Fuel cell cooling unit

Abstract

To appropriately control flow rates in two cooling paths in a fuel cell cooling system.SOLUTION: A fuel cell cooling system includes: a first cooling path circulating a first refrigerant for a fuel cell; first flow rate adjustment means provided in the first cooling path to adjust the flow rate in the first cooling path; a radiator; a second cooling path circulating a second refrigerant for the radiator; second flow rate adjustment means provided in the second cooling path to adjust the flow rate in the second cooling path; an intermediate heat exchanger exchanging heat between the first cooling path and the second cooling path; and a controller controlling the first flow rate adjustment means and the second flow rate adjustment means to adjust the flow rate of each of the first cooling path and the second cooling path. The controller determines, after determining a first target value that is a target value of the flow rate in the first cooling path, a second target value that is a target value of the flow rate in the second cooling path, based on the first target value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a cooling system for a fuel cell. [Background technology]

[0002] Cited Document 1 describes a cooling system for a fuel cell. This cooling system includes a first cooling path that circulates a first refrigerant through the fuel cell, a second cooling path that circulates a second refrigerant through a radiator, and an intermediate heat exchanger that exchanges heat between the first cooling path and the second cooling path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-33108 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the cooling system as described above, it is necessary to control the flow rate of both the first cooling path and the second cooling path, and a technique useful for this purpose is needed. [Means for solving the problem]

[0005] The technology disclosed in this specification is embodied in a cooling system for a fuel cell. The cooling system includes a first cooling path for circulating a first coolant through the fuel cell, a first flow rate adjustment means provided in the first cooling path for adjusting the flow rate of the first cooling path, a radiator, a second cooling path for circulating a second coolant through the radiator, a second flow rate adjustment means provided in the second cooling path for adjusting the flow rate of the second cooling path, an intermediate heat exchanger for exchanging heat between the first cooling path and the second cooling path, and a controller for controlling the first flow rate adjustment means and the second flow rate adjustment means to adjust the flow rates of the first cooling path and the second cooling path, and the controller determines a first target value that is a target value of the flow rate of the first cooling path, and then determines a second target value that is a target value of the flow rate of the second cooling path based on the first target value.

[0006] According to the above configuration, the second target value for the flow rate of the second cooling path is determined in consideration of the first target value for the flow rate of the first cooling path, thereby making it possible to appropriately adjust the temperature of the fuel cell by coupling the flow rates of the first and second cooling paths.

[0007] In one embodiment of the present technology, the controller may be capable of executing warm-up control for warming up the fuel cell. In this case, in the warm-up control, a first target value may be determined according to an FC output, which is the output of the fuel cell, and an FC outlet temperature, which is the temperature of the first coolant flowing out from the fuel cell. And, a second target value may be determined according to the first target value, the FC outlet temperature, and a radiator outlet temperature, which is the temperature of the second coolant flowing out from the radiator. With this configuration, in the warm-up operation of the fuel cell, the flow rates of the two cooling paths can be coupled while taking into account the temperature of the coolant in each cooling path.

[0008] In one embodiment of the present technology, the controller may store a first map and a second map for warm-up control. In this case, the first map may describe a first target value according to the FC output and the FC outlet temperature. The second map may describe a second target value according to the first target value, the FC outlet temperature, and the radiator outlet temperature.

[0009] In one embodiment of the present technology, the controller may determine the first target value and the second target value using one or more third maps different from the first map and the second map in normal control after completion of the warm-up control. With this configuration, even in normal operation after the warm-up operation, the flow rates of the two cooling paths can be coupled to appropriately adjust the temperature of the fuel cell.

[0010] In one embodiment of the present technology, in the normal control, when the first target value is Qf and the second target value is Qr, the following formula may be satisfied. Qr≧{(FC outlet temperature - FC inlet temperature) / (Radar inlet temperature - Radiator outlet temperature) x Qf Here, the FC inlet temperature is the temperature of the first coolant flowing into the fuel cell, and the radiator inlet temperature is the temperature of the second coolant flowing into the radiator. In other words, the one or more third maps may describe the first target value and the second target value so that the above formula is satisfied. With this configuration, even during normal operation of the fuel cell, the flow rates of the two cooling paths can be coupled while taking into account the temperature of the coolant in each cooling path. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a cooling system 10 for a fuel cell. [Diagram 2] 4 is a flowchart showing an example of a process executed by the controller 40 to control the flow rate of the refrigerant in the first cooling path 14 and the second cooling path 24. [Diagram 3] 4 is a graph showing the relationship between a first target value and a second target value for each temperature in warm-up control. [Figure 4] 4 is a table showing a relationship between a first target value and a second target value in warm-up control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A fuel cell cooling system 10 according to an embodiment will be described with reference to the drawings. As an example, the cooling system 10 according to the embodiment can be used in a so-called fuel cell electric vehicle (FCEV). The configuration described in the embodiment is not limited to fuel cell electric vehicles, and can be used in other types of devices and equipment that use a fuel cell as a power source.

[0013] 1, a fuel cell cooling system 10 includes a fuel cell 12, a first cooling path 14, a first flow rate adjustment means 16, a plurality of temperature sensors 18a, 18b, 28a, 28b, a radiator 22, a second cooling path 24, a second flow rate adjustment means 26, an intermediate heat exchanger 30, and a controller 40. The fuel cell 12 is supplied with hydrogen from a hydrogen tank (not shown) and with compressed air from a compressor (not shown). The fuel cell 12 generates electric power by reacting hydrogen with oxygen in the compressed air, and the generated electric power is supplied to, for example, a driving motor (not shown) of a fuel cell vehicle.

[0014] The first cooling path 14 is an annular flow path through which the first refrigerant circulates. The first cooling path 14 can circulate the first refrigerant inside the above-mentioned components through a flow path provided inside the fuel cell 12, the first flow rate control means 16, and the intermediate heat exchanger 30. The specific configuration of the first cooling path 14 is not particularly limited. The specific type of the first refrigerant is also not particularly limited, and may be LLC (Long Life Coolant) or other cooling water.

[0015] The first flow rate adjustment means 16 is provided between the intermediate heat exchanger 30 and the fuel cell 12 on the flow path of the first cooling path 14. The first flow rate adjustment means 16 may be, for example, a pump. The first flow rate adjustment means 16 sends out the first refrigerant from an arrangement position in the flow path of the first cooling path 14 toward the intermediate heat exchanger 30. When the first flow rate adjustment means 16 is operated, the first refrigerant flows through the flow path of the first cooling path 14 in the order of the intermediate heat exchanger 30 and the fuel cell 12. That is, the operation of the first flow rate adjustment means 16 transfers heat generated by the fuel cell 12 to the intermediate heat exchanger 30. The specific configuration of the first flow rate adjustment means 16 is not particularly limited.

[0016] The multiple temperature sensors 18a, 18b, 28a, 28b are provided in the first cooling path 14 and the second cooling path 24 to detect the temperature of the first coolant and the temperature of the second coolant. The multiple temperature sensors 18a, 18b, 28a, 28b include a first temperature sensor 18a, a second temperature sensor 18b, a third temperature sensor 28a, and a fourth temperature sensor 28b. The first temperature sensor 18a detects the temperature of the first coolant flowing into the fuel cell 12 (hereinafter referred to as the FC inlet temperature). The second temperature sensor 18b detects the temperature of the first coolant flowing out from the fuel cell 12 (hereinafter referred to as the FC outlet temperature). The third temperature sensor 28a detects the temperature of the second coolant flowing into the radiator 22 (hereinafter referred to as the radiator inlet temperature). The fourth temperature sensor 28b detects the temperature of the second coolant flowing out from the radiator 22 (hereinafter referred to as the radiator outlet temperature). The specific configuration of the temperature sensors 18a, 18b, 28a, and 28b is not particularly limited.

[0017] The radiator 22 is connected to the second cooling path 24, and is a heat radiator that cools the second refrigerant that has passed through the intermediate heat exchanger 30 and been heated. The specific configuration and arrangement of the radiator 22 are not particularly limited. As an example, the radiator 22 in this embodiment is composed of metal fins for heat dissipation and metal pipes through which the second refrigerant flows, and the heat of the second refrigerant circulating inside the radiator 22 is released into the atmosphere by thermal conduction via the metal pipes and the metal fins. The metal fins and metal pipes may be composed of an aluminum alloy or copper, which have excellent thermal conductivity.

[0018] The second cooling path 24 is an annular flow path through which the refrigerant circulates. The second cooling path 24 can circulate the refrigerant inside the above-mentioned components through a flow path provided inside the radiator 22, the second flow rate control means 26, and the intermediate heat exchanger 30. The specific configuration of the second cooling path 24 is not particularly limited. The specific type of the second refrigerant is also not particularly limited, and may be LLC (Long Life Coolant) or other cooling water.

[0019] The second flow rate adjustment means 26 is provided between the intermediate heat exchanger 30 and the radiator 22 on the flow path of the second cooling path 24. The second flow rate adjustment means 26 is, for example, a pump. The second flow rate adjustment means 26 sends out the second refrigerant from an arrangement position in the flow path of the second cooling path 24 toward the intermediate heat exchanger 30. When the second flow rate adjustment means 26 is operated, the second refrigerant flows through the flow path of the second cooling path 24 in the order of the intermediate heat exchanger 30 and the radiator 22. That is, by operating the second flow rate adjustment means 26, the heat transferred from the fuel cell 12 to the intermediate heat exchanger 30 is further transferred to the radiator 22. Note that the specific configuration of the second flow rate adjustment means 26 is not particularly limited.

[0020] The intermediate heat exchanger 30 is disposed between the first cooling path 14 and the second cooling path 24, and exchanges heat between the two cooling paths 14, 24. The specific configuration and arrangement of the intermediate heat exchanger 30 are not particularly limited. As an example, the intermediate heat exchanger 30 in this embodiment is composed of a plurality of metal plates for heat transfer and metal pipes through which the first refrigerant and the second refrigerant circulate, respectively, and transfers heat of the first refrigerant circulating inside the first cooling path 14 to the second refrigerant circulating inside the second cooling path 24 via the metal pipes and the plurality of metal plates. The plurality of metal plates and the metal pipes may be composed of an aluminum alloy or copper, which have excellent thermal conductivity.

[0021] The controller 40 is a device that controls the first flow rate adjustment means 16 and the second flow rate adjustment means 26 to adjust the flow rate of the first refrigerant in the first cooling path 14 and the flow rate of the second refrigerant in the second cooling path 24. The controller 40 is connected to the first flow rate adjustment means 16 and the second flow rate adjustment means 26 by wire or wirelessly. In addition, the controller 40 is also connected to the temperature sensors 18a, 18b, 28a, and 28b by wire or wirelessly, and the temperatures detected by the temperature sensors 18a, 18b, 28a, and 28b are taught to the controller 40.

[0022] The controller 40 prestores a first map and a second map. The first map is used to determine a first target value, which is a target value for the flow rate of the first refrigerant, in warm-up control for warming up the fuel cell 12. The second map is used to determine a second target value, which is a target value for the flow rate of the second refrigerant, in the same warm-up control.

[0023] The first map describes a first target value for the flow rate of the first coolant according to the FC output, which is the output of the fuel cell 12, and the FC outlet temperature. The second map describes a second target value for the flow rate of the second coolant according to the first target value, the FC outlet temperature, and the radiator outlet temperature. As a result, in the warm-up control, the first target value is determined according to, for example, the FC output taught by another controller, and the temperature detected by the second temperature sensor 18b (i.e., the FC outlet temperature). Then, after the first target value is determined, the second target value is determined according to the first target value, the temperature detected by the second temperature sensor 18b (i.e., the FC outlet temperature), and the temperature detected by the fourth temperature sensor 28b (i.e., the radiator outlet temperature).

[0024] In this way, the controller 40 of this embodiment determines a first target value, which is a target value of the flow rate of the first cooling path 14, during warm-up operation for warming up the fuel cell, and then determines a second target value, which is a target value of the flow rate of the second cooling path 24, based on the first target value. With this configuration, the second target value for the flow rate of the second cooling path 24 is determined in a form that takes into account the first target value for the flow rate of the first cooling path 14. That is, by coupling the flow rate of the first cooling path 14 and the flow rate of the second cooling path 24, the temperature of the fuel cell 12 can be appropriately adjusted. In addition, the first target value and the second target value are determined taking into account the FC output and the temperature of each refrigerant in each cooling path 14, 24. As a result, the flow rates of the two cooling paths 14, 24 are appropriately coupled depending on the state of the fuel cell 12 and its environment, and the temperature of the fuel cell 12 is appropriately adjusted.

[0025] The control process executed by the controller 40 will be described with reference to Fig. 2. The controller 40 repeatedly executes a series of control procedures shown in Fig. 2, for example, when the fuel cell vehicle is powered on and the fuel cell 12 starts generating electricity. First, the controller 40 acquires the temperature of the first refrigerant circulating in the first cooling path 14. More specifically, the controller 40 acquires the FC outlet temperature from the second temperature sensor 18b. Then, the controller 40 determines whether the acquired FC outlet temperature is equal to or higher than a predetermined warm-up end temperature Tg (S10). The warm-up end temperature Tg may be any value, and may be, for example, a temperature within a range of 30°C to 60°C.

[0026] If the FC outlet temperature is equal to or higher than the warm-up end temperature Tg (S10: Yes), the controller 40 performs normal control (S12). The normal control will be described in detail later. On the other hand, if the FC outlet temperature is lower than the warm-up end temperature Tg (S10: No), the controller 40 performs warm-up control (S20).

[0027] In the warm-up control, the controller 40 judges whether the FC outlet temperature is 0°C or less (S22). The judgment value "0°C" used in this step S22 is not limited to this, and any value can be adopted. If the FC outlet temperature is 0°C or less (S22: Yes), the controller 40 uses the first map and the second map corresponding to the FC outlet temperature to determine the first target value (Qf) for the flow rate of the first cooling path 14 and the second target value (Qr) for the flow rate of the second cooling path 24 (S24). As an example, in the first map and the second map used in this step S24, the first target value (Qf) and the second target value (Qr) are determined so that the relationship shown in column A of FIG. 4 is satisfied. Then, the controller 40 controls the first flow rate adjustment means 16 and the second flow rate adjustment means 26 based on the determined first target value (Qf) and second target value (Qr). If the power supply of the fuel cell vehicle is not turned off (S30: No), the controller 40 returns to the initial process of step S10.

[0028] On the other hand, when the FC outlet temperature exceeds 0°C (S22: No), the controller 40 further judges whether the FC outlet temperature is less than the warm-up end temperature Tg (S26). When the FC outlet temperature exceeds 0°C and is less than the warm-up end temperature Tg (S26: Yes), the controller 40 uses the first map and the second map according to the FC outlet temperature to determine the first target value (Qf) for the flow rate of the first cooling path 14 and the second target value (Qr) for the flow rate of the second cooling path 24 (S28). As an example, in the first map and the second map used in this step S28, the first target value (Qf) and the second target value (Qr) are determined so that the relationship shown in column B of FIG. 4 is satisfied. Then, the controller 40 controls the first flow rate adjustment means 16 and the second flow rate adjustment means 26 based on the determined first target value (Qf) and second target value (Qr). If the power supply of the fuel cell vehicle is not turned off (S30: No), the controller 40 returns to the initial process of step S10.

[0029] On the other hand, if the FC outlet temperature is equal to or higher than the warm-up end temperature Tg (S26: No), the controller 40 ends the warm-up control and returns to the initial process of step S10.

[0030] As described above, the warm-up control by the controller 40 starts when the FC outlet temperature is lower than the warm-up end temperature Tg, and ends when the FC outlet temperature becomes equal to or higher than the warm-up end temperature Tg. During this time, the first target value (Qf) and the second target value (Qr) are determined so as to be coupled, and are adjusted so as to change in correlation with each other, for example, as shown in FIG.

[0031] Returning to the flow of FIG. 2, the normal control (S12) will be described. In the normal control (S12), the controller 40 determines the first target value (Qf) and the second target value (Qr) using one or more third maps different from the first map and the second map described above (S14). That is, a map different from the warm-up control is used. The specific configuration of the third map is not particularly limited. As an example, in the third map of this embodiment, the first target value (Qf) and the second target value (Qr) are determined to satisfy the following relational expression. Qr≧{(FC outlet temperature - FC inlet temperature) / (Radio inlet temperature - Radiator outlet temperature)}×Qf With this configuration, even during normal operation of the fuel cell 12, the flow rates of the two cooling paths 14, 24 can be coupled while taking into consideration the temperature of the coolant in each of the cooling paths 14, 24.

[0032] 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 changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility. [Explanation of symbols]

[0033] 10: Cooling system for fuel cell, 12: Fuel cell, 14: First cooling path, 16: First flow rate adjustment means, 22: Radiator, 24: Second cooling path, 26: Second flow rate adjustment means, 30: Intermediate heat exchanger, 40: Controller

Claims

1. A cooling system for a fuel cell, comprising: a first cooling path for circulating a first coolant through the fuel cell; a first flow rate adjusting means provided in the first cooling path and configured to adjust a flow rate of the first cooling path; A radiator, a second cooling path for circulating a second coolant through the radiator; a second flow rate adjusting means provided in the second cooling path and configured to adjust a flow rate of the second cooling path; an intermediate heat exchanger that exchanges heat between the first cooling path and the second cooling path; a controller that controls the first flow rate adjustment means and the second flow rate adjustment means to adjust the flow rates of the first cooling path and the second cooling path; Equipped with the controller determines a first target value that is a target value of the flow rate of the first cooling path, and then determines a second target value that is a target value of the flow rate of the second cooling path based on the first target value. Cooling system.

2. the controller is capable of executing warm-up control for warming up the fuel cell; In the warm-up control, the first target value is determined according to an FC output, which is an output of the fuel cell, and an FC outlet temperature, which is a temperature of the first coolant flowing out from the fuel cell; the second target value is determined in accordance with the first target value, the FC outlet temperature, and a radiator outlet temperature which is the temperature of the second coolant flowing out from the radiator. The cooling system of claim 1 .

3. the controller stores a first map and a second map for the warm-up control, the first map describes the first target value according to the FC output and the FC outlet temperature, 3. The cooling system according to claim 2, wherein the second map describes the second target value in accordance with the first target value, the FC outlet temperature, and the radiator outlet temperature.

4. The cooling system according to claim 3, wherein, in normal control after completion of the warm-up control, the controller determines the first target value and the second target value using one or more third maps different from the first map and the second map.

5. In the normal control, when the first target value is set to Qf and the second target value is set to Qr, Qr≧{(FC outlet temperature - FC inlet temperature) / (radio inlet temperature - radio outlet temperature) × Qf, 5. The cooling system according to claim 4, wherein the FC inlet temperature is a temperature of the first coolant flowing into the fuel cell, and the radiator inlet temperature is a temperature of the second coolant flowing into the radiator.

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