Cooling system

Abstract

To provide a cooling system capable of suppressing increase in a condenser heat discharge amount when the temperature of an evaporator is raised in order to reduce the heat discharge amount of the condenser, even in the case where an air conditioner refrigerant flow passage includes a first flow passage toward the evaporator and a second flow passage toward a chiller.SOLUTION: In the case where it is a cooling operation mode in which an air conditioner refrigerant flows in a first flow passage 30 and a cooling battery mode in which the air conditioner refrigerant also flows in a second flow passage 40, the temperature of an evaporator 32 is raised, and an upper limit of the opening of a second expansion valve 41 is fixed. Since the temperature of the evaporator 32 is raised, an air conditioner load can be reduced, and the heat discharge amount of a condenser 22 can be reduced. Since the upper limit of the opening of the second expansion valve 41 is fixed, the upper limit of the flow rate of the air conditioner refrigerant flowing in the second expansion valve 41 can be fixed, thereby, the amount of the air conditioner refrigerant flowing into a chiller 42 is suppressed, a heat exchange rate in the chiller 42 can be suppressed, and the increase in the heat discharge amount of the condenser 22 can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle cooling system that uses an air conditioner refrigerant to cool the interior of a vehicle cabin and to cool battery coolant. [Background technology]

[0002] Conventionally, when the temperature of engine coolant (hereinafter also referred to as engine water temperature) or the temperature of coolant for a motor, PCU (Power Control Unit), etc. (hereinafter also referred to as HV water temperature) is high, there is a technology that increases the temperature of an evaporator installed in the flow path through which air conditioner refrigerant flows, thereby reducing the air conditioner load and reducing the amount of heat dissipation from a condenser installed in the air conditioner refrigerant flow path (for example, Patent Document 1).

[0003] Incidentally, some PHEVs (Plug-in Hybrid Electric Vehicles) and BEVs (Battery Electric Vehicles) that have secondary batteries have an air conditioner refrigerant flow path that has a first flow path leading to an evaporator and a second flow path that is arranged in parallel with the first flow path and leads to a chiller that cools the battery coolant. Even if the above-mentioned conventional technology is applied to this and the evaporator temperature is raised when the engine water temperature or HV water temperature is high, in a cooling battery mode in which the air conditioner refrigerant flows through the second flow path, the heat exchange capacity of the chiller increases relatively by the amount of the evaporator temperature increase, and there is a risk that the amount of heat dissipated by the condenser will not change significantly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-195037 A Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a cooling system that can suppress an increase in the amount of heat dissipated by the condenser when the temperature of the evaporator is raised to reduce the amount of heat dissipated by the condenser, even when the air conditioner refrigerant flow path has a first flow path leading to an evaporator and a second flow path leading to a chiller. [Means for solving the problem]

[0006] The present invention which achieves the above object is as follows. (1) A cooling system in which a refrigerant flow path through which an air conditioner refrigerant flows includes a first flow path leading to a first expansion valve and an evaporator, and a second flow path arranged in parallel with the first flow path leading to a second expansion valve and a chiller, and capable of cooling a battery by cooling a battery coolant in the chiller using the air conditioner refrigerant, A cooling system characterized in that, when the system is in a cooling operation mode in which the air conditioner refrigerant flows through the first flow path and in a cooling battery mode in which the air conditioner refrigerant also flows through the second flow path, the temperature of the evaporator is increased and an upper limit of the opening degree of the second expansion valve is fixed. Effect of the Invention

[0007] In the cooling system of (1) above, when the system is in cooling operation mode in which air conditioner refrigerant flows through the first flow path and in cooling battery mode in which air conditioner refrigerant also flows through the second flow path, the temperature of the evaporator is raised and the upper limit of the opening of the second expansion valve is fixed, thereby obtaining the following effects. Since the temperature of the evaporator is increased, the air conditioner load (cooling load) can be reduced, and the amount of heat dissipated by the condenser can be reduced. Furthermore, since the upper limit of the opening degree of the second expansion valve is fixed, the upper limit of the flow rate of the air conditioner refrigerant flowing through the second expansion valve can be fixed, thereby suppressing the amount of air conditioner refrigerant flowing to the chiller and suppressing an increase in the amount of heat dissipated by the condenser. Therefore, even if the air conditioner refrigerant flow path has a first flow path toward the evaporator and a second flow path that is arranged in parallel with the first flow path and toward the chiller, it is possible to suppress an increase in the amount of heat dissipated by the condenser when the temperature of the evaporator is increased to reduce the amount of heat dissipated by the condenser. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a cooling system according to an embodiment of the present invention. [Diagram 2] 3 is a control flowchart of the cooling system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A cooling system 10 according to an embodiment of the present invention will now be described with reference to the drawings.

[0010] The vehicle in which the cooling system 10 is installed is a PHEV, but may also be a BEV.

[0011] As shown in FIG. 1, the cooling system 10 has a refrigerant flow path P1 through which an air conditioner refrigerant flows, which has a first flow path 30 leading to a first expansion valve 31 and an evaporator 32, and a second flow path 40 arranged in parallel to the first flow path 30 and leading to a second expansion valve 41 and a chiller 42.The cooling system is capable of cooling a battery V by cooling battery cooling water in the chiller 42 using the air conditioner refrigerant.

[0012] The air conditioner refrigerant can be circulated through a refrigerant flow path P1 by the refrigeration cycle 50. The refrigeration cycle 50 has a common flow path 20, a first flow path 30, and a second flow path 40 as the refrigerant flow path P1 through which the air conditioner refrigerant flows.

[0013] A compressor 21 and a condenser 22 are arranged in the common flow path 20. The compressor 21 compresses and discharges the air conditioner refrigerant circulating in the refrigeration cycle 50. This discharge pressure can be detected by a pressure sensor 23 arranged downstream of the compressor 21 and upstream of the condenser 22. The condenser 22 cools the air conditioner refrigerant by exchanging heat between the air conditioner refrigerant discharged from the compressor 21 and the air outside the vehicle cabin. Only one compressor 21 and one condenser 22 are provided in the refrigeration cycle 50.

[0014] The first flow path 30 is located downstream of the branching portion 24 downstream of the condenser 22 and upstream of the junction portion 25 upstream of the compressor 21, and is a flow path in which a first expansion valve 31 and an evaporator 32 are arranged. The first expansion valve 31 is an electric expansion valve. Note that reference numeral 33 in the figure denotes a temperature sensor for detecting the air conditioner refrigerant temperature downstream of the evaporator 32, and reference numeral 34 denotes an evaporation pressure regulator (EPR) that is arranged downstream of the evaporator 32 and upstream of the compressor 21 to adjust the suction pressure of the compressor 21 to be equal to or lower than a certain value.

[0015] In the cooling operation mode, the air conditioner refrigerant that has flowed through the common flow path 20 flows into the first flow path 30. The air conditioner refrigerant flowing through the first flow path 30 is decompressed and its flow rate is adjusted by the first expansion valve 31, and then flows into the evaporator 32. In the evaporator 32, the air conditioner refrigerant absorbs heat from the surrounding air, and the air around the evaporator 32 is cooled. This air is discharged into the vehicle cabin to cool the vehicle cabin.

[0016] The second flow path 40 is a flow path arranged in parallel with the first flow path 30, is located downstream of the branching section 24 and upstream of the merging section 25, and is a flow path in which a second expansion valve 41 and a chiller 42 are arranged. The second expansion valve 41 is an electric expansion valve. Note that reference numeral 43 in the figure denotes a temperature sensor for detecting the air conditioner refrigerant temperature downstream of the chiller 42.

[0017] The second flow path 40 is a flow path for cooling the battery V by using an air conditioner refrigerant to cool the battery cooling water when the temperature of the battery V rises. In addition to the battery V and the chiller 42, a water pump 60 that compresses and discharges the battery cooling water is disposed in the cooling water circuit P2 through which the battery cooling water circulates, and the action of this water pump 60 enables the battery cooling water to circulate through the cooling water circuit P2. The temperature of the battery V can be detected by a temperature sensor (not shown) attached to the battery V. However, the temperature of the battery V may also be detected by a water temperature sensor 61 disposed in the cooling water circuit P2 downstream of the battery V and upstream of the water pump 60.

[0018] In the cooling battery mode in which the battery V is cooled by cooling the battery cooling water, the air conditioner refrigerant that has flowed through the common flow path 20 flows into the second flow path 40. The air conditioner refrigerant flowing through the second flow path 40 is depressurized and its flow rate is adjusted by the second expansion valve 41, and then flows into the chiller 42. In the chiller 42, heat exchange occurs between the air conditioner refrigerant and the battery cooling water, and the battery cooling water is cooled. The cooled battery cooling water is caused to flow through the battery V, thereby cooling the battery V. In addition, a water temperature sensor 62 is disposed in the coolant circuit P2 downstream of the chiller 42 and upstream of the battery V, and the water temperature sensor 62 can be used to detect the battery cooling water temperature downstream of the chiller 42.

[0019] In the present invention, as in the conventional case, when the vehicle is in cooling operation mode and the engine water temperature (not shown) or the HV water temperature (not shown) is high, the target temperature of the evaporator 32 in the first flow path 30 is increased to reduce the air conditioning load and reduce the amount of heat dissipated by the condenser 22. However, when the temperature of the battery V is high and the second flow path 40 is also flowing in the cooling battery mode, the heat exchange capacity of the chiller 42 will increase relatively by the amount that the temperature of the evaporator 32 is increased, and there is a risk that a situation will arise in which the amount of heat dissipated by the condenser 22 does not change significantly. Therefore, in the present invention, when the cooling operation mode is set in which the air conditioner refrigerant flows through the first flow path 30 and when the cooling battery mode is set in which the air conditioner refrigerant also flows through the second flow path 40, the temperature of the evaporator 32 is increased and the upper limit of the opening degree of the second expansion valve 41 is fixed. This control can be executed by a control device 70, which is a component of the cooling system 10. The control device 70 has the evaporator 32 and the second expansion valve 41 connected to its output side.

[0020] The reason for fixing the upper limit of the opening degree of the second expansion valve 41 is that it is possible to fix the upper limit of the flow rate of the air conditioner refrigerant flowing through the second expansion valve 41, thereby reducing the amount of air conditioner refrigerant flowing to the chiller 42 and suppressing an increase in the amount of heat dissipated by the condenser 22.

[0021] 2 is a control flowchart of the control device 70 in the cooling system 10 of the present invention. The control shown in FIG. 2 is executed at predetermined time intervals during the cooling operation mode in which the air conditioner refrigerant flows through the first flow path 30.

[0022] First, in step S1, the control device 70 determines whether the engine water temperature or the HV water temperature is higher than a predetermined value. If it is determined in step S1 that the engine water temperature or the HV water temperature is equal to or lower than the predetermined value, the process proceeds to step S5, where it does nothing and proceeds directly to the end step. On the other hand, if it is determined in step S1 that the engine water temperature or the HV water temperature is higher than the predetermined value, the process proceeds to step S2.

[0023] In step S2, it is determined whether or not the system is in cooling battery mode, in which the air conditioner refrigerant flows through the second flow path 40. If it is determined in step S2 that the system is not in cooling battery mode, the process proceeds to step S4, in which a signal to increase the target temperature of the evaporator 32 by a predetermined amount is output to the evaporator 32, and the process proceeds to the end step. On the other hand, if it is determined in step S2 that the system is in cooling battery mode, the process proceeds to step S3, in which a signal to increase the target temperature of the evaporator 32 by a predetermined amount is output to the evaporator 32, and a signal to fix the upper limit of the opening degree of the second expansion valve 41 to a predetermined value (%) is output to the second expansion valve 41, and the process proceeds to the end step.

[0024] Next, the operation and effects of the embodiment of the present invention will be described. In this embodiment of the present invention, when the cooling operation mode is set in which the air conditioner refrigerant flows through the first flow path 30 and the cooling battery mode is set in which the air conditioner refrigerant also flows through the second flow path 40, the temperature of the evaporator 32 is raised and the upper limit of the opening degree of the second expansion valve 41 is fixed, thereby obtaining the following effects. Since the temperature of the evaporator 32 is increased, the air conditioner load (cooling load) can be reduced, and the amount of heat radiation of the condenser 22 can be reduced. In addition, since the upper limit of the opening degree of the second expansion valve 41 is fixed, the upper limit of the flow rate of the air conditioner refrigerant flowing through the second expansion valve 41 can be fixed, thereby suppressing the amount of air conditioner refrigerant flowing to the chiller 42 and suppressing the heat exchange rate in the chiller 42, and suppressing an increase in the amount of heat radiation of the condenser 22. Therefore, even if the flow path of the air conditioner refrigerant has the first flow path 30 toward the evaporator 32 and the second flow path 40 arranged in parallel with the first flow path 30 and toward the chiller 42, when the temperature of the evaporator 32 is increased to reduce the amount of heat radiation of the condenser 22, the increase in the amount of heat radiation of the condenser 22 can be suppressed. [Explanation of symbols]

[0025] 10 Cooling System 20 Common flow path 21 Compressor 22 Capacitor 24 Branch 25 Junction 30 First flow path 31 First expansion valve 32 Evaporator 40 Second Flow Path 41 Second expansion valve 42 Chiller 50 Refrigeration Cycle 60 Water Pump 70 Control device P1 Coolant flow path P2 cooling water circuit V battery

Claims

[Claim 1] A cooling system in which a refrigerant flow path through which an air conditioner refrigerant flows includes a first flow path leading to a first expansion valve and an evaporator, and a second flow path that is arranged in parallel with the first flow path and leads to a second expansion valve and a chiller, and the air conditioner refrigerant is used to cool a battery cooling water in the chiller, thereby performing battery cooling, A cooling system characterized in that, when the system is in a cooling operation mode in which the air conditioner refrigerant flows through the first flow path and in a cooling battery mode in which the air conditioner refrigerant also flows through the second flow path, the temperature of the evaporator is increased and an upper limit of the opening degree of the second expansion valve is fixed.

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