Cooling system and fuel cell vehicle having the same

Abstract

A cooling system that cools a first unit and a second unit is disclosed. The cooling system includes a cooling circuit and a control device. The cooling circuit has a first flow path that supplies a heat medium to the first unit and a second flow path that supplies the heat medium to the second unit. The control device adjusts a first flow rate of the heat medium flowing in the first flow path and a second flow rate of the heat medium flowing in the second flow path based on a first required flow rate required for the first unit and a second required flow rate required for the second unit. When a sum of the first required flow rate and the second required flow rate exceeds a prescribed value, the control device adjusts the first flow rate to a first corrected flow rate that is smaller than the first required flow rate, and limits an amount of operation of the first unit.

Description

Technical Field

[0001] The technology disclosed in this specification relates to cooling systems and fuel cell vehicles equipped with such cooling systems. Background Technology

[0002] A cooling system for cooling a fuel cell unit is disclosed in Japanese Patent Application Publication No. 2014-120386. In this cooling system, abrupt temperature fluctuations of the coolant supplied to the fuel cell unit are suppressed by adjusting the flow rate of the coolant cooled by the radiator.

[0003] Besides fuel cell units, the cooling system described above can also be applied to other heat-generating units. Not limited to fuel cell units, when two heat-generating units are cooled by a shared cooling system, the two units can be arranged side-by-side in a cooling circuit through which a heat transfer medium flows. Thus, the cooling system can supply the required flow rate (hereinafter referred to as the necessary flow rate) of heat transfer medium to each heat-generating unit for cooling. However, a maximum permissible flow rate is specified for the cooling circuit, and the flow of heat transfer medium exceeding this maximum flow rate must be avoided. Therefore, if the sum of the necessary flow rates of the two heat-generating units exceeds the maximum flow rate of the cooling circuit, the two heat-generating units may not be adequately cooled. This specification provides a technique for effectively cooling two heat-generating units using a common cooling system. Summary of the Invention

[0004] This specification discloses a cooling system for cooling a first unit and a second unit. The cooling system includes a cooling circuit and a control device. The cooling circuit has a first flow path for supplying a heat transfer medium to the first unit and a second flow path for supplying the heat transfer medium to the second unit. The control device adjusts the first flow rate of the heat transfer medium flowing in the first flow path and the second flow rate of the heat transfer medium flowing in the second flow path based on a first necessary flow rate required by the first unit and a second necessary flow rate required by the second unit. When the sum of the first necessary flow rate and the second necessary flow rate exceeds a predetermined value, the control device adjusts the first flow rate to a first corrected flow rate smaller than the first necessary flow rate and limits the amount of operation of the first unit.

[0005] In the aforementioned cooling system, when the sum of the first necessary flow rate required by the first unit and the second necessary flow rate required by the second unit exceeds a predetermined value, the first flow rate supplied to the first unit is adjusted to a first corrected flow rate smaller than the first necessary flow rate, and the operation of the first unit is limited. By reducing the first flow rate, it is possible to prevent the overall flow rate of the cooling circuit from becoming excessive, and by limiting the operation of the first unit, it is also possible to suppress the temperature rise of the first unit. Thus, based on the above structure, the first unit and the second unit can be effectively cooled by a shared cooling system. Here, the predetermined value can be, for example, a value equal to the maximum flow rate that the cooling circuit can allow, or a value obtained by subtracting a constant margin from the maximum flow rate. Attached Figure Description

[0006] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein the same reference numerals denote the same elements, wherein,

[0007] Figure 1 The structure of the fuel cell vehicle 10 is shown schematically.

[0008] Figure 2 The structure of the cooling system 30 is schematically shown, and the arrows indicate the flow direction of the cooling water flowing in the cooling circuit 32.

[0009] Figure 3 This is a flowchart illustrating a series of processes performed by ECU20. Detailed Implementation

[0010] In one embodiment of this technology, the first corrected flow rate can also be obtained by subtracting the second necessary flow rate from a predetermined value. Based on this structure, the necessary flow rate of heat medium can be supplied to the second unit, ensuring the cooling performance of the second unit. Therefore, it is particularly effective when the cooling performance of the second unit is given priority compared to the first unit.

[0011] In one embodiment of this technology, when the sum of the first necessary flow rate and the second necessary flow rate is below a predetermined value, the control device may adjust the first flow rate to the first necessary flow rate and the second flow rate to the second necessary flow rate. Based on this structure, the first unit and the second unit can be sufficiently cooled. However, as another embodiment, even when the sum of the first necessary flow rate and the second necessary flow rate is below a predetermined value, at least one of the first flow rate and the second flow rate may be limited according to other purposes and conditions.

[0012] In one embodiment of this technology, the cooling system may also include a radiator installed in the cooling circuit. In this case, when the sum of the first necessary flow rate and the second necessary flow rate exceeds a predetermined value, the control device may increase the heat dissipation generated by the radiator. Based on this structure, the insufficient cooling performance of the two heat-generating units can be compensated not only by limiting the operation of the first unit but also by the heat dissipation generated by the radiator. Thus, the two heat-generating units can be cooled without excessively limiting the operation of the first unit.

[0013] In one embodiment of this technology, a radiator fan may also be provided on the radiator. In this case, in order to increase the heat dissipation generated by the radiator, the control device may also increase the rotational speed of the radiator fan. However, as another embodiment, in order to increase the heat dissipation generated by the radiator, the control device may also increase the flow rate of the heat transfer medium flowing through the radiator.

[0014] In one embodiment of this technology, the first unit can also be a fuel cell unit. In this case, the operating quantity of the first unit can also be the power generation of the fuel cell unit. That is, when the sum of the first necessary flow rate and the second necessary flow rate exceeds a predetermined value, the control device can adjust the first flow rate to a first corrected flow rate smaller than the first necessary flow rate, and limit the power generation of the fuel cell unit. By reducing the heat generated by the fuel cell unit, the temperature rise of the fuel cell unit is suppressed.

[0015] In one embodiment of this technology, the fuel cell unit can also be a power source that supplies electricity to the motor. In this case, the second unit can also be a braking resistor that converts the rotational energy of the motor into heat energy to brake the motor. However, the second unit is not limited to a braking resistor and can also be other types of heat-generating devices.

[0016] In one embodiment of this technology, the fuel cell vehicle may also include a motor that drives the wheels, a fuel cell unit that supplies electricity to the motor, a braking resistor that converts the rotational energy of the motor into heat energy to brake the motor, and a cooling system for any of the above.

[0017] Reference Figure 1 as well as Figure 2 The cooling system 30 of the embodiment and the fuel cell vehicle 10 equipped with the cooling system 30 are described below. Figure 1 as well as Figure 2As shown, in addition to the cooling system 30, the fuel cell vehicle 10 also includes a driving motor 16, a fuel cell unit (hereinafter referred to as FC unit 18), and a braking resistor 22. The cooling system 30 can cool both the FC unit 18 and the braking resistor 22, which are two heat-generating units. Here, the FC unit 18 is an example of the "first unit" disclosed in this specification, and the braking resistor 22 is an example of the "second unit" disclosed in this specification. The "first unit" and "second unit" in this specification are not limited to the combination of the FC unit 18 and the braking resistor 22; other combinations of heat-generating devices may also be used.

[0018] The fuel cell vehicle 10 has multiple wheels 14 and a body 12 supporting the wheels 14. The body 12 is not particularly limited, but is mainly made of metal. The interior of the body 12 is divided into a passenger compartment and a trunk. Each of the multiple wheels 14 is mounted relative to the body 12 and is capable of rotation.

[0019] A driving motor 16, an FC unit 18, and a braking resistor 22 are disposed inside the vehicle body 12. The driving motor 16 drives at least one of the plurality of wheels 14. The driving motor 16 is connected to the FC unit 18 and the braking resistor 22. Here, the driving motor 16 is an example of a "motor" in the technology disclosed in this specification.

[0020] The FC unit 18 includes a fuel cell stack (not shown) consisting of multiple fuel cell units. The fuel cell stack functions as a power source to supply electricity to the driving motor 16. Furthermore, the FC unit 18 includes a power conversion device (not shown), such as a DC-DC converter and / or an inverter. This power conversion device can adjust the power generated by the fuel cell stack and supply it to the driving motor 16.

[0021] Braking resistor 22 is connected between travel motor 16 and FC unit 18. Braking resistor 22 converts the rotational energy of travel motor 16 into heat energy to brake travel motor 16.

[0022] The cooling system 30 includes a cooling circuit 32. An FC unit 18 and a braking resistor 22 are connected in parallel within the cooling circuit 32. Cooling water circulates within the cooling circuit 32. The cooling system 30 can cool the FC unit 18 and the braking resistor 22 through this cooling water circulation. Here, the cooling water is an example of a "heat medium" in the technology disclosed in this specification.

[0023] Cooling circuit 32 has a first flow path 34 and a second flow path 44. The first flow path 34 supplies heat medium to the FC unit 18. A first pump 36 is provided in cooling circuit 32. The first flow rate F1 of the heat medium flowing in the first flow path 34 is regulated by the rotational speed of the first pump 36. The second flow path 44 supplies cooling water to the braking resistor 22. A second pump 46 is provided in cooling circuit 32. The second flow rate F2 of the cooling water flowing in the second flow path 44 is regulated by the rotational speed of the second pump 46. Furthermore, a one-way valve 49 is provided downstream of the braking resistor 22 in the second flow path 44 to prevent backflow of cooling water.

[0024] In the first flow path 34, temperature sensors 38 and 40 are respectively provided between the first pump 36 and the FC unit 18 (i.e., upstream of the FC unit 18) and downstream of the FC unit 18. Each temperature sensor 38 and 40 detects the temperature of the cooling water before and after passing through the FC unit 18. Similarly, in the second flow path 44, temperature sensors 48 and 50 are respectively provided inside the braking resistor 22 and downstream of the braking resistor 22. Each temperature sensor 48 and 50 in the second flow path 44 detects the temperature of the cooling water before and after passing through the braking resistor 22.

[0025] The cooling system 30 includes an ECU (Electronic Control Unit) 20. The ECU 20 is a computer device equipped with a processor and memory. The ECU 20 is located inside the vehicle body 12. The ECU 20 regulates the first flow rate F1 flowing in the first flow path 34 according to the flow rate required by the FC unit 18 (hereinafter referred to as the first necessary flow rate RF1). The ECU 20 regulates the second flow rate F2 flowing in the second flow path 44 according to the flow rate required by the braking resistor 22 (hereinafter referred to as the second necessary flow rate RF2). The ECU 20 is connected to the motor of the first pump 36 and regulates the first flow rate F1 of the first flow path 34 by controlling the first pump 36. The ECU 20 is connected to the motor of the second pump 46 and regulates the second flow rate F2 of the second flow path 44 by controlling the second pump 46. The ECU 20 monitors the temperature sensors 38, 40, 48, and 50 located in the first flow path 34 and the second flow path 44. The ECU 20 can regulate the first flow rate F1 and the second flow rate F2 according to the detection data of each temperature sensor 38, 40, 48, and 50. This suppresses overheating of the FC unit 18 and the braking resistor 22.

[0026] ECU 20 is connected to FC unit 18, and can control the operation of FC unit 18, for example, by limiting the amount of electricity generated. Additionally, ECU 20 is connected to braking resistor 22 via controller 24, and controls the braking action of braking resistor 22. ECU 20 and the components controlled by ECU 20 can be connected via wired or wireless means. However, ECU 20 can also be composed of multiple independent ECUs. In this case, each ECU can also be connected to the drive motor 16, FC unit 18, braking resistor 22, etc.

[0027] The cooling system 30 includes two radiators 52 disposed in a cooling circuit 32. The radiators 52 absorb heat from the coolant flowing in the cooling circuit 32 and dissipate heat to the outside of the vehicle. A temperature sensor 56 for detecting the temperature of the coolant is disposed downstream of the radiators 52 in the cooling circuit 32. The temperature sensor 56 detects the temperature of the coolant discharged from the radiators 52. The ECU 20 is connected to the temperature sensor 56 and monitors the temperature of the coolant flowing in the radiators 52.

[0028] Each radiator 52 is equipped with a radiator fan 54. The radiator fan 54 is rotated by its motor, drawing outside air through the radiator 52. This releases heat from the cooling circuit 32 from the radiator 52 to the outside of the vehicle. The radiator fan 54 is connected to the ECU 20 via a motor. The ECU 20 can adjust the rotational speed of the radiator fan 54. When a temperature rise is detected in the FC unit 18, the radiator fan 54 increases its rotational speed, thereby increasing the heat dissipation of the radiator 52. However, as another embodiment, to increase the heat dissipation generated by the radiator 52, the ECU 20 can also increase the flow rate of coolant flowing through the radiator 52. In this case, the radiator fan 54 is not necessarily required in the radiator 52.

[0029] As an example, two heat sinks 52 are connected in parallel. This allows for efficient cooling of the cooling circuit 32. However, the number of heat sinks 52 is not limited to two; it can also be one or more. As another embodiment, the cooling system 30 may not have heat sinks 52; in this case, other types of heat dissipation devices may be used.

[0030] The cooling system 30 includes two ion removal filters 58 disposed in the cooling circuit 32. The ion removal filters 58 absorb ions from the cooling water flowing in the cooling circuit 32. In the cooling water, ions dissolve from the cooling circuit 32. For the cooling system 30, the absorption of these dissolved ions by the ion removal filters 58 prevents a decrease in the insulation of the vehicle (fuel cell vehicle 10) caused by dissolved ions. The ion removal filters 58 are connected between the radiator 52 and the FC unit 18 and the braking resistor 22. The cooling water flowing through the FC unit 18 and the braking resistor 22 is diverted to the radiator 52 and the ion removal filters 58 via a three-way valve 59. Additionally, as an example, a heat dissipation device 42 is disposed in the first flow path 34 of the cooling circuit 32. The heat dissipation device 42 is connected in parallel with the FC unit 18 in the cooling circuit 32. The heat of the cooling water flowing in the cooling circuit 32 is also dissipated through the heat dissipation device 42.

[0031] As described above, the fuel cell vehicle 10 is configured to cool two parallel-arranged heat-generating units 18 and 22, namely the FC unit 18 and the braking resistor 22, via a shared cooling system 30. Cooling water with its respective necessary flow rates RF1 and RF2 is supplied to each heat-generating unit 18 and 22 for cooling. However, a maximum permissible flow rate Fmax is specified for the cooling circuit 32, and the flow of cooling water exceeding this maximum flow rate Fmax must be avoided. Therefore, if the sum of the necessary flow rates RF1 and RF2 of the two heat-generating units 18 and 22 exceeds the maximum flow rate Fmax of the cooling circuit 32, the two heat-generating units 18 and 22 may not be adequately cooled.

[0032] Therefore, in the cooling system 30 of this embodiment, when the sum of the first necessary flow rate RF1 of the FC unit 18 and the second necessary flow rate RF2 of the braking resistor 22 exceeds a predetermined value, the first flow rate F1 supplied to the FC unit 18 is adjusted to a first corrected flow rate MF1 that is smaller than the first necessary flow rate RF1, and the power generation of the FC unit 18 is limited. By reducing the first flow rate F1, the overall flow rate of the cooling circuit 32 is prevented from becoming too large, and by limiting the operation of the FC unit 18, the temperature rise of the FC unit 18 can also be suppressed. In this way, based on the above structure, the FC unit 18 and the braking resistor 22 can be effectively cooled by the shared cooling system 30. Here, the predetermined value can be, for example, a value equal to the maximum flow rate Fmax that the cooling circuit 32 can allow, or a value obtained by subtracting a constant margin from the maximum flow rate Fmax.

[0033] Reference Figure 3 This describes the processing performed by ECU20. ECU20 executes... Figure 3The series of processes shown is used to cool the FC unit 18 and the braking resistor 22. Furthermore, the specified values ​​here are obtained by subtracting a constant margin from the maximum flow rate Fmax of the cooling circuit 32. However, this series of processes is just one example and does not specifically limit the structure of the ECU 20.

[0034] In step S12, ECU20 determines whether the sum of the first necessary flow rate RF1 of FC unit 18 and the second necessary flow rate RF2 of braking resistor 22 exceeds a predetermined value. If the sum exceeds the predetermined value (yes in S12), the process proceeds to step S14. If the sum is below the predetermined value (no in S12), the process proceeds to step S22.

[0035] In step S14, ECU20 adjusts the second flow rate F2 to the second necessary flow rate RF2, and adjusts the first flow rate F1 to the value obtained by subtracting the second necessary flow rate RF2 from the specified value, which is the first corrected flow rate MF1.

[0036] In step S16, ECU20 limits the power generation of FC unit 18. As a result, the heat generated by FC unit 18 is reduced.

[0037] In step S18, ECU20 determines whether the water temperature of FC unit 18 has risen. Specifically, ECU20 continuously obtains temperature data of the cooling water flowing in FC unit 18 from temperature sensors 38 and 40, and determines whether the cooling water temperature of FC unit 18 has risen based on the obtained temperature data. If the water temperature has risen (Yes in S18), the process proceeds to step S20. If the water temperature has not risen (No in S18), the process ends.

[0038] In step S20, ECU20 increases the speed of radiator fan 54.

[0039] When proceeding from step S12 to step S22, ECU20 adjusts the second flow rate F2 to the second necessary flow rate RF2 and adjusts the first flow rate F1 to the first necessary flow rate RF1.

[0040] If the series of processes in steps S12 to S22 is completed, the process returns to step S12, and ECU20 repeatedly executes the series of processes. As described above, according to Figure 3 The series of processes shown can effectively cool the FC unit 18 and the braking resistor 22 through the shared cooling system 30.

[0041] Furthermore, since the first corrected flow rate MF1 is obtained by subtracting the second necessary flow rate RF2 from the specified value, cooling water at the second necessary flow rate RF2 can be supplied to the braking resistor 22, thereby ensuring the cooling performance of the braking resistor 22. Therefore, this is particularly effective when the cooling performance of the braking resistor 22 is given priority compared to the FC unit 18.

[0042] In the cooling system 30 of this embodiment, when the sum of the first necessary flow rate RF1 and the second necessary flow rate RF2 is below a predetermined value, the ECU 20 adjusts the first flow rate F1 to the first necessary flow rate RF1 and the second flow rate F2 to the second necessary flow rate RF2. Based on this structure, the FC unit 18 and the braking resistor 22 can be sufficiently cooled. As another embodiment, even when the sum of the first necessary flow rate RF1 and the second necessary flow rate RF2 is below a predetermined value, at least one of the first flow rate F1 and the second flow rate F2 can be limited according to other purposes and conditions.

[0043] In the cooling system 30 of this embodiment, when the sum of the first necessary flow rate RF1 and the second necessary flow rate RF2 exceeds a predetermined value, the ECU 20 adjusts the first flow rate R1 to a first corrected flow rate MF1, which is smaller than the first necessary flow rate RF1, and limits the power generation of the FC unit 18. By reducing the heat generation of the FC unit 18, the temperature rise of the FC unit 18 is suppressed.

[0044] In this embodiment, the cooling system 30 is equipped with a radiator 52. When the sum of the first necessary flow rate RF1 and the second necessary flow rate RF2 exceeds a predetermined value, the ECU 20 increases the heat dissipation generated by the radiator 52. Based on this structure, not only can the power generation of the FC unit 18 be limited, but the heat dissipation generated by the radiator 52 can also compensate for the insufficient cooling performance of the two heat-generating units 18 and 22. Thus, the two heat-generating units 18 and 22 can be cooled without excessively limiting the power generation of the FC unit 18. However, the operation limitation of the FC unit 18 is not limited to limiting the power generation; other types of operations that involve heat generation can also be limited.

[0045] The cooling system 30 in this embodiment is not limited to the fuel cell vehicle 10, but can also be mounted on other mobile or stationary devices with two or more heating units.

[0046] The above details specific examples of the technology disclosed in this specification. These are merely illustrative and do not limit the scope of the claims. The technology described within the scope of the claims includes technologies obtained by various modifications and alterations to the specific examples illustrated above. The technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. The technology illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

Claims

1. A cooling system for cooling a first unit and a second unit, wherein, The cooling system includes: A cooling circuit having a first flow path for supplying a heat transfer medium to the first unit and a second flow path for supplying the heat transfer medium to the second unit; and A control device that adjusts the first flow rate of the heat medium flowing in the first flow path and the second flow rate of the heat medium flowing in the second flow path based on the first necessary flow rate required by the first unit and the second necessary flow rate required by the second unit. The control device adjusts the second flow rate to the second necessary flow rate. When the sum of the first necessary flow rate and the second necessary flow rate exceeds a predetermined value, the control device adjusts the first flow rate to a first corrected flow rate that is smaller than the first necessary flow rate, and limits the amount of action of the first unit, wherein... The specified value is either equal to the maximum allowable flow rate of the cooling circuit, or a value obtained by subtracting a constant margin from the maximum flow rate. The first corrected flow rate is the value obtained by subtracting the second necessary flow rate from the specified value.

2. The cooling system according to claim 1, wherein, When the sum of the first necessary flow rate and the second necessary flow rate is below the predetermined value, the control device adjusts the first flow rate to the first necessary flow rate and adjusts the second flow rate to the second necessary flow rate.

3. The cooling system according to claim 1 or 2, wherein, The cooling system also includes a radiator disposed in the cooling circuit. When the sum of the first necessary flow rate and the second necessary flow rate exceeds the specified value, the control device increases the heat dissipation based on the radiator.

4. The cooling system according to claim 3, wherein, A radiator fan is provided on the radiator. In order to increase the heat dissipation based on the radiator, the control device increases the rotational speed of the radiator fan.

5. The cooling system according to claim 1 or 2, wherein, The first unit is a fuel cell unit. The action quantity of the first unit is the power generation of the fuel cell unit.

6. The cooling system according to claim 5, wherein, The fuel cell unit is the power source that supplies electricity to the motor. The second unit is a braking resistor that converts the rotational energy of the motor into heat energy to brake the motor.

7. A fuel cell vehicle, wherein, The fuel cell vehicle has the following features: A motor, which drives the wheels; A fuel cell unit that supplies electricity to the motor; A braking resistor that converts the rotational energy of the motor into heat energy to brake the motor; as well as The cooling system described in claim 6.

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