JP7522082B2 - Fuel Cell Cooling System - Google Patents

Description

The technology disclosed in this specification relates to a fuel cell cooling system.

The fuel cell cooling system disclosed in Patent Document 1 cools a fuel cell mounted on a vehicle. This fuel cell cooling system has a refrigerant flow path through which a refrigerant flows. The refrigerant flow path is provided with a cooler that cools the refrigerant in the refrigerant flow path, and a fuel cell that is cooled by heat exchange with the refrigerant in the refrigerant flow path. The refrigerant cooled by the cooler is supplied to the fuel cell, thereby cooling the fuel cell.

JP 2008-126911 A

In some cases, a flow path for cooling other heat generating elements is provided in parallel with the flow path in which the fuel cell is provided. In the following, the flow path in which the fuel cell is provided is referred to as the fuel cell flow path, and the flow path in which the heat generating element is provided is referred to as the heat generating element flow path. Also, the flow path in which the cooler is provided is referred to as the cooler flow path. The refrigerant that has passed through the cooler flow path branches into the fuel cell flow path and the heat generating element flow path. The refrigerant that has passed through the fuel cell flow path and the heat generating element flow path merges and flows into the cooler flow path. In this type of fuel cell cooling system, the refrigerant that has passed through the heat generating element flow path may flow back into the fuel cell flow path. When such a backflow occurs, the cooling efficiency of the fuel cell decreases. In addition, if a check valve is provided in the fuel cell flow path to suppress the backflow, the pressure loss in the fuel cell flow path increases, and the cooling efficiency of the fuel cell decreases. In this specification, a technology is proposed for suppressing the backflow of the refrigerant in the fuel cell flow path without decreasing the cooling efficiency of the fuel cell.

A fuel cell cooling system mounted on a vehicle, comprising a refrigerant flow path through which a refrigerant flows. The refrigerant flow path has a cooler flow path, a fuel cell flow path, and a heat generating element flow path. The upstream end of the fuel cell flow path and the upstream end of the heat generating element flow path are connected to a branching section provided at the downstream end of the cooler flow path. The downstream end of the fuel cell flow path and the downstream end of the heat generating element flow path are connected to a junction provided at the upstream end of the cooler flow path. The fuel cell cooling system further comprises a cooler that cools the refrigerant in the cooler flow path, a fuel cell that is cooled by heat exchange with the refrigerant in the fuel cell flow path, a heat generating element that generates heat during operation and is cooled by heat exchange with the refrigerant in the heat generating element flow path, a first pump that sends the refrigerant in the fuel cell flow path downstream, a second pump that sends the refrigerant in the heat generating element flow path downstream, a check valve interposed in the heat generating element flow path, and a control circuit that controls the first pump and the second pump. The control circuit maintains the first pump in an operating state while the vehicle is running. When the heating element is activated while the vehicle is running, the control circuit activates the second pump and increases the rotation speed of the first pump.

In this fuel cell cooling system, the control circuit maintains the first pump in an operating state while the vehicle is running. Therefore, the fuel cell is cooled by the refrigerant in the fuel cell flow path while the vehicle is running. In addition, when the heating element is activated while the vehicle is running, the control circuit activates the second pump. As a result, the refrigerant flows into the heating element flow path and cools the heating element. In addition, the control circuit activates the second pump and increases the rotation speed of the first pump. Therefore, even if the pressure of the refrigerant in the heating element flow path increases due to the operation of the second pump, it is possible to suppress the refrigerant from flowing back from the heating element flow path to the fuel cell flow path. In this way, in this fuel cell cooling system, it is possible to suppress the refrigerant from flowing back from the heating element flow path to the fuel cell flow path without providing a check valve in the fuel cell flow path. Therefore, in this fuel cell cooling system, it is possible to suppress the refrigerant from flowing back from the heating element flow path to the fuel cell flow path without reducing the cooling efficiency of the fuel cell.

FIG. 2 is a refrigerant circuit diagram showing the configuration of a fuel cell cooling system. 11 is a table illustrating a lower limit rotation speed R1min of the pump 21. 3 is a table illustrating a lower limit rotation speed R1min of the pump 21 in a system different from that in FIG. 2 . 11 is a table illustrating a lower limit rotation speed R1min of the pump 21 when temperature control is eliminated. 11 is a table illustrating an example of a lower limit rotation speed R1min of the pump 21 when a control rule is common between systems A and B.

In one example of a fuel cell cooling system disclosed herein, the control circuit may control the rotation speed of the first pump and the rotation speed of the second pump when operating the second pump while the vehicle is running, so that the pressure of the refrigerant at the downstream end of the fuel cell flow path is higher than the pressure of the refrigerant at the downstream end of the heating element flow path.

This configuration can more effectively prevent the coolant from flowing back into the fuel cell flow path.

The fuel cell cooling system of the example disclosed in this specification may further include a bypass flow passage having an upstream end connected to the cooler flow passage upstream of the cooler and a downstream end connected to the cooler flow passage downstream of the cooler, and a valve for adjusting the flow rate of the refrigerant flowing through the bypass flow passage. When the second pump is operated while the vehicle is traveling, the control circuit may adjust the rotation speed of the first pump according to the opening of the valve.

When a bypass flow path exists, the pressure loss in the coolant flow path changes depending on the flow rate of the coolant flowing through the bypass flow path (i.e., the valve opening), and the appropriate rotation speed of the first pump to suppress backflow changes. By adjusting the rotation speed of the first pump according to the valve opening as described above, it is possible to more effectively suppress backflow of coolant into the fuel cell flow path.

In one example of a fuel cell cooling system disclosed herein, when the second pump is operated while the vehicle is running, the control circuit may adjust the rotation speed of the first pump according to the temperature of the refrigerant.

The viscosity of the refrigerant changes depending on the temperature of the refrigerant, which changes the likelihood of the refrigerant backflowing into the fuel cell flow path. By adjusting the rotation speed of the first pump according to the temperature of the refrigerant as described above, the backflow of the refrigerant into the fuel cell flow path can be more effectively suppressed.

The fuel cell cooling system 10 of the embodiment shown in FIG. 1 is mounted on a vehicle. The fuel cell cooling system 10 has a fuel cell 12 (FC: Fuel Cell). The fuel cell 12 supplies power to a motor that drives the vehicle. The fuel cell cooling system 10 cools the fuel cell 12.

The fuel cell cooling system 10 has a refrigerant flow path 50 through which a refrigerant circulates. The refrigerant flow path 50 has a cooler flow path 52, a fuel cell flow path 54, a heating element flow path 56, and a bypass flow path 58.

The cooler flow path 52 extends from the junction 60 to the branching portion 62. The cooler flow path 52 has an upstream flow path 52a, a branching flow path 52b, a branching flow path 52c, and a downstream flow path 52d. The upstream end of the upstream flow path 52a is connected to the junction 60, which is the upstream end of the cooler flow path 52. The branching flow paths 52b and 52c are flow paths that branch into two downstream of the upstream flow path 52a. The downstream ends of the branching flow paths 52b and 52c are connected to the upstream end of the downstream flow path 52d. The downstream end of the downstream flow path 52d is connected to the branching portion 62, which is the downstream end of the cooler flow path 52. The refrigerant in the cooler flow path 52 flows from the junction 60, which is the upstream end, through the upstream flow path 52a, the branching flow paths 52b and 52c, and the downstream flow path 52d to the branching portion 62, which is the downstream end. In the branch flow paths 52b and 52c, the refrigerant is divided and flows into the branch flow paths 52b and 52c. A radiator 14 is provided in the branch flow path 52b. The radiator 14 cools the refrigerant flowing in the branch flow path 52b by heat exchange with the outside air. A radiator 16 is provided in the branch flow path 52c. The radiator 16 cools the refrigerant flowing in the branch flow path 52c by heat exchange with the outside air.

The upstream end of the bypass flow passage 58 is connected to the middle of the upstream flow passage 52a of the cooler flow passage 52. The downstream end of the bypass flow passage 58 is connected to the middle of the downstream flow passage 52d of the cooler flow passage 52. A rotary valve 20 is provided at the connection between the bypass flow passage 58 and the upstream flow passage 52a. Hereinafter, the part of the upstream flow passage 52a that is upstream of the rotary valve 20 is referred to as the first part 52a-1, and the part downstream of the rotary valve 20 is referred to as the second part 52a-2. The rotary valve 20 changes the flow rate of the refrigerant flowing from the first part 52a-1 to the bypass flow passage 58 and the flow rate of the refrigerant flowing from the first part 52a-1 to the second part 52a-2. When the opening degree S of the rotary valve 20 is 100%, all of the refrigerant flowing in the first part 52a-1 flows to the second part 52a-2. When the opening degree S of the rotary valve 20 is 50%, half of the refrigerant flowing in the first portion 52a-1 flows to the second portion 52a-2, and the remaining half of the refrigerant flowing in the first portion 52a-1 flows to the bypass flow path 58. When the opening degree S of the rotary valve 20 is 0%, all of the refrigerant flowing in the first portion 52a-1 flows to the bypass flow path 58. An ion exchanger 18 is installed in the bypass flow path 58. The ion exchanger 18 removes ions from the refrigerant flowing in the bypass flow path 58. Ions are eluted from the piping and the like that constitute the refrigerant flow path 50 into the refrigerant. By flowing the refrigerant through the bypass flow path 58 (i.e., the ion exchanger 18), the ion concentration in the solvent can be reduced.

The upstream ends of the fuel cell flow path 54 and the heating element flow path 56 are connected to the downstream end of the cooler flow path 52 at the branching section 62. The downstream ends of the fuel cell flow path 54 and the heating element flow path 56 are connected to the upstream end of the cooler flow path 52 at the junction section 60.

A pump 21 is interposed in the fuel cell flow path 54. The pump 21 sends the refrigerant in the fuel cell flow path 54 downstream. Downstream of the pump 21, the fuel cell flow path 54 branches into branch flow paths 54a and 54b. The fuel cell 12 is installed in the branch flow path 54a. The fuel cell 12 is cooled by heat exchange with the refrigerant flowing in the branch flow path 54a. The intercooler 24 is installed in the branch flow path 54b. The intercooler 24 is cooled by heat exchange with the refrigerant flowing in the branch flow path 54b.

The heating element flow path 56 is provided with a pump 22, a brake resistor 28 (BR), and a check valve 30. The pump 22 sends the refrigerant in the heating element flow path 56 downstream. The brake resistor 28 is provided downstream of the pump 22. The brake resistor 28 may be called an excess power heater or an electric heater. When the vehicle motor performs a regenerative operation while the battery is fully charged, the brake resistor 28 converts the excess power generated by the regenerative operation into thermal energy and consumes it. The brake resistor 28 is cooled by heat exchange with the refrigerant in the heating element flow path 56. The check valve 30 is provided downstream of the brake resistor 28. The check valve 30 prevents the refrigerant from flowing backward in the heating element flow path 56.

The fuel cell cooling system 10 has an integrated ECU 70 (integrated electronic control unit) and an EV-ECU 72 (electric vehicle-electronic control unit) as control circuits. The EV-ECU 72 controls the brake resistor 28, etc. The integrated ECU 70 controls the pumps 21, 22, the fuel cell 12, etc.

Although not shown, the fuel cell cooling system 10 also has a temperature sensor that detects the temperature of the refrigerant. The temperature sensor is installed at any position in the refrigerant flow path 50.

Next, the operation of the fuel cell cooling system 10 will be described. When the vehicle starts, the integrated ECU 70 operates the fuel cell 12 to generate electricity. The vehicle runs on the power generated by the fuel cell 12. While the vehicle is running, the integrated ECU 70 continues to operate the fuel cell 12. In addition, when the vehicle starts, the integrated ECU 70 operates the pump 21. While the vehicle is running, the integrated ECU 70 maintains the pump 21 in an operating state. When the pump 21 operates, a refrigerant flows through the circulation flow path formed by the fuel cell flow path 54 and the cooler flow path 52. The refrigerant flowing through this circulation flow path is cooled by the radiators 14 and 16. Therefore, the refrigerant cooled by the radiators 14 and 16 flows into the fuel cell flow path 54 (particularly the branch flow path 54a), and the fuel cell 12 is cooled. Therefore, the fuel cell 12 is prevented from becoming excessively hot. The integrated ECU 70 controls the rotation speed R1 of the pump 21 according to the temperature of the fuel cell 12, etc. For example, the higher the temperature of the fuel cell 12, the higher the rotation speed R1 of the pump 21 is set by the integrated ECU 70. This allows the temperature of the fuel cell 12 to be appropriately controlled. When the pump 21 is operating while the pump 22 is stopped, the check valve 30 closes to prevent the refrigerant from flowing from the downstream end 54e of the fuel cell flow path 54 into the heating element flow path 56. In other words, the check valve 30 closes to prevent the refrigerant from flowing back in the heating element flow path 56.

When the refrigerant is circulating in the circulation flow path formed by the fuel cell flow path 54 and the cooler flow path 52, the integrated ECU 70 controls the opening degree S of the rotary valve 20 to cause some or all of the refrigerant that has passed through the first portion 52a-1 of the cooler flow path 52 to flow into the bypass flow path 58. As a result, the integrated ECU 70 executes an ion removal process that removes ions in the refrigerant using the ion exchanger 18. The integrated ECU 70 executes the ion removal process when the ion concentration in the refrigerant increases.

When the vehicle motor performs a regenerative operation while the battery is fully charged, the EV-ECU 72 activates the brake resistor 28. This causes the brake resistor 28 to consume excess power generated by the motor. When the brake resistor 28 activates, the brake resistor 28 generates heat. When the EV-ECU 72 activates the brake resistor 28, it sends this information to the integrated ECU 70. When the brake resistor 28 activates, the integrated ECU 70 activates the pump 22. When the pump 22 operates, the check valve 30 opens, and the refrigerant in the heating element flow path 56 flows downstream. Therefore, the refrigerant that has flowed through the cooler flow path 52 to the branching portion 62 branches into the fuel cell flow path 54 and the heating element flow path 56 and flows there. The refrigerant that has passed through the fuel cell flow path 54 and the heating element flow path 56 merge at the merging portion 60 and flow into the cooler flow path 52. When the coolant flows through the heating element flow path 56, the coolant in the heating element flow path 56 cools the brake resistor 28. This prevents the brake resistor 28 from becoming excessively hot. The integrated ECU 70 also controls the rotation speed R2 of the pump 22 according to the temperature of the brake resistor 28, etc. For example, the higher the temperature of the brake resistor 28, the higher the rotation speed R2 of the pump 22 is set by the integrated ECU 70. This allows the temperature of the brake resistor 28 to be appropriately controlled.

When the pump 22 is operated, the pressure of the refrigerant at the downstream end 56e of the heating element flow path 56 increases. When the pressure of the refrigerant at the downstream end 56e of the heating element flow path 56 becomes higher than the pressure of the refrigerant at the downstream end 54e of the fuel cell flow path 54, the refrigerant flows into the fuel cell flow path 54 from the downstream end 56e of the heating element flow path 56. That is, a backflow of the refrigerant occurs in the fuel cell flow path 54. A high-temperature refrigerant that has passed through the brake resistor 28 flows into the downstream end 56e of the heating element flow path 56. Therefore, when the refrigerant flows into the fuel cell flow path 54 from the downstream end 56e of the heating element flow path 56, a high-temperature refrigerant is supplied to the fuel cell 12. This inhibits the cooling of the fuel cell 12. In order to prevent such a backflow of the refrigerant, the integrated ECU 70 adjusts the rotation speed R1 of the pump 21 according to the rotation speed R2 of the pump 22.

Figure 2 shows the control rules for the rotation speed R1 of the pump 21 stored in the integrated ECU 70. Each table in Figure 2 shows the lower limit rotation speed R1min of the pump 21. The integrated ECU 70 operates the pump 21 at a rotation speed R1 higher than the lower limit rotation speed R1min shown in Figure 2. Figure 2(a) shows the control rules when the refrigerant temperature T (the temperature of the refrigerant detected by the temperature sensor not shown in the figure) is 60°C, Figure 2(b) shows the control rules when the refrigerant temperature T is 25°C, and Figure 2(c) shows the control rules when the refrigerant temperature T is -10°C. As shown in each table in Figure 2, the lower limit rotation speed R1min of the pump 21 is determined according to the refrigerant temperature T, the opening degree S of the rotary valve 20, and the rotation speed R2 of the pump 22. The lower limit rotation speed R1min for each condition in FIG. 2 is set so that the pressure of the refrigerant at the downstream end 54e of the fuel cell flow path 54 is higher than the pressure of the refrigerant at the downstream end 56e of the heating element flow path 56.

For example, as shown in FIG. 2(b), when the rotation speed R2 of the pump 22 is 800 rpm, the lower limit rotation speed R1min of the pump 21 is 0 rpm, regardless of the opening degree S of the rotary valve 20. Therefore, when the pump 22 is stopped (i.e., when the brake resistor 28 is stopped), the lower limit rotation speed R1min of the pump 21 is 0 rpm. Also, as shown in FIG. 2(b), when the rotation speed R2 of the pump 22 is 1500 rpm and the opening degree S of the rotary valve 20 is 0%, the lower limit rotation speed R1min of the pump 21 is 594 rpm. Note that when the rotation speed R2 is a value between the values shown in the table of FIG. 2, the lower limit rotation speed R1min is calculated by interpolation based on the table of FIG. 2. 2B, when the brake resistor 28 is activated and the pump 22 starts to operate at a rotation speed R2 of 1500 rpm, the integrated ECU 70 increases the lower limit rotation speed of the pump 21 from 0 rpm to 594 rpm. Therefore, if the rotation speed R1 of the pump 21 is less than 594 rpm (e.g., 400 rpm) before the brake resistor 28 is activated, the integrated ECU 70 increases the rotation speed R1 of the pump 21 to a value equal to or greater than 594 rpm. In this way, by increasing the rotation speed R1 of the pump 21 when the pump 22 starts to operate, the pressure of the refrigerant at the downstream end 54e of the fuel cell flow path 54 can be increased. Therefore, the pressure of the refrigerant at the downstream end 56e of the heating element flow path 56 can be prevented from becoming higher than the pressure of the refrigerant at the downstream end 54e of the fuel cell flow path 54. Therefore, the backflow of the refrigerant in the fuel cell flow path 54 can be prevented. This allows the fuel cell 12 to be properly cooled even when the pump 22 is operating.

In this way, when the pump 22 starts to operate at a predetermined rotation speed R2 while the vehicle is running, the lower limit rotation speed R1min of the pump 21 rises to a value corresponding to the rotation speed R2 of the pump 22. Therefore, when the rotation speed R1 of the pump 21 is lower than the raised lower limit rotation speed R1min, the integrated ECU 70 raises the rotation speed R1 to a value higher than the lower limit rotation speed R1min. This prevents backflow of the refrigerant in the fuel cell flow path 54. In this way, according to the fuel cell cooling system 10, backflow of the refrigerant in the fuel cell flow path 54 is prevented without providing a check valve in the fuel cell flow path 54. Therefore, backflow of the refrigerant in the fuel cell flow path 54 is prevented without increasing the pressure loss in the fuel cell flow path 54. Therefore, backflow of the refrigerant in the fuel cell flow path 54 is prevented without reducing the cooling efficiency of the fuel cell 12. Although the check valve 30 is provided in the heating element flow path 56, the required cooling performance for the brake resistor 28 is not as high as the required cooling performance for the fuel cell 12, so there is no problem with providing the check valve 30 in the heating element flow path 56. Also, by providing the check valve 30 in the heating element flow path 56, it is possible to prevent backflow of the refrigerant in the heating element flow path 56 without operating the pump 22 while the brake resistor 28 is stopped. This makes it possible to reduce power consumption in the pump 22.

Also, as shown in each table in FIG. 2, the higher the rotation speed R2 of the pump 22, the higher the lower limit rotation speed R1min of the pump 21. In this way, by setting the lower limit rotation speed R1min of the pump 21, the rotation speed R1 of the pump 21 can be appropriately controlled within a range in which the refrigerant does not flow back. This prevents the rotation speed R1 of the pump 21 from increasing more than necessary.

As shown in each table in FIG. 2, the lower limit rotation speed R1min of the pump 21 varies depending on the opening degree S of the rotary valve 20. When the opening degree S of the rotary valve 20 changes, the pressure loss in the refrigerant flow path changes, and the appropriate lower limit rotation speed R1min of the pump 21 changes. Therefore, by varying the lower limit rotation speed R1min of the pump 21 depending on the opening degree S of the rotary valve 20, the rotation speed R1 of the pump 21 can be more appropriately controlled within a range in which backflow of the refrigerant does not occur.

As shown in each table in FIG. 2, the lower limit rotation speed R1min of the pump 21 varies depending on the temperature T. For example, when the opening degree S is 0% and the rotation speed R2 is 2500 rpm, the lower limit rotation speed R1min is 1400 rpm when the temperature T is 60°C, 1433 rpm when the temperature T is 25°C, and 1393 rpm when the temperature T is -10°C. When the temperature T changes, the viscosity of the refrigerant changes, and the pressure loss in the refrigerant flow path changes. Therefore, by varying the lower limit rotation speed R1min of the pump 21 depending on the temperature T, the rotation speed R1 of the pump 21 can be more appropriately controlled within a range in which the refrigerant does not flow back.

Also, FIG. 3 shows the lower limit rotation speed R1min of the pump 21 in a system different from that in FIG. 2. That is, FIG. 2 shows the control rules for system A, which is an example of the fuel cell cooling system 10, and FIG. 3 shows the control rules for system B, which is another example of the fuel cell cooling system 10. In each table in FIG. 3, the lower limit rotation speed R1min of the pump 21 is set for each temperature T, opening S, and rotation speed R2, as in each table in FIG. 2. The arrangement of some piping is different between system A and system B, and the pressure loss in the flow path of the refrigerant is different. Therefore, the lower limit rotation speed R1min in each table in FIG. 3 is different from the lower limit rotation speed R1min in each table in FIG. 2. According to the control rules in FIG. 3, it is possible to prevent backflow of the refrigerant in the fuel cell flow path 54 of system B.

As described above, the pump 21 can be controlled more appropriately by setting the lower limit rotation speed R1min of the pump 21 according to the opening degree S of the rotary valve 20, the rotation speed R2 of the pump 22, the temperature T of the refrigerant, and the system.

In order to simplify the control rules, it is not necessary to control the lower limit rotation speed R1min according to the temperature T. In this case, the lower limit rotation speed R1min may be set as shown in FIG. 4 by extracting the maximum value of the lower limit rotation speed R1min for each condition in FIGS. 2(a) to (c). According to the control rules in FIG. 4, if the temperature T is within the range of −10 to 60° C., backflow of the refrigerant in the fuel cell flow path 54 can be prevented without changing the lower limit rotation speed R1min according to the temperature T. In addition to simplifying the control rules according to the temperature T, the control method in systems A and B may be made common. In this case, the lower limit rotation speed R1min may be set as shown in FIG. 5 by extracting the maximum value of the lower limit rotation speed R1min for each condition in the tables in FIGS. 2 and 3. The control rules in FIG. 5 can prevent backflow of the refrigerant in both systems A and B.

The flow rate may be specified by estimating the system state so that the pressure of the refrigerant at the downstream end 54e of the fuel cell flow path 54 is higher than the pressure of the refrigerant at the downstream end 56e of the heating element flow path 56, and a lower flow rate limit may be set to prevent the refrigerant from flowing backwards, and the pump rotation speed may be controlled.

In the above embodiment, the heating element installed in the heating element flow path 56 was the brake resistor 28, but another heating element may be installed in the heating element flow path 56.

In the above embodiment, the flow rate of the refrigerant flowing through the bypass flow passage 58 is controlled by the rotary valve 20 provided at the connection between the upstream end of the bypass flow passage 58 and the cooler flow passage 52. However, the flow rate of the refrigerant flowing through the bypass flow passage 58 may be controlled by another valve provided midway through the bypass flow passage 58 or at the connection between the downstream end of the bypass flow passage 58 and the cooler flow passage 52. In this case, the lower limit rotation speed R1min can be set according to the opening degree of that valve.

In addition, in the above-described embodiment, the ion exchanger 18 is installed in the bypass flow path 58. However, other devices may be installed in the bypass flow path 58 instead of the ion exchanger 18.

In addition, in the above-described embodiment, the pump 21 is disposed upstream of the fuel cell 12 in the fuel cell flow path 54, but the pump 21 may be disposed downstream of the fuel cell 12. In addition, in the above-described embodiment, the pump 22, the brake resistor 28, and the check valve 30 are disposed in this order from the upstream side in the heating element flow path 56, but the order of these devices may be different.

Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples given above. The technical elements described in this specification or drawings demonstrate technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

10: Fuel cell cooling system 12: Fuel cell 14: Radiator 16: Radiator 18: Ion exchanger 20: Rotary valve 21: Pump 22: Pump 24: Intercooler 28: Brake resistor 30: Check valve 50: Coolant flow path 52: Cooler flow path 54: Fuel cell flow path 56: Heating element flow path 58: Ion exchanger flow path

Claims (4)

A fuel cell cooling system mounted on a vehicle,
It has a refrigerant flow path inside,
The coolant flow path includes a cooler flow path, a fuel cell flow path, and a heating element flow path,
an upstream end of the fuel cell flow path and an upstream end of the heat generating element flow path are connected to a branch portion provided at a downstream end of the cooler flow path,
a downstream end of the fuel cell flow path and a downstream end of the heat generating element flow path are connected to a junction provided at an upstream end of the cooler flow path,
a cooler that cools the refrigerant in the cooler flow path;
a fuel cell that is cooled by heat exchange with the coolant in the fuel cell flow path;
A heating element that generates heat during operation and is cooled by heat exchange with the refrigerant in the heating element flow path;
a first pump that pumps the coolant in the fuel cell flow path downstream;
a second pump that pumps the coolant in the heating element flow path downstream;
A check valve interposed in the heating element flow path;
a control circuit for controlling the first pump and the second pump;
and
The control circuit maintains the first pump in an actuated state while the vehicle is running,
When the heating element is activated while the vehicle is running, the control circuit operates the second pump and increases the rotation speed of the first pump.
Fuel cell cooling system. The fuel cell cooling system of claim 1, wherein the control circuit controls the rotation speed of the first pump and the rotation speed of the second pump so that the pressure of the refrigerant at the downstream end of the fuel cell flow path is higher than the pressure of the refrigerant at the downstream end of the heating element flow path when the second pump is operated while the vehicle is running. a bypass flow path having an upstream end connected to the cooler flow path upstream of the cooler and a downstream end connected to the cooler flow path downstream of the cooler;
a valve for adjusting a flow rate of the refrigerant flowing through the bypass flow path;
and
3. The fuel cell cooling system according to claim 1, wherein when the second pump is operated while the vehicle is running, the control circuit adjusts the rotation speed of the first pump in accordance with an opening degree of the valve. A fuel cell cooling system as described in any one of claims 1 to 3, wherein when the second pump is operated while the vehicle is running, the control circuit adjusts the rotation speed of the first pump in accordance with the temperature of the refrigerant.

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