JP6758506B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner including a refrigerant cooler for a control device.

Conventionally, there has been known a technique for cooling a control device, which is a heat generating member, using a refrigerant of a refrigerating cycle. For example, a cooler is provided in which a refrigerant having an intermediate pressure in the refrigeration cycle cools a heating device, electric expansion valves are arranged on the upstream side and the downstream side of the cooler, and the valve openings of both electric expansion valves are set. There is a technique of controlling the intermediate pressure by controlling it to control the amount of cooling from the heat generating device (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 11-23801

In cooling a control device using a refrigerant as in Patent Document 1, it is necessary to control the temperature of the refrigerant in order to suppress dew condensation and keep the temperature inside the control device above the ambient dew point temperature. However, since the temperature and pressure of the refrigerant flowing through the refrigeration cycle are different in each operation mode such as cooling operation and heating operation, it is necessary to control the refrigerant in each operation mode.
However, in the control as in Patent Document 1, the temperature of the refrigerant may be lower than the outside air temperature, especially during the heating operation, and the control device may be cooled to the dew point temperature or lower.

The present invention has been made to solve the above-mentioned problems, and is an air conditioner provided with a refrigerant cooler capable of suppressing dew condensation due to cooling of a control device using a refrigerant in each operation mode. The purpose is to provide.

The air conditioner in the present invention constitutes a refrigerant circuit in which a compressor, a heat source side heat exchanger, an electronic expansion valve for intermediate pressure adjustment, a load side electronic expansion valve, and a load side heat exchanger are connected by a refrigerant pipe. A flow path switching device provided on the discharge side of the compressor to switch the circulation direction of the refrigerant, a control device for controlling each device constituting the refrigerant circuit, an electronic expansion valve for adjusting the intermediate pressure, and an electronic expansion on the load side. A refrigerant cooler provided between the valves to cool the control device using a refrigerant is provided. In the cooling operation mode, the opening degree of the intermediate pressure adjusting electronic expansion valve is maximized, and in the heating operation mode. When the temperature of the refrigerant flowing through the refrigerant cooler is equal to or lower than the dew point temperature, the opening degree of the intermediate pressure adjusting electronic expansion valve is reduced, and then the opening degree of the load-side electronic expansion valve is further increased.

According to the air conditioner of the present invention, dew condensation due to cooling of the control device using the refrigerant can be suppressed in each operation mode.

It is a refrigerant circuit diagram of the air conditioner which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the refrigerating cycle in the cooling operation mode of the air conditioner which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the refrigerating cycle in the heating operation mode of the air conditioner which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram of the air conditioner which concerns on Embodiment 2 of this invention. It is a flowchart which shows the control of the bypass valve of the air conditioner which concerns on Embodiment 2 of this invention.

Hereinafter, the air conditioner according to the embodiment of the present invention will be described with reference to the drawings and the like. In each figure, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. In addition, the shape, size, arrangement, etc. of the configurations shown in each figure can be appropriately changed within the scope of the present invention.

Embodiment 1.
FIG. 1 is a refrigerant circuit diagram of the air conditioner according to the first embodiment of the present invention. The air conditioner 100 is installed in, for example, a building, an apartment, or the like, and can perform a cooling operation, a heating operation, and a defrosting operation by using a refrigerating cycle (heat pump cycle) for circulating a refrigerant. The air conditioner 100 has a heat source side unit 80 and a load side unit 90, and a refrigeration cycle is formed by connecting the heat source side unit 80 and the load side unit 90 with a refrigerant pipe 70.

Refrigerants include Freon refrigerants (for example, HFC-based refrigerants R32, R125, and R134a, and mixed refrigerants such as R410A, R407c, and R404A) and HFO refrigerants (for example, HFO-1234yf, HFO-1234ze (E), and HFO-1234ze). (Z)) is used. In addition, as the refrigerant, it is used for a steam compression type heat pump such as a CO2 refrigerant, an HC refrigerant (for example, propane, isobutane refrigerant), an ammonia refrigerant, and a mixed refrigerant of the above-mentioned refrigerant such as a mixed refrigerant of R32 and HFO-1234yf. Refrigerant is used.

First, the refrigeration cycle according to the first embodiment of the present invention will be described. The air conditioner 100 includes a compressor 1, a four-way valve 2, a heat source side heat exchanger 3, an intermediate pressure adjusting electronic expansion valve 4, a refrigerant cooler 5, a load side electronic expansion valve 6, a load side heat exchanger 7, and an accumulator. 8 is connected by a refrigerant pipe 70, and includes a refrigerant circuit in which the refrigerant circulates inside.

The heat source side unit 80 has a function of supplying cold heat or hot heat to the load side unit 90. The heat source side unit 80 includes a compressor 1, a four-way valve 2, a heat source side heat exchanger 3, an electronic expansion valve 4 for intermediate pressure adjustment, a refrigerant cooler 5, and an accumulator 8. These devices are connected in series to form part of the main refrigerant circuit.

The compressor 1 is a fluid machine that compresses the sucked low-pressure refrigerant and discharges it as the high-pressure refrigerant. The compressor 1 is configured as, for example, a rotary compressor or a scroll compressor. The compressor 1 may be configured as a compressor having a constant rotation frequency, or may be configured as a compressor equipped with an inverter and capable of controlling the rotation frequency.

The four-way valve 2 is provided on the discharge side of the compressor 1 and is a flow path switching device for switching the circulation direction of the refrigerant in the cooling operation mode and the circulation direction of the refrigerant in the heating operation mode. The flow of the refrigerant in the cooling operation mode and the heating operation mode will be described later.

The heat source side heat exchanger 3 is an air-cooled heat exchanger capable of exchanging heat between the refrigerant flowing inside and air. The heat source side heat exchanger 3 functions as a condenser in the cooling operation mode and as an evaporator in the heating operation mode. The load-side heat exchanger 3 is configured as, for example, a cross-fin type fin-and-tube heat exchanger composed of a heat transfer tube and a plurality of fins, or a plate fin type heat exchanger.

If the heat source side heat exchanger 3 is an air-cooled heat exchanger as in the first embodiment, the heat source side unit 80 takes in the air that exchanges heat with the heat source side heat exchanger 3 into the heat source side unit 80. Therefore, it has a heat source side blower 18. The rotation speed of the heat source side blower 18 is controlled by a control device 10 described later, and the condensing capacity or evaporation capacity of the heat source side heat exchanger 3 is controlled. The heat source side blower 18 is configured as, for example, a centrifugal fan such as a sirocco fan or a turbo fan, a cross flow fan, a mixed flow fan, or a propeller fan.

The electronic expansion valve 4 for adjusting the intermediate pressure has a function as a pressure reducing valve or an expansion valve, and decompresses and expands the refrigerant. The intermediate pressure adjusting electronic expansion valve 4 is configured as, for example, a pressure reducing device such as a linear electronic expansion valve capable of adjusting the opening degree in multiple stages or continuously.

The refrigerant cooler 5 is composed of a cooling pipe 51 and a cooling plate 52, which are a part of a refrigerant pipe between the intermediate pressure adjusting electronic expansion valve 4 and the load-side electronic expansion valve 6 described later. The refrigerant cooler 5 uses a refrigerant to absorb heat generated by the control device 10 described later, and cools the control device 10. Specifically, the cooling plate 52 is fixed in contact with the surface of the control device 10, and the cooling pipe 51 is fixed on the surface of the cooling plate 52 opposite to the surface in contact with the control device 10. Then, a refrigerant is allowed to flow inside the cooling pipe 51, and the heat generated by the control device 10 is absorbed through the cooling plate 52 to cool the control device 10. The cooling pipe 51 and the cooling plate 52 are preferably made of the same material, and for example, aluminum is used. Depending on the operating condition, the cooling pipe 51 may be lower than the outside air temperature, and dew condensation water may be generated on the surface. At this time, if the cooling pipe 51 and the cooling plate 52 are made of different materials, electrolytic corrosion is likely to occur. Therefore, by using the same material, electrolytic corrosion can be prevented. Further, the cooling pipe 51 and the cooling plate 52 may be closely fixed via silicon, or may be welded and fixed by brazing.

The accumulator 8 is provided on the suction side of the compressor 1 and has a function of separating the liquid refrigerant and the gas refrigerant and a function of storing excess refrigerant.

Further, the heat source side unit 80 has a high pressure sensor 11 that detects the pressure (high pressure) of the refrigerant discharged from the compressor 1. Further, the heat source side unit 80 has a low pressure pressure sensor 12 that detects the pressure (low pressure) of the refrigerant sucked into the compressor 1. The heat source side unit 100 further has a cooling pipe temperature sensor 13 that detects the pipe temperature of the refrigerant pipe upstream of the refrigerant cooler 5 in the heating operation mode. The heat source side unit 100 further has an outside air temperature sensor 14 for detecting the outside air temperature. Each of these sensors sends a signal related to the detected pressure and a signal related to the detected temperature to the control device 10 that controls the operation of the air conditioner 100.

The load side unit 90 supplies cold heat or heat from the heat source side unit 80 to the cooling load or the heating load. The load-side electronic expansion valve 6 and the load-side heat exchanger 7 are connected and mounted in series on the load-side unit 90, and together with the heat source-side unit 80, form a refrigerant circuit.

The load-side electronic expansion valve 6 has a function as a pressure reducing valve or an expansion valve, and reduces the pressure of the refrigerant to expand it. The load-side electronic expansion valve 6 is configured as a pressure reducing device such as a linear electronic expansion valve whose opening degree can be adjusted in multiple stages or continuously.

The load-side heat exchanger 7 is an air-cooled heat exchanger capable of exchanging heat between the refrigerant flowing inside and air. The load side heat exchanger 7 functions as an evaporator in the cooling operation mode and as a condenser in the heating operation mode. The load-side heat exchanger 3 is configured as, for example, a cross-fin type fin-and-tube heat exchanger composed of a heat transfer tube and a plurality of fins, or a plate fin type heat exchanger.

If the load-side heat exchanger 7 is an air-cooled heat exchanger as in the first embodiment, the load-side unit 90 takes in air that exchanges heat with the load-side heat exchanger 7 into the heat source-side unit 90. Therefore, it has a load side blower 19. The rotation speed of the load-side blower 19 is controlled by a control device 10 described later, and the condensing capacity or evaporation capacity of the load-side heat exchanger 7 is controlled. The load side blower 19 is configured as, for example, a centrifugal fan such as a sirocco fan or a turbo fan, a cross flow fan, a mixed flow fan, or a propeller fan.

Further, the load side unit 90 has a load side pipe temperature sensor 15 that detects the temperature of the refrigerant pipe between the load side electronic expansion valve 6 and the load side heat exchanger 7. The load-side piping temperature sensor 15 sends a signal related to the detected temperature to the control device 10 that controls the operation of the air conditioner 100.

The control device 10 operates the air conditioner 100 by using the control program installed in advance based on the information and the operation information from various other sensors mounted on the air conditioner 100 and the setting information of the user. It controls. The control device 10 controls, for example, the drive frequency control of the compressor 1, the switching control of the four-way valve 2, the opening degree control of each electronic expansion valve, the rotation speed control of each blower, and the like. Further, the control device 10 calculates the temperature of the refrigerant flowing into the refrigerant cooler 5 in the heating operation mode based on the pipe temperature information from the cooling pipe temperature sensor 13. The control device 10 is composed of, for example, hardware such as a circuit device that realizes such a function, or software executed on an arithmetic unit such as a microcomputer or a CPU.

In the first embodiment, the case where the control device 10 for controlling the operation of the air conditioner 100 is mounted on the heat source side unit 80 is shown as an example, but the load side unit 90 may be provided. Further, the control device 10 may be provided outside the heat source side unit 80 and the load side unit 90. Further, the control device 10 may be divided into a plurality of units according to the function and provided in each of the heat source side unit 80 and the load side unit 90. In this case, it is preferable to connect each control device wirelessly or by wire so that communication is possible.

Next, the operation of the refrigerant circuit of the air conditioner 100 will be described with reference to FIGS. 2 and 3. The air conditioner 100 receives requests for cooling operation, heating operation, and the like from, for example, a remote controller installed indoors or the like. FIG. 2 is a refrigerant circuit diagram showing a refrigeration cycle in the cooling operation mode of the air conditioner according to the embodiment of the present invention. FIG. 3 is a refrigerant circuit diagram showing a refrigeration cycle in the heating operation mode of the air conditioner according to the embodiment of the present invention. The circulation direction of the refrigerant in the cooling operation mode and the heating operation mode can be switched by the four-way valve 2.

First, the operation in the cooling operation mode will be described with reference to FIG. When the compressor 1 is driven in the cooling operation mode, the high-temperature and high-pressure gas refrigerant is discharged from the compressor 1 and flows into the heat source side heat exchanger 3 via the four-way valve 2. The refrigerant flowing into the heat source side heat exchanger 3 exchanges heat with air and is condensed to become a low-temperature and high-pressure refrigerant. The condensed refrigerant passes through the intermediate pressure adjusting electronic expansion valve 4 and then flows into the refrigerant cooler 5 to cool the control device 10. After that, it flows out from the heat source side unit 80, flows into the load side unit 90, is depressurized by the load side electronic expansion valve 6, and becomes a gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant exchanges heat with air in the load side heat exchanger 7 and evaporates. The evaporated refrigerant flows out from the load side unit 90, flows into the heat source side unit 80, is sucked into the compressor 1 through the four-way valve 2, and is compressed again. As described above, in the cooling operation mode, the load side heat exchanger 7 functions as an evaporator to cool the room.

In the cooling operation mode, the opening degree of the intermediate pressure adjusting electronic expansion valve 4 is controlled to the maximum in order to minimize the pressure loss. By doing so, the refrigerant condensed by the heat source side heat exchanger 3 is not depressurized and can flow into the refrigerant cooler 5 while maintaining the temperature equal to or higher than the outside air temperature, so that dew condensation occurs in the control device 10. It can be suppressed. Further, even if the opening degree of the intermediate pressure adjusting electronic expansion valve 4 is maximized, the load side electronic expansion valve 6 can reduce the pressure to the target evaporation temperature, so that the air conditioning capacity in the cooling operation mode is not insufficient. The maximum mentioned here includes the vicinity of the maximum.

Next, the operation in the heating operation mode will be described with reference to FIG. When the compressor 1 is driven in the heating operation mode, a high-temperature and high-pressure gas refrigerant is discharged from the compressor 1, flows out from the heat source side unit 80 via the four-way valve 2, flows into the load side unit 90, and loads. It flows into the side heat exchanger 7. The refrigerant flowing into the load-side heat exchanger 7 exchanges heat with air and is condensed to become a low-temperature and high-pressure refrigerant. The condensed refrigerant is depressurized by the load-side electronic expansion valve 6, becomes a gas-liquid two-phase refrigerant, flows out from the load-side unit 90, and flows into the heat source-side unit 80. The refrigerant that has flowed into the heat source side unit 80 flows into the refrigerant cooler 5, and cools the control device 10. After that, the pressure is reduced by the electronic expansion valve 4 for adjusting the intermediate pressure, and the pressure flows into the heat exchanger 3 on the heat source side. The refrigerant flowing into the heat source side heat exchanger 3 exchanges heat with air and evaporates. The evaporated refrigerant is sucked into the compressor 1 via the four-way valve 2 and compressed again. As described above, in the heating operation mode, the load side heat exchanger 7 functions as a condenser to heat the room.

In the heating operation mode, the refrigerant flowing into the refrigerant cooler 5 has passed through the load-side electronic expansion valve 6, so if the opening degree of the load-side electronic expansion valve 6 is small, it becomes a low-pressure low-temperature refrigerant and is controlled. Condensation may occur in the device 10. In order to suppress dew condensation, it is necessary to set the temperature of the refrigerant flowing into the refrigerant cooler 5 to be equal to or higher than the dew point temperature. Therefore, when the temperature of the refrigerant detected by the cooling pipe temperature sensor 13 is equal to or lower than the dew point temperature, the opening degree of the electronic expansion valve 4 for adjusting the intermediate pressure is reduced to reduce the opening degree of the gas-liquid two flowing into the refrigerant cooler 5. The pressure of the phase refrigerant can be increased to raise the temperature.

If the temperature of the refrigerant flowing into the refrigerant cooler 5 cannot be made higher than the dew point temperature only by controlling the electronic expansion valve 4 for adjusting the intermediate pressure, the opening degree of the load-side electronic expansion valve 6 is further increased to cool the refrigerant. The pressure of the refrigerant flowing into the vessel 5 can be further increased, and the temperature of the refrigerant can be further increased.

According to the first embodiment configured as described above, the refrigerant condensed by the heat source side heat exchanger 3 is controlled by maximally controlling the opening degree of the intermediate pressure adjusting electronic expansion valve 4 in the cooling operation mode. Is not depressurized and can flow into the refrigerant cooler 5 while maintaining a temperature equal to or higher than the outside air temperature, so that dew condensation in the control device 10 can be suppressed.
Further, by reducing the opening degree of the intermediate pressure adjusting electronic expansion valve 4 in the heating operation mode, the temperature of the refrigerant flowing into the refrigerant cooler 5 can be raised, and dew condensation can be suppressed. Further, by increasing the opening degree of the load-side electronic expansion valve 6, the temperature of the refrigerant can be further raised, so that the temperature of the refrigerant flowing into the refrigerant cooler 5 can be more reliably raised than the dew point temperature. it can.

Embodiment 2.
The air conditioner according to the second embodiment of the present invention will be described. FIG. 4 is a refrigerant circuit diagram of the air conditioner according to the second embodiment of the present invention. In FIG. 4, those having the same reference numerals as those in FIG. 1 indicate the same or corresponding configurations, and the description thereof will be omitted.

The air conditioner 101 according to the second embodiment of the present invention is a bypass circuit 21 branched from the refrigerant pipe on the discharge side of the compressor 1 and connected to the refrigerant pipe between the refrigerant cooler 5 and the electronic expansion valve 6 on the load side. It is different from the air conditioner 100 of the first embodiment in that it includes a bypass valve 20 provided in the bypass circuit 21.

Specifically, even if the temperature of the refrigerant flowing into the refrigerant cooler 5 is equal to or lower than the dew point temperature, the opening degree of the electronic expansion valve 4 for adjusting the intermediate pressure cannot be reduced because the low pressure is extremely low. In some cases. If the opening degree of the electronic expansion valve 4 for adjusting the intermediate pressure is reduced, the suction density of the compressor 1 is reduced, the circulation flow rate is reduced, the heating and air conditioning capacity is reduced, and it takes time to start the heating operation. is there. Such a phenomenon is likely to occur when the pressure and temperature states of the refrigerant are unstable, and particularly during a transient operation such as when the heating operation is started or when the defrosting operation is completed.

Therefore, in order to prevent the temperature of the refrigerant flowing into the refrigerant cooler 5 from temporarily dropping, the refrigerant pipe is branched from the discharge side refrigerant pipe of the compressor 1 to the refrigerant pipe between the refrigerant cooler 5 and the load side electronic expansion valve 6. A bypass circuit 21 to be connected is provided. Further, a bypass valve 20 is provided on the bypass circuit 21 in order to adjust the flow rate of the refrigerant flowing through the bypass circuit 21. The bypass valve 20 is configured as, for example, a pressure reducing device such as a linear electronic expansion valve whose opening degree can be adjusted in multiple stages or continuously. It may also be configured as a capillary tube.

The bypass circuit 21 can join the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 with the refrigerant flowing into the refrigerant cooler 5. Therefore, the temperature of the refrigerant flowing into the refrigerant cooler 5 can be raised.

FIG. 5 is a flowchart showing the control of the bypass valve of the air conditioner according to the second embodiment of the present invention. At the first time, since the bypass valve 20 is in the closed state, no refrigerant is flowing through the bypass circuit 21. First, the control device 10 determines whether the temperature of the refrigerant detected by the cooling pipe temperature sensor 13 is higher than the dew point temperature (ST1). When the temperature of the refrigerant is higher than the dew point temperature, there is a low possibility of dew condensation in the control device 10, so nothing is done.

When the temperature of the refrigerant is equal to or lower than the dew point temperature, it is determined whether the low pressure pressure detected by the low pressure pressure sensor 12 is higher than a predetermined value determined in advance (ST2). When the low pressure is higher than the predetermined value, the suction density of the compressor 1 is large to some extent, so that the opening degree of the electronic expansion valve 4 for adjusting the intermediate pressure can be reduced (ST6).

When the low pressure is equal to or less than a predetermined value, the suction density of the compressor 1 is reduced and the circulating flow rate is reduced, so that the opening degree of the electronic expansion valve 4 for adjusting the intermediate pressure cannot be reduced. Therefore, the bypass valve 20 is opened and the refrigerant flows through the bypass circuit 21 (ST3). By doing so, the temperature of the refrigerant flowing into the refrigerant cooler 5 can be raised.

After that, the control device 10 determines whether the temperature of the refrigerant detected by the cooling pipe temperature sensor 13 is higher than the dew point temperature and the degree of supercooling at the outlet of the indoor unit is higher than a predetermined value (predetermined value). ST4). If any of the conditions is not met, the bypass valve 20 is left open. When any of the conditions is satisfied, the bypass valve 20 is closed (ST5). Here, the degree of supercooling at the outlet of the load side unit 90 is set as a condition for closing the bypass valve 20 in order to confirm that the degree of dryness of the refrigerant flowing into the refrigerant cooler 5 is small. is there. When the degree of dryness is large, even if the electronic expansion valve 4 for adjusting the intermediate pressure is closed, the pressure of the refrigerant flowing into the refrigerant cooler 5 is difficult to increase, and when the bypass valve 20 is closed, the pressure temporarily decreases again. There is a high possibility that it will end up. Therefore, it is controlled to close the bypass valve 20 after confirming that the degree of supercooling at the outlet of the load side unit 90 has reached a predetermined value and determining that the pressure of the refrigerant flowing through the refrigerant cooler 5 has risen sufficiently. .. After closing the bypass valve 20, the system returns to ST1 again to determine whether the temperature of the refrigerant is higher than the dew point temperature.

The degree of supercooling at the outlet of the load-side unit 90 is calculated by subtracting the condenser outlet temperature measured by the load-side piping temperature sensor 15 from the condensation temperature obtained by the high-pressure pressure sensor 11.

According to the second embodiment configured as described above, a bypass circuit is branched from the refrigerant pipe on the discharge side of the compressor 1 and connected to the refrigerant pipe between the refrigerant cooler 5 and the load side electronic expansion valve 6. By providing 21, the bypass valve 20 is opened to open the refrigerant cooler when the temperature of the refrigerant flowing into the refrigerant cooler 53 is equal to or lower than the dew point temperature and the low pressure is equal to or lower than a predetermined value. It is possible to prevent a decrease in the temperature of the refrigerant flowing in No. 5 and suppress dew condensation in the control device 10.

Further, the temperature of the refrigerant detected by the cooling pipe temperature sensor 13 becomes higher than the dew point temperature, and the degree of supercooling at the outlet of the load side unit 90 becomes larger than a predetermined value predetermined, so that the bypass valve 20 is operated. By closing it, it is possible to prevent the refrigerant temperature from dropping more reliably.

Although the present invention has been described above using the above-described embodiment, the technical scope of the present invention is not limited to the scope described in the above-described embodiment. Various changes or improvements can be made to each of the above embodiments without departing from the gist of the invention, and the modified or improved forms are also included in the technical scope of the present invention.

For example, in the present embodiment, in order to suppress dew condensation in the control device 10, the temperature of the refrigerant flowing into the refrigerant cooler 5 is controlled to be equal to or higher than the dew point temperature, but when the dew point temperature is unknown, The temperature of the refrigerant flowing into the refrigerant cooler 5 may be controlled to be equal to or higher than the value obtained by subtracting α degree from the outside air temperature detected by the outside air temperature sensor 14. The temperature inside the control device 10 which is a heat generating member is cooled by the refrigerant flowing into the refrigerant cooler 5, but it is necessary to be equal to or higher than the dew point temperature in order to suppress dew condensation. Therefore, the degree to which the inside of the control device 10 is cooled is calculated in advance from the heat capacity of the cooling plate 52, and the temperature α at which there is no problem even if the temperature of the refrigerant flowing into the refrigerant cooler 5 is lower than the outside air temperature is calculated.

1 Compressor, 2 4-way valve, 3 Heat source side heat exchanger, 4 Intermediate pressure adjustment electronic expansion valve, 5 Refrigerant cooler, 6 Load side electronic expansion valve, 7 Load side heat exchanger, 8 Accumulator, 10 Controller, 11 High pressure pressure sensor, 12 Low pressure pressure sensor, 13 Cooling pipe temperature sensor, 14 Outside air temperature sensor, 15 Load side pipe temperature sensor, 18 Heat source side blower, 19 Load side blower, 20 Bypass valve, 21 Bypass circuit, 51 Cooling pipe, 52 Cooling plate, 70 Refrigerant piping, 80 Heat source side unit, 90 Load side unit, 100 Air conditioner

Claims (5)

A compressor, a heat source side heat exchanger, an electronic expansion valve for intermediate pressure adjustment, a load side electronic expansion valve, and a load side heat exchanger are connected by a refrigerant pipe to form a refrigerant circuit.
A flow path switching device provided on the discharge side of the compressor to switch the circulation direction of the refrigerant, and
A control device that controls each device that constitutes the refrigerant circuit, and
A refrigerant cooler provided between the intermediate pressure adjusting electronic expansion valve and the load-side electronic expansion valve to cool the control device using a refrigerant is provided.
In the cooling operation mode, the opening degree of the electronic expansion valve for adjusting the intermediate pressure is maximized .
In the heating operation mode, when the temperature of the refrigerant flowing through the refrigerant cooler is equal to or lower than the dew point temperature, the opening degree of the intermediate pressure adjusting electronic expansion valve is reduced, and then the opening degree of the load side electronic expansion valve is further increased. Enlarge,
Air conditioner. A bypass circuit branched from the refrigerant pipe on the discharge side of the compressor and connected to the refrigerant pipe between the refrigerant cooler and the load side electronic expansion valve.
Air conditioner according to claim 1; and a bypass valve provided in the bypass circuit. The air conditioner according to claim 2 , wherein the bypass valve is opened when the temperature of the refrigerant flowing through the refrigerant cooler is equal to or lower than the dew point temperature and the pressure of the refrigerant sucked into the compressor is equal to or lower than a predetermined value. The temperature of the refrigerant flowing through the refrigerant condenser dew point temperature or less, and, when the pressure of the refrigerant sucked into the compressor is higher than a predetermined value, claim to reduce the opening of the intermediate pressure adjusting electronic expansion valve 2 Or the air conditioner according to claim 3 . The refrigerant cooler includes a part of a refrigerant pipe between the intermediate pressure adjusting electronic expansion valve and the load-side electronic expansion valve, and a cooling plate fixed in contact with the control device.
The air conditioner according to any one of claims 1 to 4 , wherein a part of the refrigerant pipe is fixed to a surface of the cooling plate opposite to the surface in contact with the control device.

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