Refrigerant circulation system for electric vehicles

Abstract

This invention provides a refrigerant circulation system for electric vehicles that can improve efficiency by optimizing the arrangement of the refrigerant circuits for the electric vehicle's battery and the refrigerant circuits for the interior air conditioning system. [Solution] The electric vehicle's refrigerant circulation system 1 includes a battery B that stores power for the electric vehicle's operation, a radiator 101, a first refrigerant circuit 100 through which a first refrigerant capable of cooling the battery B after being cooled by the radiator 101 circulates, and a second refrigerant circuit 200 for indoor air conditioning includes a condenser 204, a compressor 203, and an outdoor heat exchanger 201 through which a second refrigerant circulates, which absorbs heat from the outside air by the outdoor heat exchanger 201, is compressed by the compressor 203, and releases heat by the condenser 204. The outdoor heat exchanger 201 is positioned so that it can receive the exhaust heat from the radiator 101.

Description

Technical Field

[0001] The present invention relates to a refrigerant circulation system for an electric vehicle.

Background Art

[0002] An electric vehicle drives a driving motor using electric power supplied from a large-capacity battery, and the battery has a suitable temperature range.

[0003] For example, in the technology described in Patent Document 1, when it is necessary to raise the temperature of the cabin (inside) or the battery in an electric vehicle, a temperature control system for quickly raising the temperature of the battery is disclosed. This technology is configured such that, in a temperature control system including a water circuit for cooling electronic devices (motor, inverter, DC / DC converter, charger, etc.) and a refrigerant circuit for temperature control of the cabin or the battery, the waste heat of the radiator of the water circuit can be received by the heat exchanger of the refrigerant circuit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technology described in Patent Document 1 is configured to adjust the temperature of the cabin and the battery using the same water circuit, but there are also vehicles in which the refrigerant circuit for air conditioning in the vehicle interior and the refrigerant circuit for temperature adjustment of the battery are provided in separate systems. For example, among electric vehicles, in medium-sized to large-sized vehicles such as trucks and buses, the capacity of the mounted battery is larger than that of a passenger car, and a refrigerant circuit for cooling the battery is often provided independently.

[0006] Furthermore, because electric vehicles lack a heat source like an engine, they sometimes employ heat pump technology, which uses heat absorbed from the outside air to provide air conditioning. However, heat pumps have the problem of decreasing efficiency when the outside air temperature is low.

[0007] Therefore, the object of the present invention is to provide a refrigerant circulation system for an electric vehicle that can improve efficiency by optimizing the arrangement of the refrigerant circuit for the electric vehicle's battery and the refrigerant circuit for the interior air conditioning. [Means for solving the problem]

[0008] The present invention has been made to solve at least some of the aforementioned problems and can be realized in the following embodiments or application examples.

[0009] The refrigerant circulation system for an electric vehicle according to this application example comprises a battery for storing power for the electric vehicle to run, a first refrigerant circuit having a radiator through which a first refrigerant, cooled by the radiator and capable of cooling the battery, circulates, and a second refrigerant circuit for indoor air conditioning having a condenser, a compressor, and an outdoor heat exchanger through which a second refrigerant, which absorbs heat from the outside air by the outdoor heat exchanger, is compressed by the compressor, and releases heat by the condenser, circulates, with the outdoor heat exchanger positioned at a location where exhaust heat from the radiator reaches.

[0010] In this way, by positioning the outdoor heat exchanger of the second refrigerant circuit at a location where the exhaust heat from the radiator in the first refrigerant circuit for the battery reaches, the second refrigerant passing through the outdoor heat exchanger can absorb heat from the outside air heated by the exhaust heat from the radiator of the first refrigerant circuit. In other words, the heat absorption efficiency of the outdoor heat exchanger of the second refrigerant circuit can be improved by utilizing the exhaust heat for battery cooling. This makes it possible to suppress the decrease in efficiency of the second refrigerant circuit even when the outside air temperature is low.

[0011] Therefore, according to this application example, the arrangement of the refrigerant circuit for the electric vehicle's battery and the refrigerant circuit for the interior air conditioning can be optimized to improve efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] This is an overall configuration diagram showing one embodiment of the refrigerant circulation system for an electric vehicle according to the present invention. [Modes for carrying out the invention]

[0013] Next, with reference to Figure 1 as appropriate, an embodiment of the refrigerant circulation system for electric vehicles according to the present invention will be described.

[0014] The electric vehicle refrigerant circulation system 1 shown in Figure 1 is one embodiment of the electric vehicle refrigerant circulation system according to the present invention (the electric vehicle refrigerant circulation system according to this embodiment) and is installed in an electric vehicle. The electric vehicle here is not particularly limited, but it is preferably a medium-sized to large vehicle such as a truck or bus. The refrigerant circulation system 1 comprises a first refrigerant circuit 100 for adjusting the battery temperature, a second refrigerant circuit 200 for interior air conditioning, a third refrigerant circuit 300 for the heater of the interior air conditioning, a battery B, and a fan F. The battery B is for storing the power used to drive the electric vehicle equipped with the refrigerant circulation system 1.

[0015] The first refrigerant circuit 100 is a battery cooling circuit for circulating the first refrigerant to regulate (cool and warm up) the temperature of battery B. The first refrigerant circuit 100 is connected to a radiator 101, a first pump 102, a heater 103, and a chiller 104, each through a flow path for the first refrigerant. The first refrigerant is a liquid refrigerant, such as water.

[0016] The radiator 101 is a heat exchanger that performs heat exchange between the first refrigerant and the outside air. The first pump 102 is an electric pump for circulating the first refrigerant in the first refrigerant circuit 100. The heater 103 is a PTC (Positive Temperature Coefficient) heater for heating the first refrigerant as needed. The chiller 104 is a heat exchanger that performs heat exchange between the first refrigerant and the second refrigerant described later, and is mainly used when cooling the first refrigerant with the low-temperature second refrigerant.

[0017] In the first refrigerant circuit 100, the radiator 101 and the chiller 104 are arranged in parallel, and by opening and closing one or more flow path switching valves provided in the first refrigerant circuit 100 (not shown), it is possible to control whether the first refrigerant passes through either the radiator 101 or the chiller 104.

[0018] The second refrigerant circuit 200 is a heat pump circuit in which the second refrigerant circulates and heat exchange occurs between the first refrigerant and the third refrigerant (details of which will be described later). The second refrigerant circuit 200 has three flow paths: a first route R1 used for indoor heating, a second route R2 used for indoor cooling, and a third route R3 used for battery cooling. The second refrigerant is a gaseous refrigerant, such as HFO-1234yf.

[0019] First, the second refrigerant circuit 200 is equipped with an outdoor heat exchanger 201, an accumulator 202, a compressor 203, a condenser 204, an expansion valve 205, an evaporator 206, and the aforementioned chiller 104, in the first route R1.

[0020] The outdoor heat exchanger 201 is a heat exchanger that exchanges heat between the second refrigerant and the outside air. For example, the outdoor heat exchanger 201 absorbs heat from the outside air into the second refrigerant during indoor heating, and releases heat from the second refrigerant to the outside air during indoor cooling. The accumulator 202 is a gas-liquid separation device that separates the gas and liquid of the second refrigerant. The compressor 203 is a compressor that compresses the second refrigerant and raises the pressure and temperature of the second refrigerant. The condenser 204 is a condenser that exchanges heat between the second refrigerant and the third refrigerant described later, and releases heat from the second refrigerant, and heats the third refrigerant with the heated second refrigerant. The expansion valve 205 is a valve that reduces the pressure and temperature of the high-pressure second refrigerant. The evaporator 206 is an evaporator that exchanges heat between the second refrigerant and the indoor air during indoor cooling, and absorbs heat from the indoor air into the second refrigerant, and cools the indoor air.

[0021] Further, the second refrigerant circuit 200 includes the evaporator 206 in the second route R2 and the above-described chiller 104 in the third route R3. Both the second route R2 and the third route R3 are connected between the outdoor heat exchanger 201 and the accumulator 202.

[0022] The second refrigerant circuit 200 is provided with first switching valves 207, second switching valves 208, and third switching valves 209 for switching the flow paths of each route. Each switching valve is electrically connected to an ECU (Electronic Control Unit) mounted on the vehicle, which is not shown, and each switching valve is controlled to open and close by the ECU.

[0023] Specifically, the first switching valve 207 is provided between the outdoor heat exchanger 201 and the accumulator 202, the second switching valve 208 is provided between the outdoor heat exchanger 201 and the evaporator 206, and the third switching valve 209 is provided between the outdoor heat exchanger 201 and the chiller 104. During heating, the first switching valve 207 is opened, and the second switching valve 208 and the third switching valve 209 are closed, so that the second refrigerant circulates in the first route R1. During cooling, the first switching valve 207 is closed, and the second switching valve 208 is opened, so that in addition to the first route R1, the second refrigerant circulates in the second route R2, and the indoor air is cooled by the evaporator 206. When using the chiller 104, the first switching valve 207 is closed, and the third switching valve 209 is opened, so that in addition to the first route R1, the second refrigerant circulates in the third route R3, and heat exchange between the second refrigerant and the first refrigerant in the first refrigerant circuit 100 is performed by the chiller 104.

[0024] The third refrigerant circuit 300 is a heater circuit for circulating the third refrigerant to heat the heater core 303. The third refrigerant circuit 300 is connected such that the third pump 301, the above-described capacitor 204, the third heater 302, and the heater core 303 are respectively passed through the flow path of the third refrigerant. The third refrigerant is a liquid refrigerant, for example, water.

[0025] The third pump 301 is an electric pump for circulating the third refrigerant in the third refrigerant circuit 300. The third heater 302 is a PTC heater for heating the third refrigerant as needed. The heater core 303 is a heat exchanger that exchanges heat between the third refrigerant heated by the capacitor 204 or the third heater 302 and the indoor air.

[0026] In the refrigerant circulation system 1 configured in this way, the outdoor heat exchanger 201 in the second refrigerant circuit 200 is positioned so that it can receive the exhaust heat from the radiator 101 of the first refrigerant circuit 100. Specifically, the outdoor heat exchanger 201 is positioned between the radiator 101 and the fan F. The outdoor heat exchanger 201 and the radiator 101 form a roughly rectangular shape when viewed from the front, and are positioned so as to overlap each other when viewed from the direction of the airflow from the vehicle or the outside air drawn in by the fan F. In other words, the outside air drawn in by the airflow from the vehicle or the fan F passes through the radiator 101 and then through the outdoor heat exchanger 201, and the exhaust heat from the radiator 101 reaches the outdoor heat exchanger 201.

[0027] Next, we will explain the operation of the refrigerant circulation system 1 during heating. Since the operation during cooling is known, we will omit the explanation.

[0028] First, let's explain the operation of the refrigerant circulation system 1 when using heating. When heating is in use, as described above, the second refrigerant circulates through the first route R1 in the second refrigerant circuit 200. Specifically, the second refrigerant absorbs heat from the outside air in the outdoor heat exchanger 201, is separated into gas and liquid in the accumulator 202, and is then compressed by the compressor 203 to increase its pressure and temperature, which heats the third refrigerant in the third refrigerant circuit 300 by the condenser 204. After passing through the condenser 204, the second refrigerant rapidly expands in the expansion valve 205 to decrease its pressure and temperature, and then absorbs heat again in the outdoor heat exchanger 201. Then, in the third refrigerant circuit 300, the third refrigerant heated in the condenser 204 heats the indoor air in the heater core 303 to heat the room.

[0029] At this time, if the battery B is being cooled in the first refrigerant circuit 100, the first refrigerant absorbs heat from the battery B to cool it, and the absorbed heat is discharged to the outside air by the radiator 101 (exhaust heat). This exhaust heat is drawn in by the airflow while driving or by the fan F and moves to the outdoor heat exchanger 201 side, warming the outdoor heat exchanger 201. As the outdoor heat exchanger 201 is warmed in this way, the heat absorption of the first refrigerant in the outdoor heat exchanger 201 is promoted.

[0030] According to the refrigerant circulation system 1 of this embodiment, by positioning the outdoor heat exchanger 201 of the second refrigerant circuit 200 at a location where the exhaust heat from the radiator 101 in the first refrigerant circuit 100 for the battery reaches, the second refrigerant passing through the outdoor heat exchanger 201 can absorb heat from the outside air heated by the exhaust heat from the radiator 101 of the first refrigerant circuit 100. In other words, the heat absorption efficiency of the outdoor heat exchanger 201 of the second refrigerant circuit 200 can be improved by utilizing the exhaust heat for battery cooling. As a result, even when the outside air temperature is low, the decrease in efficiency of the second refrigerant circuit 200 can be suppressed.

[0031] In this way, the refrigerant circulation system 1 can improve efficiency by optimizing the arrangement of the first refrigerant circuit 100 for the electric vehicle's battery and the second refrigerant circuit 200, which is a heat pump circuit for indoor air conditioning.

[0032] Furthermore, the temperature of the radiator 101 when cooling battery B is around 30-40°C, which is higher than the outside temperature that generally requires heating (below 20°C). This improves the heat absorption efficiency of the outdoor heat exchanger 201 during heating, and since there is no significant difference from the outside temperature that requires cooling, it does not worsen the efficiency of the outdoor heat exchanger 201 during cooling.

[0033] This concludes the description of embodiments of the present invention, but the embodiments of the present invention are not limited to these embodiments. For example, the outdoor heat exchanger 201 only needs to be positioned where it can receive the exhaust heat from the radiator 101, so it does not need to be installed between the fan F and the radiator 101, but may be installed downstream (downstream of the radiator 101) in the airflow path of an electric vehicle equipped with the refrigerant circulation system 1. [Explanation of Symbols]

[0034] 1. Refrigerant circulation system for electric vehicles 100 1st refrigerant circuit 101 Radiator 102 Pump No. 1 103 Heater 104 Chiller 200 Second refrigerant circuit 201 Outdoor heat exchanger 202 Accumulator 203 Compressor 204 Capacitor 205 Expansion valve 206 Evaporator 207 First changeover valve 208 Second switching valve 209 Third switching valve 300 Third refrigerant circuit 301 Pump No. 3 302 Heater 303 Heater core B Battery F Fan R1 Route 1 Route R2, Route 2 Route 3, Third Route

Claims

[Claim 1] A refrigerant circulation system for an electric vehicle, A battery for storing power for the electric vehicle to run, A first refrigerant circuit having a radiator, through which a first refrigerant, cooled by the radiator and capable of cooling the battery, circulates; The system includes a second refrigerant circuit for indoor air conditioning, which comprises a condenser, a compressor, and an outdoor heat exchanger, and in which a second refrigerant circulates, absorbing heat from the outside air by the outdoor heat exchanger, being compressed by the compressor, and releasing heat by the condenser. The outdoor heat exchanger is positioned so that it can receive the exhaust heat from the radiator. Refrigerant circulation system for electric vehicles.

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