JPH06293214A - Cooling system for electric vehicle - Google Patents

Abstract

PURPOSE:To carry out harmless and efficient cooling by leading a hot temperature and high pressure compressed refrigerant gas into an accumulator located at the low pressure side in a refrigerating cycle. CONSTITUTION:A low temperature, low pressure refrigerant which is reduced in pressure in an expansion valve 7b is fed to an accumulator 10 through a solenoid valve 9a after cooling an electric motor 6. However, when a pressure detected by a pressure sensor 12 is lower than a suction pressure of a compressor 1, it cannot be adjusted stably by a suction pressure regulating valve 11 only. Therefore, when a pressure valve is lowered than the suction pressure, a solenoid valve 9b on a bypass line 14 is opened to lead a part of high temperature, high pressure refrigerant gas into the accumulator 10. Thus the stable operation of refrigerating cycle under a specified pressure condition can be maintained, and also its equipment constitution can be facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for an electric vehicle that is pollution-free and can efficiently and freely carry people or cargo.

[0002]

2. Description of the Related Art Electric vehicles have been attracting attention as a solution to the problems of greenhouse effect and air pollution caused by the concentration of carbon dioxide in the atmosphere by the exhaust gas from current internal combustion engines. However, the maximum speed of an electric vehicle is lower than that of an internal combustion engine vehicle, and the traveling distance per charge is not sufficient due to the problems of the efficiency of the electric motor, the electric capacity of the battery and the charging / discharging efficiency. Most of the loss in these efficiencies appears as heat generation,
The life of the electric motor and the overall efficiency of the electric vehicle are improved depending on how the generated heat is cooled or effectively utilized. Therefore, conventionally, the electric motor of the electric vehicle, the drive circuit unit of the electric motor, and the battery are individually installed, or at least two or more of them are installed in the refrigeration cycle of the air conditioner of the vehicle to perform air conditioning in the vehicle interior as usual and to sufficiently maintain each part The cooling method was used to effectively utilize the heat generated from each of these parts in the operation of the refrigeration cycle.

[0003]

However, the vehicle interior,
Since there are optimum temperatures for cooling the electric motor, the drive circuit, and the battery, it is necessary to set the evaporation temperature of the refrigerant, that is, the evaporation pressure to different values. For example, when the evaporating pressure of the heat exchanger for cooling the vehicle interior is lower than the evaporating pressure of the electric motor side, the flow rate of each refrigerant often changes greatly under the influence of heat load fluctuations. When refrigerants having different pressures, temperatures and flow rates are mixed in the accumulators provided on the suction side, the pressure in the accumulators also fluctuates greatly.
However, in this case, if the pressure in the accumulator is higher than the suction pressure of the compressor, by placing a capillary or pressure control valve in front of the refrigerant suction port of the compressor, the refrigeration cycle Stable operation becomes possible. However, when the pressure in the accumulator is lower than the suction pressure, the pressure in the accumulator becomes the suction pressure, so the compression ratio increases and the compressor efficiency increases rapidly due to a decrease in volumetric efficiency and refrigerant flow rate or a decrease in compression load. As a result, the refrigeration cycle becomes unstable. As a result, the efficiency of the entire cooling system is reduced due to the reduction in refrigeration capacity and the increase in power consumption.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention is to solve this drawback. In an electric vehicle having an electric motor as a drive source and the electric motor installed in a refrigeration cycle of an air conditioner for a vehicle, This is achieved by introducing a compressed refrigerant gas of high temperature and high pressure into an accumulator arranged on the low pressure side of the.

[0005]

The cooling cycle of the electric vehicle of the present invention will be described with reference to FIG.

When the vehicle interior air conditioner is in a cooling operation, the high temperature and high pressure refrigerant gas compressed by the compressor 1 is sent to the oil separator 2, where the refrigerant gas and the oil are separated, and the oil is the capillary tube 13. It is returned to the compressor 1 via. On the other hand, the refrigerant gas is sent to the vehicle exterior heat exchanger 4 via the four-way valve 3 to be cooled. The low-temperature and high-pressure liquid refrigerant after cooling passes through the check valve 8a and the heat exchanger 5 in the vehicle interior
Is sent to both directions of the electric motor 6. The refrigerant sent in the direction of the vehicle interior heat exchanger 5 is decompressed by the expansion valve 7b, cools the heat load in the vehicle interior in the vehicle interior heat exchanger 5, and the evaporated refrigerant is sent to the accumulator 10 through the four-way valve 3. To be On the other hand, the refrigerant sent in the direction of the electric motor 6 is decompressed by the expansion valve 7b whose pressure setting value is different from that of the expansion valve 7a to become a low-temperature low-pressure refrigerant, which cools the electric motor 6, and the evaporated refrigerant is the accumulator
Sent to. If the pressure of the refrigerant sent from the accumulator 10 from both directions is mixed and the pressure is higher than the suction pressure, the accumulator 10
The suction pressure adjusting valve 11 disposed downstream of the compressor 1 reduces the pressure and the refrigerant is sucked into the compressor 1 in a stable pressure state. On the other hand, when the pressure in the accumulator 10 is lower than the suction pressure, the suction pressure adjustment valve 11 alone cannot adjust the pressure. Therefore, the pressure in the accumulator 10 is constantly measured by the pressure sensor 12, and when the pressure value becomes lower than the suction pressure, the solenoid valve 9b on the bypass 14 is opened to introduce a part of the high temperature and high pressure refrigerant gas into the accumulator 10. To do. Here, the bypass passage 14 has an inner diameter (for example, a capillary tube) that does not significantly affect the decrease in the condensation pressure. By mixing with the high-pressure refrigerant gas, the pressure in the accumulator 10 rises, and due to the temperature rise, a part of the liquid refrigerant accumulated in the accumulator 10 evaporates and the pressure in the accumulator 10 further rises. In this way, when the pressure in the accumulator 10 becomes higher than the suction pressure, the solenoid valve 9b is closed and the introduction of the refrigerant gas is stopped. Then, until the pressure inside the accumulator 10 falls below the suction pressure again, the suction pressure adjusting valve 11 performs the compression of the refrigerant in a stable pressure state. Solenoid valve 9
The pressure set values for opening and closing b are respectively higher than the predetermined suction pressure and suction pressure to some extent (for example, suction pressure 0.4M).
O for Pa. 5 MPa) value, the solenoid valve 9b
It is possible to reduce the frequency of opening and closing, and to prevent hunting of the discharge pressure and damage to the solenoid valve 9b.

When the vehicle interior air conditioner is in heating operation, the compressed high-temperature and high-pressure refrigerant gas is separated from the refrigerant gas and oil in the oil separator 2 as in the cooling operation, and the oil is returned to the compressor 1. . The refrigerant gas is sent to the vehicle interior heat exchanger 5 via the four-way valve 3 to heat the vehicle interior by heat exchange with the air in the vehicle interior, while the refrigerant gas is cooled.
The cooled low-temperature high-pressure liquid refrigerant is sent to both the vehicle exterior heat exchanger 4 and the electric motor 6. The refrigerant sent to the exterior heat exchanger 4 is decompressed by the expansion valve 7c and exterior heat exchanger 4
Is evaporated by heat exchange with the outside air and is sent to the accumulator 10 through the four-way valve 3. On the other hand, the refrigerant sent in the direction of the electric motor 6 cools the electric motor 6 as in the cooling operation, and the evaporated refrigerant is sent to the accumulator 10 and the accumulator 10
The operation after adjusting the internal pressure is exactly the same as during the cooling operation.

By configuring the cooling system including the bypass passage for the high-temperature and high-pressure refrigerant gas as described above, the refrigerants that are individually cooled at different evaporating pressures and then mixed by the accumulator and sucked into the compressor are It is possible to eliminate the pressure drop and easily maintain stable operation of the refrigeration cycle under a predetermined pressure condition. Further, since the suction pressure can be stabilized only by introducing and mixing a part of the compressed gas on the discharge side in front of the compressor suction with a capillary tube or the like, a cooling system can be configured very easily.

[0009]

INDUSTRIAL APPLICABILITY As described above, the present invention uses an electric motor as a drive source, and in an electric vehicle in which the electric motor is installed in the refrigeration cycle of an automobile air conditioner, an accumulator arranged on the low pressure side in the refrigeration cycle. By introducing high-temperature and high-pressure compressed refrigerant gas, the pressure drop of the refrigerant sucked into the compressor after cooling individually at different evaporation pressures is eliminated, and stable refrigeration cycle operation under predetermined pressure conditions is achieved. Can be easily maintained, and the bypass passage can be configured by a capillary tube or the like, so that the cooling system can be easily configured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a cooling system for an electric vehicle according to the present invention.

[Explanation of symbols]

 1 compressor 2 oil separator 3 four-way valve 4 vehicle exterior heat exchanger 5 vehicle interior heat exchanger 6 electric motor 7a expansion valve 7b expansion valve 7c expansion valve 8a check valve 8b check valve 9a solenoid valve 9b solenoid valve 10 accumulator 11 intake Pressure control valve 12 Pressure sensor 13 Capillary tube 14 Bypass passage

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F25B 13/00 N 9335-3L Q 9335-3L

Claims (1)

[Claims] 1. An electric vehicle using an electric motor as a drive source, wherein the electric motor is installed in a refrigeration cycle of an automobile air conditioner, and a high-temperature high-pressure compressed refrigerant gas is stored in an accumulator arranged on the low-pressure side of the refrigeration cycle. A cooling system for electric vehicles characterized by being introduced.