JP7069415B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner capable of performing both compression and pump cycles.

Conventionally, an air conditioner having a combined cycle capable of executing both a compression refrigeration cycle (hereinafter referred to as "compression cycle") and a refrigerant pump cycle (hereinafter referred to as "pump cycle") has been known. ing. In an air conditioner having such a composite cycle, when the pump cycle is executed, the refrigerant circulates so that the liquid refrigerant is sucked into the refrigerant pump in order to prevent damage to the refrigerant pump due to idle operation. It is judged whether or not it is. For example, in Patent Document 1, a pressure sensor and a temperature sensor are provided on the suction side of the refrigerant pump, and the refrigerant circulation is based on the degree of supercooling obtained based on the pressure detected by the pressure sensor and the temperature detected by the temperature sensor. An air conditioner for confirming the presence or absence of is disclosed.

Japanese Patent No. 5506620

However, in the air conditioner described in Patent Document 1, the presence or absence of refrigerant circulation can be confirmed only by the degree of supercooling. Therefore, if a problem occurs in the sensor provided on the suction side of the pump, it becomes impossible to confirm the presence or absence of circulation of the refrigerant.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an air conditioner capable of confirming the presence or absence of refrigerant circulation when a pump cycle is being executed.

The air conditioner according to the present invention is an air conditioner in which a refrigerant pump, an expansion valve, an evaporator and a condenser are connected by a pipe to form a pump cycle in which the refrigerant circulates, and the operation is performed by the pump cycle. The evaporator outlet pressure sensor that detects the evaporator outlet pressure of the refrigerant flowing out of the evaporator, the evaporator inlet temperature sensor that detects the evaporator inlet temperature of the refrigerant flowing into the evaporator, and the evaporation. It is provided with a control device for determining the presence or absence of refrigerant circulation based on the degree of superheat on the refrigerant inflow side of the evaporator obtained from the vessel outlet pressure and the evaporator inlet temperature.

In the air conditioner according to the present invention, the presence or absence of refrigerant circulation can be determined from the degree of superheat on the refrigerant inflow side of the evaporator obtained from the evaporator outlet pressure and the evaporator inlet temperature.

It is a refrigerant circuit diagram which shows an example of the structure of the air conditioner which concerns on Embodiment 1. FIG. It is a functional block diagram which shows an example of the structure of the control device of FIG. It is a hardware block diagram which shows an example of the structure of the control device of FIG. It is a hardware configuration diagram which shows the other example of the configuration of the control device of FIG. It is a flowchart which shows an example of the flow of the refrigerant circulation confirmation processing by the air conditioner which concerns on Embodiment 1. FIG. It is a refrigerant circuit diagram which shows an example of the structure of the air conditioner which concerns on Embodiment 2. FIG. It is a functional block diagram which shows an example of the structure of the control device of FIG. It is a flowchart which shows an example of the flow of the refrigerant circulation confirmation processing by the air conditioner which concerns on Embodiment 2. FIG.

Embodiment 1.
Hereinafter, the air conditioner according to the first embodiment will be described. The air conditioner according to the first embodiment can switch between a compression cycle in which a compressor is used to circulate the refrigerant and a pump cycle in which the refrigerant is circulated using a refrigerant pump. Is.

[Structure of air conditioner 100]
FIG. 1 is a refrigerant circuit diagram showing an example of the configuration of the air conditioner 100 according to the first embodiment. As shown in FIG. 1, the air conditioner 100 is formed with a refrigerant circulation circuit 101 in which a refrigerant circulates inside. The refrigerant circulation circuit 101 includes a compressor 1, a condenser 10, an expansion valve 2, an evaporator 3, a receiver 4, a refrigerant pump 5, and a supercooling heat exchanger 6.

The compressor 1 sucks in the low temperature and low pressure refrigerant, compresses the sucked refrigerant, and discharges the high temperature and high pressure refrigerant. As the compressor 1, for example, an inverter compressor or the like in which the capacity, which is the transmission amount per unit time, is controlled by changing the operating frequency is used. The operating frequency of the compressor 1 is controlled by the control device 50.

The condenser 10 exchanges heat between the refrigerant flowing through the refrigerant circulation circuit 101 and the outdoor air, dissipates the heat of the refrigerant to the outdoor air, and condenses the refrigerant. The refrigerant inflow side of the condenser 10 is connected to the discharge side of the compressor 1 by piping. Further, the refrigerant outflow side of the condenser 10 is connected to the inflow side of the receiver 4 by piping.

In the first embodiment, the condenser 10 includes a first condenser 11 and a second condenser 12. The first condenser 11 and the second condenser 12 are connected in parallel to the discharge side of the compressor 1. Therefore, the refrigerant outflow sides of the first condenser 11 and the second condenser 12 are connected in parallel to the inflow side of the receiver 4. That is, the first condenser 11 and the second condenser 12 are connected in parallel between the compressor 1 and the receiver 4. When the heat exchange load can be covered only by the first condenser 11, the condenser 10 may be composed of only the first condenser 11.

The refrigerant circulation circuit 101 includes a first pipe 21 and a second pipe 22. The first pipe 21 is a pipe that connects the refrigerant outflow side of the first condenser 11 and the inflow side of the receiver 4. Further, the second pipe 22 is a pipe in which one end is connected to the refrigerant outflow side of the second condenser 12 and the other end is connected to the first pipe 21. By providing the first pipe 21 and the second pipe 22, the refrigerant outflow side of the first condenser 11 and the refrigerant outflow side of the second condenser 12 are connected in parallel to the inflow side of the receiver 4. ..

The receiver 4 stores the liquid refrigerant that has flowed into the container, and adjusts the amount of excess refrigerant by raising and lowering the liquid level according to the amount of the liquid refrigerant that flows in and out. The receiver 4 is connected between the condenser 10 and the refrigerant pump 5. The outflow side of the receiver 4 is connected to the refrigerant inflow side of the supercooling heat exchanger 6 by piping.

The supercooling heat exchanger 6 is provided between the receiver 4 and the refrigerant pump 5 to further cool the liquid refrigerant flowing out from the receiver 4 to increase the degree of supercooling. By increasing the degree of supercooling of the liquid refrigerant, the cooling capacity of the air conditioner 100 is improved. In the refrigerant circulation circuit 101 according to the first embodiment, the end of the bypass pipe 20 described later on the outflow side is connected between the receiver 4 and the supercooling heat exchanger 6. Therefore, the liquid refrigerant flowing out of the bypass pipe 20 is also cooled by the supercooling heat exchanger 6 to increase the degree of supercooling. Therefore, the cooling capacity of the air conditioner 100 is further improved.

The refrigerant pump 5 is driven by a motor (not shown) to pressurize and deliver the liquid refrigerant flowing out of the receiver 4. The rotation speed of the refrigerant pump 5 is controlled by the control device 50. The refrigerant pump 5 is connected between the receiver 4 and the expansion valve 2. The inflow side of the refrigerant pump 5 is connected to the refrigerant outflow side of the supercooling heat exchanger 6 by piping. The discharge side of the refrigerant pump 5 is connected to the inflow side of the expansion valve 2 by piping.

The expansion valve 2 expands the refrigerant. The expansion valve 2 is composed of, for example, a valve such as an electronic expansion valve whose opening degree can be controlled, or a capillary tube. When the expansion valve 2 is a valve whose opening degree can be controlled, the opening degree of the expansion valve 2 is controlled by the control device 50. The inflow side of the expansion valve 2 is connected to the outflow side of the refrigerant pump 5 by piping. The outflow side of the expansion valve 2 is connected to the refrigerant inflow side of the evaporator 3 by piping.

The evaporator 3 exchanges heat between the refrigerant flowing through the refrigerant circulation circuit 101 and the indoor air supplied by a blower (not shown) and the refrigerant to evaporate the refrigerant. The refrigerant inflow side of the evaporator 3 is connected to the outflow side of the expansion valve 2. The refrigerant outflow side of the evaporator 3 is connected to the suction side of the compressor 1.

Further, the refrigerant circulation circuit 101 according to the first embodiment includes a bypass pipe 20. The end of the inflow side of the bypass pipe 20 is connected between the refrigerant outflow side of the condenser 10 and the inflow side of the receiver 4. Further, the end of the bypass pipe 20 on the outflow side is connected between the receiver 4 and the supercooled heat exchanger 6. By providing the bypass pipe 20 in the refrigerant circulation circuit 101, a part of the refrigerant flowing out from the condenser 10 can bypass the receiver 4 and flow to the suction side of the refrigerant pump 5.

As described above, the condenser 10 according to the first embodiment includes a first condenser 11 and a second condenser 12. Therefore, the inflow side end of the bypass pipe 20 is connected to the second pipe 22 that connects the refrigerant outflow side of the second condenser 12 and the first pipe 21. That is, all the refrigerant flowing out of the first condenser 11 flows to the refrigerant pump 5 through the receiver 4. On the other hand, a part of the refrigerant flowing out from the second condenser 12 flows to the refrigerant pump 5 through the receiver 4. Further, the remaining part of the refrigerant flowing out of the second condenser 12 bypasses the receiver 4 and flows to the refrigerant pump 5.

Further, the refrigerant circulation circuit 101 according to the first embodiment includes a bypass pipe 23 and a check valve 7. The bypass pipe 23 is connected between the suction side and the discharge side of the compressor 1 so that the refrigerant circulating in the refrigerant circulation circuit 101 can flow around the compressor 1.

The check valve 7 is provided in the bypass pipe 23. The check valve 7 regulates the flow of the refrigerant from the discharge side of the compressor 1 to the suction side of the compressor 1 in the bypass pipe 23. By providing the bypass pipe 23 and the check valve 7, the refrigerant flowing out of the evaporator 3 can flow around the stopped compressor 1 during the pump cycle in which the compressor 1 is stopped. Further, during the compression cycle in which the compressor 1 is driven, the check valve 7 can prevent the refrigerant discharged from the compressor 1 from flowing to the suction port side of the compressor 1 through the bypass pipe 23.

The configuration for bypassing the stopped compressor 1 is not limited to the bypass pipe 23 and the check valve 7. For example, as a configuration for bypassing the stopped compressor 1, the configuration used in the conventional combined cycle air conditioner may be appropriately adopted.

Furthermore, the refrigerant circulation circuit 101 according to the first embodiment includes a bypass pipe 24 and a check valve 8. The bypass pipe 24 is connected between the suction side and the discharge side of the refrigerant pump 5 so that the refrigerant circulating in the refrigerant circulation circuit 101 can flow around the refrigerant pump 5.

The check valve 8 is provided in the bypass pipe 24. The check valve 8 regulates the flow of the refrigerant from the discharge side of the refrigerant pump 5 to the suction side of the refrigerant pump 5 in the bypass pipe 24. By providing the bypass pipe 24 and the check valve 8, the refrigerant flowing out of the supercooling heat exchanger 6 may flow around the stopped refrigerant pump 5 during the compression cycle in which the refrigerant pump 5 is stopped. can. Further, during the pump cycle in which the refrigerant pump 5 is driven, the check valve 8 can prevent the refrigerant discharged from the refrigerant pump 5 from flowing to the suction port side of the refrigerant pump 5 through the bypass pipe 24.

The configuration for bypassing the stopped refrigerant pump 5 is not limited to the bypass pipe 24 and the check valve 8. For example, as a configuration for bypassing the stopped refrigerant pump 5, the configuration used in the conventional combined cycle air conditioner may be appropriately adopted.

In the air conditioner 100 configured in this way, at least the compressor 1, the condenser 10, the expansion valve 2 and the evaporator 3 are connected by pipes to form a compression cycle. Further, in the air conditioner 100, at least the refrigerant pump 5, the expansion valve 2, the evaporator 3 and the condenser 10 are connected by pipes to form a pump cycle.

Further, the refrigerant circulation circuit 101 according to the first embodiment is provided with a pump suction pressure sensor 41, a pump suction temperature sensor 42, an evaporator inlet temperature sensor 43, and an evaporator outlet pressure sensor 44.

The pump suction pressure sensor 41 is provided in a pipe on the suction side of the refrigerant pump 5. The pump suction pressure sensor 41 detects the pump suction pressure, which is the pressure of the refrigerant sucked into the refrigerant pump 5. The pump suction temperature sensor 42 is provided on the suction side of the refrigerant pump 5. The pump suction temperature sensor 42 detects the pump suction temperature, which is the temperature of the refrigerant sucked into the refrigerant pump 5.

The evaporator inlet temperature sensor 43 is provided on the refrigerant inflow side of the evaporator 3. The evaporator inlet temperature sensor 43 detects the evaporator inlet temperature, which is the temperature of the refrigerant flowing into the evaporator 3. The evaporator outlet pressure sensor 44 is provided in the piping on the refrigerant outflow side of the evaporator 3. The evaporator outlet pressure sensor 44 detects the evaporator outlet pressure, which is the pressure of the refrigerant flowing out of the evaporator 3.

The refrigerant circulation circuit 101 according to the first embodiment is provided with a check valve 31, an expansion valve 32, and an expansion valve 33, although it is not an essential configuration.

The check valve 31 is provided in the second pipe 22 that connects the outflow side of the second condenser 12 and the first pipe 21. The check valve 31 regulates the flow of the refrigerant from the outflow-side end of the second condenser 12 to the outflow-side end of the first pipe 21 in the second pipe 22. By providing the check valve 31, as will be described later, the retention of the liquid refrigerant in the second condenser 12 can be suppressed, and the cooling capacity of the air conditioner 100 can be improved.

The expansion valve 32 is composed of, for example, a valve such as an electronic expansion valve whose opening degree can be controlled, or a capillary tube. When the expansion valve 32 is a valve whose opening degree can be controlled, the opening degree of the expansion valve 32 is controlled by the control device 50. The expansion valve 32 is provided in a pipe connecting the discharge side of the compressor 1 and the refrigerant inflow side of the second condenser 12.

In this case, the pipe connected to the discharge port of the compressor 1 is branched in two directions on the way. Then, one of the branched pipes is connected to the inlet of the refrigerant of the second condenser 12. Further, the other end of the branched pipe is connected to the inlet of the refrigerant of the first condenser 11. The expansion valve 32 is provided in the branching pipe toward the pipe connected to the refrigerant inlet of the second condenser 12. By providing the expansion valve 32, the amount of the refrigerant flowing into the second condenser 12 can be adjusted.

The expansion valve 33 is composed of, for example, a valve such as an electronic expansion valve whose opening degree can be controlled, or a capillary tube. When the expansion valve 33 is a valve whose opening degree can be controlled, the opening degree of the expansion valve 33 is controlled by the control device 50. The expansion valve 33 is provided in the bypass pipe 20. By providing the expansion valve 33, the amount of the refrigerant flowing through the bypass pipe 20 can be adjusted.

Here, the air conditioner 100 according to the first embodiment includes the outdoor unit 110 and the indoor unit 120. Each configuration of the refrigerant circulation circuit 101 described above is housed in the outdoor unit 110 or the indoor unit 120. The outdoor unit 110 includes a receiver 4, a refrigerant pump 5, a supercooling heat exchanger 6, a check valve 8, a first condenser 11, a second condenser 12, a bypass pipe 20, a first pipe 21, and a second pipe 22. , Bypass pipe 24, check valve 31, expansion valve 32, expansion valve 33, pump suction pressure sensor 41 and pump suction temperature sensor 42 are accommodated. The indoor unit 120 includes a compressor 1, an expansion valve 2, an evaporator 3, a check valve 7, a bypass pipe 23, an evaporator inlet temperature sensor 43, and an evaporator outlet pressure sensor 44. The outdoor unit 110 is installed outdoors, for example. Further, the indoor unit 120 is installed, for example, in a room which is a space to be cooled. Further, the outdoor unit 110 is installed at a position higher than, for example, the indoor unit 120.

Further, the air conditioner 100 includes a control device 50. The control device 50 controls each part provided in the air conditioner 100. In particular, in the first embodiment, the control device 50 performs a refrigerant circulation confirmation process for confirming the presence or absence of refrigerant circulation in the refrigerant circulation circuit 101 during the pump cycle based on the detection results by various sensors.

FIG. 2 is a functional block diagram showing an example of the configuration of the control device 50 of FIG. As shown in FIG. 2, the control device 50 includes an information acquisition unit 51, a supercooling degree calculation unit 52, a superheat degree calculation unit 53, a comparison unit 54, an equipment control unit 55, and a storage unit 56. The control device 50 is composed of an arithmetic unit such as a microcomputer that realizes various functions by executing software, or hardware such as a circuit device corresponding to various functions.

The information acquisition unit 51 acquires sensor information detected by various sensors or the like provided in the air conditioner 100. In the first embodiment, the information acquisition unit 51 acquires the pump suction pressure as sensor information from the pump suction pressure sensor 41. The information acquisition unit 51 acquires the pump suction temperature as sensor information from the pump suction temperature sensor 42. The information acquisition unit 51 acquires the evaporator inlet temperature as sensor information from the evaporator inlet temperature sensor 43. The information acquisition unit 51 acquires the evaporator outlet pressure as sensor information from the evaporator outlet pressure sensor 44. Then, the information acquisition unit 51 supplies the acquired pump suction pressure and pump suction temperature to the supercooling degree calculation unit 52. Further, the information acquisition unit 51 supplies the acquired evaporator inlet temperature and evaporator outlet pressure to the superheat degree calculation unit 53.

The supercooling degree calculation unit 52 calculates the supercooling degree SC of the refrigerant sucked into the refrigerant pump 5 based on the pump suction pressure and the pump suction temperature acquired by the information acquisition unit 51. The degree of supercooling SC is calculated by subtracting the pump suction temperature from the saturated liquid temperature obtained from the pump suction pressure.

The superheat degree calculation unit 53 calculates the superheat degree SH on the refrigerant inflow side of the evaporator 3 based on the evaporator inlet temperature and the evaporator outlet pressure acquired by the information acquisition unit 51. The degree of superheat SH is calculated by subtracting the evaporator inlet temperature from the saturated gas temperature obtained from the evaporator outlet pressure.

The comparison unit 54 compares the supercooling degree SC calculated by the supercooling degree calculation unit 52 with the set supercooling degree SC _SET stored in the storage unit 56. Further, the comparison unit 54 compares the superheat degree SH calculated by the superheat degree calculation unit 53 with the set superheat degree SH _SET stored in the storage unit 56. The set supercooling degree SC _SET indicates a threshold value for the supercooling degree SC calculated by the supercooling degree calculation unit 52. The set superheat degree SH _SET indicates a threshold value for the superheat degree SH calculated by the superheat degree calculation unit 53.

The device control unit 55 controls each unit of the air conditioner 100 based on sensor information from various sensors provided in the air conditioner 100. In particular, in the first embodiment, the equipment control unit 55 controls the compressor 1 and the refrigerant pump 5 according to the comparison result of the comparison unit 54.

The storage unit 56 stores various values used in each unit of the control device 50. Specifically, the storage unit 56 stores the set supercooling degree SC _SET and the set superheat degree SH _SET used in the comparison unit 54.

FIG. 3 is a hardware configuration diagram showing an example of the configuration of the control device 50 of FIG. When various functions of the control device 50 are executed by hardware, the control device 50 of FIG. 2 is composed of a processing circuit 61 as shown in FIG. In the control device 50 of FIG. 2, each function of the information acquisition unit 51, the supercooling degree calculation unit 52, the superheat degree calculation unit 53, the comparison unit 54, the device control unit 55, and the storage unit 56 is realized by the processing circuit 61. ..

When each function is executed by hardware, the processing circuit 61 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate). Array) or a combination of these is applicable. The control device 50 may realize the functions of the information acquisition unit 51, the supercooling degree calculation unit 52, the superheat degree calculation unit 53, the comparison unit 54, the device control unit 55, and the storage unit 56 in the processing circuit 61. However, the functions of each part may be realized by one processing circuit 61.

FIG. 4 is a hardware configuration diagram showing another example of the configuration of the control device 50 of FIG. When various functions of the control device 50 are executed by software, the control device 50 of FIG. 2 is composed of a processor 71 and a memory 72 as shown in FIG. In the control device 50, the functions of the information acquisition unit 51, the supercooling degree calculation unit 52, the superheat degree calculation unit 53, the comparison unit 54, the device control unit 55, and the storage unit 56 are realized by the processor 71 and the memory 72.

When each function is executed by software, in the control device 50, the functions of the information acquisition unit 51, the supercooling degree calculation unit 52, the supercooling degree calculation unit 53, the comparison unit 54, the device control unit 55, and the storage unit 56 are software. , Firmware, or a combination of software and firmware. The software and firmware are written as a program and stored in the memory 72. The processor 71 realizes the functions of each part by reading and executing the program stored in the memory 72.

As the memory 72, for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable and Programmable ROM), EPROM (Electrically Erasable Memory, etc.) volatile semiconductor such as RAM (Electrically Erasable Memory) Is used. Further, as the memory 72, for example, a removable recording medium such as a magnetic disk, a flexible disk, an optical disk, a CD (Compact Disc), an MD (Mini Disc), and a DVD (Digital Versaille Disc) may be used.

[Operation of air conditioner 100]
Next, the operation of the air conditioner 100 will be described. The air conditioner 100 according to the first embodiment is a composite cycle type air conditioner capable of executing both a compression cycle and a pump cycle. That is, the air conditioner 100 can switch between the compression cycle and the pump cycle. The compression cycle is an operation in which the refrigerant circulates in the refrigerant circulation circuit 101 in a state where the compressor 1 is driven and the refrigerant pump 5 is stopped. Further, the pump cycle is an operation in which the refrigerant circulates in the refrigerant circulation circuit 101 in a state where the refrigerant pump 5 is driven and the compressor 1 is stopped, and is executed when the outside air temperature is lower than the room temperature.

(Flow of refrigerant during cooling operation by compression cycle)
The flow of the refrigerant during the cooling operation by the compression cycle will be described. The low-temperature low-pressure refrigerant is compressed by the compressor 1 and discharged as a high-temperature high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 10. The high-temperature and high-pressure gas refrigerant that has flowed into the condenser 10 exchanges heat with the outdoor air and condenses while radiating heat, becomes a high-pressure liquid refrigerant, and flows out of the condenser 10.

The high-pressure liquid refrigerant flowing out of the condenser 10 flows into the receiver 4, the amount of the refrigerant is adjusted, and the liquid refrigerant flows out from the receiver 4. The liquid refrigerant flowing out from the receiver 4 flows into the supercooling heat exchanger 6, and flows out from the supercooling heat exchanger 6 in a state where the degree of supercooling is increased by further cooling. Since the refrigerant pump 5 is stopped, the liquid refrigerant flowing out of the supercooling heat exchanger 6 passes through the check valve 8 and flows into the expansion valve 2.

The liquid refrigerant flowing into the expansion valve 2 is depressurized by the expansion valve 2 to become a low-temperature low-pressure gas-liquid two-phase refrigerant, and flows into the evaporator 3. The low-temperature low-pressure gas-liquid two-phase refrigerant that has flowed into the evaporator 3 exchanges heat with the indoor air to absorb and evaporate, and becomes a low-temperature low-pressure gas refrigerant that flows out of the evaporator 3. Then, the low-temperature low-pressure gas refrigerant flowing out of the evaporator 3 is sucked into the compressor 1.

(Flow of refrigerant during cooling operation by pump cycle)
The flow of the refrigerant during the cooling operation by the pump cycle will be described. The liquid refrigerant that has flowed into the refrigerant pump 5 is discharged from the refrigerant pump 5 and flows into the expansion valve 2. The liquid refrigerant that has flowed into the expansion valve 2 flows into the evaporator 3 without being depressurized by the expansion valve 2. The liquid refrigerant flowing into the evaporator 3 exchanges heat with the indoor air, absorbs heat and evaporates, becomes a gas refrigerant, and flows out from the evaporator 3.

Since the compressor 1 is stopped, the gas refrigerant flowing out of the evaporator 3 passes through the check valve 7 and flows into the condenser 10. The gas refrigerant flowing into the condenser 10 exchanges heat with the outdoor air and condenses while radiating heat, becomes a liquid refrigerant, and flows out from the condenser 10. The liquid refrigerant flowing out of the condenser 10 flows into the receiver 4, the amount of the refrigerant is adjusted, and the liquid refrigerant flows out from the receiver 4. The liquid refrigerant flowing out from the receiver 4 flows into the supercooling heat exchanger 6, and flows out from the supercooling heat exchanger 6 in a state where the degree of supercooling is increased by further cooling. Then, the liquid refrigerant flowing out of the supercooling heat exchanger 6 is sucked into the refrigerant pump 5.

In the pump cycle, the liquid refrigerant is depressurized due to the pressure loss of the piping from the refrigerant pump 5 to the refrigerant inflow side of the evaporator 3. On the other hand, when the evaporator 3 is arranged below the refrigerant pump 5, the liquid refrigerant may be boosted by the liquid head in the piping from the refrigerant pump 5 to the refrigerant inflow side of the evaporator 3. Therefore, in the pump cycle, it is necessary to consider both boosting and depressurizing by piping.

(Refrigerant circulation confirmation process)
The refrigerant circulation confirmation process by the air conditioner 100 according to the first embodiment will be described. If the refrigerant pump 5 is not driven in a state where the liquid refrigerant is sucked in, the refrigerant pump 5 may run idle and be damaged. Therefore, in the air conditioner 100, the refrigerant circulation confirmation process for determining whether or not the liquid refrigerant is sucked into the refrigerant pump 5 is performed while the refrigerant pump 5 is being driven.

Here, during the cooling operation by the pump cycle, the liquid refrigerant flows from the outlet of the refrigerant pump 5 to the inlet of the evaporator 3 as described above. Therefore, at the inlet of the evaporator 3, the refrigerant is a liquid refrigerant or a two-phase refrigerant having a degree of supercooling.

On the other hand, in the pump cycle, when the gas refrigerant is sucked into the refrigerant pump 5 and the refrigerant does not circulate, the liquid refrigerant is not supplied to the evaporator 3. Further, since the room temperature is higher than the evaporation temperature, the refrigerant in the evaporator 3 evaporates, and the refrigerant on the refrigerant inflow side of the evaporator 3 also changes to a gas refrigerant having a superheat degree.

From this, when the refrigerant flowing into the refrigerant inflow side of the evaporator 3 has a degree of superheat, the refrigerant does not circulate in the pump cycle, that is, the liquid refrigerant is not sucked into the refrigerant pump 5. It can be determined that it is in a state. Therefore, in the first embodiment, it is determined whether or not the liquid refrigerant is sucked into the refrigerant pump 5 based on the degree of superheat SH on the refrigerant inflow side of the evaporator 3 during the refrigerant circulation confirmation process. ..

FIG. 5 is a flowchart showing an example of the flow of the refrigerant circulation confirmation process by the air conditioner 100 according to the first embodiment. First, in step S1, the operation of the compressor 1 is stopped, the refrigerant pump 5 is driven, and the operation is performed by the pump cycle.

In step S2, the information acquisition unit 51 of the control device 50 acquires various sensor information from each of the pump suction pressure sensor 41, the pump suction temperature sensor 42, the evaporator inlet temperature sensor 43, and the evaporator outlet pressure sensor 44. In step S3, the supercooling degree calculation unit 52 supercooling degree SC based on the saturated liquid temperature obtained from the pump suction pressure acquired from the pump suction pressure sensor 41 and the pump suction temperature obtained from the pump suction temperature sensor 42. Is calculated.

In step S4, the comparison unit 54 compares the supercooling degree SC calculated in step S3 with the set supercooling degree SC _SET stored in the storage unit 56. As a result of the comparison, when the supercooling degree SC is equal to or higher than the set supercooling degree SC _SET (step S4: Yes), the process proceeds to step S5. On the other hand, when the supercooling degree SC is less than the set supercooling degree SC _SET (step S4: No), the comparison unit 54 determines that the refrigerant is not circulating. Then, the process proceeds to step S7.

In step S5, the superheat degree calculation unit 53 evaporates based on the saturated gas temperature obtained from the evaporator outlet pressure acquired from the evaporator outlet pressure sensor 44 and the evaporator inlet temperature acquired from the evaporator inlet temperature sensor 43. The degree of superheat SH on the refrigerant inflow side of the vessel 3 is calculated.

In step S6, the comparison unit 54 compares the superheat degree SH calculated in step S5 with the set superheat degree SH _SET stored in the storage unit 56. As a result of the comparison, when the superheat degree SH is equal to or higher than the set superheat degree SH _SET (step S6: Yes), the comparison unit 54 determines that the refrigerant is not circulating and the refrigerant is not discharged from the refrigerant pump 5. .. Then, the process proceeds to step S7.

On the other hand, when the superheat degree SH is less than the set superheat degree SH _SET (step S6: No), the comparison unit 54 determines that the refrigerant is circulating and the refrigerant is discharged from the refrigerant pump 5. Then, the process returns to step S2, and the operation by the pump cycle is continued.

In step S7, the equipment control unit 55 stops driving the refrigerant pump 5 and operates the compressor 1. As a result, the operation of the air conditioner 100 is switched from the operation by the pump cycle to the operation by the compression cycle.

As described above, in the air conditioner 100 according to the first embodiment, the supercooling degree SC obtained from the pump suction pressure and the pump suction temperature, and the superheat degree SH obtained from the evaporator outlet pressure and the evaporator inlet temperature. Based on the above, the presence or absence of refrigerant circulation can be determined. Therefore, even if a problem occurs in the sensor provided on the suction side of the refrigerant pump 5, it is possible to reliably determine the presence or absence of refrigerant circulation.

In the air conditioner 100 according to the first embodiment, when the supercooling degree SC is less than the set supercooling degree SC _SET , it is determined that the refrigerant is not circulating, and the supercooling degree SC is the set supercooling degree SC. When it is _SET or more, the superheat degree SH and the set superheat degree SH _SET are compared. Further, when the superheat degree SH is less than the set superheat degree SH _SET , it is determined that the refrigerant is circulating. As a result, even if at least one of the pump suction pressure sensor 41 and the pump suction temperature sensor 42 used for calculating the supercooling degree SC malfunctions and the supercooling degree SC cannot be obtained correctly, the refrigerant circulation The presence or absence can be reliably determined.

The air conditioner 100 according to the first embodiment is controlled so that the operation by the pump cycle is stopped when it is determined that the refrigerant is not circulated when the operation by the pump cycle is being performed. May be done. Further, when the operation by the pump cycle is performed and it is determined that the refrigerant is not circulated, the operation by the pump cycle may be switched to the operation by the compression cycle.

Embodiment 2.
Next, the second embodiment will be described. The second embodiment is different from the first embodiment in that the pump suction pressure sensor 41 and the pump suction temperature sensor 42 are excluded. In the second embodiment, the same reference numerals are given to the parts common to the first embodiment, and detailed description thereof will be omitted.

[Structure of air conditioner 200]
FIG. 6 is a refrigerant circuit diagram showing an example of the configuration of the air conditioner 200 according to the second embodiment. As shown in FIG. 6, the air conditioner 200 is formed with a refrigerant circulation circuit 101 in which a refrigerant circulates inside, as in the first embodiment. The refrigerant circulation circuit 101 includes a compressor 1, a condenser 10, an expansion valve 2, an evaporator 3, a receiver 4, a refrigerant pump 5, and a supercooling heat exchanger 6.

The air conditioner 200 according to the second embodiment includes an outdoor unit 210 and an indoor unit 120. The outdoor unit 210 includes a receiver 4, a refrigerant pump 5, a supercooling heat exchanger 6, a check valve 8, a first condenser 11, a second condenser 12, a bypass pipe 20, a first pipe 21, and a second pipe 22. , Bypass pipe 24, check valve 31, expansion valve 32 and expansion valve 33 are housed.

Further, the air conditioner 200 includes a control device 250. The control device 250 controls each part provided in the air conditioner 200. In particular, in the second embodiment, the control device 250 confirms the presence or absence of refrigerant circulation in the refrigerant circulation circuit 101 during the pump cycle based on the detection results of the evaporator inlet temperature sensor 43 and the evaporator outlet pressure sensor 44. Performs refrigerant circulation confirmation processing.

FIG. 7 is a functional block diagram showing an example of the configuration of the control device 250 of FIG. As shown in FIG. 7, the control device 250 includes an information acquisition unit 51, a superheat degree calculation unit 53, a comparison unit 54, an equipment control unit 55, and a storage unit 56. That is, the control device 250 according to the second embodiment has a configuration in which the supercooling degree calculation unit 52 is removed from the control device 50 according to the first embodiment.

In the second embodiment, the information acquisition unit 51 acquires the evaporator inlet temperature as sensor information from the evaporator inlet temperature sensor 43. Further, the information acquisition unit 51 acquires the evaporator outlet pressure as sensor information from the evaporator outlet pressure sensor 44. Then, the information acquisition unit 51 supplies the acquired evaporator inlet temperature and evaporator outlet pressure to the superheat degree calculation unit 53.

The control device 250 is configured with hardware such as a circuit device that realizes various functions by executing software on an arithmetic unit such as a microcomputer. The specific hardware configuration of the control device 250 is the same as that of FIGS. 3 and 4 described in the first embodiment.

[Operation of air conditioner 200]
Next, the operation of the air conditioner 200 will be described. The air conditioner 200 according to the second embodiment is a composite cycle type air conditioner capable of executing both a compression cycle and a pump cycle, similarly to the air conditioner 100 according to the first embodiment. Since the operation by the compression cycle and the operation by the pump cycle are the same as those in the first embodiment, the description thereof will be omitted here.

(Refrigerant circulation confirmation process)
The refrigerant circulation confirmation process by the air conditioner 200 according to the second embodiment will be described. In the second embodiment, a refrigerant circulation confirmation process for confirming the presence or absence of refrigerant circulation in the refrigerant circulation circuit 101 is performed based on the degree of superheat SH on the refrigerant inflow side of the evaporator 3.

FIG. 8 is a flowchart showing an example of the flow of the refrigerant circulation confirmation process by the air conditioner 200 according to the second embodiment. First, in step S11, the operation of the compressor 1 is stopped, the refrigerant pump 5 is driven, and the operation is performed by the pump cycle.

In step S12, the information acquisition unit 51 of the control device 50 acquires various sensor information from each of the evaporator inlet temperature sensor 43 and the evaporator outlet pressure sensor 44. In step S13, the superheat degree calculation unit 53 evaporates based on the saturated gas temperature obtained from the evaporator outlet pressure acquired from the evaporator outlet pressure sensor 44 and the evaporator inlet temperature acquired from the evaporator inlet temperature sensor 43. The degree of superheat SH on the refrigerant inflow side of the vessel 3 is calculated.

In step S14, the comparison unit 54 compares the superheat degree SH calculated in step S13 with the set superheat degree SH _SET stored in the storage unit 56. As a result of the comparison, when the superheat degree SH is equal to or higher than the set superheat degree SH _SET (step S14: Yes), the comparison unit 54 determines that the refrigerant is not circulating and the refrigerant is not discharged from the refrigerant pump 5. .. Then, the process proceeds to step S15.

On the other hand, when the superheat degree SH is less than the set superheat degree SH _SET (step S14: No), the comparison unit 54 determines that the refrigerant is circulating and the refrigerant is discharged from the refrigerant pump 5. Then, the process returns to step S12, and the operation by the pump cycle is continued.

In step S15, the equipment control unit 55 stops driving the refrigerant pump 5 and operates the compressor 1. As a result, the operation of the air conditioner 200 is switched from the operation by the pump cycle to the operation by the compression cycle.

As described above, in the air conditioner 200 according to the second embodiment, the degree of superheat SH on the refrigerant inflow side of the evaporator 3 obtained from the evaporator outlet pressure and the evaporator inlet temperature is calculated. Then, based on the calculated superheat degree SH, the presence or absence of refrigerant circulation is determined. Therefore, in the air conditioner 200 according to the second embodiment, the pump suction pressure sensor 41 and the pump suction temperature sensor 42 provided on the suction side of the refrigerant pump 5 become unnecessary, and the configuration can be simplified.

In the air conditioner 200 according to the second embodiment, when the superheat degree SH is less than the set superheat degree SH _SET , it is determined that the refrigerant is circulating. This makes it possible to determine the presence or absence of refrigerant circulation without using the pump suction pressure sensor 41 and the pump suction temperature sensor 42 provided on the suction side of the refrigerant pump 5.

Although embodiments 1 and 2 of the air conditioner have been described above, the air conditioner is not limited to the above-described embodiments 1 and 2, and various modifications and variations are made within a range that does not deviate from the gist. It can be applied. Although the air conditioner 100 or 200 has been described so that the operation by the compression cycle and the operation by the pump cycle can be switched and executed, this is not limited to this example. For example, the air conditioner 100 or 200 may only perform operation by pump cycle. In this case, if it is determined that the refrigerant is not circulating, the refrigerant pump 5 is stopped and the operation by the pump cycle is stopped.

1 Compressor, 2 Expansion valve, 3 Evaporator, 4 Receiver, 5 Refrigerator pump, 6 Overcooling heat exchanger, 7, 8 Check valve, 10 Condenser, 11 1st condenser, 12 2nd condenser, 20 , 23, 24 Bypass piping, 21 1st piping, 22 2nd piping, 31 Check valve, 32, 33 Expansion valve, 41 Pump suction pressure sensor, 42 Pump suction temperature sensor, 43 Evaporator inlet temperature sensor, 44 Evaporator Outlet pressure sensor, 50, 250 control device, 51 information acquisition unit, 52 overcooling degree calculation unit, 53 overheating degree calculation unit, 54 comparison unit, 55 equipment control unit, 56 storage unit, 61 processing circuit, 71 processor, 72 memory , 100, 200 air conditioner, 101 refrigerant circulation circuit, 110, 210 outdoor unit, 120 indoor unit.

Claims (6)

An air conditioner in which a refrigerant pump, an expansion valve, an evaporator, and a condenser are connected by piping to form a pump cycle in which the refrigerant circulates, and the operation is performed by the pump cycle.
An evaporator outlet pressure sensor that detects the evaporator outlet pressure of the refrigerant flowing out of the evaporator, and
An evaporator inlet temperature sensor that detects the evaporator inlet temperature of the refrigerant flowing into the evaporator, and
An air conditioner including a control device for determining the presence or absence of refrigerant circulation based on the degree of superheat on the refrigerant inflow side of the evaporator obtained from the evaporator outlet pressure and the evaporator inlet temperature. A pump suction pressure sensor that detects the pump suction pressure of the refrigerant sucked into the refrigerant pump, and
Further, a pump suction temperature sensor for detecting the pump suction temperature of the refrigerant sucked into the refrigerant pump is provided.
The control device is
The air conditioner according to claim 1, wherein the presence or absence of refrigerant circulation is determined based on the degree of supercooling on the suction side of the refrigerant pump obtained from the pump suction pressure and the pump suction temperature and the degree of superheat. The control device is
A superheat degree calculation unit that calculates the superheat degree on the refrigerant inflow side of the evaporator based on the evaporator outlet pressure and the evaporator inlet temperature.
A storage unit that stores the set superheat degree, which is a threshold value for the superheat degree, and
It has a comparison unit for comparing the superheat degree and the set superheat degree.
The air conditioner according to claim 1 or 2, wherein the comparison unit determines that the refrigerant is circulating when the degree of superheat is less than the set degree of superheat. The control device is
Further having a supercooling degree calculation unit for calculating the supercooling degree of the refrigerant flowing into the refrigerant pump based on the pump suction pressure and the pump suction temperature.
The storage unit is
Further memorize the set supercooling degree which is a threshold value for the supercooling degree,
The comparison unit
When the supercooling degree is equal to or higher than the set supercooling degree, the superheating degree is compared with the set superheating degree.
The air conditioner according to claim 3, which is subordinate to claim 2, wherein it is determined that the refrigerant is not circulating when the degree of supercooling is less than the set degree of supercooling. The control device is
The air conditioner according to any one of claims 1 to 4, wherein when the operation by the pump cycle is being performed and it is determined that the refrigerant is not circulating, the operation by the pump cycle is stopped. Further equipped with a compressor that compresses the refrigerant,
By connecting the compressor, the condenser, the expansion valve and the evaporator with pipes, a compression cycle in which the refrigerant circulates is formed.
The control device is
The invention according to any one of claims 1 to 4, wherein when the operation by the pump cycle is being performed and it is determined that the refrigerant is not circulating, the operation by the pump cycle is switched to the operation by the compression cycle. Air conditioner.

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