longer time.

  Next, Embodiment 6 of the present invention will be described with reference to FIG. FIG. 11 is a block diagram showing the configuration of the fuel cell system of the present embodiment.

  As shown in FIG. 11, the fuel cell system 61 of the present embodiment is different from the first embodiment in that a heater 62 is installed in the tank 5, and the other configuration is the same as that of the first embodiment. To do.

  Here, when the fuel cell stack 2 is activated, the heater 62 is supplied with electric power generated by the fuel cell stack 2 under the control of the ECU 100 and heats the cooling water stored in the tank 5.

  Thus, in the fuel cell system 61 of the present embodiment, the heater 62 is installed in the tank 5 to heat the cooling water, so that the startup time of the fuel cell stack 2 can be further shortened. Further, since the heater 62 is installed in the tank 5 having a large volume, local heating by the heater 62 can be suppressed.

  Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG. 12 is a block diagram showing the configuration of the fuel cell system of the present embodiment.

  As shown in FIG. 12, the fuel cell system 71 of this embodiment includes an ion sensor 72 that detects the conductivity of the cooling water, and an ion filter 73 that is installed in the tank 5 to remove the ions of the cooling water. Further, what is provided is different from that of the first embodiment, and other configurations are the same as those of the first embodiment, and thus detailed description thereof is omitted.

  In general, in a fuel cell cooling system, it is necessary to keep the conductivity of cooling water low so that electricity does not flow from the fuel cell stack through the cooling water. Therefore, in the fuel cell system 71 of the present embodiment, the ECU 100 detects the conductivity of the cooling water using the ion sensor 72, and when the detected conductivity exceeds a predetermined value, the first and second three-way valves 8, 9 are turned on. The cooling water is switched to flow to the tank path 6 and ions in the cooling water are removed by the ion filter 73 installed in the tank 5.

  As described above, the fuel cell system 71 of the present embodiment further includes the ion sensor 72 that detects the conductivity of the cooling water, and the ion filter 73 installed in the tank 5 in order to remove the ions of the cooling water, When the conductivity detected by the ion sensor 72 exceeds a predetermined value, the path is switched so that the cooling water flows to the tank path 6, so that the ions in the cooling water can be removed by the ion filter 73 and the conductivity of the cooling water. Can be kept low.

  Moreover, since the ion filter 73 is installed in the tank 5, it is not necessary to install another bypass circuit for installing the ion filter, and space saving can be realized. Further, since the tank 5 is insulated, the coolant temperature can be kept high, so that the ion exchange performance of the ion filter 73 can be made more efficient. Further, from the characteristics of conductivity, the conductivity value (the state of electricity flow) is lower at the low temperature even at the same ion component than at the high temperature. Therefore, by utilizing this characteristic, the cooling water is allowed to flow only through the bypass path 7 at the time of startup, whereby the cold cooling water circulates and the conductivity of the cooling water can be lowered.

  Although the fuel cell system of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. Can do.

It is a block diagram which shows the structure of the fuel cell system which concerns on Example 1 of this invention. It is a flowchart which shows the path | route switching process of the cooling water at the time of starting of the fuel cell system which concerns on Example 1 of this invention. It is a figure for demonstrating the water temperature change of the cooling water at the time of starting of the conventional fuel cell system. It is a figure for demonstrating the water temperature change of the cooling water at the time of starting of the fuel cell system which concerns on Example 1. FIG. It is a figure for demonstrating the water temperature change of the cooling water at the time of starting of the fuel cell system which concerns on Example 1. FIG. It is a flowchart which shows the path | route switching process of the cooling water at the time of starting of the fuel cell system which concerns on Example 2 of this invention. It is a figure for demonstrating the water temperature change of the cooling water at the time of starting of the fuel cell system which concerns on Example 2. FIG. It is a flowchart which shows the path | route switching process of the cooling water at the time of starting of the fuel cell system which concerns on Example 3 of this invention. It is a flowchart which shows the path | route switching process of the cooling water at the time of the stop of the fuel cell system which concerns on Example 4 of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on Example 5 of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on Example 6 of this invention. It is a block diagram which shows the structure of the fuel cell system which concerns on Example 7 of this invention.

Explanation of symbols

1, 51, 61, 71 Fuel cell system 2 Fuel cell stack 3 Radiator 4 Radiator path 5 Tank 6 Tank path 7, 52 Bypass path 8 First three-way valve 9 Second three-way valve 10 Cooling water pump 11 Heat insulation box 12 Inlet water temperature sensor 13 outlet water temperature sensor 14 tank water temperature sensor 62 heater 72 ion sensor 73 ion filter 100 ECU (control means)

Claims (8)

A fuel cell cooling system for circulating a cooling water to cool a fuel cell,
A radiator path that circulates cooling water to a radiator that radiates cooling water, a tank path that circulates cooling water to a tank that stores cooling water, and a bypass path that circulates cooling water by bypassing the radiator and the tank And a control means for controlling switching of each route,
The control means switches the path so that the cooling water flows to the bypass path when the temperature of the cooling water stored in the tank when the fuel cell is started is below the freezing point,
When the water temperature of the cooling water stored in the tank is higher than below freezing point, the path is switched so that the cooling water flows to the tank path, and when the water temperature at the inlet of the fuel cell becomes 0 ° C. or higher, the bypass is gradually A fuel cell cooling system characterized by switching a route to a route.   2. The control unit according to claim 1, wherein when the fuel cell is started up, when the water temperature at the outlet of the fuel cell is higher than the operating temperature of the fuel cell, the control unit switches the path so that cooling water flows to the radiator path. The fuel cell cooling system as described.   When the fuel cell is stopped, the control means switches the path so that the cooling water flows to the tank path, and circulates the cooling water until the water temperature in the tank and the water temperature at the outlet of the fuel cell become equal. The fuel cell cooling system according to claim 1, wherein the fuel cell is stopped after a while.   The fuel cell cooling system according to any one of claims 1 to 3, wherein the bypass path is disposed between the tank and the fuel cell.   5. The fuel cell cooling system according to claim 1, wherein a capacity of the tank is at least equal to a cooling water holding amount of the fuel cell. 6.   The fuel cell cooling system according to any one of claims 1 to 5, further comprising a heater that heats the tank, and the coolant is heated by the heater. An ion sensor that detects the conductivity of the cooling water, and an ion filter installed in the tank to remove cooling water ions;
The said control means switches a path | route so that cooling water may flow into the said tank path | route, if the electrical conductivity detected by the said ion sensor becomes more than predetermined value. A fuel cell cooling system according to claim 1. The fuel cell cooling system according to any one of claims 1 to 7, wherein the fuel cell, the tank, and the bypass path are installed in a heat insulation box insulated from the outside. .

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