Vehicle cooling system

Abstract

To provide a vehicle cooling system which can maintain EV travel even when indoor air-conditioning takes precedence and battery cooling is inactive.SOLUTION: A vehicle cooling system includes a freezing cycle circuit 20 having an evaporator 23 which cools the air to be supplied into a vehicle cabin, and a chiller 25 which exchanges heat with a low-temperature-side cooling water circuit 30 which cools a battery 11, which are in parallel to each other. The low-temperature-side cooling water circuit 30 includes the chiller 25, a circuit for cooling the battery 11, a circuit for cooling a PCU 12, and a low-temperature-side radiator 35 which dissipates heat from circulating cooling water, which are in parallel to each other. In the freezing cycle circuit 20, coolant circulates only in the evaporator 23. When the temperature of the battery 11 is equal to or higher than a predetermined battery temperature and when the temperature of cooling water in the low-temperature-side cooling water circuit 30 is equal to or lower than a predetermined cooling water temperature, the cooling water circulates only in the circuit for cooling the battery 11 and the low-temperature-side radiator 35 in the low-temperature-side cooling water circuit 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle cooling system that cools a battery using a refrigerant for vehicle interior air conditioning.

Background Art

[0002] In a vehicle cooling system, the battery may be cooled using a refrigerant for vehicle interior air conditioning. In the vehicle cooling system, an evaporator that cools the air blown into the vehicle interior and a chiller that cools the cooling water for cooling the battery are provided in parallel. For example, in the vehicle cooling system disclosed in Patent Document 1, when vehicle interior air conditioning is prioritized due to a high cooling load or the like, the refrigerant circulation to the chiller is stopped and battery cooling is suspended.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the above-described vehicle cooling system is mounted on, for example, a PHEV (Plug-in Hybrid Electric Vehicle), when driving in the EV mode (a mode in which the vehicle runs only on the power from the battery) while battery cooling is suspended, the battery temperature rises during driving, and in some cases, the engine may be activated because EV driving cannot be maintained.

[0005] Therefore, an object of the present invention is to provide a vehicle cooling system that can maintain EV driving even when vehicle interior air conditioning is prioritized and battery cooling is suspended.

Means for Solving the Problems

[0006] The vehicle cooling system according to the present invention is a vehicle cooling system that cools a battery using a refrigerant for vehicle interior air conditioning, and has a refrigeration cycle circuit in which an evaporator that cools the air blown into the vehicle interior and a chiller that exchanges heat with a cooling water circuit for cooling the battery are provided in parallel. The cooling water circuit has a chiller, a circuit for cooling the battery, a circuit for cooling in-vehicle units, and a radiator that dissipates heat from the circulating cooling water, all provided in parallel. In the refrigeration cycle circuit, the refrigerant is circulated only through the evaporator. When the temperature of the battery is equal to or higher than a predetermined battery temperature and the temperature of the cooling water in the cooling water circuit is equal to or lower than a predetermined cooling water temperature, the cooling water is circulated only through the circuit for cooling the battery and the radiator in the cooling water circuit.

Effects of the Invention

[0007] According to the vehicle cooling system of the present invention, even when the vehicle interior air conditioning is prioritized and battery cooling is suspended, EV driving can be maintained.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, an example of an embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present invention and can be appropriately changed according to applications, purposes, specifications, etc.

[0010] The cooling system 10 as a vehicle cooling system cools the battery 11 using the refrigerant for the in-vehicle air conditioner. According to the cooling system 10, although details will be described later, even when the cooling of the battery 11 is suspended with priority given to the in-vehicle air conditioner, the EV driving can be maintained.

[0011] <Vehicle> The cooling system 10 of the present embodiment is mounted on a PHEV (not shown) as a vehicle. The PHEV is a vehicle that can charge the battery 11 of an HEV (Hybrid Electric Vehicle) that runs by driving a gasoline engine and a motor from an external power supply facility. However, the cooling system 10 of the present embodiment may be mounted on an HEV.

[0012] <Cooling system> The cooling system 10 will be described with reference to FIGS. 1 and 2.

[0013] As shown in FIG. 1, the cooling system 10 includes a refrigeration cycle circuit 20 that cools the air blown into the vehicle interior and cools the battery 11, a low-temperature side cooling water circuit 30 as a cooling water circuit that absorbs heat by the chiller 25 of the refrigeration cycle circuit 20, a high-temperature side cooling water circuit 40 that is heated by the water-cooled condenser 22 of the refrigeration cycle circuit 20, and a cooling ECU (Electronic Control Unit) 50 that controls each device of the refrigeration cycle circuit 20, the low-temperature side cooling water circuit 30, and the high-temperature side cooling water circuit 40.

[0014] A battery temperature sensor 61 for detecting the temperature of the battery 11 is provided in the battery 11.

[0015] The refrigeration cycle circuit 20 includes a compressor 21 that compresses a refrigerant, a water-cooled condenser 22 that heats (rejects heat) the cooling water circulating in the high-temperature side cooling water circuit 40, an evaporator 23 that cools the air blown into the vehicle interior, an evaporator side expansion valve 24 that adjusts the refrigerant circulation amount to the evaporator 23, a chiller 25 that absorbs heat from the cooling water circulating in the low-temperature side cooling water circuit 30, and a chiller side expansion valve 26 that adjusts the refrigerant circulation amount to the chiller 25. In the refrigeration cycle circuit 20, the evaporator 23 and the chiller 25 are connected in parallel.

[0016] The low-temperature side cooling water circuit 30 as the cooling water circuit is a circuit that circulates the low-temperature side cooling water by a first low-temperature side water pump 31 and a second low-temperature side water pump 32. The low-temperature side cooling water circuit 30 includes the above-described chiller 25, a battery cooler 33 that cools the battery 11, a unit cooler 34 that cools the PCU (Power Control Unit) 12, a low-temperature side radiator 35 that radiates the low-temperature side cooling water to the air, and a flow rate adjustment valve 36 that will be described in detail later. The chiller 25, the battery cooler 33, the unit cooler 34, and the low-temperature side radiator 35 are connected in parallel, respectively. The first low-temperature side water pump 31 is provided on the downstream side of the low-temperature side radiator 35, and the second low-temperature side water pump 32 is provided on the downstream side of the chiller 25.

[0017] The flow rate adjustment valve 36 has respective circuits leading to the chiller 25, the battery cooler 33, the unit cooler 34, and the low-temperature side radiator 35 connected thereto, and can switch between a state of communicating at least the chiller 25 and the battery cooler 33, a state of communicating the battery cooler 33 and the low-temperature side radiator 35, and a state of communicating the unit cooler 34 and the low-temperature side radiator 35, and can adjust the flow rate in each state.

[0018] A low-temperature side cooling water temperature sensor 62 for detecting the temperature of the low-temperature side cooling water is provided on the upstream side of the battery cooler 33.

[0019] The high-temperature side cooling water circuit 40 is a circuit that circulates high-temperature side cooling water by means of a high-temperature side water pump 41, and has the above-described water-cooled condenser 22 and a high-temperature side radiator 42 that dissipates the high-temperature side cooling water into the air.

[0020] The cooling ECU 50 controls each device of the refrigeration cycle circuit 20, the low-temperature side cooling water circuit 30, and the high-temperature side cooling water circuit 40 as described above. The cooling ECU 50 executes battery cooling control, the details of which will be described later, in the cooling system 10. The cooling ECU 50 is a computer having a processor 51 that performs information processing therein and a memory 52 that stores software, programs, or data executed by the processor 51.

[0021] The cooling ECU 50 is connected to the compressor 21, the evaporator side expansion valve 24, the chiller side expansion valve 26, the first low-temperature side water pump 31, the second low-temperature side water pump 32, the flow rate adjustment valve 36, the high-temperature side water pump 41, the battery temperature sensor 61, and the low-temperature side cooling water temperature sensor 62.

[0022] As shown in FIG. 2, the cooling ECU 50 has an air-conditioning priority section 53, a battery temperature determination section 54, a low-temperature side cooling water temperature determination section 55, and a battery cooling section 56, the details of which will be described later. The air-conditioning priority section 53, the battery temperature determination section 54, the low-temperature side cooling water temperature determination section 55, and the battery cooling section 56 are realized by the processor 51 executing a program stored in the memory 52.

[0023] When the air-conditioning priority section 53 determines that the cooling load is high, it suspends the cooling of the battery 11 and gives priority to the vehicle interior air-conditioning. More specifically, in the refrigeration cycle circuit 20, the chiller side expansion valve 26 is closed and the evaporator side expansion valve 24 is adjusted so that the refrigerant circulates only through the evaporator 23 without circulating through the chiller 25.

[0024] As conditions for determining that the cooling load is high, for example, it is preferable that the outside air temperature detected by an outside air temperature sensor (not shown) is equal to or higher than a predetermined outside air temperature, the inside air temperature detected by an inside air temperature sensor (not shown) is equal to or higher than a predetermined inside air temperature, the evaporator temperature detected by an evaporator temperature sensor (not shown) is equal to or higher than a predetermined evaporator temperature, and the like.

[0025] The battery temperature determination unit 54 detects the battery temperature of the battery 11 from the battery temperature sensor 61 and determines whether the battery temperature is equal to or higher than a predetermined battery temperature.

[0026] Here, while the vehicle interior air conditioning is prioritized by the air conditioning priority unit 53 and the cooling of the battery 11 is suspended, when driving in the EV mode, the temperature of the battery 11 may rise during driving, and the engine may be activated because the EV driving cannot be maintained. Therefore, when the battery 11 can be cooled by the low-temperature side cooling water, the battery 11 is cooled by the low-temperature side cooling water so as to maintain the EV driving without activating the engine.

[0027] The low-temperature side cooling water temperature determination unit 55 detects the low-temperature side cooling water temperature from the low-temperature side cooling water temperature sensor 62 and determines whether the low-temperature side cooling water temperature is equal to or lower than a predetermined cooling water temperature.

[0028] The battery cooling unit 56 cools the battery 11 with the low-temperature side cooling water when it is determined by the battery temperature determination unit 54 that the battery temperature is equal to or higher than a predetermined battery temperature while the cooling of the battery 11 is suspended by the air conditioning priority unit 53, and it is determined by the low-temperature side cooling water temperature determination unit 55 that the low-temperature side cooling water temperature is equal to or lower than a predetermined cooling water temperature, and even when the cooling of the battery 11 is suspended via the chiller 25 by the refrigeration cycle circuit 20, it is determined that the battery 11 can be cooled by the low-temperature side cooling water.

[0029] Specifically, the battery cooling unit 56 places the battery cooler 33 and the low-temperature radiator 35 in communication with each other by means of the flow rate adjustment valve 36 in the low-temperature side cooling water circuit 30, and cools the battery 11 with the low-temperature side cooling water by circulating the low-temperature side cooling water only through the battery cooler 33 and the low-temperature radiator 35.

[0030] According to the battery cooling unit 56, even when the cooling load is high and the vehicle interior air conditioning is prioritized and battery cooling is suspended, EV travel can be maintained. More specifically, even while the cooling load is high and the vehicle interior air conditioning is prioritized and battery cooling is suspended, if the battery 11 can be cooled by the low-temperature side cooling water, EV travel can be maintained without operating the engine by cooling the battery 11 with the low-temperature side cooling water.

[0031] <Battery Cooling Control> The flow of battery cooling control will be described with reference to FIG. 3.

[0032] In step S11, it is determined by the air conditioning priority unit 53 whether cooling of the battery 11 is suspended and the vehicle interior air conditioning is prioritized. If the vehicle interior air conditioning is prioritized, the process proceeds to step S12. If the vehicle interior air conditioning is not prioritized, the process proceeds to step S15.

[0033] In step S12, it is determined by the battery temperature determination unit 54 whether the battery temperature is equal to or higher than a predetermined battery temperature. If the battery temperature is equal to or higher than the predetermined battery temperature, the process proceeds to step S13. If the battery temperature is lower than the predetermined battery temperature, the process proceeds to step S15.

[0034] Note that in step S12, the battery temperature determination unit 54 preferably provides hysteresis between the threshold value for determining that the battery temperature is equal to or higher than the predetermined battery temperature and the threshold value for the battery temperature to return from the state where the battery temperature is equal to or higher than the predetermined battery temperature to the normal state (the state where the battery temperature is lower than the predetermined battery temperature).

[0035] In step S13, the low-temperature-side cooling water temperature determination unit 55 determines whether the low-temperature-side cooling water temperature is equal to or lower than a predetermined cooling water temperature. If the low-temperature-side cooling water temperature is equal to or lower than the predetermined cooling water temperature, the process proceeds to step S14. If the low-temperature-side cooling water temperature is higher than the predetermined cooling water temperature, the process proceeds to step S15.

[0036] Note that in step S13, the low-temperature-side cooling water temperature determination unit 55 preferably provides hysteresis for the threshold value at which the low-temperature-side cooling water temperature is determined to be equal to or lower than the predetermined cooling water temperature and the threshold value at which the low-temperature-side cooling water temperature returns from a state where it is equal to or lower than the predetermined cooling water temperature to the normal state (a state where the low-temperature-side cooling water temperature becomes higher than the predetermined cooling water temperature).

[0037] In step S14, the battery cooling unit 56 makes the battery cooler 33 and the low-temperature-side radiator 35 communicate with each other by the flow rate adjustment valve 36, and cools the battery 11 with the low-temperature-side cooling water.

[0038] In step S15, the flow rate adjustment valve 36 makes the unit cooler 34 and the low-temperature-side radiator 35 communicate with each other, and cools the PCU 12 with the low-temperature-side cooling water.

[0039] Note that the present invention is not limited to the above-described embodiments and their modified examples, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

Explanation of Reference Numerals

[0040] 10 Cooling system (vehicle cooling system), 11 Battery, 20 Refrigeration cycle circuit, 21 Compressor, 22 Water-cooled condenser, 23 Evaporator, 24 Evaporator side expansion valve, 25 Chiller, 26 Chiller side expansion valve, 30 Low-temperature side cooling water circuit (cooling water circuit), 31 First low-temperature side water pump, 32 Second low-temperature side water pump, 33 Battery cooler, 34 Unit cooler, 35 Low-temperature side radiator, 36 Flow rate adjustment valve, 40 High-temperature side cooling water circuit, 41 High-temperature side water pump, 42 High-temperature side radiator, 50 Cooling ECU, 51 Processor, 52 Memory, 53 Air conditioning priority section, 54 Cooling water temperature determination section, 55 Battery temperature determination section, 56 Battery cooling section, 61 Battery temperature sensor, 62 Low-temperature side cooling water temperature sensor

Claims

Claim 1 A vehicle cooling system that cools a battery using a refrigerant for in-vehicle air conditioning, comprising: a refrigeration cycle circuit in which an evaporator that cools air blown into the vehicle interior and a chiller that exchanges heat with a cooling water circuit that cools the battery are provided in parallel; the cooling water circuit includes, in parallel, the chiller, a circuit that cools the battery, a circuit that cools in-vehicle units, and a radiator that dissipates heat from the circulating cooling water; in the refrigeration cycle circuit, only the evaporator circulates the refrigerant, and when the temperature of the battery is equal to or higher than a predetermined battery temperature and the temperature of the cooling water in the cooling water circuit is equal to or lower than a predetermined cooling water temperature, only the circuit that cools the battery and the radiator in the cooling water circuit circulate the cooling water; A vehicle cooling system.

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