Cooling system

Abstract

The cooling system S is provided with: a first pump 13 provided downstream of the radiator 10 and upstream of the FC stack 11 in the cooling flow path 1; a regulating valve (14) that regulates a first flow rate of cooling water flowing from the radiator (10) to the first pump (13) and a second flow rate of cooling water flowing from the first branch flow path (2) to the first pump (13); a second pump 23 provided in the second branch flow path 3; and a controller 30 that determines a first delivery amount of the first pump 13 on the basis of the degree of adjustment of the adjustment valve 14 and the temperature of the FC stack 11, and determines a second delivery amount of the second pump 23 on the basis of the degree of adjustment and the first delivery amount.

Description

Technical Field

[0001] The present disclosure relates to cooling systems. Background Art

[0002] A conventional cooling system adjusts a first flow rate of cooling water flowing through a first flow path provided for cooling a fuel cell stack based on a second flow rate of cooling water flowing through a second flow path provided for cooling a brake resistor (eg, Japanese Unexamined Patent Application Publication No. 2023-12332). Summary of the Invention

[0003] Problems to be solved by the present invention

[0004] In a conventional cooling system, a cooling flow path branches into a first flow path and a second flow path at a branch point downstream of a radiator. The cooling flow paths merge at a confluence point downstream of a pump provided in each of the first and second flow paths, and then return to the radiator downstream of the confluence point, thereby circulating the cooling water. However, when the second flow rate of the cooling water flowing through the second flow path is higher than the first flow rate of the cooling water flowing through the first flow path, the cooling water flowing through the second flow path may flow back into the first flow path, and thus may not properly cool the fuel cell stack.

[0005] The present disclosure has been made in consideration of these points, and its object is to appropriately cool a fuel cell stack.

[0006] Means used to solve problems

[0007] A cooling system according to an aspect of the present disclosure includes: a cooling flow path that circulates cooling water between a radiator and a fuel cell stack; a first pump that is disposed in the cooling flow path downstream of the radiator and upstream of the fuel cell stack and delivers the cooling water; a first branch flow path that branches from downstream of the fuel cell stack in the cooling flow path, bypasses the radiator, and merges with the cooling flow path at a first confluence point upstream of the first pump; a regulating valve that is disposed at the first confluence point in the cooling flow path and adjusts a first flow rate of the cooling water flowing from the radiator to the first pump and a second flow rate of the cooling water flowing from the first branch flow path to the first pump; a second branch flow path that branches from a branch point upstream of the regulating valve in the cooling flow path and merges with the cooling flow path at a second confluence point downstream of the fuel cell stack; a braking resistor disposed in the second branch flow path; a second pump that is disposed in the second branch flow path upstream of the braking resistor and delivers the cooling water; and a controller that determines a first delivery amount of the first pump based on (i) a degree of adjustment of the first and second flow rates of the regulating valve and (ii) a temperature of the fuel cell stack, and determines a second delivery amount of the second pump based on the degree of adjustment and the first delivery amount.

[0008] The cooling system may further include: a first check valve, which is disposed downstream of a branch point between the cooling flow path and the first branch flow path in the cooling flow path and upstream of a second confluence point in the cooling flow path.

[0009] The cooling system may further include: a second check valve, which is disposed downstream of the braking resistor in the second branch flow path and upstream of the second confluence point in the second branch flow path.

[0010] The cooling system may further include: a three-way valve, which is disposed at the second confluence point and prevents the cooling water from flowing back in the cooling flow path and the second branch flow path.

[0011] The higher the temperature of the cooling water at the first confluence point is, the more the regulating valve can increase the first flow rate and decrease the second flow rate.

[0012] The larger the first flow rate corresponding to the degree of regulation is, the more the controller can increase the first delivery amount.

[0013] The higher the temperature of the fuel cell stack is, the more the controller can increase the first delivery amount.

[0014] The controller may determine a second delivery amount based on the determined first delivery amount, the degree of regulation, and the temperature of the braking resistor.

[0015] In a state where the braking resistor is operating, the higher the temperature of the braking resistor is, the more the controller can increase the second delivery amount.

[0016] When the braking resistor is not operating, the controller may determine the second delivery amount to be greater than 0 and less than the first delivery amount.

[0017] The controller may determine the first delivery amount and the second delivery amount by referring to a delivery amount map stored in a memory, and the delivery amount map indicates the degree of regulation, the state of whether the braking resistor is operating, the first delivery amount corresponding to the temperature of the fuel cell stack, and the second delivery amount corresponding to the first delivery amount.

[0018] When the braking resistor is not operating, after determining the first delivery amount based on the degree of regulation and the temperature of the fuel cell stack, the controller may determine a first relative ratio for determining a second delivery amount smaller than the first delivery amount based on the degree of regulation, and determine the multiplication value obtained by multiplying the first delivery amount by the first relative ratio as the second delivery amount, and the first relative ratio is the ratio of the second delivery amount to the first delivery amount.

[0019] The regulating valve may have a first valve for regulating the first flow rate, and the larger the valve opening degree of the first valve included in the degree of regulation is, the more the controller can decrease the first relative ratio. <{

[0020] When the braking resistor operates, after determining the first delivery amount based on the adjustment degree and the temperature of the fuel cell stack, the controller may determine a second relative ratio for determining a second delivery amount larger than the first delivery amount based on the adjustment degree, and determine the multiplication value obtained by multiplying the first delivery amount by the second relative ratio as the second delivery amount, where the second relative ratio is the ratio of the second delivery amount to the first delivery amount.

[0021] The regulating valve may have a second valve for regulating the second flow rate, and included in the adjustment degree, the larger the valve opening degree of the second valve, the more the controller may increase the second relative ratio, and the higher the temperature of the braking resistor, the more the controller may increase the second relative ratio.

[0022] Effects of the present invention

[0023] According to the present disclosure, the fuel cell stack can be appropriately cooled. Description of the drawings

[0024] Figure 1 is a diagram schematically showing the configuration of the cooling system S according to the present embodiment.

[0025] Figure 2 is a diagram schematically showing the configuration of the cooling system S provided with a check valve.

[0026] Figure 3 is a diagram schematically showing the configuration of the cooling system S provided with a three-way valve.

[0027] Figure 4 is a diagram showing an example of the processing sequence in the controller 30.

[0028] Figure 5 is a diagram showing an example of the delivery amount map stored in the memory. Detailed description of the invention

[0029] <Configuration of the cooling system S>

[0030] Figure 1 is a diagram schematically showing the configuration of the cooling system S according to the present embodiment. Figure 1 The cooling system S shown in includes a cooling flow path 1, a first branch flow path 2, a second branch flow path 3, a radiator 10, a fuel cell stack 11, a first temperature sensor 12, a first pump 13, a regulating valve 14, a braking resistor 21, a second temperature sensor 22, a second pump 23, and a controller 30.

[0031] The cooling system S is mounted on a vehicle and is used to cool the fuel cell stack 11 and the braking resistor 21 by promoting heat exchange between the fuel cell stack 11 and the braking resistor 21 and the cooling water. First, each flow path through which the cooling water flows will be described.

[0032] The cooling flow path 1 is a flow path designed to circulate cooling water between the radiator 10 and the fuel cell stack 11 to cool the fuel cell stack 11. In the cooling flow path 1, the radiator 10, the regulating valve 14, the first pump 13, and the fuel cell stack 11 are arranged along the circulation direction D1 of the cooling water.

[0033] As indicated by Figure 1 the dashed line in, the first branch flow path 2 branches from a first branch point 4 on the downstream side of the fuel cell stack 11 in the cooling flow path 1, bypasses the radiator 10, and joins the cooling flow path 1 at a first confluence point (not shown) on the upstream side of the first pump 13. As Figure 1 shown in, the regulating valve 14 is provided at the first confluence point. Figure 1 The direction D2 shown in is the direction in which the cooling water flows in the first branch flow path 2. Since the first branch flow path 2 is arranged in this way, when the fuel cell stack 11 does not require cooling, the cooling system S can cause the cooling water that has not undergone heat exchange with the radiator 10 to flow to the fuel cell stack 11.

[0034] The second branch flow path 3 is a flow path designed to cool the braking resistor 21. As indicated by Figure 1 the single-dot chain line in, the second branch flow path 3 branches from a second branch point 5 on the upstream side of the regulating valve 14 in the cooling flow path 1, and joins the cooling flow path 1 at a second confluence point 6 on the downstream side of the fuel cell stack 11. In the second branch flow path 3, the second pump 23 and the braking resistor 21 are arranged along the flow direction D3 of the cooling water. Next, each component provided in each flow path will be described.

[0035] The radiator 10 is provided on the upstream side of the regulating valve 14 in the cooling flow path 1, and cools the cooling water that has passed through at least one of the fuel cell stack 11 or the braking resistor 21. For example, the radiator 10 cools the cooling water through heat exchange between the cooling water and the wind (traveling wind) flowing from the front of the vehicle on which the cooling system S is installed. The radiator 10 may be provided with a fan that promotes the inflow of wind from the front of the vehicle.

[0036] The fuel cell stack 11 is a module in which a plurality of fuel cells are stacked, and is provided downstream of the first pump 13 in the cooling flow path 1. For example, the fuel cell stack 11 generates electricity through a chemical reaction between (i) a fuel gas (such as hydrogen) and (ii) an oxidant gas (such as oxygen in the air), and supplies the generated electricity to a drive source (for example, an electric motor) included in a vehicle equipped with the cooling system S. In the following description, the fuel cell stack 11 is referred to as the FC stack 11.

[0037] The first temperature sensor 12 is a sensor that detects the temperature of the FC stack 11 and outputs the detected temperature to the controller 30. The first pump 13 is disposed in the cooling flow path 1 downstream of the radiator 10 and upstream of the FC stack 11 and conveys cooling water. For example, the first pump 13 includes a rotor, obtains a first rotational speed corresponding to a first conveyance amount from the controller 30, sucks cooling water by rotating the rotor at the first rotational speed, and discharges the sucked cooling water to the FC stack 11. The first conveyance amount is the amount of cooling water discharged to the FC stack 11 by the first pump 13 per unit time.

[0038] The regulating valve 14 is provided at the first confluence point in the cooling flow path 1 and regulates a first flow rate of the cooling water flowing from the radiator 10 to the first pump 13 and a second flow rate of the cooling water flowing from the first branch flow path 2 to the first pump 13. For example, the regulating valve 14 is a temperature automatic regulator and includes a first valve for regulating the first flow rate, a second valve for regulating the second flow rate, and a thermistor for detecting the temperature of the cooling water at the first confluence point. The first valve and the second valve are adjusted such that the opening degree of one of the valves increases as the opening degree of the other valve decreases. For example, the thermistor is provided at the discharge port of the regulating valve 14.

[0039] For example, the regulating valve 14 determines the valve opening degrees of the first valve and the second valve based on the temperature detected by the thermistor to adjust the ratio of the first flow rate to the second flow rate in the flow rate of the cooling water flowing through the first pump 13. Specifically, the higher the temperature of the cooling water at the first confluence point, the more the regulating valve 14 increases the first flow rate and decreases the second flow rate. That is, the higher the temperature detected by the thermistor, the more the regulating valve 14 increases the valve opening degree of the first valve and decreases the valve opening degree of the second valve. On the other hand, the lower the temperature detected by the thermistor, the more the regulating valve 14 decreases the valve opening degree of the first valve and increases the valve opening degree of the second valve. The regulating valve 14 outputs the adjustment degree indicating the determined valve opening degrees of the first valve and the second valve (i.e., the ratio of the first flow rate to the second flow rate) to the controller 30.

[0040] Since the regulating valve 14 operates in this manner, the cooling system S can promote the heat exchange between (i) the cooling water cooled by heat exchange with the radiator 10 and (ii) the FC stack 11 by increasing the first flow rate as the temperature of the cooling water downstream of the regulating valve 14 becomes higher. On the other hand, in the cooling system S, as the temperature of the cooling water downstream of the regulating valve 14 becomes lower, the cooling water that has not undergone heat exchange with the radiator 10 can flow to the FC stack 11, and thus overcooling of the FC stack 11 can be prevented.

[0041] In addition, in the cooling system S, since the larger the second flow rate (the smaller the first flow rate), the larger the third flow rate of the cooling water flowing from the radiator 10 to the second pump 23 becomes, the heat exchange between (i) the cooling water cooled by heat exchange with the radiator 10 and (ii) the braking resistor 21 can be promoted. Since the larger the third flow rate, the larger the flow rate of the cooling water flowing from the second branch flow path 3 at the second confluence point 6 becomes, the cooling water is more likely to remain upstream of the second confluence point 6 and downstream of the first branch point 4. As a result, the larger the third flow rate, the larger the second flow rate of the cooling water branched to the first branch flow path 2 at the first branch point 4 becomes.

[0042] For example, the braking resistor 21 is a brake such as a speed reducer and is provided in the second branch flow path 3. When instruction information indicating a braking command for the vehicle is obtained from the controller 30, the braking resistor 21 brakes the vehicle. The second temperature sensor 22 is a sensor that detects the temperature of the braking resistor 21 and outputs the detected temperature to the controller 30.

[0043] The second pump 23 is provided upstream of the braking resistor 21 in the second branch flow path 3 and conveys the cooling water. For example, the second pump 23 includes a rotor, obtains a second rotational speed corresponding to the second conveyance amount from the controller 30, sucks the cooling water by rotating the rotor at the second rotational speed, and discharges the sucked cooling water to the braking resistor 21. The second conveyance amount is the amount of cooling water discharged to the braking resistor 21 by the second pump 23 per unit time.

[0044] For example, the controller 30 is a device including one or more processors such as a central processing unit (CPU) or an electronic control unit (ECU). The controller 30 performs processing, and the processing performed by the controller 30 includes: when a deceleration or stop operation is received from the driver of the vehicle, causing the braking resistor 21 to brake the vehicle; and causing the first pump 13 and the second pump 23 to convey the cooling water by determining the first conveyance amount and the second conveyance amount, thereby cooling the FC stack 11 and the braking resistor 21. The controller 30 may include a housing containing electronic components, or may be a printed substrate on which electronic components are mounted.

[0045] For example, the conventional controller 30 determines the first conveyance amount corresponding to the subtraction value obtained by subtracting the target temperature of the FC stack 11 from the temperature detected by the first temperature sensor 12, and outputs the first rotational speed of the rotor corresponding to the first conveyance amount to the first pump 13. Then, the controller 30 determines the second rotational speed of the rotor corresponding to the second conveyance amount based on the first rotational speed of the rotor, and outputs the second rotational speed to the second pump 23.

[0046] In the above-described normal operation, when the control valve 14 reduces the first flow rate and the controller 30 increases the second rotational speed, the flow rate of the cooling water flowing from the second branch flow path 3 to the second confluence point 6 may become greater than the flow rate of the cooling water flowing from the first branch point 4 to the second confluence point 6. In this case, if the flow rate of the cooling water flowing from the first branch point 4 to the second confluence point 6 is extremely low, the cooling water flowing from the second branch flow path 3 to the second confluence point 6 may flow back from the second confluence point 6 to the first branch point 4 instead of flowing in the direction D4 from the second confluence point 6. Therefore, in the present embodiment, the controller 30 determines the first delivery amount of the first pump 13 based on (i) the adjustment degree of the first flow rate and the second flow rate of the control valve 14 and (ii) the temperature of the FC stack 11, and determines the second delivery amount of the second pump 23 based on the adjustment degree and the first delivery amount.

[0047] For example, the greater the first flow rate corresponding to the adjustment degree obtained from the control valve 14, the more the controller 30 increases the first delivery amount. In addition, for example, the higher the temperature of the FC stack 11 detected by the first temperature sensor 12, the more the controller 30 increases the first delivery amount. Next, the controller 30 determines, for example, the first relative ratio of the second delivery amount to the first delivery amount based on the adjustment degree, and determines the multiplication value obtained by multiplying the first delivery amount by the first relative ratio as the second delivery amount.

[0048] The first relative ratio is a relative ratio for determining the second delivery amount (which is less than the first delivery amount), and represents a value greater than 0 and less than 100 when expressed as a percentage. For example, the greater the valve opening degree of the first valve included in the adjustment degree, the more the controller 30 reduces the first relative ratio.

[0049] Then, the controller 30 outputs the first rotational speed corresponding to the determined first delivery amount to the first pump 13, and outputs the second rotational speed corresponding to the determined second delivery amount to the second pump 23. Since the controller 30 operates in this manner, the controller 30 can make the second delivery amount less than the first delivery amount, and thus can make the flow rate of the cooling water flowing from the second branch flow path 3 to the second confluence point 6 less than the flow rate of the cooling water flowing from the first branch point 4 to the second confluence point 6. As a result, since the controller 30 can prevent the cooling water from flowing back from the second confluence point 6 to the first branch point 4, the cooling system S can appropriately cool the FC stack 11.

[0050] In a case where the electric motor is included in a drive source of a vehicle on which the cooling system S is mounted, when the vehicle accelerates, the FC stack 11 that generates electricity to be supplied to the electric motor generates heat, but the braking resistor 21 does not generate heat. On the other hand, when the vehicle decelerates or stops, the braking resistor 21 that operates to brake the vehicle generates heat, but the FC stack 11 does not generate heat. That is, when the vehicle is running, when one of the FC stack 11 and the braking resistor 21 operates and generates heat, the other does not operate and thus does not generate heat.

[0051] Therefore, the controller 30 can determine the first delivery amount and the second delivery amount based on the state of whether the braking resistor 21 operates. For example, when the braking resistor 21 does not operate, the controller 30 determines the first delivery amount based on the adjustment degree of the regulating valve 14 and the temperature of the FC stack 11. Then, for example, the controller 30 determines the second delivery amount by multiplying the determined first delivery amount by a first relative ratio corresponding to the adjustment degree, thereby determining the second delivery amount that is greater than 0 and less than the first delivery amount.

[0052] For example, when the braking resistor 21 does not operate, after determining the first delivery amount based on the adjustment degree of the regulating valve 14 and the temperature of the FC stack 11, the controller 30 determines a first relative ratio (which is the ratio of the second delivery amount to the first delivery amount) for determining the second delivery amount that is smaller than the first delivery amount based on the adjustment degree, and determines the multiplication value obtained by multiplying the first delivery amount by the first relative ratio as the second delivery amount. Since the controller 30 operates in this way, the cooling system S can cause the cooling water to flow to the FC stack 11 and cause the cooling water to flow from the second branch flow path 3 to the radiator 10, and thus can appropriately cool the FC stack 11 and cool the cooling water.

[0053] For example, when the braking resistor 21 operates, after determining the first delivery amount based on the adjustment degree and the temperature of the FC stack 11, the controller 30 determines the second delivery amount based on the determined first delivery amount, the adjustment degree, and the temperature of the braking resistor 21. For example, the greater the second flow rate corresponding to the adjustment degree, the more the controller 30 increases the second delivery amount, and the higher the temperature of the braking resistor 21, the more the controller 30 increases the second delivery amount.

[0054] For example, when the braking resistor 21 operates, the controller 30 determines a second relative ratio of the second delivery amount to the first delivery amount based on the adjustment degree, and determines the multiplication value obtained by multiplying the first delivery amount by the second relative ratio as the second delivery amount. The second relative ratio is a relative ratio for determining a second delivery amount larger than the first delivery amount, and when expressed as a fraction, represents a value of 100 or greater. For example, the larger the valve opening degree of the second valve included in the adjustment degree, the more the controller 30 increases the second relative ratio, and the higher the temperature of the braking resistor 21 detected by the second temperature sensor 22, the more the controller 30 increases the second relative ratio.

[0055] When the controller 30 operates as described above, the controller 30 can make the second delivery amount larger than the first delivery amount when the braking resistor 21 operates. As a result, the cooling system S can appropriately cool the FC stack 11 that does not generate power without overcooling, and can appropriately cool the braking resistor 21 in the operating state.

[0056] Even if the cooling system S can cool the FC stack 11 and the braking resistor 21 through the operation of the controller 30 as described above, the second delivery amount can be larger than the first delivery amount. For example, since the FC stack 11 does not generate power when the braking resistor 21 operates, the temperature of the FC stack 11 can decrease and the temperature of the braking resistor 21 can increase, such that the second delivery amount can be larger than the first delivery amount. As a result, in the cooling system S, the cooling water flows back from the second convergence point 6 to the first branch point 4. In contrast, in the cooling system S, a check valve can be provided to prevent the backflow.

[0057] Figure 2 is a diagram schematically showing the configuration of the cooling system S provided with a check valve. Figure 2 The cooling system S shown in Figure 1 is different from the cooling system S shown in Figure 2 in that the cooling system S shown in Figure 2 includes a first check valve 31 and a second check valve 32, and the other parts are the same. As shown in

[0058] By providing the first check valve 31 in this way, even when the second delivery amount is larger than the first delivery amount, the cooling system S can prevent the cooling water from flowing back from the second convergence point 6 to the first branch point 4. In addition, in the cooling system S, since the cooling water flows appropriately to the radiator 10 by preventing the backflow, the FC stack 11 and the braking resistor 21 can be appropriately cooled.

[0059] In addition, as shown in Figure 2As shown, the cooling system S may include a second check valve 32, which is located on the downstream side of the braking resistor 21 in the second branch flow path 3 and on the upstream side of the second confluence point 6 in the second branch flow path 3. By arranging the second check valve 32 in this way, the cooling system S can prevent the cooling water that has passed through the first check valve 31 from flowing back into the second branch flow path 3 when the second delivery volume is much smaller than the first delivery volume.

[0060] The cooling system S may include a three-way valve instead of the first check valve 31 and the second check valve 32. Figure 3 FIG. is a diagram schematically showing the configuration of the cooling system S provided with a three-way valve. Figure 3 The cooling system S shown in Figure 1 differs from the cooling system S shown in

[0061] <Processing sequence of the controller 30>

[0062] Figure 4 FIG. is a diagram showing an example of the processing sequence in the controller 30. Figure 4 The processing sequence shown in Figure 4 is a sequence showing the operation in which the controller 30 outputs the rotational speed of the rotor to the first pump 13 and the second pump 23. The controller 30 repeats

[0063] the processing sequence shown in

[0064] at a predetermined control period (e.g., one second). The controller 30 obtains the adjustment degree of the regulating valve 14 from the regulating valve 14 (S11), and obtains the temperature of the FC stack 11 from the first temperature sensor 12 (S12). The controller 30 determines the first delivery volume of the first pump 13 based on the adjustment degree and the temperature of the FC stack 11 (S13), and outputs the first rotational speed of the rotor corresponding to the first delivery volume to the first pump 13 (S14).

[0065] On the other hand, when the braking resistor 21 is not operating ("No" in S16), the controller 30 determines the second delivery volume of the second pump 23 based on the first delivery volume and the degree of adjustment (S18). The controller 30 outputs the second rotational speed of the rotor corresponding to the determined second delivery volume to the second pump 23 (S19).

[0066] <Example of modification>

[0067] In the above description, the operation has been described in which the controller 30 determines the first delivery volume and the second delivery volume based on parameters such as the degree of adjustment, the temperature of the FC stack 11, and the state of the braking resistor 21, and the parameters such as the degree of adjustment, the temperature of the FC stack 11, and the state of the braking resistor 21 are acquired each time in a predetermined control cycle. However, this is only an example.

[0068] The controller 30 may determine the first delivery volume and the second delivery volume by referring to a delivery volume map stored in the memory of the controller 30. The delivery volume map indicates the degree of adjustment, the state of whether the braking resistor 21 is operating, the first delivery volume corresponding to the temperature of the FC stack 11, and the second delivery volume corresponding to the first delivery volume.

[0069] Figure 5 is a diagram showing an example of the delivery volume map stored in the memory; in Figure 5 For simplicity of description, delivery volume maps M1, M2, and M3 are shown, and the delivery volume maps M1, M2, and M3 represent selections in a plurality of delivery volume maps M for each degree of adjustment of the regulating valve 14. Each delivery volume map M shows the "first delivery volume (or first rotational speed)" and the "second delivery volume (or second rotational speed)" related to the "braking resistor 21", the "FC stack 11 temperature", and the "braking resistor 21 temperature".

[0070] "Braking resistor 21" indicates the state of whether the braking resistor 21 is operating. "FC stack 11 temperature" indicates the range including the temperature detected by the first temperature sensor 12. "Braking resistor 21 temperature" indicates the range including the temperature detected by the second temperature sensor 22. "First delivery volume (or first rotational speed)" is a set value for setting the first rotational speed corresponding to the first delivery volume or the first rotational speed in the first pump 13. "Second delivery volume (or second rotational speed)" is a set value for setting the second rotational speed corresponding to the second delivery volume or the second rotational speed in the second pump 23.

[0071] For example, the controller 30 identifies the delivery amount map M corresponding to the degree of regulation obtained from the regulating valve 14 among the plurality of delivery amount maps M. For example, when the braking resistor 21 operates, the controller 30 identifies the first range in which the temperature detected by the first temperature sensor 12 is included and the second range in which the temperature detected by the second temperature sensor 22 is included. The controller 30 determines the first delivery amount and the second delivery amount by identifying the set value to be set for the first pump 13 corresponding to the identified first range and the set value to be set for the second pump 23 corresponding to the identified second range.

[0072] On the other hand, for example, when the braking resistor 21 does not operate, the controller 30 determines the first delivery amount and the second delivery amount by identifying the first range in which the temperature detected by the first temperature sensor 12 is included, and by identifying the set value to be set for the first pump 13 corresponding to the first range and the set value to be set for the second pump 23. Since the controller 30 operates in this way, the controller 30 can reduce the processing load required to determine the first delivery amount and the second delivery amount.

[0073] In Figure 5 ,"the first delivery amount (or the first rotational speed)" may indicate the first delivery amount or the first rotational speed, and "the second delivery amount (or the second rotational speed)" may indicate the relative ratio with respect to the first delivery amount or the first rotational speed. As an example, assume that "the first delivery amount (or the first rotational speed)" indicates the first rotational speed, and "the second delivery amount (or the second rotational speed)" indicates the relative ratio. In this case, when the braking resistor 21 does not operate, the controller 30 identifies the first rotational speed and the relative ratio corresponding to the identified first range, and determines the multiplication value obtained by multiplying the first rotational speed by the relative ratio as the second rotational speed. Further, in a state where the braking resistor 21 operates, the controller 30 identifies the first rotational speed and the relative ratio corresponding to the identified first range and the second range, and determines the multiplication value obtained by multiplying the first rotational speed by the relative ratio as the second rotational speed.

[0074] <Effect of the cooling system S>

[0075] As described above, the cooling system S includes: a first pump 13 disposed downstream of the radiator 10 and upstream of the FC stack 11 in the cooling flow path 1 and delivering cooling water; a regulating valve 14 disposed at a first confluence point in the cooling flow path 1 and adjusting a first flow rate of the cooling water flowing from the radiator 10 to the first pump 13 and a second flow rate of the cooling water flowing from the first branch flow path 2 to the first pump 13; and a second pump 23 disposed upstream of the braking resistor 21 in the second branch flow path 3 and delivering cooling water; and a controller 30 that determines a first delivery amount of the first pump 13 based on (i) the degree of adjustment of the first flow rate and the second flow rate of the regulating valve 14 and (ii) the temperature of the FC stack 11, and determines a second delivery amount of the second pump 23 based on the degree of adjustment and the first delivery amount.

[0076] Since the cooling system S is configured in this way, the controller 30 can determine the first delivery amount of the first pump 13 for delivering cooling water to the FC stack 11 based on the first flow rate corresponding to the degree of adjustment of the regulating valve 14, so that an appropriate first delivery amount can be determined according to the degree of adjustment. In addition, since the controller 30 can determine a second delivery amount smaller than the first delivery amount based on the degree of adjustment and the first delivery amount, it is possible to prevent the cooling water flowing through the second branch flow path 3 from flowing back at the second confluence point 6. As a result, since the cooling water properly flows through each flow path, the cooling system S achieves proper cooling of the FC stack 11.

[0077] The present disclosure has been described based on the exemplary embodiments. The technical scope of the present disclosure is not limited to the scope described in the above embodiments, and various changes and modifications can be made within the scope of the present disclosure. For example, all or part of the device can be configured with any unit that is functionally or physically dispersed or integrated. In addition, new exemplary embodiments generated by any combination of all or part of the device are included in the exemplary embodiments. In addition, the effects of the new exemplary embodiments brought about by the combination also have the effects of the original exemplary embodiments.

[0078] [Description of Reference Numerals]

[0079] S Cooling system

[0080] 1 Cooling flow path

[0081] 2 First branch flow path

[0082] 3 Second branch flow path

[0083] 4 First branch point

[0084] 5 Second branch point

[0085] 6 Second confluence point

[0086] 10 Radiator

[0087] 11 Fuel cell stack

[0088] 11 FC stack

[0089] 12 First temperature sensor

[0090] 13 First pump

[0091] 14 Control valve

[0092] 21 Braking resistor

[0093] 22 Second temperature sensor

[0094] 23 Second pump

[0095] 30 Controller

[0096] 31 First check valve

[0097] 32 Second check valve

[0098] 33 Three-way valve

Claims

1. A cooling system, comprising: A cooling flow path that circulates cooling water between a radiator and a fuel cell stack; A first pump disposed downstream of the radiator and upstream of the fuel cell stack in the cooling flow path and that conveys the cooling water; A first branch flow path that branches from downstream of the fuel cell stack in the cooling flow path, bypasses the radiator, and converges with the cooling flow path at a first convergence point upstream of the first pump; A regulating valve disposed at the first convergence point in the cooling flow path and that adjusts a first flow rate of the cooling water flowing from the radiator to the first pump and a second flow rate of the cooling water flowing from the first branch flow path to the first pump; A second branch flow path that branches from a branch point upstream of the regulating valve in the cooling flow path and that converges with the cooling flow path at a second convergence point downstream of the fuel cell stack; A braking resistor disposed in the second branch flow path; A second pump disposed upstream of the braking resistor in the second branch flow path and that conveys the cooling water; And A controller that determines a first conveyance amount of the first pump based on (i) an adjustment degree of the first flow rate and the second flow rate of the regulating valve and (ii) a temperature of the fuel cell stack, and that determines a second conveyance amount of the second pump based on the adjustment degree and the first conveyance amount.

2. The cooling system according to claim 1, further comprising: A first check valve disposed downstream of a branch point between the cooling flow path and the first branch flow path in the cooling flow path and upstream of the second convergence point in the cooling flow path.

3. The cooling system according to claim 1 or 2, further comprising: A second check valve disposed downstream of the braking resistor in the second branch flow path and upstream of the second convergence point in the second branch flow path.

4. The cooling system according to claim 1, further comprising: A three-way valve disposed at the second convergence point and that prevents the cooling water from flowing back in the cooling flow path and the second branch flow path.

5. The cooling system according to claim 1, wherein The higher the temperature of the cooling water at the first convergence point, the more the regulating valve increases the first flow rate and decreases the second flow rate.

6. The cooling system according to claim 1, wherein The larger the first flow rate corresponding to the adjustment degree, the more the controller increases the first conveyance amount.

7. The cooling system according to claim 1, wherein The higher the temperature of the fuel cell stack, the more the controller increases the first conveyance amount.

8. The cooling system according to claim 1, wherein The controller determines the second conveyance amount based on the determined first conveyance amount, the adjustment degree, and a temperature of the braking resistor.

9. The cooling system according to claim 8, wherein In a state where the braking resistor is operating, the higher the temperature of the braking resistor, the more the controller increases the second conveyance amount.

10. The cooling system according to claim 8 or 9, wherein when the braking resistor is not operating, the controller determines the second delivery amount to be greater than 0 and less than the first delivery amount.

11. The cooling system according to claim 1, wherein the controller determines the first delivery amount and the second delivery amount by referring to a delivery amount map stored in a memory, the delivery amount map indicating the degree of adjustment, the state of whether the braking resistor is operating, the first delivery amount corresponding to the temperature of the fuel cell stack, and the second delivery amount corresponding to the first delivery amount.

12. The cooling system according to claim 1, wherein when the braking resistor is not operating, after determining the first delivery amount based on the degree of adjustment and the temperature of the fuel cell stack, the controller determines a first relative ratio for determining the second delivery amount that is smaller than the first delivery amount based on the degree of adjustment, and determines a multiplication value obtained by multiplying the first delivery amount by the first relative ratio as the second delivery amount, wherein the first relative ratio is the ratio of the second delivery amount to the first delivery amount.

13. The cooling system according to claim 12, wherein the regulating valve has a first valve for regulating the first flow rate, and the greater the valve opening degree of the first valve, which is included in the degree of adjustment, the more the controller reduces the first relative ratio.

14. The cooling system according to claim 1, wherein when the braking resistor is operating, after determining the first delivery amount based on the degree of adjustment and the temperature of the fuel cell stack, the controller determines a second relative ratio for determining the second delivery amount that is greater than the first delivery amount based on the degree of adjustment, and determines a multiplication value obtained by multiplying the first delivery amount by the second relative ratio as the second delivery amount, wherein the second relative ratio is the ratio of the second delivery amount to the first delivery amount.

15. The cooling system according to claim 14, wherein the regulating valve has a second valve for regulating the second flow rate, and the greater the valve opening degree of the second valve, which is included in the degree of adjustment, the more the controller increases the second relative ratio, and the higher the temperature of the braking resistor, the more the controller increases the second relative ratio.

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