Method for controlling cooling system and cooling system

Abstract

Provided is a method for controlling a cooling system comprising: a first circuit that is a closed circuit in which cooling water flows and in which a first component to be cooled and a first water pump that circulates the cooling water are disposed; a second circuit that is a closed circuit in which cooling water flows and in which a second component to be cooled and a second water pump that circulates the cooling water are disposed; a connection circuit connected to the first circuit and the second circuit; a switching mechanism capable of connecting and disconnecting the first circuit and the second circuit; a cooling mechanism that cools the cooling water flowing through the first circuit and the second circuit; and an air discharge mechanism provided in one of the first circuit and the second circuit. In this control method, air contained in the cooling water in the first circuit is discharged to the outside of the cooling system via the air discharge mechanism. Furthermore, when the cooling water is injected, the switching mechanism is switched so as to alternately execute connected circulation in which the cooling water is circulated through the mutually connecte first circuit and second circuit and closed-circuit circulation in which the cooling water is circulated through the mutually separated first circuit and second circuit.

Description

Cooling system control method and cooling system

[0001] The present invention relates to a cooling system control method and a cooling system.

[0002] In a cooling system, if the water injection rate in the circuit through which the coolant flows is low, problems such as reduced cooling performance and louder running water noise can occur. Furthermore, while the water pump is controlled by the driving force against the resistance of the water, if there is a lot of low-resistance air in the circuit, the water pump may over-speed and be shut down as a fail-safe measure. Repeated shut-down measures could result in the water pump breaking down. Therefore, cooling systems typically manage the ratio of coolant in the circuit (water injection rate).

[0003] However, the water injection rate of the circuit is determined by the degree of vacuum or negative pressure that can be created, so whether a sufficient water injection rate can be achieved depends on the performance of the equipment. For example, when a cooling system is repaired and reassembled at a dealer, some dealers may not have the equipment to obtain a sufficient water injection rate.

[0004] JP3104743B2 discloses a coolant replacement method in which new coolant is pressurized and supplied from one part of the coolant circulation mechanism, and the old coolant is sucked from another part of the coolant circulation mechanism and discharged, thereby replacing the old coolant with new coolant.

[0005] Even in the coolant replacement method described in JP3104743B2, the water injection rate of the circuit after replacement with new coolant is determined by the degree of vacuum, or negative pressure, that can be created, and therefore depends on the performance of the equipment. Therefore, for example, if a dealer does not have sufficient equipment, there is a risk that the cooling system after repair will not achieve the target water injection rate. Another problem is that preparing high-performance equipment increases costs.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a cooling system and a control method for a cooling system that can obtain a high water injection rate in a simple manner.

[0007] According to one aspect of the present invention, there is provided a control method for a cooling system including: a first circuit, a closed circuit through which coolant flows, the first circuit including a first component to be cooled and a first water pump for circulating the coolant; a second circuit, a closed circuit through which coolant flows, the second circuit including a second component to be cooled and a second water pump for circulating the coolant; a connecting circuit connecting the first circuit and the second circuit; a switching mechanism for connecting or disconnecting the first circuit and the second circuit; a cooling mechanism for cooling the coolant flowing through the first circuit and the second circuit; and an air exhaust mechanism provided in either the first circuit or the second circuit. In this control method, air contained in the coolant in the first circuit is exhausted to the outside of the cooling system via the air exhaust mechanism. Furthermore, during coolant injection, the switching mechanism is switched to alternately perform a connected circulation in which the first circuit and the second circuit are connected to circulate the coolant and a closed-circuit circulation in which the first circuit and the second circuit are disconnected to circulate the coolant.

[0008] FIG. 1 is a schematic diagram of a cooling system to which a control method according to an embodiment of the present invention is applied. FIG. 2 is a schematic diagram of a first valve. FIG. 3 is a diagram showing a first circuit pattern. FIG. 4 is a diagram showing the state of the first valve in the first pattern. FIG. 5 is a diagram showing a second circuit pattern. FIG. 6 is a diagram showing the state of the first valve in the second pattern. FIG. 7 is a diagram showing a third circuit pattern. FIG. 8 is a diagram showing the state of the first valve in the third pattern. FIG. 9 is a diagram showing a fourth circuit pattern. FIG. 10 is a diagram showing the state of the first valve in the fourth pattern. FIG. 11 is a flowchart illustrating water injection control according to an embodiment of the present invention.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] 1 is a schematic diagram of a cooling system 100 to which a control method according to an embodiment of the present invention is applied. The cooling system 100 is mounted on, for example, an electric vehicle. Note that the electric vehicle referred to here includes not only a battery electric vehicle (BEV) but also a hybrid electric vehicle (HEV) and the like.

[0011] 1 , the cooling system 100 includes a first circuit C1 that is a closed circuit through which coolant flows, a second circuit C2 that is also a closed circuit through which coolant flows, a connecting circuit 30 that connects the first circuit C1 and the second circuit C2, a switching mechanism 40 that can connect or disconnect the first circuit C1 and the second circuit C2, and a controller 50 that serves as a control unit. Note that, hereinafter, the first circuit C1, the second circuit C2, and the connecting circuit 30 will be collectively referred to as the circuits of the cooling system 100, or simply as the circuits.

[0012] The first circuit C1 is a closed circuit through which coolant flows, and includes a first water pump 11 for circulating the coolant, an electric powertrain (ePT) 12 as a first component to be cooled, and a radiator 13 as a cooling mechanism, arranged in series in this order. The first circuit C1 also includes a reserve tank 14 connected to the radiator 13.

[0013] The ePT 12 includes high-voltage components such as a charger, a DC-DC converter, an inverter, and a traction motor. The circuit on the outlet side of the ePT 12 is equipped with a temperature sensor (not shown) that detects the temperature of the ePT 12. The detected temperature of the ePT 12 is transmitted to the controller 50 (described later).

[0014] The radiator 13 is a cooling mechanism that exchanges heat between the coolant flowing inside the first circuit C1 and the atmosphere, and is disposed downstream of the ePT 12. The radiator 13 is also connected to a reserve tank 14.

[0015] A reserve tank 14 connected to the radiator 13 stores coolant to be used to replenish the circuits of the cooling system 100. The reserve tank 14 traps air contained in the coolant in the circuits of the cooling system 100 and discharges it to the outside of the cooling system 100. In other words, the reserve tank 14 functions as both a water replenishment mechanism and an air discharge mechanism. The reserve tank 14 is provided with a water flow control valve (not shown), the operation of which is controlled by a controller 50 (described later). The controller 50 controls the water flow control valve to replenish the circuits of the cooling system 100 as needed. To prevent air from entering the reserve tank 14 from the outside, the reserve tank 14 is opened by applying positive pressure when air is discharged from the reserve tank 14 to the outside.

[0016] The second circuit C2 is a closed circuit through which coolant flows, and in the second circuit C2, a second water pump 21 that circulates the coolant, a battery 22 as the second component to be cooled, and a chiller 23 that functions as a heat source for heating the passenger compartment are arranged in series in this order.

[0017] The battery 22 supplies driving power to the traction motor of the ePT 12. The circuit on the outlet side of the battery 22 is equipped with a temperature sensor (not shown) that detects the temperature of the battery 22. The detected temperature of the battery 22 is sent to the controller 50, which will be described later.

[0018] The chiller (heat exchanger) 23 is configured to be able to exchange heat between the heat of the cooling water flowing through the second circuit C2 and the heat medium (also referred to as air conditioning heat medium) of the air conditioning cycle AC.

[0019] The air conditioning cycle AC includes a chiller 23, a compressor 60, a condenser 61, and an expander 62. The high-pressure side pipe runs from the compressor 60 via the condenser 61 to the expander 62, and the low-pressure side pipe runs from the expander 62 via the chiller 23 to the compressor 60.

[0020] The compressor 60 is disposed in, for example, a motor room, and compresses the heat medium to produce a high-temperature, high-pressure gas, which is then supplied to the condenser 61 .

[0021] The condenser 61 is disposed in the vehicle interior air conditioning duct at a position where the air from the blower hits the condenser 61, and exchanges heat between the heat medium supplied by the compressor 60 and the cool air from the blower. That is, the air that has passed through the blower is heated by heat exchange in the condenser 61 and supplied to the vehicle interior as warm air for heating.

[0022] The expander 62 is disposed in, for example, a motor room, and reduces the pressure of the heat medium that has passed through the condenser 61 before it flows into the chiller 23, thereby converting it into a low-temperature, low-pressure, gas-liquid two-phase state.

[0023] The chiller 23 exchanges heat between the heat medium in the low-temperature, low-pressure, gas-liquid two-phase state and the heat of the coolant flowing through the second circuit C2. That is, the chiller 23 pumps up the heat that is wasted from the battery 22 and the like into the coolant.

[0024] As described above, the heat pumped up by the chiller 23 is dissipated by the condenser 61 .

[0025] The connecting circuit 30 is a circuit that connects the first circuit C1 and the second circuit C2. Specifically, the connecting circuit 30 connects the first circuit C1 between the radiator 13 and the first water pump 11 and the second circuit C2 between the chiller 23 and the second water pump 21. When the connecting circuit 30 is opened by a switching mechanism 40 (described later), the coolant flowing through the first circuit C1 or the second circuit C2 flows into the connecting circuit 30.

[0026] The switching mechanism 40 is configured to be able to connect or disconnect the first circuit C1 and the second circuit C2. In this embodiment, the switching mechanism 40 includes a first valve 41, a second valve 42, and a third valve 43.

[0027] The first valve 41 is a four-way valve disposed across the first circuit C1 downstream of the ePT 12 (between the ePT 12 and the radiator 13) and the second circuit C2 downstream of the battery 22 (between the battery 22 and the chiller 23). The first valve 41 controls the destinations of the coolant downstream of the ePT 12 and the coolant downstream of the battery 22, and together with the second valve 42 and the third valve 43, determines the pattern of the circuit through which the coolant flows in the cooling system 100. Details of the pattern of the circuit through which the coolant flows will be described later. The operation of the first valve 41 is controlled by the controller 50, which will be described later.

[0028] 2 is a schematic diagram of the first valve 41. As shown in FIG. 2, the first valve 41 includes a first flow path 41A connected to the second circuit C2 upstream of the chiller 23, a second flow path 41B connected to the second circuit C2 downstream of the battery 22, a third flow path 41C connected to the first circuit C1 downstream of the ePT 12, and a fourth flow path 41D connected to the first circuit C1 upstream of the radiator 13. The first valve 41 also includes a switching valve 410 that opens and closes each of the flow paths 41A to 41D and switches the connection destinations of the second flow path 41B and the third flow path 41C. The first valve 41 switches the circuit pattern through which the coolant flows by opening and closing each of the flow paths 41A to 41D and switching the connection destinations of the second flow path 41B and the third flow path 41C.

[0029] The second valve 42 is a three-way valve provided at a position where the first circuit C1 and the connecting circuit 30 are connected, and is configured to be able to connect or disconnect the first circuit C1 and the connecting circuit 30. The second valve 42, together with the first valve 41 and the third valve 43, determines the circuit pattern through which the coolant flows in the cooling system 100 by switching between connecting and disconnecting the first circuit C1 and the connecting circuit 30.

[0030] The third valve 43 is a three-way valve provided at a position where the second circuit C2 and the connecting circuit 30 are connected, and is configured to be able to connect or disconnect the second circuit C2 from the connecting circuit 30. The third valve 43, together with the first valve 41 and the second valve 42, determines the circuit pattern through which the coolant flows in the cooling system 100 by switching between connecting and disconnecting the second circuit C2 from the connecting circuit 30.

[0031] The controller 50 is configured by a computer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface) and is programmed to be able to execute the processes described below. Note that the controller 50 can also be configured by multiple computer hardware that executes the processes in a distributed manner.

[0032] The controller 50 controls the operation of the switching mechanism 40. Specifically, the controller 50 controls the operation of the first valve 41, the second valve 42, and the third valve 43 to execute each process by switching the pattern of the circuit through which the cooling water flows in the cooling system 100. For example, the controller 50 executes water injection control and thermal recovery control, which will be described later, by switching the circuit pattern.

[0033] Next, a description will be given of the circuit patterns through which the coolant flows in the cooling system 100. The controller 50 uses the following circuit patterns depending on the temperatures of the ePT 12 and the battery 22, etc. (thermal recovery control).

[0034] [First Pattern] FIG. 3 is a diagram showing the first pattern of the circuit.

[0035] In the figure, bold lines with arrows indicate the paths along which the coolant flows, and the arrows indicate the direction of the flow. This also applies to Figures 5, 7, and 9, which will be described later. Note that the air conditioning cycle AC is omitted in Figures 3, 5, 7, and 9.

[0036] The first pattern is a circuit pattern that performs a connected circulation system in which the first circuit C1 and the second circuit C2 are connected to circulate the coolant. In the first pattern, as shown in FIG. 4 , the first valve 41 is controlled so that the second flow path 41B, which connects to the second circuit C2 downstream of the battery 22, and the third flow path 41C, which connects to the first circuit C1 downstream of the ePT 12, are connected to the fourth flow path 41D, which connects to the first circuit C1 upstream of the radiator 13. Meanwhile, the first flow path 41A, which connects to the second circuit C2 upstream of the chiller 23, is controlled to a closed state. The second valve 42 is controlled so that the coolant flowing in from the first circuit C1 downstream of the radiator 13 flows out to the first circuit C1 upstream of the ePT 12 and the connecting circuit 30. The third valve 43 is controlled so that the coolant flowing in from the first circuit C1 via the connecting circuit 30 flows out to the second circuit C2 upstream of the second water pump 21.

[0037] Therefore, the coolant flow in the first pattern is as follows: The coolant that has passed through the battery 22 and the ePT 12 flows into the first circuit C1 upstream of the radiator 13 via the first valve 41. The coolant that has flowed into the first circuit C1 passes through the radiator 13, with some of it circulating through the first circuit C1 as is, and the other part flows into the second circuit C2 via the second valve 42 and the connecting circuit 30. The coolant that has flowed into the second circuit C2 then passes through the battery 22 and flows back into the first valve 41.

[0038] In this way, in the first pattern, the coolant that has passed through the battery 22 and the coolant that has passed through the ePT 12 both pass through the radiator 13, which is a cooling mechanism, and therefore the heat from the battery 22 and the ePT 12 that is wasted into the coolant does not flow to the chiller 23. In other words, the first pattern is a circuit pattern for cooling the battery 22 and the ePT 12 by the radiator 13.

[0039] [Second Pattern] FIG. 5 is a diagram showing a second pattern of the circuit.

[0040] The second pattern is a circuit pattern that performs closed circuit circulation, in which the coolant is circulated while being separated from the first circuit C1 and the second circuit C2, and that recovers waste heat from the battery 22. In the second pattern, the first valve 41 is controlled, as shown in FIG. 6 , to connect the first flow path 41A to the second flow path 41B and to connect the third flow path 41C to the fourth flow path 41D. The second valve 42 is controlled to allow the coolant flowing in from downstream of the radiator 13 in the first circuit C1 to flow only into the first circuit C1 upstream of the ePT 12, and not to flow into the connecting circuit 30. The third valve 43 is controlled to allow the coolant flowing in from downstream of the chiller 23 to flow only into the second circuit C2 upstream of the second water pump 21, and not to flow into the connecting circuit 30. As described above, by controlling the switching mechanism 40 (first valve 41, second valve 42, third valve 43), the first circuit C1 and the second circuit C2 become independent closed circuits, and the cooling water circulates independently through the first circuit C1 and the second circuit C2.

[0041] In the second pattern, in the second circuit C2, the coolant that has passed through the battery 22 passes through the chiller 23. Therefore, the heat of the battery 22 that is wasted into the coolant is heat exchanged in the chiller 23. This allows the heat of the battery 22 to be recovered and used for heating. On the other hand, the coolant that has passed through the ePT 12 does not pass through the chiller 23, and therefore the heat of the ePT 12 is not used for heating.

[0042] [Third Pattern] FIG. 7 is a diagram showing a third pattern of the circuit.

[0043] The third pattern is a circuit pattern that connects the first circuit C1 and the second circuit C2 and recovers waste heat from the ePT 12. In the third pattern, as shown in FIG. 8 , the first valve 41 connects the first flow path 41A and the third flow path 41C, and the second flow path 41B and the fourth flow path 41D are controlled to be closed. The third valve 43 is controlled so that the coolant flowing in from downstream of the chiller 23 flows only into the connecting circuit 30 and does not flow into the second circuit C2 upstream of the second water pump 21. The second valve 42 is controlled so that the coolant flowing in from the second circuit C2 via the connecting circuit 30 flows only into the first circuit C1 upstream of the ePT 12.

[0044] Therefore, the cooling water flow in the third pattern is as follows: The cooling water that passes through the ePT 12 in the first circuit C1 flows into the second circuit C2 via the first valve 41. The cooling water that flows into the second circuit C2 passes through the chiller 23 and returns to the first circuit C1 via the third valve 43, the connecting circuit 30, and the second valve 42.

[0045] In the third pattern, in the first circuit C1, the coolant that has passed through the ePT 12 flows into the second circuit C2 and passes through the chiller 23. Therefore, the heat from the ePT 12 that is wasted into the coolant is heat exchanged in the chiller 23. This allows the heat from the ePT 12 to be recovered and used for heating. On the other hand, the coolant that has passed through the battery 22 does not pass through the chiller 23, so the heat from the ePT 12 is not used for heating.

[0046] [Fourth Pattern] FIG. 9 is a diagram showing a fourth pattern of the circuit.

[0047] The fourth pattern is a circuit pattern that connects the first circuit C1 and the second circuit C2 and recovers waste heat from the ePT 12 and the battery 22. In the fourth pattern, as shown in FIG. 10 , the first valve 41 is controlled so that the second flow path 41B and the third flow path 41C are connected to the first flow path 41A, and the fourth flow path 41D is closed. The third valve 43 is controlled so that the coolant flowing in from downstream of the chiller 23 flows to both the second water pump 21 and the connecting circuit 30. The second valve 42 is controlled so that the coolant flowing in from the second circuit C2 via the connecting circuit 30 flows only to the first circuit C1 upstream of the ePT 12.

[0048] Therefore, the cooling water flow in the fourth pattern is as follows: The cooling water that passes through the ePT 12 in the first circuit C1 flows into the second circuit C2 via the first valve 41. The cooling water that flows into the second circuit C2 passes through the chiller 23, and the cooling water that passes through the chiller 23 branches at the third valve 43; one branch flows directly through the second circuit C2, and the other branch returns to the first circuit C1 via the connecting circuit 30 and the second valve 42.

[0049] In the fourth pattern, in the first circuit C1, the coolant that has passed through the ePT 12 flows into the second circuit C2 and passes through the chiller 23. In the second circuit C2, the coolant that has passed through the battery 22 also passes through the chiller 23. Therefore, the heat from both the ePT 12 and the battery 22 that is wasted into the coolant is exchanged in the chiller 23. This allows the heat from the ePT 12 and the battery 22 to be recovered and used for heating.

[0050] As described above, the cooling system 100 appropriately controls the switching mechanism 40 to switch the circuit pattern based on the temperatures of the ePT 12 and the battery 22, etc.

[0051] In a cooling system, if the water injection rate in the circuit through which the coolant flows is low, problems such as reduced cooling performance and louder running water noise can occur. Furthermore, the water pump is controlled by the driving force against the resistance of the water. However, if there is a large amount of air with low resistance in the circuit, the water pump may over-speed and be shut down as a fail-safe measure. Repeated shut-down measures could result in the water pump breaking down. Therefore, cooling systems typically manage the water injection rate in the circuit.

[0052] However, the water injection rate of a circuit is determined by the degree of vacuum, or negative pressure, that can be created, so whether a sufficient water injection rate can be achieved depends on the performance of the equipment. In particular, in areas where components such as batteries are located, the circuit through which the cooling water flows meanders in a complex manner, making it easy for air to accumulate at the curves. Therefore, high-performance equipment is required to improve the water injection rate. For example, when a dealer repairs and reassembles a cooling system, some dealers may not be able to provide equipment that can achieve a sufficient water injection rate. Another problem is that providing high-performance equipment increases costs.

[0053] Therefore, in this embodiment, when injecting coolant into the circuits, such as when reassembling the cooling system 100, a water injection control is executed that alternates between a connected circulation in which the first circuit C1, which is a closed circuit through which the coolant flows, and a closed circuit circulation in which the first circuit C1 and the second circuit C2, which is a closed circuit through which the coolant flows, are connected and circulates the coolant, and a closed circuit circulation in which the first circuit C1 and the second circuit C2 are separated and the coolant is circulated. Air contained in the coolant in the first circuit C1 and the second circuit C2 is discharged to the outside of the cooling system 100 via a reserve tank (air discharge mechanism) 14 provided in the first circuit C1. In this way, the connected circulation and the closed circuit circulation are alternately performed to circulate the coolant in the circuits, so that air remaining in each circuit (the first circuit C1 and the second circuit C2) can be efficiently discharged to the outside of the system (outside the vehicle). Furthermore, because the interlocked circulation and closed circuit circulation can be performed by switching the switching mechanism 40, which can connect and disconnect the first circuit C1 and the second circuit C2, a high water injection rate can be obtained without introducing high-performance equipment. In other words, a high water injection rate can be obtained in a simple manner, and the system can be made inexpensive.

[0054] If a reserve tank were provided for each of the first and second circuits C1 and C2 to efficiently discharge the air contained in the coolant from the first and second circuits C1 and C2, pressure loss would occur due to components between the two reserve tanks, creating a pressure difference that could cause the water from the higher-pressure reserve tank to flow into the lower-pressure reserve tank, potentially resulting in water spraying. On the other hand, if only one reserve tank were used, the efficiency of air discharge would decrease, resulting in poor water injection performance. However, in this embodiment, by alternating between connected circulation and closed-circuit circulation, water injection performance can be improved even with only one reserve tank. In other words, a high water injection rate can be achieved without introducing high-performance equipment or increasing the number of reserve tanks, thereby reducing the cost of the system.

[0055] The water injection control will be described in detail below.

[0056] 11 is a flowchart illustrating the water injection control. The following controls are all executed by the controller 50. The controller 50 also replenishes water from the reserve tank 14 to the circuit of the cooling system 100 as needed.

[0057] When a control command to start water injection control is received at a dealer or the like after the cooling system 100 has been repaired and is being reassembled, the controller 50 starts the water injection control. For example, after the cooling system 100 has been repaired, if a control command to start water injection control is sent from the fault diagnosis device to the controller 50 while the vehicle is connected to the fault diagnosis device, the controller 50 starts the water injection control, and water injection into the circuit of the cooling system 100 begins.

[0058] In step S10, the controller 50 executes a connected circulation mode, connecting the first circuit C1 and the second circuit C2 to circulate the coolant. Specifically, the controller 50 controls the switching mechanism 40 so that the cooling system 100 is in the first pattern ( FIG. 3 ). In the first pattern, both the coolant that has passed through the ePT 12 and the battery 22 pass through the radiator 13. This causes air accumulated near the ePT 12 and the battery 22 to be discharged from the reserve tank 14 connected to the radiator 13 to the outside of the cooling system 100. In the first pattern, the coolant that has passed through the first valve 41, the second valve 42, and the third valve 43 also passes through the radiator 13. This causes air accumulated near each valve to be discharged from the reserve tank 14 to the outside of the cooling system 100. By executing the connected circulation mode in this manner, the coolant injection rate increases. The connected circulation mode is executed, for example, until the gas-liquid exchange reaches equilibrium (the coolant injection rate approaches equilibrium). After the connection circulation has been performed for a certain period of time, the controller 50 executes the process of step S20.

[0059] In step S20, the controller 50 separates the first circuit C1 from the second circuit C2 and performs closed-circuit circulation, circulating the coolant. Specifically, the controller 50 controls the switching mechanism 40 so that the cooling system 100 is in the second pattern ( FIG. 5 ). In the second pattern, the coolant circulating through the second circuit C2 passes through the chiller 23. This causes air accumulating near the chiller 23 to circulate through the second circuit C2. Furthermore, because the coolant circulating through the second circuit C2 passes through the battery 22, air accumulating near the battery 22 that was not completely discharged in step S10 also circulates through the second circuit C2. Furthermore, because the coolant circulating through the second circuit C2 passes through the first valve 41 and the third valve 43, air near each valve that was not completely discharged in step S10 also circulates through the second circuit C2. Preferably, water is replenished from the reserve tank 14 while the closed-circuit circulation is being performed. Alternatively, when the water level in the reserve tank 14 drops to a certain level, the closed-circuit circulation may be temporarily stopped and water may be replenished to the reserve tank 14. The controller 50 may also have a function to notify an operator whether the water level in the reserve tank 14 has dropped to a certain level. In this manner, replenishment by circulating air accumulated in components, etc., through the circuits of the cooling system 100 further increases the water injection rate. In the closed-circuit circulation, the cooling water circulating through the first circuit C1 passes through the ePT 12, the first valve 41, and the second valve 42. Therefore, air accumulated near the ePT 12 and the valves that was not completely discharged in step S10 circulates through the first circuit C1. After the closed-circuit circulation has been performed for a certain period of time, the controller 50 executes the process of step S30.

[0060] The execution time of the closed-circuit circulation in step S20 is shorter than the execution time of the connected-circulation in step S10. In this way, by extending the execution time of the connected-circulation, which is efficient for gas-liquid substitution (air discharge), and shortening the execution time of the closed-circuit circulation, which is primarily intended for air circulation, it is possible to efficiently increase the water injection rate in a short time. In other words, it is possible to shorten the time required for water injection work at dealers, etc.

[0061] In step S30, the controller 50 again executes the connected circulation, which connects the first circuit C1 and the second circuit C2 to circulate the coolant. That is, the controller 50 controls the switching mechanism 40 so that the circuit of the cooling system 100 is again in the first pattern ( FIG. 3 ). As a result, the air in the first circuit C1 and the second circuit C2 circulated by the closed circuit circulation (step S20) is discharged from the reserve tank 14 to the outside of the cooling system 100. Therefore, the water injection rate of the circuit further increases. Note that the second connected circulation is also executed for a period of time, for example, until the gas-liquid exchange reaches equilibrium (the water injection rate approaches equilibrium). After the second connected circulation has been executed for a certain period of time, the controller 50 executes the process of step S40.

[0062] In step S40, the controller 50 disconnects the first circuit C1 from the second circuit C2 and resumes closed-circuit circulation, circulating the coolant. Specifically, the controller 50 controls the switching mechanism 40 so that the cooling system 100 resumes the second pattern ( FIG. 5 ). This allows the traces of air remaining in the circuits to be homogenized between the first circuit C1 and the second circuit C2. Preferably, water is replenished from the reserve tank 14 while the closed-circuit circulation is resumed (for the second time). Alternatively, if the water level in the reserve tank 14 drops to a certain level, the closed-circuit circulation may be temporarily stopped and water may be replenished to the reserve tank 14. The controller 50 may also have a function to notify the operator whether the water level in the reserve tank 14 has dropped to the certain level. By replenishing water while circulating the coolant through the closed circuit (the first circuit C1 and the second circuit C2), the air is more homogenized and the water injection rate is further increased. After the second closed circuit circulation is performed for a certain period of time, the controller 50 ends the water injection control.

[0063] The execution times of the second connected circulation in step S30 and the second closed-circuit circulation in step S40 are shorter than the execution time of the connected circulation in step S10. In this way, by extending the execution time of the first connected circulation, which is more efficient at gas-liquid replacement (air discharge), and shortening the execution times of the second connected circulation, which is less efficient at gas-liquid replacement (air discharge) than the first, and the second closed-circuit circulation, which is primarily intended to circulate air, it is possible to efficiently increase the water injection rate in a short period of time. In other words, the time required for water injection work by dealers, etc. can be shortened.

[0064] As described above, the cooling system 100 increases the water injection rate by alternately performing connected circulation and closed circuit circulation when injecting water into the circuit.

[0065] According to the above-described method for controlling the cooling system of this embodiment, the following effects can be obtained.

[0066] This embodiment provides a control method for a cooling system 100 including: a first circuit C1, a closed circuit through which coolant flows, including an ePT 12 (first component) to be cooled and a first water pump 11 that circulates the coolant; a second circuit C2, a closed circuit through which coolant flows, including a battery 22 (second component) to be cooled and a second water pump 21 that circulates the coolant; and a switching mechanism 40 that can connect or disconnect the first circuit C1 and the second circuit C2. According to this cooling system control method, when coolant is injected, the switching mechanism 40 is switched to alternately perform a connected circulation mode in which the first circuit C1 and the second circuit C2 are connected to circulate the coolant, and a closed circuit circulation mode in which the first circuit C1 and the second circuit C2 are disconnected to circulate the coolant. Air contained in the coolant in the first circuit C1 and the second circuit C2 is discharged to the outside of the cooling system 100 via a reserve tank (air discharge mechanism) 14 provided in the first circuit C1. In this way, the coolant is circulated through the circuits by alternating between the connected circulation and the closed circuit circulation, so that air remaining in each circuit (the first circuit C1, the second circuit C2) can be efficiently discharged to the outside of the system (outside the vehicle). Furthermore, the connected circulation and the closed circuit circulation can be performed by switching the switching mechanism 40, which can connect and disconnect the first circuit C1 and the second circuit C2. Therefore, a high water injection rate can be obtained without introducing high-performance equipment. In other words, a high water injection rate can be obtained using a simple method, and the system can be reduced in cost.

[0067] According to the cooling system control method of this embodiment, the execution time of the closed-circuit circulation is shorter than the execution time of the connected-circulation. In this way, by extending the execution time of the connected-circulation, which is efficient for gas-liquid exchange (air discharge), and shortening the execution time of the closed-circuit circulation, which is primarily intended for air circulation, it is possible to efficiently increase the water injection rate in a short time. In other words, it is possible to shorten the time required for water injection work at dealers, etc.

[0068] According to the cooling system control method of this embodiment, the connected circulation and the closed-circuit circulation are alternately performed twice. As a result, the air in the first circuit C1 and the second circuit C2 circulated in the first closed-circuit circulation is discharged to the outside of the cooling system 100 in the second connected circulation. Furthermore, the second closed-circuit circulation makes the small amount of air remaining in the circuits of the cooling system 100 more uniform in the first circuit C1 and the second circuit C2. This further increases the water injection rate.

[0069] According to the cooling system control method of this embodiment, the execution time of the second connected circulation and the second closed-circuit circulation is shorter than the execution time of the first connected circulation. In this way, by extending the execution time of the first connected circulation, which is more efficient at gas-liquid exchange (air discharge), and shortening the execution time of the second connected circulation, which is less efficient at gas-liquid exchange (air discharge) than the first, and the second closed-circuit circulation, which is primarily intended to circulate air, it is possible to efficiently increase the water injection rate in a short period of time. In other words, it is possible to shorten the time required for water injection work at dealers, etc.

[0070] In this embodiment, the components to be cooled that are arranged on the first circuit C1 are the ePT 12, and the components to be cooled that are arranged on the second circuit C2 are the battery 22, but the components to be cooled are not limited to these. In addition, it is possible to arbitrarily determine which components are arranged on the first circuit C1 or the second circuit C2.

[0071] In the present embodiment, the cooling system 100 includes the chiller 23 in the second circuit C2, and heat is exchanged between the coolant flowing through the second circuit C2 and the heat medium in the air-conditioning cycle AC. However, the present invention is not limited to this. That is, the cooling system 100 may not include the chiller 23 or the air-conditioning cycle AC.

[0072] Furthermore, in this embodiment, the reserve tank 14 serving as the air discharge mechanism is provided in the first circuit C1, but this is not limitative, and the reserve tank 14 may be provided in the second circuit C2.

[0073] In addition, in this embodiment, the reserve tank 14 is connected to the radiator 13, but this is not necessarily limited to this, and the reserve tank 14 may be independent or may be supported.

[0074] In addition, in this embodiment, the air exhaust mechanism is the reserve tank 14, but this is not limited to this, and any known air exhaust mechanism may be used as long as it is capable of exhausting air from the circuit of the cooling system 100.

[0075] In the present embodiment, the switching mechanism 40 includes the first valve 41, which is a four-way valve, and the second valve 42 and the third valve 43, which are three-way valves, but is not necessarily limited to this. Any known switching mechanism may be used as the switching mechanism 40 as long as it is configured to be able to connect or disconnect the first circuit C1 and the second circuit C2.

[0076] Furthermore, in this embodiment, the radiator 13 is used as the cooling mechanism, but the cooling mechanism is not limited to this as long as it is capable of exchanging heat with the cooling water.

[0077] Furthermore, from the viewpoint of the efficiency of discharging air from the circuits of the cooling system 100 and shortening the time required for the water injection operation, it is preferable to alternately perform the connected circulation and the closed circuit circulation twice as in the present embodiment, but this is not necessarily limited to this. For example, the connected circulation and the closed circuit circulation may be alternately performed three or more times.

[0078] As in this embodiment, the execution time of the closed circuit circulation (first time) is preferably shorter than the execution time of the connected circulation (first time), and the execution time of the second connected circulation and the second closed circuit circulation is preferably shorter than the execution time of the first connected circulation, but this is not necessarily limited to this. In other words, the execution times of the closed circuit circulation and the connected circulation may be set arbitrarily.

[0079] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A control method for a cooling system, comprising: a first circuit which is a closed circuit through which cooling water flows, and in which a first component to be cooled and a first water pump for circulating the cooling water are arranged; a second circuit which is a closed circuit through which cooling water flows, and in which a second component to be cooled and a second water pump for circulating the cooling water are arranged; a connecting circuit connecting the first circuit and the second circuit; a switching mechanism capable of connecting or disconnecting the first circuit and the second circuit; a cooling mechanism for cooling the cooling water flowing through the first circuit and the second circuit; and an air discharging mechanism provided in either one of the first circuit and the second circuit, wherein air contained in the cooling water of the first circuit and the second circuit is discharged to the outside of the cooling system through the air discharging mechanism, and when injecting the cooling water, the switching mechanism is switched so as to alternately execute a connected circulation in which the first circuit and the second circuit are connected to circulate the cooling water and a closed-circuit circulation in which the first circuit and the second circuit are disconnected to circulate the cooling water.

2. The control method for a cooling system according to claim 1, wherein the execution time of the closed-circuit circulation is shorter than the execution time of the connected circulation.

3. The control method for a cooling system according to claim 1 or 2, wherein the connected circulation and the closed-circuit circulation are alternately executed twice.

4. The control method for a cooling system according to claim 3, wherein the execution times of the second connected circulation and the second closed-circuit circulation are shorter than the execution time of the first connected circulation.

5. The control method for a cooling system according to claim 1 or 2, wherein the first component is an electric power train and the second component is a battery.

6. A cooling system comprising: a first circuit which is a closed circuit through which cooling water flows, and in which a first component to be cooled and a first water pump for circulating the cooling water are arranged; a second circuit which is a closed circuit through which cooling water flows, and in which a second component to be cooled and a second water pump for circulating the cooling water are arranged; a connecting circuit connecting the first circuit and the second circuit; a switching mechanism capable of connecting or disconnecting the first circuit and the second circuit; a cooling mechanism for cooling the cooling water flowing through the first circuit and the second circuit; an air discharge mechanism provided in the first circuit for discharging air contained in the cooling water of the first circuit to the outside; and a controller for controlling the operation of the switching mechanism, wherein the controller switches the switching mechanism so as to alternately execute a connected circulation in which the first circuit and the second circuit are connected to circulate the cooling water and a closed circuit circulation in which the first circuit and the second circuit are disconnected to circulate the cooling water during water filling.

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